Solar Dynamics Observatory On-Orbit Jitter Testing, Analysis, and Mitigation Plans

NASA Technical Reports Server (NTRS)

Liu, Kuo-Chia (Alice); Blaurock, Carl A.; Bourkland, Kristin L.; Morgenstern, Wendy M.; Maghami, Peiman G.

2011-01-01

The Solar Dynamics Observatory (SDO) was designed to understand the Sun and the Sun s influence on Earth. SDO was launched on February 11, 2010 carrying three scientific instruments: the Atmospheric Imaging Assembly (AIA), the Helioseismic and Magnetic Imager (HMI), and the Extreme Ultraviolet Variability Experiment (EVE). Both AIA and HMI are sensitive to high frequency pointing perturbations and have sub-arcsecond level line-of-sight (LOS) jitter requirements. Extensive modeling and analysis efforts were directed in estimating the amount of jitter disturbing the science instruments. To verify the disturbance models and to validate the jitter performance prior to launch, many jitter-critical components and subassemblies were tested either by the mechanism vendors or at the NASA Goddard Space Flight Center (GSFC). Although detailed analysis and assembly level tests were performed to obtain good jitter predictions, there were still several sources of uncertainties in the system. The structural finite element model did not have all the modes correlated to test data at high frequencies (greater than 50 Hz). The performance of the instrument stabilization system was not known exactly but was expected to be close to the analytical model. A true disturbance-to-LOS observatory level test was not available due to the tight schedule of the flight spacecraft, the cost in time and manpower, difficulties in creating gravity negation systems, and risks of damaging flight hardware. To protect the observatory jitter performance against model uncertainties, the SDO jitter team devised several on-orbit jitter reduction plans in addition to reserve margins on analysis results. Since some of these plans severely restricted the capabilities of several spacecraft components (e.g. wheels and High Gain Antennas), the SDO team performed on-orbit jitter tests to determine which jitter reduction plans, if any, were necessary to satisfy science LOS jitter requirements. The SDO on

Solar Dynamics Observatory On-Orbit Jitter Testing, Analysis, and Mitigation Plans

NASA Technical Reports Server (NTRS)

Liu, Kuo-Chia; Blaurock, Carl A.; Bourkland, Kristin L.; Morgenstern, Wendy M.; Maghami, Peiman G.

2011-01-01

The recently launched Solar Dynamics Observatory (SDO) has two science instruments onboard that required sub-arcsecond pointing stability. Significant effort has been spent pre-launch to characterize the disturbances sources and validating jitter level at the component, sub-assembly, and spacecraft levels. However, an end-to-end jitter test emulating the flight condition was not performed on the ground due to cost and risk concerns. As a result, the true jitter level experienced on orbit remained uncertain prior to launch. Based on the pre-launch analysis, several operational constraints were placed on the observatory aimed to minimize the instrument jitter levels. If the actual jitter is below the analysis predictions, these operational constraints can be relaxed to reduce the burden of the flight operations team. The SDO team designed a three-day jitter test, utilizing the instrument sensors to measure pointing jitter up to 256 Hz. The test results were compared to pre-launch analysis predictions, used to determine which operational constraints can be relaxed, and analyzed for setting the jitter mitigation strategies for future SDO operations.

Non-Gaussian statistics of soliton timing jitter induced by amplifier noise.

PubMed

Ho, Keang-Po

2003-11-15

Based on first-order perturbation theory of the soliton, the Gordon-Haus timing jitter induced by amplifier noise is found to be non-Gaussian distributed. Both frequency and timing jitter have larger tail probabilities than Gaussian distribution given by the linearized perturbation theory. The timing jitter has a larger discrepancy from Gaussian distribution than does the frequency jitter.

Integrated Modeling Activities for the James Webb Space Telescope: Optical Jitter Analysis

NASA Technical Reports Server (NTRS)

Hyde, T. Tupper; Ha, Kong Q.; Johnston, John D.; Howard, Joseph M.; Mosier, Gary E.

2004-01-01

This is a continuation of a series of papers on the integrated modeling activities for the James Webb Space Telescope(JWST). Starting with the linear optical model discussed in part one, and using the optical sensitivities developed in part two, we now assess the optical image motion and wavefront errors from the structural dynamics. This is often referred to as "jitter: analysis. The optical model is combined with the structural model and the control models to create a linear structural/optical/control model. The largest jitter is due to spacecraft reaction wheel assembly disturbances which are harmonic in nature and will excite spacecraft and telescope structural. The structural/optic response causes image quality degradation due to image motion (centroid error) as well as dynamic wavefront error. Jitter analysis results are used to predict imaging performance, improve the structural design, and evaluate the operational impact of the disturbance sources.

Tape recorder effects on jitter and shimmer extraction.

PubMed

Doherty, E T; Shipp, T

1988-09-01

To test for possible contamination of acoustic analyses by record/reproduce systems, five sine waves of fixed frequency and amplitude were sampled directly by a computer and recorded simultaneously on four different tape formats (audio and FM reel-to-reel, audio cassette, and video cassette using pulse code modulation). Recordings were digitized on playback and with the direct samples analyzed for fundamental frequency, amplitude, jitter, and shimmer using a zero crossing interpolation scheme. Distortion introduced by any of the data acquisition systems is negligible when extracting average fundamental frequency or average amplitude. For jitter and shimmer estimation, direct sampling or the use of a video cassette recorder with pulse code modulation are clearly superior. FM recorders, although not quite as accurate, provide a satisfactory alternative to those methods. Audio reel-to-reel recordings are marginally adequate for jitter analysis whereas audio cassette recorders can introduce jitter and shimmer values that are greater than some reported values for normal talkers.

Goodbye Critter Jitters

ERIC Educational Resources Information Center

Eidietis, Laura; Gray, Stacey; Riggs, Leela; West, Bridgette; Coffman, Margaret

2007-01-01

What invertebrates make the best classroom pets? How should we care for each invertebrate? What type of inquiry activities could invertebrates support? How do elementary students respond to invertebrates? These were the questions investigated in The Critter Project, a three-week project that aimed to help students conquer their "critter jitters"…

Spark gap with low breakdown voltage jitter

DOEpatents

Rohwein, G.J.; Roose, L.D.

1996-04-23

Novel spark gap devices and electrodes are disclosed. The novel spark gap devices and electrodes are suitable for use in a variety of spark gap device applications. The shape of the electrodes gives rise to local field enhancements and reduces breakdown voltage jitter. Breakdown voltage jitter of approximately 5% has been measured in spark gaps according the invention. Novel electrode geometries and materials are disclosed. 13 figs.

An Adaptive Jitter Mechanism for Reactive Route Discovery in Sensor Networks

PubMed Central

Cordero, Juan Antonio; Yi, Jiazi; Clausen, Thomas

2014-01-01

This paper analyses the impact of jitter when applied to route discovery in reactive (on-demand) routing protocols. In multi-hop non-synchronized wireless networks, jitter—a small, random variation in the timing of message emission—is commonly employed, as a means to avoid collisions of simultaneous transmissions by adjacent routers over the same channel. In a reactive routing protocol for sensor and ad hoc networks, jitter is recommended during the route discovery process, specifically, during the network-wide flooding of route request messages, in order to avoid collisions. Commonly, a simple uniform jitter is recommended. Alas, this is not without drawbacks: when applying uniform jitter to the route discovery process, an effect called delay inversion is observed. This paper, first, studies and quantifies this delay inversion effect. Second, this paper proposes an adaptive jitter mechanism, designed to alleviate the delay inversion effect and thereby to reduce the route discovery overhead and (ultimately) allow the routing protocol to find more optimal paths, as compared to uniform jitter. This paper presents both analytical and simulation studies, showing that the proposed adaptive jitter can effectively decrease the cost of route discovery and increase the path quality. PMID:25111238

Influence of the platform jitter on intensity fluctuation for laser launch system

NASA Astrophysics Data System (ADS)

Zhang, Pengfei; Qiao, Chunhong; Huang, Tong; Zhang, Jinghui; Fan, Chengyu

2017-10-01

The jitter of the transmitting system can cause the light intensity fluctuation at the target position of the laser transmission, which affects the performance of the laser communication, imaging and the adaptive optical system. In this paper, the platform jitter is modeled by Gaussian random fluctuation phase and the analytic expression of the system jitter effect on the fluctuation of light intensity is obtained under the vacuum condition based on extended Huygens-Fresnel principle. The numerical simulation is compared with the theoretical expression and the consistency is obtained. At the same time, the influence of the jitter of the launch system on the intensity fluctuation of the target system under different turbulence conditions is analyzed by numerical simulation. The result show that normalized intensity fluctuation variance induced by platform jitter seems to be unrestricted. The jitter of the transmitting system has a more important influence on the fluctuation of the target position caused by the atmospheric turbulence, as the jitter increase. This result provides a reference for the application of the actual laser transmission system.

Image jitter enhances visual performance when spatial resolution is impaired.

PubMed

Watson, Lynne M; Strang, Niall C; Scobie, Fraser; Love, Gordon D; Seidel, Dirk; Manahilov, Velitchko

2012-09-06

Visibility of low-spatial frequency stimuli improves when their contrast is modulated at 5 to 10 Hz compared with stationary stimuli. Therefore, temporal modulations of visual objects could enhance the performance of low vision patients who primarily perceive images of low-spatial frequency content. We investigated the effect of retinal-image jitter on word recognition speed and facial emotion recognition in subjects with central visual impairment. Word recognition speed and accuracy of facial emotion discrimination were measured in volunteers with AMD under stationary and jittering conditions. Computer-driven and optoelectronic approaches were used to induce retinal-image jitter with duration of 100 or 166 ms and amplitude within the range of 0.5 to 2.6° visual angle. Word recognition speed was also measured for participants with simulated (Bangerter filters) visual impairment. Text jittering markedly enhanced word recognition speed for people with severe visual loss (101 ± 25%), while for those with moderate visual impairment, this effect was weaker (19 ± 9%). The ability of low vision patients to discriminate the facial emotions of jittering images improved by a factor of 2. A prototype of optoelectronic jitter goggles produced similar improvement in facial emotion discrimination. Word recognition speed in participants with simulated visual impairment was enhanced for interjitter intervals over 100 ms and reduced for shorter intervals. Results suggest that retinal-image jitter with optimal frequency and amplitude is an effective strategy for enhancing visual information processing in the absence of spatial detail. These findings will enable the development of novel tools to improve the quality of life of low vision patients.

Zero-crossing detector with sub-microsecond jitter and crosstalk

NASA Technical Reports Server (NTRS)

Dick, G. John; Kuhnle, Paul F.; Sydnor, Richard L.

1990-01-01

A zero-crossing detector (ZCD) was built and tested with a new circuit design which gives reduced time jitter compared to previous designs. With the new design, time jitter is reduced for the first time to a value which approaches that due to noise in the input amplifying stage. Additionally, with fiber-optic transmission of the output signal, crosstalk between units has been eliminated. The measured values are in good agreement with circuit noise calculations and approximately ten times lower than that for ZCD's presently installed in the JPL test facility. Crosstalk between adjacent units was reduced even more than the jitter.

Correcting spacecraft jitter in HiRISE images

USGS Publications Warehouse

Sutton, S. S.; Boyd, A.K.; Kirk, Randolph L.; Cook, Debbie; Backer, Jean; Fennema, A.; Heyd, R.; McEwen, A.S.; Mirchandani, S.D.; Wu, B.; Di, K.; Oberst, J.; Karachevtseva, I.

2017-01-01

Mechanical oscillations or vibrations on spacecraft, also called pointing jitter, cause geometric distortions and/or smear in high resolution digital images acquired from orbit. Geometric distortion is especially a problem with pushbroom type sensors, such as the High Resolution Imaging Science Experiment (HiRISE) instrument on board the Mars Reconnaissance Orbiter (MRO). Geometric distortions occur at a range of frequencies that may not be obvious in the image products, but can cause problems with stereo image correlation in the production of digital elevation models, and in measuring surface changes over time in orthorectified images. The HiRISE focal plane comprises a staggered array of fourteen charge-coupled devices (CCDs) with pixel IFOV of 1 microradian. The high spatial resolution of HiRISE makes it both sensitive to, and an excellent recorder of jitter. We present an algorithm using Fourier analysis to resolve the jitter function for a HiRISE image that is then used to update instrument pointing information to remove geometric distortions from the image. Implementation of the jitter analysis and image correction is performed on selected HiRISE images. Resulting corrected images and updated pointing information are made available to the public. Results show marked reduction of geometric distortions. This work has applications to similar cameras operating now, and to the design of future instruments (such as the Europa Imaging System).

Active suppression of acoustically induced jitter for the airborne laser

NASA Astrophysics Data System (ADS)

Glaese, Roger M.; Anderson, Eric H.; Janzen, Paul C.

2000-07-01

The Airborne Laser (ABL) system has extremely tight jitter requirements. Acoustic disturbances, such as those caused by the pressure recovery system of the high power laser, are a significant jitter source. Several technologies may be appropriate for reducing the acoustically induced jitter. The first choice for mitigation will be passive approaches, such as acoustic blankets. There is, however, some uncertainty whether these approaches will provide sufficient attenuation and there is concern about the weight of these approaches. A testbed that captured the fundamental physics of the ABL acoustically induced optical jitter problem was developed. This testbed consists of a flexure-mounted mirror exposed to an acoustic field that is generated outside a beam tube and then propagates within the tube. Both feedback and adaptive feedforward control topologies were implemented on the testbed using either of two actuators (a fast steering mirror and a secondary acoustic speaker located near the precision mirror), and a variety of sensors (microphones measuring the acoustic disturbance, accelerometers and microphones mounted on the precision optic, and an optical position sensing detector). This paper summarizes the results from these control topologies for reducing the acoustically induced jitter with some control topologies achieving in excess of 40 dB jitter reduction at a single frequency. This work was performed under an SBIR Phase I funded by the Air Force Research Laboratory Space Vehicles Directorate.

Adaptive Filter Techniques for Optical Beam Jitter Control and Target Tracking

DTIC Science & Technology

2008-12-01

OPTICAL BEAM JITTER CONTROL AND TARGET TRACKING Michael J. Beerer Civilian, United States Air Force B.S., University of California Irvine, 2006...TECHNIQUES FOR OPTICAL BEAM JITTER CONTROL AND TARGET TRACKING by Michael J. Beerer December 2008 Thesis Advisor: Brij N. Agrawal Co...DATE December 2008 3. REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE Adaptive Filter Techniques for Optical Beam Jitter

A pattern jitter free AFC scheme for mobile satellite systems

NASA Technical Reports Server (NTRS)

Yoshida, Shousei

1993-01-01

This paper describes a scheme for pattern jitter free automatic frequency control (AFC) with a wide frequency acquisition range. In this scheme, equalizing signals fed to the frequency discriminator allow pattern jitter free performance to be achieved for all roll-off factors. In order to define the acquisition range, frequency discrimination characateristics are analyzed on a newly derived frequency domain model. As a result, it is shown that a sufficiently wide acquisition range over a given system symbol rate can be achieved independent of symbol timing errors. Additionally, computer simulation demonstrates that frequency jitter performance improves in proportion to E(sub b)/N(sub 0) because pattern-dependent jitter is suppressed in the discriminator output. These results show significant promise for applciation to mobile satellite systems, which feature relatively low symbol rate transmission with an approximately 0.4-0.7 roll-off factor.

Voice Signals Produced With Jitter Through a Stochastic One-mass Mechanical Model.

PubMed

Cataldo, Edson; Soize, Christian

2017-01-01

The quasiperiodic oscillation of the vocal folds causes perturbations in the length of the glottal cycles, which are known as jitter. The observation of the glottal cycles variations suggests that jitter is a random phenomenon described by random deviations of the glottal cycle lengths in relation to a corresponding mean value and, in general, its values are expressed as a percentage of the duration of the glottal pulse. The objective of this paper is the construction of a stochastic model for jitter using a one-mass mechanical model of the vocal folds, which assumes complete right-left symmetry of the vocal folds, and which considers motions of the vocal folds only in the horizontal direction. The jitter has been the subject for researchers due to its important applications such as the identification of pathological voices (nodules in the vocal folds, paralysis of the vocal folds, or even, the vocal aging, among others). Large values for jitter variations can indicate a pathological characteristic of the voice. The corresponding stiffness of each vocal fold is considered as a stochastic process, and its modeling is proposed. The probability density function of the fundamental frequency related to the voice signals produced are constructed and compared for different levels of jitter. Some samples of synthesized voices in these cases are obtained. It is showed that jitter could be obtained using the model proposed. The Praat software was also used to verify the measures of jitter in the synthesized voice signals. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Low-Timing-Jitter Near-Infrared Single-Photon-Sensitive 16-Channel Intensified-Photodiode Detector

NASA Technical Reports Server (NTRS)

Krainak, Michael A.; Lu, Wei; Yang, Guangning; Sun, Xiaoli; Sykora, Derek; Jurkovic, Mike; Aebi, Verle; Costello, Ken; Burns, Richard

2011-01-01

We developed a 16-channel InGaAsP photocathode intensified-photodiode (IPD) detector with 78 ps (1-sigma) timing-jitter, less than 500 ps FWHM impulse response, greater than 15% quantum efficiency at 1064 nm wavelength with 131 kcps dark counts at 15 C.

Remote distribution of a mode-locked pulse train with sub 40-as jitter

NASA Astrophysics Data System (ADS)

Chen, Yi-Fei; Jiang, Jie; Jones, David J.

2006-12-01

Remote transfer of an ultralow-jitter microwave frequency reference signal is demonstrated using the pulse trains generated by a mode-locked fiber laser. The timing jitter in a ~ 30-m fiber link is reduced to 38 attoseconds (as) integrated over a bandwidth from 1 Hz to 10 MHz via active stabilization which represents a significant improvement over previously reported jitter performance. Our approach uses an all-optical generation of the synchronization error signal and an accompanying out-of-loop optical detection technique to verify the jitter performance.

Physical mechanisms of timing jitter in photon detection by current-carrying superconducting nanowires

NASA Astrophysics Data System (ADS)

Sidorova, Mariia; Semenov, Alexej; Hübers, Heinz-Wilhelm; Charaev, Ilya; Kuzmin, Artem; Doerner, Steffen; Siegel, Michael

2017-11-01

We studied timing jitter in the appearance of photon counts in meandering nanowires with different fractional amount of bends. Intrinsic timing jitter, which is the probability density function of the random time delay between photon absorption in current-carrying superconducting nanowire and appearance of the normal domain, reveals two different underlying physical mechanisms. In the deterministic regime, which is realized at large photon energies and large currents, jitter is controlled by position-dependent detection threshold in straight parts of meanders. It decreases with the increase in the current. At small photon energies, jitter increases and its current dependence disappears. In this probabilistic regime jitter is controlled by Poisson process in that magnetic vortices jump randomly across the wire in areas adjacent to the bends.

Jitter Test Program and On-Orbit Mitigation Strategies for Solar Dynamic Observatory

NASA Technical Reports Server (NTRS)

Liu, Kuo-Chia; Kenney, Thomas; Maghami, Peiman; Mule, Pete; Blaurock, Carl; Haile, William B.

2007-01-01

The Solar Dynamic Observatory (SDO) aims to study the Sun's influence on the Earth, the source, storage, and release of the solar energy, and the interior structure of the Sun. During science observations, the jitter stability at the instrument focal plane must be maintained to less than a fraction of an arcsecond for two of the SDO instruments. To meet these stringent requirements, a significant amount of analysis and test effort has been devoted to predicting the jitter induced from various disturbance sources. This paper presents an overview of the SDO jitter analysis approach and test effort performed to date. It emphasizes the disturbance modeling, verification, calibration, and validation of the high gain antenna stepping mechanism and the reaction wheels, which are the two largest jitter contributors. This paper also describes on-orbit mitigation strategies to protect the system from analysis model uncertainties. Lessons learned from the SDO jitter analyses and test programs are included in the paper to share the knowledge gained with the community.

Jitter model and signal processing techniques for pulse width modulation optical recording

NASA Technical Reports Server (NTRS)

Liu, Max M.-K.

1991-01-01

A jitter model and signal processing techniques are discussed for data recovery in Pulse Width Modulation (PWM) optical recording. In PWM, information is stored through modulating sizes of sequential marks alternating in magnetic polarization or in material structure. Jitter, defined as the deviation from the original mark size in the time domain, will result in error detection if it is excessively large. A new approach is taken in data recovery by first using a high speed counter clock to convert time marks to amplitude marks, and signal processing techniques are used to minimize jitter according to the jitter model. The signal processing techniques include motor speed and intersymbol interference equalization, differential and additive detection, and differential and additive modulation.

Fully-Coupled Dynamical Jitter Modeling of Momentum Exchange Devices

NASA Astrophysics Data System (ADS)

Alcorn, John

A primary source of spacecraft jitter is due to mass imbalances within momentum exchange devices (MEDs) used for fine pointing, such as reaction wheels (RWs) and variable-speed control moment gyroscopes (VSCMGs). Although these effects are often characterized through experimentation in order to validate pointing stability requirements, it is of interest to include jitter in a computer simulation of the spacecraft in the early stages of spacecraft development. An estimate of jitter amplitude may be found by modeling MED imbalance torques as external disturbance forces and torques on the spacecraft. In this case, MED mass imbalances are lumped into static and dynamic imbalance parameters, allowing jitter force and torque to be simply proportional to wheel speed squared. A physically realistic dynamic model may be obtained by defining mass imbalances in terms of a wheel center of mass location and inertia tensor. The fully-coupled dynamic model allows for momentum and energy validation of the system. This is often critical when modeling additional complex dynamical behavior such as flexible dynamics and fuel slosh. Furthermore, it is necessary to use the fully-coupled model in instances where the relative mass properties of the spacecraft with respect to the RWs cause the simplified jitter model to be inaccurate. This thesis presents a generalized approach to MED imbalance modeling of a rigid spacecraft hub with N RWs or VSCMGs. A discussion is included to convert from manufacturer specifications of RW imbalances to the parameters introduced within each model. Implementations of the fully-coupled RW and VSCMG models derived within this thesis are released open-source as part of the Basilisk astrodynamics software.

Study of Magnetic Damping Effect on Convection and Solidification Under G-Jitter Conditions

NASA Technical Reports Server (NTRS)

Li, Ben Q.; deGroh, H. C., III

1999-01-01

As shown by NASA resources dedicated to measuring residual gravity (SAMS and OARE systems), g-jitter is a critical issue affecting space experiments on solidification processing of materials. This study aims to provide, through extensive numerical simulations and ground based experiments, an assessment of the use of magnetic fields in combination with microgravity to reduce the g-jitter induced convective flows in space processing systems. We have so far completed asymptotic analyses based on the analytical solutions for g-jitter driven flow and magnetic field damping effects for a simple one-dimensional parallel plate configuration, and developed both 2-D and 3-D numerical models for g-jitter driven flows in simple solidification systems with and without presence of an applied magnetic field. Numerical models have been checked with the analytical solutions and have been applied to simulate the convective flows and mass transfer using both synthetic g-jitter functions and the g-jitter data taken from space flight. Some useful findings have been obtained from the analyses and the modeling results. Some key points may be summarized as follows: (1) the amplitude of the oscillating velocity decreases at a rate inversely proportional to the g-jitter frequency and with an increase in the applied magnetic field; (2) the induced flow approximately oscillates at the same frequency as the affecting g-jitter, but out of a phase angle; (3) the phase angle is a complicated function of geometry, applied magnetic field, temperature gradient and frequency; (4) g-jitter driven flows exhibit a complex fluid flow pattern evolving in time; (5) the damping effect is more effective for low frequency flows; and (6) the applied magnetic field helps to reduce the variation of solutal distribution along the solid-liquid interface. Work in progress includes numerical simulations and ground-based measurements. Both 2-D and 3-D numerical simulations are being continued to obtain further

Reaction Wheel Disturbance Modeling, Jitter Analysis, and Validation Tests for Solar Dynamics Observatory

NASA Technical Reports Server (NTRS)

Liu,Kuo-Chia; Maghami, Peiman; Blaurock, Carl

2008-01-01

The Solar Dynamics Observatory (SDO) aims to study the Sun's influence on the Earth by understanding the source, storage, and release of the solar energy, and the interior structure of the Sun. During science observations, the jitter stability at the instrument focal plane must be maintained to less than a fraction of an arcsecond for two of the SDO instruments. To meet these stringent requirements, a significant amount of analysis and test effort has been devoted to predicting the jitter induced from various disturbance sources. One of the largest disturbance sources onboard is the reaction wheel. This paper presents the SDO approach on reaction wheel disturbance modeling and jitter analysis. It describes the verification and calibration of the disturbance model, and ground tests performed for validating the reaction wheel jitter analysis. To mitigate the reaction wheel disturbance effects, the wheels will be limited to operate at low wheel speeds based on the current analysis. An on-orbit jitter test algorithm is also presented in the paper which will identify the true wheel speed limits in order to ensure that the wheel jitter requirements are met.

GABAergic excitation of spider mechanoreceptors increases information capacity by increasing entropy rather than decreasing jitter.

PubMed

Pfeiffer, Keram; French, Andrew S

2009-09-02

Neurotransmitter chemicals excite or inhibit a range of sensory afferents and sensory pathways. These changes in firing rate or static sensitivity can also be associated with changes in dynamic sensitivity or membrane noise and thus action potential timing. We measured action potential firing produced by random mechanical stimulation of spider mechanoreceptor neurons during long-duration excitation by the GABAA agonist muscimol. Information capacity was estimated from signal-to-noise ratio by averaging responses to repeated identical stimulation sequences. Information capacity was also estimated from the coherence function between input and output signals. Entropy rate was estimated by a data compression algorithm and maximum entropy rate from the firing rate. Action potential timing variability, or jitter, was measured as normalized interspike interval distance. Muscimol increased firing rate, information capacity, and entropy rate, but jitter was unchanged. We compared these data with the effects of increasing firing rate by current injection. Our results indicate that the major increase in information capacity by neurotransmitter action arose from the increased entropy rate produced by increased firing rate, not from reduction in membrane noise and action potential jitter.

A low timing jitter picosecond microchip laser pumped by pulsed LD

NASA Astrophysics Data System (ADS)

Wang, Sha; Wang, Yan-biao; Feng, Guoying; Zhou, Shou-huan

2016-07-01

SESAM passively Q-switched microchip laser is a very promising instrument to replace mode locked lasers to obtain picosecond pulses. The biggest drawback of a passively Q-switched microchip laser is its un-avoided large timing jitter, especially when the pump intensity is low, i.e. at low laser repetition rate range. In order to obtain a low timing jitter passively Q-switched picosecond microchip laser in the whole laser repetition rate range, a 1000 kHz pulsed narrow bandwidth Fiber Bragg Grating (FBG) stablized laser diode was used as the pump source. By tuning the pump intensity, we could control the output laser frequency. In this way, we achieved a very low timing jitter passively Q-switched picosecond laser at 2.13 mW, 111.1 kHz. The relative timing jitter was only 0.0315%, which was around 100 times smaller compared with a cw LD pumped microchip working at hundred kilohertz repetition rate frequency range.

Measuring the jitter of ring oscillators by means of information theory quantifiers

NASA Astrophysics Data System (ADS)

Antonelli, M.; De Micco, L.; Larrondo, H. A.

2017-02-01

Ring oscillators (RO's) are elementary blocks widely used in digital design. Jitter is unavoidable in RO's, its presence is an undesired behavior in many applications, as clock generators. On the contrary, jitter may be used as the noise source in RO-based true-random numbers generators (TRNG). Consequently, jitter measure is a relevant issue to characterize a RO, and it is the subject of this paper. The main contribution is the use of Information Theory Quantifiers (ITQ) as measures of RO's jitter. It is shown that among several ITQ evaluated, two of them emerge as good measures because they are independent of parameters used for their statistical determination. They turned out to be robust and may be implemented experimentally. We encountered that a dual entropy plane allows a visual comparison of results.

Reference-free, high-resolution measurement method of timing jitter spectra of optical frequency combs

PubMed Central

Kwon, Dohyeon; Jeon, Chan-Gi; Shin, Junho; Heo, Myoung-Sun; Park, Sang Eon; Song, Youjian; Kim, Jungwon

2017-01-01

Timing jitter is one of the most important properties of femtosecond mode-locked lasers and optical frequency combs. Accurate measurement of timing jitter power spectral density (PSD) is a critical prerequisite for optimizing overall noise performance and further advancing comb applications both in the time and frequency domains. Commonly used jitter measurement methods require a reference mode-locked laser with timing jitter similar to or lower than that of the laser-under-test, which is a demanding requirement for many laser laboratories, and/or have limited measurement resolution. Here we show a high-resolution and reference-source-free measurement method of timing jitter spectra of optical frequency combs using an optical fibre delay line and optical carrier interference. The demonstrated method works well for both mode-locked oscillators and supercontinua, with 2 × 10−9 fs2/Hz (equivalent to −174 dBc/Hz at 10-GHz carrier frequency) measurement noise floor. The demonstrated method can serve as a simple and powerful characterization tool for timing jitter PSDs of various comb sources including mode-locked oscillators, supercontinua and recently emerging Kerr-frequency combs; the jitter measurement results enabled by our method will provide new insights for understanding and optimizing timing noise in such comb sources. PMID:28102352

Finite Element Analysis of Magnetic Damping Effects on G-Jitter Induced Fluid Flow

NASA Technical Reports Server (NTRS)

Pan, Bo; Li, Ben Q.; deGroh, Henry C., III

1997-01-01

This paper reports some interim results on numerical modeling and analyses of magnetic damping of g-jitter driven fluid flow in microgravity. A finite element model is developed to represent the fluid flow, thermal and solute transport phenomena in a 2-D cavity under g-jitter conditions with and without an applied magnetic field. The numerical model is checked by comparing with analytical solutions obtained for a simple parallel plate channel flow driven by g-jitter in a transverse magnetic field. The model is then applied to study the effect of steady state g-jitter induced oscillation and on the solute redistribution in the liquid that bears direct relevance to the Bridgman-Stockbarger single crystal growth processes. A selection of computed results is presented and the results indicate that an applied magnetic field can effectively damp the velocity caused by g-jitter and help to reduce the time variation of solute redistribution.

Practical security analysis of continuous-variable quantum key distribution with jitter in clock synchronization

NASA Astrophysics Data System (ADS)

Xie, Cailang; Guo, Ying; Liao, Qin; Zhao, Wei; Huang, Duan; Zhang, Ling; Zeng, Guihua

2018-03-01

How to narrow the gap of security between theory and practice has been a notoriously urgent problem in quantum cryptography. Here, we analyze and provide experimental evidence of the clock jitter effect on the practical continuous-variable quantum key distribution (CV-QKD) system. The clock jitter is a random noise which exists permanently in the clock synchronization in the practical CV-QKD system, it may compromise the system security because of its impact on data sampling and parameters estimation. In particular, the practical security of CV-QKD with different clock jitter against collective attack is analyzed theoretically based on different repetition frequencies, the numerical simulations indicate that the clock jitter has more impact on a high-speed scenario. Furthermore, a simplified experiment is designed to investigate the influence of the clock jitter.

Coupled Optoelectronic Oscillators:. Application to Low-Jitter Pulse Generation

NASA Astrophysics Data System (ADS)

Yu, N.; Tu, M.; Maleki, L.

2002-04-01

Actively mode-locked Erbium-doped fiber lasers (EDFL) have been studied for generating stable ultra-fast pulses (< 2 ps) at high repetition rates (> 5 GHz) [1,2]. These devices can be compact and environmentally stable, quite suitable for fiber-based high-data-rate communications and optical ultra-fast analog-to-digital conversions (ADC) [3]. The pulse-to-pulse jitter of an EDFL-based pulse generator will be ultimately limited by the phase noise of the mode-locking microwave source (typically electronic frequency synthesizers). On the other hand, opto-electronic oscillators (OEO) using fibers have been demonstrated to generate ultra-low phase noise microwaves at 10 GHz and higher [4]. The overall phase noise of an OEO can be much lower than commercially available synthesizers at the offset-frequency range above 100 Hz. Clearly, ultra-low jitter pulses can be generated by taking advantage of the low phase noise of OEOs. In this paper, we report the progress in developing a new low-jitter pulse generator by combing the two technologies. In our approach, the optical oscillator (mode-locked EDFL) and the microwave oscillator (OEO) are coupled through a common Mach-Zehnder (MZ) modulator, thus named coupled opto-electronic oscillator (COEO) [5]. Based on the results of previous OEO study, we can expect a 10 GHz pulse train with jitters less than 10 fs.

Radial Velocities of Subgiant Stars and New Astrophysical Insights into RV Jitter

NASA Astrophysics Data System (ADS)

Luhn, Jacob; Bastien, Fabienne; Wright, Jason T.

2018-01-01

For nearly 20 years, the California Planet Search (CPS) has simultaneously monitored precise radial velocities and chromospheric activity levels of stars from Keck observatory to search for exoplanets. This sample provides a useful set of stars to better determine the dependence of RV jitter on flicker (which traces surface gravity) first shown in Bastien et al. (2014). We expand upon this initial work by examining a much larger sample of stars covering a much wider range of stellar parameters (effective temperature, surface gravity, and activity, among others). For more than 600 stars, there are enough RV measurements to distinguish this astrophysical jitter from accelerations due to orbital companions. To properly isolate RV jitter from these effects, we must first remove the RV signal due to these companions, including several previously unannounced giant planets around subgiant stars. We highlight some new results from our analysis of the CPS data. A more thorough understanding of the various sources of RV jitter and the underlying stellar phenomena that drive these intrinsic RV variations will enable more precise jitter estimates for RV follow-up targets such as those from K2 or the upcoming TESS mission.

Sub-femtosecond timing jitter, all-fiber, CNT-mode-locked Er-laser at telecom wavelength.

PubMed

Kim, Chur; Bae, Sangho; Kieu, Khanh; Kim, Jungwon

2013-11-04

We demonstrate a 490-attosecond timing jitter (integration bandwidth: 10 kHz - 39.4 MHz) optical pulse train from a 78.7-MHz repetition rate, all-fiber soliton Er laser mode-locked by a fiber tapered carbon nanotube saturable absorber (ft-CNT-SA). To achieve this jitter performance, we searched for a net cavity dispersion condition where the Gordon-Haus jitter is minimized while maintaining stable soliton mode-locking. Our result shows that optical pulse trains with well below a femtosecond timing jitter can be generated from a self-starting and robust all-fiber laser operating at telecom wavelength.

A low jitter PLL clock used for phase change memory

NASA Astrophysics Data System (ADS)

Xiao, Hong; Houpeng, Chen; Zhitang, Song; Daolin, Cai; Xi, Li

2013-02-01

A fully integrated low-jitter, precise frequency CMOS phase-locked loop (PLL) clock for the phase change memory (PCM) drive circuit is presented. The design consists of a dynamic dual-reset phase frequency detector (PFD) with high frequency acquisition, a novel low jitter charge pump, a CMOS ring oscillator based voltage-controlled oscillator (VCO), a 2nd order passive loop filter, and a digital frequency divider. The design is fabricated in 0.35 μm CMOS technology and consumes 20 mW from a supply voltage of 5 V. In terms of the PCM's program operation requirement, the output frequency range is from 1 to 140 MHz. For the 140 MHz output frequency, the circuit features a cycle-to-cycle jitter of 28 ps RMS and 250 ps peak-to-peak.

Study of Magnetic Damping Effect on Convection and Solidification Under G-Jitter Conditions

NASA Technical Reports Server (NTRS)

Li, Ben Q.; deGroh, H. C.

2001-01-01

As shown in space flight experiments, g-jitter is a critical issue affecting solidification processing of materials in microgravity. This study aims to provide, through extensive numerical simulations and ground based experiments, an assessment of the use of magnetic fields in combination with microgravity to reduce the g-jitter induced convective flows in space processing systems. Analytical solutions and 2-D and 3-D numerical models for g-jitter driven flows in simple solidification systems with and without the presence of an applied magnetic field have been developed and extensive analyses were carried out. A physical model was also constructed and PIV measurements compared reasonably well with predictions from numerical models. Some key points may be summarized as follows: (1) the amplitude of the oscillating velocity decreases at a rate inversely proportional to the g-jitter frequency and with an increase in the applied magnetic field; (2) the induced flow oscillates at approximately the same frequency as the affecting g-jitter, but out of a phase angle; (3) the phase angle is a complicated function of geometry, applied magnetic field, temperature gradient and frequency; (4) g-jitter driven flows exhibit a complex fluid flow pattern evolving in time; (5) the damping effect is more effective for low frequency flows; and (6) the applied magnetic field helps to reduce the variation of solutal distribution along the solid-liquid interface. Work in progress includes developing numerical models for solidification phenomena with the presence of both g-jitter and magnetic fields and developing a ground-based physical model to verify numerical predictions.

Quantitating Changes in Jitter and Spike Number Using Concentric Needle Electrodes in Amyotrophic Lateral Sclerosis Patients

PubMed Central

Liu, Ming-Sheng; Niu, Jing-Wen; Li, Yi; Guan, Yu-Zhou; Cui, Li-Ying

2016-01-01

Background: Single-fiber electromyography (SFEMG) has been suggested as a quantitative method for supporting chronic partial denervation in amyotrophic lateral sclerosis (ALS) by the revised EI Escorial criteria. Although concentric needle (CN) electrodes have been used to assess jitter in myasthenia gravis patients and healthy controls, there are few reports using CN electrodes to assess motor unit instability and denervation in neurogenic diseases. The aim of this study was to determine whether quantitative changes in jitter and spike number using CN electrodes could be used for ALS studies. Methods: Twenty-seven healthy controls and 23 ALS patients were studied using both CN and single-fiber needle (SFN) electrodes on the extensor digitorum communis muscle with an SFEMG program. The SFN-jitter and SFN-fiber density data were measured using SFN electrodes. The CN-jitter and spike number were measured using CN electrodes. Results: The mean CN-jitter was significantly increased in ALS patients (47.3 ± 17.0 μs) than in healthy controls (27.4 ± 3.3 μs) (P < 0.001). Besides, the mean spike number was significantly increased in ALS patients (2.5 ± 0.5) than in healthy controls (1.7 ± 0.3) (P < 0.001). The sensitivity and specificity in the diagnosis of ALS were 82.6% and 92.6% for CN-jitter (cut-off value: 32 μs), and 91.3% and 96.3% for the spike number (cut-off value: 2.0), respectively. There was no significant difference between the SFN-jitter and CN-jitter in ALS patients; meanwhile, there was no significant difference between the SFN-jitter and CN-jitter in healthy controls. Conclusion: CN-jitter and spike number could be used to quantitatively evaluate changes due to denervation-reinnervation in ALS. PMID:27098787

Least-squares deconvolution of evoked potentials and sequence optimization for multiple stimuli under low-jitter conditions.

PubMed

Bardy, Fabrice; Dillon, Harvey; Van Dun, Bram

2014-04-01

Rapid presentation of stimuli in an evoked response paradigm can lead to overlap of multiple responses and consequently difficulties interpreting waveform morphology. This paper presents a deconvolution method allowing overlapping multiple responses to be disentangled. The deconvolution technique uses a least-squared error approach. A methodology is proposed to optimize the stimulus sequence associated with the deconvolution technique under low-jitter conditions. It controls the condition number of the matrices involved in recovering the responses. Simulations were performed using the proposed deconvolution technique. Multiple overlapping responses can be recovered perfectly in noiseless conditions. In the presence of noise, the amount of error introduced by the technique can be controlled a priori by the condition number of the matrix associated with the used stimulus sequence. The simulation results indicate the need for a minimum amount of jitter, as well as a sufficient number of overlap combinations to obtain optimum results. An aperiodic model is recommended to improve reconstruction. We propose a deconvolution technique allowing multiple overlapping responses to be extracted and a method of choosing the stimulus sequence optimal for response recovery. This technique may allow audiologists, psychologists, and electrophysiologists to optimize their experimental designs involving rapidly presented stimuli, and to recover evoked overlapping responses. Copyright © 2013 International Federation of Clinical Neurophysiology. All rights reserved.

Jitter and phase noise of ADPLL due to PSN with deterministic frequency

NASA Astrophysics Data System (ADS)

Deng, Xiaoying; Yang, Jun; Wu, Jianhui

2011-09-01

In this article, jitter and phase noise of all-digital phase-locked loop due to power supply noise (PSN) with deterministic frequency are analysed. It leads to the conclusion that jitter and phase noise heavily depend on the noise frequency. Compared with jitter, phase noise is much less affected by the deterministic PSN. Our method is utilised to study a CMOS ADPLL designed and simulated in SMIC 0.13 µm standard CMOS process. A comparison between the results obtained by our method and those obtained by simulation and measurement proves the accuracy of the predicted model. When the digital controlled oscillator was corrupted by PSN with 100 mVpk-pk, the measured jitters were 33.9 ps at the rate of fG = 192 MHz and 148.5 ps at the rate of fG = 40 MHz. However, the measured phase noise was exactly the same except for two impulses appearing at 192 and 40 MHz, respectively.

Real-time operating system timing jitter and its impact on motor control

NASA Astrophysics Data System (ADS)

Proctor, Frederick M.; Shackleford, William P.

2001-12-01

General-purpose microprocessors are increasingly being used for control applications due to their widespread availability and software support for non-control functions like networking and operator interfaces. Two classes of real-time operating systems (RTOS) exist for these systems. The traditional RTOS serves as the sole operating system, and provides all OS services. Examples include ETS, LynxOS, QNX, Windows CE and VxWorks. RTOS extensions add real-time scheduling capabilities to non-real-time OSes, and provide minimal services needed for the time-critical portions of an application. Examples include RTAI and RTL for Linux, and HyperKernel, OnTime and RTX for Windows NT. Timing jitter is an issue in these systems, due to hardware effects such as bus locking, caches and pipelines, and software effects from mutual exclusion resource locks, non-preemtible critical sections, disabled interrupts, and multiple code paths in the scheduler. Jitter is typically on the order of a microsecond to a few tens of microseconds for hard real-time operating systems, and ranges from milliseconds to seconds in the worst case for soft real-time operating systems. The question of its significance on the performance of a controller arises. Naturally, the smaller the scheduling period required for a control task, the more significant is the impact of timing jitter. Aside from this intuitive relationship is the greater significance of timing on open-loop control, such as for stepper motors, than for closed-loop control, such as for servo motors. Techniques for measuring timing jitter are discussed, and comparisons between various platforms are presented. Techniques to reduce jitter or mitigate its effects are presented. The impact of jitter on stepper motor control is analyzed.

Measurement Techniques for Transmit Source Clock Jitter for Weak Serial RF Links

NASA Technical Reports Server (NTRS)

Lansdowne, Chatwin A.; Schlesinger, Adam M.

2010-01-01

Techniques for filtering clock jitter measurements are developed, in the context of controlling data modulation jitter on an RF carrier to accommodate low signal-to-noise ratio thresholds of high-performance error correction codes. Measurement artifacts from sampling are considered, and a tutorial on interpretation of direct readings is included.

G-Jitter Effects in Protein Crystal Growth - A Numerical Study

NASA Technical Reports Server (NTRS)

Ramachandran, N.; Baugher, C. R.

1995-01-01

The impact of spacecraft acceleration environment on Protein Crystal Growth (PCG) is studied. A brief overview of the Space Shuttle acceleration environment is provided followed by a simple scaling procedure used to obtain estimates of the flow and concentration field characteristics in PCG. A detailed two-dimensional numerical model is then used to simulate the PCG system response to different disturbance scenarios; viz. residual g effects, impulse type disturbances and oscillatory inputs. The results show that PCG is susceptible to g-jitter and is a good candidate for vibration isolation.

The Role of Perceived Speed in Vection: Does Perceived Speed Modulate the Jitter and Oscillation Advantages?

PubMed Central

Apthorp, Deborah; Palmisano, Stephen

2014-01-01

Illusory self-motion (‘vection’) in depth is strongly enhanced when horizontal/vertical simulated viewpoint oscillation is added to optic flow inducing displays; a similar effect is found for simulated viewpoint jitter. The underlying cause of these oscillation and jitter advantages for vection is still unknown. Here we investigate the possibility that perceived speed of motion in depth (MID) plays a role. First, in a 2AFC procedure, we obtained MID speed PSEs for briefly presented (vertically oscillating and smooth) radial flow displays. Then we examined the strength, duration and onset latency of vection induced by oscillating and smooth radial flow displays matched either for simulated or perceived MID speed. The oscillation advantage was eliminated when displays were matched for perceived MID speed. However, when we tested the jitter advantage in the same manner, jittering displays were found to produce greater vection in depth than speed-matched controls. In summary, jitter and oscillation advantages were the same across experiments, but slower MID speed was required to match jittering than oscillating stimuli. Thus, to the extent that vection is driven by perceived speed of MID, this effect is greater for oscillating than for jittering stimuli, which suggests that the two effects may arise from separate mechanisms. PMID:24651861

A novel fair active queue management algorithm based on traffic delay jitter

NASA Astrophysics Data System (ADS)

Wang, Xue-Shun; Yu, Shao-Hua; Dai, Jin-You; Luo, Ting

2009-11-01

In order to guarantee the quantity of data traffic delivered in the network, congestion control strategy is adopted. According to the study of many active queue management (AQM) algorithms, this paper proposes a novel active queue management algorithm named JFED. JFED can stabilize queue length at a desirable level by adjusting output traffic rate and adopting a reasonable calculation of packet drop probability based on buffer queue length and traffic jitter; and it support burst packet traffic through the packet delay jitter, so that it can traffic flow medium data. JFED impose effective punishment upon non-responsible flow with a full stateless method. To verify the performance of JFED, it is implemented in NS2 and is compared with RED and CHOKe with respect to different performance metrics. Simulation results show that the proposed JFED algorithm outperforms RED and CHOKe in stabilizing instantaneous queue length and in fairness. It is also shown that JFED enables the link capacity to be fully utilized by stabilizing the queue length at a desirable level, while not incurring excessive packet loss ratio.

An Experimental Study of a Low-Jitter Pulsed Electromagnetic Plasma Accelerator

NASA Technical Reports Server (NTRS)

Thio, Y. C. Francis; Lee, Michael; Eskridge, Richard; Smith, James; Martin, Adam; Rodgers, Stephen L. (Technical Monitor)

2001-01-01

An experimental plasma accelerator for a variety of applications under development at the NASA Marshall Space Flight Center is described. The accelerator is a pulsed plasma thruster and has been tested experimentally and plasma jet velocities of approximately 50 kilometers per second have been obtained. The plasma jet structure has been photographed with 10 ns exposure times to reveal a stable and repeatable plasma structure. Data for velocity profile information has been obtained using light pipes embedded in the gun walls to record the plasma transit at various barrel locations. Preliminary spatially resolved spectral data and magnetic field probe data are also presented. A high speed triggering system has been developed and tested as a means of reducing the gun "jitter". This jitter has been characterized and future work for second generation "ultra-low jitter" gun development is identified.

Photonic ADC: overcoming the bottleneck of electronic jitter.

PubMed

Khilo, Anatol; Spector, Steven J; Grein, Matthew E; Nejadmalayeri, Amir H; Holzwarth, Charles W; Sander, Michelle Y; Dahlem, Marcus S; Peng, Michael Y; Geis, Michael W; DiLello, Nicole A; Yoon, Jung U; Motamedi, Ali; Orcutt, Jason S; Wang, Jade P; Sorace-Agaskar, Cheryl M; Popović, Miloš A; Sun, Jie; Zhou, Gui-Rong; Byun, Hyunil; Chen, Jian; Hoyt, Judy L; Smith, Henry I; Ram, Rajeev J; Perrott, Michael; Lyszczarz, Theodore M; Ippen, Erich P; Kärtner, Franz X

2012-02-13

Accurate conversion of wideband multi-GHz analog signals into the digital domain has long been a target of analog-to-digital converter (ADC) developers, driven by applications in radar systems, software radio, medical imaging, and communication systems. Aperture jitter has been a major bottleneck on the way towards higher speeds and better accuracy. Photonic ADCs, which perform sampling using ultra-stable optical pulse trains generated by mode-locked lasers, have been investigated for many years as a promising approach to overcome the jitter problem and bring ADC performance to new levels. This work demonstrates that the photonic approach can deliver on its promise by digitizing a 41 GHz signal with 7.0 effective bits using a photonic ADC built from discrete components. This accuracy corresponds to a timing jitter of 15 fs - a 4-5 times improvement over the performance of the best electronic ADCs which exist today. On the way towards an integrated photonic ADC, a silicon photonic chip with core photonic components was fabricated and used to digitize a 10 GHz signal with 3.5 effective bits. In these experiments, two wavelength channels were implemented, providing the overall sampling rate of 2.1 GSa/s. To show that photonic ADCs with larger channel counts are possible, a dual 20-channel silicon filter bank has been demonstrated.

Analysis of Optimal Jitter Buffer Size for VoIP QoS under WiMAX Power-Saving Mode

NASA Astrophysics Data System (ADS)

Kim, Hyungsuk; Kim, Taehyoun

VoIP service is expected as one of the key applications of Mobile WiMAX, but the speech quality of VoIP service often suffers deterioration due to the fluctuating transmission delay called jitter. This is commonly ameliorated by a de-jitter buffer, and we aim to find the optimal size of de-jitter buffer to achieve speech quality comparable to PSTN. We developed a new model of the packet drops at the de-jitter buffer and the end-to-end packet delay which takes account of the additional delay introduced by the WiMAX power-saving mode. Using our model, we analyzed the optimal size of the de-jitter buffer for various network parameters, and showed that the results obtained by analysis accord with simulation results.

Light gas gun with reduced timing jitter

DOEpatents

Laabs, Gary W.; Funk, David J.; Asay, Blaine W.

1998-01-01

Gas gun with reduced timing jitter. A gas gun having a prepressurized projectile held in place with a glass rod in compression is described. The glass rod is destroyed with an explosive at a precise time which allows a restraining pin to be moved and free the projectile.

Broadly tunable, low timing jitter, high repetition rate optoelectronic comb generator

PubMed Central

Metcalf, A. J.; Quinlan, F.; Fortier, T. M.; Diddams, S. A.; Weiner, A. M.

2016-01-01

We investigate the low timing jitter properties of a tunable single-pass optoelectronic frequency comb generator. The scheme is flexible in that both the repetition rate and center frequency can be continuously tuned. When operated with 10 GHz comb spacing, the integrated residual pulse-to-pulse timing jitter is 11.35 fs (1 Hz to 10 MHz) with no feedback stabilization. The corresponding phase noise at 1 Hz offset from the photodetected 10 GHz carrier is −100 dBc/Hz. PMID:26865734

Effects of G-Jitter on Interfacial Dynamics of Two Miscible Liquids: Application of MIM

NASA Technical Reports Server (NTRS)

Duval, Walter M. B.; Tryggvason, Bjarni V.

2000-01-01

We designed an experiment to examine the effects of g-jitter on mixing of two miscible liquids using the Microgravity Vibration Isolation Mount (MIM). The global bifurcation of the interface was observed with the MIM operating alternatively to either transmit the g-jitter, isolate from the g-jitter or to provide controlled vibration levels with well defined amplitude and frequency content. With the MIM in isolation mode, the interface remains stationary indicating buoyancy induced convection is negligibly small such that mixing occurs via intrinsic mass diffusion without the masking effect of vibration driven convection. Analytical and computational results are in agreement with the experimental findings. Operation of the MIM in forced mode with conditions typical of g-jitter shows that vibration induced convective flows can excite instability mechanisms such as Kelvin-Helmholtz to generate large amplitude quasi-stationary waves oriented vertically for various cases with Stokes-Reynolds number in the range of 0.003 to 0.5. The two and four mode quasi-stationary waves are also predicted with a mathematical model. Though unplanned, the effect of a primary thruster filing was captured and shown to cause a catastrophic bifurcation, enhancing local mass transport. In light of the findings, experiments planned for the International Space Station should consider the potential effects of g-jitter.

Light gas gun with reduced timing jitter

DOEpatents

Laabs, G.W.; Funk, D.J.; Asay, B.W.

1998-06-09

Gas gun with reduced timing jitter is disclosed. A gas gun having a prepressurized projectile held in place with a glass rod in compression is described. The glass rod is destroyed with an explosive at a precise time which allows a restraining pin to be moved and free the projectile. 4 figs.

Influence of P300 latency jitter on event related potential-based brain-computer interface performance

NASA Astrophysics Data System (ADS)

Aricò, P.; Aloise, F.; Schettini, F.; Salinari, S.; Mattia, D.; Cincotti, F.

2014-06-01

Objective. Several ERP-based brain-computer interfaces (BCIs) that can be controlled even without eye movements (covert attention) have been recently proposed. However, when compared to similar systems based on overt attention, they displayed significantly lower accuracy. In the current interpretation, this is ascribed to the absence of the contribution of short-latency visual evoked potentials (VEPs) in the tasks performed in the covert attention modality. This study aims to investigate if this decrement (i) is fully explained by the lack of VEP contribution to the classification accuracy; (ii) correlates with lower temporal stability of the single-trial P300 potentials elicited in the covert attention modality. Approach. We evaluated the latency jitter of P300 evoked potentials in three BCI interfaces exploiting either overt or covert attention modalities in 20 healthy subjects. The effect of attention modality on the P300 jitter, and the relative contribution of VEPs and P300 jitter to the classification accuracy have been analyzed. Main results. The P300 jitter is higher when the BCI is controlled in covert attention. Classification accuracy negatively correlates with jitter. Even disregarding short-latency VEPs, overt-attention BCI yields better accuracy than covert. When the latency jitter is compensated offline, the difference between accuracies is not significant. Significance. The lower temporal stability of the P300 evoked potential generated during the tasks performed in covert attention modality should be regarded as the main contributing explanation of lower accuracy of covert-attention ERP-based BCIs.

An examination of anticipated g-jitter on Space Station and its effects on materials processes

NASA Technical Reports Server (NTRS)

Nelson, Emily

1992-01-01

Information on anticipated g-jitter on Space Station Freedom and the effect of the jitter on materials processes is given in viewgraph form. It was concluded that g-jitter will dominate the acceleration environment; that it is a 3D multifrequency phenomenon; and that it varies dramatically in orientation. Information is given on calculated or measured sources of residual acceleration, aerodynamic drag, Shuttle acceleration measurements, the Space Station environment, tolerable g-levels as a function of frequency, directional solidification, vapor crystal growth, protein crystal growth, float zones, and liquid bridges.

Sub-100 attosecond timing jitter from low-noise passively mode-locked solid-state laser at telecom wavelength.

PubMed

Portuondo-Campa, E; Paschotta, R; Lecomte, S

2013-08-01

We report on the ultralow timing jitter of the 100 MHz pulse trains generated by two identical passively mode-locked diode-pumped solid-state lasers (DPSSLs) emitting at 1556 nm. Ultralow timing jitter of 83 as (integrated from 10 kHz to 50 MHz) for one laser has been measured with a balanced optical cross-correlator as timing discriminator. Extremely low intensity noise has been measured as well. Several measurement techniques have been used and show similar jitter results. Different possible noise sources have been theoretically investigated and compared to the measured jitter power spectral density. It is found that although the measured integrated jitter is quite low, it is still significantly above the quantum limit in the considered frequency span. Therefore, there is a substantial potential for technical improvements that could make passively mode-locked DPSSL outperform fiber lasers as source of microwaves with low phase noise.

Micro-jitter attenuation of spaceborne cooler by using a blade-type hyperelastic shape memory alloy passive isolator

NASA Astrophysics Data System (ADS)

Kwon, Seong-Cheol; Jeon, Young-Hyeon; Oh, Hyun-Ung

2017-10-01

In this study, the primary design objective is to develop a passive isolator that can guarantee structural safety of the cooler assembly in a launch vibration environment without a launch locking mechanism, while effectively isolating the cooler-induced micro-jitter during the on-orbit operation of the cooler. To achieve the design objective, we focused on the utilization of characteristics of the hyperelastic shape memory effects. The major advantage of the isolator is that the micro-jitter isolation performance is much less sensitive to the aligned position of the isolator in comparison with the conventional isolator. Moreover, implementation of an additional 0g compensation device during a satellite level on-ground test, such as a jitter measurement test, is not required. In this study, the basic characteristics of the isolator were measured using the torque test and free vibration test. The micro-jitter attenuation capability and position sensitivity of the proposed isolator design were validated by the micro-jitter measurement test.

Short-period terrestrial planets and radial velocity stellar jitter.

NASA Astrophysics Data System (ADS)

Dumusque, Xavier

2015-01-01

Stellar jitter is the main limitation to ultra-precise radial velocity (RV) measurements. It currently precludes our ability to detect a planet like the Earth. Short-period terrestrial planets present first the advantage of inducing a stronger RV signal. In addition, the signal produced by these planets have a period completely different than stellar activity. This allows us, when the observational strategy is adequate, to decorrelate the planetary signal from the jitter induced by the star using filtering techniques. I will show the examples of Kepler-78b and Corot-7b, where the amplitude of the planetary signal can be detected, despite the stellar activity jitter that is 5 and 3 times larger, respectively. The cases of Alpha Cen Bb will also be reviewed, with a new reduction of the published data that increases the significance of the planetary signal.This project is funded by ETAEARTH, a transnational collaboration between European countries and the US (the Swiss Space Office, the Harvard Origin of Life Initiative, the Scottish Universities Physics Alliance, the University of Geneva, the Smithsonian Astrophysical Observatory, the Italian National Astrophysical Institute, the University of St. Andrews, Queens University Belfast, and the University of Edinburgh) setup to optimize the synergy between space-and ground-based data whose scientific potential for the characterization of extrasolar planets can only be fully exploited when analyzed together.

PLL jitter reduction by utilizing a ferroelectric capacitor as a VCO timing element.

PubMed

Pauls, Greg; Kalkur, Thottam S

2007-06-01

Ferroelectric capacitors have steadily been integrated into semiconductor processes due to their potential as storage elements within memory devices. Polarization reversal within ferroelectric capacitors creates a high nonlinear dielectric constant along with a hysteresis profile. Due to these attributes, a phase-locked loop (PLL), when based on a ferroelectric capacitor, has the advantage of reduced cycle-to-cycle jitter. PLLs based on ferroelectric capacitors represent a new research area for reduction of oscillator jitter.

Modelling the RV jitter of early-M dwarfs using tomographic imaging

NASA Astrophysics Data System (ADS)

Hébrard, É. M.; Donati, J.-F.; Delfosse, X.; Morin, J.; Moutou, C.; Boisse, I.

2016-09-01

In this paper, we show how tomographic imaging (Zeeman-Doppler imaging, ZDI) can be used to characterize stellar activity and magnetic field topologies, ultimately allowing us to filter out the radial velocity (RV) activity jitter of M dwarf moderate rotators. This work is based on spectropolarimetric observations of a sample of five weakly active early-M dwarfs (GJ 205, GJ 358, GJ 410, GJ 479, GJ 846) with HARPS-Pol and NARVAL. These stars have v sin I and RV jitters in the range 1-2 km s-1 and 2.7-10.0 m s-1 rms, respectively. Using a modified version of ZDI applied to sets of phase-resolved least-squares deconvolved profiles of unpolarized spectral lines, we are able to characterize the distribution of active regions at the stellar surfaces. We find that dark spots cover less than 2 per cent of the total surface of the stars of our sample. Our technique is efficient at modelling the rotationally modulated component of the activity jitter, and succeeds at decreasing the amplitude of this component by typical factors of 2-3 and up to 6 in optimal cases. From the rotationally modulated time series of circularly polarized spectra and with ZDI, we also reconstruct the large-scale magnetic field topology. These fields suggest that bistability of dynamo processes observed in active M dwarfs may also be at work for moderately active M dwarfs. Comparing spot distributions with field topologies suggest that dark spots causing activity jitter concentrate at the magnetic pole and/or equator, to be confirmed with future data on a larger sample.

A voltage-division-type low-jitter self-triggered repetition-rate switch.

PubMed

Su, Jian-Cang; Zeng, Bo; Gao, Peng-Cheng; Li, Rui; Wu, Xiao-Long; Zhao, Liang

2016-10-01

A voltage-division-type (V/N) low-jitter self-triggered multi-stage switch is put forward. It comprises of a triggered corona gap, several quasi-uniform-field gaps, and an inversion inductor. When the corona gap is in the stage of self-breakdown, the multi-stage gaps are triggered and the switch is closed via an over-voltage. This type of V/N switch has the advantage of compact structure since the auxiliary components like the gas-blowing system and the triggered system are eliminated from the whole system. It also has advantages such as low breakdown jitter and high energy efficiency. The dependence of the self-triggered voltage on the over-voltage factor and the switch operating voltage is deduced. A switch of this type is designed and fabricated and experiments to research its characteristics are conducted. The results show that this switch can operate on a voltage of 1 MV at 50 Hz and can generate 1000 successive pulses with a jitter as low as 3% and an energy efficiency as high as 90%. This V/N switch can work under a high repetition rate with a long lifetime.

Ultralow-jitter and -amplitude-noise semiconductor-based actively mode-locked laser.

PubMed

Quinlan, Franklyn; Gee, Sangyoun; Ozharar, Sarper; Delfyett, Peter J

2006-10-01

We report a semiconductor-based, low-noise, 10.24 GHz actively mode-locked laser with 4.65 fs of relative timing jitter and a 0.0365% amplitude fluctuation (1 Hz to 100 MHz) of the optical pulse train. The keys to obtaining this result were the laser's high optical power and the low phase noise of the rf source used to mode lock the laser. The low phase noise of the rf source not only improves the absolute and relative timing jitter of the laser, but also prevents coupling of the rf source phase noise to the pulse amplitude fluctuations by the mode-locked laser.

Influence of group-delay ripple on timing jitter induced by SPM and IXPM in systems with dispersion compensated by CFBG

NASA Astrophysics Data System (ADS)

Qin, Xi; Cao, Jihong; Chen, Yong; Zhang, Feng; Jian, Shuisheng

2007-08-01

An analytical expression was proposed to analyze the influence of group-delay ripple (GDR) on timing jitter induced by self-phase modulation (SPM) and intra-channel cross-phase modulation (IXPM) in pseudo-linear transmission systems when dispersion was compensated by chirped fiber Bragg grating (CFBG). Effects of ripple amplitude, period, and phase on timing jitter were discussed by theoretical and numerical analysis in detail. The results show that the influence of GDR on timing jitter changes linearly with the amplitude of GDR and whether it decreases or increases the timing jitter relies on the ripple period and ripple phase. Timing jitter induced by SPM and IXPM could be suppressed totally by adjusting the relative phase between the center frequency of the pulse and the ripples.

Somatosensory spatial attention modulates amplitudes, latencies, and latency jitter of laser-evoked brain potentials.

PubMed

Franz, Marcel; Nickel, Moritz M; Ritter, Alexander; Miltner, Wolfgang H R; Weiss, Thomas

2015-04-01

Several studies provided evidence that the amplitudes of laser-evoked potentials (LEPs) are modulated by attention. However, previous reports were based on across-trial averaging of LEP responses at the expense of losing information about intertrial variability related to attentional modulation. The aim of this study was to investigate the effects of somatosensory spatial attention on single-trial parameters (i.e., amplitudes, latencies, and latency jitter) of LEP components (N2 and P2). Twelve subjects participated in a sustained spatial attention paradigm while noxious laser stimuli (left hand) and noxious electrical stimuli (right hand) were sequentially delivered to the dorsum of the respective hand with nonnoxious air puffs randomly interspersed within the sequence of noxious stimuli. Participants were instructed to mentally count all stimuli (i.e., noxious and nonnoxious) applied to the attended location. Laser stimuli, presented to the attended hand (ALS), elicited larger single-trial amplitudes of the N2 component compared with unattended laser stimuli (ULS). In contrast, single-trial amplitudes of the P2 component were not significantly affected by spatial attention. Single-trial latencies of the N2 and P2 were significantly smaller for ALS vs. ULS. Additionally, the across-trial latency jitter of the N2 component was reduced for ALS. Conversely, the latency jitter of the P2 component was smaller for ULS compared with ALS. With the use of single-trial analysis, the study provided new insights into brain dynamics of LEPs related to spatial attention. Our results indicate that single-trial parameters of LEP components are differentially modulated by spatial attention. Copyright © 2015 the American Physiological Society.

A novel low-jitter plasma-jet triggered gas switch operated at a low working coefficient.

PubMed

Tie, Weihao; Liu, Shanhong; Liu, Xuandong; Zhang, Qiaogen; Pang, Lei; Liu, Longchen

2014-02-01

In this paper, we described the fabrication and testing of a novel plasma-jet triggered gas switch (PJTGS) operated at extremely low working coefficients with excellent triggered jitters. While the structure of the PJTGS is similar to that of a traditional three-electrode field-distortion gas switch, to improve its triggered performance we used a conical micro-plasma-gun with a needle-to-plate spark gap embedded in the trigger electrode. Applying a nanosecond pulse to the trigger electrode caused a spark discharge in the micro-plasma-gun. The electric field drove the discharge plasma to spray into the spark gap of the gas switch, causing fast breakdown. We tested the PJTGS with charging voltages of ±25 kV and a trigger voltage of +80 kV (5 ns rise time and 80 ns full width at half maximum) in two working modes. The PJTGS operated in Mode II had a lower triggered jitter and could be operated over a wider range of working coefficients than in Mode I under the same conditions. At working coefficients higher than 70%, we obtained sub-ns triggered jitters (<0.89 ns) from the PJTGS, at working coefficients lower than 50%, we obtained triggered jitters of 1.6-3.5 ns without no-fires or pre-fires. Even at a working coefficient of 27.4%, the PJTGS could still be triggered reliably with a delay time of 96.1 ns and a triggered jitter of 3.5 ns, respectively.

A novel trigger for pseudospark switch with high repetition rate, low jitter, and compact structure

NASA Astrophysics Data System (ADS)

Yan, Jiaqi; Shen, Saikang; Wang, Yanan; Zhang, Siyu; Cheng, Le; Ding, Weidong

2018-06-01

This paper presents the design and development of a trigger with a high repetition rate, low jitter, and compact structure for the pseudospark switch (PSS), which includes an improved Marx generator based on avalanche transistors and a corona-plasma trigger unit. The generator adopted a novel 3 × 12-stage Marx circuit based on avalanche transistors in which the failure rate of transistors in the first and second stages was significantly reduced by connecting the parallel capacitors compared to the previous similar generator. The reason for the improved performance was also discussed. The main parameters of output pulses were an amplitude of -7 kV, rise time of 6 ns, jitter of 0.2 ns, and repetition rate of 2 kHz. The corona-plasma trigger unit adopted BaTiO3 ceramics with high ɛr as the dielectric and was arranged in the hollow cathode of the PSS. The experiments of triggering a PSS prototype were conducted. The influence of anode voltage and pressure on the trigger delay and jitter was studied, and the minimum trigger jitter achieved <1 ns. This trigger worked for 107 shots at the repetition rate of 2 kHz continuously without obvious performance degradation and any failure of the generator. The main advantage of this trigger is the simultaneous combination of the high repetition rate, low jitter, long lifetime, and great simplicity in a compact structure.

The development of high-voltage repetitive low-jitter corona stabilized triggered switch

NASA Astrophysics Data System (ADS)

Geng, Jiuyuan; Yang, Jianhua; Cheng, Xinbing; Yang, Xiao; Chen, Rong

2018-04-01

The high-power switch plays an important part in a pulse power system. With the trend of pulse power technology toward modularization, miniaturization, and accuracy control, higher requirements on electrical trigger and jitter of the switch have been put forward. A high-power low-jitter corona-stabilized triggered switch (CSTS) is designed in this paper. This kind of CSTS is based on corona stabilized mechanism, and it can be used as a main switch of an intense electron-beam accelerator (IEBA). Its main feature was the use of an annular trigger electrode instead of a traditional needle-like trigger electrode, taking main and side trigger rings to fix the discharging channels and using SF6/N2 gas mixture as its operation gas. In this paper, the strength of the local field enhancement was changed by a trigger electrode protrusion length Dp. The differences of self-breakdown voltage and its stability, delay time jitter, trigger requirements, and operation range of the switch were compared. Then the effect of different SF6/N2 mixture ratio on switch performance was explored. The experimental results show that when the SF6 is 15% with the pressure of 0.2 MPa, the hold-off voltage of the switch is 551 kV, the operating range is 46.4%-93.5% of the self-breakdown voltage, the jitter is 0.57 ns, and the minimum trigger voltage requirement is 55.8% of the peak. At present, the CSTS has been successfully applied to an IEBA for long time operation.

The development of high-voltage repetitive low-jitter corona stabilized triggered switch.

PubMed

Geng, Jiuyuan; Yang, Jianhua; Cheng, Xinbing; Yang, Xiao; Chen, Rong

2018-04-01

The high-power switch plays an important part in a pulse power system. With the trend of pulse power technology toward modularization, miniaturization, and accuracy control, higher requirements on electrical trigger and jitter of the switch have been put forward. A high-power low-jitter corona-stabilized triggered switch (CSTS) is designed in this paper. This kind of CSTS is based on corona stabilized mechanism, and it can be used as a main switch of an intense electron-beam accelerator (IEBA). Its main feature was the use of an annular trigger electrode instead of a traditional needle-like trigger electrode, taking main and side trigger rings to fix the discharging channels and using SF 6 /N 2 gas mixture as its operation gas. In this paper, the strength of the local field enhancement was changed by a trigger electrode protrusion length Dp. The differences of self-breakdown voltage and its stability, delay time jitter, trigger requirements, and operation range of the switch were compared. Then the effect of different SF 6 /N 2 mixture ratio on switch performance was explored. The experimental results show that when the SF 6 is 15% with the pressure of 0.2 MPa, the hold-off voltage of the switch is 551 kV, the operating range is 46.4%-93.5% of the self-breakdown voltage, the jitter is 0.57 ns, and the minimum trigger voltage requirement is 55.8% of the peak. At present, the CSTS has been successfully applied to an IEBA for long time operation.

Multi-megavolt low jitter multistage switch

DOEpatents

Humphreys, D.R.; Penn, K.J. Jr.

1985-06-19

It is one object of the present invention to provide a multistage switch capable of holding off numerous megavolts, until triggered, from a particle beam accelerator of the type used for inertial confinement fusion. The invention provides a multistage switch having low timing jitter and capable of producing multiple spark channels for spreading current over a wider area to reduce electrode damage and increase switch lifetime. The switch has fairly uniform electric fields and a short spark gap for laser triggering and is engineered to prevent insulator breakdowns.

Time-jittered marine seismic data acquisition via compressed sensing and sparsity-promoting wavefield reconstruction

NASA Astrophysics Data System (ADS)

Wason, H.; Herrmann, F. J.; Kumar, R.

2016-12-01

Current efforts towards dense shot (or receiver) sampling and full azimuthal coverage to produce high resolution images have led to the deployment of multiple source vessels (or streamers) across marine survey areas. Densely sampled marine seismic data acquisition, however, is expensive, and hence necessitates the adoption of sampling schemes that save acquisition costs and time. Compressed sensing is a sampling paradigm that aims to reconstruct a signal--that is sparse or compressible in some transform domain--from relatively fewer measurements than required by the Nyquist sampling criteria. Leveraging ideas from the field of compressed sensing, we show how marine seismic acquisition can be setup as a compressed sensing problem. A step ahead from multi-source seismic acquisition is simultaneous source acquisition--an emerging technology that is stimulating both geophysical research and commercial efforts--where multiple source arrays/vessels fire shots simultaneously resulting in better coverage in marine surveys. Following the design principles of compressed sensing, we propose a pragmatic simultaneous time-jittered time-compressed marine acquisition scheme where single or multiple source vessels sail across an ocean-bottom array firing airguns at jittered times and source locations, resulting in better spatial sampling and speedup acquisition. Our acquisition is low cost since our measurements are subsampled. Simultaneous source acquisition generates data with overlapping shot records, which need to be separated for further processing. We can significantly impact the reconstruction quality of conventional seismic data from jittered data and demonstrate successful recovery by sparsity promotion. In contrast to random (sub)sampling, acquisition via jittered (sub)sampling helps in controlling the maximum gap size, which is a practical requirement of wavefield reconstruction with localized sparsifying transforms. We illustrate our results with simulations of

Efficient modeling of phase jitter in dispersion-managed soliton systems.

PubMed

McKinstrie, C J; Xie, C; Lakoba, T I

2002-11-01

The variational method is used to derive correlation equations that model phase jitter in dispersion-managed soliton systems. The predictions of these correlation equations are consistent with numerical solutions of the nonlinear Schrödinger equation on which they are based.

Low jitter, low inductance solid dielectric switches.

PubMed

Guenther, A H; Strickland, D M; Bettis, J R

1979-11-01

It has been shown that the use of graded solid dielectric sandwiches in laser-triggered spark gaps (LTS) can lead to highly desirable multichannel operations while maintaining the low delay and jitter performance characteristics of LTS. As many as ten separate breakdown channels were observed when small circular or hexagonal aluminum inserts were inserted between two Mylar dielectric sheets stressed at 4.1 kV/mil. A reduction in rise time was noted for these multichannel switching events.

Avalanche buildup and propagation effects on photon-timing jitter in Si-SPAD with non-uniform electric field

NASA Astrophysics Data System (ADS)

Ingargiola, Antonino; Assanelli, Mattia; Gallivanoni, Andrea; Rech, Ivan; Ghioni, Massimo; Cova, Sergio

2009-05-01

Improving SPAD performances, such as dark count rate and quantum efficiency, without degrading the photontiming jitter is a challenging task that requires a clear understanding of the physical mechanisms involved. In this paper we investigate the contribution of the avalanche buildup statistics and the lateral avalanche propagation to the photon-timing jitter in silicon SPAD devices. Recent works on the buildup statistics focused on the uniform electric field case, however these results can not be applied to Si SPAD devices in which field profile is far from constant. We developed a 1-D Monte Carlo (MC) simulator using the real non-uniform field profiles derived from Secondary Ion Mass Spectroscopy (SIMS) measurements. Local and non-local models for impact ionization phenomena were considered. The obtained results, in particular the mean multiplication rate and jitter of the buildup filament, allowed us to simulate the statistical spread of the avalanche current on the device active area. We included space charge effects and a detailed lumped model for the external electronics and parasitics. We found that, in agreement with some experimental evidences, the avalanche buildup contribution to the total timing jitter is non-negligible in our devices. Moreover the lateral propagation gives an additional contribution that can explain the increasing trend of the photon-timing jitter with the comparator threshold.

Requirements Formulation and Dynamic Jitter Analysis for Fourier-Kelvin Stellar Interferometer

NASA Technical Reports Server (NTRS)

Liu, Kuo-Chia; Hyde, Tristram; Blaurock, Carl; Bolognese, Jeff; Howard, Joseph; Danchi, William

2004-01-01

The Fourier-Kelvin Stellar Interferometer (FKSI) has been proposed to detect and characterize extra solar giant planets. The baseline configuration for FKSI is a two- aperture, structurally connected nulling interferometer, capable of providing null depth less than lo4 in the infrared. The objective of this paper is to summarize the process for setting the top level requirements and the jitter analysis performed on FKSI to date. The first part of the paper discusses the derivation of dynamic stability requirements, necessary for meeting the FKSI nulling demands. An integrated model including structures, optics, and control systems has been developed to support dynamic jitter analysis and requirements verification. The second part of the paper describes how the integrated model is used to investigate the effects of reaction wheel disturbances on pointing and optical path difference stabilities.

Phase jitter in a differential phase experiment.

NASA Technical Reports Server (NTRS)

Tanenbaum, B. S.; Connolly, D. J.; Austin, G. L.

1973-01-01

Austin (1971) had concluded that, because of the 'phase jitter,' the differential phase experiment is useful over a more limited height range than the differential absorption experiment. Several observations are presented to show that this conclusion is premature. It is pointed out that the logical basis of the differential absorption experiment also requires that the O- and X-mode echoes, at a given time, come from the same irregularities. Austin's calculations are believed to contain a systematic error above 80 km.

Sloshing dynamics modulated fluid angular momentum and moment fluctuations driven by orbital gravity gradient and jitter accelerations in microgravity

NASA Technical Reports Server (NTRS)

Hung, R. J.; Pan, H. L.

1995-01-01

The dynamical behavior of spacecraft propellant affected by the asymmetric combined gravity gradient and jitter accelerations, in particular the effect of surface tension on partially-filled rotating fluids applicable to a full-scale Gravity Probe-B Spacecraft dewar tank has been investigated. Three different cases of orbital accelerations: (1) gravity gradient-dominated, (2) equally weighted between gravity gradient and jitter, and (3) gravity jitter-dominated accelerations are studied. The results of slosh wave excitation along the liquid-vapor interface induced by gravity gradient-dominated accelerations provide a torsional moment with tidal motion of bubble oscillations in the rotating dewar. The results are clearly seen from the twisting shape of the bubble oscillations driven by gravity gradient-dominated acceleration. The results of slosh wave excitation along the liquid-vapor interface induced by gravity jitter-dominated acceleration indicate the results of bubble motion in a manner of down-and-up and leftward-and-rightward movement of oscillation when the bubble is rotating with respect to rotating dewar axis. Fluctuations of angular momentum, fluid moment and bubble mass center caused by slosh wave excitations driven by gravity gradient acceleration or gravity jitter acceleration are also investigated.

Reduction of timing jitter in passively Q-switched microchip lasers using self-injection seeding.

PubMed

Steinmetz, Alexander; Nodop, Dirk; Martin, Andreas; Limpert, Jens; Tünnermann, Andreas

2010-09-01

We present an efficient, simple, and passive technique for the reduction of timing jitter in passively Q-switched microchip lasers via self-injection seeding using a fiber delay line. The presented approach mitigates one inherent issue of passively Q-switched lasers without the need for active stabilization. At a repetition rate of a few hundred kilohertz and pulse duration of approximately 200 ps delivered by a microchip laser, the rms jitter is reduced from several nanoseconds down to 20 ps, hence, significantly below the pulse duration of the laser source.

RF Jitter Modulation Alignment Sensing

NASA Astrophysics Data System (ADS)

Ortega, L. F.; Fulda, P.; Diaz-Ortiz, M.; Perez Sanchez, G.; Ciani, G.; Voss, D.; Mueller, G.; Tanner, D. B.

2017-01-01

We will present the numerical and experimental results of a new alignment sensing scheme which can reduce the complexity of alignment sensing systems currently used, while maintaining the same shot noise limited sensitivity. This scheme relies on the ability of electro-optic beam deflectors to create angular modulation sidebands in radio frequency, and needs only a single-element photodiode and IQ demodulation to generate error signals for tilt and translation degrees of freedom in one dimension. It distances itself from current techniques by eliminating the need for beam centering servo systems, quadrant photodetectors and Gouy phase telescopes. RF Jitter alignment sensing can be used to reduce the complexity in the alignment systems of many laser optical experiments, including LIGO and the ALPS experiment.

Reduction of timing jitter and intensity noise in normal-dispersion passively mode-locked fiber lasers by narrow band-pass filtering.

PubMed

Qin, Peng; Song, Youjian; Kim, Hyoji; Shin, Junho; Kwon, Dohyeon; Hu, Minglie; Wang, Chingyue; Kim, Jungwon

2014-11-17

Fiber lasers mode-locked with normal cavity dispersion have recently attracted great attention due to large output pulse energy and femtosecond pulse duration. Here we accurately characterized the timing jitter of normal-dispersion fiber lasers using a balanced cross-correlation method. The timing jitter characterization experiments show that the timing jitter of normal-dispersion mode-locked fiber lasers can be significantly reduced by using narrow band-pass filtering (e.g., 7-nm bandwidth filtering in this work). We further identify that the timing jitter of the fiber laser is confined in a limited range, which is almost independent of cavity dispersion map due to the amplifier-similariton formation by insertion of the narrow bandpass filter. The lowest observed timing jitter reaches 0.57 fs (rms) integrated from 10 kHz to 10 MHz Fourier frequency. The rms relative intensity noise (RIN) is also reduced from 0.37% to 0.02% (integrated from 1 kHz to 5 MHz Fourier frequency) by the insertion of narrow band-pass filter.

Broadband noise limit in the photodetection of ultralow jitter optical pulses.

PubMed

Sun, Wenlu; Quinlan, Franklyn; Fortier, Tara M; Deschenes, Jean-Daniel; Fu, Yang; Diddams, Scott A; Campbell, Joe C

2014-11-14

Applications with optical atomic clocks and precision timing often require the transfer of optical frequency references to the electrical domain with extremely high fidelity. Here we examine the impact of photocarrier scattering and distributed absorption on the photocurrent noise of high-speed photodiodes when detecting ultralow jitter optical pulses. Despite its small contribution to the total photocurrent, this excess noise can determine the phase noise and timing jitter of microwave signals generated by detecting ultrashort optical pulses. A Monte Carlo simulation of the photodetection process is used to quantitatively estimate the excess noise. Simulated phase noise on the 10 GHz harmonic of a photodetected pulse train shows good agreement with previous experimental data, leading to the conclusion that the lowest phase noise photonically generated microwave signals are limited by photocarrier scattering well above the quantum limit of the optical pulse train.

Variable Delay Element For Jitter Control In High Speed Data Links

DOEpatents

Livolsi, Robert R.

2002-06-11

A circuit and method for decreasing the amount of jitter present at the receiver input of high speed data links which uses a driver circuit for input from a high speed data link which comprises a logic circuit having a first section (1) which provides data latches, a second section (2) which provides a circuit generates a pre-destorted output and for compensating for level dependent jitter having an OR function element and a NOR function element each of which is coupled to two inputs and to a variable delay element as an input which provides a bi-modal delay for pulse width pre-distortion, a third section (3) which provides a muxing circuit, and a forth section (4) for clock distribution in the driver circuit. A fifth section is used for logic testing the driver circuit.

Astrometric Jitter of the Sun as a Star

DTIC Science & Technology

2010-05-01

active, fast-rotating stars. The research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology...as the Sun is not affected by star spot noise, but the prospects for more active stars may be limited to giant planets. Subject headings: open clusters ...nearby dwarfs should be as amenable to exoplanet detection as the Sun. The aim of this paper is to determine the solar astrometric jitter directly

Multifrequency zero-jitter delay-locked loop

NASA Astrophysics Data System (ADS)

Efendovich, Avner; Afek, Yachin; Sella, Coby; Bikowsky, Zeev

1994-01-01

The approach of an all-digital phase locked loop is used in this delay-locked loop circuit. This design is designated to a system with two processing units, a master CPU and a slave system chip, that share the same bus. It allows maximum utilization of the bus, as the minimal skew between the clocks of the two components significantly reduces idle periods, and also set-up and hold times. Changes in the operating frequency are possible, without falling out of synchronization. Due to the special lead-lag phase detector, the jitter of the clock is zero, when the loop is locked, under any working conditions.

Intracavity dispersion effect on timing jitter of ultralow noise mode-locked semiconductor based external-cavity laser.

PubMed

Gee, S; Ozharar, S; Plant, J J; Juodawlkis, P W; Delfyett, P J

2009-02-01

We report the generation of optical pulse trains with 380 as of residual timing jitter (1 Hz-1 MHz) from a mode-locked external-cavity semiconductor laser, through a combination of optimizing the intracavity dispersion and utilizing a high-power, low-noise InGaAsP quantum-well slab-coupled optical waveguide amplifier gain medium. This is, to our knowledge, the lowest residual timing jitter reported to date from an actively mode-locked laser.

Effect of Magnetic Fields on g-jitter Induced Convection and Solute Striation During Space Processing of Single Crystals

NASA Technical Reports Server (NTRS)

deGroh, H. C.; Li, K.; Li, B. Q.

2002-01-01

A 2-D finite element model is presented for the melt growth of single crystals in a microgravity environment with a superimposed DC magnetic field. The model is developed based on the deforming finite element methodology and is capable of predicting the phenomena of the steady and transient convective flows, heat transfer, solute distribution, and solid-liquid interface morphology associated with the melt growth of single crystals in microgravity with and without an applied magnetic field. Numerical simulations were carried out for a wide range of parameters including idealized microgravity conditions, the synthesized g-jitter and the real g-jitter data taken by on-board accelerometers during space flights. The results reveal that the time varying g-jitter disturbances, although small in magnitude, cause an appreciable convective flow in the liquid pool, which in turn produces detrimental effects during the space processing of single crystal growth. An applied magnetic field of appropriate strength, superimposed on microgravity, can be very effective in suppressing the deleterious effects resulting from the g-jitter disturbances.

Effects of g-Jitter on Diffusion in Binary Liquids

NASA Technical Reports Server (NTRS)

Duval, Walter M. B.

1999-01-01

The microgravity environment offers the potential to measure the binary diffusion coefficients in liquids without the masking effects introduced by buoyancy-induced flows due to Earth s gravity. However, the background g-jitter (vibrations from the shuttle, onboard machinery, and crew) normally encountered in many shuttle experiments may alter the benefits of the microgravity environment and introduce vibrations that could offset its intrinsic advantages. An experiment during STS-85 (August 1997) used the Microgravity Vibration Isolation Mount (MIM) to isolate and introduce controlled vibrations to two miscible liquids inside a cavity to study the effects of g-jitter on liquid diffusion. Diffusion in a nonhomogeneous liquid system is caused by a nonequilibrium condition that results in the transport of mass (dispersion of the different kinds of liquid molecules) to approach equilibrium. The dynamic state of the system tends toward equilibrium such that the system becomes homogeneous. An everyday example is the mixing of cream and coffee (a nonhomogeneous system) via stirring. The cream diffuses into the coffee, thus forming a homogeneous system. At equilibrium the system is said to be mixed. However, during stirring, simple observations show complex flow field dynamics-stretching and folding of material interfaces, thinning of striation thickness, self-similar patterns, and so on. This example illustrates that, even though mixing occurs via mass diffusion, stirring to enhance transport plays a major role. Stirring can be induced either by mechanical means (spoon or plastic stirrer) or via buoyancy-induced forces caused by Earth s gravity. Accurate measurements of binary diffusion coefficients are often inhibited by buoyancy-induced flows. The microgravity environment minimizes the effect of buoyancy-induced flows and allows the true diffusion limit to be achieved. One goal of this experiment was to show that the microgravity environment suppresses buoyancy

Simulation of Combustion Systems with Realistic g-jitter

NASA Technical Reports Server (NTRS)

Mell, William E.; McGrattan, Kevin B.; Baum, Howard R.

2003-01-01

In this project a transient, fully three-dimensional computer simulation code was developed to simulate the effects of realistic g-jitter on a number of combustion systems. The simulation code is capable of simulating flame spread on a solid and nonpremixed or premixed gaseous combustion in nonturbulent flow with simple combustion models. Simple combustion models were used to preserve computational efficiency since this is meant to be an engineering code. Also, the use of sophisticated turbulence models was not pursued (a simple Smagorinsky type model can be implemented if deemed appropriate) because if flow velocities are large enough for turbulence to develop in a reduced gravity combustion scenario it is unlikely that g-jitter disturbances (in NASA's reduced gravity facilities) will play an important role in the flame dynamics. Acceleration disturbances of realistic orientation, magnitude, and time dependence can be easily included in the simulation. The simulation algorithm was based on techniques used in an existing large eddy simulation code which has successfully simulated fire dynamics in complex domains. A series of simulations with measured and predicted acceleration disturbances on the International Space Station (ISS) are presented. The results of this series of simulations suggested a passive isolation system and appropriate scheduling of crew activity would provide a sufficiently "quiet" acceleration environment for spherical diffusion flames.

Wide tracking range, auto ranging, low jitter phase lock loop for swept and fixed frequency systems

DOEpatents

Kerner, Thomas M.

2001-01-01

The present invention provides a wide tracking range phase locked loop (PLL) circuit that achieves minimal jitter in a recovered clock signal, regardless of the source of the jitter (i.e. whether it is in the source or the transmission media). The present invention PLL has automatic harmonic lockout detection circuitry via a novel lock and seek control logic in electrical communication with a programmable frequency discriminator and a code balance detector. (The frequency discriminator enables preset of a frequency window of upper and lower frequency limits to derive a programmable range within which signal acquisition is effected. The discriminator works in combination with the code balance detector circuit to minimize the sensitivity of the PLL circuit to random data in the data stream). In addition, the combination of a differential loop integrator with the lock and seek control logic obviates a code preamble and guarantees signal acquisition without harmonic lockup. An adaptive cable equalizer is desirably used in combination with the present invention PLL to recover encoded transmissions containing a clock and/or data. The equalizer automatically adapts to equalize short haul cable lengths of coaxial and twisted pair cables or wires and provides superior jitter performance itself. The combination of the equalizer with the present invention PLL is desirable in that such combination permits the use of short haul wires without significant jitter.

Influence of G-jitter on the characteristics of a non-premixed flame: Experimental approach

NASA Astrophysics Data System (ADS)

Joulain, Pierre; Cordeiro, Pierre; Rouvreau, Sébastien; Legros, Guillaume; Fuentes, Andres; Torero, José L.

2005-03-01

The combustion of a flat plate in a boundary layer under microgravity conditions, which was first described by Emmons, is studied using a gas burner. Magnitude of injection and blowing velocities are chosen to be characteristic of pyrolyzing velocity of solid fuels, and of ventilation systems in space stations. These velocities are about 0.1 m/s for oxidiser flow and 0.004m/s for fuel flow. In this configuration, flame layout results from a coupled interaction between oxidiser flow, fuel flow and thermal expansion. Influences of these parameters are studied experimentally by means of flame length and standoff distance measurements using CH* chemiluminescence's and visible emission of the flame. Flow was also studied with Particle Image Velocimetry (PIV). Inert flows, with and without injection, and reacting flow in a microgravity environment were considered to distinguish aerodynamic from thermal effect. Thermal expansion effects have been shown by means of the acceleration of oxidiser flow. Three-dimensional effects, which are strongly marked for high injection velocities were studied. Three-dimensional tools adaptability to parabolic flights particular conditions were of concern. Flame sensitivity to g-jitters was investigated according to g-jitters frequency and range involved by parabolic flights. It appears that flame location (standoff distance), flame characteristics (length, thickness, brightness) and the aerodynamic field of the low velocity reacting flow are very much affected by the fluctuation of the gravity level or g-jitter. The lower the g-jitter frequency is, the higher the perturbation. Consequently it is difficult to perform relevant experiments for a main flow velocity lower than 0.05m/s. DNS calculations confirm the present observations, but most of the results are presented elsewhere.

Low-sensitivity H ∞ filter design for linear delta operator systems with sampling time jitter

NASA Astrophysics Data System (ADS)

Guo, Xiang-Gui; Yang, Guang-Hong

2012-04-01

This article is concerned with the problem of designing H ∞ filters for a class of linear discrete-time systems with low-sensitivity to sampling time jitter via delta operator approach. Delta-domain model is used to avoid the inherent numerical ill-condition resulting from the use of the standard shift-domain model at high sampling rates. Based on projection lemma in combination with the descriptor system approach often used to solve problems related to delay, a novel bounded real lemma with three slack variables for delta operator systems is presented. A sensitivity approach based on this novel lemma is proposed to mitigate the effects of sampling time jitter on system performance. Then, the problem of designing a low-sensitivity filter can be reduced to a convex optimisation problem. An important consideration in the design of correlation filters is the optimal trade-off between the standard H ∞ criterion and the sensitivity of the transfer function with respect to sampling time jitter. Finally, a numerical example demonstrating the validity of the proposed design method is given.

Note: A new method for directly reducing the sampling jitter noise of the digital phasemeter

NASA Astrophysics Data System (ADS)

Liang, Yu-Rong

2018-03-01

The sampling jitter noise is one non-negligible noise source of the digital phasemeter used for space gravitational wave detection missions. This note provides a new method for directly reducing the sampling jitter noise of the digital phasemeter, by adding a dedicated signal of which the frequency, amplitude, and initial phase should be pre-set. In contrast to the phase correction using the pilot-tone in the work of Burnett, Gerberding et al., Liang et al., Ales et al., Gerberding et al., and Ware et al. [M.Sc. thesis, Luleå University of Technology, 2010; Classical Quantum Gravity 30, 235029 (2013); Rev. Sci. Instrum. 86, 016106 (2015); Rev. Sci. Instrum. 86, 084502 (2015); Rev. Sci. Instrum. 86, 074501 (2015); and Proceedings of the Earth Science Technology Conference (NASA, USA, 2006)], the new method is intrinsically additive noise suppression. The experiment results validate that the new method directly reduces the sampling jitter noise without data post-processing and provides the same phase measurement noise level (10-6 rad/Hz1/2 at 0.1 Hz) as the pilot-tone correction.

Linear Polarization, Circular Polarization, and Depolarization of Gamma-ray Bursts: A Simple Case of Jitter Radiation

NASA Astrophysics Data System (ADS)

Mao, Jirong; Wang, Jiancheng

2017-04-01

Linear and circular polarizations of gamma-ray bursts (GRBs) have been detected recently. We adopt a simplified model to investigate GRB polarization characteristics in this paper. A compressed two-dimensional turbulent slab containing stochastic magnetic fields is considered, and jitter radiation can produce the linear polarization under this special magnetic field topology. Turbulent Faraday rotation measure (RM) of this slab makes strong wavelength-dependent depolarization. The jitter photons can also scatter with those magnetic clumps inside the turbulent slab, and a nonzero variance of the Stokes parameter V can be generated. Furthermore, the linearly and circularly polarized photons in the optical and radio bands may suffer heavy absorptions from the slab. Thus we consider the polarized jitter radiation transfer processes. Finally, we compare our model results with the optical detections of GRB 091018, GRB 121024A, and GRB 131030A. We suggest simultaneous observations of GRB multi-wavelength polarization in the future.

The effect of jitter on the performance of space coherent optical communication system with Costas loop

NASA Astrophysics Data System (ADS)

Li, Xin; Hong, Yifeng; Wang, Jinfang; Liu, Yang; Sun, Xun; Li, Mi

2018-01-01

Numerous communication techniques and optical devices successfully applied in space optical communication system indicates a good portability of it. With this good portability, typical coherent demodulation technique of Costas loop can be easily adopted in space optical communication system. As one of the components of pointing error, the effect of jitter plays an important role in the communication quality of such system. Here, we obtain the probability density functions (PDF) of different jitter degrees and explain their essential effect on the bit error rate (BER) space optical communication system. Also, under the effect of jitter, we research the bit error rate of space coherent optical communication system using Costas loop with different system parameters of transmission power, divergence angle, receiving diameter, avalanche photodiode (APD) gain, and phase deviation caused by Costas loop. Through a numerical simulation of this kind of communication system, we demonstrate the relationship between the BER and these system parameters, and some corresponding methods of system optimization are presented to enhance the communication quality.

Linear Polarization, Circular Polarization, and Depolarization of Gamma-ray Bursts: A Simple Case of Jitter Radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mao, Jirong; Wang, Jiancheng, E-mail: jirongmao@mail.ynao.ac.cn

Linear and circular polarizations of gamma-ray bursts (GRBs) have been detected recently. We adopt a simplified model to investigate GRB polarization characteristics in this paper. A compressed two-dimensional turbulent slab containing stochastic magnetic fields is considered, and jitter radiation can produce the linear polarization under this special magnetic field topology. Turbulent Faraday rotation measure (RM) of this slab makes strong wavelength-dependent depolarization. The jitter photons can also scatter with those magnetic clumps inside the turbulent slab, and a nonzero variance of the Stokes parameter V can be generated. Furthermore, the linearly and circularly polarized photons in the optical and radiomore » bands may suffer heavy absorptions from the slab. Thus we consider the polarized jitter radiation transfer processes. Finally, we compare our model results with the optical detections of GRB 091018, GRB 121024A, and GRB 131030A. We suggest simultaneous observations of GRB multi-wavelength polarization in the future.« less

Reorientation of rotating fluid in microgravity environment with and without gravity jitters

NASA Technical Reports Server (NTRS)

Hung, R. J.; Lee, C. C.; Shyu, K. L.

1990-01-01

In a spacecraft design, the requirements of settled propellant are different for tank pressurization, engine restart, venting, or propellant transfer. The requirement to settle or to position liquid fuel over the outlet end of the spacecraft propellant tank prior main engine restart poses a microgravity fluid behavior problem. In this paper, the dynamical behavior of liquid propellant, fluid reorientation, and propellant resettling have been carried out through the execution of supercomputer CRAY X-MP to simulate the fluid management in a microgravity environment. Results show that the resettlement of fluid can be accomplished more efficiently for fluid in rotating tank than in nonrotating tank, and also better performance for gravity jitters imposed on fluid settlement than without gravity jitters based on the amount of time needed to carry out resettlement period of time between the initiation and termination of geysering.

Attitude determination for high-accuracy submicroradian jitter pointing on space-based platforms

NASA Astrophysics Data System (ADS)

Gupta, Avanindra A.; van Houten, Charles N.; Germann, Lawrence M.

1990-10-01

A description of the requirement definition process is given for a new wideband attitude determination subsystem (ADS) for image motion compensation (IMC) systems. The subsystem consists of either lateral accelerometers functioning in differential pairs or gas-bearing gyros for high-frequency sensors using CCD-based star trackers for low-frequency sensors. To minimize error the sensor signals are combined so that the mixing filter does not allow phase distortion. The two ADS models are introduced in an IMC simulation to predict measurement error, correction capability, and residual image jitter for a variety of system parameters. The IMC three-axis testbed is utilized to simulate an incoming beam in inertial space. Results demonstrate that both mechanical and electronic IMC meet the requirements of image stabilization for space-based observation at submicroradian-jitter levels. Currently available technology may be employed to implement IMC systems.

Superior bit error rate and jitter due to improved switching field distribution in exchange spring magnetic recording media

PubMed Central

Suess, D.; Fuger, M.; Abert, C.; Bruckner, F.; Vogler, C.

2016-01-01

We report two effects that lead to a significant reduction of the switching field distribution in exchange spring media. The first effect relies on a subtle mechanism of the interplay between exchange coupling between soft and hard layers and anisotropy that allows significant reduction of the switching field distribution in exchange spring media. This effect reduces the switching field distribution by about 30% compared to single-phase media. A second effect is that due to the improved thermal stability of exchange spring media over single-phase media, the jitter due to thermal fluctuation is significantly smaller for exchange spring media than for single-phase media. The influence of this overall improved switching field distribution on the transition jitter in granular recording and the bit error rate in bit-patterned magnetic recording is discussed. The transition jitter in granular recording for a distribution of Khard values of 3% in the hard layer, taking into account thermal fluctuations during recording, is estimated to be a = 0.78 nm, which is similar to the best reported calculated jitter in optimized heat-assisted recording media. PMID:27245287

On the effects of phase jitter on QPSK lock detection

NASA Technical Reports Server (NTRS)

Mileant, A.; Hinedi, S.

1993-01-01

The performance of a QPSK (quadrature phase-shift keying) lock detector is described, taking into account the degradation due to carrier phase jitter. Such an analysis is necessary for accurate performance prediction purposes in scenarios where both the loop SNR is low and the estimation period is short. The derived formulas are applicable to several QPSK loops and are verified using computer simulations.

Data Reduction of Jittered Infrared Images Using the ORAC Pipeline

NASA Astrophysics Data System (ADS)

Currie, Malcolm; Wright, Gillian; Bridger, Alan; Economou, Frossie

We relate our experiences using the ORAC data reduction pipeline for jittered images of stars and galaxies. The reduction recipes currently combine applications from several Starlink packages with intelligent Perl recipes to cater to UKIRT data. We describe the recipes and some of the algorithms used, and compare the quality of the resultant mosaics and photometry with the existing facilities.

ISAAC Photometric Comparison of ECLIPSE Jitter and the ORAC-DR Equivalent Recipe for ISAAC

NASA Astrophysics Data System (ADS)

Currie, M. J.

2005-12-01

Motivated by a request from astronomers demanding accurate and consistent infrared photometry, I compare the photometry and quality of mosaics generated by the ECLIPSE jitter task and the ORAC-DR JITTER_SELF_FLAT recipe in two fields. The current (v4.9.0) ECLIPSE produces photometry a few percent fainter than ORAC-DR; the systematic trend with magnitude seen in v4.4.1 is now removed. Random errors arising from poor flat-fielding are not resolved. ECLIPSE generates noisier mosaics; ORAC-DR has poorer bias removal in crowded fields and defaults to larger mosaics. ORAC-DR runs a few times slower than ECLIPSE, but its recipe development is measured in weeks, not years.

Acquisition and Initial Analysis of H+- and H--Beam Centroid Jitter at LANSCE

NASA Astrophysics Data System (ADS)

Gilpatrick, J. D.; Bitteker, L.; Gulley, M. S.; Kerstiens, D.; Oothoudt, M.; Pillai, C.; Power, J.; Shelley, F.

2006-11-01

During the 2005 Los Alamos Neutron Science Center (LANSCE) beam runs, beam current and centroid-jitter data were observed, acquired, analyzed, and documented for both the LANSCE H+ and H- beams. These data were acquired using three beam position monitors (BPMs) from the 100-MeV Isotope Production Facility (IPF) beam line and three BPMs from the Switchyard transport line at the end of the LANSCE 800-MeV linac. The two types of data acquired, intermacropulse and intramacropulse, were analyzed for statistical and frequency characteristics as well as various other correlations including comparing their phase-space like characteristics in a coordinate system of transverse angle versus transverse position. This paper will briefly describe the measurements required to acquire these data, the initial analysis of these jitter data, and some interesting dilemmas these data presented.

A compact, low jitter, nanosecond rise time, high voltage pulse generator with variable amplitude.

PubMed

Mao, Jiubing; Wang, Xin; Tang, Dan; Lv, Huayi; Li, Chengxin; Shao, Yanhua; Qin, Lan

2012-07-01

In this paper, a compact, low jitter, nanosecond rise time, command triggered, high peak power, gas-switch pulse generator system is developed for high energy physics experiment. The main components of the system are a high voltage capacitor, the spark gap switch and R = 50 Ω load resistance built into a structure to obtain a fast high power pulse. The pulse drive unit, comprised of a vacuum planar triode and a stack of avalanche transistors, is command triggered by a single or multiple TTL (transistor-transistor logic) level pulses generated by a trigger pulse control unit implemented using the 555 timer circuit. The control unit also accepts user input TTL trigger signal. The vacuum planar triode in the pulse driving unit that close the first stage switches is applied to drive the spark gap reducing jitter. By adjusting the charge voltage of a high voltage capacitor charging power supply, the pulse amplitude varies from 5 kV to 10 kV, with a rise time of <3 ns and the maximum peak current up to 200 A (into 50 Ω). The jitter of the pulse generator system is less than 1 ns. The maximum pulse repetition rate is set at 10 Hz that limited only by the gas-switch and available capacitor recovery time.

An examination of anticipated g-jitter on Space Station and its effects on materials processes

NASA Technical Reports Server (NTRS)

Nelson, Emily S.

1994-01-01

This study is concerned with the effects of g-jitter, the residual acceleration aboard spacecraft, on selected classes of materials processes. In particular, the anticipated acceleration environment aboard Space Station Freedom (SSF) and its potential effects are analyzed, but the topic is covered with a sufficient level of generality as to apply to other processes and to other vehicles as well. Some of the key findings of this study include: The present acceleration specifications for SSF are inadequate to assure a quality level low-g environment. The local g vector orientation is an extremely sensitive parameter for certain key processes, but can not be controlled to within the desired tolerance. Therefore, less emphasis should be placed upon achieving a tight control of SSF attitude, but more emphasis should be focused on reducing the overall level of the g-jitter magnitude. Melt-based crystal growth may not be successfully processed in the relatively noisy environment of a large inhabited space structure. Growth from vapor or from solution appears more favorable. A smaller space structure and/or a free flyer can provide better alternatives in terms of g-jitter considerations. A high priority (including budgetary) should be given to coordinated efforts among researchers, SSF designers, and equipment contractors, to develop practical experiment-specific sensitivity requirements. Combined focused numerical simulations and experiments with well-resolved acceleration measurements should be vigorously pursued for developing reliable experiment-specific sensitivity data. Appendices provide an extensive cross-referenced bibliography, a discussion of the merits offered by g-jitter analysis techniques, as well as definitions of relevant nondimensional quantities and a brief description of available accelerometry hardware.

Note: Design and implementation of a home-built imaging system with low jitter for cold atom experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hachtel, A. J.; Gillette, M. C.; Clements, E. R.

A novel home-built system for imaging cold atom samples is presented using a readily available astronomy camera which has the requisite sensitivity but no timing-control. We integrate the camera with LabVIEW achieving fast, low-jitter imaging with a convenient user-defined interface. We show that our system takes precisely timed millisecond exposures and offers significant improvements in terms of system jitter and readout time over previously reported home-built systems. Our system rivals current commercial “black box” systems in performance and user-friendliness.

A 250 MHz, high power mode-locked Nd:GdVO4 oscillator with low timing jitter under 879 nm direct pumping

NASA Astrophysics Data System (ADS)

Zhang, F. F.; Zuo, J. W.; Wang, Z. M.; Yang, J.; Cheng, H. L.; Zong, N.; Yang, F.; Peng, Q. J.; Xu, Z. Y.

2013-04-01

We developed a high power mode-locked Nd:GdVO4 oscillator with low timing jitter directly pumped by an 879 nm diode. Under the absorbed pump power of 13.8 W, a maximum output power of 5.68 W at 1063 nm was obtained with a repetition rate of ˜250 MHz, corresponding to a slope efficiency of 78.7%. The measured pulse width and root mean square timing jitter at the output power of 5.35 W were 7.4 ps and 286 fs, respectively. To the best of our knowledge, this is the highest output power for a picosecond Nd:GdVO4 oscillator with low timing jitter.

G-jitter Effects on Transport and Pattern Formation

NASA Technical Reports Server (NTRS)

Schatz, Michael F.

2003-01-01

The research performed under this grant has led to an number of new insights into two general categories of fluid flows in the presence of time-dependent acceleration, as outlined briefly below. These results have been widely communicated in the scientific community through seven presentations at international conferences (4 invited, 3 contributed), five published papers (4 journal articles and 1 conference proceeding), and images from the research featured on the cover of all 2003 editions of the research journal, Nonlinearity. The work performed under this proposal also contained a substantial educational component by contributed significantly to the scientific training of one postdoctoral associate, one Ph.D. student and five undergraduate researchers. One main area of focus in this research was convective flow with time-dependent acceleration. Convection is one class of behavior that can arise from g-jitter effects. Our research focused on studies of Rayleigh-Benard system, which is an important model for understanding thermal convection; studies of this problem in the presence of acceleration modulations provided insight into the nature of g-jitter induced flow and of the effects of modulation and noise on non-equilibrium pattern formation. Our experiments on vertically vibrated Rayleigh-Benard convection demonstrated the existence of two classes of pure flow patterns (synchronous & subharmonic) patterns) that had long been predicted by theory but never before observed experimentally. Detailed studies of ranges of parameters where both classes of patterns exist simultaneously led to the discovery of a new type of patterns (called superlattices) in systems driven out of thermodynamic equilibrium.

100 km differential phase shift quantum key distribution experiment with low jitter up-conversion detectors

NASA Astrophysics Data System (ADS)

Diamanti, Eleni; Takesue, Hiroki; Langrock, Carsten; Fejer, M. M.; Yamamoto, Yoshihisa

2006-12-01

We present a quantum key distribution experiment in which keys that were secure against all individual eavesdropping attacks allowed by quantum mechanics were distributed over 100 km of optical fiber. We implemented the differential phase shift quantum key distribution protocol and used low timing jitter 1.55 µm single-photon detectors based on frequency up-conversion in periodically poled lithium niobate waveguides and silicon avalanche photodiodes. Based on the security analysis of the protocol against general individual attacks, we generated secure keys at a practical rate of 166 bit/s over 100 km of fiber. The use of the low jitter detectors also increased the sifted key generation rate to 2 Mbit/s over 10 km of fiber.

Gigahertz repetition rate, sub-femtosecond timing jitter optical pulse train directly generated from a mode-locked Yb:KYW laser.

PubMed

Yang, Heewon; Kim, Hyoji; Shin, Junho; Kim, Chur; Choi, Sun Young; Kim, Guang-Hoon; Rotermund, Fabian; Kim, Jungwon

2014-01-01

We show that a 1.13 GHz repetition rate optical pulse train with 0.70 fs high-frequency timing jitter (integration bandwidth of 17.5 kHz-10 MHz, where the measurement instrument-limited noise floor contributes 0.41 fs in 10 MHz bandwidth) can be directly generated from a free-running, single-mode diode-pumped Yb:KYW laser mode-locked by single-wall carbon nanotube-coated mirrors. To our knowledge, this is the lowest-timing-jitter optical pulse train with gigahertz repetition rate ever measured. If this pulse train is used for direct sampling of 565 MHz signals (Nyquist frequency of the pulse train), the jitter level demonstrated would correspond to the projected effective-number-of-bit of 17.8, which is much higher than the thermal noise limit of 50 Ω load resistance (~14 bits).

Design of optical axis jitter control system for multi beam lasers based on FPGA

NASA Astrophysics Data System (ADS)

Ou, Long; Li, Guohui; Xie, Chuanlin; Zhou, Zhiqiang

2018-02-01

A design of optical axis closed-loop control system for multi beam lasers coherent combining based on FPGA was introduced. The system uses piezoelectric ceramics Fast Steering Mirrors (FSM) as actuator, the Fairfield spot detection of multi beam lasers by the high speed CMOS camera for optical detecting, a control system based on FPGA for real-time optical axis jitter suppression. The algorithm for optical axis centroid detecting and PID of anti-Integral saturation were realized by FPGA. Optimize the structure of logic circuit by reuse resource and pipeline, as a result of reducing logic resource but reduced the delay time, and the closed-loop bandwidth increases to 100Hz. The jitter of laser less than 40Hz was reduced 40dB. The cost of the system is low but it works stably.

Stochastic mechanical model of vocal folds for producing jitter and for identifying pathologies through real voices.

PubMed

Cataldo, E; Soize, C

2018-06-06

Jitter, in voice production applications, is a random phenomenon characterized by the deviation of the glottal cycle length with respect to a mean value. Its study can help in identifying pathologies related to the vocal folds according to the values obtained through the different ways to measure it. This paper aims to propose a stochastic model, considering three control parameters, to generate jitter based on a deterministic one-mass model for the dynamics of the vocal folds and to identify parameters from the stochastic model taking into account real voice signals experimentally obtained. To solve the corresponding stochastic inverse problem, the cost function used is based on the distance between probability density functions of the random variables associated with the fundamental frequencies obtained by the experimental voices and the simulated ones, and also on the distance between features extracted from the voice signals, simulated and experimental, to calculate jitter. The results obtained show that the model proposed is valid and some samples of voices are synthesized considering the identified parameters for normal and pathological cases. The strategy adopted is also a novelty and mainly because a solution was obtained. In addition to the use of three parameters to construct the model of jitter, it is the discussion of a parameter related to the bandwidth of the power spectral density function of the stochastic process to measure the quality of the signal generated. A study about the influence of all the main parameters is also performed. The identification of the parameters of the model considering pathological cases is maybe of all novelties introduced by the paper the most interesting. Copyright © 2018 Elsevier Ltd. All rights reserved.

Dynamic/Jitter Assessment of Multiple Potential HabEx Structural Designs

NASA Technical Reports Server (NTRS)

Knight, J. Brent; Stahl, H. Philip; Singleton, Andrew William; Hunt, Ronald A.; Therrell, Melissa F.; Caldwell, Mary Kathryn; Garcia, Jay Clarke

2017-01-01

The 2020 Decadal Survey in Astronomy and Astrophysics will assess candidate large missions to follow James Webb Space Telescope (JWST) and Wide Field Infrared Space Telescope (WFIRST). One candidate mission is the Habitable ExoPlanet Imaging Mission (HabEx). This presentation describes two HabEx structural designs and results from structural dynamic analyses performed to predict Primary Mirror (PM) Secondary Mirror (SM) Line of Site (LOS) stability (jitter) due to Reaction Wheel Assembly (RWA) vibrations.

Removal of jitter noise in 3D shape recovery from image focus by using Kalman filter.

PubMed

Jang, Hoon-Seok; Muhammad, Mannan Saeed; Choi, Tae-Sun

2018-02-01

In regard to Shape from Focus, one critical factor impacting system application is mechanical vibration of the translational stage causing jitter noise along the optical axis. This noise is not detectable by simply observing the image. However, when focus measures are applied, inaccuracies in the depth occur. In this article, jitter noise and focus curves are modeled by Gaussian distribution and quadratic function, respectively. Then Kalman filter is designed and applied to eliminate this noise in the focus curves, as a post-processing step after the focus measure application. Experiments are implemented with simulated objects and real objects to show usefulness of proposed algorithm. © 2017 Wiley Periodicals, Inc.

Jitter reduction of a reaction wheel by management of angular momentum using magnetic torquers in nano- and micro-satellites

NASA Astrophysics Data System (ADS)

Inamori, Takaya; Wang, Jihe; Saisutjarit, Phongsatorn; Nakasuka, Shinichi

2013-07-01

Nowadays, nano- and micro-satellites, which are smaller than conventional large satellites, provide access to space to many satellite developers, and they are attracting interest as an application of space development because development is possible over shorter time period at a lower cost. In most of these nano- and micro-satellite missions, the satellites generally must meet strict attitude requirements for obtaining scientific data under strict constraints of power consumption, space, and weight. In many satellite missions, the jitter of a reaction wheel degrades the performance of the mission detectors and attitude sensors; therefore, jitter should be controlled or isolated to reduce its effect on sensor devices. In conventional standard-sized satellites, tip-tilt mirrors (TTMs) and isolators are used for controlling or isolating the vibrations from reaction wheels; however, it is difficult to use these devices for nano- and micro-satellite missions under the strict power, space, and mass constraints. In this research, the jitter of reaction wheels is reduced by using accurate sensors, small reaction wheels, and slow rotation frequency reaction wheel instead of TTMs and isolators. The objective of a reaction wheel in many satellite missions is the management of the satellite's angular momentum, which increases because of attitude disturbances. If the magnitude of the disturbance is reduced in orbit or on the ground, the magnitude of the angular momentum that the reaction wheels gain from attitude disturbances in orbit becomes smaller; therefore, satellites can stabilize their attitude using only smaller reaction wheels or slow rotation speed, which cause relatively smaller vibration. In nano- and micro-satellite missions, the dominant attitude disturbance is a magnetic torque, which can be cancelled by using magnetic actuators. With the magnetic compensation, the satellite reduces the angular momentum that the reaction wheels gain, and therefore, satellites do

Voice Loudness and Gender Effects on Jitter and Shimmer in Healthy Adults

ERIC Educational Resources Information Center

Brockmann, Meike; Storck, Claudio; Carding, Paul N.; Drinnan, Michael J.

2008-01-01

Purpose: The aim of this study was to investigate voice loudness and gender effects on jitter and shimmer in healthy young adults because previous descriptions have been inconsistent. Method: Fifty-seven healthy adults (28 women, 29 men) aged 20-40 years were included in this cross-sectional single-cohort study. Three phonations of /a/ at soft,…

All fiber-coupled, long-term stable timing distribution for free-electron lasers with few-femtosecond jitter

PubMed Central

Şafak, K.; Xin, M.; Callahan, P. T.; Peng, M. Y.; Kärtner, F. X.

2015-01-01

We report recent progress made in a complete fiber-optic, high-precision, long-term stable timing distribution system for synchronization of next generation X-ray free-electron lasers. Timing jitter characterization of the master laser shows less than 170-as RMS integrated jitter for frequencies above 10 kHz, limited by the detection noise floor. Timing stabilization of a 3.5-km polarization-maintaining fiber link is successfully achieved with an RMS drift of 3.3 fs over 200 h of operation using all fiber-coupled elements. This all fiber-optic implementation will greatly reduce the complexity of optical alignment in timing distribution systems and improve the overall mechanical and timing stability of the system. PMID:26798814

Pointing and Jitter Control for the USNA Multi-Beam Combining System

DTIC Science & Technology

2013-05-10

previous work, an adaptive H-infinity optimal controller has been developed to control a single beam using a beam position detector for feedback... turbulence and airborne particles, platform jitter, lack of feedback from the target , and current laser technology represent just a few of these...lasers. Solid state lasers, however, cannot currently provide high enough power levels to destroy a target using a single beam. On solid-state

Low-jitter high-power thyristor array pulse driver and generator

DOEpatents

Hanks, Roy L.

2002-01-01

A method and apparatus for generating low-jitter, high-voltage and high-current pulses for driving low impedance loads such as detonator fuses uses a MOSFET driver which, when triggered, discharges a high-voltage pre-charged capacitor into the primary of a toroidal current-multiplying transformer with multiple isolated secondary windings. The secondary outputs are suitable for driving an array of thyristors that discharge a precharged high-voltage capacitor and thus generating the required high-voltage and high-current pulse.

Dissociation of rapid response learning and facilitation in perceptual and conceptual networks of person recognition.

PubMed

Valt, Christian; Klein, Christoph; Boehm, Stephan G

2015-08-01

Repetition priming is a prominent example of non-declarative memory, and it increases the accuracy and speed of responses to repeatedly processed stimuli. Major long-hold memory theories posit that repetition priming results from facilitation within perceptual and conceptual networks for stimulus recognition and categorization. Stimuli can also be bound to particular responses, and it has recently been suggested that this rapid response learning, not network facilitation, provides a sound theory of priming of object recognition. Here, we addressed the relevance of network facilitation and rapid response learning for priming of person recognition with a view to advance general theories of priming. In four experiments, participants performed conceptual decisions like occupation or nationality judgments for famous faces. The magnitude of rapid response learning varied across experiments, and rapid response learning co-occurred and interacted with facilitation in perceptual and conceptual networks. These findings indicate that rapid response learning and facilitation in perceptual and conceptual networks are complementary rather than competing theories of priming. Thus, future memory theories need to incorporate both rapid response learning and network facilitation as individual facets of priming. © 2014 The British Psychological Society.

Jitter-correction for IR/UV-XUV pump-probe experiments at the FLASH free-electron laser

DOE PAGES

Savelyev, Evgeny; Boll, Rebecca; Bomme, Cedric; ...

2017-04-10

In pump-probe experiments employing a free-electron laser (FEL) in combination with a synchronized optical femtosecond laser, the arrival-time jitter between the FEL pulse and the optical laser pulse often severely limits the temporal resolution that can be achieved. Here, we present a pump-probe experiment on the UV-induced dissociation of 2,6-difluoroiodobenzene C 6H 3F 2I) molecules performed at the FLASH FEL that takes advantage of recent upgrades of the FLASH timing and synchronization system to obtain high-quality data that are not limited by the FEL arrival-time jitter. Here, we discuss in detail the necessary data analysis steps and describe the originmore » of the time-dependent effects in the yields and kinetic energies of the fragment ions that we observe in the experiment.« less

Problems in Microgravity Fluid Mechanics: G-Jitter Convection

NASA Technical Reports Server (NTRS)

Homsy, G. M.

2005-01-01

This is the final report on our NASA grant, Problems in Microgravity Fluid Mechanics NAG3-2513: 12/14/2000 - 11/30/2003, extended through 11/30/2004. This grant was made to Stanford University and then transferred to the University of California at Santa Barbara when the PI relocated there in January 2001. Our main activity has been to conduct both experimental and theoretical studies of instabilities in fluids that are relevant to the microgravity environment, i.e. those that do not involve the action of buoyancy due to a steady gravitational field. Full details of the work accomplished under this grant are given below. Our work has focused on: (i) Theoretical and computational studies of the effect of g-jitter on instabilities of convective states where the convection is driven by forces other than buoyancy (ii) Experimental studies of instabilities during displacements of miscible fluid pairs in tubes, with a focus on the degree to which these mimic those found in immiscible fluids. (iii) Theoretical and experimental studies of the effect of time dependent electrohydrodynamic forces on chaotic advection in drops immersed in a second dielectric liquid. Our objectives are to acquire insight and understanding into microgravity fluid mechanics problems that bear on either fundamental issues or applications in fluid physics. We are interested in the response of fluids to either a fluctuating acceleration environment or to forces other than gravity that cause fluid mixing and convection. We have been active in several general areas.

Femtosecond timing-jitter between photo-cathode laser and ultra-short electron bunches by means of hybrid compression

NASA Astrophysics Data System (ADS)

Pompili, R.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Castorina, G.; Chiadroni, E.; Cianchi, A.; Croia, M.; Di Giovenale, D.; Ferrario, M.; Filippi, F.; Gallo, A.; Gatti, G.; Giorgianni, F.; Giribono, A.; Li, W.; Lupi, S.; Mostacci, A.; Petrarca, M.; Piersanti, L.; Di Pirro, G.; Romeo, S.; Scifo, J.; Shpakov, V.; Vaccarezza, C.; Villa, F.

2016-08-01

The generation of ultra-short electron bunches with ultra-low timing-jitter relative to the photo-cathode (PC) laser has been experimentally proved for the first time at the SPARC_LAB test-facility (INFN-LNF, Frascati) exploiting a two-stage hybrid compression scheme. The first stage employs RF-based compression (velocity-bunching), which shortens the bunch and imprints an energy chirp on it. The second stage is performed in a non-isochronous dogleg line, where the compression is completed resulting in a final bunch duration below 90 fs (rms). At the same time, the beam arrival timing-jitter with respect to the PC laser has been measured to be lower than 20 fs (rms). The reported results have been validated with numerical simulations.

Young Nearby Suns and Stellar Jitter Dependence on Age

NASA Astrophysics Data System (ADS)

Cabrera, Nicole; White, Russel; Delfosse, Xavier; Noah Quinn, Samuel; Latham, David W.

2015-01-01

Finding the nearest young planets offers the most direct way to improve our understanding of how planets form, how they migrate, and how they evolve. However, most radial velocity (RV) surveys have avoided young stars because of their problematic characteristics, including high levels of stellar activity. Recent advancements in infrared (IR) detectors as well as wavelength calibration methods have provided new ways of pursuing high-precision RV measurements of young stars. While this work has been successfully applied to many young late-K and M dwarfs, much less RV work has been done on young Sun-like stars, with the very recent exception of adolescent stars (~600 Myr) in open clusters. In order to better understand the dynamical and structural forces that shaped our own Solar system, we must begin to explore the more massive realm of Sun-like stars.We present precision optical radial velocity data of 5 young, nearby, Sun-like stars in AB Dor and assess our ability to detect young planets with current spectroscopic methods. The data were obtained with the TRES spectrograph on the 1.5-m Tillinghast Reflector at the Fred L. Whipple Observatory and with SOPHIE on the 1.95 m Telescope at the Observatoire de Haute Provence. We obtained a RV precision of ~8 m/s with TRES and ~7 m/s precision with SOPHIE; average observed dispersions are 38 m/s and 33 m/s, respectively. We combine our results with spectroscopic data of Sun-like stars spanning a broad range of youthful ages (< 1 Gyr) from the literature to investigate the relationship between stellar jitter and stellar age. The results suggest that the jitter of Sun-like stars decreases below 100 m/s for stars older than ~30 Myr, which would enable the discovery of hot Jupiters orbiting these adolescent age stars.

A simple high-voltage high current spark gap with subnanosecond jitter triggered by femtosecond laser filamentation

NASA Astrophysics Data System (ADS)

Arantchouk, L.; Houard, A.; Brelet, Y.; Carbonnel, J.; Larour, J.; André, Y.-B.; Mysyrowicz, A.

2013-04-01

We describe a simple, sturdy, and reliable spark gap operating with air at atmospheric pressure and able to switch currents in excess of 10 kA with sub-nanosecond jitter. The spark gap is remotely triggered by a femtosecond laser filament.

Reliable jitter and shimmer measurements in voice clinics: the relevance of vowel, gender, vocal intensity, and fundamental frequency effects in a typical clinical task.

PubMed

Brockmann, Meike; Drinnan, Michael J; Storck, Claudio; Carding, Paul N

2011-01-01

The aims of this study were to examine vowel and gender effects on jitter and shimmer in a typical clinical voice task while correcting for the confounding effects of voice sound pressure level (SPL) and fundamental frequency (F(0)). Furthermore the relative effect sizes of vowel, gender, voice SPL, and F(0) were assessed, and recommendations for clinical measurements were derived. With this cross-sectional single cohort study, 57 healthy adults (28 women, 29 men) aged 20-40 years were investigated. Three phonations of /a/, /o/, and /i/ at "normal" voice loudness were analyzed using Praat (software). The effects of vowel, gender, voice SPL, and F(0) on jitter and shimmer were assessed using descriptive and inferential (analysis of covariance) statistics. The effect sizes were determined with the eta-squared statistic. Vowels, gender, voice SPL, and F(0), each had significant effects either on jitter or on shimmer, or both. Voice SPL was the most important factor, whereas vowel, gender, and F(0) effects were comparatively small. Because men had systematically higher voice SPL, the gender effects on jitter and shimmer were smaller when correcting for SPL and F(0). Surprisingly, in clinical assessments, voice SPL has the single biggest impact on jitter and shimmer. Vowel and gender effects were clinically important, whereas fundamental frequency had a relatively small influence. Phonations at a predefined voice SPL (80 dB minimum) and vowel (/a/) would enhance measurement reliability. Furthermore, gender-specific thresholds applying these guidelines should be established. However, the efficiency of these measures should be verified and tested with patients. Copyright © 2011 The Voice Foundation. All rights reserved.

A review on high-resolution CMOS delay lines: towards sub-picosecond jitter performance.

PubMed

Abdulrazzaq, Bilal I; Abdul Halin, Izhal; Kawahito, Shoji; Sidek, Roslina M; Shafie, Suhaidi; Yunus, Nurul Amziah Md

2016-01-01

A review on CMOS delay lines with a focus on the most frequently used techniques for high-resolution delay step is presented. The primary types, specifications, delay circuits, and operating principles are presented. The delay circuits reported in this paper are used for delaying digital inputs and clock signals. The most common analog and digitally-controlled delay elements topologies are presented, focusing on the main delay-tuning strategies. IC variables, namely, process, supply voltage, temperature, and noise sources that affect delay resolution through timing jitter are discussed. The design specifications of these delay elements are also discussed and compared for the common delay line circuits. As a result, the main findings of this paper are highlighting and discussing the followings: the most efficient high-resolution delay line techniques, the trade-off challenge found between CMOS delay lines designed using either analog or digitally-controlled delay elements, the trade-off challenge between delay resolution and delay range and the proposed solutions for this challenge, and how CMOS technology scaling can affect the performance of CMOS delay lines. Moreover, the current trends and efforts used in order to generate output delayed signal with low jitter in the sub-picosecond range are presented.

Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter

NASA Astrophysics Data System (ADS)

Martínez-Arnáiz, R.; Maldonado, J.; Montes, D.; Eiroa, C.; Montesinos, B.

2010-09-01

Context. Chromospheric activity produces both photometric and spectroscopic variations that can be mistaken as planets. Large spots crossing the stellar disc can produce planet-like periodic variations in the light curve of a star. These spots clearly affect the spectral line profiles, and their perturbations alter the line centroids creating a radial velocity jitter that might “contaminate” the variations induced by a planet. Precise chromospheric activity measurements are needed to estimate the activity-induced noise that should be expected for a given star. Aims: We obtain precise chromospheric activity measurements and projected rotational velocities for nearby (d ≤ 25 pc) cool (spectral types F to K) stars, to estimate their expected activity-related jitter. As a complementary objective, we attempt to obtain relationships between fluxes in different activity indicator lines, that permit a transformation of traditional activity indicators, i.e., Ca ii H & K lines, to others that hold noteworthy advantages. Methods: We used high resolution (~50 000) echelle optical spectra. Standard data reduction was performed using the IRAF echelle package. To determine the chromospheric emission of the stars in the sample, we used the spectral subtraction technique. We measured the equivalent widths of the chromospheric emission lines in the subtracted spectrum and transformed them into fluxes by applying empirical equivalent width and flux relationships. Rotational velocities were determined using the cross-correlation technique. To infer activity-related radial velocity (RV) jitter, we used empirical relationships between this jitter and the R'_HK index. Results: We measured chromospheric activity, as given by different indicators throughout the optical spectra, and projected rotational velocities for 371 nearby cool stars. We have built empirical relationships among the most important chromospheric emission lines. Finally, we used the measured chromospheric activity

Sub-fs electron bunch generation with sub-10-fs bunch arrival-time jitter via bunch slicing in a magnetic chicane

NASA Astrophysics Data System (ADS)

Zhu, J.; Assmann, R. W.; Dohlus, M.; Dorda, U.; Marchetti, B.

2016-05-01

The generation of ultrashort electron bunches with ultrasmall bunch arrival-time jitter is of vital importance for laser-plasma wakefield acceleration with external injection. We study the production of 100-MeV electron bunches with bunch durations of subfemtosecond (fs) and bunch arrival-time jitters of less than 10 fs, in an S-band photoinjector by using a weak magnetic chicane with a slit collimator. The beam dynamics inside the chicane is simulated by using two codes with different self-force models. The first code separates the self-force into a three-dimensional (3D) quasistatic space-charge model and a one-dimensional coherent synchrotron radiation (CSR) model, while the other one starts from the first principle with a so-called 3D sub-bunch method. The simulations indicate that the CSR effect dominates the horizontal emittance growth and the 1D CSR model underestimates the final bunch duration and emittance because of the very large transverse-to-longitudinal aspect ratio of the sub-fs bunch. Particularly, the CSR effect is also strongly affected by the vertical bunch size. Due to the coupling between the horizontal and longitudinal phase spaces, the bunch duration at the entrance of the last dipole magnet of the chicane is still significantly longer than that at the exit of the chicane, which considerably mitigates the impact of space charge and CSR effects on the beam quality. Exploiting this effect, a bunch charge of up to 4.8 pC in a sub-fs bunch could be simulated. In addition, we analytically and numerically investigate the impact of different jitter sources on the bunch arrival-time jitter downstream of the chicane, and define the tolerance budgets assuming realistic values of the stability of the linac for different bunch charges and compression schemes.

a Novel Technique for Precision Geometric Correction of Jitter Distortion for the Europa Imaging System and Other Rolling-Shutter Cameras

NASA Astrophysics Data System (ADS)

Kirk, R. L.; Shepherd, M.; Sides, S. C.

2018-04-01

We use simulated images to demonstrate a novel technique for mitigating geometric distortions caused by platform motion ("jitter") as two-dimensional image sensors are exposed and read out line by line ("rolling shutter"). The results indicate that the Europa Imaging System (EIS) on NASA's Europa Clipper can likely meet its scientific goals requiring 0.1-pixel precision. We are therefore adapting the software used to demonstrate and test rolling shutter jitter correction to become part of the standard processing pipeline for EIS. The correction method will also apply to other rolling-shutter cameras, provided they have the operational flexibility to read out selected "check lines" at chosen times during the systematic readout of the frame area.

Detecting Motion from a Moving Platform; Phase 2: Lightweight, Low Power Robust Means of Removing Image Jitter

DTIC Science & Technology

2011-11-01

common housefly , Musca domestica. “Lightweight, Low Power Robust Means of Removing Image Jitter,” (AFRL-RX-TY-TR-2011-0096-02) develops an optimal...biological vision system of the common housefly , Musca domestica. Several variations of this sensor were designed, simulated extensively, and hardware

Full-custom design of split-set data weighted averaging with output register for jitter suppression

NASA Astrophysics Data System (ADS)

Jubay, M. C.; Gerasta, O. J.

2015-06-01

A full-custom design of an element selection algorithm, named as Split-set Data Weighted Averaging (SDWA) is implemented in 90nm CMOS Technology Synopsys Library. SDWA is applied in seven unit elements (3-bit) using a thermometer-coded input. Split-set DWA is an improved DWA algorithm which caters the requirement for randomization along with long-term equal element usage. Randomization and equal element-usage improve the spectral response of the unit elements due to higher Spurious-free dynamic range (SFDR) and without significantly degrading signal-to-noise ratio (SNR). Since a full-custom, the design is brought to transistor-level and the chip custom layout is also provided, having a total area of 0.3mm2, a power consumption of 0.566 mW, and simulated at 50MHz clock frequency. On this implementation, SDWA is successfully derived and improved by introducing a register at the output that suppresses the jitter introduced at the final stage due to switching loops and successive delays.

Community Environmental Response Facilitation Act (CERFA) Report, Sacramento Army Depot, Sacramento, California

DTIC Science & Technology

1994-04-01

Response, Compensation, and Liability Information System CERFA Community Environmental Response Facilitation Act CORTESE State-designated hazardous...waste cleanup sites DESCOM U.S. Army Depot Systems Command DTSC Department of Toxic Substance Control EMD Environmental Management Division EPA U.S...Environmental Protection Agency ERNS Emergency Response Notification system FFA Federal Facility Agreement FINDS Facility index system HWCSA Hazardous

Practical application of cross correlation technique to measure jitter of master-oscillator-power-amplifier laser system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Młyńczak, J.; Sawicz-Kryniger, K.; Fry, A. R.

2014-01-01

The Linac coherent light source (LCLS) at the SLAC National Accelerator Laboratory (SLAC) is the world’s first hard X-ray free electron laser (XFEL) and is capable of producing high-energy, femtosecond duration X-ray pulses. A common technique to study fast timescale physical phenomena, various “pump/probe” techniques are used. In these techniques there are two lasers, one optical and one X-ray, that work as a pump and as a probe to study dynamic processes in atoms and molecules. In order to resolve phenomena that occur on femtosecond timescales, it is imperative to have very precise timing between the optical lasers and X-raysmore » (on the order of ~ 20 fs or better). The lasers are synchronized to the same RF source that drives the accelerator and produces the X-ray laser. However, elements in the lasers cause some drift and time jitter, thereby de-synchronizing the system. This paper considers cross-correlation technique as a way to quantify the drift and jitter caused by the regenerative amplifier of the ultrafast optical laser.« less

Sexual Assertiveness Mediates the Associations Between Partner Facilitative Responses and Sexual Outcomes in Women With Provoked Vestibulodynia.

PubMed

McNicoll, Gabrielle; Corsini-Munt, Serena; O Rosen, Natalie; McDuff, Pierre; Bergeron, Sophie

2017-10-03

Provoked vestibulodynia (PVD) is a recurrent idiopathic vulvo-vaginal pain associated with negative sexual and psychological consequences. Facilitative partner responses to pain are currently receiving empirical attention because they are positively associated with women's sexual outcomes. However, the mechanisms through which facilitative responses to pain are associated with these outcomes have not been examined. One potential mechanism is sexual assertiveness, which has been found to be associated with better sexual function and satisfaction in women with PVD. The present study examined whether women's sexual assertiveness mediated the association between women's perception of facilitative partner responses and women's sexual function and satisfaction. Women (N = 140) with PVD symptomatology completed self-reported questionnaires evaluating their perception of their partners' facilitative responses, and their own sexual assertiveness, sexual function, and sexual satisfaction. Dependent measures were sexual function measured by the Female Sexual Function Index and sexual satisfaction assessed by the Global Measure of Sexual Satisfaction Scale. Results indicated that women's higher sexual assertiveness mediated the association between their greater perceived facilitative partner responses and their improved sexual function and satisfaction. Findings suggest a potential mechanism through which partner responses may be associated with women's sexual outcomes.

Toward Pride and Professionalism: Increasing Personal Responsibility. Facilitator Guide.

DTIC Science & Technology

1985-05-22

Stress Intervention. Richmond, CA: New Harbinger, 1981. 6. Medical Device Corporation, 1555 Bellefontaine, North Drive, Indianapolis, Indiana, 46202. (317...impair one’s cellular building and repair, as well as immune responses, making him or her less able to withstand bacterial and viral infection. Cancer ...facilitator should begin a collection of ads--perhaps those from medical magazines, treatment magazines, or other professional sources not ordinarily

The measurement of solute diffusion coefficients in dilute liquid alloys: the influence of unit gravity and g-jitter on buoyancy convection.

PubMed

Smith, R W; Yang, B J; Huang, W D

2004-11-01

Liquid diffusion experiments conducted on the MIR space station using the Canadian Space Agency QUELD II processing facility and the microgravity isolation mount (MIM) showed that g-jitter significantly increased the measured solute diffusion coefficients. In some experiments, milli-g forced vibration was superimposed on the sample when isolated from the ambient g-jitter; this resulted in markedly increased solute transport. To further explore the effects arising in these long capillary diffusion couples from the absence of unit-gravity and the presence of the forced g-jitter, the effects of a 1 milli-g forcing vibration on the mass transport in a 1.5 mm diameter long capillary diffusion couple have been simulated. In addition, to increase understanding of the role of unit gravity in determining the extent to which gravity can influence measured diffusion coefficient values, comparative experiments involving gold, silver, and antimony diffusing in liquid lead have been carried out using a similar QUELD II facility to that employed in the QUELD II/MIM/MIR campaign but under terrestrial conditions. It was found that buoyancy-driven convection may still persist in the liquid even when conditions are arranged for a continuously decreasing density gradient up the axis of a vertical long capillary diffusion couple due to the presence of small radial temperature gradients.

Design of a Sub-Picosecond Jitter with Adjustable-Range CMOS Delay-Locked Loop for High-Speed and Low-Power Applications

PubMed Central

Abdulrazzaq, Bilal I.; Ibrahim, Omar J.; Kawahito, Shoji; Sidek, Roslina M.; Shafie, Suhaidi; Yunus, Nurul Amziah Md.; Lee, Lini; Halin, Izhal Abdul

2016-01-01

A Delay-Locked Loop (DLL) with a modified charge pump circuit is proposed for generating high-resolution linear delay steps with sub-picosecond jitter performance and adjustable delay range. The small-signal model of the modified charge pump circuit is analyzed to bring forth the relationship between the DLL’s internal control voltage and output time delay. Circuit post-layout simulation shows that a 0.97 ps delay step within a 69 ps delay range with 0.26 ps Root-Mean Square (RMS) jitter performance is achievable using a standard 0.13 µm Complementary Metal-Oxide Semiconductor (CMOS) process. The post-layout simulation results show that the power consumption of the proposed DLL architecture’s circuit is 0.1 mW when the DLL is operated at 2 GHz. PMID:27690040

Few-femtosecond-resolution characterization and suppression of excess timing jitter and drift in indoor atmospheric frequency comb transfer.

PubMed

Kang, Jinho; Shin, Junho; Kim, Chur; Jung, Kwangyun; Park, Suhyeon; Kim, Jungwon

2014-10-20

We characterize the timing jitter spectral density of the time-of-flight (TOF) in the indoor atmospheric transfer of optical pulse train over 10 decades of Fourier frequency range (10 μHz - 100 kHz) with sub-100-as resolution using a balanced optical cross-correlator (BOC). Based on the well-known theory for atmospheric transfer of a laser beam, we could fit the measured timing jitter power spectral density to the theory and analyze it with a fairly good agreement from 20 mHz to 10 Hz Fourier frequency range. Moreover, we demonstrate that the BOC-based timing stabilization method can suppress the excess fluctuations in timing from >200 fs (rms) to 2.6 fs (rms) maintained over 130 hours when an optical pulse train is transferred over a 76.2-m long free-space beam path in laboratory environment. The demonstrated stabilization result corresponds to 4 × 10(-20) overlapping Allan deviation at 117,000 s averaging time.

Agile Blocker and Clock Jitter Tolerant Low-Power Frequency Selective Receiver with Energy Harvesting Capability.

PubMed

Hasan, Abul; Helaoui, Mohamed; Ghannouchi, Fadhel M

2017-08-29

In this article, a novel tunable, blocker and clock jitter tolerant, low power, quadrature phase shift frequency selective (QPS-FS) receiver with energy harvesting capability is proposed. The receiver's design embraces and integrates (i) the baseband to radio frequency (RF) impedance translation concept to improve selectivity over that of conventional homodyne receiver topologies and (ii) broadband quadrature phase shift circuitry in the RF path to remove an active multi-phase clock generation circuit in passive mixer (PM) receivers. The use of a single local oscillator clock signal with a passive clock division network improves the receiver's robustness against clock jitter and reduces the source clock frequency by a factor of N, compared to PM receivers using N switches (N≥4). As a consequence, the frequency coverage of the QPS-FS receiver is improved by a factor of N, given a clock source of maximum frequency; and, the power consumption of the whole receiver system can eventually be reduced. The tunable QPS-FS receiver separates the wanted RF band signal from the unwanted blockers/interferers. The desired RF signal is frequency down-converted to baseband, while the undesired blocker/interferer signals are reflected by the receiver, collected and could be energy recycled using an auxiliary energy harvesting device.

Effect of signal jitter on the spectrum of rotor impulsive noise

NASA Technical Reports Server (NTRS)

Brooks, Thomas F.

1987-01-01

The effect of randomness or jitter of the acoustic waveform on the spectrum of rotor impulsive noise is studied because of its importance for data interpretation. An acoustic waveform train is modelled representing rotor impulsive noise. The amplitude, shape, and period between occurrences of individual pulses are allowed to be randomized assuming normal probability distributions. Results, in terms of the standard deviations of the variable quantities, are given for the autospectrum as well as special processed spectra designed to separate harmonic and broadband rotor noise components. Consideration is given to the effect of accuracy in triggering or keying to a rotor one per revolution signal. An example is given showing the resultant spectral smearing at the high frequencies due to the pulse signal period variability.

Effect of signal jitter on the spectrum of rotor impulsive noise

NASA Technical Reports Server (NTRS)

Brooks, Thomas F.

1988-01-01

The effect of randomness or jitter of the acoustic waveform on the spectrum of rotor impulsive noise is studied because of its importance for data interpretation. An acoustic waveform train is modeled representing rotor impulsive noise. The amplitude, shape, and period between occurrences of individual pulses are allowed to be randomized assuming normal probability distributions. Results, in terms of the standard deviations of the variable quantities, are given for the autospectrum as well as special processed spectra designed to separate harmonic and broadband rotor noise components. Consideration is given to the effect of accuracy in triggering or keying to a rotor one per revolution signal. An example is given showing the resultant spectral smearing at the high frequencies due to the pulse signal period variability.

Dynamic/Jitter Assessment of Multiple Potential HabEx Structural Designs

NASA Technical Reports Server (NTRS)

Knight, J. Brent; Stahl, H. Philip; Singleton, Andy; Hunt, Ron; Therrell, Melissa; Caldwell, Kate; Garcia, Jay; Baysinger, Mike

2017-01-01

One of the driving structural requirements of the Habitable Exo-Planet (HabEx) telescope is to maintain Line Of Sight (LOS) stability between the Primary Mirror (PM) and Secondary Mirror (SM) of = 5 mas. Dynamic analyses of two configurations of a proposed (HabEx) 4 meter off-axis telescope structure were performed to predict effects of jitter on primary/secondary mirror alignment. The dynamic disturbance used as the forcing function was the James Webb Space Telescope reaction wheel assembly vibration emission specification level. The objective of these analyses was to predict "order-of-magnitude" performance for various structural configurations which will roll into efforts to define the HabEx structural design's global architecture. Two variations of the basic architectural design were analyzed. Relative motion between the PM and the SM for each design configuration are reported.

Is Empathic Accuracy Enough to Facilitate Responsive Behavior in Dyadic Interaction? Distinguishing Ability From Motivation.

PubMed

Winczewski, Lauren A; Bowen, Jeffrey D; Collins, Nancy L

2016-03-01

Growing evidence suggests that interpersonal responsiveness-feeling understood, validated, and cared for by other people-plays a key role in shaping the quality of one's social interactions and relationships. But what enables people to be interpersonally responsive to others? In the current study, we argued that responsiveness requires not only accurate understanding but also compassionate motivation. Specifically, we hypothesized that understanding another person's thoughts and feelings (empathic accuracy) would foster responsive behavior only when paired with benevolent motivation (empathic concern). To test this idea, we asked couples (N = 91) to discuss a personal or relationship stressor; we then assessed empathic accuracy, empathic concern, and responsive behavior. As predicted, when listeners' empathic concern was high, empathic accuracy facilitated responsiveness; but when empathic concern was low, empathic accuracy was unhelpful (and possibly harmful) for responsiveness. These findings provide the first evidence that cognitive and affective forms of empathy work together to facilitate responsive behavior. © The Author(s) 2016.

Delegation of Authority Under the Community Environmental Response Facilitation Act (CERFA) - Decision Memorandum

EPA Pesticide Factsheets

This memorandum concerns how the Office of Enforcement (OE) proposed that two new authorities under the Community Environmental Response Facilitation Act (CERFA) be delegated to the Regional Administrators.

GNSS software receiver sampling noise and clock jitter performance and impact analysis

NASA Astrophysics Data System (ADS)

Chen, Jian Yun; Feng, XuZhe; Li, XianBin; Wu, GuangYao

2015-02-01

In the design of a multi-frequency multi-constellation GNSS software defined radio receivers is becoming more and more popular due to its simple architecture, flexible configuration and good coherence in multi-frequency signal processing. It plays an important role in navigation signal processing and signal quality monitoring. In particular, GNSS software defined radio receivers driving the sampling clock of analogue-to-digital converter (ADC) by FPGA implies that a more flexible radio transceiver design is possible. According to the concept of software defined radio (SDR), the ideal is to digitize as close to the antenna as possible. Whereas the carrier frequency of GNSS signal is of the frequency of GHz, converting at this frequency is expensive and consumes more power. Band sampling method is a cheaper, more effective alternative. When using band sampling method, it is possible to sample a RF signal at twice the bandwidth of the signal. Unfortunately, as the other side of the coin, the introduction of SDR concept and band sampling method induce negative influence on the performance of the GNSS receivers. ADC's suffer larger sampling clock jitter generated by FPGA; and low sampling frequency introduces more noise to the receiver. Then the influence of sampling noise cannot be neglected. The paper analyzes the sampling noise, presents its influence on the carrier noise ratio, and derives the ranging error by calculating the synchronization error of the delay locked loop. Simulations aiming at each impact factors of sampling-noise-induced ranging error are performed. Simulation and experiment results show that if the target ranging accuracy is at the level of centimeter, the quantization length should be no less than 8 and the sampling clock jitter should not exceed 30ps.

Explaining the morphology of supernova remnant (SNR) 1987A with the jittering jets explosion mechanism

NASA Astrophysics Data System (ADS)

Bear, Ealeal; Soker, Noam

2018-07-01

We find that the remnant of supernova (SN) 1987A shares some morphological features with four supernova remnants (SNRs) that have signatures of shaping by jets, and from that we strengthen the claim that jets played a crucial role in the explosion of SN 1987A. Some of the morphological features appear also in planetary nebulae (PNe) where jets are observed. The clumpy ejecta brings us to support the claim that the jittering jets explosion mechanism can account for the structure of the remnant of SN 1987A, i.e. SNR 1987A. We conduct a preliminary attempt to quantify the fluctuations in the angular momentum of the mass that is accreted on to the newly born neutron star via an accretion disc or belt. The accretion disc/belt launches jets that explode core collapse supernovae (CCSNe). The relaxation time of the accretion disc/belt is comparable to the duration of a typicalfigu jet-launching episode in the jittering jets explosion mechanism, and hence the disc/belt has no time to relax. We suggest that this might explain the two unequal opposite jets that later lead to the unequal sides of the elongated structures in some SNRs of CCSNe. We reiterate our earlier call for a paradigm shift from a neutrino-driven explosion to a jet-driven explosion of CCSNe.

Explaining the morphology of supernova remnant (SNR) 1987A with the jittering jets explosion mechanism

NASA Astrophysics Data System (ADS)

Bear, Ealeal; Soker, Noam

2018-04-01

We find that the remnant of supernova (SN) 1987A shares some morphological features with four supernova remnants (SNRs) that have signatures of shaping by jets, and from that we strengthen the claim that jets played a crucial role in the explosion of SN 1987A. Some of the morphological features appear also in planetary nebulae (PNe) where jets are observed. The clumpy ejecta bring us to support the claim that the jittering jets explosion mechanism can account for the structure of the remnant of SN 1987A, i.e., SNR 1987A. We conduct a preliminary attempt to quantify the fluctuations in the angular momentum of the mass that is accreted on to the newly born neutron star via an accretion disk or belt. The accretion disk/belt launches the jets that explode core collapse supernovae (CCSNe). The relaxation time of the accretion disk/belt is comparable to the duration of a typical jet-launching episode in the jittering jets explosion mechanism, and hence the disk/belt has no time to relax. We suggest that this might explain two unequal opposite jets that later lead to unequal sides of the elongated structures in some SNRs of CCSNe. We reiterate our earlier call for a paradigm shift from neutrino-driven explosion to a jet-driven explosion of CCSNe.

Simulation of sloshing dynamics induced forces and torques actuated on dewar container driven by gravity gradient and jitter accelerations in microgravity

NASA Technical Reports Server (NTRS)

Hung, R. J.; Pan, H. L.

1993-01-01

Some experimental spacecraft use superconducting sensors for gyro read-out and so must be maintained at a very low temperature. The boil-off from the cryogenic liquid used to cool the sensors can also be used, as the Gravity Probe B (GP-B) spacecraft does, as propellant to maintain attitude control and drag-free operation of the spacecraft. The cryogenic liquid for such spacecraft is, however, susceptible to both slosh-like motion and non-axisymmetric configurations under the influence of various kinds of gravity jitter and gravity gradient accelerations. Hence, it is important to quantify the magnitude of the liquid-induced perturbations on the spacecraft. We use the example of the GP-B to investigate such perturbations by numerical simulations. For this spacecraft disturbances can be imposed on the liquid by atmospheric drag, spacecraft attitude control maneuvers, and the earth's gravity gradient. More generally, onboard machinery vibrations and crew motion can also create disturbances. Recent studies suggest that high frequency disturbances are relatively unimportant in causing liquid motions in comparison to low frequency ones. The results presented here confirm this conclusion. After an initial calibration period, the GP-B spacecraft rotates in orbit at 0.1 rpm about the tank symmetry axis. For this rotation rate, the equilibrium liquid free surface shape is a 'doughnut' configuration for all residual gravity levels of 10(exp -6) g(sub 0) or less, as shown by experiments and by numerical simulations; furthermore, the superfluid behavior of the 1.8 K liquid helium used in GP-B eliminates temperature gradients and therefore such effects as Marangoni convection do not have to be considered. Classical fluid dynamics theory is used as the basis of the numerical simulations here, since Mason's experiments show that the theory is applicable for cryogenic liquid helium in large containers. To study liquid responses to various disturbances, we investigate and simulate

Electro-Optic Time-to-Space Converter for Optical Detector Jitter Mitigation

NASA Technical Reports Server (NTRS)

Birnbaum, Kevin; Farr, William

2013-01-01

A common problem in optical detection is determining the arrival time of a weak optical pulse that may comprise only one to a few photons. Currently, this problem is solved by using a photodetector to convert the optical signal to an electronic signal. The timing of the electrical signal is used to infer the timing of the optical pulse, but error is introduced by random delay between the absorption of the optical pulse and the creation of the electrical one. To eliminate this error, a time-to-space converter separates a sequence of optical pulses and sends them to different photodetectors, depending on their arrival time. The random delay, called jitter, is at least 20 picoseconds for the best detectors capable of detecting the weakest optical pulses, a single photon, and can be as great as 500 picoseconds. This limits the resolution with which the timing of the optical pulse can be measured. The time-to-space converter overcomes this limitation. Generally, the time-to-space converter imparts a time-dependent momentum shift to the incoming optical pulses, followed by an optical system that separates photons of different momenta. As an example, an electro-optic phase modulator can be used to apply longitudinal momentum changes (frequency changes) that vary in time, followed by an optical spectrometer (such as a diffraction grating), which separates photons with different momenta into different paths and directs them to impinge upon an array of photodetectors. The pulse arrival time is then inferred by measuring which photodetector receives the pulse. The use of a time-to-space converter mitigates detector jitter and improves the resolution with which the timing of an optical pulse is determined. Also, the application of the converter enables the demodulation of a pulse position modulated signal (PPM) at higher bandwidths than using previous photodetector technology. This allows the creation of a receiver for a communication system with high bandwidth and high bits

Measurement of an image jitter of an extended incoherent radiation source

NASA Astrophysics Data System (ADS)

Lukin, V. P.; Nosov, V. V.

2017-06-01

A scheme of an image jitter measuring device, which uses an extended incoherent source as a radiation source, is presented. The efficiency of the measuring device is analysed analytically and numerically in order to justify the operation of the adaptive optical system that does not require special creation or formation of a reference source. The features of the formed image of incoherent radiation are considered, in particular from the point of view of its possible application for measuring the phase fluctuations of optical waves propagating in a turbulent atmosphere (the adaptive system monitors the image of a self-luminous object illuminated by extraneous sources). The possibility of utilising a Shack-Hartmann wavefront sensor in adaptive systems using the image of an arbitrary object (or its fragment) as a reference source is shown.

Nuclear translocation of Skp2 facilitates its destruction in response to TGFβ signaling

PubMed Central

Wu, George

2011-01-01

Skp2, a F-box protein that determines the substrate specificity for SCF ubiquitin ligase, has recently been demonstrated to be degraded by Cdh1/APC in response to TGFβ signaling. The TGFβ-induced Skp2 proteolysis results in the stabilization of p27 that is necessary to facilitate TGFβ cytostatic effect. Previous observation from immunocytochemistry indicates that Cdh1 principally localizes in the nucleus while Skp2 mainly localizes in the cytosol, which leaves us a puzzle on how Skp2 is recognized and then ubiquitylated by Cdh1/APC in response to TGFβ stimulation. Here, we report that Skp2 is rapidly translocated from the cytosol to the nucleus upon the cellular stimulation with TGFβ. Using a combinatorial approach of immunocytochemistry, biochemical-fraction-coupled immunoprecipitation, mutagenesis as well as protein degradation assay, we have demonstrated that the TGFβ-induced Skp2 nucleus translocation is critical for TGFβ cytostatic effect that allows physical interaction between Cdh1 and Skp2 and in turn facilitates the Skp2 ubquitylation by Cdh1/APC. Disruption of nuclear localization motifs on Skp2 stabilizes Skp2 in the presence of TGFβ signaling, which attenuates TGFβ-induced p27 accumulation and antagonizes TGFβ-induced growth inhibition. Our finding reveals a cellular mechanism that facilitates Skp2 ubiquitylation by Cdh1/APC in response to TGFβ. PMID:21212736

Sloshing of Cryogenic Helium Driven by Lateral Impulse/Gravity Gradient-Dominated/or g-Jitter-Dominated Accelerations and Orbital Dynamics

NASA Technical Reports Server (NTRS)

Hung, R. J.; Long, Y. T.; Zu, G. J.

1996-01-01

The coupling of slosh dynamics within a partially filled rotating dewar of superfluid helium 11 with spacecraft orbital dynamics is investigated in response to the environmental disturbances of (a) lateral impulses, (b) gravity gradients and (c) g-jitter forces. The purpose of this study is to investigate how the coupling of helium 11 fluid slosh dynamics driven by three cases of environmental force with spacecraft dynamics can affect the bubble deformations and their associated fluid and spacecraft mass centre fluctuations. The numerical computation of slosh dynamics is based on a rotational frame, while the spacecraft dynamics is associated with a non-rotational frame. Results show that the major contribution of orbital dynamics is driven by coupling with slosh dynamics. Neglecting the effect of slosh dynamics acting on the spacecraft may lead to the wrong results for the development of orbital and attitude control techniques.

Picosecond 1064-nm fiber laser with tunable pulse width and low timing jitter

NASA Astrophysics Data System (ADS)

Tian, Wenyan; Zhang, Shukui

2018-02-01

We report an all-fiber, linearly polarized, 1.1-W, 1064-nm fiber laser based on a two-stage Ytterbium-doped fiber amplifier seeded by a gain-switched diode laser with tunable pulse width from 21 to 200 ps at repetition rates of 0.5-1.5 GHz. Timing jitter of our 1064-nm fiber laser was measured to be 0.60 ps over 10 Hz-40 MHz when the gain-switched diode laser was operated at a repetition rate of 0.5, 1, and 1.5 GHz. The fiber laser offers an excellent long term power stability of +/- 0.3% and wavelength stability of +/- 0.01 nm over 8 hours

A Building-Resolved Wind Field Library for Vancouver: Facilitating CBRN Emergency Response for the 2010 Winter Olympic Games

DTIC Science & Technology

2010-06-01

Vancouver. Facilitating CBRN Emergency Response for the 2010 Winter Olympic Games E. Vee Defence R&D Canada- Suffield F.-S. Lien University of...ana a A Building-Resolved Wind Field Library for Vancouver. Facilitating CBRN Emergency Response for the 2010 Winter Olympic Games E. Yee Defence...support of emergency response applications (requiring quick turn- around times) for the 2010 Winter Olympic Games . To this purpose, mean wind and

Carrier-envelope phase stabilization with sub-10 as residual timing jitter.

PubMed

Borchers, B; Koke, S; Husakou, A; Herrmann, J; Steinmeyer, G

2011-11-01

We demonstrate carrier-envelope phase (CEP) stabilization of a mode-locked Ti:sapphire oscillator with unprecedented timing jitter of eight attoseconds. The stabilization performance is obtained by a combination of two different stabilization approaches. In a first step the drift of the CEP is stabilized with a conventional feedback loop by means of controlling the oscillator pump power with an acousto-optic modulator (AOM). In a second step we utilize a recently developed feed-forward type stabilization scheme which has a much higher control bandwith. Here an acousto-optic frequency shifter (AOFS) produces the stabilized output in the first diffraction order. Moreover, we present numerical results on the optimization of the length of the photonic crystal fiber, which is used to generate an octave-spanning spectrum, in order to optimize the sensitivity in the f-to-2f interferometers.

Instantaneous speed jitter detection via encoder signal and its application for the diagnosis of planetary gearbox

NASA Astrophysics Data System (ADS)

Zhao, Ming; Jia, Xiaodong; Lin, Jing; Lei, Yaguo; Lee, Jay

2018-01-01

In modern rotating machinery, rotary encoders have been widely used for the purpose of positioning and dynamic control. The study in this paper indicates that, the encoder signal, after proper processing, can be also effectively used for the health monitoring of rotating machines. In this work, a Kurtosis-guided local polynomial differentiator (KLPD) is proposed to estimate the instantaneous angular speed (IAS) of rotating machines based on the encoder signal. Compared with the central difference method, the KLPD is more robust to noise and it is able to precisely capture the weak speed jitters introduced by mechanical defects. The fault diagnosis of planetary gearbox has proven to be a challenging issue in both industry and academia. Based on the proposed KLPD, a systematic method for the fault diagnosis of planetary gearbox is proposed. In this method, residual time synchronous time averaging (RTSA) is first employed to remove the operation-related IAS components that come from normal gear meshing and non-stationary load variations, KLPD is then utilized to detect and enhance the speed jitter from the IAS residual in a data-driven manner. The effectiveness of proposed method has been validated by both simulated data and experimental data. The results demonstrate that the proposed KLPD-RTSA could not only detect fault signatures but also identify defective components, thus providing a promising tool for the health monitoring of planetary gearbox.

Techniques: Coach, Consultant, Critic, Counselor: The Multiple Roles of the Responsive Facilitator.

ERIC Educational Resources Information Center

Keenan, Thomas P.; Braxton-Brown, Greg

1991-01-01

Responsive facilitation is an interactive orientation to formal learning that requires an individual to assume a variety of roles and to be comfortable with diverse methodologies. The major roles assumed are coach, consultant, critic, and counselor. As illustrated by the redesign of an introductory computer science course, these practices can be…

A meta-analysis of plant facilitation in coastal dune systems: responses, regions, and research gaps.

PubMed

Castanho, Camila de Toledo; Lortie, Christopher J; Zaitchik, Benjamin; Prado, Paulo Inácio

2015-01-01

Empirical studies in salt marshes, arid, and alpine systems support the hypothesis that facilitation between plants is an important ecological process in severe or 'stressful' environments. Coastal dunes are both abiotically stressful and frequently disturbed systems. Facilitation has been documented, but the evidence to date has not been synthesized. We did a systematic review with meta-analysis to highlight general research gaps in the study of plant interactions in coastal dunes and examine if regional and local factors influence the magnitude of facilitation in these systems. The 32 studies included in the systematic review were done in coastal dunes located in 13 countries around the world but the majority was in the temperate zone (63%). Most of the studies adopt only an observational approach to make inferences about facilitative interactions, whereas only 28% of the studies used both observational and experimental approaches. Among the factors we tested, only geographic region mediates the occurrence of facilitation more broadly in coastal dune systems. The presence of a neighbor positively influenced growth and survival in the tropics, whereas in temperate and subartic regions the effect was neutral for both response variables. We found no evidence that climatic and local factors, such as life-form and life stage of interacting plants, affect the magnitude of facilitation in coastal dunes. Overall, conclusions about plant facilitation in coastal dunes depend on the response variable measured and, more broadly, on the geographic region examined. However, the high variability and the limited number of studies, especially in tropical region, indicate we need to be cautious in the generalization of the conclusions. Anyway, coastal dunes provide an important means to explore topical issues in facilitation research including context dependency, local versus regional drivers of community structure, and the importance of gradients in shaping the outcome of net

HAT-P-32b AND HAT-P-33b: TWO HIGHLY INFLATED HOT JUPITERS TRANSITING HIGH-JITTER STARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartman, J. D.; Bakos, G. A.; Torres, G.

2011-11-20

We report the discovery of two exoplanets transiting high-jitter stars. HAT-P-32b orbits the bright V = 11.289 late-F-early-G dwarf star GSC 3281-00800, with a period P = 2.150008 {+-} 0.000001 d. The stellar and planetary masses and radii depend on the eccentricity of the system, which is poorly constrained due to the high-velocity jitter ({approx}80 m s{sup -1}). Assuming a circular orbit, the star has a mass of 1.16 {+-} 0.04 M{sub Sun} and radius of 1.22 {+-} 0.02 R{sub Sun }, while the planet has a mass of 0.860 {+-} 0.164 M{sub J} and a radius of 1.789 {+-}more » 0.025 R{sub J}. The second planet, HAT-P-33b, orbits the bright V = 11.188 late-F dwarf star GSC 2461-00988, with a period P = 3.474474 {+-} 0.000001 d. As for HAT-P-32, the stellar and planetary masses and radii of HAT-P-33 depend on the eccentricity, which is poorly constrained due to the high jitter ({approx}50 m s{sup -1}). In this case, spectral line bisector spans (BSs) are significantly anti-correlated with the radial velocity residuals, and we are able to use this correlation to reduce the residual rms to {approx}35 m s{sup -1}. We find that the star has a mass of 1.38 {+-} 0.04 M{sub Sun} and a radius of 1.64 {+-} 0.03 R{sub Sun} while the planet has a mass of 0.762 {+-} 0.101 M{sub J} and a radius of 1.686 {+-} 0.045 R{sub J} for an assumed circular orbit. Due to the large BS variations exhibited by both stars we rely on detailed modeling of the photometric light curves to rule out blend scenarios. Both planets are among the largest radii transiting planets discovered to date.« less

Evaluative priming of naming and semantic categorization responses revisited: a mutual facilitation explanation.

PubMed

Schmitz, Melanie; Wentura, Dirk

2012-07-01

The evaluative priming effect (i.e., faster target responses following evaluatively congruent compared with evaluatively incongruent primes) in nonevaluative priming tasks (such as naming or semantic categorization tasks) is considered important for the question of how evaluative connotations are represented in memory. However, the empirical evidence is rather ambiguous: Positive effects as well as null results and negatively signed effects have been found. We tested the assumption that different processes are responsible for these results. In particular, we argue that positive effects are due to target-encoding facilitation (caused by a congruent prime), while negative effects are due to prime-activation maintenance (caused by a congruent target) and subsequent response conflict. In 4 experiments, we used a negative prime-target stimulus-onset asynchrony (SOA) to minimize target-encoding facilitation and maximize prime maintenance. In a naming task (Experiment 1), we found a negatively signed evaluative priming effect if prime and target competed for naming responses. In a semantic categorization task (i.e., person vs. animal; Experiments 2 and 3), response conflicts between prime and target were significantly larger in case of evaluative congruence compared with incongruence. These results corroborate the theory that a prime has more potential to interfere with the target response if its activation is maintained by an evaluatively congruent target. Experiment 4a/b indicated valence specificity of the effect. Implications for the memory representation of valence are discussed. 2012 APA, all rights reserved

Use of a Passive Reaction Wheel Jitter Isolation System to Meet the Advanced X-Ray Astrophysics Facility Imaging Performance Requirements

NASA Technical Reports Server (NTRS)

Pendergast, Karl J.; Schauwecker, Christopher J.

1998-01-01

Third in the series of NASA great observatories, the Advanced X-Ray Astrophysics Facility (AXAF) is scheduled for launch from the Space Shuttle in November of 1998. Following in the path of the Hubble Space Telescope and the Compton Gamma Ray Observatory, this observatory will image light at X-ray wavelengths, facilitating the detailed study of such phenomena as supernovae and quasars. The AXAF project is sponsored by the Marshall Space Flight Center in Huntsville, Alabama. Because of exacting requirements on the performance of the AXAF optical system, it was necessary to reduce the transmission of reaction wheel jitter disturbances to the observatory. This reduction was accomplished via use of a passive mechanical isolation system to interface the reaction wheels with the spacecraft central structure. In addition to presenting a description of the spacecraft, the isolation system, and the key image quality requirement flowdown, this paper details the analyses performed in support of system-level imaging performance requirement verification. These analyses include the identification of system-level requirement suballocations, quantification of imaging and pointing performance, and formulation of unit-level isolation system transmissibility requirements. Given in comparison to the non-isolated system imaging performance, the results of these analyses clearly illustrate the effectiveness of an innovative reaction wheel passive isolation system.

Exploratory behaviour and stressor hyper-responsiveness facilitate range expansion of an introduced songbird

PubMed Central

Liebl, Andrea L.; Martin, Lynn B.

2012-01-01

Global anthropogenic changes are occurring at an unprecedented rate; one change, human-facilitated introduction of species outside their native range, has had significant ecological and economic impacts. Surprisingly, what traits facilitate range expansions post-introduction is relatively unknown. This information could help predict future expansions of introduced species as well as native species shifting their ranges as climate conditions change. Here, we asked whether specific behavioural and physiological traits were important in the ongoing expansion of house sparrows (Passer domesticus) across Kenya. We predicted that birds at the site of initial introduction (Mombasa, introduced approx. 1950) would behave and regulate corticosterone, a stress hormone, differently than birds at the range edge (Kakamega, approx. 885 km from Mombasa; colonized within the last 5 years). Specifically, we predicted greater exploratory behaviour and stronger corticosterone response to stressors in birds at the range edge, which may facilitate the identification, resolution and memory of stressors. Indeed, we found that distance from Mombasa (a proxy for population age) was a strong predictor of both exploratory behaviour and corticosterone release in response to restraint (but only while birds were breeding). These results suggest that certain behavioural and neuroendocrine traits may influence the ability of species to colonize novel habitats. PMID:22951742

Chronic Inhibition of Dopamine β-Hydroxylase Facilitates Behavioral Responses to Cocaine in Mice

PubMed Central

Gaval-Cruz, Meriem; Liles, Larry Cameron; Iuvone, Paul Michael; Weinshenker, David

2012-01-01

The anti-alcoholism medication, disulfiram (Antabuse), decreases cocaine use in humans regardless of concurrent alcohol consumption and facilitates cocaine sensitization in rats, but the functional targets are unknown. Disulfiram inhibits dopamine β-hydroxylase (DBH), the enzyme that converts dopamine (DA) to norepinephrine (NE) in noradrenergic neurons. The goal of this study was to test the effects of chronic genetic or pharmacological DBH inhibition on behavioral responses to cocaine using DBH knockout (Dbh −/−) mice, disulfiram, and the selective DBH inhibitor, nepicastat. Locomotor activity was measured in control (Dbh +/−) and Dbh −/− mice during a 5 day regimen of saline+saline, disulfiram+saline, nepicastat+saline, saline+cocaine, disulfiram+cocaine, or nepicastat+cocaine. After a 10 day withdrawal period, all groups were administered cocaine, and locomotor activity and stereotypy were measured. Drug-naïve Dbh −/− mice were hypersensitive to cocaine-induced locomotion and resembled cocaine-sensitized Dbh +/− mice. Chronic disulfiram administration facilitated cocaine-induced locomotion in some mice and induced stereotypy in others during the development of sensitization, while cocaine-induced stereotypy was evident in all nepicastat-treated mice. Cocaine-induced stereotypy was profoundly increased in the disulfiram+cocaine, nepicastat+cocaine, and nepicastat+saline groups upon cocaine challenge after withdrawal in Dbh +/− mice. Disulfiram or nepicastat treatment had no effect on behavioral responses to cocaine in Dbh −/− mice. These results demonstrate that chronic DBH inhibition facilitates behavioral responses to cocaine, although different methods of inhibition (genetic vs. non-selective inhibitor vs. selective inhibitor) enhance qualitatively different cocaine-induced behaviors. PMID:23209785

Improving carrier-envelope phase stability in optical parametric chirped-pulse amplifiers by control of timing jitter.

PubMed

Hädrich, S; Rothhardt, J; Krebs, M; Demmler, S; Limpert, J; Tünnermann, A

2012-12-01

It is shown that timing jitter in optical parametric chirped-pulse amplification induces spectral drifts that transfer to carrier-envelope phase (CEP) instabilities via dispersion. Reduction of this effect requires temporal synchronization, which is realized with feedback obtained from the angularly dispersed idler. Furthermore, a novel method to measure the CEP drifts by utilizing parasitic second harmonic generation within parametric amplifiers is presented. Stabilization of the timing allows the obtainment of a CEP stability of 86 mrad over 40 min at 150 kHz repetition rate.

Superfluid helium sloshing dynamics induced oscillations and fluctuations of angular momentum, force and moment actuated on spacecraft driven by gravity gradient or jitter acceleration associated with slew motion

NASA Technical Reports Server (NTRS)

Hung, R. J.

1994-01-01

The generalized mathematical formulation of sloshing dynamics for partially filled liquid of cryogenic superfluid helium II in dewar containers driven by the gravity gradient and jitter accelerations associated with slew motion for the purpose to perform scientific observation during the normal spacecraft operation are investigated. An example is given with the Advanced X-Ray Astrophysics Facility-Spectroscopy (AXAF-S) for slew motion which is responsible for the sloshing dynamics. The jitter accelerations include slew motion, spinning motion, atmospheric drag on the spacecraft, spacecraft attitude motions arising from machinery vibrations, thruster firing, pointing control of spacecraft, crew motion, etc. Explicit mathematical expressions to cover these forces acting on the spacecraft fluid systems are derived. The numerical computation of sloshing dynamics is based on the non-inertia frame spacecraft bound coordinate, and solve time-dependent, three-dimensional formulations of partial differential equations subject to initial and boundary conditions. The explicit mathematical expressions of boundary conditions to cover capillary force effect on the liquid-vapor interface in microgravity environments are also derived. The formulations of fluid moment and angular moment fluctuations in fluid profiles induced by the sloshing dynamics, together with fluid stress and moment fluctuations exerted on the spacecraft dewar containers have also been derived. Examples are also given for cases applicable to the AXAF-S spacecraft sloshing dynamics associated with slew motion.

High doses of salicylate causes prepulse facilitation of onset-gap induced acoustic startle response.

PubMed

Sun, Wei; Doolittle, Lauren; Flowers, Elizabeth; Zhang, Chao; Wang, Qiuju

2014-01-01

Prepulse inhibition of acoustic startle reflex (PPI), a well-established method for evaluating sensorimotor gating function, has been used to detect tinnitus in animal models. Reduced gap induced PPI (gap-PPI) was considered as a sign of tinnitus. The silent gap used in the test contains both onset and offset signals. Tinnitus may affect these cues differently. In this experiment, we studied the effects of a high dose of salicylate (250 mg/kg, i.p.), an inducer of reversible tinnitus and sensorineural hearing loss, on gap-PPI induced by three different gaps: an onset-gap with 0.1 ms onset and 25 ms offset time, an offset-gap with 25 ms onset and 0.1 ms offset time, and an onset-offset-gap with 0.1 ms onset and offset time. We found that the onset-gaps induced smaller inhibitions than the offset-gaps before salicylate treatment. The offset-gap induced PPI was significantly reduced 1-3h after salicylate treatment. However, the onset-gap caused a facilitation of startle response. These results suggest that salicylate induced reduction of gap-PPI was not only caused by the decrease of offset-gap induced PPI, but also by the facilitation induced by the onset-gap. Since the onset-gap induced PPI is caused by neural offset response, our results suggest that salicylate may cause a facilitation of neural response to an offset acoustical signal. Treatment of vigabatrin (60 mg/kg/day, 14 days), which elevates the GABA level in the brain, blocked the offset-gap induced PPI and onset-gap induced facilitation caused by salicylate. These results suggest that enhancing GABAergic activities can alleviate salicylate induced tinnitus. Published by Elsevier B.V.

The identification of credit card encoders by hierarchical cluster analysis of the jitters of magnetic stripes.

PubMed

Leung, S C; Fung, W K; Wong, K H

1999-01-01

The relative bit density variation graphs of 207 specimen credit cards processed by 12 encoding machines were examined first visually, and then classified by means of hierarchical cluster analysis. Twenty-nine credit cards being treated as 'questioned' samples were tested by way of cluster analysis against 'controls' derived from known encoders. It was found that hierarchical cluster analysis provided a high accuracy of identification with all 29 'questioned' samples classified correctly. On the other hand, although visual comparison of jitter graphs was less discriminating, it was nevertheless capable of giving a reasonably accurate result.

Detecting vocal fatigue in student singers using acoustic measures of mean fundamental frequency, jitter, shimmer, and harmonics-to-noise ratio

NASA Astrophysics Data System (ADS)

Sisakun, Siphan

2000-12-01

The purpose of this study is to explore the ability of four acoustic parameters, mean fundamental frequency, jitter, shimmer, and harmonics-to-noise ratio, to detect vocal fatigue in student singers. The participants are 15 voice students, who perform two distinct tasks, data collection task and vocal fatiguing task. The data collection task includes the sustained vowel /a/, reading a standard passage, and self-rate on a vocal fatigue form. The vocal fatiguing task is the vocal practice of musical scores for a total of 45 minutes. The four acoustic parameters are extracted using the software EZVoicePlus. The data analyses are performed to answer eight research questions. The first four questions relate to correlations of the self-rating scale and each of the four parameters. The next four research questions relate to differences in the parameters over time using one-factor repeated measures analysis of variance (ANOVA). The result yields a proposed acoustic profile of vocal fatigue in student singers. This profile is characterized by increased fundamental frequency; slightly decreased jitter; slightly decreased shimmer; and slightly increased harmonics-to-noise ratio. The proposed profile requires further investigation.

Species-specific defence responses facilitate conspecifics and inhibit heterospecifics in above–belowground herbivore interactions

PubMed Central

Huang, Wei; Siemann, Evan; Xiao, Li; Yang, Xuefang; Ding, Jianqing

2014-01-01

Conspecific and heterospecific aboveground and belowground herbivores often occur together in nature and their interactions may determine community structure. Here we show how aboveground adults and belowground larvae of the tallow tree specialist beetle Bikasha collaris and multiple heterospecific aboveground species interact to determine herbivore performance. Conspecific aboveground adults facilitate belowground larvae, but other aboveground damage inhibits larvae or has no effect. Belowground larvae increase conspecific adult feeding, but decrease heterospecific aboveground insect feeding and abundance. Chemical analyses and experiments with plant populations varying in phenolics show that all these positive and negative effects on insects are closely related to root and shoot tannin concentrations. Our results show that specific plant herbivore responses allow herbivore facilitation and inhibition to co-occur, likely shaping diverse aboveground and belowground communities. Considering species-specific responses of plants is critical for teasing apart inter- and intraspecific interactions in aboveground and belowground compartments. PMID:25241651

Asymmetric dual-loop feedback to suppress spurious tones and reduce timing jitter in self-mode-locked quantum-dash lasers emitting at 155 μm

NASA Astrophysics Data System (ADS)

Asghar, Haroon; McInerney, John G.

2017-09-01

We demonstrate an asymmetric dual-loop feedback scheme to suppress external cavity side-modes induced in self-mode-locked quantum-dash lasers with conventional single and dual-loop feedback. In this letter, we achieved optimal suppression of spurious tones by optimizing the length of second delay time. We observed that asymmetric dual-loop feedback, with large (~8x) disparity in cavity lengths, eliminates all external-cavity side-modes and produces flat RF spectra close to the main peak with low timing jitter compared to single-loop feedback. Significant reduction in RF linewidth and reduced timing jitter was also observed as a function of increased second feedback delay time. The experimental results based on this feedback configuration validate predictions of recently published numerical simulations. This interesting asymmetric dual-loop feedback scheme provides simplest, efficient and cost effective stabilization of side-band free optoelectronic oscillators based on mode-locked lasers.

Non-Critical-Care Nurses' Perceptions of Facilitators and Barriers to Rapid Response Team Activation.

PubMed

Jenkins, Sheryl Henry; Astroth, Kim Schafer; Woith, Wendy Mann

2015-01-01

Rapid response teams can save lives but are only effective when activated. We surveyed 50 nurses for their perceptions of facilitators and barriers to activation. Findings showed that participants need more education on their role and when to activate the rapid response team. Nurses who comprise the team need help building their communication skills. We recommend nursing professional development specialists increase the frequency of offerings and expand the focus on roles, activation criteria, and communication skills.

Harmful or helpful: perceived solicitous and facilitative partner responses are differentially associated with pain and sexual satisfaction in women with provoked vestibulodynia.

PubMed

Rosen, Natalie O; Bergeron, Sophie; Glowacka, Maria; Delisle, Isabelle; Baxter, Mary Lou

2012-09-01

Provoked vestibulodynia (PVD) is a highly prevalent vulvovaginal pain condition that negatively affects women's emotional, sexual, and relationship well-being. Recent studies have investigated the role of interpersonal variables, including partner responses. We examined whether solicitous and facilitative partner responses were differentially associated with vulvovaginal pain and sexual satisfaction in women with PVD by examining each predictor while controlling for the other. One hundred twenty-one women (M age = 30.60, SD = 10.53) with PVD or self-reported symptoms of PVD completed the solicitous subscale of the spouse response scale of the Multidimensional Pain Inventory, and the facilitative subscale of the Spouse Response Inventory. Participants also completed measures of pain, sexual function, sexual satisfaction, trait anxiety, and avoidance of pain and sexual behaviors (referred to as "avoidance"). Dependent measures were the (i) Pain Rating Index of the McGill Pain Questionnaire with reference to pain during vaginal intercourse and (ii) Global Measure of Sexual Satisfaction Scale. Controlling for trait anxiety and avoidance, higher solicitous partner responses were associated with higher vulvovaginal pain intensity (β = 0.20, P = 0.03), and higher facilitative partner responses were associated with lower pain intensity (β = -0.20, P = 0.04). Controlling for sexual function, trait anxiety, and avoidance, higher facilitative partner responses were associated with higher sexual satisfaction (β = 0.15, P = 0.05). Findings suggest that facilitative partner responses may aid in alleviating vulvovaginal pain and improving sexual satisfaction, whereas solicitous partner responses may contribute to greater pain. © 2012 International Society for Sexual Medicine.

Parvovirus Minute Virus of Mice Induces a DNA Damage Response That Facilitates Viral Replication

PubMed Central

Adeyemi, Richard O.; Landry, Sebastien; Davis, Meredith E.; Weitzman, Matthew D.; Pintel, David J.

2010-01-01

Infection by DNA viruses can elicit DNA damage responses (DDRs) in host cells. In some cases the DDR presents a block to viral replication that must be overcome, and in other cases the infecting agent exploits the DDR to facilitate replication. We find that low multiplicity infection with the autonomous parvovirus minute virus of mice (MVM) results in the activation of a DDR, characterized by the phosphorylation of H2AX, Nbs1, RPA32, Chk2 and p53. These proteins are recruited to MVM replication centers, where they co-localize with the main viral replication protein, NS1. The response is seen in both human and murine cell lines following infection with either the MVMp or MVMi strains. Replication of the virus is required for DNA damage signaling. Damage response proteins, including the ATM kinase, accumulate in viral-induced replication centers. Using mutant cell lines and specific kinase inhibitors, we show that ATM is the main transducer of the signaling events in the normal murine host. ATM inhibitors restrict MVM replication and ameliorate virus-induced cell cycle arrest, suggesting that DNA damage signaling facilitates virus replication, perhaps in part by promoting cell cycle arrest. Thus it appears that MVM exploits the cellular DNA damage response machinery early in infection to enhance its replication in host cells. PMID:20949077

Set2 Methyltransferase Facilitates DNA Replication and Promotes Genotoxic Stress Responses through MBF-Dependent Transcription.

PubMed

Pai, Chen-Chun; Kishkevich, Anastasiya; Deegan, Rachel S; Keszthelyi, Andrea; Folkes, Lisa; Kearsey, Stephen E; De León, Nagore; Soriano, Ignacio; de Bruin, Robertus Antonius Maria; Carr, Antony M; Humphrey, Timothy C

2017-09-12

Chromatin modification through histone H3 lysine 36 methylation by the SETD2 tumor suppressor plays a key role in maintaining genome stability. Here, we describe a role for Set2-dependent H3K36 methylation in facilitating DNA replication and the transcriptional responses to both replication stress and DNA damage through promoting MluI cell-cycle box (MCB) binding factor (MBF)-complex-dependent transcription in fission yeast. Set2 loss leads to reduced MBF-dependent ribonucleotide reductase (RNR) expression, reduced deoxyribonucleoside triphosphate (dNTP) synthesis, altered replication origin firing, and a checkpoint-dependent S-phase delay. Accordingly, prolonged S phase in the absence of Set2 is suppressed by increasing dNTP synthesis. Furthermore, H3K36 is di- and tri-methylated at these MBF gene promoters, and Set2 loss leads to reduced MBF binding and transcription in response to genotoxic stress. Together, these findings provide new insights into how H3K36 methylation facilitates DNA replication and promotes genotoxic stress responses in fission yeast. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Moving forward on facilitation research: response to changing environments and effects on the diversity, functioning and evolution of plant communities

PubMed Central

Soliveres, Santiago; Smit, Christian; Maestre, Fernando T.

2015-01-01

Once seen as anomalous, facilitative interactions among plants and their importance for community structure and functioning are now widely recognized. The growing body of modelling, descriptive and experimental studies on facilitation covers a wide variety of terrestrial and aquatic systems throughout the globe. However, the lack of a general body of theory linking facilitation among different types of organisms and biomes and their responses to environmental changes prevents further advances in our knowledge regarding the evolutionary and ecological implications of facilitation in plant communities. Moreover, insights gathered from alternative lines of inquiry may substantially improve our understanding of facilitation, but these have been largely neglected thus far. Despite over 15 years of research and debate on this topic, there is no consensus on the degree to which plant–plant interactions change predictably along environmental gradients (i.e. the stress-gradient hypothesis), and this hinders our ability to predict how plant–plant interactions may affect the response of plant communities to ongoing global environmental change. The existing controversies regarding the response of plant–plant interactions across environmental gradients can be reconciled when clearly considering and determining the species-specificity of the response, the functional or individual stress type, and the scale of interest (pairwise interactions or community-level response). Here, we introduce a theoretical framework to do this, supported by multiple lines of empirical evidence. We also discuss current gaps in our knowledge regarding how plant–plant interactions change along environmental gradients. These include the existence of thresholds in the amount of species-specific stress that a benefactor can alleviate, the linearity or non-linearity of the response of pairwise interactions across distance from the ecological optimum of the beneficiary, and the need to explore

Moving forward on facilitation research: response to changing environments and effects on the diversity, functioning and evolution of plant communities.

PubMed

Soliveres, Santiago; Smit, Christian; Maestre, Fernando T

2015-02-01

Once seen as anomalous, facilitative interactions among plants and their importance for community structure and functioning are now widely recognized. The growing body of modelling, descriptive and experimental studies on facilitation covers a wide variety of terrestrial and aquatic systems throughout the globe. However, the lack of a general body of theory linking facilitation among different types of organisms and biomes and their responses to environmental changes prevents further advances in our knowledge regarding the evolutionary and ecological implications of facilitation in plant communities. Moreover, insights gathered from alternative lines of inquiry may substantially improve our understanding of facilitation, but these have been largely neglected thus far. Despite over 15 years of research and debate on this topic, there is no consensus on the degree to which plant-plant interactions change predictably along environmental gradients (i.e. the stress-gradient hypothesis), and this hinders our ability to predict how plant-plant interactions may affect the response of plant communities to ongoing global environmental change. The existing controversies regarding the response of plant-plant interactions across environmental gradients can be reconciled when clearly considering and determining the species-specificity of the response, the functional or individual stress type, and the scale of interest (pairwise interactions or community-level response). Here, we introduce a theoretical framework to do this, supported by multiple lines of empirical evidence. We also discuss current gaps in our knowledge regarding how plant-plant interactions change along environmental gradients. These include the existence of thresholds in the amount of species-specific stress that a benefactor can alleviate, the linearity or non-linearity of the response of pairwise interactions across distance from the ecological optimum of the beneficiary, and the need to explore further how

Selective processing of auditory evoked responses with iterative-randomized stimulation and averaging: A strategy for evaluating the time-invariant assumption.

PubMed

Valderrama, Joaquin T; de la Torre, Angel; Medina, Carlos; Segura, Jose C; Thornton, A Roger D

2016-03-01

The recording of auditory evoked potentials (AEPs) at fast rates allows the study of neural adaptation, improves accuracy in estimating hearing threshold and may help diagnosing certain pathologies. Stimulation sequences used to record AEPs at fast rates require to be designed with a certain jitter, i.e., not periodical. Some authors believe that stimuli from wide-jittered sequences may evoke auditory responses of different morphology, and therefore, the time-invariant assumption would not be accomplished. This paper describes a methodology that can be used to analyze the time-invariant assumption in jittered stimulation sequences. The proposed method [Split-IRSA] is based on an extended version of the iterative randomized stimulation and averaging (IRSA) technique, including selective processing of sweeps according to a predefined criterion. The fundamentals, the mathematical basis and relevant implementation guidelines of this technique are presented in this paper. The results of this study show that Split-IRSA presents an adequate performance and that both fast and slow mechanisms of adaptation influence the evoked-response morphology, thus both mechanisms should be considered when time-invariance is assumed. The significance of these findings is discussed. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Experimental Sleep Restriction Facilitates Pain and Electrically Induced Cortical Responses

PubMed Central

Matre, Dagfinn; Hu, Li; Viken, Leif A.; Hjelle, Ingri B.; Wigemyr, Monica; Knardahl, Stein; Sand, Trond; Nilsen, Kristian Bernhard

2015-01-01

Study Objectives: Sleep restriction (SR) has been hypothesized to sensitize the pain system. The current study determined whether experimental sleep restriction had an effect on experimentally induced pain and pain-elicited electroencephalographic (EEG) responses. Design: A paired crossover study. Intervention: Pain testing was performed after 2 nights of 50% SR and after 2 nights with habitual sleep (HS). Setting: Laboratory experiment at research center. Participants: Self-reported healthy volunteers (n = 21, age range: 18–31 y). Measurements and Results: Brief high-density electrical stimuli to the forearm skin produced pinprick-like pain. Subjective pain ratings increased after SR, but only in response to the highest stimulus intensity (P = 0.018). SR increased the magnitude of the pain-elicited EEG response analyzed in the time-frequency domain (P = 0.021). Habituation across blocks did not differ between HS and SR. Event-related desynchronization (ERD) was reduced after SR (P = 0.039). Pressure pain threshold of the trapezius muscle region also decreased after SR (P = 0.017). Conclusion: Sleep restriction (SR) increased the sensitivity to pressure pain and to electrically induced pain of moderate, but not low, intensity. The increased electrical pain could not be explained by a difference in habituation. Increased response magnitude is possibly related to reduced processing within the somatosensory cortex after partial SR. Citation: Matre D, Hu L, Viken LA, Hjelle IB, Wigemyr M, Knardahl S, Sand T, Nilsen KB. Experimental sleep restriction facilitates pain and electrically induced cortical responses. SLEEP 2015;38(10):1607–1617. PMID:26194577

Fatigueless response of spider draglines in cyclic torsion facilitated by reversible molecular deformation

NASA Astrophysics Data System (ADS)

Kumar, Bhupesh; Singh, Kamal P.

2014-11-01

We demonstrate that spider draglines exhibit a fatigueless response in extreme cyclic torsion up to its breaking limit. The well defined Raman bands at 1095 and 1245 cm-1 shifted linearly towards lower wavenumbers versus increasing twist in both clockwise and counter-clockwise directions. Under thousands of continuous loading cycles of twist strain approaching its breaking limit, all the Raman bands were preserved and the characteristic Raman peak shifts were found to be reversible. Besides, nanoscale surface profile of the worked silk appeared as good as the pristine silk. This unique fatigueless twist response of draglines, facilitated by reversible deformation of protein molecules, could find applications in durable miniatured devices.

Effects of vibration (G-jitters) on convection in micro-gravity

NASA Technical Reports Server (NTRS)

Wang, Francis C.

1994-01-01

To obtain high quality crystals, it is desirable to maintain a diffusion-limited transport process in a planar solidification surface between the solid and the melt during the crystal growth process. Due to the presence of buoyancy-driven convection, however, this situation is difficult to maintain on Earth. The microgravity environment of an orbiting space laboratory presents an alternative worth pursuing. With reduced gravity, convections very much suppressed in a space laboratory, making the environment more conducive for growing crystals with better quality. However, a space laboratory is not immune from any undesirable disturbances. Nonuniform and transient accelerations such as vibrations, g-jitters, and impulsive accelerations exist as a result of crew activities, space maneuvering, and the operations of on-board equipment. Measurements conducted on-board a U.S. Spacelab mission showed the existence of vibrations in the frequency range of 1 to 100 Hz. It was reported that a dominant mode of 17 Hz and harmonics of 54 Hz were observed and these were attributed to antenna operations. The vibration is not limited to any single plane but exists in all directions. Some data from the Russian MIR space station indicates the existence of vibration also at this frequency range.

Facilitators and obstacles in pre-hospital medical response to earthquakes: a qualitative study.

PubMed

Djalali, Ahmadreza; Khankeh, Hamidreza; Öhlén, Gunnar; Castrén, Maaret; Kurland, Lisa

2011-05-16

Earthquakes are renowned as being amongst the most dangerous and destructive types of natural disasters. Iran, a developing country in Asia, is prone to earthquakes and is ranked as one of the most vulnerable countries in the world in this respect. The medical response in disasters is accompanied by managerial, logistic, technical, and medical challenges being also the case in the Bam earthquake in Iran. Our objective was to explore the medical response to the Bam earthquake with specific emphasis on pre-hospital medical management during the first days. The study was performed in 2008; an interview based qualitative study using content analysis. We conducted nineteen interviews with experts and managers responsible for responding to the Bam earthquake, including pre-hospital emergency medical services, the Red Crescent, and Universities of Medical Sciences. The selection of participants was determined by using a purposeful sampling method. Sample size was given by data saturation. The pre-hospital medical service was divided into three categories; triage, emergency medical care and transportation, each category in turn was identified into facilitators and obstacles. The obstacles identified were absence of a structured disaster plan, absence of standardized medical teams, and shortage of resources. The army and skilled medical volunteers were identified as facilitators. The most compelling, and at the same time amenable obstacle, was the lack of a disaster management plan. It was evident that implementing a comprehensive plan would not only save lives but decrease suffering and enable an effective praxis of the available resources at pre-hospital and hospital levels.

Facilitators and obstacles in pre-hospital medical response to earthquakes: a qualitative study

PubMed Central

2011-01-01

Background Earthquakes are renowned as being amongst the most dangerous and destructive types of natural disasters. Iran, a developing country in Asia, is prone to earthquakes and is ranked as one of the most vulnerable countries in the world in this respect. The medical response in disasters is accompanied by managerial, logistic, technical, and medical challenges being also the case in the Bam earthquake in Iran. Our objective was to explore the medical response to the Bam earthquake with specific emphasis on pre-hospital medical management during the first days. Methods The study was performed in 2008; an interview based qualitative study using content analysis. We conducted nineteen interviews with experts and managers responsible for responding to the Bam earthquake, including pre-hospital emergency medical services, the Red Crescent, and Universities of Medical Sciences. The selection of participants was determined by using a purposeful sampling method. Sample size was given by data saturation. Results The pre-hospital medical service was divided into three categories; triage, emergency medical care and transportation, each category in turn was identified into facilitators and obstacles. The obstacles identified were absence of a structured disaster plan, absence of standardized medical teams, and shortage of resources. The army and skilled medical volunteers were identified as facilitators. Conclusions The most compelling, and at the same time amenable obstacle, was the lack of a disaster management plan. It was evident that implementing a comprehensive plan would not only save lives but decrease suffering and enable an effective praxis of the available resources at pre-hospital and hospital levels. PMID:21575233

A Middle School's Response-to-Intervention Journey: Building Systematic Processes of Facilitation, Collaboration, and Implementation

ERIC Educational Resources Information Center

Dulaney, Shannon K.

2013-01-01

This article discusses a qualitative case study examining one middle school's response to intervention (RtI) efforts. Study participants included the principal, assistant principal, and members of the school's leadership team. A description of the RtI consensus and infrastructure-building processes, consideration of the RtI facilitators, and a…

Response Inhibition Is Facilitated by a Change to Red Over Green in the Stop Signal Paradigm

PubMed Central

Blizzard, Shawn; Fierro-Rojas, Adriela; Fallah, Mazyar

2017-01-01

Actions are informed by the complex interactions of response execution and inhibition networks. These networks integrate sensory information with internal states and behavioral goals to produce an appropriate action or to update an ongoing action. Recent investigations have shown that, behaviorally, attention is captured through a hierarchy of colors. These studies showed how the color hierarchy affected visual processing. To determine whether the color hierarchy can be extended to higher level executive functions such as response execution and inhibition, we conducted several experiments using the stop-signal task (SST). In the first experiment, we modified the classic paradigm so that the go signals could vary in task-irrelevant color, with an auditory stop signal. We found that the task-irrelevant color of the go signals did not differentially affect response times. In the second experiment we determined that making the color of the go signal relevant for response selection still did not affect reaction times(RTs) and, thus, execution. In the third experiment, we modified the paradigm so that the stop signal was a task relevant change in color of the go signal. The mean RT to the red stop signal was approximately 25 ms faster than to the green stop signal. In other words, red stop signals facilitated response inhibition more than green stop signals, however, there was no comparative facilitation of response execution. These findings suggest that response inhibition, but not execution, networks are sensitive to differences in color salience. They also suggest that the color hierarchy is based on attentional networks and not simply on early sensory processing. PMID:28101011

Community Environmental Response Facilitation Act (CERFA) Report, Nike Battery Kansas City 30, Pleasant Hill, Missouri

DTIC Science & Technology

1994-04-01

environment . * A number of environmentally significant operation identified through Enhanced PA investigations have the potential to affect human health...and environment and represent areas requiring environmental evaluation. Additional investigation, such as sampling of a variety of media including...Best Available. Copy AD-A281 929 IIIIIIIIII•. Community Environmental Response Facilitation Act (CERFA) Report Nike Battery Kansas City 30 Pleasant

Chronic voluntary wheel running facilitates corticosterone response habituation to repeated audiogenic stress exposure in male rats

PubMed Central

SASSE, SARAH K.; GREENWOOD, BENJAMIN N.; MASINI, CHER V.; NYHUIS, TARA J.; FLESHNER, MONIKA; DAY, HEIDI E. W.; CAMPEAU, SERGE

2008-01-01

Voluntary exercise is associated with the prevention and treatment of numerous physical and psychological illnesses, yet the mechanisms by which it confers this protection remain unclear. In contrast, stress, particularly under conditions of prolonged or repeated exposure when glucocorticoid levels are consistently elevated, can have a devastating impact on health. It has been suggested that the benefits of physical exercise may lie in an ability to reduce some of the more deleterious health effects of stress and stress hormones. The present series of experiments provides evidence that voluntary exercise facilitates habituation of corticosterone but not adrenocorticotropin hormone responses to repeated stress presentations. After 6 weeks of running wheel access or sedentary housing conditions, rats were exposed to 11 consecutive daily 30 min presentations of 98 dB noise stress. Similar corticosterone responses in exercised rats and sedentary controls were observed following the first, acute stress presentation. While both groups demonstrated habituation of corticosterone secretory responses with repeated noise stress exposures, the rate of habituation was significantly facilitated in exercised animals. These results suggest that voluntary exercise may reduce the negative impact of prolonged or repeated stress on health by enhancing habituation of hypothalamo-pituitary–adrenocortical axis responses at the level of the adrenal cortex, ultimately reducing the amount of glucocorticoids the body and brain are exposed to. PMID:19065456

Managing piezoelectric sensor jitter: kinematic position tracking applications

NASA Astrophysics Data System (ADS)

Khomo, Malome T.

2016-02-01

Piezo-acoustic distance tracking sensors have challenges of reporting true distance readings. Challenges include directional anisotropy signal loss in transmission power and in receiver sensitivity, distance-related attenuation of signal and the phase shifts that result in jittery values, some preceding, and others succeeding the expected distance readings. There also exist signal time losses arising from dead time associated with processor latency, with carrier signal pulse length and with voltage rise-time delays in pulse detection. Together these factors cause distance under-reporting, and more critically, makes each reported value uncertain, which is unacceptable in distance-critical applications. Piezo-inertial accelerometers have equivalent if not more severe challenges in tri-axial configurations, for instance where a rotational tilt may happen under linear accelerative force. In the absence of tensor component adaptation to change of orientation, signal is lost until the next axial sensor detects it. Study paper focusses on piezo-acoustic transducers UCD1007 and 400SR160 (40kHz), used in a face-to-face configuration over a 600mm range. Within that range 10 successive phase shift wave fronts were identified, but it took 15 reconstructed wave fronts to uniquely identify a continuous end-to-end jitter-free and slippage-free kinematic data stream from the jittery sensor data. The additional 5 degrees of freedom were consumed by the 5-stage filter applied. The technique has remarkable combinatorial and projective geometry implications for digital sensor design. It is possible for the procedure to be applicable in 3-axis accelerometers and adapted into firmware for truly kinematic device driver interfaces so long as the reporting rates are matched with the user interface refresh rates. It is shown that acoustic transducer sensors require phase loop locking for kinematic continuity whereas gravimetric accelerometers demand better measurement time consistence in

Community Environmental Response Facilitation Act (CERFA) report, Fort George G. Mead, Maryland. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schultheisz, D.; Ward, L.

1994-04-01

This report presents the results of the Community Environmental Response Facilitation Act (CERFA) investigation conducted by Environmental Resources Management (ERM) at Fort George G. Meade (FGGM), a U.S. Government property selected for closure by the Base Realignment and Closure (BRAC) Commission. Under CERFA, Federal agencies are required to expeditiously identify real property that can be immediately reused and redeveloped. Satisfying this objective requires the identification of real property where no hazardous substances or petroleum products, regulated by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), were stored for one year or more, known to have been released, or disposed.more » Fort George G. Meade, CERFA, Base closure, BRAC.« less

Dissociation between unconscious motor response facilitation and conflict in medial frontal areas.

PubMed

D'Ostilio, Kevin; Garraux, Gaëtan

2012-01-01

Masked prime tasks have shown that sensory information that has not been consciously perceived can nevertheless modulate behavior. The neuronal correlates of behavioral manifestations of visuomotor priming remain debated, particularly with respect to the distribution and direction (i.e. increase or decrease) of activity changes in medial frontal areas. Here, we predicted that these discrepant results could be accounted for by two automatic and unconscious processes embedded in this task: response conflict and facilitation. We used event-related functional magnetic resonance imaging (fMRI), as 24 healthy participants had to respond, as fast as possible, to a target arrow presented immediately after a subliminal masked prime arrow. There were three experimental conditions defined by the prime-target relationship: compatible, incompatible, and neutral. The classical visuomotor priming effect was reproduced, with relatively longer reaction times (RTs) in incompatible trials. Longer RTs in incompatible than in neutral trials were specifically associated with stronger blood oxygen level-dependent (BOLD) activity in a conflict-related network comprising the anterior cingulate cortex and right frontal associative areas. Motor response facilitation as shown by shorter RTs in compatible than in neutral trials was associated with reduced activation in a motor preparation network including the medial and lateral premotor cortices, as a result of the repetition suppression of the fMRI BOLD signal. The present results provide new insights into automatic and unconscious visuomotor priming processes, suggesting an involvement of either a cognitive or motor network, depending on the prime-target relationship. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Method and apparatus for reducing spacecraft instrument induced jitter via multifrequency cancellation

NASA Technical Reports Server (NTRS)

Liu, Ketao (Inventor); Uetrecht, David S. (Inventor)

2002-01-01

A method, apparatus, article of manufacture, and a memory structure for compensating for instrument induced spacecraft jitter is disclosed. The apparatus comprises a spacecraft control processor for producing an actuator command signal, a signal generator, for producing a cancellation signal having at least one harmonic having a frequency and an amplitude substantially equal to that of a disturbance harmonic interacting with a spacecraft structural resonance and a phase substantially out of phase with the disturbance harmonic interacting with the spacecraft structural resonance, and at least one spacecraft control actuator, communicatively coupled to the spacecraft control processor and the signal generator for inducing satellite motion according to the actuator command signal and the cancellation signal. The method comprises the steps of generating a cancellation signal having at least one harmonic having a frequency and an amplitude substantially equal to that of a disturbance harmonic interacting with a spacecraft structural resonance and a phase substantially out of phase with the disturbance harmonic interacting with the spacecraft structural resonance, and providing the cancellation signal to a spacecraft control actuator. The apparatus comprises a storage device tangibly embodying the method steps described above.

Contribution of Ih to the relative facilitation of synaptic responses induced by carbachol in the entorhinal cortex during repetitive stimulation of the parasubiculum.

PubMed

Sparks, D W; Chapman, C A

2014-10-10

Neurons in the superficial layers of the entorhinal cortex provide the hippocampus with the majority of its cortical sensory input, and also receive the major output projection from the parasubiculum. This puts the parasubiculum in a position to modulate the activity of entorhinal neurons that project to the hippocampus. These brain areas receive cholinergic projections that are active during periods of theta- and gamma-frequency electroencephalographic (EEG) activity. The purpose of this study was to investigate how cholinergic receptor activation affects the strength of repetitive synaptic responses at these frequencies in the parasubiculo-entorhinal pathway and the cellular mechanisms involved. Whole-cell patch-clamp recordings of rat layer II medial entorhinal neurons were conducted using an acute slice preparation, and responses to 5-pulse trains of stimulation at theta- and gamma-frequency delivered to the parasubiculum were recorded. The cholinergic agonist carbachol (CCh) suppressed the amplitude of single synaptic responses, but also produced a relative facilitation of synaptic responses evoked during stimulation trains. The N-methyl-d-aspartate (NMDA) glutamate receptor blocker APV did not significantly reduce the relative facilitation effect. However, the hyperpolarization-activated cationic current (Ih) channel blocker ZD7288 mimicked the relative facilitation induced by CCh, suggesting that CCh-induced inhibition of Ih could produce the effect by increasing dendritic input resistance (Rin). Inward-rectifying and leak K(+) currents are known to interact with Ih to affect synaptic excitability. Application of the K(+) channel antagonist Ba(2+) depolarized neurons and enhanced temporal summation, but did not block further facilitation of train-evoked responses by ZD7288. The Ih-dependent facilitation of synaptic responses can therefore occur during reductions in inward-rectifying potassium current (IKir) associated with dendritic depolarization. Thus, in

If a Student Takes Control: Facilitator's Tasks and Responsibilities

NASA Astrophysics Data System (ADS)

Väljataga, Terje

This paper presents initial research results of an intervention into higher educational teaching and studying practices from facilitators‘ point of view. The intervention was implemented into an international Master’s level online course mediated by landscapes of social media tools and services. In this course more emphasis was put on a shift of control from a facilitator to a student or a group of students in the following aspects: setting up one’s study goals, choosing activities, selecting appropriate resources, including technology and defining one’s evaluation criteria. The initial analysis showed that the facilitators gained a lot in terms of understanding the benefits of exploiting social media tools and services for their teaching practices, perceiving a need of having a different role as well as the shortages and problems while being a facilitator in such a course.

Anticipating conflict facilitates controlled stimulus-response selection

PubMed Central

Correa, Ángel; Rao, Anling; Nobre, Anna C.

2014-01-01

Cognitive control can be triggered in reaction to previous conflict, as suggested by the finding of sequential effects in conflict tasks. Can control also be triggered proactively by presenting cues predicting conflict (‘proactive control’)? We exploited the high temporal resolution of event-related potentials (ERPs) and controlled for sequential effects to ask whether proactive control based on anticipating conflict modulates neural activity related to cognitive control, as may be predicted from the conflict-monitoring model. ERPs associated with conflict detection (N2) were measured during a cued flanker task. Symbolic cues were either informative or neutral with respect to whether the target involved conflicting or congruent responses. Sequential effects were controlled by analysing the congruency of the previous trial. The results showed that cuing conflict facilitated conflict resolution and reduced the N2 latency. Other potentials (frontal N1 and P3) were also modulated by cuing conflict. Cuing effects were most evident after congruent than after incongruent trials. This interaction between cuing and sequential effects suggests neural overlap between the control networks triggered by proactive and reactive signals. This finding clarifies why previous neuroimaging studies, in which reactive sequential effects were not controlled, have rarely found anticipatory effects upon conflict-related activity. Finally, the high temporal resolution of ERPs was critical to reveal a temporal modulation of conflict detection by proactive control. This novel finding suggests that anticipating conflict speeds up conflict detection and resolution. Recent research suggests that this anticipatory mechanism may be mediated by pre-activation of the ACC during the preparatory interval. PMID:18823248

Social information use in threat perception: Social buffering, contagion and facilitation of alarm responses

PubMed Central

Oliveira, Rui F.; Faustino, Ana I.

2017-01-01

ABSTRACT Group living animals can use the behavior of others as cues for the presence of threat in the environment and adjust their behavior accordingly. Therefore, different social phenomena that modulate the response to threat, such as social buffering, social transmission (contagion), and facilitation of alarm responses can be seen as different manifestations of social information use in threat detection. Thus, social phenomena that are functionally antagonistic, such as social buffering and social transmission of fear, may rely on shared neurobehavioral mechanisms related to the use of social information in decision-making about the presence of threat in the environment. Here, we propose a unifying conceptual framework for the study of social information use in threat perception based on signal detection theory.

Assessing facilitative responses to a nurse shrub at the community level: the example of Potentilla fruticosa in a sub-alpine grassland of northwest China.

PubMed

Xu, J; Michalet, R; Zhang, J-L; Wang, G; Chu, C-J; Xiao, S

2010-09-01

Biotic interaction studies have revealed a large discrepancy among experiments in target responses to the effects of neighbours, which may in part be due to both high species-specificity of plant responses and low number of target species used in experiments. Our aim was to assess facilitative responses at the community level and the role of both functional groups and ecological attributes of target species. In a sub-alpine grassland on the eastern Tibet plateau, we assessed growth responses of all species in the community to removal of a dominant shrub. We also measured changes in the main environmental variables. Species responses were analysed by functional group and in relation to their mean regional altitudinal distribution. All significant interactions were positive and affected one-third of the total species richness of the community. All functional groups were facilitated but forbs were less strongly facilitated than in the two other groups. High-alpine species were less strongly facilitated than low-sub-alpine species, but the strength of this relationship was weaker than that reported in previous work. There was evidence of a decrease in extreme temperatures below the canopy of the shrub but no variations in soil moisture. We conclude that the highly stressful conditions induced by the dry continental climate of the eastern Tibet plateau are a main driver of the exclusive dominance of positive interactions. Assessing interactive responses at the community level is likely to provide a useful tool to better understand the role of biotic interactions in community responses to environmental changes.

RE-PLAN: An Extensible Software Architecture to Facilitate Disaster Response Planning

PubMed Central

O’Neill, Martin; Mikler, Armin R.; Indrakanti, Saratchandra; Tiwari, Chetan; Jimenez, Tamara

2014-01-01

Computational tools are needed to make data-driven disaster mitigation planning accessible to planners and policymakers without the need for programming or GIS expertise. To address this problem, we have created modules to facilitate quantitative analyses pertinent to a variety of different disaster scenarios. These modules, which comprise the REsponse PLan ANalyzer (RE-PLAN) framework, may be used to create tools for specific disaster scenarios that allow planners to harness large amounts of disparate data and execute computational models through a point-and-click interface. Bio-E, a user-friendly tool built using this framework, was designed to develop and analyze the feasibility of ad hoc clinics for treating populations following a biological emergency event. In this article, the design and implementation of the RE-PLAN framework are described, and the functionality of the modules used in the Bio-E biological emergency mitigation tool are demonstrated. PMID:25419503

RISE-306; State Facilitator Program Evaluation, 1975-1976.

ERIC Educational Resources Information Center

Communication Technology Corp., Marlton, NJ.

As an arm of the National Diffusion Network, the Pennsylvania State Facilitator's responsibilities include informing the schools about Title III approved programs and aiding in the actual adoption of such programs by school districts. Two aspects of the facilitator's role were identified for evaluation: (1) whether the facilitator had implemented…

Facilitators in Ambivalence

ERIC Educational Resources Information Center

Karlsson, Mikael R.; Erlandson, Peter

2018-01-01

This is part of a larger ethnographical study concerning how school development in a local educational context sets cultural and social life in motion. The main data "in this article" consists of semi-structural interviews with teachers (facilitators) who have the responsibility of carrying out a project about formative assessment in…

Probabilistic model of nonlinear penalties due to collision-induced timing jitter for calculation of the bit error ratio in wavelength-division-multiplexed return-to-zero systems

NASA Astrophysics Data System (ADS)

Sinkin, Oleg V.; Grigoryan, Vladimir S.; Menyuk, Curtis R.

2006-12-01

We introduce a fully deterministic, computationally efficient method for characterizing the effect of nonlinearity in optical fiber transmission systems that utilize wavelength-division multiplexing and return-to-zero modulation. The method accurately accounts for bit-pattern-dependent nonlinear distortion due to collision-induced timing jitter and for amplifier noise. We apply this method to calculate the error probability as a function of channel spacing in a prototypical multichannel return-to-zero undersea system.

Community Environment Response Facilitation Act (CERFA) report, Cameron Station, Alexandria, VA. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

This report presents the results of the Community Environmental Response Facilitation Act (CERFA) Investigation Conducted by Environmental Resources Management (ERM) at Cameron Station, A U.S. Government property selected for closure by the Base Realignment and Closure (BRAC) Commission. Under CERFA, Federal agencies are required to identify expeditiously real property that can be immediately reused and redeveloped. Satisfying this objective requires the identification of real property where no hazardous substances or petroleum products, regulated by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), were stored for one year or more, known to have been released, or disposed. Cameron Station ismore » 169-acre site located in Alexandria, Virginia. Cameron Station was purchased by the Federal Government at the start of World War II. It has served primarily as a supply and administrative facility. The current mission is to provide support to the Commanding General of the Military District of Washington (MDW). Support functions of environmental significance include vehicle maintenance, print and paintshops, and photographic laboratories.« less

Reduction of timing jitter in a Q-Switched Nd:YAG laser by direct bleaching of a Cr4+:YAG saturable absorber.

PubMed

Cole, Brian; Goldberg, Lew; Trussell, C Ward; Hays, Alan; Schilling, Bradley W; McIntosh, Chris

2009-02-02

A method for optical triggering of a Q-switched Nd:YAG laser by direct bleaching of a Cr:YAG saturable absorber is described. This method involves the bleaching of a thin sheet of the saturable absorber from a direction orthogonal to the lasing axis using a single laser diode bar, where the Cr:YAG transmission increased from a non-bleached value of 47% to a bleached value of 63%. For steady state operation of a passively Q-switched laser (PRF=10 Hz), the pulse-to-pulse timing jitter showed approximately 12X reduction in standard deviation, from 241 nsec for free running operation to 20 nsec with optical triggering.

Transmission line transformer for reliable and low-jitter triggering of a railgap switch.

PubMed

Verma, Rishi; Mishra, Ekansh; Sagar, Karuna; Meena, Manraj; Shyam, Anurag

2014-09-01

The performance of railgap switch critically relies upon multichannel breakdown between the extended electrodes (rails) in order to ensure distributed current transfer along electrode length and to minimize the switch inductance. The initiation of several simultaneous arc channels along the switch length depends on the gap triggering technique and on the rate at which the electric field changes within the gap. This paper presents design, construction, and output characteristics of a coaxial cable based three-stage transmission line transformer (TLT) that is capable of initiating multichannel breakdown in a high voltage, low inductance railgap switch. In each stage three identical lengths of URM67 coaxial cables have been used in parallel and they have been wounded in separate cassettes to enhance the isolation of the output of transformer from the input. The cascaded output impedance of TLT is ~50 Ω. Along with multi-channel formation over the complete length of electrode rails, significant reduction in jitter (≤2 ns) and conduction delay (≤60 ns) has been observed by the realization of large amplitude (~80 kV), high dV/dt (~6 kV/ns) pulse produced by the indigenously developed TLT based trigger generator. The superior performance of TLT over conventional pulse transformer for railgap triggering application has been compared and demonstrated experimentally.

Hypnotically facilitated exposure response prevention therapy for an OIF veteran with OCD.

PubMed

Proescher, Eric J

2010-07-01

The highly stressful conditions of a war zone may exacerbate or trigger a wide variety of symptoms including Obsessive Compulsive Disorder (OCD) once a service member returns home. Service members and new veterans of the Iraq and Afghanistan wars present to treatment with multiple psychosocial concerns and co-morbid psychiatric conditions. Evidence-based treatments including exposure based therapies are commonly recommended for use with returning veterans. Although studies support the efficacy of Exposure Response Prevention (ERP) therapy for treating OCD, eligibility for these studies limits participation to subjects who self-report a well-defined, circumscribed complaint. This approach is not typical of clinic clients who, more often than not, report multiple psychological issues. The following individual case study demonstrates how integrating hypnosis facilitated the cognitive-behavioral ERP therapy and treatment for a patient suffering from OCD.

The Role of Touch in Facilitated Communication.

ERIC Educational Resources Information Center

Kezuka, Emiko

1997-01-01

A study investigated the role of touch in the use of facilitated communication with Japanese individuals with autism. Five experiments were conducted involving a "telepathy game" using a rod with an attached strain gauge. Results found the facilitator's contact controlled the motor responses of the subjects. (Author/CR)

The relationship between facilitators' questions and the level of reflection in postsimulation debriefing.

PubMed

Husebø, Sissel Eikeland; Dieckmann, Peter; Rystedt, Hans; Søreide, Eldar; Friberg, Febe

2013-06-01

Simulation-based education is a learner-active method that may enhance teamwork skills such as leadership and communication. The importance of postsimulation debriefing to promote reflection is well accepted, but many questions concerning whether and how faculty promote reflection remain largely unanswered in the research literature. The aim of this study was therefore to explore the depth of reflection expressed in questions by facilitators and responses from nursing students during postsimulation debriefings. Eighty-one nursing students and 4 facilitators participated. The data were collected in February and March 2008, the analysis being conducted on 24 video-recorded debriefings from simulated resuscitation teamwork involving nursing students only. Using Gibbs' reflective cycle, we graded the facilitators' questions and nursing students' responses into stages of reflection and then correlated these. Facilitators asked most evaluative and fewest emotional questions, whereas nursing students answered most evaluative and analytic responses and fewest emotional responses. The greatest difference between facilitators and nursing students was in the analytic stage. Only 23 (20%) of 117 questions asked by the facilitators were analytic, whereas 45 (35%) of 130 students' responses were rated as analytic. Nevertheless, the facilitators' descriptive questions also elicited student responses in other stages such as evaluative and analytic responses. We found that postsimulation debriefings provide students with the opportunity to reflect on their simulation experience. Still, if the debriefing is going to pave the way for student reflection, it is necessary to work further on structuring the debriefing to facilitate deeper reflection. Furthermore, it is important that facilitators consider what kind of questions they ask to promote reflection. We think future research on debriefing should focus on developing an analytical framework for grading reflective questions. Such

A scheme for a shot-to-shot, femtosecond-resolved pulse length and arrival time measurement of free electron laser x-ray pulses that overcomes the time jitter problem between the FEL and the laser

NASA Astrophysics Data System (ADS)

Juranić, P. N.; Stepanov, A.; Peier, P.; Hauri, C. P.; Ischebeck, R.; Schlott, V.; Radović, M.; Erny, C.; Ardana-Lamas, F.; Monoszlai, B.; Gorgisyan, I.; Patthey, L.; Abela, R.

2014-03-01

The recent entry of X-ray free electron lasers (FELs) to all fields of physics has created an enormous need, both from scientists and operators, for better characterization of the beam created by these facilities. Of particular interest is the measurement of the arrival time of the FEL pulse relative to a laser pump, for pump-probe experiments, and the measurement of the FEL pulse length. This article describes a scheme that corrects one of the major sources of uncertainty in these types of measurements, namely the jitter in the arrival time of the FEL relative to an experimental laser beam. The setup presented here uses a combination of THz streak cameras and a spectral encoding setup to reduce the effect of an FEL's jitter, leaving the pulse length as the only variable that can affect the accuracy of the pulse length and arrival time measurement. A discussion of underlying principles is also provided.

Exosome-mediated miR-146a transfer suppresses type I interferon response and facilitates EV71 infection

PubMed Central

Fu, Yuxuan; Zhang, Li; Zhang, Fang; Tang, Ting; Zhou, Qi; Feng, Chunhong; Jin, Yu

2017-01-01

Exosomes can transfer genetic materials between cells. Their roles in viral infections are beginning to be appreciated. Researches have shown that exosomes released from virus-infected cells contain a variety of viral and host cellular factors that are able to modulate recipient’s cellular response and result in productive infection of the recipient host. Here, we showed that EV71 infection resulted in upregulated exosome secretion and differential packaging of the viral genomic RNA and miR-146a into exosomes. We provided evidence showing that miR-146a was preferentially enriched in exosomes while the viral RNA was not in infected cells. Moreover, the exosomes contained replication-competent EV71 RNA in complex with miR-146a, Ago2, and GW182 and could mediate EV71 transmission independent of virus-specific receptor. The exosomal viral RNA could be transferred to and replicate in a new target cell while the exosomal miR-146a suppressed type I interferon response in the target cell, thus facilitating the viral replication. Additionally, we found that the IFN-stimulated gene factors (ISGs), BST-2/tetherin, were involved in regulating EV71-induced upregulation of exosome secretion. Importantly, in vivo study showed that exosomal viral RNA exhibited differential tissue accumulation as compared to the free virus particles. Together, our findings provide evidence that exosomes secreted by EV71-infected cells selectively packaged high level miR-146a that can be functionally transferred to and facilitate exosomal EV71 RNA to replicate in the recipient cells by suppressing type I interferon response. PMID:28910400

An oxytocin-induced facilitation of neural and emotional responses to social touch correlates inversely with autism traits.

PubMed

Scheele, Dirk; Kendrick, Keith M; Khouri, Christoph; Kretzer, Elisa; Schläpfer, Thomas E; Stoffel-Wagner, Birgit; Güntürkün, Onur; Maier, Wolfgang; Hurlemann, René

2014-08-01

Social communication through touch and mutual grooming can convey highly salient socio-emotional signals and has been shown to involve the neuropeptide oxytocin (OXT) in several species. Less is known about the modulatory influence of OXT on the neural and emotional responses to human interpersonal touch. The present randomized placebo (PLC)-controlled within-subject pharmaco-functional magnetic resonance imaging (fMRI) study was designed to test the hypothesis that a single intranasal dose of synthetic OXT (24 IU) would facilitate both neural and emotional responses to interpersonal touch in a context- (female vs male touch) and trait- (autistic trait load) specific manner. Specifically, the experimental rationale was to manipulate the reward value of interpersonal touch independent of the intensity and type of actual cutaneous stimulation administered. Thus, 40 heterosexual males believed that they were touched by either a man or a woman, although in fact an identical pattern of touch was always given by the same female experimenter blind to condition type. Our results show that OXT increased the perceived pleasantness of female, but not male touch, and associated neural responses in insula, precuneus, orbitofrontal, and pregenual anterior cingulate cortex. Moreover, the behavioral and neural effects of OXT were negatively correlated with autistic-like traits. Taken together, this is the first study to show that the perceived hedonic value of human heterosexual interpersonal touch is facilitated by OXT in men, but that its behavioral and neural effects in this context are blunted in individuals with autistic traits.

Transmission line transformer for reliable and low-jitter triggering of a railgap switch

NASA Astrophysics Data System (ADS)

Verma, Rishi; Mishra, Ekansh; Sagar, Karuna; Meena, Manraj; Shyam, Anurag

2014-09-01

The performance of railgap switch critically relies upon multichannel breakdown between the extended electrodes (rails) in order to ensure distributed current transfer along electrode length and to minimize the switch inductance. The initiation of several simultaneous arc channels along the switch length depends on the gap triggering technique and on the rate at which the electric field changes within the gap. This paper presents design, construction, and output characteristics of a coaxial cable based three-stage transmission line transformer (TLT) that is capable of initiating multichannel breakdown in a high voltage, low inductance railgap switch. In each stage three identical lengths of URM67 coaxial cables have been used in parallel and they have been wounded in separate cassettes to enhance the isolation of the output of transformer from the input. The cascaded output impedance of TLT is ˜50 Ω. Along with multi-channel formation over the complete length of electrode rails, significant reduction in jitter (≤2 ns) and conduction delay (≤60 ns) has been observed by the realization of large amplitude (˜80 kV), high dV/dt (˜6 kV/ns) pulse produced by the indigenously developed TLT based trigger generator. The superior performance of TLT over conventional pulse transformer for railgap triggering application has been compared and demonstrated experimentally.

Spectral summation and facilitation in on- and off-responses for optimized representation of communication calls in mouse inferior colliculus.

PubMed

Akimov, Alexander G; Egorova, Marina A; Ehret, Günter

2017-02-01

Selectivity for processing of species-specific vocalizations and communication sounds has often been associated with the auditory cortex. The midbrain inferior colliculus, however, is the first center in the auditory pathways of mammals integrating acoustic information processed in separate nuclei and channels in the brainstem and, therefore, could significantly contribute to enhance the perception of species' communication sounds. Here, we used natural wriggling calls of mouse pups, which communicate need for maternal care to adult females, and further 15 synthesized sounds to test the hypothesis that neurons in the central nucleus of the inferior colliculus of adult females optimize their response rates for reproduction of the three main harmonics (formants) of wriggling calls. The results confirmed the hypothesis showing that average response rates, as recorded extracellularly from single units, were highest and spectral facilitation most effective for both onset and offset responses to the call and call models with three resolved frequencies according to critical bands in perception. In addition, the general on- and/or off-response enhancement in almost half the investigated 122 neurons favors not only perception of single calls but also of vocalization rhythm. In summary, our study provides strong evidence that critical-band resolved frequency components within a communication sound increase the probability of its perception by boosting the signal-to-noise ratio of neural response rates within the inferior colliculus for at least 20% (our criterion for facilitation). These mechanisms, including enhancement of rhythm coding, are generally favorable to processing of other animal and human vocalizations, including formants of speech sounds. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

G-Jitter Induced Magnetohydrodynamics Flow of Nanofluid with Constant Convective Thermal and Solutal Boundary Conditions

PubMed Central

Uddin, Mohammed J.; Khan, Waqar A.; Ismail, Ahmad Izani Md.

2015-01-01

Taking into account the effect of constant convective thermal and mass boundary conditions, we present numerical solution of the 2-D laminar g-jitter mixed convective boundary layer flow of water-based nanofluids. The governing transport equations are converted into non-similar equations using suitable transformations, before being solved numerically by an implicit finite difference method with quasi-linearization technique. The skin friction decreases with time, buoyancy ratio, and thermophoresis parameters while it increases with frequency, mixed convection and Brownian motion parameters. Heat transfer rate decreases with time, Brownian motion, thermophoresis and diffusion-convection parameters while it increases with the Reynolds number, frequency, mixed convection, buoyancy ratio and conduction-convection parameters. Mass transfer rate decreases with time, frequency, thermophoresis, conduction-convection parameters while it increases with mixed convection, buoyancy ratio, diffusion-convection and Brownian motion parameters. To the best of our knowledge, this is the first paper on this topic and hence the results are new. We believe that the results will be useful in designing and operating thermal fluids systems for space materials processing. Special cases of the results have been compared with published results and an excellent agreement is found. PMID:25933066

Improvement of dem Generation from Aster Images Using Satellite Jitter Estimation and Open Source Implementation

NASA Astrophysics Data System (ADS)

Girod, L.; Nuth, C.; Kääb, A.

2015-12-01

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) system embarked on the Terra (EOS AM-1) satellite has been a source of stereoscopic images covering the whole globe at a 15m resolution at a consistent quality for over 15 years. The potential of this data in terms of geomorphological analysis and change detection in three dimensions is unrivaled and needs to be exploited. However, the quality of the DEMs and ortho-images currently delivered by NASA (ASTER DMO products) is often of insufficient quality for a number of applications such as mountain glacier mass balance. For this study, the use of Ground Control Points (GCPs) or of other ground truth was rejected due to the global "big data" type of processing that we hope to perform on the ASTER archive. We have therefore developed a tool to compute Rational Polynomial Coefficient (RPC) models from the ASTER metadata and a method improving the quality of the matching by identifying and correcting jitter induced cross-track parallax errors. Our method outputs more accurate DEMs with less unmatched areas and reduced overall noise. The algorithms were implemented in the open source photogrammetric library and software suite MicMac.

Community Environmental Response Facilitation Act

EPA Pesticide Factsheets

To amend the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 to require the Federal Government, before termination of Federal activities on any real property owned by the Government, to identify real property where no hazardous substance was stored, released, or disposed of.

80-GHz AlGaInAs/InP 1.55 μm colliding-pulse mode-locked laser with low divergence angle and timing jitter

NASA Astrophysics Data System (ADS)

Hou, L. P.; Haji, M.; Li, C.; Qiu, B. C.; Bryce, A. C.

2011-07-01

We present an 80-GHz λ ~ 1.55 μm passively colliding-pulse mode-locked laser based on a novel AlGaInAs/InP epitaxial structure, which consists of a strained 3-quantum-well active layer incorporated with a passive far-field reduction layer. The device generated 910 fs pulses with a state-of-art timing jitter value of 190 fs (4 - 80 MHz), while demonstrating a low divergence angle (12.7°×26.3°) with two fold butt coupling efficiency to a flat cleaved single mode fiber when compared with the conventional mode-locked laser.

Event-related potentials dissociate facilitation and interference effects in the numerical Stroop paradigm.

PubMed

Szucs, Dénes; Soltész, Fruzsina

2007-11-05

In the numerical Stroop paradigm (NSP) participants compare simultaneously presented Arabic digits based on either their numerical or on their physical size dimension. Responses are faster when the numerical and size dimensions are congruent with each other (facilitation), and responses are slower when the numerical and size dimensions are incongruent with each other (interference). We aimed to find out whether facilitation and interference appears during the course of perceptual or response processing. To this end, facilitation and interference effects in the amplitude of event-related brain potentials (ERPs) were examined. The onset of motor preparation was determined by monitoring the lateralized readiness potential. In numerical comparison one facilitation effect was related to perceptual processing at the level of the magnitude representation. A second facilitation effect and interference effects appeared during response processing. In size comparison facilitation and interference appeared exclusively during response processing. In both tasks, ERP interference effects were probably related to contextual analysis and to the conflict monitoring and selection for action activity of the anterior cingulate cortex. The results demonstrate that facilitation and interference effects in the NSP appear during multiple stages of processing, and that they are related to different cognitive processes. Therefore these effects should be clearly separated in studies of the NSP. A model of the processes involved in the NSP is provided and implications for studies of the NSP are drawn.

Community Environmental Response Facilitation Act (CERFA) report, Fort Benjamin Harrison, Indiana. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1994-04-01

Fort Benjamin Harrison (FBH) has been investigated by Arthur D. Little, Inc. under the Community Environmental Response Facilitation Act (CERFA). FBH is located 12 miles northeast of downtown Indianapolis, Indiana. The installation's mission includes administrative and training activities. The objective of CERFA is to expeditiously identify real property offering the greatest opportunity for immediate reuse and redevelopment. This investigation included interviews, visual inspections, and review of existing documents, regulatory records, data bases, and title documents. This information was used to divide the installation into four categories of parcels. CERFA parcels approximately 1,825 acres of the facility have no history ofmore » Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) regulated hazardous substance or petroleum product release, disposal, or storage. CERFA parcels with qualifiers approximately 78 acres had no evidence of such release, disposal, or storage, but contained non-CERCLA hazards, such as asbestos or radon. CERFA disqualified parcels for approximately 399 acres of the investigated areas there is a history of release, disposal, or storage for one year or more of CERCLA-regulated hazardous substances or petroleum products; and CERFA excluded parcels approximately 201 acres have an existing mandate for retention by the federal government or have already been designated for transfer.« less

Emotion processing facilitates working memory performance.

PubMed

Lindström, Björn R; Bohlin, Gunilla

2011-11-01

The effect of emotional stimulus content on working memory performance has been investigated with conflicting results, as both emotion-dependent facilitation and impairments are reported in the literature. To clarify this issue, 52 adult participants performed a modified visual 2-back task with highly arousing positive stimuli (sexual scenes), highly arousing negative stimuli (violent death) and low-arousal neutral stimuli. Emotional stimulus processing was found to facilitate task performance relative to that of neutral stimuli, both in regards to response accuracy and reaction times. No emotion-dependent differences in false-alarm rates were found. These results indicate that emotional information can have a facilitating effect on working memory maintenance and processing of information.

Facilitating Conceptual Change in Students' Understanding of Electrochemistry.

ERIC Educational Resources Information Center

Niaz, Mansoor

2002-01-01

Constructs a teaching strategy to facilitate conceptual change in freshman students' understanding of electrochemistry. Provides students with the correct response along with alternative responses (teaching experiments), producing a conflicting situation that is conducive to an equilibration of their cognitive structures. Concludes that the…

Caregivers' responses to an intervention to improve young child feeding behaviors in rural Bangladesh: a mixed method study of the facilitators and barriers to change.

PubMed

Affleck, William; Pelto, Gretel

2012-08-01

Behavior change communications regarding child feeding have met with mixed success. The present study analyzes responses of 34 Bangladeshi caregivers seven months after they received a responsive feeding intervention. The intervention communicated and demonstrated five feeding interactions: hand-washing, self-feeding, verbal responsivity, managing refusals non-forcefully, and dietary diversity. Seventeen caregivers who adopted key behaviors addressed by the intervention and 17 who did not were compared in terms of socio-demographic variables, but more importantly in terms of their recall of the messages, their reported practice, and reported facilitators and barriers. Both those who changed and those who did not reported similar facilitators and barriers to practicing the new behaviors; there was also no difference in recall or in socio-demographic variables. Key themes identified through a constant comparative analysis helped to focus on common features of the lives of caregivers that made it easy or difficult to perform the practices. Some of these were household constraints such as poverty, shortage of time in which to complete chores, and avoiding waste and messiness; others related to the child's demands. Many caregivers misinterpreted instructions about talking to one's child in response to signals, as opposed to more common forms of supervision. Facilitators such as the child's evident pleasure and the caregiver's satisfaction did not always outweigh the barriers. Recommendations for improving interventions include helping caregivers solve problems tied to barriers and including more family members in the intervention. Copyright © 2012 Elsevier Ltd. All rights reserved.

Perceived Facilitators and Barriers to Local Health Department Workers' Participation in Infectious Disease Emergency Responses.

PubMed

Rutkow, Lainie; Paul, Amy; Taylor, Holly A; Barnett, Daniel J

Local health departments play a key role in emergency preparedness and respond to a wide range of threats including infectious diseases such as seasonal influenza, tuberculosis, H1N1, Ebola virus disease, and Zika virus disease. To successfully respond to an infectious disease outbreak, local health departments depend upon the participation of their workforce; yet, studies indicate that sizable numbers of workers would not participate in such a response. The reasons why local health department workers participate, or fail to participate, in infectious disease responses are not well understood. To understand why local health department workers are willing, or not willing, to report to work during an infectious disease response. From April 2015 to January 2016, we conducted 28 semistructured interviews with local health department directors, preparedness staff, and nonpreparedness staff. Interviews were conducted with individuals throughout the United States. We interviewed 28 individuals across 3 groups: local health department directors (n = 8), preparedness staff (n = 10), and nonpreparedness staff (n = 10). Individuals' descriptions of why local health department workers are willing, or not willing, to report to work during an infectious disease response. Factors that facilitate willingness to respond to an infectious disease emergency included availability of vaccines and personal protective equipment; flexible work schedule and childcare arrangements; information sharing via local health department trainings; and perceived commitments to one's job and community. Factors that hinder willingness to respond to an infectious disease emergency included potential disease exposure for oneself and one's family; logistical considerations for care of children, the elderly, and pets; and perceptions about one's role during an infectious disease response. Our findings highlight opportunities for local health departments to revisit their internal policies and engage in

In Search of Cross-Talk Facilitation in a Dual-Cued Recall Task

ERIC Educational Resources Information Center

Rickard, Timothy C.; Bajic, Daniel

2005-01-01

Despite earlier evidence that the presence of 2 redundant cues can facilitate activation of a common response, T. C. Rickard and D. Bajic (2004) found no dual-cue facilitation in the case of cued recall, provided that each cue-response association was learned independently. In this study the authors investigated the generality of their results…

Using Simulation in Nursing PhD Education: Facilitating Application of Responsible Conduct of Research Principles.

PubMed

Clayton, Margaret F; Supiano, Katherine; Wilson, Rebecca; Lassche, Madeline; Latendresse, Gwen

Simulation is a standard clinical nursing educational approach; however, simulation is rarely used in nonclinical nursing education. In doctor of philosophy (PhD) programs, ethical content about responsible conduct of research (RCR) is traditionally didactic, presented early in the program of study. Ethics content merits review before students begin the dissertation phase; thus, the purpose of this project was to design and implement simulated scenarios to help students apply RCR principles prior to beginning independent research. Two scenarios were developed: (a) a potential protocol change discussed in a research team meeting and (b) an in-home data collection experience with an elderly participant and her daughter. Actors were trained faculty volunteers, playing roles outside their usual academic positions. Faculty facilitated scenarios by posing questions as cues related to desired learning outcomes as scenarios unfolded. Eleven nursing PhD students and 6 faculty participated. Debriefing facilitated discussion of RCR principles, common research quandaries, and suggested scenario revisions. Faculty, expert observation, and video-review showed that younger and less experienced students tried to give the "right" answer rather than implement RCR appropriate solutions. Students with more clinical experience had difficulty adopting the less familiar researcher role. Overall, simulation is a novel and useful way to enhance RCR content in PhD programs. Copyright © 2016 Elsevier Inc. All rights reserved.

Cigarette smoke silences innate lymphoid cell function and facilitates an exacerbated type I interleukin-33-dependent response to infection.

PubMed

Kearley, Jennifer; Silver, Jonathan S; Sanden, Caroline; Liu, Zheng; Berlin, Aaron A; White, Natalie; Mori, Michiko; Pham, Tuyet-Hang; Ward, Christine K; Criner, Gerard J; Marchetti, Nathaniel; Mustelin, Tomas; Erjefalt, Jonas S; Kolbeck, Roland; Humbles, Alison A

2015-03-17

Cigarette smoking is a major risk factor for chronic obstructive pulmonary disease and is presumed to be central to the altered responsiveness to recurrent infection in these patients. We examined the effects of smoke priming underlying the exacerbated response to viral infection in mice. Lack of interleukin-33 (IL-33) signaling conferred complete protection during exacerbation and prevented enhanced inflammation and exaggerated weight loss. Mechanistically, smoke was required to upregulate epithelial-derived IL-33 and simultaneously alter the distribution of the IL-33 receptor ST2. Specifically, smoke decreased ST2 expression on group 2 innate lymphoid cells (ILC2s) while elevating ST2 expression on macrophages and natural killer (NK) cells, thus altering IL-33 responsiveness within the lung. Consequently, upon infection and release, increased local IL-33 significantly amplified type I proinflammatory responses via synergistic modulation of macrophage and NK cell function. Therefore, in COPD, smoke alters the lung microenvironment to facilitate an alternative IL-33-dependent exaggerated proinflammatory response to infection, exacerbating disease. Copyright © 2015 Elsevier Inc. All rights reserved.

Nurturing Responsible Behavior: A Foundation for Guidance. Preventing Discipline Problems, Unit 3. [Teaching Video, Practice Video, Facilitator's Guide, and Viewer's Guide].

ERIC Educational Resources Information Center

2000

As children learn to practice responsible behaviors, discipline problems in the early childhood classroom can be reduced. As Part 3 of a 3-part video series designed to help adults working with 3- to 8-year-olds use a proactive approach to prevent discipline problems, this video training package is comprised of a Facilitators' Guide, a Viewers'…

Systems for measuring response statistics of gigahertz bandwidth photomultipliers

NASA Technical Reports Server (NTRS)

Abshire, J. B.; Rowe, H. E.

1977-01-01

New systems have been developed for measuring the average impulse response, the pulse-height spectrum, the transit-time statistics as a function of signal level, and the dark-count spectrum of gigahertz bandwidth photomultipliers. Measurements showed that the 0.53 microns pulse used as an optical test source had a 30 picoseconds and less than 70 ps pulse width. Calibration data showed the system resolution to be less than 20 ps for root mean square transit-time measurements. Test data for a static crossed-field photomultiplier showed 2-photoelectron resolution and less than 30-ps time jitter over the 1- to 100-photoelectron range.

Exposure levels for chemical threat compounds: information to facilitate chemical incident response.

PubMed

Hauschild, Veronique D; Watson, Annetta

2013-01-01

Although not widely known, a robust set of peer-reviewed public health and occupational exposure levels presently exist for key chemical warfare agents (CWAs) and certain acutely toxic industrial chemicals (TICs) identified as terrorist attack threats. Familiarity with these CWA and TIC exposure levels and their historic applications has facilitated emergency management decision-making by public and environmental health decision-makers. Specifically, multiple air, soil, and water exposure levels for CWAs and TICs summarized here have been extensively peer-reviewed and published; many have been recognized and are in use by federal and state health agencies as criteria for hazard zone prediction and assessment, occupational safety, and "how clean is clean enough" decisions. The key, however, is to know which criteria are most appropriate for specific decisions. While public safety is critical, high levels of concern often associated with perceived or actual proximity to extremely toxic chemical agents could result in overly cautious decisions that generate excessive delays, expenditure of scarce resources, and technological difficulties. Rapid selection of the most appropriate chemical exposure criteria is recommended to avoid such problems and expedite all phases of chemical incident response and recovery.

Facilitating Facilitators: Enhancing PBL through a Structured Facilitator Development Program

ERIC Educational Resources Information Center

Salinitri, Francine D.; Wilhelm, Sheila M.; Crabtree, Brian L.

2015-01-01

With increasing adoption of the problem-based learning (PBL) model, creative approaches to enhancing facilitator training and optimizing resources to maintain effective learning in small groups is essential. We describe a theoretical framework for the development of a PBL facilitator training program that uses the constructivist approach as the…

Suppressive and Facilitative Effects of Shock Intensity and Interresponse Times Followed by Shock

ERIC Educational Resources Information Center

Everly, Jessica B.; Perone, Michael

2012-01-01

Although response-dependent shock often suppresses responding, response facilitation can occur. In two experiments, we examined the suppressive and facilitative effects of shock by manipulating shock intensity and the interresponse times that produced shock. Rats' lever presses were reinforced on a variable-interval 40-s schedule of food…

Lessons from the Chilean earthquake: how a human rights framework facilitates disaster response.

PubMed

Arbour, MaryCatherine; Murray, Kara; Arriet, Felipe; Moraga, Cecilia; Vega, Miguel Cordero

2011-07-14

The earthquake of 2010 in Chile holds important lessons about how a rights-based public health system can guide disaster response to protect vulnerable populations. This article tells the story of Chile Grows With You (Chile Crece Contigo), an intersectoral system created three years before the earthquake for protection of child rights and development, and its role in the disaster response. The creation of Chile Grows With You with an explicit rights-oriented mandate established intersectoral mechanisms, relationships, and common understanding between governmental groups at the national and local levels. After the earthquake, Chile Grows With You organized its activities according to its founding principles: it provided universal access and support for all Chilean children, with special attention and services for those at greatest risk. This tiered approach involved public health and education materials for all children and families; epidemiologic data for local planners about children in their municipalities at-risk before the earthquake; and an instrument developed to assist in the assessment and intervention of children put at risk by the earthquake. This disaster response illustrates how a rights-based framework defined and operationalized in times of stability facilitated organization, prioritization, and sustained action to protect and support children and families in the acute aftermath of the earthquake, despite a change in government from a left-wing to a right-wing president, and into the early recovery period. Copyright © 2011 Arbour, Murray, Arriet, Moraga, and Vega. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited.

Three-dimensional FLASH Laser Radar Range Estimation via Blind Deconvolution

DTIC Science & Technology

2009-10-01

scene can result in errors due to several factors including the optical spatial impulse response, detector blurring, photon noise , timing jitter, and...estimation error include spatial blur, detector blurring, noise , timing jitter, and inter-sample targets. Unlike previous research, this paper ac- counts...for pixel coupling by defining the range image mathematical model as a 2D convolution between the system spatial impulse response and the object (target

Clinical education facilitators: a literature review.

PubMed

Lambert, Veronica; Glacken, Michèle

2005-07-01

The aim of this literature review, set within an Irish context, is to present a broad overview of former and existing clinical support personnel, explore the concept of facilitation and examine what is known about the role of the clinical education facilitator. The importance of providing a supportive clinical environment to enhance clinical teaching and learning is strongly portrayed in the literature. While the past two decades have borne witness to various clinical support personnel, the literature identifies conflicting demands that these personnel face. No suggestions are advanced as to how to overcome these difficulties, which inevitably influence the quality and quantity of their clinical teaching role. An identifiable gap exists over who has prime responsibility for clinical teaching. It is timely that alternative possibilities for organizing clinical teaching are investigated. A new post emerging in practice settings is that of the clinical education facilitator who is meant to be the key linchpin in clinical areas for reducing the theory-practice gap. Relevant literature for this review was sourced using the computerized databases CINAHL, Medline and Synergy. Manual searching of relevant nursing journals and sourcing of secondary references extended the search. Government reports and other relevant documents were obtained through pertinent websites. Papers that explicitly examined the concept of facilitation and explored the posts of clinical education facilitators were included; six research papers were accessed and reviewed. In addition seven non-empirical papers were included. It is clear that considerable lack of role clarity resides over what constitutes clinical facilitation and the role of the clinical facilitator. Thus, it is paramount to strengthen this support role with Irish empirical evidence. A major advantage in having a ward-based clinical education facilitator is the benefit of having access to someone who can concentrate solely on

What can we learn from facilitator and student perceptions of facilitation skills and roles in the first year of a problem-based learning curriculum?

PubMed Central

McLean, Michelle

2003-01-01

Background The small group tutorial is a cornerstone of problem-based learning. By implication, the role of the facilitator is of pivotal importance. The present investigation canvassed perceptions of facilitators with differing levels of experience regarding their roles and duties in the tutorial. Methods In January 2002, one year after problem-based learning implementation at the Nelson R. Mandela School of Medicine, facilitators with the following experience were canvassed: trained and about to facilitate, facilitated once only and facilitated more than one six-week theme. Student comments regarding facilitator skills were obtained from a 2001 course survey. Results While facilitators generally agreed that the three-day training workshop provided sufficient insight into the facilitation process, they become more comfortable with increasing experience. Many facilitators experienced difficulty not providing content expertise. Again, this improved with increasing experience. Most facilitators saw students as colleagues. They agreed that they should be role models, but were less enthusiastic about being mentors. Students were critical of facilitators who were not up to date with curriculum implementation or who appeared disinterested. While facilitator responses suggest that there was considerable intrinsic motivation, this might in fact not be the case. Conclusions Even if they had facilitated on all six themes, facilitators could still be considered as novices. Faculty support is therefore critical for the first few years of problem-based learning, particularly for those who had facilitated once only. Since student and facilitator expectations in the small group tutorial may differ, roles and duties of facilitators must be explicit for both parties from the outset. PMID:14585108

What can we learn from facilitator and student perceptions of facilitation skills and roles in the first year of a problem-based learning curriculum?

PubMed

McLean, Michelle

2003-10-30

The small group tutorial is a cornerstone of problem-based learning. By implication, the role of the facilitator is of pivotal importance. The present investigation canvassed perceptions of facilitators with differing levels of experience regarding their roles and duties in the tutorial. In January 2002, one year after problem-based learning implementation at the Nelson R. Mandela School of Medicine, facilitators with the following experience were canvassed: trained and about to facilitate, facilitated once only and facilitated more than one six-week theme. Student comments regarding facilitator skills were obtained from a 2001 course survey. While facilitators generally agreed that the three-day training workshop provided sufficient insight into the facilitation process, they become more comfortable with increasing experience. Many facilitators experienced difficulty not providing content expertise. Again, this improved with increasing experience. Most facilitators saw students as colleagues. They agreed that they should be role models, but were less enthusiastic about being mentors. Students were critical of facilitators who were not up to date with curriculum implementation or who appeared disinterested. While facilitator responses suggest that there was considerable intrinsic motivation, this might in fact not be the case. Even if they had facilitated on all six themes, facilitators could still be considered as novices. Faculty support is therefore critical for the first few years of problem-based learning, particularly for those who had facilitated once only. Since student and facilitator expectations in the small group tutorial may differ, roles and duties of facilitators must be explicit for both parties from the outset.

Repeated measures from FIA data facilitates analysis across spatial scales of tree growth responses to nitrogen deposition from individual trees to whole ecoregions

Treesearch

Charles H. (Hobie) Perry; Kevin J. Horn; R. Quinn Thomas; Linda H. Pardo; Erica A.H. Smithwick; Doug Baldwin; Gregory B. Lawrence; Scott W. Bailey; Sabine Braun; Christopher M. Clark; Mark Fenn; Annika Nordin; Jennifer N. Phelan; Paul G. Schaberg; Sam St. Clair; Richard Warby; Shaun Watmough; Steven S. Perakis

2015-01-01

The abundance of temporally and spatially consistent Forest Inventory and Analysis data facilitates hierarchical/multilevel analysis to investigate factors affecting tree growth, scaling from plot-level to continental scales. Herein we use FIA tree and soil inventories in conjunction with various spatial climate and soils data to estimate species-specific responses of...

Interactions between Depression and Facilitation within Neural Networks: Updating the Dual-Process Theory of Plasticity

PubMed Central

Prescott, Steven A.

1998-01-01

Repetitive stimulation often results in habituation of the elicited response. However, if the stimulus is sufficiently strong, habituation may be preceded by transient sensitization or even replaced by enduring sensitization. In 1970, Groves and Thompson formulated the dual-process theory of plasticity to explain these characteristic behavioral changes on the basis of competition between decremental plasticity (depression) and incremental plasticity (facilitation) occurring within the neural network. Data from both vertebrate and invertebrate systems are reviewed and indicate that the effects of depression and facilitation are not exclusively additive but, rather, that those processes interact in a complex manner. Serial ordering of induction of learning, in which a depressing locus precedes the modulatory system responsible for inducing facilitation, causes the facilitation to wane. The parallel and/or serial expression of depression and waning facilitation within the stimulus–response pathway culminates in the behavioral changes that characterize dual-process learning. A mathematical model is presented to formally express and extend understanding of the interactions between depression and facilitation. PMID:10489261

Disentangling beat perception from sequential learning and examining the influence of attention and musical abilities on ERP responses to rhythm.

PubMed

Bouwer, Fleur L; Werner, Carola M; Knetemann, Myrthe; Honing, Henkjan

2016-05-01

Beat perception is the ability to perceive temporal regularity in musical rhythm. When a beat is perceived, predictions about upcoming events can be generated. These predictions can influence processing of subsequent rhythmic events. However, statistical learning of the order of sounds in a sequence can also affect processing of rhythmic events and must be differentiated from beat perception. In the current study, using EEG, we examined the effects of attention and musical abilities on beat perception. To ensure we measured beat perception and not absolute perception of temporal intervals, we used alternating loud and soft tones to create a rhythm with two hierarchical metrical levels. To control for sequential learning of the order of the different sounds, we used temporally regular (isochronous) and jittered rhythmic sequences. The order of sounds was identical in both conditions, but only the regular condition allowed for the perception of a beat. Unexpected intensity decrements were introduced on the beat and offbeat. In the regular condition, both beat perception and sequential learning were expected to enhance detection of these deviants on the beat. In the jittered condition, only sequential learning was expected to affect processing of the deviants. ERP responses to deviants were larger on the beat than offbeat in both conditions. Importantly, this difference was larger in the regular condition than in the jittered condition, suggesting that beat perception influenced responses to rhythmic events in addition to sequential learning. The influence of beat perception was present both with and without attention directed at the rhythm. Moreover, beat perception as measured with ERPs correlated with musical abilities, but only when attention was directed at the stimuli. Our study shows that beat perception is possible when attention is not directed at a rhythm. In addition, our results suggest that attention may mediate the influence of musical abilities on beat

The choice of facilitators in medical tourism.

PubMed

Gan, Lydia L; Frederick, James R

2018-01-01

The study identified which of the four facilitators (themselves, agents, insurers, or doctors) consumers are most likely to use when they travel for various medical procedures. A survey conducted between 2011 and 2014 yielded 964 responses. The multinomial logistic regression results showed that being 51-64 years old was positively related to going on their own or using agents to arrange for knee replacements. Having a high school education or less was positively linked to using both agents and insurers to facilitate knee replacements, whereas having a bachelor's degree was negatively associated with going on their own for stem cell therapy.

Community Environmental Response Facilitation Act (CERFA) report, Alabama Army Ammunition Plant, Talladega County, Alabama. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, B.; Frye, C.

1994-04-01

This report presents the results of the Community Environmental Response Facilitation Act (CERFA) investigation conducted by The Earth Technology Corporation (TETC) at Alabama Army Ammunition Plant, a U.S. Government property selected for closure by the Base Realignment and Closure (BRAC) Commission. Under CERFA, Federal agencies are required to identify real property that can be immediately reused and redeveloped. Satisfying this objective requires the identification of real property where no hazardous substances or petroleum, products, regulated by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), were stored for one year or more, known to have been released, or disposed. Themore » Alabama Army Ammunition Plant is a 2,187-acre site (more or less) located in Talladega County, Alabama, approximately 5 miles north of Childersburg, Alabama. The installation's primary mission was to manufacture explosives. Activities associated with the property that have environmental significance are the former manufacturing of explosives, the recycling of spent acids, and the disposal of wastes resulting from these operations. The facility is on U.S. Environmental Protection Agency's National Priorities List. Alabama Army Ammunition Plant, CERFA, Base closure, BRAC.« less

The Race that Precedes Coactivation: Development of Multisensory Facilitation in Children

ERIC Educational Resources Information Center

Barutchu, Ayla; Crewther, David P.; Crewther, Sheila G.

2009-01-01

Rationale: The facilitating effect of multisensory integration on motor responses in adults is much larger than predicted by race-models and is in accordance with the idea of coactivation. However, the development of multisensory facilitation of endogenously driven motor processes and its relationship to the development of complex cognitive skills…

Evolution of local facilitation in arid ecosystems.

PubMed

Kéfi, Sonia; van Baalen, Minus; Rietkerk, Max; Loreau, Michel

2008-07-01

In harsh environments, sessile organisms can make their habitat more hospitable by buffering environmental stress or increasing resource availability. Although the ecological significance of such local facilitation is widely established, the evolutionary aspects have been seldom investigated. Yet addressing the evolutionary aspects of local facilitation is important because theoretical studies show that systems with such positive interactions can exhibit alternative stable states and that such systems may suddenly become extinct when they evolve (evolutionary suicide). Arid ecosystems currently experience strong changes in climate and human pressures, but little is known about the effects of these changes on the selective pressures exerted on the vegetation. Here, we focus on the evolution of local facilitation in arid ecosystems, using a lattice-structured model explicitly considering local interactions among plants. We found that the evolution of local facilitation depends on the seed dispersal strategy. In systems characterized by short-distance seed dispersal, adaptation to a more stressful environment leads to high local facilitation, allowing the population to escape extinction. In contrast, systems characterized by long-distance seed dispersal become extinct under increased stress even when allowed to adapt. In this case, adaptation in response to climate change and human pressures could give the final push to the desertification of arid ecosystems.

Barriers and facilitators to being physically active on a rural U.S. Northern Plains American Indian reservation.

PubMed

Jahns, Lisa; McDonald, Leander R; Wadsworth, Ann; Morin, Charles; Liu, Yan

2014-11-21

The objective of the present study was to identify barriers to and facilitators of physical activity among American Indian adults living on a rural, U.S. Northern Plains reservation using the nominal group technique (NGT). NGT is a method of data generation and interpretation that combines aspects of qualitative (free generation of responses) and quantitative (systematic ranking of responses) methodologies. Adults participated in one of two NGT sessions asking about either barriers to (n = 6), or facilitators of (n = 5), being physically active. Participants nominated and ranked 21 barriers and 18 facilitators. Barriers indicated lack of knowledge of how to fit physical activity into a daily schedule, work, caring for family members, and prioritizing sedentary pursuits. Other responses included environmental barriers such as lack of access and transportation to a gym, unsafe walking conditions, and inclement weather. Facilitators to following recommendations included knowledge of health benefits of physical activity and the perception of physical activity as enjoyable, including feeling good when working out. Environmental facilitators included being outdoors walking and biking as well as parks and exercise facilities. Responses provided direction for locally designed community-based programs to promote facilitators and decrease barriers to individual's engagement in physical activity.

Text messaging to support off-campus clinical nursing facilitators: a descriptive survey.

PubMed

Howard, Christine; Fox, Amanda R; Coyer, Fiona

2014-06-01

Managing large student cohorts can be a challenge for university academics, coordinating these units. Bachelor of Nursing programmes have the added challenge of managing multiple groups of students and clinical facilitators whilst completing clinical placement. Clear, time efficient and effective communication between coordinating academics and clinical facilitators is needed to ensure consistency between student and teaching groups and prompt management of emerging issues. This study used a descriptive survey to explore the use of text messaging via a mobile phone, sent from coordinating academics to off-campus clinical facilitators, as an approach to providing direction and support. The response rate was 47.8% (n=22). Correlations were found between the approachability of the coordinating academic and clinical facilitator perception that, a) the coordinating academic understood issues on clinical placement (r=0.785, p<0.001), and b) being part of the teaching team (r=0.768, p<0.001). Analysis of responses to qualitative questions revealed three themes: connection, approachability and collaboration. This study demonstrates that use of regular text messages improves communication between coordinating academics and clinical facilitators. Findings suggest improved connection, approachability and collaboration between the coordinating academic and clinical facilitation staff. Copyright © 2014 Elsevier Ltd. All rights reserved.

Facilitators and Barriers to Preparedness Partnerships: A Veterans Affairs Medical Center Perspective.

PubMed

Schmitz, Susan; Wyte-Lake, Tamar; Dobalian, Aram

2017-09-13

This study sought to understand facilitators and barriers faced by local US Department of Veterans Affairs Medical Center (VAMC) emergency managers (EMs) when collaborating with non-VA entities. Twelve EMs participated in semi-structured interviews lasting 60 to 90 minutes discussing their collaboration with non-VAMC organizations. Sections of the interview transcripts concerning facilitators and barriers to collaboration were coded and analyzed. Common themes were organized into 2 categories: (1) internal (ie, factors affecting collaboration from within VAMCs or by VA policy) and (2) external (ie, interagency or interpersonal factors). Respondents reported a range of facilitators and barriers to collaboration with community-based agencies. Internal factors facilitating collaboration included items such as leadership support. An internal barrier example included lack of clarity surrounding the VAMC's role in community disaster response. External factors noted as facilitators included a shared goal across organizations while a noted barrier was a perception that potential partners viewed a VAMC partnership with skepticism. Federal institutions are important partners for the success of community disaster preparedness and response. Understanding the barriers that VAMCs confront, as well as potential facilitators to collaboration, should enhance the development of VAMC-community partnerships and improve community health resilience. (Disaster Med Public Health Preparedness. 2017; page 1 of 6).

Pharmacists' perceptions of facilitators and barriers to lifelong learning.

PubMed

Hanson, Alan L; Bruskiewitz, Ruth H; Demuth, James E

2007-08-15

To reevaluate facilitators of and barriers to pharmacists' participation in lifelong learning previously examined in a 1990 study. A survey instrument was mailed to 274 pharmacists who volunteered to participate based on a prior random sample survey. Data based on perceptions of facilitators and barriers to lifelong learning, as well as self-perception as a lifelong learner, were analyzed and compared to a similar 1990 survey. The response rate for the survey was 88%. The top 3 facilitators and barriers to lifelong learning from the 2003 and the 1990 samples were: (1) personal desire to learn; (2) requirement to maintain professional licensure; and (3) enjoyment/relaxation provided by learning as change of pace from the "routine." The top 3 barriers were: (1) job constraints; (2) scheduling (location, distance, time) of group learning activities; and (3) family constraints (eg, spouse, children, personal). Respondents' broad self-perception as lifelong learners continued to be highly positive overall, but remained less positive relative to more specific lifelong learning skills such as the ability to identify learning objectives as well as to evaluate learning outcomes. Little has changed in the last decade relative to how pharmacists view themselves as lifelong learners, as well as what they perceive as facilitators and barriers to lifelong learning. To address factors identified as facilitators and barriers, continuing education (CE) providers should focus on pharmacists' time constraints, whether due to employment, family responsibilities, or time invested in the educational activity itself, and pharmacists' internal motivations to learn (personal desire, enjoyment), as well as external forces such as mandatory CE for relicensure.

Body Posture Facilitates Retrieval of Autobiographical Memories

ERIC Educational Resources Information Center

Dijkstra, Katinka; Kaschak, Michael P.; Zwaan, Rolf A.

2007-01-01

We assessed potential facilitation of congruent body posture on access to and retention of autobiographical memories in younger and older adults. Response times were shorter when body positions during prompted retrieval of autobiographical events were similar to the body positions in the original events than when body position was incongruent.…

Changes in root hydraulic conductivity facilitate the overall hydraulic response of rice (Oryza sativa L.) cultivars to salt and osmotic stress.

PubMed

Meng, Delong; Fricke, Wieland

2017-04-01

The aim of the present work was to assess the significance of changes in root AQP gene expression and hydraulic conductivity (Lp) in the regulation of water balance in two hydroponically-grown rice cultivars (Azucena, Bala) which differ in root morphology, stomatal regulation and aquaporin (AQP) isoform expression. Plants were exposed to NaCl (25 mM, 50 mM) and osmotic stress (5%, 10% PEG6000). Root Lp was determined for exuding root systems (osmotic forces driving water uptake; 'exudation Lp') and transpiring plants (hydrostatic forces dominating; 'transpiration-Lp'). Gene expression was analysed by qPCR. Stress treatments caused a consistent and significant decrease in plant growth, transpirational water loss, stomatal conductance, shoot-to-root surface area ratio and root Lp. Comparison of exudation-with transpiration-Lp supported a significant contribution of AQP-facilitated water flow to root water uptake. Changes in root Lp in response to treatments were correlated much stronger with root morphological characteristics, such as the number of main and lateral roots, surface area ratio of root to shoot and plant transpiration rate than with AQP gene expression. Changes in root Lp, involving AQP function, form an integral part of the plant hydraulic response to stress and facilitate changes in the root-to-shoot surface area ratio, transpiration and stomatal conductance. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Increased temporal variability of striatum region facilitating the early antidepressant response in patients with major depressive disorder.

PubMed

Hou, Zhenghua; Kong, Youyong; He, Xiaofu; Yin, Yingying; Zhang, Yuqun; Yuan, Yonggui

2018-07-13

The aim of this study is to identify the difference of temporal variability among major depressive disorder (MDD) patients (with different early antidepressant responses) and healthy controls (HC), and further explore the relationship between pre-treatment temporal variability and early antidepressant response. At baseline, 77 treatment-naïve inpatients with MDD and 42 matched HC received clinical assessments and 3.0 Tesla resting-state functional magnetic resonance imaging scans. After 2 weeks' antidepressant treatment, the patients were subgrouped into responsive depression (RD, n = 40) and non-responding depression (NRD, n = 37) based on the reduction of Hamilton depression rating scale (HAMD). The temporal variability of 90 brain nodes was calculated for further analysis. Compared with the HC group, both the RD and NRD subjects showed greater baseline temporal variability (i.e., greater dynamic) in the left inferior occipital gyrus. Significantly greater temporal variability in the left pallidum was found in the RD group than the NRD and the HC groups, and the higher variability of left pallidum correlated positively with the HAMD reduction. Moreover, the pooled MDD (i.e., RD and NRD) group showed greater baseline temporal variability in the right inferior frontal gyrus, the left inferior occipital gyrus, the bilateral fusiform gyri and the left Heschl gyrus than the HC group. The distinctive pattern of dynamically reorganized networks may provide a crucial scaffold to facilitate early antidepressant response, and the temporal variability may serve as a promising indicator for the personalized therapy of MDD. Copyright © 2018 Elsevier Inc. All rights reserved.

Rapid response to intensive treatment for bulimia nervosa and purging disorder: A randomized controlled trial of a CBT intervention to facilitate early behavior change.

PubMed

MacDonald, Danielle E; McFarlane, Traci L; Dionne, Michelle M; David, Lauren; Olmsted, Marion P

2017-09-01

Rapid response to cognitive behavior therapy (CBT) for eating disorders (i.e., rapid and substantial change to key eating disorder behaviors in the initial weeks of treatment) robustly predicts good outcome at end-of-treatment and in follow up. The objective of this study was to determine whether rapid response to day hospital (DH) eating disorder treatment could be facilitated using a brief adjunctive CBT intervention focused on early change. 44 women (average age 27.3 [8.4]; 75% White, 6.3% Black, 6.9% Asian) were randomly assigned to 1 of 2 4-session adjunctive interventions: CBT focused on early change, or motivational interviewing (MI). DH was administered as usual. Outcomes included binge/purge frequency, Eating Disorder Examination-Questionnaire and Difficulties in Emotion Regulation Scale. Intent-to-treat analyses were used. The CBT group had a higher rate of rapid response (95.7%) compared to MI (71.4%; p = .04, V = .33). Those who received CBT also had fewer binge/purge episodes (p = .02) in the first 4 weeks of DH. By end-of-DH, CBT participants made greater improvements on overvaluation of weight and shape (p = .008), and emotion regulation (ps < .008). Across conditions, there were no significant baseline differences between rapid and nonrapid responders (ps > .05). The results of this study demonstrate that rapid response can be clinically facilitated using a CBT intervention that explicitly encourages early change. This provides the foundation for future research investigating whether enhancing rates of rapid response using such an intervention results in improved longer term outcomes. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

After the strike: using facilitation in a residency training program

PubMed Central

Andres, D; Hamoline, D; Sanders, M; Anderson, J

1998-01-01

Methods of alternative dispute resolution, including facilitation, can be used to identify and resolve areas of conflict. Facilitation was used by the University of Saskatchewan's Department of Family Medicine (Saskatoon division) after the strike by residents in July and August 1995 so as to allow optimal use of the remaining educational time. Through facilitation, experiences of the strike and areas of potential conflict were explored. Participants had a broad range of responses to the strike. Specific coping strategies were developed to deal with identified concerns. Although outcomes were not measured formally, levels of trust improved and collegial relationships were restored. Because so many changes occur in health care and medical education, conflict inevitably arises. Facilitation offers one way of dealing with change constructively, thereby making possible the optimal use of educational time. PMID:9526479

After the strike: using facilitation in a residency training program.

PubMed

Andres, D; Hamoline, D; Sanders, M; Anderson, J

1998-03-10

Methods of alternative dispute resolution, including facilitation, can be used to identify and resolve areas of conflict. Facilitation was used by the University of Saskatchewan's Department of Family Medicine (Saskatoon division) after the strike by residents in July and August 1995 so as to allow optimal use of the remaining educational time. Through facilitation, experiences of the strike and areas of potential conflict were explored. Participants had a broad range of responses to the strike. Specific coping strategies were developed to deal with identified concerns. Although outcomes were not measured formally, levels of trust improved and collegial relationships were restored. Because so many changes occur in health care and medical education, conflict inevitably arises. Facilitation offers one way of dealing with change constructively, thereby making possible the optimal use of educational time.

Practice Facilitators' and Leaders' Perspectives on a Facilitated Quality Improvement Program.

PubMed

McHugh, Megan; Brown, Tiffany; Liss, David T; Walunas, Theresa L; Persell, Stephen D

2018-04-01

Practice facilitation is a promising approach to helping practices implement quality improvements. Our purpose was to describe practice facilitators' and practice leaders' perspectives on implementation of a practice facilitator-supported quality improvement program and describe where their perspectives aligned and diverged. We conducted interviews with practice leaders and practice facilitators who participated in a program that included 35 improvement strategies aimed at the ABCS of heart health (aspirin use in high-risk individuals, blood pressure control, cholesterol management, and smoking cessation). Rapid qualitative analysis was used to collect, organize, and analyze the data. We interviewed 17 of the 33 eligible practice leaders, and the 10 practice facilitators assigned to those practices. Practice leaders and practice facilitators both reported value in the program's ability to bring needed, high-quality resources to practices. Practice leaders appreciated being able to set the schedule for facilitation and select among the 35 interventions. According to practice facilitators, however, relying on practice leaders to set the pace of the intervention resulted in a lower level of program intensity than intended. Practice leaders preferred targeted assistance, particularly electronic health record documentation guidance and linkages to state smoking cessation programs. Practice facilitators reported that the easiest interventions were those that did not alter care practices. The dual perspectives of practice leaders and practice facilitators provide a more holistic picture of enablers and barriers to program implementation. There may be greater opportunities to assist small practices through simple, targeted practice facilitator-supported efforts rather than larger, comprehensive quality improvement projects. © 2018 Annals of Family Medicine, Inc.

Barriers and Facilitators to Being Physically Active on a Rural U.S. Northern Plains American Indian Reservation

PubMed Central

Jahns, Lisa; McDonald, Leander R.; Wadsworth, Ann; Morin, Charles; Liu, Yan

2014-01-01

The objective of the present study was to identify barriers to and facilitators of physical activity among American Indian adults living on a rural, U.S. Northern Plains reservation using the nominal group technique (NGT). NGT is a method of data generation and interpretation that combines aspects of qualitative (free generation of responses) and quantitative (systematic ranking of responses) methodologies. Adults participated in one of two NGT sessions asking about either barriers to (n = 6), or facilitators of (n = 5), being physically active. Participants nominated and ranked 21 barriers and 18 facilitators. Barriers indicated lack of knowledge of how to fit physical activity into a daily schedule, work, caring for family members, and prioritizing sedentary pursuits. Other responses included environmental barriers such as lack of access and transportation to a gym, unsafe walking conditions, and inclement weather. Facilitators to following recommendations included knowledge of health benefits of physical activity and the perception of physical activity as enjoyable, including feeling good when working out. Environmental facilitators included being outdoors walking and biking as well as parks and exercise facilities. Responses provided direction for locally designed community-based programs to promote facilitators and decrease barriers to individual’s engagement in physical activity. PMID:25421064

Transformative learning theory: facilitating mammography screening in rural women.

PubMed

Purtzer, Mary Anne; Overstreet, Lindsey

2014-03-01

To use transformative learning to investigate what experiences serve as catalysts for mammography screening, the cognitive and affective responses that result from the catalyst, and how screening behavior is impacted. A descriptive qualitative study. Southeastern Wyoming. 25 low-income, rural women aged 40 years and older. Four focus group interviews. Cancer experiences triggered universal responses of fear by screeners and nonscreeners. The manner in which that fear response was interpreted was a critical factor in the facilitation of, or impedance to, screening. Dichotomous interpretations of fear responses provided the context for screening behavior. Immobilizing and isolating experiences were associated with nonscreening behavior, whereas motivation and self-efficacy were associated with screening behavior. Transformative learning theory is a useful framework from which to explain differences in mammography screening behavior. Creating opportunities that facilitate dialogue and critical reflection hold the potential to change immobilizing and isolating frames of reference in nonscreening women. To help women transcend their fear and become self-efficacious, nurses can assess how cancer and the screening experience is viewed and, if indicated, move beyond standard education and offer opportunities for dialogue and critical reflection.

Pharmacists' Perceptions of Facilitators and Barriers to Lifelong Learning

PubMed Central

Bruskiewitz, Ruth H.; DeMuth, James E.

2007-01-01

Objectives To reevaluate facilitators of and barriers to pharmacists' participation in lifelong learning previously examined in a 1990 study. Methods A survey instrument was mailed to 274 pharmacists who volunteered to participate based on a prior random sample survey. Data based on perceptions of facilitators and barriers to lifelong learning, as well as self-perception as a lifelong learner, were analyzed and compared to a similar 1990 survey. Results The response rate for the survey was 88%. The top 3 facilitators and barriers to lifelong learning from the 2003 and the 1990 samples were: (1) personal desire to learn; (2) requirement to maintain professional licensure; and (3) enjoyment/relaxation provided by learning as change of pace from the “routine.” The top 3 barriers were: (1) job constraints; (2) scheduling (location, distance, time) of group learning activities; and (3) family constraints (eg, spouse, children, personal). Respondents' broad self-perception as lifelong learners continued to be highly positive overall, but remained less positive relative to more specific lifelong learning skills such as the ability to identify learning objectives as well as to evaluate learning outcomes. Conclusions Little has changed in the last decade relative to how pharmacists view themselves as lifelong learners, as well as what they perceive as facilitators and barriers to lifelong learning. To address factors identified as facilitators and barriers, continuing education (CE) providers should focus on pharmacists' time constraints, whether due to employment, family responsibilities, or time invested in the educational activity itself, and pharmacists' internal motivations to learn (personal desire, enjoyment), as well as external forces such as mandatory CE for relicensure. PMID:17786254

Human CST Facilitates Genome-wide RAD51 Recruitment to GC-Rich Repetitive Sequences in Response to Replication Stress.

PubMed

Chastain, Megan; Zhou, Qing; Shiva, Olga; Fadri-Moskwik, Maria; Whitmore, Leanne; Jia, Pingping; Dai, Xueyu; Huang, Chenhui; Ye, Ping; Chai, Weihang

2016-08-02

The telomeric CTC1/STN1/TEN1 (CST) complex has been implicated in promoting replication recovery under replication stress at genomic regions, yet its precise role is unclear. Here, we report that STN1 is enriched at GC-rich repetitive sequences genome-wide in response to hydroxyurea (HU)-induced replication stress. STN1 deficiency exacerbates the fragility of these sequences under replication stress, resulting in chromosome fragmentation. We find that upon fork stalling, CST proteins form distinct nuclear foci that colocalize with RAD51. Furthermore, replication stress induces physical association of CST with RAD51 in an ATR-dependent manner. Strikingly, CST deficiency diminishes HU-induced RAD51 foci formation and reduces RAD51 recruitment to telomeres and non-telomeric GC-rich fragile sequences. Collectively, our findings establish that CST promotes RAD51 recruitment to GC-rich repetitive sequences in response to replication stress to facilitate replication restart, thereby providing insights into the mechanism underlying genome stability maintenance. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Response properties of the refractory auditory nerve fiber.

PubMed

Miller, C A; Abbas, P J; Robinson, B K

2001-09-01

The refractory characteristics of auditory nerve fibers limit their ability to accurately encode temporal information. Therefore, they are relevant to the design of cochlear prostheses. It is also possible that the refractory property could be exploited by prosthetic devices to improve information transfer, as refractoriness may enhance the nerve's stochastic properties. Furthermore, refractory data are needed for the development of accurate computational models of auditory nerve fibers. We applied a two-pulse forward-masking paradigm to a feline model of the human auditory nerve to assess refractory properties of single fibers. Each fiber was driven to refractoriness by a single (masker) current pulse delivered intracochlearly. Properties of firing efficiency, latency, jitter, spike amplitude, and relative spread (a measure of dynamic range and stochasticity) were examined by exciting fibers with a second (probe) pulse and systematically varying the masker-probe interval (MPI). Responses to monophasic cathodic current pulses were analyzed. We estimated the mean absolute refractory period to be about 330 micros and the mean recovery time constant to be about 410 micros. A significant proportion of fibers (13 of 34) responded to the probe pulse with MPIs as short as 500 micros. Spike amplitude decreased with decreasing MPI, a finding relevant to the development of computational nerve-fiber models, interpretation of gross evoked potentials, and models of more central neural processing. A small mean decrement in spike jitter was noted at small MPI values. Some trends (such as spike latency-vs-MPI) varied across fibers, suggesting that sites of excitation varied across fibers. Relative spread was found to increase with decreasing MPI values, providing direct evidence that stochastic properties of fibers are altered under conditions of refractoriness.

Pointing control for LDR

NASA Technical Reports Server (NTRS)

Yam, Y.; Briggs, C.

1988-01-01

One important aspect of the LDR control problem is the possible excitations of structural modes due to random disturbances, mirror chopping, and slewing maneuvers. An analysis was performed to yield a first order estimate of the effects of such dynamic excitations. The analysis involved a study of slewing jitters, chopping jitters, disturbance responses, and pointing errors, making use of a simplified planar LDR model which describes the LDR dynamics on a plane perpendicular to the primary reflector. Briefly, the results indicate that the command slewing profile plays an important role in minimizing the resultant jitter, even to a level acceptable without any control action. An optimal profile should therefore be studied.

Neural spike-timing patterns vary with sound shape and periodicity in three auditory cortical fields

PubMed Central

Lee, Christopher M.; Osman, Ahmad F.; Volgushev, Maxim; Escabí, Monty A.

2016-01-01

Mammals perceive a wide range of temporal cues in natural sounds, and the auditory cortex is essential for their detection and discrimination. The rat primary (A1), ventral (VAF), and caudal suprarhinal (cSRAF) auditory cortical fields have separate thalamocortical pathways that may support unique temporal cue sensitivities. To explore this, we record responses of single neurons in the three fields to variations in envelope shape and modulation frequency of periodic noise sequences. Spike rate, relative synchrony, and first-spike latency metrics have previously been used to quantify neural sensitivities to temporal sound cues; however, such metrics do not measure absolute spike timing of sustained responses to sound shape. To address this, in this study we quantify two forms of spike-timing precision, jitter, and reliability. In all three fields, we find that jitter decreases logarithmically with increase in the basis spline (B-spline) cutoff frequency used to shape the sound envelope. In contrast, reliability decreases logarithmically with increase in sound envelope modulation frequency. In A1, jitter and reliability vary independently, whereas in ventral cortical fields, jitter and reliability covary. Jitter time scales increase (A1 < VAF < cSRAF) and modulation frequency upper cutoffs decrease (A1 > VAF > cSRAF) with ventral progression from A1. These results suggest a transition from independent encoding of shape and periodicity sound cues on short time scales in A1 to a joint encoding of these same cues on longer time scales in ventral nonprimary cortices. PMID:26843599

Pineapple bromelain induces autophagy, facilitating apoptotic response in mammary carcinoma cells.

PubMed

Bhui, Kulpreet; Tyagi, Shilpa; Prakash, Bharti; Shukla, Yogeshwer

2010-01-01

Bromelain, from pineapple, possesses potent anticancer effects. We investigated autophagic phenomenon in mammary carcinoma cells (estrogen receptor positive and negative) under bromelain treatment and also illustrated the relationship between autophagy and apoptosis in MCF-7 cells. MCF-7 cells exposed to bromelain showed delayed growth inhibitory response and induction of autophagy, identified by monodansylcadaverine localization. It was succeeded by apoptotic cell death, evident by sub-G1 cell fraction and apoptotic features like chromatin condensation and nuclear cleavage. 3-Methyladenine (MA, autophagy inhibitor) pretreatment reduced the bromelain-induced autophagic level, also leading to decline in apoptotic population, indicating that here autophagy facilitates apoptosis. However, addition of caspase-9 inhibitor Z-LEHD-FMK augmented the autophagy levels, inhibited morphological apoptosis but did not prevent cell death. Next, we found that bromelain downregulated the phosphorylation of extracellular signal-regulated kinase ½ (ERK½), whereas that of c-jun N-terminal kinase (JNK) and p38 kinase were upregulated. Also, MA had no influence on bromelain-suppressed ERK½ activation, yet, it downregulated JNK and p38 activation. Also, addition of mitogen-activated protein kinase (MAPK) inhibitors enhanced the autophagic ratios, which suggested the role of MAP kinases in bromelain-induced autophagy. All three MAPKs were seen to be constantly activated over the time. Bromelain was seen to induce the expressions of autophagy-related proteins, light chain 3 protein B II (LC3BII), and beclin-1. Using ERK½ inhibitor, expressions of LC3BII and beclin-1 increased, whereas p38 and JNK inhibitors decreased this protein expression, indicating that bromelain-induced autophagy was positively regulated by p38 and JNK but negatively regulated by ERK½. Autophagy-inducing property of bromelain can be further exploited in breast cancer therapy. Copyright © 2010 International Union

The Influence of Facilitator and Facilitation Characteristics on Participants' Ratings of Stepfamily Education

ERIC Educational Resources Information Center

Higginbotham, Brian J.; Myler, Cory

2010-01-01

We examine the relative importance of facilitator and facilitation characteristics on participant ratings of a stepfamily education program. Data from 48 facilitators and 598 participants suggest that quality facilitation is more meaningful to participants than whether facilitators have comparable demographic characteristics or life experiences.…

Questioning skills of clinical facilitators supporting undergraduate nursing students.

PubMed

Phillips, Nicole M; Duke, Maxine M; Weerasuriya, Rona

2017-12-01

To report on a study investigating questioning skills of clinical facilitators who support the learning of undergraduate nursing students. The ability to think critically is integral to decision-making and the provision of safe and quality patient care. Developing students' critical thinking skills is expected of those who supervise and facilitate student learning in the clinical setting. Models used to facilitate student learning in the clinical setting have changed over the years with clinicians having dual responsibility for patient care and facilitating student learning. Many of these nurses have no preparation for the educative role. This study adapted a comparative study conducted over fifteen years ago. Descriptive online survey including three acute care patient scenarios involving an undergraduate nursing student. Participants were required to identify the questions they would ask the student in relation to the scenario. A total of 133 clinical facilitators including clinical teachers, clinical educators and preceptors from five large partner healthcare organisations of one Australian university participated. The majority of questions asked were knowledge questions, the lowest category in the cognitive domain requiring only simple recall of information. Facilitators who had undertaken an education-related course/workshop or formal qualification asked significantly more questions from the higher cognitive level. The study provides some evidence that nursing facilitators in the clinical setting ask students predominantly low-level questions. Further research is needed to identify strategies that develop the capacity of facilitators to ask higher level cognitive questions. Clinical facilitators should undertake targeted education that focuses on how to frame questions for students that demand application, analysis, synthesis and evaluation. © 2017 John Wiley & Sons Ltd.

School Administrator Perceptions of Cyberbullying Facilitators and Barriers to Preventive Action: A Qualitative Study.

PubMed

Young, Rachel; Tully, Melissa; Ramirez, Marizen

2017-06-01

Schools are often held responsible for preventing or addressing cyberbullying, yet little is known about school administrator perceptions of cyberbullying and the challenges they face in addressing this public health issue. The goal of this study is to examine school administrators' perceptions of the facilitators of cyberbullying and barriers to primary and secondary prevention strategies. Public school administrators ( N = 36) participated in in-depth interviews about bullying and discussed their experiences with cyberbullying and their perceptions of cyberbullying facilitators and barriers to prevention. Three main themes arose from the analysis: (1) cyberbullying as a major challenge; (2) facilitators of cyberbullying and barriers to preventive action, including parents and technology; and (3) prevention efforts, including unclear jurisdiction for action, primary versus secondary prevention efforts, and technology attributes that facilitate school response to bullying. Although administrators perceive cyberbullying as a major challenge facing their schools, they are often unsure about appropriate primary and secondary prevention efforts. Relationships with parents and police complicate response and prevention as schools attempt to navigate unclear jurisdiction. Additionally, technology presents a challenge to schools because it is seen as an enabler of cyberbullying, a facilitator of prevention, and a necessary part of education efforts. Lack of research on prevention strategies, parents' knowledge and attitudes, and confusion about responsibility for addressing cyberbullying are barriers to action. Findings suggest administrators could benefit from additional clarity on which strategies are most effective for primary prevention of cyberbullying, and that prevention strategies should proactively involve parents to promote effective collaboration with schools.

Facilitation of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor transmission in the suprachiasmatic nucleus by aniracetam enhances photic responses of the biological clock in rodents.

PubMed

Moriya, Takahiro; Ikeda, Masayuki; Teshima, Koji; Hara, Reiko; Kuriyama, Koji; Yoshioka, Tohru; Allen, Charles N; Shibata, Shigenobu

2003-05-01

This study was designed to test whether the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor-facilitating drug, aniracetam, could potentiate photic responses of the biological clock in the suprachiasmatic nucleus (SCN) of rodents. Using the whole-cell patch technique, we first demonstrated that AMPA currents elicited by either local AMPA application or optic chiasm stimulation were augmented by aniracetam in the neurons of the SCN. The AMPA application-elicited increase of intracellular Ca2+ concentration in SCN slices was also enhanced by aniracetam treatment. The systemic injection of aniracetam dose-dependently (10-100 mg/kg) potentiated the phase delay in behavioral rhythm induced by brief light exposure of low intensity (3 lux) but not high intensity (10 or 60 lux) during early subjective night. Under the blockade of NMDA receptors by (+) MK801, aniracetam failed to potentiate a light (3 lux)-induced phase delay in behavioral rhythm. Aniracetam increased the photic induction of c-Fos protein in the SCN that was elicited by low intensity light exposure (3 lux). These results suggest that AMPA receptor-mediated responses facilitated by aniracetam can explain enhanced photic responses of the biological clock in the SCN of rodents.

Facilitation of the flexor reflex in the cat by intrathecal injection of catecholamines

PubMed Central

Dhawan, B. N.; Sharma, J. N.

1970-01-01

1. Effects of some α- and β-adrenoceptor stimulants and antagonists were investigated on flexor reflex (FR) in chloralosed cats. 2. Noradrenaline (NA) produced facilitation of FR which was dose-dependent and reproducible and was blocked by α-adrenoceptor blocking agents. 3. Strychnine also produced facilitation of FR but the response was unaffected by α-adrenoceptor blocking agents. 4. Metaraminol and α-methyl-noradrenaline had little effect on FR but blocked the NA response. 5. β-adrenoceptor stimulants and antagonists had neither any effect on FR nor modified the NA response. 6. Vasopressin and histamine also failed to modify FR. 7. Possibility of α-adrenoceptors in the neurones integrating FR is suggested. PMID:4395376

Using learning theory, interprofessional facilitation competencies, and behavioral indicators to evaluate facilitator training.

PubMed

LeGros, Theresa A; Amerongen, Helen M; Cooley, Janet H; Schloss, Ernest P

2015-01-01

Despite the increasing need for faculty and preceptors skilled in interprofessional facilitation (IPF), the relative novelty of the field poses a challenge to the development and evaluation of IPF programs. We use learning theory and IPF competencies with associated behavioral indicators to develop and evaluate six key messages in IPF training and experience. Our mixed methods approach included two phases: quantitative data collection with embedded qualitative data, followed by qualitative data collection in explanatory sequential fashion. This enabled triangulated analyses of both data types and of facilitation behaviors from facilitator and student perspectives. Results indicate the competency-based training was effective. Facilitators felt comfortable performing behaviors associated with IPF competencies; student observations of those behaviors supported facilitator self-reported performance. Overall, students perceived more facilitation opportunities than facilitators. Findings corroborate the importance of recruiting seasoned facilitators and establishing IPF guidelines that acknowledge variable team dynamics and help facilitators recognize teachable moments.

Post-Exposure Sleep Deprivation Facilitates Correctly Timed Interactions Between Glucocorticoid and Adrenergic Systems, which Attenuate Traumatic Stress Responses

PubMed Central

Cohen, Shlomi; Kozlovsky, Nitsan; Matar, Michael A; Kaplan, Zeev; Zohar, Joseph; Cohen, Hagit

2012-01-01

Reliable evidence supports the role of sleep in learning and memory processes. In rodents, sleep deprivation (SD) negatively affects consolidation of hippocampus-dependent memories. As memory is integral to post-traumatic stress symptoms, the effects of post-exposure SD on various aspect of the response to stress in a controlled, prospective animal model of post-traumatic stress disorder (PTSD) were evaluated. Rats were deprived of sleep for 6 h throughout the first resting phase after predator scent stress exposure. Behaviors in the elevated plus-maze and acoustic startle response tests were assessed 7 days later, and served for classification into behavioral response groups. Freezing response to a trauma reminder was assessed on day 8. Urine samples were collected daily for corticosterone levels, and heart rate (HR) was also measured. Finally, the impact of manipulating the hypothalamus–pituitary–adrenal axis and adrenergic activity before SD was assessed. Mifepristone (MIFE) and epinephrine (EPI) were administered systemically 10-min post-stress exposure and behavioral responses and response to trauma reminder were measured on days 7–8. Hippocampal expression of glucocorticoid receptors (GRs) and morphological assessment of arborization and dendritic spines were subsequently evaluated. Post-exposure SD effectively ameliorated long-term, stress-induced, PTSD-like behavioral disruptions, reduced trauma reminder freezing responses, and decreased hippocampal expression of GR compared with exposed-untreated controls. Although urine corticosterone levels were significantly elevated 1 h after SD and the HR was attenuated, antagonizing GRs with MIFE or stimulation of adrenergic activity with EPI effectively abolished the effect of SD. MIFE- and EPI-treated animals clearly demonstrated significantly lower total dendritic length, fewer branches and lower spine density along dentate gyrus dendrites with increased levels of GR expression 8 days after exposure, as

Adapted cuing technique: facilitating sequential phoneme production.

PubMed

Klick, S L

1994-09-01

ACT is a visual cuing technique designed to facilitate dyspraxic speech by highlighting the sequential production of phonemes. In using ACT, cues are presented in such a way as to suggest sequential, coarticulatory movement in an overall pattern of motion. While using ACT, the facilitator's hand moves forward and back along the side of her (or his) own face. Finger movements signal specific speech sounds in formations loosely based on the manual alphabet for the hearing impaired. The best movements suggest the flowing, interactive nature of coarticulated phonemes. The synergistic nature of speech is suggested by coordinated hand motions which tighten and relax, move quickly or slowly, reflecting the motions of the vocal tract at various points during production of phonemic sequences. General principles involved in using ACT include a primary focus on speech-in-motion, the monitoring and fading of cues, and the presentation of stimuli based on motor-task analysis of phonemic sequences. Phonemic sequences are cued along three dimensions: place, manner, and vowel-related mandibular motion. Cuing vowels is a central feature of ACT. Two parameters of vowel production, focal point of resonance and mandibular closure, are cued. The facilitator's hand motions reflect the changing shape of the vocal tract and the trajectory of the tongue that result from the coarticulation of vowels and consonants. Rigid presentation of the phonemes is secondary to the facilitator's primary focus on presenting the overall sequential movement. The facilitator's goal is to self-tailor ACT in response to the changing needs and abilities of the client.(ABSTRACT TRUNCATED AT 250 WORDS)

PLATSIM: A Simulation and Analysis Package for Large-Order Flexible Systems. Version 2.0

NASA Technical Reports Server (NTRS)

Maghami, Peiman G.; Kenny, Sean P.; Giesy, Daniel P.

1997-01-01

The software package PLATSIM provides efficient time and frequency domain analysis of large-order generic space platforms. PLATSIM can perform open-loop analysis or closed-loop analysis with linear or nonlinear control system models. PLATSIM exploits the particular form of sparsity of the plant matrices for very efficient linear and nonlinear time domain analysis, as well as frequency domain analysis. A new, original algorithm for the efficient computation of open-loop and closed-loop frequency response functions for large-order systems has been developed and is implemented within the package. Furthermore, a novel and efficient jitter analysis routine which determines jitter and stability values from time simulations in a very efficient manner has been developed and is incorporated in the PLATSIM package. In the time domain analysis, PLATSIM simulates the response of the space platform to disturbances and calculates the jitter and stability values from the response time histories. In the frequency domain analysis, PLATSIM calculates frequency response function matrices and provides the corresponding Bode plots. The PLATSIM software package is written in MATLAB script language. A graphical user interface is developed in the package to provide convenient access to its various features.

Comparison of Oculus Rift and HTC Vive: Feasibility for Virtual Reality-Based Exploration, Navigation, Exergaming, and Rehabilitation.

PubMed

Borrego, Adrián; Latorre, Jorge; Alcañiz, Mariano; Llorens, Roberto

2018-06-01

The latest generation of head-mounted displays (HMDs) provides built-in head tracking, which enables estimating position in a room-size setting. This feature allows users to explore, navigate, and move within real-size virtual environments, such as kitchens, supermarket aisles, or streets. Previously, these actions were commonly facilitated by external peripherals and interaction metaphors. The objective of this study was to compare the Oculus Rift and the HTC Vive in terms of the working range of the head tracking and the working area, accuracy, and jitter in a room-size environment, and to determine their feasibility for serious games, rehabilitation, and health-related applications. The position of the HMDs was registered in a 10 × 10 grid covering an area of 25 m 2 at sitting (1.3 m) and standing (1.7 m) heights. Accuracy and jitter were estimated from positional data. The working range was estimated by moving the HMDs away from the cameras until no data were obtained. The HTC Vive provided a working area (24.87 m 2 ) twice as large as that of the Oculus Rift. Both devices showed excellent and comparable performance at sitting height (accuracy up to 1 cm and jitter <0.35 mm), and the HTC Vive presented worse but still excellent accuracy and jitter at standing height (accuracy up to 1.5 cm and jitter <0.5 mm). The HTC Vive presented a larger working range (7 m) than did the Oculus Rift (4.25 m). Our results support the use of these devices for real navigation, exploration, exergaming, and motor rehabilitation in virtual reality environments.

Physical activity barriers and facilitators among working mothers and fathers.

PubMed

Mailey, Emily L; Huberty, Jennifer; Dinkel, Danae; McAuley, Edward

2014-06-27

The transition to parenthood is consistently associated with declines in physical activity. In particular, working parents are at risk for inactivity, but research exploring physical activity barriers and facilitators in this population has been scarce. The purpose of this study was to qualitatively examine perceptions of physical activity among working parents. Working mothers (n = 13) and fathers (n = 12) were recruited to participate in one of four focus group sessions and discuss physical activity barriers and facilitators. Data were analyzed using immersion/crystallization in NVivo 10. Major themes for barriers included family responsibilities, guilt, lack of support, scheduling constraints, and work. Major themes for facilitators included being active with children or during children's activities, being a role model for children, making time/prioritizing, benefits to health and family, and having support available. Several gender differences emerged within each theme, but overall both mothers and fathers reported their priorities had shifted to focus on family after becoming parents, and those who were fitting in physical activity had developed strategies that allowed them to balance their household and occupational responsibilities. The results of this study suggest working mothers and fathers report similar physical activity barriers and facilitators and would benefit from interventions that teach strategies for overcoming barriers and prioritizing physical activity amidst the demands of parenthood. Future interventions might consider targeting mothers and fathers in tandem to create an optimally supportive environment in the home.

Physical activity barriers and facilitators among working mothers and fathers

PubMed Central

2014-01-01

Background The transition to parenthood is consistently associated with declines in physical activity. In particular, working parents are at risk for inactivity, but research exploring physical activity barriers and facilitators in this population has been scarce. The purpose of this study was to qualitatively examine perceptions of physical activity among working parents. Methods Working mothers (n = 13) and fathers (n = 12) were recruited to participate in one of four focus group sessions and discuss physical activity barriers and facilitators. Data were analyzed using immersion/crystallization in NVivo 10. Results Major themes for barriers included family responsibilities, guilt, lack of support, scheduling constraints, and work. Major themes for facilitators included being active with children or during children’s activities, being a role model for children, making time/prioritizing, benefits to health and family, and having support available. Several gender differences emerged within each theme, but overall both mothers and fathers reported their priorities had shifted to focus on family after becoming parents, and those who were fitting in physical activity had developed strategies that allowed them to balance their household and occupational responsibilities. Conclusions The results of this study suggest working mothers and fathers report similar physical activity barriers and facilitators and would benefit from interventions that teach strategies for overcoming barriers and prioritizing physical activity amidst the demands of parenthood. Future interventions might consider targeting mothers and fathers in tandem to create an optimally supportive environment in the home. PMID:24974148

Stress-induced facilitation of host response to bacterial challenge in F344 rats is dependent on extracellular heat shock protein 72 and independent of alpha beta T cells.

PubMed

Campisi, Jay; Sharkey, Craig; Johnson, John D; Asea, Alexzander; Maslanik, Thomas; Bernstein-Hanley, Isaac; Fleshner, Monika

2012-11-01

Activation of the in vivo stress response can facilitate antibacterial host defenses. One possible mechanism for this effect is stress-induced release of heat shock protein 72 (Hsp72) into the extracellular environment. Hsp72 is a ubiquitous cellular protein that is up-regulated in response to cellular stress, and modulates various aspects of immune function including macrophage inflammatory/bactericidal responses and T-cell function when found in the extracellular environment. The current study tested the hypothesis that in vivo extracellular Hsp72 (eHsp72) at the site of inflammation contributes to stress-induced restricted development of bacteria, and facilitated recovery from bacteria-induced inflammation, and that this effect is independent of alpha beta (αβ) T cells. Male F344 rats were exposed to either inescapable electrical tail-shocks or no stress, and subcutaneously injected with Escherichia coli (ATCC 15746). The role of eHsp72 was investigated by Hsp72-immunoneutralization at the inflammatory site. The potential contribution of T cells was examined by testing male athymic (rnu/rnu) nude rats lacking mature αβ T cells and heterozygous thymic intact control (rnu/+) rats. The results were that stressor exposure increased plasma concentrations of eHsp72 and facilitated recovery from bacterial inflammation. Immunoneutralization of eHsp72 at the inflammatory site attenuated this effect. Stressor exposure impacted bacterial inflammation and eHsp72 equally in both athymic and intact control rats. These results support the hypothesis that eHsp72 at the site of inflammation, and not αβ T cells, contributes to the effect of stressor exposure on subcutaneous bacterial inflammation.

Language and the Facilitation of Authority: The Discourse of Noam Chomsky (Reader Response).

ERIC Educational Resources Information Center

Beaugrande, Robert de

1991-01-01

Applies discourse analysis to an interview with Noam Chomsky to show the use of language to facilitate authority. Discusses idealism and scientism, change and the role of the intellectual, Chomsky's dualism, his "problem," his method, creativity and composition, activism and the intellectual, and the future of intellectualism. (PRA)

Barriers and Facilitators to Integrating Health Service Responses to Intimate Partner Violence in Low‐ and Middle‐Income Countries: A Comparative Health Systems and Service Analysis

PubMed Central

Colombini, Manuela; Dockerty, Colleen; Mayhew, Susannah H.

2017-01-01

This systematic review synthesizes 11 studies of health‐sector responses to intimate partner violence (IPV) in low‐ and middle‐income countries. The services that were most comprehensive and integrated in their responsiveness to IPV were primarily in primary health and antenatal care settings. Findings suggest that the following facilitators are important: availability of clear guidelines, policies, or protocols; management support; intersectoral coordination with clear, accessible on‐site and off‐site referral options; adequate and trained staff with accepting and empathetic attitudes toward survivors of IPV; initial and ongoing training for health workers; and a supportive and supervised environment in which to enact new IPV protocols. A key characteristic of the most integrated responses was the connection or “linkages” between different individual factors. Irrespective of their service entry point, what emerged as crucial was a connected systems‐level response, with all elements implemented in a coordinated manner. PMID:28422291

Norcantharidin Facilitates LPS-Mediated Immune Responses by Up-Regulation of AKT/NF-κB Signaling in Macrophages

PubMed Central

Li, Ruimei; Tan, Binghe; Han, Honghui; Liu, Mingyao; Qian, Min; Du, Bing

2012-01-01

Norcantharidin (NCTD), a demethylated analog of cantharidin, is a common used clinical drug to inhibit proliferation and metastasis of cancer cells. But the role of NCTD in modulating immune responses remains unknown. Here, we investigated the function and mechanism of NCTD in regulation of TLR4 associated immune response in macrophages. We evaluated the influence of NCTD on host defense against invaded pathogens by acute peritonitis mouse model, ELISA, Q-PCR, nitrite quantification, phagocytosis assay and gelatin zymography assay. Our data showed that the survival and the serum concentrations of IL-6 and TNF-α were all enhanced by NCTD significantly in peritonitis mouse model. Accordingly, LPS-induced cytokine, nitric oxide and MMP-9 production as well as the phagocytosis of bacteria were all up-regulated by NCTD in a dose dependent manner in both RAW264.7 cells and bone marrow-derived macrophages (BMMs). Then we further analyzed TLR4 associated signaling pathway by Western blot, Immunofluorescence and EMSA in the presence or absence of LPS. The phosphorylation of AKT and p65 at serine 536 but not serine 468 was enhanced obviously by NCTD in a dose dependent manner, whereas the degradation of IκBα was little effected. Consequently, the nuclear translocation and DNA binding ability of NF-κB was also increased by NCTD obviously in RAW264.7 cells. Our results demonstrated that NCTD could facilitate LPS-mediated immune response through promoting the phosphorylation of AKT/p65 and transcriptional activity of NF-κB, thus reprofiling the traditional anti-tumor drug NCTD as a novel immune regulator in promoting host defense against bacterial infection. PMID:22984593

Facilitating Lecturer Development and Student Learning through Action Research

ERIC Educational Resources Information Center

van der Westhuizen, C. N.

2008-01-01

The aim of the action research project is to improve my own practice as research methodology lecturer to facilitate effective student learning to enable students to become reflective practitioners with responsibility for their own professional development through action research in their own classrooms, and to motivate the students and increase…

Teacher’s Mathematical Communication Profile in Facilitating and Guiding Discussion

NASA Astrophysics Data System (ADS)

Umami, R.; Budayasa, I. K.; Suwarsono, St.

2018-01-01

Teacher’s communication skill plays an important role, one of which is to guide a class discussion for teaching purposes. This study aimed to investigate a teacher’s mathematical communication profile in facilitating and guiding a class discussion. This study is qualitative. A junior teacher of high school (i.e., a teacher with 1 to 5 year teaching experience) teaching mathematics at X-Social Class was selected as the subject of this study. The data was collected by observing the teacher’s mathematical communication in facilitating and guiding a discussion with the rules of sinus as the teaching material, and it was followed by a deep interview. The result showed that the junior teacher facilitated and guided a class discussion include providing responses (answer) addressing students’ difficulties and providing chances for students to propose and explain their ideas and be active in discussion. The junior teacher provides responses at sharp, optimal, and specific manner. In addition, she provides chances for her students to explain their thinking and have a discussion in anticipative, observative, selective, and connective manner. However, the study found that some of high-school teachers develop mathematical communication skills and use them to develop students’ mathematical communication skills.

PlanetPack: A radial-velocity time-series analysis tool facilitating exoplanets detection, characterization, and dynamical simulations

NASA Astrophysics Data System (ADS)

Baluev, Roman V.

2013-08-01

We present PlanetPack, a new software tool that we developed to facilitate and standardize the advanced analysis of radial velocity (RV) data for the goal of exoplanets detection, characterization, and basic dynamical N-body simulations. PlanetPack is a command-line interpreter, that can run either in an interactive mode or in a batch mode of automatic script interpretation. Its major abilities include: (i) advanced RV curve fitting with the proper maximum-likelihood treatment of unknown RV jitter; (ii) user-friendly multi-Keplerian as well as Newtonian N-body RV fits; (iii) use of more efficient maximum-likelihood periodograms that involve the full multi-planet fitting (sometimes called as “residual” or “recursive” periodograms); (iv) easily calculatable parametric 2D likelihood function level contours, reflecting the asymptotic confidence regions; (v) fitting under some useful functional constraints is user-friendly; (vi) basic tasks of short- and long-term planetary dynamical simulation using a fast Everhart-type integrator based on Gauss-Legendre spacings; (vii) fitting the data with red noise (auto-correlated errors); (viii) various analytical and numerical methods for the tasks of determining the statistical significance. It is planned that further functionality may be added to PlanetPack in the future. During the development of this software, a lot of effort was made to improve the calculational speed, especially for CPU-demanding tasks. PlanetPack was written in pure C++ (standard of 1998/2003), and is expected to be compilable and useable on a wide range of platforms.

Understanding Facilitation: Theory and Principles.

ERIC Educational Resources Information Center

Hogan, Christine

This book introduces newcomers to the concept of facilitation, and it presents a critical analysis of established and current theory on facilitation for existing practitioners. The following are among the topics discussed: (1) emergence of the field of facilitation; (2) development of facilitation in management; (3) development of facilitation in…

Dynamic imperfections and optimized feedback design in the Compact Linear Collider main linac

NASA Astrophysics Data System (ADS)

Eliasson, Peder

2008-05-01

The Compact Linear Collider (CLIC) main linac is sensitive to dynamic imperfections such as element jitter, injected beam jitter, and ground motion. These effects cause emittance growth that, in case of ground motion, has to be counteracted by a trajectory feedback system. The feedback system itself will, due to jitter effects and imperfect beam position monitors (BPMs), indirectly cause emittance growth. Fast and accurate simulations of both the direct and indirect effects are desirable, but due to the many elements of the CLIC main linac, simulations may become very time consuming. In this paper, an efficient way of simulating linear (or nearly linear) dynamic effects is described. The method is also shown to facilitate the analytic determination of emittance growth caused by the different dynamic imperfections while using a trajectory feedback system. Emittance growth expressions are derived for quadrupole, accelerating structure, and beam jitter, for ground motion, and for noise in the feedback BPMs. Finally, it is shown how the method can be used to design a feedback system that is optimized for the optics of the machine and the ground motion spectrum of the particular site. This feedback system gives an emittance growth rate that is approximately 10 times lower than that of traditional trajectory feedbacks. The robustness of the optimized feedback system is studied for a number of additional imperfections, e.g., dipole corrector imperfections and faulty knowledge about the machine optics, with promising results.

Recognition-Based Physical Response to Facilitate EFL Learning

ERIC Educational Resources Information Center

Hwang, Wu-Yuin; Shih, Timothy K.; Yeh, Shih-Ching; Chou, Ke-Chien; Ma, Zhao-Heng; Sommool, Worapot

2014-01-01

This study, based on total physical response and cognitive psychology, proposed a Kinesthetic English Learning System (KELS), which utilized Microsoft's Kinect technology to build kinesthetic interaction with life-related contexts in English. A subject test with 39 tenth-grade students was conducted following empirical research method in order to…

NASA Instep/mdmsc Jitter Suppression Experiment (JITTER)

NASA Technical Reports Server (NTRS)

White, Edward V.

1992-01-01

The objectives are the following: (1) to develop and demonstrate in-space performance of both passive and active damping systems for suppression of micro-amplitude vibration on an actual application structure and operate despite uncertain dynamics and uncertain disturbance characteristics; and (2) to correlate ground and in-space performance - the performance metric is vibration attenuation. The goals are to achieve vibration suppression equivalent to 5 percent passive damping in selected models and 15 percent active damping in selected modes. Various aspects of this experiment are presented in viewgraph form.

Barriers and Facilitators to Integrating Health Service Responses to Intimate Partner Violence in Low- and Middle-Income Countries: A Comparative Health Systems and Service Analysis.

PubMed

Colombini, Manuela; Dockerty, Colleen; Mayhew, Susannah H

2017-06-01

This systematic review synthesizes 11 studies of health-sector responses to intimate partner violence (IPV) in low- and middle-income countries. The services that were most comprehensive and integrated in their responsiveness to IPV were primarily in primary health and antenatal care settings. Findings suggest that the following facilitators are important: availability of clear guidelines, policies, or protocols; management support; intersectoral coordination with clear, accessible on-site and off-site referral options; adequate and trained staff with accepting and empathetic attitudes toward survivors of IPV; initial and ongoing training for health workers; and a supportive and supervised environment in which to enact new IPV protocols. A key characteristic of the most integrated responses was the connection or "linkages" between different individual factors. Irrespective of their service entry point, what emerged as crucial was a connected systems-level response, with all elements implemented in a coordinated manner. © 2017 The Population Council, Inc.

Using dual-process theory and analogical transfer to explain facilitation on a hypothetico-deductive reasoning task.

PubMed

Koenig, Cynthia S; Platt, Richard D; Griggs, Richard A

2007-07-01

Using the analogical transfer paradigm, the present study investigated the competing explanations of Girotto and Legrenzi (Psychological Research 51: 129-135, 1993) and Griggs, Platt, Newstead, and Jackson (Thinking and Reasoning 4: 1-14, 1998) for facilitation on the SARS version of the THOG problem, a hypothetico-deductive reasoning task. Girotto and Legrenzi argue that facilitation is based on logical analysis of the task [System 2 reasoning in Evans's (Trends in Cognitive Sciences 7: 454-459, 2003) dual-process account of reasoning] while Griggs et al. maintain that facilitation is due to an attentional heuristic produced by the wording of the problem (System 1 reasoning). If Girotto and Legrenzi are correct, then System 2 reasoning, which is volitional and responsible for deductive reasoning, should be elicited, and participants should comprehend the solution principle of the THOG task and exhibit analogical transfer. However, if Griggs et al. are correct, then System 1 reasoning, which is responsible for heuristic problem solving strategies such as an attentional heuristic, should occur, and participants should not abstract the solution principle and transfer should not occur. Significant facilitation (68 and 82% correct) was only observed for the two SARS source problems, but significant analogical transfer did not occur. This lack of transfer suggests that System 1 reasoning was responsible for the facilitation observed in the SARS problem, supporting Griggs et al.'s attentional heuristic explanation. The present results also underscore the explanatory value of using analogical transfer rather than facilitation as the criterion for problem understanding.

Facilitation among plants in alpine environments in the face of climate change.

PubMed

Anthelme, Fabien; Cavieres, Lohengrin A; Dangles, Olivier

2014-01-01

While there is a large consensus that plant-plant interactions are a crucial component of the response of plant communities to the effects of climate change, available data remain scarce, particularly in alpine systems. This represents an important obstacle to making consistent predictions about the future of plant communities. Here, we review current knowledge on the effects of climate change on facilitation among alpine plant communities and propose directions for future research. In established alpine communities, while warming seemingly generates a net facilitation release, earlier snowmelt may increase facilitation. Some nurse plants are able to buffer microenvironmental changes in the long term and may ensure the persistence of other alpine plants through local migration events. For communities migrating to higher elevations, facilitation should play an important role in their reorganization because of the harsher environmental conditions. In particular, the absence of efficient nurse plants might slow down upward migration, possibly generating chains of extinction. Facilitation-climate change relationships are expected to shift along latitudinal gradients because (1) the magnitude of warming is predicted to vary along these gradients, and (2) alpine environments are significantly different at low vs. high latitudes. Data on these expected patterns are preliminary and thus need to be tested with further studies on facilitation among plants in alpine environments that have thus far not been considered. From a methodological standpoint, future studies will benefit from the spatial representation of the microclimatic environment of plants to predict their response to climate change. Moreover, the acquisition of long-term data on the dynamics of plant-plant interactions, either through permanent plots or chronosequences of glacial recession, may represent powerful approaches to clarify the relationship between plant interactions and climate change.

Reduced BOLD response to periodic visual stimulation.

PubMed

Parkes, Laura M; Fries, Pascal; Kerskens, Christian M; Norris, David G

2004-01-01

The blood oxygenation level-dependent (BOLD) response to entrained neuronal firing in the human visual cortex and lateral geniculate nuclei was investigated. Periodic checkerboard flashes at a range of frequencies (4-20 Hz) were used to drive the visual cortex neurons into entrained oscillatory firing. This is compared to a checkerboard flashing aperiodically, with the same average number of flashes per unit time. A magnetoencephalography (MEG) measurement was made to confirm that the periodic paradigm elicited entrainment. We found that for frequencies of 10 and 15 Hz, the periodic stimulus gave a smaller BOLD response than for the aperiodic stimulus. Detailed investigation at 15 Hz showed that the aperiodic stimulus gave a similar BOLD increase regardless of the magnitude of jitter (+/-17 ms compared to +/-33 ms), indicating that flashes need to be precise to at least 17 ms to maintain entrainment. This is also evidence that for aperiodic stimuli, the amplitude of the BOLD response ordinarily reflects the total number of flashes per unit time, irrespective of the precise spacing between them, suggesting that entrainment is the main cause of the BOLD reduction in the periodic condition. The results indicate that, during entrainment, there is a reduction in the neuronal metabolic demand. We suggest that because of the selective frequency band of this effect, it could be connected to synchronised reverberations around an internal feedback loop.

Facilitated versus Non-Facilitated Online Case Discussions: Comparing Differences in Problem Space Coverage

ERIC Educational Resources Information Center

Ertmer, Peggy A.; Koehler, Adrie A.

2015-01-01

The facilitator plays a key role in guiding students' efforts during case discussions. However, few studies have compared differences in learning outcomes for students participating in facilitated versus non-facilitated discussions. In this research, we used "problem space coverage" as a learning measure to compare outcomes between…

Prior expectations facilitate metacognition for perceptual decision.

PubMed

Sherman, M T; Seth, A K; Barrett, A B; Kanai, R

2015-09-01

The influential framework of 'predictive processing' suggests that prior probabilistic expectations influence, or even constitute, perceptual contents. This notion is evidenced by the facilitation of low-level perceptual processing by expectations. However, whether expectations can facilitate high-level components of perception remains unclear. We addressed this question by considering the influence of expectations on perceptual metacognition. To isolate the effects of expectation from those of attention we used a novel factorial design: expectation was manipulated by changing the probability that a Gabor target would be presented; attention was manipulated by instructing participants to perform or ignore a concurrent visual search task. We found that, independently of attention, metacognition improved when yes/no responses were congruent with expectations of target presence/absence. Results were modeled under a novel Bayesian signal detection theoretic framework which integrates bottom-up signal propagation with top-down influences, to provide a unified description of the mechanisms underlying perceptual decision and metacognition. Copyright © 2015 Elsevier Inc. All rights reserved.

Facilitation and refractoriness of the electrically evoked compound action potential.

PubMed

Hey, Matthias; Müller-Deile, Joachim; Hessel, Horst; Killian, Matthijs

2017-11-01

In this study we aim to resolve the contributions of facilitation and refractoriness at very short pulse intervals. Measurements of the refractory properties of the electrically evoked compound action potential (ECAP) of the auditory nerve in cochlear implant (CI) users at inter pulse intervals below 300 μs are influenced by facilitation and recovery effects. ECAPs were recorded using masker pulses with a wide range of current levels relative to the probe pulse levels, for three suprathreshold probe levels and pulse intervals from 13 to 200 μs. Evoked potentials were measured for 21 CI patients by using the masked response extraction artifact cancellation procedure. During analysis of the measurements the stimulation current was not used as absolute value, but in relation to the patient's individual ECAP threshold. This enabled a more general approach to describe facilitation as a probe level independent effect. Maximum facilitation was found for all tested inter pulse intervals at masker levels near patient's individual ECAP threshold, independent from probe level. For short inter pulse intervals an increased N 1 P 1 amplitude was measured for subthreshold masker levels down to 120 CL below patient's individual ECAP threshold in contrast to the recreated state. ECAPs recorded with inter pulse intervals up to 200 μs are influenced by facilitation and recovery. Facilitation effects are most pronounced for masker levels at or below ECAP threshold, while recovery effects increase with higher masker levels above ECAP threshold. The local maximum of the ECAP amplitude for masker levels around ECAP threshold can be explained by the mutual influence of maximum facilitation and minimal refractoriness. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Habitat-Mediated Facilitation and Counteracting Ecosystem Engineering Interactively Influence Ecosystem Responses to Disturbance

PubMed Central

Eklöf, Johan S.; van der Heide, Tjisse; Donadi, Serena; van der Zee, Els M.; O'Hara, Robert; Eriksson, Britas Klemens

2011-01-01

Recovery of an ecosystem following disturbance can be severely hampered or even shift altogether when a point disturbance exceeds a certain spatial threshold. Such scale-dependent dynamics may be caused by preemptive competition, but may also result from diminished self-facilitation due to weakened ecosystem engineering. Moreover, disturbance can facilitate colonization by engineering species that alter abiotic conditions in ways that exacerbate stress on the original species. Consequently, establishment of such counteracting engineers might reduce the spatial threshold for the disturbance, by effectively slowing recovery and increasing the risk for ecosystem shifts to alternative states. We tested these predictions in an intertidal mudflat characterized by a two-state mosaic of hummocks (humps exposed during low tide) dominated by the sediment-stabilizing seagrass Zostera noltii) and hollows (low-tide waterlogged depressions dominated by the bioturbating lugworm Arenicola marina). In contrast to expectations, seagrass recolonized both natural and experimental clearings via lateral expansion and seemed unaffected by both clearing size and lugworm addition. Near the end of the growth season, however, an additional disturbance (most likely waterfowl grazing and/or strong hydrodynamics) selectively impacted recolonizing seagrass in the largest (1 m2) clearings (regardless of lugworm addition), and in those medium (0.25 m2) clearings where lugworms had been added nearly five months earlier. Further analyses showed that the risk for the disturbance increased with hollow size, with a threshold of 0.24 m2. Hollows of that size were caused by seagrass removal alone in the largest clearings, and by a weaker seagrass removal effect exacerbated by lugworm bioturbation in the medium clearings. Consequently, a sufficiently large disturbance increased the vulnerability of recolonizing seagrass to additional disturbance by weakening seagrass engineering effects (sediment

Action relations facilitate the identification of briefly-presented objects.

PubMed

Roberts, Katherine L; Humphreys, Glyn W

2011-02-01

The link between perception and action allows us to interact fluently with the world. Objects which 'afford' an action elicit a visuomotor response, facilitating compatible responses. In addition, positioning objects to interact with one another appears to facilitate grouping, indicated by patients with extinction being better able to identify interacting objects (e.g. a corkscrew going towards the top of a wine bottle) than the same objects when positioned incorrectly for action (Riddoch, Humphreys, Edwards, Baker, & Willson, Nature Neuroscience, 6, 82-89, 2003). Here, we investigate the effect of action relations on the perception of normal participants. We found improved identification of briefly-presented objects when in correct versus incorrect co-locations for action. For the object that would be 'active' in the interaction (the corkscrew), this improvement was enhanced when it was oriented for use by the viewer's dominant hand. In contrast, the position-related benefit for the 'passive' object was stronger when the objects formed an action-related pair (corkscrew and bottle) compared with an unrelated pair (corkscrew and candle), and it was reduced when spatial cues disrupted grouping between the objects. We propose that these results indicate two separate effects of action relations on normal perception: a visuomotor response to objects which strongly afford an action; and a grouping effect between objects which form action-related pairs.

Medical Education to Enhance Critical Consciousness: Facilitators' Experiences.

PubMed

Zaidi, Zareen; Vyas, Rashmi; Verstegen, Danielle; Morahan, Page; Dornan, Tim

2017-11-01

To analyze educators' experiences of facilitating cultural discussions in two global health professions education programs and what these experiences had taught them about critical consciousness. A multicultural research team conducted in-depth interviews with 16 faculty who had extensive experience facilitating cultural discussions. They analyzed transcripts of the interviews thematically, drawing sensitizing insights from Gramsci's theory of cultural hegemony. Collaboration and conversation helped the team self-consciously examine their positions toward the data set and be critically reflexive. Participant faculty used their prior experience facilitating cultural discussions to create a "safe space" in which learners could develop critical consciousness. During multicultural interactions they recognized and explicitly addressed issues related to power differentials, racism, implicit bias, and gender bias. They noted the need to be "facile in attending to pain" as learners brought up traumatic experiences and other sensitive issues including racism and the impact of power dynamics. They built relationships with learners by juxtaposing and exploring the sometimes-conflicting norms of different cultures. Participants were reflective about their own understanding and tendency to be biased. They aimed to break free of such biases while role modeling how to have the courage to speak up. Experience had given facilitators in multicultural programs an understanding of their responsibility to promote critical consciousness and social justice. How faculty without prior experience or expertise could develop those values and skills is a topic for future research.

Social Facilitation: Effects of Audience and Manipulated Feedback on Performance.

ERIC Educational Resources Information Center

Koch, Christopher G.; And Others

Quality of performance feedback provided an individual may have pronounced impact on his motivation level and be at least partly responsible for social facilitation results. Male students (N=118) performed a dart-throwing task in the presence or absence of a three-person evaluative audience. After each of seven trials they received consistently…

Event-related theta oscillatory substrates for facilitation and interference effects of negative emotion on children's cognition.

PubMed

Jiang, Zhongqing; Waters, Allison C; Liu, Ying; Li, Wenhui; Yang, Lizhu

2017-06-01

We investigated the brain oscillatory contribution to emotion-cognition interaction in young children. Five-year-old participants (n=27) underwent EEG recording while engaged in a color identification task. Each trial began with an emotional prime. Response times indicated whether emotional primes facilitated or interfered with performance. Related effects were detected in theta-band power over parietal-occipital cortex, early in the response epoch (<500ms). Children in the emotion facilitation group showed greater theta synchronization for negative stimuli. The opposite trend was observed in the interference group. Results suggest a role for theta oscillations in children's adaptive response to emotional content in cognitive performance. Copyright © 2017 Elsevier B.V. All rights reserved.

The facilitating effect of positive emotions during an emotional Stroop task.

PubMed

Liu, Xingyu; Yang, Yisheng; Jiang, Songxiu; Li, Jie

2018-05-08

Prior research has shown that negative emotions, even though task irrelevant, are capable of delaying a participant's response to the color in which a negative emotional word is presented, a phenomenon known as the 'emotional Stroop effect'. However, relatively little is known about whether positive emotions have a similar or an opposite effect. The current study sets out to confirm the facilitating effect of positive emotions on color naming, which is predicted by Barbara Fredrickson's 'broaden and build' theory. Our results indicate that positive emotions did facilitate such processing in both of the study's experiments. We also found a significant difference in early posterior negativity amplitudes between positive and neutral stimuli, which was related to the 'fast effect'. Overall, the study's findings suggest that positive emotions can be detected quickly and automatically, and that this kind of prioritizing facilitates the ongoing cognitive processing.

An analysis of carrier phase jitter in an MPSK receiver utilizing map estimation. Ph.D. Thesis Semiannual Status Report, Jul. 1993 - Jan. 1994

NASA Technical Reports Server (NTRS)

Osborne, William P.

1994-01-01

The use of 8 and 16 PSK TCM to support satellite communications in an effort to achieve more bandwidth efficiency in a power-limited channel has been proposed. This project addresses the problem of carrier phase jitter in an M-PSK receiver utilizing the high SNR approximation to the maximum aposteriori estimation of carrier phase. In particular, numerical solutions to the 8 and 16 PSK self-noise and phase detector gain in the carrier tracking loop are presented. The effect of changing SNR on the loop noise bandwidth is also discussed. These data are then used to compute variance of phase error as a function of SNR. Simulation and hardware data are used to verify these calculations. The results show that there is a threshold in the variance of phase error versus SNR curves that is a strong function of SNR and a weak function of loop bandwidth. The M-PSK variance thresholds occur at SNR's in the range of practical interest for the use of 8 and 16-PSK TCM. This suggests that phase error variance is an important consideration in the design of these systems.

SNP analyses of postprandial responses in (an)orexigenic hormones and feelings of hunger reveal long-term physiological adaptations to facilitate homeostasis.

PubMed

den Hoed, M; Smeets, A J P G; Veldhorst, M A B; Nieuwenhuizen, A G; Bouwman, F G; Heidema, A G; Mariman, E C M; Westerterp-Plantenga, M S; Westerterp, K R

2008-12-01

The postprandial responses in (an)orexigenic hormones and feelings of hunger are characterized by large inter-individual differences. Food intake regulation was shown earlier to be partly under genetic control. This study aimed to determine whether the postprandial responses in (an)orexigenic hormones and parameters of food intake regulation are associated with single nucleotide polymorphisms (SNPs) in genes encoding for satiety hormones and their receptors. Peptide YY (PYY), glucagon-like peptide 1 and ghrelin levels, as well as feelings of hunger and satiety, were determined pre- and postprandially in 62 women and 41 men (age 31+/-14 years; body mass index 25.0+/-3.1 kg/m(2)). Dietary restraint, disinhibition and perceived hunger were determined using the three-factor eating questionnaire. SNPs were determined in the GHRL, GHSR, LEP, LEPR, PYY, NPY, NPY2R and CART genes. The postprandial response in plasma ghrelin levels was associated with SNPs in PYY (215G>C, P<0.01) and LEPR (326A>G and 688A>G, P<0.01), and in plasma PYY levels with SNPs in GHRL (-501A>C, P<0.05) and GHSR (477G>A, P<0.05). The postprandial response in feelings of hunger was characterized by an SNP-SNP interaction involving SNPs in LEPR and NPY2R (668A>G and 585T>C, P<0.05). Dietary restraint and disinhibition were associated with an SNP in GHSR (477G>A, P<0.05), and perceived hunger with SNPs in GHSR and NPY (477G>A and 204T>C, P<0.05). Part of the inter-individual variability in postprandial responses in (an)orexigenic hormones can be explained by genetic variation. These postprandial responses represent either long-term physiological adaptations to facilitate homeostasis or reinforce direct genetic effects.

Rapid response learning of brand logo priming: Evidence that brand priming is not dominated by rapid response learning.

PubMed

Boehm, Stephan G; Smith, Ciaran; Muench, Niklas; Noble, Kirsty; Atherton, Catherine

2017-08-31

Repetition priming increases the accuracy and speed of responses to repeatedly processed stimuli. Repetition priming can result from two complementary sources: rapid response learning and facilitation within perceptual and conceptual networks. In conceptual classification tasks, rapid response learning dominates priming of object recognition, but it does not dominate priming of person recognition. This suggests that the relative engagement of network facilitation and rapid response learning depends on the stimulus domain. Here, we addressed the importance of the stimulus domain for rapid response learning by investigating priming in another domain, brands. In three experiments, participants performed conceptual decisions for brand logos. Strong priming was present, but it was not dominated by rapid response learning. These findings add further support to the importance of the stimulus domain for the relative importance of network facilitation and rapid response learning, and they indicate that brand priming is more similar to person recognition priming than object recognition priming, perhaps because priming of both brands and persons requires individuation.

Cognitive processes facilitated by contextual cueing: evidence from event-related brain potentials.

PubMed

Schankin, Andrea; Schubö, Anna

2009-05-01

Finding a target in repeated search displays is faster than finding the same target in novel ones (contextual cueing). It is assumed that the visual context (the arrangement of the distracting objects) is used to guide attention efficiently to the target location. Alternatively, other factors, e.g., facilitation in early visual processing or in response selection, may play a role as well. In a contextual cueing experiment, participant's electrophysiological brain activity was recorded. Participants identified the target faster and more accurately in repeatedly presented displays. In this condition, the N2pc, a component reflecting the allocation of visual-spatial attention, was enhanced, indicating that attention was allocated more efficiently to those targets. However, also response-related processes, reflected by the LRP, were facilitated, indicating that guidance of attention cannot account for the entire contextual cueing benefit.

Experimental Sleep Restriction Facilitates Pain and Electrically Induced Cortical Responses.

PubMed

Matre, Dagfinn; Hu, Li; Viken, Leif A; Hjelle, Ingri B; Wigemyr, Monica; Knardahl, Stein; Sand, Trond; Nilsen, Kristian Bernhard

2015-10-01

Sleep restriction (SR) has been hypothesized to sensitize the pain system. The current study determined whether experimental sleep restriction had an effect on experimentally induced pain and pain-elicited electroencephalographic (EEG) responses. A paired crossover study. Pain testing was performed after 2 nights of 50% SR and after 2 nights with habitual sleep (HS). Laboratory experiment at research center. Self-reported healthy volunteers (n = 21, age range: 18-31 y). Brief high-density electrical stimuli to the forearm skin produced pinprick-like pain. Subjective pain ratings increased after SR, but only in response to the highest stimulus intensity (P = 0.018). SR increased the magnitude of the pain-elicited EEG response analyzed in the time-frequency domain (P = 0.021). Habituation across blocks did not differ between HS and SR. Event-related desynchronization (ERD) was reduced after SR (P = 0.039). Pressure pain threshold of the trapezius muscle region also decreased after SR (P = 0.017). Sleep restriction (SR) increased the sensitivity to pressure pain and to electrically induced pain of moderate, but not low, intensity. The increased electrical pain could not be explained by a difference in habituation. Increased response magnitude is possibly related to reduced processing within the somatosensory cortex after partial SR. © 2015 Associated Professional Sleep Societies, LLC.

Spiral ganglion cell site of excitation I: comparison of scala tympani and intrameatal electrode responses.

PubMed

Cartee, Lianne A; Miller, Charles A; van den Honert, Chris

2006-05-01

To determine the site of excitation on the spiral ganglion cell in response to electrical stimulation similar to that from a cochlear implant, single-fiber responses to electrical stimuli delivered by an electrode positioned in the scala tympani were compared to responses from stimuli delivered by an electrode placed in the internal auditory meatus. The response to intrameatal stimulation provided a control set of data with a known excitation site, the central axon of the spiral ganglion cell. For both intrameatal and scala tympani stimuli, the responses to single-pulse, summation, and refractory stimulus protocols were recorded. The data demonstrated that summation pulses, as opposed to single pulses, are likely to give the most insightful measures for determination of the site of excitation. Single-fiber summation data for both scala tympani and intrameatally stimulated fibers were analyzed with a clustering algorithm. Combining cluster analysis and additional numerical modeling data, it was hypothesized that the scala tympani responses corresponded to central excitation, peripheral excitation adjacent to the cell body, and peripheral excitation at a site distant from the cell body. Fibers stimulated by an intrameatal electrode demonstrated the greatest range of jitter measurements indicating that greater fiber independence may be achieved with intrameatal stimulation.

ATM facilitates mouse gammaherpesvirus reactivation from myeloid cells during chronic infection

PubMed Central

Kulinski, Joseph M.; Darrah, Eric J.; Broniowska, Katarzyna A.; Mboko, Wadzanai P.; Mounce, Bryan C.; Malherbe, Laurent P.; Corbett, John A; Gauld, Stephen B.; Tarakanova, Vera L.

2015-01-01

Gammaherpesviruses are cancer-associated pathogens that establish life-long infection in most adults. Insufficiency of Ataxia-Telangiectasia mutated (ATM) kinase leads to a poor control of chronic gammaherpesvirus infection via an unknown mechanism that likely involves a suboptimal antiviral response. In contrast to the phenotype in the intact host, ATM facilitates gammaherpesvirus reactivation and replication in vitro. We hypothesized that ATM mediates both pro- and antiviral activities to regulate chronic gammaherpesvirus infection in an immunocompetent host. To test the proposed proviral activity of ATM in vivo, we generated mice with ATM deficiency limited to myeloid cells. Myeloid-specific ATM deficiency attenuated gammaherpesvirus infection during the establishment of viral latency. The results of our study uncover a proviral role of ATM in the context of gammaherpesvirus infection in vivo and support a model where ATM combines pro- and antiviral functions to facilitate both gammaherpesvirus-specific T cell immune response and viral reactivation in vivo. PMID:26001649

ATM facilitates mouse gammaherpesvirus reactivation from myeloid cells during chronic infection.

PubMed

Kulinski, Joseph M; Darrah, Eric J; Broniowska, Katarzyna A; Mboko, Wadzanai P; Mounce, Bryan C; Malherbe, Laurent P; Corbett, John A; Gauld, Stephen B; Tarakanova, Vera L

2015-09-01

Gammaherpesviruses are cancer-associated pathogens that establish life-long infection in most adults. Insufficiency of Ataxia-Telangiectasia mutated (ATM) kinase leads to a poor control of chronic gammaherpesvirus infection via an unknown mechanism that likely involves a suboptimal antiviral response. In contrast to the phenotype in the intact host, ATM facilitates gammaherpesvirus reactivation and replication in vitro. We hypothesized that ATM mediates both pro- and antiviral activities to regulate chronic gammaherpesvirus infection in an immunocompetent host. To test the proposed proviral activity of ATM in vivo, we generated mice with ATM deficiency limited to myeloid cells. Myeloid-specific ATM deficiency attenuated gammaherpesvirus infection during the establishment of viral latency. The results of our study uncover a proviral role of ATM in the context of gammaherpesvirus infection in vivo and support a model where ATM combines pro- and antiviral functions to facilitate both gammaherpesvirus-specific T cell immune response and viral reactivation in vivo. Copyright © 2015 Elsevier Inc. All rights reserved.

Facilitators and Barriers to Health-Seeking Behaviours among Filipino Migrants: Inductive Analysis to Inform Health Promotion

PubMed Central

Salamonson, Y.; Descallar, J.; Davidson, P. M.

2015-01-01

Understanding factors that influence health-seeking behaviour of migrants is necessary to intervene for behaviour change. This paper explores Filipino migrants' perceptions of facilitators and barriers to maintaining health in Australia. Open-ended survey item responses reflecting factors that assisted and hindered health following migration to Australia were inductively analysed. Three hundred and thirty-seven of the 552 survey respondents (61%) provided open-ended responses. Responses were grouped into two major categories: individual factors, including personal resources and cultural influences, and environmental factors encompassing both the physical conditions in the host country and health service access. Awareness of practices that enhance health was a major personal facilitator of health-seeking behaviour; however, competing priorities of daily living were perceived as barriers. Cultural beliefs and practices influenced health-seeking behaviour. Despite high self-rated English language skills in this population, new migrants and the elderly cited communication difficulties as barriers to accessing health services. Insight into facilitators and barriers to health-seeking behaviour in this less researched migrant population revealed tools for enhancing engagement in health promotion programs addressing healthy lifestyle. PMID:26380277

Expression, purification, and functional characterization of the insulin-responsive facilitative glucose transporter GLUT4.

PubMed

Kraft, Thomas E; Hresko, Richard C; Hruz, Paul W

2015-12-01

The insulin-responsive facilitative glucose transporter GLUT4 is of fundamental importance for maintenance of glucose homeostasis. Despite intensive effort, the ability to express and purify sufficient quantities of structurally and functionally intact protein for biophysical analysis has previously been exceedingly difficult. We report here the development of novel methods to express, purify, and functionally reconstitute GLUT4 into detergent micelles and proteoliposomes. Rat GLUT4 containing FLAG and His tags at the amino and carboxy termini, respectively, was engineered and stably transfected into HEK-293 cells. Overexpression in suspension culture yielded over 1.5 mg of protein per liter of culture. Systematic screening of detergent solubilized GLUT4-GFP fusion protein via fluorescent-detection size exclusion chromatography identified lauryl maltose neopentyl glycol (LMNG) as highly effective for isolating monomeric GLUT4 micelles. Preservation of structural integrity and ligand binding was demonstrated via quenching of tryptophan fluorescence and competition of ATB-BMPA photolabeling by cytochalasin B. GLUT4 was reconstituted into lipid nanodiscs and proper folding was confirmed. Reconstitution of purified GLUT4 with amphipol A8-35 stabilized the transporter at elevated temperatures for extended periods of time. Functional activity of purified GLUT4 was confirmed by reconstitution of LMNG-purified GLUT4 into proteoliposomes and measurement of saturable uptake of D-glucose over L-glucose. Taken together, these data validate the development of an efficient means to generate milligram quantities of stable and functionally intact GLUT4 that is suitable for a wide array of biochemical and biophysical analyses. © 2015 The Protein Society.

Potent Cell-Intrinsic Immune Responses in Dendritic Cells Facilitate HIV-1-Specific T Cell Immunity in HIV-1 Elite Controllers.

PubMed

Martin-Gayo, Enrique; Buzon, Maria Jose; Ouyang, Zhengyu; Hickman, Taylor; Cronin, Jacqueline; Pimenova, Dina; Walker, Bruce D; Lichterfeld, Mathias; Yu, Xu G

2015-06-01

The majority of HIV-1 elite controllers (EC) restrict HIV-1 replication through highly functional HIV-1-specific T cell responses, but mechanisms supporting the evolution of effective HIV-1-specific T cell immunity in these patients remain undefined. Cytosolic immune recognition of HIV-1 in conventional dendritic cells (cDC) can facilitate priming and expansion of HIV-1-specific T cells; however, HIV-1 seems to be able to avoid intracellular immune recognition in cDCs in most infected individuals. Here, we show that exposure of cDCs from EC to HIV-1 leads to a rapid and sustained production of type I interferons and upregulation of several interferon-stimulated effector genes. Emergence of these cell-intrinsic immune responses was associated with a reduced induction of SAMHD1 and LEDGF/p75, and an accumulation of viral reverse transcripts, but inhibited by pharmacological blockade of viral reverse transcription or siRNA-mediated silencing of the cytosolic DNA sensor cGAS. Importantly, improved cell-intrinsic immune recognition of HIV-1 in cDCs from elite controllers translated into stronger abilities to stimulate and expand HIV-1-specific CD8 T cell responses. These data suggest an important role of cell-intrinsic type I interferon secretion in dendritic cells for the induction of effective HIV-1-specific CD8 T cells, and may be helpful for eliciting functional T cell immunity against HIV-1 for preventative or therapeutic clinical purposes.

Barriers and Facilitators of a Career as a Physician Scientist Among Rheumatologists in the United States

PubMed Central

Ogdie, Alexis; Shah, Ami A.; Makris, Una E.; Jiang, Yihui; Nelson, Amanda E.; Kim, Alfred H. J.; Angeles-Han, Sheila T.; Castelino, Flavia V.; Golding, Amit; Muscal, Eyal; Kahlenberg, J. Michelle; Barg, Frances K.

2015-01-01

Objectives To determine perceived barriers and facilitators to a career in rheumatology research, examine factors leading rheumatologists to leave an academic research career, and solicit ways to best support young physician-scientists. Methods A web-based survey was conducted among the domestic American College of Rheumatology (ACR) membership from January–March 2014. Inclusion criteria were ACR membership and an available email address. Non-rheumatologists were excluded. The survey assessed demographics, research participation, barriers and facilitators to a career in research, reasons for leaving a research career (when applicable), and ways in which the ACR could support junior investigators. Content analysis was used to extract relevant themes. Results Among 5,448 ACR domestic members, 502 responses were obtained (9.2% response rate). After exclusions (38 incomplete, 2 duplicates, 32 non-rheumatologists), 430 responses were analyzed. Participants included fellows, young investigators, established investigators, mentors, clinicians, and those who previously pursued a research career but have chosen a different career path. Funding and mentoring were the most highly ranked barriers and facilitators. Protection from clinical and administrative duties, institutional support and personal characteristics such as resilience and persistence were also ranked highly. The most commonly cited reasons for leaving an academic research career were difficulty obtaining funding and lack of department or division support. Conclusion This is the first study to examine barriers and facilitators to a career in rheumatology research from the perspectives of diverse groups of rheumatologists. Knowledge of such barriers and facilitators may assist in designing interventions to support investigators during vulnerable points in their career development. PMID:25708626

Crayfish neuromuscular facilitation activated by constant presynaptic action potentials and depolarizing pulses

PubMed Central

Zucker, Robert S.

1974-01-01

1. Experiments were conducted to test the hypothesis that facilitation of transmitter release in response to repetitive stimulation of the exciter motor axon to the crayfish claw opener muscle is due to an increase in the amplitude or duration of the action potential in presynaptic terminals. No consistent changes were found in the nerve terminal potential (n.t.p.) recorded extracellularly at synaptic sites on the surface of muscle fibres. 2. Apparent changes in n.t.p. are attributed to three causes. (i) Some recordings are shown to be contaminated by non-specific muscle responses which grow during facilitation. (ii) Some averaged n.t.p.s exhibit opposite changes in amplitude and duration which suggest a change in the synchrony of presynaptic nerve impulses at different frequencies. (iii) Some changes in n.t.p. are blocked by γ-methyl glutamate, an antagonist of the post-synaptic receptor, which suggests that these changes are caused by small muscle movements. 3. The only change in n.t.p. believed to represent an actual change in the intracellular signal is a reduction in n.t.p. amplitude to the second of two stimuli separated by a brief interval. 4. Tetra-ethyl ammonium ions increase synaptic transmission about 20% and prolong the n.t.p. about 15%. This result suggests that an increase in n.t.p. large enough to increase transmission by the several hundred per cent occurring during facilitation would be detected. 5. The nerve terminals are electrically excitable, and most synaptic sites have a diphasic or triphasic n.t.p., which suggests that the motor neurone terminals are actively invaded by nerve impulses. 6. When nerve impulses are blocked in tetrodotoxin, depolarization of nerve terminals increases the frequency of miniature excitatory junctional potentials (e.j.p.s), and a phasic e.j.p. can be evoked by large, brief depolarizing pulses. Responses to repetitive or paired depolarizations of constant amplitude and duration exhibit a facilitation similar to that

Crayfish neuromuscular facilitation activated by constant presynaptic action potentials and depolarizing pulses.

PubMed

Zucker, R S

1974-08-01

1. Experiments were conducted to test the hypothesis that facilitation of transmitter release in response to repetitive stimulation of the exciter motor axon to the crayfish claw opener muscle is due to an increase in the amplitude or duration of the action potential in presynaptic terminals. No consistent changes were found in the nerve terminal potential (n.t.p.) recorded extracellularly at synaptic sites on the surface of muscle fibres.2. Apparent changes in n.t.p. are attributed to three causes.(i) Some recordings are shown to be contaminated by non-specific muscle responses which grow during facilitation.(ii) Some averaged n.t.p.s exhibit opposite changes in amplitude and duration which suggest a change in the synchrony of presynaptic nerve impulses at different frequencies.(iii) Some changes in n.t.p. are blocked by gamma-methyl glutamate, an antagonist of the post-synaptic receptor, which suggests that these changes are caused by small muscle movements.3. The only change in n.t.p. believed to represent an actual change in the intracellular signal is a reduction in n.t.p. amplitude to the second of two stimuli separated by a brief interval.4. Tetra-ethyl ammonium ions increase synaptic transmission about 20% and prolong the n.t.p. about 15%. This result suggests that an increase in n.t.p. large enough to increase transmission by the several hundred per cent occurring during facilitation would be detected.5. The nerve terminals are electrically excitable, and most synaptic sites have a diphasic or triphasic n.t.p., which suggests that the motor neurone terminals are actively invaded by nerve impulses.6. When nerve impulses are blocked in tetrodotoxin, depolarization of nerve terminals increases the frequency of miniature excitatory junctional potentials (e.j.p.s), and a phasic e.j.p. can be evoked by large, brief depolarizing pulses. Responses to repetitive or paired depolarizations of constant amplitude and duration exhibit a facilitation similar to that of e

Threat facilitates subsequent executive control during anxious mood.

PubMed

Birk, Jeffrey L; Dennis, Tracy A; Shin, Lisa M; Urry, Heather L

2011-12-01

Dual competition framework (DCF) posits that low-level threat may facilitate behavioral performance by influencing executive control functions. Anxiety is thought to strengthen this effect by enhancing threat's affective significance. To test these ideas directly, we examined the effects of low-level threat and experimentally induced anxiety on one executive control function, the efficiency of response inhibition. In Study 1, briefly presented stimuli that were mildly threatening (i.e., fearful faces) relative to nonthreatening (i.e., neutral faces) led to facilitated executive control efficiency during experimentally induced anxiety. No such effect was observed during an equally arousing, experimentally induced happy mood state. In Study 2, we assessed the effects of low-level threat, experimentally induced anxiety, and individual differences in trait anxiety on executive control efficiency. Consistent with Study 1, fearful relative to neutral faces led to facilitated executive control efficiency during experimentally induced anxiety. No such effect was observed during an experimentally induced neutral mood state. Moreover, individual differences in trait anxiety did not moderate the effects of threat and anxiety on executive control efficiency. The findings are partially consistent with the predictions of DCF in that low-level threat improved executive control, at least during a state of anxiety. (c) 2011 APA, all rights reserved.

Characterization of gigahertz (GHz) bandwidth photomultipliers

NASA Technical Reports Server (NTRS)

Abshire, J. B.; Rowe, H. E.

1977-01-01

The average impulse response, root-mean-square times jitter as a function of signal level, single photoelectron distribution, and multiphotoelectron dark-count distribution have been measured for two static crossed-field and five electrostatic photomultipliers. The optical signal source for the first three of these tests was a 30 picosecond mode-locked laser pulse at 0.53 micron. The static crossed-field detectors had 2-photoelectron resolution, less than 200 ps rise times, and rms time jitters of 30 ps at the single photoelectron level. The electrostatic photomultipliers had rise times from 1 to 2.5 nanoseconds, and rms time jitters from 160 to 650 ps at the same signal level. The two static crossed-field photomultipliers had ion-feedback-generated dark pulses to the 50-photoelectron level, whereas one electrostatic photomultiplier had dark pulses to the 30-photoelectron level.

Teachers' Report of Strategies Used to Facilitate Language Development in Students with Hearing Loss

ERIC Educational Resources Information Center

Handley, Candace Michele

2013-01-01

The purpose of this study was to identify the extent to which teachers of the deaf report using four identified language facilitation strategies: recasting, extension, responsivity, and self-talk/parallel talk. Participants self-selected in response to an advertisement on a state-wide listserv and to the state's residential school internal news.…

Facilitation among plants in alpine environments in the face of climate change

PubMed Central

Anthelme, Fabien; Cavieres, Lohengrin A.; Dangles, Olivier

2014-01-01

While there is a large consensus that plant–plant interactions are a crucial component of the response of plant communities to the effects of climate change, available data remain scarce, particularly in alpine systems. This represents an important obstacle to making consistent predictions about the future of plant communities. Here, we review current knowledge on the effects of climate change on facilitation among alpine plant communities and propose directions for future research. In established alpine communities, while warming seemingly generates a net facilitation release, earlier snowmelt may increase facilitation. Some nurse plants are able to buffer microenvironmental changes in the long term and may ensure the persistence of other alpine plants through local migration events. For communities migrating to higher elevations, facilitation should play an important role in their reorganization because of the harsher environmental conditions. In particular, the absence of efficient nurse plants might slow down upward migration, possibly generating chains of extinction. Facilitation–climate change relationships are expected to shift along latitudinal gradients because (1) the magnitude of warming is predicted to vary along these gradients, and (2) alpine environments are significantly different at low vs. high latitudes. Data on these expected patterns are preliminary and thus need to be tested with further studies on facilitation among plants in alpine environments that have thus far not been considered. From a methodological standpoint, future studies will benefit from the spatial representation of the microclimatic environment of plants to predict their response to climate change. Moreover, the acquisition of long-term data on the dynamics of plant–plant interactions, either through permanent plots or chronosequences of glacial recession, may represent powerful approaches to clarify the relationship between plant interactions and climate change. PMID

Working alone or in the presence of others: exploring social facilitation in baggage X-ray security screening tasks.

PubMed

Yu, Rui-feng; Wu, Xin

2015-01-01

This study investigated whether the mere presence of a human audience would evoke a social facilitation effect in baggage X-ray security screening tasks. A 2 (target presence: present vs. absent) ×  2 (task complexity: simple vs. complex) ×  2 (social presence: alone vs. human audience) within-subject experiment simulating a real baggage screening task was conducted. This experiment included 20 male participants. The participants' search performance in this task was recorded. The results showed that the presence of a human audience speeded up responses in simple tasks and slowed down responses in complex tasks. However, the social facilitation effect produced by the presence of a human audience had no effect on response accuracy. These findings suggested that the complexity of screening tasks should be considered when designing work organisation modes for security screening tasks. Practitioner summary: This study investigated whether the presence of a human audience could evoke a social facilitation effect in baggage X-ray security screening tasks. An experimental simulation was conducted. The results showed that the presence of a human audience facilitated the search performance of simple tasks and inhibited the performance of complex tasks.

Facilitating Facilitators to Facilitate, in Problem or Enquiry Based Learning Sessions

ERIC Educational Resources Information Center

Coelho, Catherine

2014-01-01

Problem based learning (PBL) has been used in dental education over the past 20 years and uses a patient case scenario to stimulate learning in a small group setting, where a trained facilitator does not teach but guides the group to bring about deep contextualized learning, to be empathetic to each other and to encourage fair and equitable…

Family Engagement in Schoolwide Positive Behavioral Interventions and Supports: Barriers and Facilitators to Implementation.

PubMed

Garbacz, S Andrew; Hirano, Kara; McIntosh, Kent; Eagle, John W; Minch, Devon; Vatland, Christopher

2017-11-20

The purpose of this study was to identify barriers and facilitators to family engagement in schools implementing schoolwide positive behavioral interventions and supports (PBIS). Participants consisted of 1 representative member each from 204 school PBIS teams across 3 states. Qualitative analysis guided examination of responses to 1 question regarding barriers and 2 questions about facilitators to family engagement. Survey respondents identified key barriers to family engagement as a lack of resources, inconsistent communication, and reluctance of families and school staff to partner. Specified facilitators included communication, PBIS, shared decision-making, and strategies to build relationships with families. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Barriers and facilitators of sports in Dutch Paralympic athletes: An explorative study.

PubMed

Jaarsma, E A; Geertzen, J H B; de Jong, R; Dijkstra, P U; Dekker, R

2014-10-01

The purpose of this study was to gain insight in barriers and facilitators of sports in paralympic athletes. An online questionnaire was distributed through the Netherlands Olympic Committee and National Sports Confederation to determine personal and environmental barriers and facilitators of sports participation. The International Classification of Functioning, Disability and Health model and theory of planned behavior were used to respectively categorize the results in environmental and personal factors, and attitude, subjective norm and perceived behavioral control. Seventy-six Dutch Paralympic athletes completed the questionnaire (51% response rate). Barriers and facilitators experienced by ambulant and wheelchair athletes were compared. Most frequently mentioned personal barrier was dependency of others (22%), while most frequently mentioned environmental barrier was lack of sports facilities (30%). Wheelchair athletes mentioned more barriers (median = 3, interquartile range: 0.5-6), than ambulant athletes (median = 1.0,interquartile range:0.0-3.0, P = 0.023). One-third of the athletes did not experience any barriers. Most frequently mentioned personal facilitators to initiate sports participation were fun (78%), health (61%), and competition (53%). Most frequently mentioned environmental facilitator was social support (40%). This study indicated that barriers of sport were mostly environmental, while facilitators were usually personal factors. Attitude and subjective norm were considered the most important components for intention to participation in sports. The facilitators outweighed the barriers and kept the athletes being active in sports. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Residents' Exposure to Educational Experiences in Facilitating Hospital Discharges

PubMed Central

Stickrath, Chad; McNulty, Monica; Calderon, Aaron J.; Chapman, Elizabeth; Gonzalo, Jed D.; Kuperman, Ethan F.; Lopez, Max; Smith, Christopher J.; Sweigart, Joseph R.; Theobald, Cecelia N.; Burke, Robert E.

2017-01-01

Background There is an incomplete understanding of the most effective approaches for motivating residents to adopt guideline-recommended practices for hospital discharges. Objective We evaluated internal medicine (IM) residents' exposure to educational experiences focused on facilitating hospital discharges and compared those experiences based on correlations with residents' perceived responsibility for safely transitioning patients from the hospital. Methods A cross-sectional, multi-center survey of IM residents at 9 US university- and community-based training programs in 2014–2015 measured exposure to 8 transitional care experiences, their perceived impact on care transitions attitudes, and the correlation between experiences and residents' perceptions of postdischarge responsibility. Results Of 817 residents surveyed, 469 (57%) responded. Teaching about care transitions on rounds was the most common educational experience reported by residents (74%, 327 of 439). Learning opportunities with postdischarge patient contact were less common (clinic visits: 32%, 142 of 439; telephone calls: 12%, 53 of 439; and home visits: 4%, 18 of 439). On a 1–10 scale (10 = highest impact), residents rated postdischarge clinic as having the highest impact on their motivation to ensure safe transitions of care (mean = 7.61). Prior experiences with a postdischarge clinic visit, home visit, or telephone call were each correlated with increased perceived responsibility for transitional care tasks (correlation coefficients 0.12 [P = .004], 0.1 [P = .012], and 0.13 [P =  001], respectively). Conclusions IM residents learn to facilitate hospital discharges most often through direct patient care. Opportunities to interact with patients across the postdischarge continuum are uncommon, despite correlating with increased perceived responsibility for ensuring safe transitions of care. PMID:28439351

AKT phosphorylates H3-threonine 45 to facilitate termination of gene transcription in response to DNA damage.

PubMed

Lee, Jong-Hyuk; Kang, Byung-Hee; Jang, Hyonchol; Kim, Tae Wan; Choi, Jinmi; Kwak, Sojung; Han, Jungwon; Cho, Eun-Jung; Youn, Hong-Duk

2015-05-19

Post-translational modifications of core histones affect various cellular processes, primarily through transcription. However, their relationship with the termination of transcription has remained largely unknown. In this study, we show that DNA damage-activated AKT phosphorylates threonine 45 of core histone H3 (H3-T45). By genome-wide chromatin immunoprecipitation sequencing (ChIP-seq) analysis, H3-T45 phosphorylation was distributed throughout DNA damage-responsive gene loci, particularly immediately after the transcription termination site. H3-T45 phosphorylation pattern showed close-resemblance to that of RNA polymerase II C-terminal domain (CTD) serine 2 phosphorylation, which establishes the transcription termination signal. AKT1 was more effective than AKT2 in phosphorylating H3-T45. Blocking H3-T45 phosphorylation by inhibiting AKT or through amino acid substitution limited RNA decay downstream of mRNA cleavage sites and decreased RNA polymerase II release from chromatin. Our findings suggest that AKT-mediated phosphorylation of H3-T45 regulates the processing of the 3' end of DNA damage-activated genes to facilitate transcriptional termination. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

The informativity of sound modulates crossmodal facilitation of visual discrimination: a fMRI study.

PubMed

Li, Qi; Yu, Hongtao; Li, Xiujun; Sun, Hongzan; Yang, Jingjing; Li, Chunlin

2017-01-18

Many studies have investigated behavioral crossmodal facilitation when a visual stimulus is accompanied by a concurrent task-irrelevant sound. Lippert and colleagues reported that a concurrent task-irrelevant sound reduced the uncertainty of the timing of the visual display and improved perceptional responses (informative sound). However, the neural mechanism by which the informativity of sound affected crossmodal facilitation of visual discrimination remained unclear. In this study, we used event-related functional MRI to investigate the neural mechanisms underlying the role of informativity of sound in crossmodal facilitation of visual discrimination. Significantly faster reaction times were observed when there was an informative relationship between auditory and visual stimuli. The functional MRI results showed sound informativity-induced activation enhancement including the left fusiform gyrus and the right lateral occipital complex. Further correlation analysis showed that the right lateral occipital complex was significantly correlated with the behavioral benefit in reaction times. This suggests that this region was modulated by the informative relationship within audiovisual stimuli that was learnt during the experiment, resulting in late-stage multisensory integration and enhanced behavioral responses.

Verification of the Solar Dynamics Observatory High Gain Antenna Pointing Algorithm Using Flight Data

NASA Technical Reports Server (NTRS)

Bourkland, Kristin L.; Liu, Kuo-Chia

2011-01-01

The Solar Dynamics Observatory (SDO), launched in 2010, is a NASA-designed spacecraft built to study the Sun. SDO has tight pointing requirements and instruments that are sensitive to spacecraft jitter. Two High Gain Antennas (HGAs) are used to continuously send science data to a dedicated ground station. Preflight analysis showed that jitter resulting from motion of the HGAs was a cause for concern. Three jitter mitigation techniques were developed and implemented to overcome effects of jitter from different sources. These mitigation techniques include: the random step delay, stagger stepping, and the No Step Request (NSR). During the commissioning phase of the mission, a jitter test was performed onboard the spacecraft, in which various sources of jitter were examined to determine their level of effect on the instruments. During the HGA portion of the test, the jitter amplitudes from the single step of a gimbal were examined, as well as the amplitudes due to the execution of various gimbal rates. The jitter levels were compared with the gimbal jitter allocations for each instrument. The decision was made to consider implementing two of the jitter mitigating techniques on board the spacecraft: stagger stepping and the NSR. Flight data with and without jitter mitigation enabled was examined, and it is shown in this paper that HGA tracking is not negatively impacted with the addition of the jitter mitigation techniques. Additionally, the individual gimbal steps were examined, and it was confirmed that the stagger stepping and NSRs worked as designed. An Image Quality Test was performed to determine the amount of cumulative jitter from the reaction wheels, HGAs, and instruments during various combinations of typical operations. The HGA-induced jitter on the instruments is well within the jitter requirement when the stagger step and NSR mitigation options are enabled.

Facilitating Student Engagement: Social Responsibility and Freshmen Learning Communities

ERIC Educational Resources Information Center

Kingston, Lindsey N.; MacCartney, Danielle; Miller, Andrea

2014-01-01

Human rights education is advanced as a method for promoting social responsibility, with an emphasis on promoting ideals of "global citizenship" among undergraduate students. At the same time, the practice of learning communities is widespread on college campuses for retaining freshmen and promoting student success. However, there is…

Bacteria facilitate prey retention by the pitcher plant Darlingtonia californica

PubMed Central

2016-01-01

Bacteria are hypothesized to provide a variety of beneficial functions to plants. Many carnivorous pitcher plants, for example, rely on bacteria for digestion of captured prey. This bacterial community may also be responsible for the low surface tensions commonly observed in pitcher plant digestive fluids, which might facilitate prey capture. I tested this hypothesis by comparing the physical properties of natural pitcher fluid from the pitcher plant Darlingtonia californica and cultured ‘artificial’ pitcher fluids and tested these fluids' prey retention capabilities. I found that cultures of pitcher leaves' bacterial communities had similar physical properties to raw pitcher fluids. These properties facilitated the retention of insects by both fluids and hint at a previously undescribed class of plant–microbe interaction. PMID:27881762

Bacteria facilitate prey retention by the pitcher plant Darlingtonia californica.

PubMed

Armitage, David W

2016-11-01

Bacteria are hypothesized to provide a variety of beneficial functions to plants. Many carnivorous pitcher plants, for example, rely on bacteria for digestion of captured prey. This bacterial community may also be responsible for the low surface tensions commonly observed in pitcher plant digestive fluids, which might facilitate prey capture. I tested this hypothesis by comparing the physical properties of natural pitcher fluid from the pitcher plant Darlingtonia californica and cultured 'artificial' pitcher fluids and tested these fluids' prey retention capabilities. I found that cultures of pitcher leaves' bacterial communities had similar physical properties to raw pitcher fluids. These properties facilitated the retention of insects by both fluids and hint at a previously undescribed class of plant-microbe interaction. © 2016 The Author(s).

Barriers to and Facilitators of a Career as a Physician-Scientist Among Rheumatologists in the US.

PubMed

Ogdie, Alexis; Shah, Ami A; Makris, Una E; Jiang, Yihui; Nelson, Amanda E; Kim, Alfred H J; Angeles-Han, Sheila T; Castelino, Flavia V; Golding, Amit; Muscal, Eyal; Kahlenberg, J Michelle; Barg, Frances K

2015-09-01

To determine perceived barriers to and facilitators of a career in rheumatology research, examine factors leading rheumatologists to leave an academic research career, and solicit ways to best support young physician-scientists. A web-based survey was conducted among the domestic American College of Rheumatology (ACR) membership from January through March 2014. Inclusion criteria were ACR membership and an available e-mail address. Non-rheumatologists were excluded. The survey assessed demographics, research participation, barriers to and facilitators of a career in research, reasons for leaving a research career (when applicable), and ways in which the ACR could support junior investigators. Content analysis was used to extract relevant themes. Among 5,448 domestic ACR members, 502 responses were obtained (9.2% response rate). After exclusions (38 incomplete, 2 duplicates, 32 non-rheumatologists), 430 responses were analyzed. Participants included fellows, young investigators, established investigators, mentors, clinicians, and those who previously pursued a research career but have chosen a different career path. Funding and mentoring were the most highly ranked barriers and facilitators. Protection from clinical and administrative duties, institutional support, and personal characteristics such as resilience and persistence were also ranked highly. The most commonly cited reasons for leaving an academic research career were difficulty obtaining funding and lack of department or division support. This is the first study to examine barriers to and facilitators of a career in rheumatology research from the perspectives of diverse groups of rheumatologists. Knowledge of such barriers and facilitators may assist in designing interventions to support investigators during vulnerable points in their career development. © 2015, American College of Rheumatology.

Facilitating Comprehension, Connection and Commitment to Environmentally Responsible Design

ERIC Educational Resources Information Center

Boehm, Sarah

2015-01-01

Given the increased awareness of the negative effects the building industry has on the environment, designs produced without considering sustainability of the planet can no longer be accepted. Although the concepts of sustainability and environmental responsibility are not new to the field of interior design, a review of the literature reveals…

Facilitating complex shape drawing in Williams syndrome and typical development.

PubMed

Hudson, Kerry D; Farran, Emily K

2013-07-01

Individuals with Williams syndrome (WS) produce drawings that are disorganised, likely due to an inability to replicate numerous spatial relations between parts. This study attempted to circumvent these drawing deficits in WS when copying complex combinations of one, two and three shapes. Drawing decisions were reduced by introducing a number of facilitators, for example, by using distinct colours and including facilitatory cues on the response sheet. Overall, facilitation improved drawing in the WS group to a comparable level of accuracy as typically developing participants (matched for non-verbal ability). Drawing accuracy was greatest in both groups when planning demands (e.g. starting location, line lengths and changes in direction) were reduced by use of coloured figures and providing easily distinguished and clearly grouped facilitatory cues to form each shape. This study provides the first encouraging evidence to suggest that drawing of complex shapes in WS can be facilitated; individuals with WS might be receptive to remediation programmes for drawing and handwriting. Copyright © 2013 Elsevier Ltd. All rights reserved.

Student Perceptions of Facilitators' Social Congruence, Use of Expertise and Cognitive Congruence in Problem-Based Learning

ERIC Educational Resources Information Center

Yew, Elaine H. J.; Yong, Janice J. Y.

2014-01-01

In problem-based learning (PBL), the role of a tutor or facilitator is different from what is typically considered as the role of a traditional teacher. In addition to being a subject-matter expert, the facilitator is also expected to be "socially" and "cognitively congruent". In this study, we analyze the survey responses from…

Developing facilitation skills--a narrative.

PubMed

Newton, Jennifer M

2003-07-01

Effective facilitation has been identified in the literature as one of three elements, along with context and evidence, that have a dynamic and coexisting relationship to enable the successful uptake of evidence into practice. This paper presents an overview of the concept of facilitation within the context of practice development, ahead of a personal and professional reflective account of a 'developing facilitator'. In the summer of 2001, the author was instrumental in organising the first Practice Development School in Melbourne. Thrown in at the deep end, she found herself co-facilitating with an experienced practice developer from the United Kingdom. Having never facilitated in the arena of an action learning group, nor worked in the field of practice development, there was initially a sense of impending overload and drowning in the new knowledge and skills that needed to be acquired. Drawing upon the work of narrative inquiry the author shares her experiences in the anticipation that in telling her story it will assist others in their journey of becoming a facilitator.

Evaluative priming in a semantic flanker task: ERP evidence for a mutual facilitation explanation.

PubMed

Schmitz, Melanie; Wentura, Dirk; Brinkmann, Thorsten A

2014-03-01

In semantic flanker tasks, target categorization response times are affected by the semantic compatibility of the flanker and target. With positive and negative category exemplars, we investigated the influence of evaluative congruency (whether flanker and target share evaluative valence) on the flanker effect, using behavioral and electrophysiological measures. We hypothesized a moderation of the flanker effect by evaluative congruency on the basis of the assumption that evaluatively congruent concepts mutually facilitate each other's activation (see Schmitz & Wentura in Journal of Experimental Psychology: Learning, Memory, and Cognition 38:984-1000, 2012). Applying an onset delay of 50 ms for the flanker, we aimed to decrease the facilitative effect of an evaluatively congruent flanker on target encoding and, at the same time, increase the facilitative effect of an evaluatively congruent target on flanker encoding. As a consequence of increased flanker activation in the case of evaluative congruency, we expected a semantically incompatible flanker to interfere with the target categorization to a larger extent (as compared with an evaluatively incongruent pairing). Confirming our hypotheses, the flanker effect significantly depended on evaluative congruency, in both mean response times and N2 mean amplitudes. Thus, the present study provided behavioral and electrophysiological evidence for the mutual facilitation of evaluatively congruent concepts. Implications for the representation of evaluative connotations of semantic concepts are discussed.

Medical students' and facilitators' experiences of an Early Professional Contact course: active and motivated students, strained facilitators.

PubMed

von Below, Bernhard; Hellquist, Gunilla; Rödjer, Stig; Gunnarsson, Ronny; Björkelund, Cecilia; Wahlqvist, Mats

2008-12-02

Today, medical students are introduced to patient contact, communication skills, and clinical examination in the preclinical years of the curriculum with the purpose of gaining clinical experience. These courses are often evaluated from the student perspective. Reports with an additional emphasis on the facilitator perspective are scarce. According to constructive alignment, an influential concept from research in higher education, the learning climate between students and teachers is also of great importance. In this paper, we approach the learning climate by studying both students' and facilitators' course experiences.In 2001, a new "Early Professional Contact" longitudinal strand through term 1-4, was introduced at the Sahlgrenska Academy, University of Gothenburg, Sweden. General practitioners and hospital specialists were facilitators.The aim of this study was to assess and analyse students' and clinical facilitators' experiences of the Early Professional Contact course and to illuminate facilitators' working conditions. Inspired by a Swedish adaptation of the Course Experience Questionnaire, an Early Professional Contact Questionnaire was constructed. In 2003, on the completion of the first longitudinal strand, a student and facilitator version was distributed to 86 students and 21 facilitators. In the analysis, both Chi-square and the Mann-Whitney tests were used. Sixty students (70%) and 15 facilitators (71%) completed the questionnaire. Both students and facilitators were satisfied with the course. Students reported gaining iiration for their future work as doctors along with increased confidence in meeting patients. They also reported increased motivation for biomedical studies. Differences in attitudes between facilitators and students were found. Facilitators experienced a greater workload, less reasonable demands and less support, than students. In this project, a new Early Professional Contact course was analysed from both student and facilitator

Treatment, Time, and Achievement: Do Searching Modes of Study Facilitate Learning?

ERIC Educational Resources Information Center

Rice, Marion J.

This report is a synthesis of five research studies comparing the facilitative effects on learning of searching and reception modes of study. The following five studies are discussed: (1) J.R. Dale, the effects on achievement of using the forced inferential response mode in an intermediate grade population-geography unit; (2) D.D. Dumbleton, the…

Attention to baseline: does orienting visuospatial attention really facilitate target detection?

PubMed

Albares, Marion; Criaud, Marion; Wardak, Claire; Nguyen, Song Chi Trung; Ben Hamed, Suliann; Boulinguez, Philippe

2011-08-01

Standard protocols testing the orientation of visuospatial attention usually present spatial cues before targets and compare valid-cue trials with invalid-cue trials. The valid/invalid contrast results in a relative behavioral or physiological difference that is generally interpreted as a benefit of attention orientation. However, growing evidence suggests that inhibitory control of response is closely involved in this kind of protocol that requires the subjects to withhold automatic responses to cues, probably biasing behavioral and physiological baselines. Here, we used two experiments to disentangle the inhibitory control of automatic responses from orienting of visuospatial attention in a saccadic reaction time task in humans, a variant of the classical cue-target detection task and a sustained visuospatial attentional task. Surprisingly, when referring to a simple target detection task in which there is no need to refrain from reacting to avoid inappropriate responses, we found no consistent evidence of facilitation of target detection at the attended location. Instead, we observed a cost at the unattended location. Departing from the classical view, our results suggest that reaction time measures of visuospatial attention probably relie on the attenuation of elementary processes involved in visual target detection and saccade initiation away from the attended location rather than on facilitation at the attended location. This highlights the need to use proper control conditions in experimental designs to disambiguate relative from absolute cueing benefits on target detection reaction times, both in psychophysical and neurophysiological studies.

Facilitating Grant Proposal Writing in Health Behaviors for University Faculty: A Descriptive Study

PubMed Central

Stein, L. A. R.; Clair, M.; Lebeau, R.; Prochaska, J. O.; Rossi, J. S.; Swift, J.

2015-01-01

Grant proposal writing in the behavioral sciences is important for fiscal reasons and scientific reasons at many universities. This report describes a grant proposal–writing seminar series provided to University faculty (N = 20) and explores factors facilitating and impeding writing. Summary statistics are provided for quantitative data. Free responses were sorted by independent raters into meaningful categories. As a consequence of the training, 45% planned to submit within 18 months; 80% of grant proposals targeted NIH. At 1-year follow-up, 40% actually submitted grants. Factors impeding grant proposal writing included competing professional demands; factors facilitating writing included regularly scheduled feedback on written proposal sections and access to expert collaborators. Obtaining grants generates financial resources, facilitates training experiences, and vastly contributes to the growth and dissemination of the knowledge base in an area. PMID:21444921

Mobilizing and Managing Social Capital: On Roles and Responsibilities of Local Facilitators in Territorial Development

ERIC Educational Resources Information Center

Schermer, Markus; Kirchengast, Christoph; Petit, Sandrine; Magnani, Natalia; Mieville-Ott, Valerie

2010-01-01

The paper explores the difficulties and challenges in mobilizing and managing social capital in concrete local and territorial directed rural development project activities. The main focus is put on the roles of local facilitators working with farmers and other local stakeholders during project implementation. The EU 5th framework project IMALP…

Introducing a multimedia course to enhance health professionals' skills to facilitate communities of practice.

PubMed

Jakubec, Sonya L; Parboosingh, John; Colvin, Barbara

2014-01-01

Scholarship about communities of practice (COP) is uncovering evidence that interactivity between community members contributes to improvement in practice. Leadership and facilitation are crucial elements of successful COP implementation. The purpose of this paper is to describe an innovative COP facilitator's course and report on the experiences of participants in the first course. In response to this need and emerging evidence, an on-line COP facilitator's course was developed and implemented in Alberta, Canada, in 2011. This course included a home-based COP practicum, introductory face-to-face session, an on-line discussion board moderated by faculty and on-line learning modules. Evaluation of the course was formalized in a qualitative study incorporating content analysis of postings, semi-structured interviews of successful participants and narrative responses to questions in a post course survey. A total of 15 of 22 participants perceived they acquired basic knowledge about community facilitation by completing the self-learning modules and assignments. Many did not establish home-based COP and only partially participated in the interactive components of the course. Six participants successfully completed the course by establishing home-based COP and actively participating in the social and interactive components of the course. They perceived they met course objectives and greatly benefited from participation in the course, in particular when they pushed themselves to facilitate in new and different ways, and when they were actively engaged with their home-based COP where they could practice and receive feedback. While the main reasons why participants dropped out or failed to complete all course components were reported, the experiences and perceptions of six participants who successfully completed all course components form the major part of the evaluation of the course and hence introduce bias. A more in depth analysis of why learners are reluctant to engage

Developmental trends in the facilitation of multisensory objects with distractors

PubMed Central

Downing, Harriet C.; Barutchu, Ayla; Crewther, Sheila G.

2015-01-01

Sensory integration and the ability to discriminate target objects from distractors are critical to survival, yet the developmental trajectories of these abilities are unknown. This study investigated developmental changes in 9- (n = 18) and 11-year-old (n = 20) children, adolescents (n = 19) and adults (n = 22) using an audiovisual object discrimination task with uni- and multisensory distractors. Reaction times (RTs) were slower with visual/audiovisual distractors, and although all groups demonstrated facilitation of multisensory RTs in these conditions, children's and adolescents' responses corresponded to fewer race model violations than adults', suggesting protracted maturation of multisensory processes. Multisensory facilitation could not be explained by changes in RT variability, suggesting that tests of race model violations may still have theoretical value at least for familiar multisensory stimuli. PMID:25653630

g-Jitter Mixed Convective Slip Flow of Nanofluid past a Permeable Stretching Sheet Embedded in a Darcian Porous Media with Variable Viscosity

PubMed Central

Uddin, Mohammed J.; Khan, Waqar A.; Amin, Norsarahaida S.

2014-01-01

The unsteady two-dimensional laminar g-Jitter mixed convective boundary layer flow of Cu-water and Al2O3-water nanofluids past a permeable stretching sheet in a Darcian porous is studied by using an implicit finite difference numerical method with quasi-linearization technique. It is assumed that the plate is subjected to velocity and thermal slip boundary conditions. We have considered temperature dependent viscosity. The governing boundary layer equations are converted into non-similar equations using suitable transformations, before being solved numerically. The transport equations have been shown to be controlled by a number of parameters including viscosity parameter, Darcy number, nanoparticle volume fraction, Prandtl number, velocity slip, thermal slip, suction/injection and mixed convection parameters. The dimensionless velocity and temperature profiles as well as friction factor and heat transfer rates are presented graphically and discussed. It is found that the velocity reduces with velocity slip parameter for both nanofluids for fluid with both constant and variable properties. It is further found that the skin friction decreases with both Darcy number and momentum slip parameter while it increases with viscosity variation parameter. The surface temperature increases as the dimensionless time increases for both nanofluids. Nusselt numbers increase with mixed convection parameter and Darcy numbers and decreases with the momentum slip. Excellent agreement is found between the numerical results of the present paper with published results. PMID:24927277

Online interprofessional education facilitation: A scoping review.

PubMed

Evans, Sherryn Maree; Ward, Catherine; Reeves, Scott

2018-04-22

The use of online media to deliver interprofessional education (IPE) is becoming more prevalent across health professions education settings. Facilitation of IPE activities is known to be critical to the effective delivery of IPE, however, specifics about the nature of online IPE facilitation remains unclear. To explore the health professions education literature to understand the extent, range and nature of research on online IPE facilitation. Scoping review methodology was used to guide a search of four electronic databases for relevant papers. Of the 2095 abstracts initially identified, after screening of both abstracts and full-text papers, 10 studies were selected for inclusion in this review. Following abstraction of key information from each study, a thematic analysis was undertaken. Three key themes emerged to describe the nature of the IPE facilitation literature: (1) types of online IPE facilitation contributions, (2) the experience of online IPE facilitation and (3) personal outcomes of online IPE facilitation. These IPE facilitation themes were particularly focused on facilitation of interprofessional student teams on an asynchronous basis. While the included studies provide some insight into the nature of online IPE facilitation, future research is needed to better understand facilitator contributions, and the facilitation experience and associated outcomes, both relating to synchronous and asynchronous online environments.

Supervision of Facilitators in a Multisite Study: Goals, Process, and Outcomes

PubMed Central

2010-01-01

Objective To describe the aims, implementation, and desired outcomes of facilitator supervision for both interventions (treatment and control) in Project Eban and to present the Eban Theoretical Framework for Supervision that guided the facilitators’ supervision. The qualifications and training of supervisors and facilitators are also described. Design This article provides a detailed description of supervision in a multisite behavioral intervention trial. The Eban Theoretical Framework for Supervision is guided by 3 theories: cognitive behavior therapy, the Life-long Model of Supervision, and “Empowering supervisees to empower others: a culturally responsive supervision model.” Methods Supervision is based on the Eban Theoretical Framework for Supervision, which provides guidelines for implementing both interventions using goals, process, and outcomes. Results Because of effective supervision, the interventions were implemented with fidelity to the protocol and were standard across the multiple sites. Conclusions Supervision of facilitators is a crucial aspect of multisite intervention research quality assurance. It provides them with expert advice, optimizes the effectiveness of facilitators, and increases adherence to the protocol across multiple sites. Based on the experience in this trial, some of the challenges that arise when conducting a multisite randomized control trial and how they can be handled by implementing the Eban Theoretical Framework for Supervision are described. PMID:18724192

Induced vibrations facilitate traversal of cluttered obstacles

NASA Astrophysics Data System (ADS)

Thoms, George; Yu, Siyuan; Kang, Yucheng; Li, Chen

When negotiating cluttered terrains such as grass-like beams, cockroaches and legged robots with rounded body shapes most often rolled their bodies to traverse narrow gaps between beams. Recent locomotion energy landscape modeling suggests that this locomotor pathway overcomes the lowest potential energy barriers. Here, we tested the hypothesis that body vibrations induced by intermittent leg-ground contact facilitate obstacle traversal by allowing exploration of locomotion energy landscape to find this lowest barrier pathway. To mimic a cockroach / legged robot pushing against two adjacent blades of grass, we developed an automated robotic system to move an ellipsoidal body into two adjacent beams, and varied body vibrations by controlling an oscillation actuator. A novel gyroscope mechanism allowed the body to freely rotate in response to interaction with the beams, and an IMU and cameras recorded the motion of the body and beams. We discovered that body vibrations facilitated body rolling, significantly increasing traversal probability and reducing traversal time (P <0.0001, ANOVA). Traversal probability increased with and traversal time decreased with beam separation. These results confirmed our hypothesis and support the plausibility of locomotion energy landscapes for understanding the formation of locomotor pathways in complex 3-D terrains.

Enhanced Facilitation of Spatial Attention in Schizophrenia

PubMed Central

Spencer, Kevin M.; Nestor, Paul G.; Valdman, Olga; Niznikiewicz, Margaret A.; Shenton, Martha E.; McCarley, Robert W.

2010-01-01

Objective While attentional functions are usually found to be impaired in schizophrenia, a review of the literature on the orienting of spatial attention in schizophrenia suggested that voluntary attentional orienting in response to a valid cue might be paradoxically enhanced. We tested this hypothesis with orienting tasks involving the cued detection of a laterally-presented target stimulus. Method Subjects were chronic schizophrenia patients (SZ) and matched healthy control subjects (HC). In Experiment 1 (15 SZ, 16 HC), cues were endogenous (arrows) and could be valid (100% predictive) or neutral with respect to the subsequent target position. In Experiment 2 (16 SZ, 16 HC), subjects performed a standard orienting task with unpredictive exogenous cues (brightening of the target boxes). Results In Experiment 1, SZ showed a larger attentional facilitation effect on reaction time than HC. In Experiment 2, no clear sign of enhanced attentional facilitation was found in SZ. Conclusions The voluntary, facilitatory shifting of spatial attention may be relatively enhanced in individuals with schizophrenia in comparison to healthy individuals. This effect bears resemblance to other relative enhancements of information processing in schizophrenia such as saccade speed and semantic priming. PMID:20919764

Enhanced facilitation of spatial attention in schizophrenia.

PubMed

Spencer, Kevin M; Nestor, Paul G; Valdman, Olga; Niznikiewicz, Margaret A; Shenton, Martha E; McCarley, Robert W

2011-01-01

While attentional functions are usually found to be impaired in schizophrenia, a review of the literature on the orienting of spatial attention in schizophrenia suggested that voluntary attentional orienting in response to a valid cue might be paradoxically enhanced. We tested this hypothesis with orienting tasks involving the cued detection of a laterally presented target stimulus. Subjects were chronic schizophrenia patients (SZ) and matched healthy control subjects (HC). In Experiment 1 (15 SZ, 16 HC), cues were endogenous (arrows) and could be valid (100% predictive) or neutral with respect to the subsequent target position. In Experiment 2 (16 SZ, 16 HC), subjects performed a standard orienting task with unpredictive exogenous cues (brightening of the target boxes). In Experiment 1, SZ showed a larger attentional facilitation effect on reaction time than HC. In Experiment 2, no clear sign of enhanced attentional facilitation was found in SZ. The voluntary, facilitatory shifting of spatial attention may be relatively enhanced in individuals with schizophrenia in comparison to healthy individuals. This effect bears resemblance to other relative enhancements of information processing in schizophrenia such as saccade speed and semantic priming. (c) 2010 APA, all rights reserved.

Performance evaluation of digital phase-locked loops for advanced deep space transponders

NASA Technical Reports Server (NTRS)

Nguyen, T. M.; Hinedi, S. M.; Yeh, H.-G.; Kyriacou, C.

1994-01-01

The performances of the digital phase-locked loops (DPLL's) for the advanced deep-space transponders (ADT's) are investigated. DPLL's considered in this article are derived from the analog phase-locked loop, which is currently employed by the NASA standard deep space transponder, using S-domain to Z-domain mapping techniques. Three mappings are used to develop digital approximations of the standard deep space analog phase-locked loop, namely the bilinear transformation (BT), impulse invariant transformation (IIT), and step invariant transformation (SIT) techniques. The performance in terms of the closed loop phase and magnitude responses, carrier tracking jitter, and response of the loop to the phase offset (the difference between in incoming phase and reference phase) is evaluated for each digital approximation. Theoretical results of the carrier tracking jitter for command-on and command-off cases are then validated by computer simulation. Both theoretical and computer simulation results show that at high sampling frequency, the DPLL's approximated by all three transformations have the same tracking jitter. However, at low sampling frequency, the digital approximation using BT outperforms the others. The minimum sampling frequency for adequate tracking performance is determined for each digital approximation of the analog loop. In addition, computer simulation shows that the DPLL developed by BT provides faster response to the phase offset than IIT and SIT.

Attention and Facilitation: Converging Information versus Inadvertent Reading in Stroop Task Performance

ERIC Educational Resources Information Center

Roelofs, Ardi

2010-01-01

Disagreement exists about whether color-word Stroop facilitation is caused by converging information (e.g., Cohen et al., 1990; Roelofs, 2003) or inadvertent reading (MacLeod & MacDonald, 2000). Four experiments tested between these hypotheses by examining Stroop effects on response time (RT) both within and between languages. Words cannot be…

Masked response priming in expert typists.

PubMed

Heinemann, Alexander; Kiesel, Andrea; Pohl, Carsten; Kunde, Wilfried

2010-03-01

In masked priming tasks responses are usually faster when prime and target require identical rather than different responses. Previous research has extensively manipulated the nature and number of response-affording stimuli. However, little is known about the constraints of masked priming regarding the nature and number of response alternatives. The present study explored the limits of masked priming in a six-choice reaction time task, where responses from different fingers of both hands were required. We studied participants that were either experts for the type of response (skilled typists) or novices. Masked primes facilitated responding to targets that required the same response, responses with a different finger of the same hand, and with a homologous finger of the other hand. These effects were modulated by expertise. The results show that masked primes facilitate responding especially for experts in the S-R mapping and with increasing similarity of primed and required response.

A Family Response to the Drug Problem; A Family Program for the Prevention of Chemical Dependence with Group Facilitator Guidelines.

ERIC Educational Resources Information Center

1976

This manual, with accompanying facilitator's guide, presents a program for drug education designed for use by groups of families led by volunteer facilitators. The program offers an approach toward building better communications and understanding among family members. The program consists of six group sessions based on learning experiences…

The Resourceful Facilitator: Teacher Leaders Constructing Identities as Facilitators of Teacher Peer Groups

ERIC Educational Resources Information Center

Allen, David

2016-01-01

The use of teacher peer groups is a prevalent strategy for school-based professional development and instructional improvement. Facilitation of such groups is an increasingly vital dimension of teacher leadership as a component of school improvement efforts. Drawing on a qualitative study of facilitation of teacher peer groups, the article…

Speech rhythm facilitates syntactic ambiguity resolution: ERP evidence.

PubMed

Roncaglia-Denissen, Maria Paula; Schmidt-Kassow, Maren; Kotz, Sonja A

2013-01-01

In the current event-related potential (ERP) study, we investigated how speech rhythm impacts speech segmentation and facilitates the resolution of syntactic ambiguities in auditory sentence processing. Participants listened to syntactically ambiguous German subject- and object-first sentences that were spoken with either regular or irregular speech rhythm. Rhythmicity was established by a constant metric pattern of three unstressed syllables between two stressed ones that created rhythmic groups of constant size. Accuracy rates in a comprehension task revealed that participants understood rhythmically regular sentences better than rhythmically irregular ones. Furthermore, the mean amplitude of the P600 component was reduced in response to object-first sentences only when embedded in rhythmically regular but not rhythmically irregular context. This P600 reduction indicates facilitated processing of sentence structure possibly due to a decrease in processing costs for the less-preferred structure (object-first). Our data suggest an early and continuous use of rhythm by the syntactic parser and support language processing models assuming an interactive and incremental use of linguistic information during language processing.

Speech Rhythm Facilitates Syntactic Ambiguity Resolution: ERP Evidence

PubMed Central

Roncaglia-Denissen, Maria Paula; Schmidt-Kassow, Maren; Kotz, Sonja A.

2013-01-01

In the current event-related potential (ERP) study, we investigated how speech rhythm impacts speech segmentation and facilitates the resolution of syntactic ambiguities in auditory sentence processing. Participants listened to syntactically ambiguous German subject- and object-first sentences that were spoken with either regular or irregular speech rhythm. Rhythmicity was established by a constant metric pattern of three unstressed syllables between two stressed ones that created rhythmic groups of constant size. Accuracy rates in a comprehension task revealed that participants understood rhythmically regular sentences better than rhythmically irregular ones. Furthermore, the mean amplitude of the P600 component was reduced in response to object-first sentences only when embedded in rhythmically regular but not rhythmically irregular context. This P600 reduction indicates facilitated processing of sentence structure possibly due to a decrease in processing costs for the less-preferred structure (object-first). Our data suggest an early and continuous use of rhythm by the syntactic parser and support language processing models assuming an interactive and incremental use of linguistic information during language processing. PMID:23409109

Exploring the Supervisor Role as a Facilitator of Knowledge Sharing in Teams

ERIC Educational Resources Information Center

MacNeil, Christina Mary

2004-01-01

This paper explores the themes and implications, concerning the role of the supervisor as a facilitator of knowledge sharing in teams. After describing the strategic context for devolving human resource responsibilities to line managers, the paper defines and discusses the line manager/supervisor role. The barriers to learning in the workplace are…

Evaluation of the Facilitated Communication Pilot

ERIC Educational Resources Information Center

Cooper-Martin, Elizabeth

2014-01-01

The Office of Special Education and Student Services asked the Office of Shared Accountability to evaluate the "Facilitated Communication Pilot." In facilitated communication (FC), people with communication impairments express themselves by typing with the aid of a communication partner, called a facilitator, who provides physical (and…

Coral calcification mechanisms facilitate adaptive responses to ocean acidification.

PubMed

Schoepf, Verena; Jury, Christopher P; Toonen, Robert J; McCulloch, Malcolm T

2017-12-06

Ocean acidification (OA) is a pressing threat to reef-building corals, but it remains poorly understood how coral calcification is inhibited by OA and whether corals could acclimatize and/or adapt to OA. Using a novel geochemical approach, we reconstructed the carbonate chemistry of the calcifying fluid in two coral species using both a pH and dissolved inorganic carbon (DIC) proxy (δ 11 B and B/Ca, respectively). To address the potential for adaptive responses, both species were collected from two sites spanning a natural gradient in seawater pH and temperature, and then subjected to three pH T levels (8.04, 7.88, 7.71) crossed by two temperatures (control, +1.5°C) for 14 weeks. Corals from the site with naturally lower seawater pH calcified faster and maintained growth better under simulated OA than corals from the higher-pH site. This ability was consistently linked to higher pH yet lower DIC values in the calcifying fluid, suggesting that these differences are the result of long-term acclimatization and/or local adaptation to naturally lower seawater pH. Nevertheless, all corals elevated both pH and DIC significantly over seawater values, even under OA. This implies that high pH upregulation combined with moderate levels of DIC upregulation promote resistance and adaptive responses of coral calcification to OA. © 2017 The Author(s).

Using Web 2.0 Tools to Facilitate Case-Based Instruction: Considering the Possibilities

ERIC Educational Resources Information Center

Koehler, Adrie A.; Ertmer, Peggy A.

2016-01-01

Case-based instruction (CBI) offers a promising method for promoting problem-solving skills in learners. However, during CBI, the instructor shoulders major responsibility for shaping the learning that takes place. Research indicates that the facilitation techniques used during case discussions influence what gets covered, and to what extent,…

Subjective Accounts of the Turning Points that Facilitate Desistance From Intimate Partner Violence.

PubMed

Walker, Kate; Bowen, Erica; Brown, Sarah; Sleath, Emma

2017-03-01

The transition from persistence to desistance in male perpetrators of intimate partner violence (IPV) is an understudied phenomenon. This article examines the factors that initiate and facilitate primary desistance from IPV. The narratives of 22 male perpetrators of IPV (13 desisters and 9 persisters), 7 female survivors, and 9 programme (IPV interventions) facilitators, in England, were analysed using thematic analysis. In their accounts, the participants described how the change from persister to desister did not happen as a result of discrete unique incidents but instead occurred through a number of catalysts or stimuli of change. These triggers were experienced gradually and accumulated over time in number and in type. In particular, Negative consequences of violence and Negative emotional responses needed to accumulate so that the Point of resolve: Autonomous decision to change was finally realised. This process facilitated and initiated the path of change and thus primary desistance from IPV.

Implications of Mycobacterium Major Facilitator Superfamily for Novel Measures against Tuberculosis.

PubMed

Wang, Rui; Zhang, Zhen; Xie, Longxiang; Xie, Jianping

2015-01-01

Major facilitator superfamily (MFS) is an important secondary membrane transport protein superfamily conserved from prokaryotes to eukaryotes. The MFS proteins are widespread among bacteria and are responsible for the transfer of substrates. Pathogenic Mycobacterium MFS transporters, their distribution, function, phylogeny, and predicted crystal structures were studied to better understand the function of MFS and to discover specific inhibitors of MFS for better tuberculosis control.

Adenovirus Entry From the Apical Surface of Polarized Epithelia Is Facilitated by the Host Innate Immune Response

PubMed Central

Kotha, Poornima L. N.; Sharma, Priyanka; Kolawole, Abimbola O.; Yan, Ran; Alghamri, Mahmoud S.; Brockman, Trisha L.; Gomez-Cambronero, Julian; Excoffon, Katherine J. D. A.

2015-01-01

Prevention of viral-induced respiratory disease begins with an understanding of the factors that increase or decrease susceptibility to viral infection. The primary receptor for most adenoviruses is the coxsackievirus and adenovirus receptor (CAR), a cell-cell adhesion protein normally localized at the basolateral surface of polarized epithelia and involved in neutrophil transepithelial migration. Recently, an alternate isoform of CAR, CAREx8, has been identified at the apical surface of polarized airway epithelia and is implicated in viral infection from the apical surface. We hypothesized that the endogenous role of CAREx8 may be to facilitate host innate immunity. We show that IL-8, a proinflammatory cytokine and a neutrophil chemoattractant, stimulates the protein expression and apical localization of CAREx8 via activation of AKT/S6K and inhibition of GSK3β. Apical CAREx8 tethers infiltrating neutrophils at the apical surface of a polarized epithelium. Moreover, neutrophils present on the apical-epithelial surface enhance adenovirus entry into the epithelium. These findings suggest that adenovirus evolved to co-opt an innate immune response pathway that stimulates the expression of its primary receptor, apical CAREx8, to allow the initial infection the intact epithelium. In addition, CAREx8 is a new target for the development of novel therapeutics for both respiratory inflammatory disease and adenoviral infection. PMID:25768646

Group Facilitation: Functions and Skills.

ERIC Educational Resources Information Center

Anderson, L. Frances; Robertson, Sharon E.

1985-01-01

Discusses a model based on a specific set of assumptions about causality and effectiveness in interactional groups. Discusses personal qualities of group facilitators and proposes five major functions and seven skill clusters central to effective group facilitation. (Author/BH)

Effects of Student-Facilitated Learning on Instructional Facilitators

ERIC Educational Resources Information Center

Bonner, Sarah M.; Somers, Jennifer A.; Rivera, Gwendelyn J.; Keiler, Leslie S.

2017-01-01

We investigated perceptions about learning strategy use and instructional roles among a sample of high needs adolescents (n = 230) who acted as near-peer instructional facilitators. The sample was drawn from science and mathematics classes in nonselective public secondary schools in New York City. Students participated in an inschool intervention…

Facilitation of the arterial baroreflex by the preoptic area in anaesthetized rats.

PubMed Central

Inui, K; Nomura, J; Murase, S; Nosaka, S

1995-01-01

1. Activation of cell bodies in the ventrolateral part of the midbrain periaqueductal grey matter (PAG) facilitates the arterial baroreflex via the nucleus raphe magnus. The facilitatory effects of stimulation within the hypothalamus on the arterial baroreflex and their relation to the PAG and nucleus raphe magnus were studied in urethane- and chloralose-anaesthetized rats. 2. Systematic mapping experiments revealed that the preoptic area (POA) is the principal location in the hypothalamus of neuronal cell bodies that are responsible for the potentiation of the baroreflex. In addition to provoking hypotension and vagal bradycardia, both electrical and chemical stimulation of the POA produced facilitation of baroreflex vagal bradycardia (BVB) that was evoked by electrical stimulation of the aortic depressor nerve. Baroreflex hypotension was slightly augmented during activation of the POA in vagotomized rats. 3. Selective destruction of cell bodies either in the ventrolateral PAG or in the nucleus raphe magnus reduced facilitation of BVB by the POA. Hypotension and bradycardia due to POA stimulation were also markedly attenuated after such selective destruction. 4. In conclusion, the POA, the ventrolateral PAG and the nucleus raphe magnus constitute a functional complex that produces cardiovascular trophotropic effects including hypotension, vagal bradycardia and baroreflex facilitation. PMID:8568691

The potential role of postsynaptic phospholipase C activity in synaptic facilitation and behavioral sensitization in Aplysia.

PubMed

Fulton, Daniel; Condro, Michael C; Pearce, Kaycey; Glanzman, David L

2008-07-01

Previous findings indicate that synaptic facilitation, a cellular mechanism underlying sensitization of the siphon withdrawal response (SWR) in Aplysia, depends on a cascade of postsynaptic events, including activation of inositol triphosphate (IP3) receptors and release of Ca2+ from postsynaptic intracellular stores. These findings suggest that phospholipase C (PLC), the enzyme that catalyzes IP3 formation, may play an important role in postsynaptic signaling during facilitation and learning in Aplysia. Using the PLC inhibitor U73122, we found that PLC activity is required for synaptic facilitation following a 10-min treatment with 5-HT, as measured at 20 min after 5-HT washout. Prior work has indicated that facilitation at this time is supported primarily by postsynaptic processes. To determine whether postsynaptic PLC activity is involved in 5-HT-mediated facilitatory actions, we examined the effect of U73122 on enhancement of the response of motor neurons isolated in cell culture to glutamate, the sensory neuron transmitter. A 10-min application of 5-HT induced persistent (>40 min) enhancement of glutamate-evoked potentials (Glu-EPs) recorded from isolated motor neurons, and this enhancement was blocked by U73122. Finally, we showed that injecting U73122 into intact animals before behavioral training impaired intermediate-term sensitization, indicating that PLC activity contributes to this form of nonassociative learning.

Verification of the Solar Dynamics Observatory High Gain Antenna Pointing Algorithm Using Flight Data

NASA Technical Reports Server (NTRS)

Bourkland, Kristin L.; Liu, Kuo-Chia

2011-01-01

The Solar Dynamics Observatory (SDO) is a NASA spacecraft designed to study the Sun. It was launched on February 11, 2010 into a geosynchronous orbit, and uses a suite of attitude sensors and actuators to finely point the spacecraft at the Sun. SDO has three science instruments: the Atmospheric Imaging Assembly (AIA), the Helioseismic and Magnetic Imager (HMI), and the Extreme Ultraviolet Variability Experiment (EVE). SDO uses two High Gain Antennas (HGAs) to send science data to a dedicated ground station in White Sands, New Mexico. In order to meet the science data capture budget, the HGAs must be able to transmit data to the ground for a very large percentage of the time. Each HGA is a dual-axis antenna driven by stepper motors. Both antennas transmit data at all times, but only a single antenna is required in order to meet the transmission rate requirement. For portions of the year, one antenna or the other has an unobstructed view of the White Sands ground station. During other periods, however, the view from both antennas to the Earth is blocked for different portions of the day. During these times of blockage, the two HGAs take turns pointing to White Sands, with the other antenna pointing out to space. The HGAs handover White Sands transmission responsibilities to the unblocked antenna. There are two handover seasons per year, each lasting about 72 days, where the antennas hand off control every twelve hours. The non-tracking antenna slews back to the ground station by following a ground commanded trajectory and arrives approximately 5 minutes before the formerly tracking antenna slews away to point out into space. The SDO Attitude Control System (ACS) runs at 5 Hz, and the HGA Gimbal Control Electronics (GCE) run at 200 Hz. There are 40 opportunities for the gimbals to step each ACS cycle, with a hardware limitation of no more than one step every three GCE cycles. The ACS calculates the desired gimbal motion for tracking the ground station or for slewing

Patterned-ground facilitates shrub expansion in Low Arctic tundra

NASA Astrophysics Data System (ADS)

Frost, Gerald V.; Epstein, Howard E.; Walker, Donald A.; Matyshak, Georgiy; Ermokhina, Ksenia

2013-03-01

Recent expansion of tall shrubs in Low Arctic tundra is widely seen as a response to climate warming, but shrubification is not occurring as a simple function of regional climate trends. We show that establishment of tall alder (Alnus) is strongly facilitated by small, widely distributed cryogenic disturbances associated with patterned-ground landscapes. We identified expanding and newly established shrub stands at two northwest Siberian sites and observed that virtually all new shrubs occurred on bare microsites (‘circles’) that were disturbed by frost-heave. Frost-heave associated with circles is a widespread, annual phenomenon that maintains mosaics of mineral seedbeds with warm soils and few competitors that are immediately available to shrubs during favorable climatic periods. Circle facilitation of alder recruitment also plausibly explains the development of shrublands in which alders are regularly spaced. We conclude that alder abundance and extent have increased rapidly in the northwest Siberian Low Arctic since at least the mid-20th century, despite a lack of summer warming in recent decades. Our results are consistent with findings in the North American Arctic which emphasize that the responsiveness of Low Arctic landscapes to climate change is largely determined by the frequency and extent of disturbance processes that create mineral-rich seedbeds favorable for tall shrub recruitment. Northwest Siberia has high potential for continued expansion of tall shrubs and concomitant changes to ecosystem function, due to the widespread distribution of patterned-ground landscapes.

Fatal Attraction? Intraguild Facilitation and Suppression among Predators.

PubMed

Sivy, Kelly J; Pozzanghera, Casey B; Grace, James B; Prugh, Laura R

2017-11-01

Competition and suppression are recognized as dominant forces that structure predator communities. Facilitation via carrion provisioning, however, is a ubiquitous interaction among predators that could offset the strength of suppression. Understanding the relative importance of these positive and negative interactions is necessary to anticipate community-wide responses to apex predator declines and recoveries worldwide. Using state-sponsored wolf (Canis lupus) control in Alaska as a quasi experiment, we conducted snow track surveys of apex, meso-, and small predators to test for evidence of carnivore cascades (e.g., mesopredator release). We analyzed survey data using an integrative occupancy and structural equation modeling framework to quantify the strengths of hypothesized interaction pathways, and we evaluated fine-scale spatiotemporal responses of nonapex predators to wolf activity clusters identified from radio-collar data. Contrary to the carnivore cascade hypothesis, both meso- and small predator occupancy patterns indicated guild-wide, negative responses of nonapex predators to wolf abundance variations at the landscape scale. At the local scale, however, we observed a near guild-wide, positive response of nonapex predators to localized wolf activity. Local-scale association with apex predators due to scavenging could lead to landscape patterns of mesopredator suppression, suggesting a key link between occupancy patterns and the structure of predator communities at different spatial scales.

Fatal attraction? Intraguild facilitation and suppression among predators

USGS Publications Warehouse

Sivy, Kelly J.; Pozzanghera, Casey B.; Grace, James B.; Prugh, Laura R.

2017-01-01

Competition and suppression are recognized as dominant forces that structure predator communities. Facilitation via carrion provisioning, however, is a ubiquitous interaction among predators that could offset the strength of suppression. Understanding the relative importance of these positive and negative interactions is necessary to anticipate community-wide responses to apex predator declines and recoveries worldwide. Using state-sponsored wolf (Canis lupus) control in Alaska as a quasi experiment, we conducted snow track surveys of apex, meso-, and small predators to test for evidence of carnivore cascades (e.g., mesopredator release). We analyzed survey data using an integrative occupancy and structural equation modeling framework to quantify the strengths of hypothesized interaction pathways, and we evaluated fine-scale spatiotemporal responses of nonapex predators to wolf activity clusters identified from radio-collar data. Contrary to the carnivore cascade hypothesis, both meso- and small predator occupancy patterns indicated guild-wide, negative responses of nonapex predators to wolf abundance variations at the landscape scale. At the local scale, however, we observed a near guild-wide, positive response of nonapex predators to localized wolf activity. Local-scale association with apex predators due to scavenging could lead to landscape patterns of mesopredator suppression, suggesting a key link between occupancy patterns and the structure of predator communities at different spatial scales.

An extractables/leachables strategy facilitated by collaboration between drug product vendors and plastic material/system suppliers.

PubMed

Jenke, Dennis

2007-01-01

Leaching of plastic materials, packaging, or containment systems by finished drug products and/or their related solutions can happen when contact occurs between such materials, systems, and products. While the drug product vendor has the regulatory/legal responsibility to demonstrate that such leaching does not affect the safety, efficacy, and/or compliance of the finished drug product, the plastic's supplier can facilitate that demonstration by providing the drug product vendor with appropriate and relevant information. Although it is a reasonable expectation that suppliers would possess and share such facilitating information, it is not reasonable for vendors to expect suppliers to (1) reveal confidential information without appropriate safeguards and (2) possess information specific to the vendor's finished drug product. Any potential conflict between the vendor's desire for information and the supplier's willingness to either generate or supply such information can be mitigated if the roles and responsibilities of these two stakeholders are established up front. The vendor of the finished drug product is responsible for supplying regulators with a full and complete leachables assessment for its finished drug product. To facilitate (but not take the place of) the vendor's leachables assessment, suppliers of the materials, components, or systems can provide the vendor with a full and complete extractables assessment for their material/system. The vendor and supplier share the responsibility for reconciling or correlating the extractables and leachables data. While this document establishes the components of a full and complete extractables assessment, specifying the detailed process by which a full and complete extractables assessment is performed is beyond its scope.

A central site of action for benzamide facilitation of gastric emptying.

PubMed

Costall, B; Gunning, S J; Naylor, R J; Simpson, K H

1983-07-22

Gastric emptying of the fed guinea-pig was measured using a non-invasive X-ray fluoroscopic technique to determine passage from the stomach of polystyrene-coated barium sulphate spheroids. Peripherally administered metoclopramide (0.1-10 mg/kg i.p.), clebopride (1-10 mg/kg i.p.), (-)-sulpiride (40 mg/kg i.p.), haloperidol (1 mg/kg i.p.) and domperidone (1-10 mg/kg i.p.) failed to modify gastric emptying. Stress inhibited emptying, and this was considered to explain the effects of eserine and high dose metoclopramide. Gastric emptying was decreased by peripherally administered atropine (0.5 mg/kg i.p.) and apomorphine (0.1-0.5 mg/kg s.c.); the apomorphine response was antagonised by pretreatment with haloperidol, domperidone, (-)-sulpiride, metoclopramide and clebopride but not by prazosin + propranolol. Gastric emptying was facilitated by intracerebroventricular (i.c.v.) administrations of metoclopramide and clebopride (40, 100 and 200 micrograms) but not by i.c.v. domperidone, haloperidol, fluphenazine or (-)-sulpiride (100, 200 micrograms) and was inhibited by i.c.v. apomorphine (100, 200 micrograms); the response to i.c.v. apomorphine was antagonised by i.c.v. pretreatments with haloperidol, domperidone, (-)-sulpiride, metoclopramide and clebopride (40-50 micrograms). Facilitation of emptying by i.c.v. metoclopramide was prevented by peripheral pretreatment with atropine (0.5 mg/kg i.p.). It is concluded that the actions of apomorphine and metoclopramide/clebopride to respectively inhibit and facilitate gastric emptying may be mediated, at least in part, via central mechanisms. Whilst apomorphine's action may be mediated via dopamine receptor mechanisms, metoclopramide and clebopride act at additional unspecified sites, metoclopramide's action being expressed via cholinergic mechanisms.

Facilitated Communication: An Experimental Evaluation.

ERIC Educational Resources Information Center

Regal, Robert A.; And Others

1994-01-01

Nineteen adults with developmental disabilities, judged competent in facilitated communication, participated in a validation study using an information passing design requiring short-term recall of stimulus cards with shapes, colors, and numbers. Results failed to validate facilitated communication for the group as a whole, any individual…

Virtual OD: Facilitating Groups Online

ERIC Educational Resources Information Center

Milton, Judy; Watkins, Karen E.; Daley, Barbara J.

2005-01-01

This study examined the role of facilitators in nine virtual action learning groups. A qualitative analysis of the facilitators' interventions across all groups resulted in a typology that included group management, group process, and support interventions. A model showing the relationship among these categories proposes that effective…

Oxytocin selectively facilitates learning with social feedback and increases activity and functional connectivity in emotional memory and reward processing regions.

PubMed

Hu, Jiehui; Qi, Song; Becker, Benjamin; Luo, Lizhu; Gao, Shan; Gong, Qiyong; Hurlemann, René; Kendrick, Keith M

2015-06-01

In male Caucasian subjects, learning is facilitated by receipt of social compared with non-social feedback, and the neuropeptide oxytocin (OXT) facilitates this effect. In this study, we have first shown a cultural difference in that male Chinese subjects actually perform significantly worse in the same reinforcement associated learning task with social (emotional faces) compared with non-social feedback. Nevertheless, in two independent double-blind placebo (PLC) controlled between-subject design experiments we found OXT still selectively facilitated learning with social feedback. Similar to Caucasian subjects this OXT effect was strongest with feedback using female rather than male faces. One experiment performed in conjunction with functional magnetic resonance imaging showed that during the response, but not feedback phase of the task, OXT selectively increased activity in the amygdala, hippocampus, parahippocampal gyrus and putamen during the social feedback condition, and functional connectivity between the amygdala and insula and caudate. Therefore, OXT may be increasing the salience and reward value of anticipated social feedback. In the PLC group, response times and state anxiety scores during social feedback were associated with signal changes in these same regions but not in the OXT group. OXT may therefore have also facilitated learning by reducing anxiety in the social feedback condition. Overall our results provide the first evidence for cultural differences in social facilitation of learning per se, but a similar selective enhancement of learning with social feedback under OXT. This effect of OXT may be associated with enhanced responses and functional connectivity in emotional memory and reward processing regions. © 2015 Wiley Periodicals, Inc.

Artemisinin and Artemisia annua leaves alleviate Eimeria tenella infection by facilitating apoptosis of host cells and suppressing inflammatory response.

PubMed

Jiao, JinYing; Yang, YunQiao; Liu, MingJiang; Li, JinGui; Cui, Yi; Yin, ShaoJie; Tao, JianPing

2018-04-30

Evasion strategies of intracellular parasites by hijacking cellular pathways, are necessary to ensure successful survival and replication. Eimeria tenella (E. tenella) has the ability to circumvent apoptosis of infected cells through increased expression of the transcriptional factor NF-κB and the anti-apoptotic factor Bcl-x L during the development of second generation schizonts. Artemisinin (ART) and its original plant, the dried leaves of Artemisia annua (LAA) have been shown to be effective against avian coccidiosis, however, the underlying mechanism remains unclear. We showed that E. tenella infection promoted the expression of anti-apoptotic protein Bcl-2 and inhibited the expression of pro-apoptotic proteins Bax and cleaved caspase-3 at 60 h post infection (PI), with a higher ratio of Bcl-2 to Bax. Nevertheless, the expression trends of Bcl-2, Bax and caspase-3 were reversed at 120 h and 192 h PI. ART treatment significantly abrogated Bcl-2 expression, whereas it promoted the expression levels of Bax and cleaved caspase-3 at the three time points above. Additionally, ART remarkably suppressed the increased mRNA expressions of NF-κB and interleukin-17A in ceca during infection by E. tenella. Compared with the ART treatment, LAA treatment exerted more improvements in clinical symptoms, promoting apoptosis and suppressing inflammatory response. These alterations caused by ART and LAA treatments were consistent with the reduced clinical diarrhea and pathological improvements in chicken ceca. Collectively, these results indicate that the inhibitory effects of ART or LAA on E. tenella infection may work through facilitating the apoptosis of infected host cells and inhibiting the inflammatory response. Copyright © 2018 Elsevier B.V. All rights reserved.

Facilitating Dialogues about Racial Realities

ERIC Educational Resources Information Center

Quaye, Stephen John

2014-01-01

Background/Context: Facilitating dialogues about racial issues in higher education classroom settings continues to be a vexing problem facing postsecondary educators. In order for students to discuss race with their peers, they need skilled facilitators who are knowledgeable about racial issues and able to support students in these difficult…

The Essential Elements of Facilitation.

ERIC Educational Resources Information Center

Priest, Simon; Gass, Michael; Gillis, Lee

Most organizations find it difficult to implement change, and only about 10 percent of learning from training and development experiences is actually applied in the workplace. This book advocates facilitation as a means of enhancing change and increasing productivity. Facilitation engages employees by enhancing the processes associated with their…

Spinal gap junctions: potential involvement in pain facilitation.

PubMed

Spataro, Leah E; Sloane, Evan M; Milligan, Erin D; Wieseler-Frank, Julie; Schoeniger, Diana; Jekich, Brian M; Barrientos, Ruth M; Maier, Steven F; Watkins, Linda R

2004-09-01

Glia are now recognized as important contributors in pathological pain creation and maintenance. Spinal cord glia exhibit extensive gap junctional connectivity, raising the possibility that glia are involved in the contralateral spread of excitation resulting in mirror image pain. In the present experiments, the gap junction decoupler carbenoxolone was administered intrathecally after induction of neuropathic pain in response to sciatic nerve inflammation (sciatic inflammatory neuropathy) or partial nerve injury (chronic constriction injury). In both neuropathic pain models, a low dose of carbenoxolone reversed mirror image mechanical allodynia, while leaving ipsilateral mechanical allodynia unaffected. Ipsilateral thermal hyperalgesia was briefly attenuated. Critically, blockade of mechanical allodynia and thermal hyperalgesia was not observed in response to intrathecal glycyrrhizic acid, a compound similar to carbenoxolone in all respects but it does not decouple gap junctions. Thus, blockade of mechanical allodynia and thermal hyperalgesia by carbenoxolone does appear to reflect an effect on gap junctions. Examination of carbenoxolone's effects on intrathecal human immunodeficiency virus type 1 gp120 showed that blockade of pain facilitation might result, at least in part, via suppression of interleukin-1 and, in turn, interleukin-6. These data provide the first suggestion that spread of excitation via gap junctions might contribute importantly to inflammatory and traumatic neuropathic pain. The current studies provide evidence for involvement of gap junctions in spinal cord pain facilitation. Intrathecal carbenoxolone, a gap junction decoupler, reversed neuropathy-induced mirror image pain and intrathecal gp120-induced allodynia. In addition, it decreased gp120-induced proinflammatory cytokines. This suggests gap junction activation might lead to proinflammatory cytokine release by distantly activated glia.

Single-trial decoding of auditory novelty responses facilitates the detection of residual consciousness

PubMed Central

King, J.R.; Faugeras, F.; Gramfort, A.; Schurger, A.; El Karoui, I.; Sitt, J.D.; Rohaut, B.; Wacongne, C.; Labyt, E.; Bekinschtein, T.; Cohen, L.; Naccache, L.; Dehaene, S.

2017-01-01

Detecting residual consciousness in unresponsive patients is a major clinical concern and a challenge for theoretical neuroscience. To tackle this issue, we recently designed a paradigm that dissociates two electro-encephalographic (EEG) responses to auditory novelty. Whereas a local change in pitch automatically elicits a mismatch negativity (MMN), a change in global sound sequence leads to a late P300b response. The latter component is thought to be present only when subjects consciously perceive the global novelty. Unfortunately, it can be difficult to detect because individual variability is high, especially in clinical recordings. Here, we show that multivariate pattern classifiers can extract subject-specific EEG patterns and predict single-trial local or global novelty responses. We first validate our method with 38 high-density EEG, MEG and intracranial EEG recordings. We empirically demonstrate that our approach circumvents the issues associated with multiple comparisons and individual variability while improving the statistics. Moreover, we confirm in control subjects that local responses are robust to distraction whereas global responses depend on attention. We then investigate 104 vegetative state (VS), minimally conscious state (MCS) and conscious state (CS) patients recorded with high-density EEG. For the local response, the proportion of significant decoding scores (M = 60%) does not vary with the state of consciousness. By contrast, for the global response, only 14% of the VS patients' EEG recordings presented a significant effect, compared to 31% in MCS patients' and 52% in CS patients'. In conclusion, single-trial multivariate decoding of novelty responses provides valuable information in non-communicating patients and paves the way towards real-time monitoring of the state of consciousness. PMID:23859924

Uses of self-regulation to facilitate and restrain addictive behavior.

PubMed

Baumeister, Roy F; Vonasch, Andrew J

2015-05-01

We apply self-regulation theory to understand addictive behavior. Self-regulation and volition depend on a limited resource, and when that resource has been depleted, self-regulation becomes prone to fail. Moving beyond traditional models that have emphasized the relevance of self-regulation to quitting addiction, we propose that self-regulation is used both to facilitate and resist addictive behaviors. Self-regulation is often needed to overcome initial aversion to drugs and alcohol, as well as to maintain addictive usage patterns despite situational obstacles (e.g., illegality, erratic availability, family disapproval). Sustaining addiction also requires preventing use from spiraling out of control and interfering with other aspects of life. More generally, the automaticity and irresistibility of addictive responses may have been overrated, as indicated by how addictive behaviors respond rationally to incentives and other concerns. Self-regulation does facilitate quitting, and relapse may be especially likely when self-regulatory capabilities are depleted. Copyright © 2014 Elsevier Ltd. All rights reserved.

Students as facilitators in a teacher training program: motivation for leadership roles.

PubMed

Burgess, Annette; van Diggele, Christie; Mellis, Craig

2015-01-01

Although students often partake in peer-teaching activities during medical school, they are rarely provided with formal training in teaching. We have previously described our teacher training (TT) program for medical students. The TT program is delivered face-to-face across two sessions. In order to alleviate academic teaching load required to run the course, and at the same time provide our final-year students with practical opportunities to develop their leadership skills, we engaged five senior students as co-facilitators alongside academic staff. By developing an understanding of our students' motivation to participate as facilitators, we may be able to promote an interest within leadership in teaching among other students. Our study sought to examine students' motivation to take part as facilitators in the TT program. Data were collected through a focus group session with the five student facilitators. Self-determination theory, which poses that there are three elements key to intrinsic motivation, including autonomy, competence, and relatedness, was used as a conceptual lens to identify and code recurrent themes in the data. Elements that motivated students to assist in facilitation included an opportunity to review and build on their knowledge and skills in teaching practices; the recognition and acknowledgement received from school staff and fellow students; the opportunity to develop these relationships; and a desire to increase their peer-teaching responsibilities. By actively involving our students in leadership practices, we were able to not only engage the students, but also develop our student community and contribute to the promotion of a culture of excellence in teaching within the hospital.

Facilitated early cortical processing of nude human bodies.

PubMed

Alho, Jussi; Salminen, Nelli; Sams, Mikko; Hietanen, Jari K; Nummenmaa, Lauri

2015-07-01

Functional brain imaging has identified specialized neural systems supporting human body perception. Responses to nude vs. clothed bodies within this system are amplified. However, it remains unresolved whether nude and clothed bodies are processed by same cerebral networks or whether processing of nude bodies recruits additional affective and arousal processing areas. We recorded simultaneous MEG and EEG while participants viewed photographs of clothed and nude bodies. Global field power revealed a peak ∼145ms after stimulus onset to both clothed and nude bodies, and ∼205ms exclusively to nude bodies. Nude-body-sensitive responses were centered first (100-200ms) in the extrastriate and fusiform body areas, and subsequently (200-300ms) in affective-motivational areas including insula and anterior cingulate cortex. We conclude that visibility of sexual features facilitates early cortical processing of human bodies, the purpose of which is presumably to trigger sexual behavior and ultimately ensure reproduction. Copyright © 2015 Elsevier B.V. All rights reserved.

School Administrator Perceptions of Cyberbullying Facilitators and Barriers to Preventive Action: A Qualitative Study

ERIC Educational Resources Information Center

Young, Rachel; Tully, Melissa; Ramirez, Marizen

2017-01-01

Background: Schools are often held responsible for preventing or addressing cyberbullying, yet little is known about school administrator perceptions of cyberbullying and the challenges they face in addressing this public health issue. Aims: The goal of this study is to examine school administrators' perceptions of the facilitators of…

Electron beam energy stabilization using a neural network hybrid controller at the Australian Synchrotron Linac.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meier, E.; Morgan, M. J.; Biedron, S. G.

2009-01-01

This paper describes the implementation of a neural network hybrid controller for energy stabilization at the Australian Synchrotron Linac. The structure of the controller consists of a neural network (NNET) feed forward control, augmented by a conventional Proportional-Integral (PI) feedback controller to ensure stability of the system. The system is provided with past states of the machine in order to predict its future state, and therefore apply appropriate feed forward control. The NNET is able to cancel multiple frequency jitter in real-time. When it is not performing optimally due to jitter changes, the system can successfully be augmented by themore » PI controller to attenuate the remaining perturbations. With a view to control the energy and bunch length at the FERMI{at}Elettra Free Electron Laser (FEL), the present study considers a neural network hybrid feed forward-feedback type of control to rectify limitations related to feedback systems, such as poor response for high jitter frequencies or limited bandwidth, while ensuring robustness of control. The Australian Synchrotron Linac is equipped with a beam position monitor (BPM), that was provided by Sincrotrone Trieste from a former transport line thus allowing energy measurements and energy control experiments. The present study will consequently focus on correcting energy jitter induced by variations in klystron phase and voltage.« less

Incongruent Abstract Stimulus-Response Bindings Result in Response Interference: fMRI and EEG Evidence from Visual Object Classification Priming

ERIC Educational Resources Information Center

Horner, Aidan J.; Henson, Richard N.

2012-01-01

Stimulus repetition often leads to facilitated processing, resulting in neural decreases (repetition suppression) and faster RTs (repetition priming). Such repetition-related effects have been attributed to the facilitation of repeated cognitive processes and/or the retrieval of previously encoded stimulus-response (S-R) bindings. Although…

Controlling public speaking jitters: making the butterflies fly in formation.

PubMed

Harvey, Hannah; Baum, Neil

2014-01-01

Nearly every person who has been asked to give a speech or who has volunteered to make a presentation to a group of strangers develops fear and anxiety prior to the presentation. Most of us, the authors included, start hyperventilating, our pulse quickens, and we feel a little weak in the knees. We grab the lectern and our knuckles turn white as we hold on for dear life. This is a normal response that everyone experiences. However, this stress can be controlled and made manageable by understanding the stress response cycle and practicing a few techniques that calm those butterflies flying around in the pit of your stomach.

Facilitating the implementation of clinical technology in healthcare: what role does a national agency play?

PubMed

Harvey, Gill; Llewellyn, Sue; Maniatopoulos, Greg; Boyd, Alan; Procter, Rob

2018-05-10

Accelerating the implementation of new technology in healthcare is typically complex and multi-faceted. One strategy is to charge a national agency with the responsibility for facilitating implementation. This study examines the role of such an agency in the English National Health Service. In particular, it compares two different facilitation strategies employed by the agency to support the implementation of insulin pump therapy. The research involved an empirical case study of four healthcare organisations receiving different levels of facilitation from the national agency: two received active hands-on facilitation; one was the intended recipient of a more passive, web-based facilitation strategy; the other implemented the technology without any external facilitation. The primary method of data collection was semi-structured qualitative interviews with key individuals involved in implementation. The integrated-PARIHS framework was applied as a conceptual lens to analyse the data. The two sites that received active facilitation from an Implementation Manager in the national agency made positive progress in implementing the technology. In both sites there was a high level of initial receptiveness to implementation. This was similar to a site that had successfully introduced insulin pump therapy without facilitation support from the national agency. By contrast, a site that did not have direct contact with the national agency made little progress with implementation, despite the availability of a web-based implementation resource. Clinicians expressed differences of opinion around the value and effectiveness of the technology and contextual barriers related to funding for implementation persisted. The national agency's intended roll out strategy using passive web-based facilitation appeared to have little impact. When favourable conditions exist, in terms of agreement around the value of the technology, clinician receptiveness and motivation to change, active

From parent to 'peer facilitator': a qualitative study of a peer-led parenting programme.

PubMed

Thomson, S; Michelson, D; Day, C

2015-01-01

Peer-led interventions are increasingly common in community health settings. Although peer-led approaches have proven benefits for service users, relatively little is known about the process and outcomes of participation for peer leaders. This study investigated experiences of parents who had participated as 'peer facilitators' in Empowering Parents, Empowering Communities (EPEC), a peer-led programme designed to improve access to evidence-based parenting support in socially disadvantaged communities. A qualitative cross-sectional design was used. Semi-structured interviews were conducted with 14 peer facilitators and scrutinized using thematic analysis. Peer facilitators developed their knowledge and skills through personal experience of receiving parenting support, participation in formal training and supervised practice, access to an intervention manual, and peer modelling. Peer facilitators described positive changes in their own families, confidence and social status. Transformative personal gains reinforced peer facilitators' role commitment and contributed to a cohesive 'family' identity among EPEC staff and service users. Peer facilitators' enthusiasm, openness and mutual identification with families were seen as critical to EPEC's effectiveness and sustainability. Peer facilitators also found the training emotionally and intellectually demanding. There were particular difficulties around logistical issues (e.g. finding convenient supervision times), managing psychosocial complexity and child safeguarding. The successful delivery and sustained implementation of peer-led interventions requires careful attention to the personal qualities and support of peer leaders. Based on the findings of this study, support should include training, access to intervention manuals, regular and responsive supervision, and logistical/administrative assistance. Further research is required to elaborate and extend these findings to other peer-led programmes. © 2014 John Wiley

Stimuli-Responsive Polymeric Nanoparticles.

PubMed

Liu, Xiaolin; Yang, Ying; Urban, Marek W

2017-07-01

There is increasing evidence that stimuli-responsive nanomaterials have become significantly critical components of modern materials design and technological developments. Recent advances in synthesis and fabrication of stimuli-responsive polymeric nanoparticles with built-in stimuli-responsive components (Part A) and surface modifications of functional nanoparticles that facilitate responsiveness (Part B) are outlined here. The synthesis and construction of stimuli-responsive spherical, core-shell, concentric, hollow, Janus, gibbous/inverse gibbous, and cocklebur morphologies are discussed in Part A, with the focus on shape, color, or size changes resulting from external stimuli. Although inorganic/metallic nanoparticles exhibit many useful properties, including thermal or electrical conductivity, catalytic activity, or magnetic properties, their assemblies and formation of higher order constructs are often enhanced by surface modifications. Section B focuses on selected surface reactions that lead to responsiveness achieved by decorating nanoparticles with stimuli-responsive polymers. Although grafting-to and grafting-from dominate these synthetic efforts, there are opportunities for developing novel synthetic approaches facilitating controllable recognition, signaling, or sequential responses. Many nanotechnologies utilize a combination of organic and inorganic phases to produce ceramic or metallic nanoparticles. One can envision the development of new properties by combining inorganic (metals, metal oxides) and organic (polymer) phases into one nanoparticle designated as "ceramers" (inorganics) and "metamers" (metallic). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Following a natural experiment of guideline adaptation and early implementation: a mixed-methods study of facilitation

PubMed Central

2012-01-01

Background Facilitation is emerging as an important strategy in the uptake of evidence. However, it is not entirely clear from a practical perspective how facilitation occurs to help move research evidence into nursing practice. The Canadian Partnership Against Cancer, also known as the 'Partnership,' is a Pan-Canadian initiative supporting knowledge translation activity for improved care through guideline use. In this case-series study, five self-identified groups volunteered to use a systematic methodology to adapt existing clinical practice guidelines for Canadian use. With 'Partnership' support, local and external facilitators provided assistance for groups to begin the process by adapting the guidelines and planning for implementation. Methods To gain a more comprehensive understanding of the nature of facilitation, we conducted a mixed-methods study. Specifically, we examined the role and skills of individuals actively engaged in facilitation as well as the actual facilitation activities occurring within the 'Partnership.' The study was driven by and builds upon a focused literature review published in 2010 that examined facilitation as a role and process in achieving evidence-based practice in nursing. An audit tool outlining 46 discrete facilitation activities based on results of this review was used to examine the facilitation noted in the documents (emails, meeting minutes, field notes) of three nursing-related cases participating in the 'Partnership' case-series study. To further examine the concept, six facilitators were interviewed about their practical experiences. The case-audit data were analyzed through a simple content analysis and triangulated with participant responses from the focus group interview to understand what occurred as these cases undertook guideline adaptation. Results The analysis of the three cases revealed that almost all of the 46 discrete, practical facilitation activities from the literature were evidenced. Additionally, case

RING finger and WD repeat domain 3 (RFWD3) associates with replication protein A (RPA) and facilitates RPA-mediated DNA damage response.

PubMed

Liu, Shangfeng; Chu, Jessica; Yucer, Nur; Leng, Mei; Wang, Shih-Ya; Chen, Benjamin P C; Hittelman, Walter N; Wang, Yi

2011-06-24

DNA damage response is crucial for maintaining genomic integrity and preventing cancer by coordinating the activation of checkpoints and the repair of damaged DNA. Central to DNA damage response are the two checkpoint kinases ATM and ATR that phosphorylate a wide range of substrates. RING finger and WD repeat domain 3 (RFWD3) was initially identified as a substrate of ATM/ATR from a proteomic screen. Subsequent studies showed that RFWD3 is an E3 ubiquitin ligase that ubiquitinates p53 in vitro and positively regulates p53 levels in response to DNA damage. We report here that RFWD3 associates with replication protein A (RPA), a single-stranded DNA-binding protein that plays essential roles in DNA replication, recombination, and repair. Binding of RPA to single-stranded DNA (ssDNA), which is generated by DNA damage and repair, is essential for the recruitment of DNA repair factors to damaged sites and the activation of checkpoint signaling. We show that RFWD3 is physically associated with RPA and rapidly localizes to sites of DNA damage in a RPA-dependent manner. In vitro experiments suggest that the C terminus of RFWD3, which encompass the coiled-coil domain and the WD40 domain, is necessary for binding to RPA. Furthermore, DNA damage-induced phosphorylation of RPA and RFWD3 is dependent upon each other. Consequently, loss of RFWD3 results in the persistent foci of DNA damage marker γH2AX and the repair protein Rad51 in damaged cells. These findings suggest that RFWD3 is recruited to sites of DNA damage and facilitates RPA-mediated DNA damage signaling and repair.

Oligonucleotide facilitators may inhibit or activate a hammerhead ribozyme.

PubMed Central

Jankowsky, E; Schwenzer, B

1996-01-01

Facilitators are oligonucleotides capable of affecting hammerhead ribozyme activity by interacting with the substrate at the termini of the ribozyme. Facilitator effects were determined in vitro using a system consisting of a ribozyme with 7 nucleotides in every stem sequence and two substrates with inverted facilitator binding sequences. The effects of 9mer and 12mer RNA as well as DNA facilitators which bind either adjacent to the 3'- or 5'-end of the ribozyme were investigated. A kinetic model was developed which allows determination of the apparent dissociation constant of the ribozyme-substrate complex from single turnover reactions. We observed a decreased dissociation constant of the ribozyme-substrate complex due to facilitator addition corresponding to an additional stabilization energy of delta delta G=-1.7 kcal/mol with 3'-end facilitators. The cleavage rate constant was increased by 3'-end facilitators and decreased by 5'-end facilitators. Values for Km were slightly lowered by all facilitators and kcat was increased by 3'-end facilitators and decreased by 5'-end facilitators in our system. Generally the facilitator effects increased with the length of the facilitators and RNA provided greater effects than DNA of the same sequence. Results suggest facilitator influences on several steps of the hammerhead reaction, substrate association, cleavage and dissociation of products. Moreover, these effects are dependent in different manners on ribozyme and substrate concentration. This leads to the conclusion that there is a concentration dependence whether activation or inhibition is caused by facilitators. Conclusions are drawn with regard to the design of hammerhead ribozyme facilitator systems. PMID:8602353

Facilitation of contrast detection in near-peripheral vision.

PubMed

Giorgi, Robert G; Soong, Grace P; Woods, Russell L; Peli, Eli

2004-12-01

Foveal detection of a Gabor patch (target) is facilitated by collinear, displaced high-contrast flankers. Polat and Sagi reported that the same phenomenon occurred in the periphery, but no data were presented [Proc. Natl. Acad. Sci. 91 (1994) 1206]. Others have found no facilitation in a limited number of conditions tested. To resolve this apparent conflict, we measured lateral facilitation in the near-periphery using a range of stimulus parameters. We found facilitation for a range of target-flanker distances for peripheral eccentricities up to 6 degrees , but the magnitude of the effect was less than found in central vision. Facilitation varied across subjects and with spatial frequency. Flanker contrast had no effect over the range evaluated (10-80%). Equal facilitation was found for two global arrangements of the stimulus pattern. Facilitation was found using a temporal, but not a spatial two-alternative forced-choice paradigm, accounting for the different results among previous studies. This finding supports previous indications of the role of attention in altering such facilitation. The value of facilitation from lateral interactions for persons with central vision impairment, who have to shift their attention to a peripheral locus constantly, needs to be examined.

Physician perspectives on a tailored multifaceted primary care practice facilitation intervention for improvement of cardiovascular care.

PubMed

Liddy, Clare; Singh, Jatinderpreet; Guo, Merry; Hogg, William

2016-02-01

Practice facilitation is an effective way to help physicians implement change in their clinics, but little is known about physicians' perspectives on this service. To examine physicians' responses to a practice facilitation program, focussing on their overall satisfaction, perceived most significant clinical changes, and interactions with the facilitator. The Improved Delivery of Cardiovascular Care program investigated the impact of practice facilitation on improving the quality of cardiovascular primary care in Eastern Ontario, Canada, from 2007 to 2011. We conducted a qualitative content analysis of post-intervention surveys completed by participating physicians, using a constant comparison approach framed around the Chronic Care Model. Ninety-five physicians completed the survey. Physicians overwhelmingly viewed the program positively, though descriptions of its benefits and impact varied widely. Facilitators filled three key roles for physicians, acting as a resource centre, motivator and outside perspective. Physicians adopted a number of changes in their practices. These changes include adoption of clinical information systems (diabetes registries), decision support tools (chart audits, guideline documents, flow sheets) and delivery system design (community resources). Most physicians appreciated having access to a practice facilitator and viewed the intervention positively. Insight into physicians' perspectives on practice facilitation provides a valuable counterpoint to outcomes-based evaluations of such services. Further research should investigate potential obstacles in the group of physicians who make fewer practice changes, as well as the sustainability of this type of facilitation intervention. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

5-HT4 receptors facilitate cholinergic neurotransmission throughout the murine gastrointestinal tract.

PubMed

Pauwelyn, V; Lefebvre, R A

2017-08-01

In the gastrointestinal tract of several species, facilitating 5-HT 4 receptors were proposed on myenteric cholinergic neurons innervating smooth muscle by in vitro study of the effect of the selective 5-HT 4 receptor agonist prucalopride on submaximal cholinergic contractions. This was not yet established in the murine gastrointestinal tract. In circular smooth muscle strips from murine fundus, jejunum and colon, contractions were induced by electrical field stimulation in the presence of guanethidine, L-NAME and for colon also MRS 2500. Submaximal contractions were induced to study the influence of prucalopride. Electrical field stimulation at reduced voltage induced reproducible submaximal neurogenic and cholinergic contractions as the contractions were abolished by tetrodotoxin and atropine. Hexamethonium had no systematic inhibitory effect but mecamylamine reduced the responses, suggesting that part of the cholinergic response is due to activation of preganglionic neurons. Prucalopride concentration-dependently increased the submaximal cholinergic contractions in the three tissue types, reaching maximum from 0.03 μmol/L onwards. The facilitation in the different series with 0.03 μmol/L prucalopride ranged from 41% to 104%, 30% to 76% and 24% to 74% in fundus, jejunum, and colon, respectively. The effect of 0.03 μmol/L prucalopride was concentration-dependently inhibited by GR 113808. In the murine gastrointestinal tract, activation of 5-HT 4 receptors with prucalopride enhances cholinergic contractions, illustrating facilitation of myenteric cholinergic neurotransmission. The degree of enhancement with prucalopride is of similar magnitude as previously reported in other species, but the effective concentrations are lower than those needed in the gastrointestinal tract of other species. © 2017 John Wiley & Sons Ltd.

The coral immune response facilitates protection against microbes during tissue regeneration.

PubMed

van de Water, Jeroen A J M; Ainsworth, Tracy D; Leggat, William; Bourne, David G; Willis, Bette L; van Oppen, Madeleine J H

2015-07-01

Increasing physical damage on coral reefs from predation, storms and anthropogenic disturbances highlights the need to understand the impact of injury on the coral immune system. In this study, we examined the regulation of the coral immune response over 10 days following physical trauma artificially inflicted on in situ colonies of the coral Acropora aspera, simultaneously with bacterial colonization of the lesions. Corals responded to injury by increasing the expression of immune system-related genes involved in the Toll-like and NOD-like receptor signalling pathways and the lectin-complement system in three phases (<2, 4 and 10 days post-injury). Phenoloxidase activity was also significantly upregulated in two phases (<3 and 10 days post-injury), as were levels of non-fluorescent chromoprotein. In addition, green fluorescent protein expression was upregulated in response to injury from 4 days post-injury, while cyan fluorescent protein expression was reduced. No shifts in the composition of coral-associated bacterial communities were evident following injury based on 16S rRNA gene amplicon pyrosequencing. Bacteria-specific fluorescence in situ hybridization also showed no evidence of bacterial colonization of the wound or regenerating tissues. Coral tissues showed near-complete regeneration of lesions within 10 days. This study demonstrates that corals exhibit immune responses that support rapid recovery following physical injury, maintain coral microbial homeostasis and prevent bacterial infestation that may compromise coral fitness. © 2015 John Wiley & Sons Ltd.

Automatic Semantic Facilitation in Anterior Temporal Cortex Revealed through Multimodal Neuroimaging

PubMed Central

Gramfort, Alexandre; Hämäläinen, Matti S.; Kuperberg, Gina R.

2013-01-01

A core property of human semantic processing is the rapid, facilitatory influence of prior input on extracting the meaning of what comes next, even under conditions of minimal awareness. Previous work has shown a number of neurophysiological indices of this facilitation, but the mapping between time course and localization—critical for separating automatic semantic facilitation from other mechanisms—has thus far been unclear. In the current study, we used a multimodal imaging approach to isolate early, bottom-up effects of context on semantic memory, acquiring a combination of electroencephalography (EEG), magnetoencephalography (MEG), and functional magnetic resonance imaging (fMRI) measurements in the same individuals with a masked semantic priming paradigm. Across techniques, the results provide a strikingly convergent picture of early automatic semantic facilitation. Event-related potentials demonstrated early sensitivity to semantic association between 300 and 500 ms; MEG localized the differential neural response within this time window to the left anterior temporal cortex, and fMRI localized the effect more precisely to the left anterior superior temporal gyrus, a region previously implicated in semantic associative processing. However, fMRI diverged from early EEG/MEG measures in revealing semantic enhancement effects within frontal and parietal regions, perhaps reflecting downstream attempts to consciously access the semantic features of the masked prime. Together, these results provide strong evidence that automatic associative semantic facilitation is realized as reduced activity within the left anterior superior temporal cortex between 300 and 500 ms after a word is presented, and emphasize the importance of multimodal neuroimaging approaches in distinguishing the contributions of multiple regions to semantic processing. PMID:24155321

What facilitates the entry of persons with disabilities into South African companies?

PubMed

Wiggett-Barnard, Cindy; Swartz, Leslie

2012-01-01

The persistent high unemployment rate for persons with disabilities (PWDs) is a world-wide concern. The aim of this research was to identify facilitating factors for the entry of PWDs into the labour market. A survey of Human Resources (HR) managers in South African (SA) companies was conducted to explore what would assist with hiring PWDs. The sample population of companies was identified through the Marketline Library database and supplemented with all Johannesburg Stock Exchange companies. This rendered a population size of 348. A response rate of 25% (86) was achieved. Companies that have appointed PWDs in the past seem more willing to appoint PWDs in the future. Companies value information on accommodation (preparation of the environment and cost) and the impact of disability on job performance most. The use of specialised recruitment agencies, the development of targeted recruitment plans and staff sensitisation training, as well as internships are perceived as the best facilitators for the employment of PWDs. Rehabilitation practitioners can inform PWDs on the best strategies for approaching companies. Companies with facilitating factors already in place may also be more willing to employ PWDs and rehabilitation practitioners can target these companies as future employers of PWDs.

Investigation of a solid state power combining antenna proposed for use in the solar power satellite

NASA Technical Reports Server (NTRS)

Farmer, L. A.

1981-01-01

Performance tests performed on a four-feed microstrip antenna and feed network are analyzed. Frequency response with and without amplifiers, an investigation of noise threshold, phase tracking, and jitter are included. Recommendations for further development of SPS power conversion modules are also included.

Facilitating The Medical Response Into An Active Shooter Hot Zone

DTIC Science & Technology

2016-06-01

before receiving care because most jurisdictions have a policy in place that stipulates emergency medical services ( EMS ) wait to enter a scene until law...people who most need it, and consequently, there can be a greater loss of life. How can a combined LE and EMS response, based on combat medical care... EMS entry teams, will provide better patient viability prior to hospital care. This will not be a critique of right and wrong, as the responders did

Research, Development, and Validation of a School Leader's Resource Guide for the Facilitation of Social Media Use by School Staff

ERIC Educational Resources Information Center

Gooch, Deanna L.

2012-01-01

Many school leaders do not understand their rights and responsibilities to facilitate social media use by their staff in P-12 education. This dissertation was designed to research, develop, and validate a resource guide school leaders can use to facilitate social media use by school staff. "Research, Development, and Validation of a School…

Facilitative glucose transporter gene expression in human lymphocytes, monocytes, and macrophages: a role for GLUT isoforms 1, 3, and 5 in the immune response and foam cell formation.

PubMed

Fu, Yuchang; Maianu, Lidia; Melbert, Barry R; Garvey, W Timothy

2004-01-01

Cellular glucose uptake is mediated by a family of facilitative glucose transporters (GLUT) exhibiting differences in kinetics, substrate specificity, and tissue-specific expression. GLUT isoform expression has not been comprehensively studied in human leukocytes, which participate in immune and inflammatory responses and are critical for host defense. Therefore, we studied the regulated expression of GLUT 1-5 mRNA and protein in isolated human lymphocytes and monocytes and in human THP-1 macrophages and foam cells. Lymphocytes expressed GLUT 1 and GLUT 3 proteins, and cellular levels of both isoforms were augmented 3.5- to 6-fold following activation by phytohemagglutinin (PHA). Monocytes expressed 8.4-fold more GLUT 3 protein and 88% less GLUT 1 than lymphocytes, and activation by lipopolysaccharide (LPS) led to a 1.9-fold increase in GLUT 1. At the level of mRNA expression, GLUT 3 mRNA was the most prevalent GLUT mRNA species in monocytes, while lymphocytes expressed equal numbers of GLUT 1 and GLUT 3 transcripts. Differentiation of THP-1 monocytes into macrophages was associated with marked induction of GLUT 3 and GLUT 5 protein expression, and high levels of GLUT 1, GLUT 3, and GLUT 5 were maintained after transformation to foam cells. GLUT 5 mRNA was expressed in 2-fold greater abundance in macrophages and foam cells than that observed for GLUT 1 mRNA, while the level of GLUT 3 mRNA was intermediate. This facilitative glucose transporters are differentially expressed and regulated in human leukocytes in a pattern that could facilitate cellular functions. Speculatively, high GLUT 1 and GLUT 3 expression could provide cellular fuel for the immune response, and high levels of high-affinity GLUT 3 in macrophages might allow the cell to compete with pathogens for hexoses, even in the presence of low interstitial glucose concentrations. Ample expression of GLUT 1 and GLUT 3 in foam cells could also provide hexose substrates and promote lipid loading. The role for

The shift from plant-plant facilitation to competition under severe water deficit is spatially explicit.

PubMed

O'Brien, Michael J; Pugnaire, Francisco I; Armas, Cristina; Rodríguez-Echeverría, Susana; Schöb, Christian

2017-04-01

The stress-gradient hypothesis predicts a higher frequency of facilitative interactions as resource limitation increases. Under severe resource limitation, it has been suggested that facilitation may revert to competition, and identifying the presence as well as determining the magnitude of this shift is important for predicting the effect of climate change on biodiversity and plant community dynamics. In this study, we perform a meta-analysis to compare temporal differences of species diversity and productivity under a nurse plant ( Retama sphaerocarpa ) with varying annual rainfall quantity to test the effect of water limitation on facilitation. Furthermore, we assess spatial differences in the herbaceous community under nurse plants in situ during a year with below-average rainfall. We found evidence that severe rainfall deficit reduced species diversity and plant productivity under nurse plants relative to open areas. Our results indicate that the switch from facilitation to competition in response to rainfall quantity is nonlinear. The magnitude of this switch depended on the aspect around the nurse plant. Hotter south aspects under nurse plants resulted in negative effects on beneficiary species, while the north aspect still showed facilitation. Combined, these results emphasize the importance of spatial heterogeneity under nurse plants for mediating species loss under reduced precipitation, as predicted by future climate change scenarios. However, the decreased water availability expected under climate change will likely reduce overall facilitation and limit the role of nurse plants as refugia, amplifying biodiversity loss.

Technologies and Techniques for Supporting Facilitated Video

ERIC Educational Resources Information Center

Linnell, Natalie

2011-01-01

Worldwide, demand for education of all kinds is increasing beyond the capacity to provide it. One approach that shows potential for addressing this demand is facilitated video. In facilitated video, an educator is recorded teaching, and that video is sent to a remote site where it is shown to students by a facilitator who creates interaction…

Transducer model produces facilitation from opposite-sign flanks

NASA Technical Reports Server (NTRS)

Solomon, J. A.; Watson, A. B.; Morgan, M. J.

1999-01-01

Small spots, lines and Gabor patterns can be easier to detect when they are superimposed upon similar spots, lines and Gabor patterns. Traditionally, such facilitation has been understood to be a consequence of nonlinear contrast transduction. Facilitation has also been reported to arise from non-overlapping patterns with opposite sign. We point out that this result does not preclude the traditional explanation for superimposed targets. Moreover, we find that facilitation from opposite-sign flanks is weaker than facilitation from same-sign flanks. Simulations with a transducer model produce opposite-sign facilitation.

Emotional words facilitate lexical but not early visual processing.

PubMed

Trauer, Sophie M; Kotz, Sonja A; Müller, Matthias M

2015-12-12

Emotional scenes and faces have shown to capture and bind visual resources at early sensory processing stages, i.e. in early visual cortex. However, emotional words have led to mixed results. In the current study ERPs were assessed simultaneously with steady-state visual evoked potentials (SSVEPs) to measure attention effects on early visual activity in emotional word processing. Neutral and negative words were flickered at 12.14 Hz whilst participants performed a Lexical Decision Task. Emotional word content did not modulate the 12.14 Hz SSVEP amplitude, neither did word lexicality. However, emotional words affected the ERP. Negative compared to neutral words as well as words compared to pseudowords lead to enhanced deflections in the P2 time range indicative of lexico-semantic access. The N400 was reduced for negative compared to neutral words and enhanced for pseudowords compared to words indicating facilitated semantic processing of emotional words. LPC amplitudes reflected word lexicality and thus the task-relevant response. In line with previous ERP and imaging evidence, the present results indicate that written emotional words are facilitated in processing only subsequent to visual analysis.

Repetitive nerve stimulation and single-fiber electromyography in the evaluation of patients with suspected myasthenia gravis or Lambert-Eaton myasthenic syndrome: Review of recent literature.

PubMed

Chiou-Tan, Faye Y; Gilchrist, James M

2015-09-01

Our aim in this study was to provide an updated literature review of electrodiagnostic testing in myasthenia gravis and Lambert-Eaton myasthenic syndrome. A systematic review of the recent literature was performed using the following key words: myasthenia gravis (MG); Lambert-Eaton myasthenic syndrome (LEMS); electromyography (EMG); repetitive nerve stimulation (RNS); single-fiber electromyography (SFEMG); nerve conduction study; and normative values. Several articles supported testing of facial, bulbar, and respiratory muscles in the diagnosis of neuromuscular junction (NMJ) disorders, including muscle-specific kinase antibody (MuSK)-seropositive MG. Several articles supported use of concentric needle EMG as an alternative to SFEMG jitter in disorders of neuromuscular transmission. A limited number of articles addressed measurement of area (vs. amplitude) decrement in RNS and decreasing the threshold of post-exercise facilitation. Electrodiagnostic testing continues to be useful for diagnosis of MG and LEMS, although the quality of the evidence is not great. This literature review summarizes RNS and jitter measurement of facial and respiratory muscles and use of concentric needle EMG for SFEMG. © 2015 American Association of Neuromuscular and Electrodiagnostic Medicine.

Barriers and Facilitating Factors for Implementation of Genetic Services: A Public Health Perspective.

PubMed

Cornel, Martina C; van El, Carla G

2017-01-01

More than 15 years after the publication of the sequence of the human genome, the resulting changes in health care have been modest. At the same time, some promising examples in genetic services become visible, which contribute to the prevention of chronic disease such as cancer. These are discussed to identify barriers and facilitating factors for the implementation of genetic services. Examples from oncogenetics illustrate a high risk of serious disease where prevention is possible, especially in relatives. Some 5% of breast cancers and colorectal cancers are attributable to an inherited predisposition. These cancers occur at a relatively young age. DNA testing of relatives of affected patients may facilitate primary and secondary prevention. Training of non-genetic health care workers and health technology assessment are needed, as is translational research in terms of bringing genomics to health care practice while monitoring and evaluating. Stratified screening programs could include cascade screening and risk assessment based on family history. New roles and responsibilities will emerge. A clear assessment of the values implied is needed allowing to balance the pros and cons of interventions to further the responsible innovation of genetic services.

Facilitator training program: The Université Laval Interprofessional Initiative.

PubMed

Milot, Élise; Museux, Anne-Claire; Careau, Emmanuelle

2017-03-01

A facilitator training program (FTP) for interprofessional learning (IPL) facilitators has been developed at Université Laval. This article describes the impacts of this program as perceived by the 22 IPL facilitators involved and outlines recommendations. Two qualitative data collection strategies were used to document the facilitators' pedagogical needs and views of the program's impacts. Results suggest that the FTP's pedagogical approach was effective. The IPL facilitators became more aware of their challenges and identified concrete strategies to use. Training initiatives should equip IPL facilitators to cope with uncertainty, create a climate supporting active learning, and facilitate positive interactions between students.

Real-time multi-target ranging based on chaotic polarization laser radars in the drive-response VCSELs.

PubMed

Zhong, Dongzhou; Xu, Geliang; Luo, Wei; Xiao, Zhenzhen

2017-09-04

According to the principle of complete chaos synchronization and the theory of Hilbert phase transformation, we propose a novel real-time multi-target ranging scheme by using chaotic polarization laser radar in the drive-response vertical-cavity surface-emitting lasers (VCSELs). In the scheme, to ensure each polarization component (PC) of the master VCSEL (MVCSEL) to be synchronized steadily with that of the slave VCSEL, the output x-PC and y-PC from the MVCSEL in the drive system and those in the response system are modulated by the linear electro-optic effect simultaneously. Under this condition, by simulating the influences of some key parameters of the system on the synchronization quality and the relative errors of the two-target ranging, related operating parameters can be optimized. The x-PC and the y-PC, as two chaotic radar sources, are used to implement the real-time ranging for two targets. It is found that the measured distances of the two targets at arbitrary position exhibit strong real-time stability and only slight jitter. Their resolutions are up to millimeters, and their relative errors are very small and less than 2.7%.

Capture and playback synchronization in video conferencing

NASA Astrophysics Data System (ADS)

Shae, Zon-Yin; Chang, Pao-Chi; Chen, Mon-Song

1995-03-01

Packet-switching based video conferencing has emerged as one of the most important multimedia applications. Lip synchronization can be disrupted in the packet network as the result of the network properties: packet delay jitters at the capture end, network delay jitters, packet loss, packet arrived out of sequence, local clock mismatch, and video playback overlay with the graphic system. The synchronization problem become more demanding as the real time and multiparty requirement of the video conferencing application. Some of the above mentioned problem can be solved in the more advanced network architecture as ATM having promised. This paper will present some of the solutions to the problems that can be useful at the end station terminals in the massively deployed packet switching network today. The playback scheme in the end station will consist of two units: compression domain buffer management unit and the pixel domain buffer management unit. The pixel domain buffer management unit is responsible for removing the annoying frame shearing effect in the display. The compression domain buffer management unit is responsible for parsing the incoming packets for identifying the complete data blocks in the compressed data stream which can be decoded independently. The compression domain buffer management unit is also responsible for concealing the effects of clock mismatch, lip synchronization, and packet loss, out of sequence, and network jitters. This scheme can also be applied to the multiparty teleconferencing environment. Some of the schemes presented in this paper have been implemented in the Multiparty Multimedia Teleconferencing (MMT) system prototype at the IBM watson research center.

49 CFR 38.2 - Equivalent facilitation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 1 2010-10-01 2010-10-01 false Equivalent facilitation. 38.2 Section 38.2 Transportation Office of the Secretary of Transportation AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY SPECIFICATIONS FOR TRANSPORTATION VEHICLES General § 38.2 Equivalent facilitation. Departures from particular...

Facilitators and barriers to application of the Canadian C-spine rule by emergency department triage nurses.

PubMed

Clement, Catherine M; Stiell, Ian G; Lowe, Maureen A; Brehaut, Jamie C; Calder, Lisa A; Vaillancourt, Christian; Perry, Jeffrey J

2016-07-01

We recently conducted a multicentre implementation study on the use of the Canadian C-Spine Rule (CCR) by emergency department (ED) nurses to clear the c-spine in alert and stable trauma patients (n = 4506). The objective of this study was to conduct a survey of nurses, physicians, and administrators to evaluate their views on the facilitators and barriers to the implementation of the CCR. We conducted both a paper-based and an electronic survey of the three different ED hospital staff groups of nine large teaching hospitals in Ontario, including six regional trauma centres. The content of this survey was informed by a qualitative evaluation of the opinions of the study nurses who had participated in the validation study. 57.5% (281/489) ED triage nurses, 50.2% ED physicians, and 82.8% of administrators responded. Nurse responses most often showed support from manager/educators and teamwork between physicians, nurses, and managers as being important facilitators to the use of the CCR. Physician responses most often identified the importance of a nurse leader/champion/educator, and presence of strong physician leaders. Administrator responses indicated the importance of nurse educators/champions, nurse engagement, and educational support. Barriers indicated by all three groups included busy department, lack of physician support, and lack of nursing support. Bringing about change in clinical practice is complex. Strong leadership, effective communication, and senior physician buy-in appear to be very important. Identification of system-specific barriers and facilitators are important components of successful knowledge translation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Glacier Volume Change Estimation Using Time Series of Improved Aster Dems

NASA Astrophysics Data System (ADS)

Girod, Luc; Nuth, Christopher; Kääb, Andreas

2016-06-01

Volume change data is critical to the understanding of glacier response to climate change. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) system embarked on the Terra (EOS AM-1) satellite has been a unique source of systematic stereoscopic images covering the whole globe at 15m resolution and at a consistent quality for over 15 years. While satellite stereo sensors with significantly improved radiometric and spatial resolution are available to date, the potential of ASTER data lies in its long consistent time series that is unrivaled, though not fully exploited for change analysis due to lack of data accuracy and precision. Here, we developed an improved method for ASTER DEM generation and implemented it in the open source photogrammetric library and software suite MicMac. The method relies on the computation of a rational polynomial coefficients (RPC) model and the detection and correction of cross-track sensor jitter in order to compute DEMs. ASTER data are strongly affected by attitude jitter, mainly of approximately 4 km and 30 km wavelength, and improving the generation of ASTER DEMs requires removal of this effect. Our sensor modeling does not require ground control points and allows thus potentially for the automatic processing of large data volumes. As a proof of concept, we chose a set of glaciers with reference DEMs available to assess the quality of our measurements. We use time series of ASTER scenes from which we extracted DEMs with a ground sampling distance of 15m. Our method directly measures and accounts for the cross-track component of jitter so that the resulting DEMs are not contaminated by this process. Since the along-track component of jitter has the same direction as the stereo parallaxes, the two cannot be separated and the elevations extracted are thus contaminated by along-track jitter. Initial tests reveal no clear relation between the cross-track and along-track components so that the latter seems not to be

Mediating the Use of Global University Rankings: Perspectives from Education Facilitators in an International Context

ERIC Educational Resources Information Center

O'Connell, Catherine; Saunders, Murray

2013-01-01

This study explores responses to rankings from a group of staff working as education partnership facilitators for a professional intermediary organisation, the British Council. The study adopts an activity systems perspective from which to view the contexts in which rankings are encountered and the range of practices used to reduce tensions…

An exploration of tutors' experiences of facilitating problem-based learning. Part 2--implications for the facilitation of problem based learning.

PubMed

Haith-Cooper, Melanie

2003-01-01

This paper is the second of two parts exploring a study that was undertaken to investigate the role of the tutor in facilitating problem-based learning (PBL). The first part focussed on the methodological underpinnings of the study. This paper aims to focus on the findings of the study and their implications for the facilitation of PBL. Six essential themes emerged from the findings that described the facilitation role. The tutors believed that their facilitation role was essentially structured around the decision of when to intervene and how to intervene in the PBL process. Modelling and non-verbal communication were seen as essential strategies for the facilitator. Underpinning these decisions was the need to trust in the philosophy of PBL. However, within many of the themes, there was a divergence of opinion as to how the role should actually be undertaken. Despite this, these findings have implications for the future role of PBL facilitators in Health Professional Education.

Bilateral Alternating Auditory Stimulations Facilitate Fear Extinction and Retrieval.

PubMed

Boukezzi, Sarah; Silva, Catarina; Nazarian, Bruno; Rousseau, Pierre-François; Guedj, Eric; Valenzuela-Moguillansky, Camila; Khalfa, Stéphanie

2017-01-01

Disruption of fear conditioning, its extinction and its retrieval are at the core of posttraumatic stress disorder (PTSD). Such deficits, especially fear extinction delay, disappear after alternating bilateral stimulations (BLS) during eye movement desensitization and reprocessing (EMDR) therapy. An animal model of fear recovery, based on auditory cued fear conditioning and extinction learning, recently showed that BLS facilitate fear extinction and fear extinction retrieval. Our goal was to determine if these previous results found in animals can be reproduced in humans. Twenty-two healthy participants took part in a classical fear conditioning, extinction, and extinction recall paradigm. Behavioral responses (fear expectations) as well as psychophysiological measures (skin conductance responses, SCRs) were recorded. The results showed a significant fear expectation decrease during fear extinction with BLS. Additionally, SCR for fear extinction retrieval were significantly lower with BLS. Our results demonstrate the importance of BLS to reduce negative emotions, and provide a successful model to further explore the neural mechanisms underlying the sole BLS effect in the EMDR.

Familiarity facilitates feature-based face processing.

PubMed

Visconti di Oleggio Castello, Matteo; Wheeler, Kelsey G; Cipolli, Carlo; Gobbini, M Ida

2017-01-01

Recognition of personally familiar faces is remarkably efficient, effortless and robust. We asked if feature-based face processing facilitates detection of familiar faces by testing the effect of face inversion on a visual search task for familiar and unfamiliar faces. Because face inversion disrupts configural and holistic face processing, we hypothesized that inversion would diminish the familiarity advantage to the extent that it is mediated by such processing. Subjects detected personally familiar and stranger target faces in arrays of two, four, or six face images. Subjects showed significant facilitation of personally familiar face detection for both upright and inverted faces. The effect of familiarity on target absent trials, which involved only rejection of unfamiliar face distractors, suggests that familiarity facilitates rejection of unfamiliar distractors as well as detection of familiar targets. The preserved familiarity effect for inverted faces suggests that facilitation of face detection afforded by familiarity reflects mostly feature-based processes.

Facilitating LOS Debriefings: A Training Manual

NASA Technical Reports Server (NTRS)

McDonnell, Lori K.; Jobe, Kimberly K.; Dismukes, R. Key

1997-01-01

This manual is a practical guide to help airline instructors effectively facilitate debriefings of Line Oriented Simulations (LOS). It is based on a recently completed study of Line Oriented Flight Training (LOFT) debriefings at several U.S. airlines. This manual presents specific facilitation tools instructors can use to achieve debriefing objectives. The approach of the manual is to be flexible so it can be tailored to the individual needs of each airline. Part One clarifies the purpose and objectives of facilitation in the LOS setting. Part Two provides recommendations for clarifying roles and expectations and presents a model for organizing discussion. Part Tree suggests techniques for eliciting active crew participation and in-depth analysis and evaluation. Finally, in Part Four, these techniques are organized according to the facilitation model. Examples of how to effectively use the techniques are provided throughout, including strategies to try when the debriefing objectives are not being fully achieved.

Barriers and facilitators among health professionals in primary care to prevention of cardiometabolic diseases: A systematic review.

PubMed

Wändell, Per E; de Waard, Anne-Karien M; Holzmann, Martin J; Gornitzki, Carl; Lionis, Christos; de Wit, Niek; Søndergaard, Jens; Sønderlund, Anders L; Kral, Norbert; Seifert, Bohumil; Korevaar, Joke C; Schellevis, François G; Carlsson, Axel C

2018-01-29

The aim of this study is to identify potential facilitators and barriers for health care professionals to undertake selective prevention of cardiometabolic diseases (CMD) in primary health care. We developed a search string for Medline, Embase, Cinahl and PubMed. We also screened reference lists of relevant articles to retain barriers and facilitators for prevention of CMD. We found 19 qualitative studies, 7 quantitative studies and 2 mixed qualitative and quantitative studies. In terms of five overarching categories, the most frequently reported barriers and facilitators were as follows: Structural (barriers: time restraints, ineffective counselling and interventions, insufficient reimbursement and problems with guidelines; facilitators: feasible and effective counselling and interventions, sufficient assistance and support, adequate referral, and identification of obstacles), Organizational (barriers: general organizational problems, role of practice, insufficient IT support, communication problems within health teams and lack of support services, role of staff, lack of suitable appointment times; facilitators: structured practice, IT support, flexibility of counselling, sufficient logistic/practical support and cooperation with allied health staff/community resources, responsibility to offer and importance of prevention), Professional (barriers: insufficient counselling skills, lack of knowledge and of experience; facilitators: sufficient training, effective in motivating patients), Patient-related factors (barriers: low adherence, causes problems for patients; facilitators: strong GP-patient relationship, appreciation from patients), and Attitudinal (barriers: negative attitudes to prevention; facilitators: positive attitudes of importance of prevention). We identified several frequently reported barriers and facilitators for prevention of CMD, which may be used in designing future implementation and intervention studies. © The Author(s) 2018. Published by

Barriers and facilitators of adherence to antidepressants among outpatients with major depressive disorder: A qualitative study.

PubMed

Ho, Siew Ching; Jacob, Sabrina Anne; Tangiisuran, Balamurugan

2017-01-01

One of the major challenges in treating major depressive disorder (MDD) is patients' non-adherence to medication. This study aimed to explore the barriers and facilitators of patients' adherence to antidepressants among outpatients with MDD. Semi-structured and individual in-depth interviews were conducted among patients with MDD who were taking antidepressants, in the psychiatric clinic of a government-run hospital in Malaysia. Participants were purposively sampled from different genders and ethnicities. Interviews were conducted using a validated topic guide, and responses were audio-recorded, transcribed verbatim, checked, and analyzed using the grounded theory approach. A total of 30 patients were interviewed. Forty different themes and sub-themes were identified which were conceptually divided into two distinct categories related to barriers and facilitators to adherence. The barriers were: patient-specific, medication-specific, healthcare provision and system, social-cultural, and logistics. The facilitators were: having insight, perceived health benefits, regular activities, patient-provider relationship, reminders, and social support networks. Patient-specific barriers and medication side effects were the major challenges for adhering to treatment. Perceived health benefits and having insight on the need for treatment were the most frequently cited facilitators. Targeted interventions should be developed to address the key barriers, and promote measures to facilitate adherence in this group of patients.

Facilitating Scholarly Writing in Academic Medicine

PubMed Central

Pololi, Linda; Knight, Sharon; Dunn, Kathleen

2004-01-01

Scholarly writing is a critical skill for faculty in academic medicine; however, few faculty receive instruction in the process. We describe the experience of 18 assistant professors who participated in a writing and faculty development program which consisted of 7 monthly 75-minute sessions embedded in a Collaborative Mentoring Program (CMP). Participants identified barriers to writing, developed personal writing strategies, had time to write, and completed monthly writing contracts. Participants provided written responses to open-ended questions about the learning experience, and at the end of the program, participants identified manuscripts submitted for publication, and completed an audiotaped interview. Analysis of qualitative data using data reduction, data display, and conclusion drawing/verification showed that this writing program facilitated the knowledge, skills, and support needed to foster writing productivity. All participants completed at least 1 scholarly manuscript by the end of the CMP. The impact on participants’ future academic productivity requires long-term follow-up. PMID:14748862

Induction of a Cellular DNA Damage Response by Porcine Circovirus Type 2 Facilitates Viral Replication and Mediates Apoptotic Responses

PubMed Central

Wei, Li; Zhu, Shanshan; Wang, Jing; Quan, Rong; Yan, Xu; Li, Zixue; Hou, Lei; Wang, Naidong; Yang, Yi; Jiang, Haijun; Liu, Jue

2016-01-01

Cellular DNA damage response (DDR) triggered by infection of DNA viruses mediate cell cycle checkpoint activation, DNA repair, or apoptosis induction. In the present study, infection of porcine circovirus type 2 (PCV2), which serves as a major etiological agent of PCV2-associated diseases (PCVAD), was found to elicit a DNA damage response (DDR) as observed by the phosphorylation of H2AX and RPA32 following infection. The response requires active viral replication, and all the ATM (ataxia telangiectasia-mutated kinase), ATR (ATM- and Rad3-related kinase), and DNA-PK (DNA-dependent protein kinase) are the transducers of the DDR signaling events in the PCV2-infected cells as demonstrated by the phosphorylation of ATM, ATR, and DNA-PK signalings as well as reductions in their activations after treatment with specific kinase inhibitors. Inhibitions of ATM, ATR, and DNA-PK activations block viral replication and prevent apoptotic responses as observed by decreases in cleaved poly-ADP ribose polymerase (PARP) and caspase-3 as well as fragmented DNA following PCV2 infection. These results reveal that PCV2 is able to exploit the cellular DNA damage response machinery for its own efficient replication and for apoptosis induction, further extending our understanding for the molecular mechanism of PCV2 infection. PMID:27982097

National Offshore Wind Strategy: Facilitating the Development of the Offshore Wind Industry in the United States

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patrick Gilman; Maurer, Ben; Feinberg, Luke

2016-09-01

The U.S. Department of Energy, through its Wind Energy Technologies Office, and U.S. Department of the Interior, through its Bureau of Ocean Energy Management, have jointly produced this updated national strategy to facilitate the responsible development of offshore wind energy in the United States.

Noninvasive assessment of the facilitation of the nociceptive withdrawal reflex by repeated electrical stimulations in conscious dogs.

PubMed

Bergadano, Alessandra; Andersen, Ole K; Arendt-Nielsen, Lars; Spadavecchia, Claudia

2007-08-01

To investigate the facilitation of the nociceptive withdrawal reflex (NWR) by repeated electrical stimuli and the associated behavioral response scores in conscious, nonmedicated dogs as a measure of temporal summation and analyze the influence of stimulus intensity and frequency on temporal summation responses. 8 adult Beagles. Surface electromyographic responses evoked by transcutaneous constant-current electrical stimulation of ulnaris and digital plantar nerves were recorded from the deltoideus, cleidobrachialis, biceps femoris, and cranial tibial muscles. A repeated stimulus was given at 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, and 1.1 x I(t) (the individual NWR threshold intensity) at 2, 5, and 20 Hz. Threshold intensity and relative amplitude and latency of the reflex were analyzed for each stimulus configuration. Behavioral reactions were subjectively scored. Repeated sub-I(t) stimuli summated and facilitated the NWR. To elicit temporal summation, significantly lower intensities were needed for the hind limb, compared with the forelimb. Stimulus frequency did not influence temporal summation, whereas increasing intensity resulted in significantly stronger electromyographic responses and nociception (determined via behavioral response scoring) among the dogs. In dogs, it is possible to elicit nociceptive temporal summation that correlates with behavioral reactions. These data suggest that this experimental technique can be used to evaluate nociceptive system excitability and efficacy of analgesics in canids.

Toward Facilitative Mentoring and Catalytic Interventions

ERIC Educational Resources Information Center

Smith, Melissa K.; Lewis, Marilyn

2015-01-01

In TESOL teacher mentoring, giving advice can be conceptualized as a continuum, ranging from directive to facilitative feedback. The goal, over time, is to lead toward the facilitative end of the continuum and specifically to catalytic interventions that encourage self-reflection and autonomous learning. This study begins by examining research on…

Jitter compensation circuit

DOEpatents

Sullivan, James S.; Ball, Don G.

1997-01-01

The instantaneous V.sub.co signal on a charging capacitor is sampled and the charge voltage on capacitor C.sub.o is captured just prior to its discharge into the first stage of magnetic modulator. The captured signal is applied to an averaging circuit with a long time constant and to the positive input terminal of a differential amplifier. The averaged V.sub. co signal is split between a gain stage (G=0.975) and a feedback stage that determines the slope of the voltage ramp applied to the high speed comparator. The 97.5% portion of the averaged V.sub.co signal is applied to the negative input of a differential amplifier gain stage (G=10). The differential amplifier produces an error signal by subtracting 97.5% of the averaged V.sub.co signal from the instantaneous value of sampled V.sub.co signal and multiplying the difference by ten. The resulting error signal is applied to the positive input of a high speed comparator. The error signal is then compared to a voltage ramp that is proportional to the averaged V.sub.co values squared divided by the total volt-second product of the magnetic compression circuit.

Jitter compensation circuit

DOEpatents

Sullivan, J.S.; Ball, D.G.

1997-09-09

The instantaneous V{sub co} signal on a charging capacitor is sampled and the charge voltage on capacitor C{sub o} is captured just prior to its discharge into the first stage of magnetic modulator. The captured signal is applied to an averaging circuit with a long time constant and to the positive input terminal of a differential amplifier. The averaged V{sub co} signal is split between a gain stage (G = 0.975) and a feedback stage that determines the slope of the voltage ramp applied to the high speed comparator. The 97.5% portion of the averaged V{sub co} signal is applied to the negative input of a differential amplifier gain stage (G = 10). The differential amplifier produces an error signal by subtracting 97.5% of the averaged V{sub co} signal from the instantaneous value of sampled V{sub co} signal and multiplying the difference by ten. The resulting error signal is applied to the positive input of a high speed comparator. The error signal is then compared to a voltage ramp that is proportional to the averaged V{sub co} values squared divided by the total volt-second product of the magnetic compression circuit. 11 figs.

Facilitators for practice change in Spanish community pharmacy.

PubMed

Gastelurrutia, Miguel A; Benrimoj, S I Charlie; Castrillon, Carla C; de Amezua, María J Casado; Fernandez-Llimos, Fernando; Faus, Maria J

2009-02-01

To identify and prioritise facilitators for practice change in Spanish community pharmacy. Spanish community pharmacies. Qualitative study. Thirty-three semi-structured interviews were conducted with community pharmacists (n = 15) and pharmacy strategists (n = 18), and the results were examined using the content analysis method. In addition, two nominal groups (seven community pharmacists and seven strategists) were formed to identify and prioritise facilitators. Results of both techniques were then triangulated. Facilitators for practice change. Twelve facilitators were identified and grouped into four domains (D1: Pharmacist; D2: Pharmacy as an organisation; D3: Pharmaceutical profession; D4: Miscellaneous). Facilitators identified in D1 include: the need for more clinical education at both pre- and post-graduate levels; the need for clearer and unequivocal messages from professional leaders about the future of the professional practice; and the need for a change in pharmacists' attitudes. Facilitators in D2 are: the need to change the reimbursement system to accommodate cognitive service delivery as well as dispensing; and the need to change the front office of pharmacies. Facilitators identified in D3 are: the need for the Spanish National Professional Association to take a leadership role in the implementation of cognitive services; the need to reduce administrative workload; and the need for universities to reduce the gap between education and research. Other facilitators identified in this study include: the need to increase patients' demand for cognitive services at pharmacies; the need to improve pharmacist-physician relationships; the need for support from health care authorities; and the need for improved marketing of cognitive services and their benefits to society, including physicians and health care authorities. Twelve facilitators were identified. Strategists considered clinical education and pharmacists' attitude as the most important, and

With a little help from my goals: integrating intergoal facilitation with the theory of planned behaviour to predict physical activity.

PubMed

Presseau, Justin; Sniehotta, Falko F; Francis, Jill J; Gebhardt, Winifred A

2010-11-01

Integration of a multiple goal theory approach into the theory of planned behaviour (TPB) to investigate how the perceived facilitating and conflicting relationships in multiple goal pursuit predict performance of a health-related behaviour. Prospective design with 8-week follow-up. At baseline, perceived intergoal facilitation and intergoal conflict were measured using personal projects analysis supplemented with standard TPB measures for physical activity (PA). Self-reported PA was measured at follow-up 8 weeks later. N=137 participants completed measures at both time points (55.4% response rate at follow-up). Hierarchical regression showed that perceived intergoal facilitation, but not intergoal conflict, directly predicted PA beyond intention and perceived behavioural control (PBC), accounting for more than 4% of additional variance in PA. Intergoal facilitation had an indirect effect on intention through attitude and PBC, and intention partially mediated the effect of intergoal facilitation on behaviour. The perceived facilitating effect of pursuing other personal goals predicts the performance of a health-related behaviour over and above single behaviour-focused social cognitions.

Noradrenergic facilitation of shock-probe defensive burying in lateral septum of rats, and modulation by chronic treatment with desipramine.

PubMed

Bondi, Corina O; Barrera, Gabriel; Lapiz, M Danet S; Bedard, Tania; Mahan, Amy; Morilak, David A

2007-03-30

We have previously shown that acute stress-induced release of norepinephrine (NE) facilitates anxiety-like behavioral responses to stress, such as reduction in open-arm exploration on the elevated-plus maze and in social behavior on the social interaction test. Since these responses represent inhibition of ongoing behavior, it is important to also address whether NE facilitates a response that represents an activation of behavior. Correspondingly, it is unknown how a chronic elevation in tonic steady-state noradrenergic (NA) neurotransmission induced by NE reuptake blockade might alter this acute modulatory function, a regulatory process that may be pertinent to the anxiolytic effects of NE reuptake blockers such as desipramine (DMI). Therefore, in this study, we investigated noradrenergic modulation of the shock-probe defensive burying response in the lateral septum (LS). In experiment 1, shock-probe exposure induced an acute 3-fold increase in NE levels measured in LS of male Sprague-Dawley rats by microdialysis. Shock-probe exposure also induced a modest rise in plasma ACTH, taken as an indicator of perceived stress, that returned to baseline more rapidly in rats that were allowed to bury the probe compared to rats prevented from burying by providing them with minimal bedding, indicating that the active defensive burying behavior is an effective coping strategy that reduces the impact of acute shock probe-induced stress. In experiment 2, blockade of either alpha(1)- or beta-adrenergic receptors in LS by local antagonist microinjection immediately before testing reduced defensive burying and increased immobility. In the next experiment, chronic DMI treatment increased basal extracellular NE levels in LS, and attenuated the acute shock probe-induced increase in NE release in LS relative to baseline. Chronic DMI treatment decreased shock-probe defensive burying behavior in a time-dependent manner, apparent only after 2 weeks or more of drug treatment. Moreover

Producing Gestures Facilitates Route Learning

PubMed Central

So, Wing Chee; Ching, Terence Han-Wei; Lim, Phoebe Elizabeth; Cheng, Xiaoqin; Ip, Kit Yee

2014-01-01

The present study investigates whether producing gestures would facilitate route learning in a navigation task and whether its facilitation effect is comparable to that of hand movements that leave physical visible traces. In two experiments, we focused on gestures produced without accompanying speech, i.e., co-thought gestures (e.g., an index finger traces the spatial sequence of a route in the air). Adult participants were asked to study routes shown in four diagrams, one at a time. Participants reproduced the routes (verbally in Experiment 1 and non-verbally in Experiment 2) without rehearsal or after rehearsal by mentally simulating the route, by drawing it, or by gesturing (either in the air or on paper). Participants who moved their hands (either in the form of gestures or drawing) recalled better than those who mentally simulated the routes and those who did not rehearse, suggesting that hand movements produced during rehearsal facilitate route learning. Interestingly, participants who gestured the routes in the air or on paper recalled better than those who drew them on paper in both experiments, suggesting that the facilitation effect of co-thought gesture holds for both verbal and nonverbal recall modalities. It is possibly because, co-thought gesture, as a kind of representational action, consolidates spatial sequence better than drawing and thus exerting more powerful influence on spatial representation. PMID:25426624

Interorganisational Integration: Healthcare Professionals’ Perspectives on Barriers and Facilitators within the Danish Healthcare System

PubMed Central

Godtfredsen, Nina Skavlan; Frølich, Anne

2016-01-01

Introduction: Despite many initiatives to improve coordination of patient pathways and intersectoral cooperation, Danish health care is still fragmented, lacking intra- and interorganisational integration. This study explores barriers to and facilitators of interorganisational integration as perceived by healthcare professionals caring for patients with chronic obstructive pulmonary disease within the Danish healthcare system. Methods: Seven focus groups were conducted in January through July 2014 with 21 informants from general practice, local healthcare centres and a pulmonary department at a university hospital in the Capital Region of Denmark. Results and discussion: Our results can be grouped into five influencing areas for interorganisational integration: communication/information transfer, committed leadership, patient engagement, the role and competencies of the general practitioner and organisational culture. Proposed solutions to barriers in each area hold the potential to improve care integration as experienced by individuals responsible for supporting and facilitating it. Barriers and facilitators to integrating care relate to clinical, professional, functional and normative integration. Especially, clinical, functional and normative integration seems fundamental to developing integrated care in practice from the perspective of healthcare professionals. PMID:27616948

Understanding American-Indian children’s perceived barriers and facilitators to following the Dietary Guidelines for Americans (DGA)

USDA-ARS?s Scientific Manuscript database

Ninety-two American Indian 5th graders from a rural, northern plains reservation community completed Nominal Group Technique (NGT) sessions designed to understand both barriers and facilitators to following DGA. Individually and in small groups, children generated lists of responses to specific que...

Facilitating classroom based interprofessional learning: a grounded theory study of university educators' perceptions of their role adequacy as facilitators.

PubMed

Derbyshire, Julie A; Machin, Alison I; Crozier, Suzanne

2015-01-01

The provision of inter professional learning (IPL) within undergraduate programmes is now well established within many Higher Education Institutions (HEIs). IPL aims to better equip nurses and other health professionals with effective collaborative working skills and knowledge to improve the quality of patient care. Although there is still ambiguity in relation to the optimum timing and method for delivering IPL, effective facilitation is seen as essential. This paper reports on a grounded theory study of university educators' perceptions of the knowledge and skills needed for their role adequacy as IPL facilitators. Data was collected using semi structured interviews with nine participants who were theoretically sampled from a range of professional backgrounds, with varied experiences of education and involvement in facilitating IPL. Constant comparative analysis was used to generate four data categories: creating and sustaining an IPL group culture through transformational IPL leadership (core category), readiness for IPL facilitation, drawing on past interprofessional learning and working experiences and role modelling an interprofessional approach. The grounded theory generated from this study, although propositional, suggests that role adequacy for IPL facilitation is dependent on facilitator engagement in a process of 'transformational interprofessional learning leadership' to create and sustain a group culture. Copyright © 2014 Elsevier Ltd. All rights reserved.

Particle acceleration, magnetic field generation, and emission in relativistic pair jets

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Ramirez-Ruiz, E.; Hardee, P.; Hededal, C.; Kouveliotou, C.; Fishman, G. J.; Mizuno, Y.

2005-01-01

Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Recent simulations show that the Weibel instability created by relativistic pair jets is responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet propagating through an ambient plasma with and without initial magnetic fields. The growth rates of the Weibel instability depends on the distribution of pair jets. The Weibel instability created in the collisionless shock accelerates particles perpendicular and parallel to the jet propagation direction. This instability is also responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron s transverse deflection behind the jet head. The jitter radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

Facilitating Cognitive Development.

ERIC Educational Resources Information Center

Schwebel, Milton

1985-01-01

Human cognition research is shifting away from the importance of IQ and is emphasizing the stimulation and acceleration of a child's mental development. The emerging field of instructional psychology is trying to facilitate cognitive development. Current experimental programs--a university-school project in Belgium and a family project in…

Physically facilitating drug-delivery systems

PubMed Central

Rodriguez-Devora, Jorge I; Ambure, Sunny; Shi, Zhi-Dong; Yuan, Yuyu; Sun, Wei; Xu, Tao

2012-01-01

Facilitated/modulated drug-delivery systems have emerged as a possible solution for delivery of drugs of interest to pre-allocated sites at predetermined doses for predefined periods of time. Over the past decade, the use of different physical methods and mechanisms to mediate drug release and delivery has grown significantly. This emerging area of research has important implications for development of new therapeutic drugs for efficient treatments. This review aims to introduce and describe different modalities of physically facilitating drug-delivery systems that are currently in use for cancer and other diseases therapy. In particular, delivery methods based on ultrasound, electrical, magnetic and photo modulations are highlighted. Current uses and areas of improvement for these different physically facilitating drug-delivery systems are discussed. Furthermore, the main advantages and drawbacks of these technologies reviewed are compared. The review ends with a speculative viewpoint of how research is expected to evolve in the upcoming years. PMID:22485192

3-D RPIC Simulations of Relativistic Jets: Particle Acceleration, Magnetic Field Generation, and Emission

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Mizuno, Y.; Hardee, P.; Hededal, C. B.; Fishman, G. J.

2006-01-01

Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets into ambient plasmas show that acceleration occurs in relativistic shocks. The Weibel instability created in shocks is responsible for particle acceleration, and generation and amplification of highly inhomogeneous, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection in relativistic jets. The "jitter" radiation from deflected electrons has different properties than the synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understand the complex time evolution and spectral structure in relativistic jets and gamma-ray bursts. We will present recent PIC simulations which show particle acceleration and magnetic field generation. We will also calculate associated self-consistent emission from relativistic shocks.

Facilitating the Design of a Campus Leadership Team

ERIC Educational Resources Information Center

Meyers, Renee A.; Johnson, John R.

2008-01-01

This essay describes how we facilitated the design of a campus leadership team. What is particularly interesting about this consultative project is that both authors participated--one as facilitator and the other as participant. The facilitation included a needs assessment prior to the event, the use of structured controversy techniques,…

Leptin: a potential anxiolytic by facilitation of fear extinction.

PubMed

Wang, Wei; Liu, Song-Lin; Li, Kuan; Chen, Yu; Jiang, Bo; Li, Yan-Kun; Xiao, Jun-Li; Yang, Si; Chen, Tao; Chen, Jian-Guo; Li, Jia-Geng; Wang, Fang

2015-05-01

Anxiety disorders are characterized by a deficient extinction of fear memory. Evidence is growing that leptin influences numerous neuronal functions. The aims of this study were to investigate the effects and the mechanism of leptin on fear extinction. Leptin (1 mg/kg, i.p) was applied to evaluate the anxiolytic effect in rat behavioral tests. Field potentials recording were used to investigate the changes in synaptic transmission in the thalamic-lateral amygadala (LA) pathway of rat. We found that leptin produced strong anxiolytic effects under basal condition and after acute stress. Systemic administration and intra-LA infusions of leptin facilitated extinction of conditioned fear responses. The antagonist of NMDA receptor, MK-801, blocked the effect of leptin on fear extinction completely. Furthermore, these effects of leptin on fear extinction were accompanied by a reversal of conditioning-induced synaptic potentiation in the LA. Leptin facilitated NMDA receptor-mediated synaptic transmission, and reversed amygdala long-term potentiation (LTP) in a dose-dependent manner in vitro, and this LTP depotentiation effect was mediated by NMDA receptor and MAPK signaling pathway. These results identify a key role of leptin in dampening fear conditioning-induced synaptic potentiation in the LA through NMDA receptor and indicate a new strategy for treating anxiety disorders. © 2015 John Wiley & Sons Ltd.

Facilitating Distance Education.

ERIC Educational Resources Information Center

Rossman, Mark H., Ed.; Rossman, Maxine E., Ed.

1995-01-01

This collection of articles on distance learning reflects the perspectives and concerns of the learner and the facilitator of learning in distance education setting. Eight chapters are included: (1) "The Evolution and Advantages of Distance Education" (John E. Cantelon) traces the history of distance education and demonstrates how it transcends…

50 CFR 600.752 - Use of conveners and facilitators.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Use of conveners and facilitators. 600.752..., by consensus. The facilitator may be the same person as the convener used under paragraph (a) of this... facilitator, the FNP shall select, by consensus, a person to serve as facilitator. A person designated to...

Microswitch and Keyboard-Emulator Technology to Facilitate the Writing Performance of Persons with Extensive Motor Disabilities

ERIC Educational Resources Information Center

Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; Green, Vanessa; Oliva, Doretta; Lang, Russell

2011-01-01

This study assessed the effectiveness of microswitches for simple responses (i.e., partial hand closure, vocalization, and hand stroking) and a keyboard emulator to facilitate the writing performance of three participants with extensive motor disabilities. The study was carried out according to an ABAB design. During the A phases, the participants…

What Happened to the World? Helping Children Cope in Turbulent Times. Facilitator's Guide [and Student's Guide].

ERIC Educational Resources Information Center

Greenman, Jim

In response to the September 11th, 2001 terrorists attacks, "Comfort for Kids" was formed as a collaborative effort to provide support and resources to children and families directly affected. This facilitator's guide and student's guide represent one part of the three-pronged approach of the "Comfort for Kids" program. The…

Development of an interprofessional lean facilitator assessment scale.

PubMed

Bravo-Sanchez, Cindy; Dorazio, Vincent; Denmark, Robert; Heuer, Albert J; Parrott, J Scott

2018-05-01

High reliability is important for optimising quality and safety in healthcare organisations. Reliability efforts include interprofessional collaborative practice (IPCP) and Lean quality/process improvement strategies, which require skilful facilitation. Currently, no validated Lean facilitator assessment tool for interprofessional collaboration exists. This article describes the development and pilot evaluation of such a tool; the Interprofessional Lean Facilitator Assessment Scale (ILFAS), which measures both technical and 'soft' skills, which have not been measured in other instruments. The ILFAS was developed using methodologies and principles from Lean/Shingo, IPCP, metacognition research and Bloom's Taxonomy of Learning Domains. A panel of experts confirmed the initial face validity of the instrument. Researchers independently assessed five facilitators, during six Lean sessions. Analysis included quantitative evaluation of rater agreement. Overall inter-rater agreement of the assessment of facilitator performance was high (92%), and discrepancies in the agreement statistics were analysed. Face and content validity were further established, and usability was evaluated, through primary stakeholder post-pilot feedback, uncovering minor concerns, leading to tool revision. The ILFAS appears comprehensive in the assessment of facilitator knowledge, skills, abilities, and may be useful in the discrimination between facilitators of different skill levels. Further study is needed to explore instrument performance and validity.

Investigating the complementary value of discrete choice experiments for the evaluation of barriers and facilitators in implementation research: a questionnaire survey

PubMed Central

van Helvoort-Postulart, Debby; van der Weijden, Trudy; Dellaert, Benedict GC; de Kok, Mascha; von Meyenfeldt, Maarten F; Dirksen, Carmen D

2009-01-01

Background The potential barriers and facilitators to change should guide the choice of implementation strategy. Implementation researchers believe that existing methods for the evaluation of potential barriers and facilitators are not satisfactory. Discrete choice experiments (DCE) are relatively new in the health care sector to investigate preferences, and may be of value in the field of implementation research. The objective of our study was to investigate the complementary value of DCE for the evaluation of barriers and facilitators in implementation research. Methods Clinical subject was the implementation of the guideline for breast cancer surgery in day care. We identified 17 potential barriers and facilitators to the implementation of this guideline. We used a traditional questionnaire that was made up of statements about the potential barriers and facilitators. Respondents answered 17 statements on a five-point scale ranging from one (fully disagree) to five (fully agree). The potential barriers and facilitators were included in the DCE as decision attributes. Data were gathered among anaesthesiologists, surgical oncologists, and breast care nurses by means of a paper-and-pencil questionnaire. Results The overall response was 10%. The most striking finding was that the responses to the traditional questionnaire hardly differentiated between barriers. Forty-seven percent of the respondents thought that DCE is an inappropriate method. These respondents considered DCE too difficult and too time-consuming. Unlike the traditional questionnaire, the results of a DCE provide implementation researchers and clinicians with a relative attribute importance ranking that can be used to prioritize potential barriers and facilitators to change, and hence to better fine-tune the implementation strategies to the specific problems and challenges of a particular implementation process. Conclusion The results of our DCE and traditional questionnaire would probably lead to

Interference and facilitation in overt speech production investigated with event-related potentials.

PubMed

Hirschfeld, Gerrit; Jansma, Bernadette; Bölte, Jens; Zwitserlood, Pienie

2008-08-06

We report an event-related potential study investigating the neural basis of interference and facilitation in the picture-word interference paradigm with immediate overt naming. We used the high temporal resolution of the electrophysiological response to dissociate general and specific interference processes, by comparing unrelated word distractors to nonlinguistic (a row of Xs), surface feature denoting, and category member distractors. Our results first indicate that the increased naming latencies for linguistic relative to nonlinguistic distractors are because of general conflict-monitoring processes, associated with early event-related potential effects (120-220 ms) and increased activity in the anterior cingulate cortex. Next, distractors specifying a surface feature of the picture seem to facilitate its identification within the same time window, which involves widespread networks. Finally, nonlinguistic and surface feature distractors also reduced the N400 amplitude, relative to unrelated word distractors. Taken together our results support the view that several distinct processes give rise to the reaction time results often observed in picture naming.

Barriers and facilitators of adherence to antidepressants among outpatients with major depressive disorder: A qualitative study

PubMed Central

Jacob, Sabrina Anne; Tangiisuran, Balamurugan

2017-01-01

Background One of the major challenges in treating major depressive disorder (MDD) is patients’ non-adherence to medication. This study aimed to explore the barriers and facilitators of patients’ adherence to antidepressants among outpatients with MDD. Methods Semi-structured and individual in-depth interviews were conducted among patients with MDD who were taking antidepressants, in the psychiatric clinic of a government-run hospital in Malaysia. Participants were purposively sampled from different genders and ethnicities. Interviews were conducted using a validated topic guide, and responses were audio-recorded, transcribed verbatim, checked, and analyzed using the grounded theory approach. Results A total of 30 patients were interviewed. Forty different themes and sub-themes were identified which were conceptually divided into two distinct categories related to barriers and facilitators to adherence. The barriers were: patient-specific, medication-specific, healthcare provision and system, social-cultural, and logistics. The facilitators were: having insight, perceived health benefits, regular activities, patient-provider relationship, reminders, and social support networks. Conclusions Patient-specific barriers and medication side effects were the major challenges for adhering to treatment. Perceived health benefits and having insight on the need for treatment were the most frequently cited facilitators. Targeted interventions should be developed to address the key barriers, and promote measures to facilitate adherence in this group of patients. PMID:28614368

Intracortical inhibition and facilitation with unilateral dominant, unilateral nondominant and bilateral movement tasks in left- and right-handed adults.

PubMed

McCombe Waller, Sandy; Forrester, Larry; Villagra, Federico; Whitall, Jill

2008-06-15

To investigate intracortical inhibition and facilitation in response to unilateral dominant, nondominant and bilateral biceps activation and short-term upper extremity training in right- and left-handed adults. Paired-pulse transcranial magnetic stimulation was used to measure intracortical excitability in motor dominant and nondominant cortices of 26 nondisabled adults. Neural facilitation and inhibition were measured in each hemisphere during unilateral dominant, nondominant and bilateral arm activation and after training in each condition. No differences were seen between right- and left-handed subjects. Intracortical facilitation and decreased inhibition were seen in each hemisphere with unilateral activation/training of contralateral muscles and bilateral muscle activation/training. Persistent intracortical inhibition was seen in each hemisphere with ipsilateral muscle activation/training. Inhibition was greater in the nondominant hemisphere during dominant hemisphere activation (dominant arm contraction). Strongly dominant individuals show no difference in intracortical responses given handedness. Intracortical activity with unilateral and bilateral arm activation and short-term training differs based on hemispheric dominance, with the motor dominant hemisphere exerting a larger inhibitory influence over the nondominant hemisphere. Bilateral activation and training have a disinhibitory effect in both dominant and nondominant hemispheres.

Spike Timing and Reliability in Cortical Pyramidal Neurons: Effects of EPSC Kinetics, Input Synchronization and Background Noise on Spike Timing

PubMed Central

Rodriguez-Molina, Victor M.; Aertsen, Ad; Heck, Detlef H.

2007-01-01

In vivo studies have shown that neurons in the neocortex can generate action potentials at high temporal precision. The mechanisms controlling timing and reliability of action potential generation in neocortical neurons, however, are still poorly understood. Here we investigated the temporal precision and reliability of spike firing in cortical layer V pyramidal cells at near-threshold membrane potentials. Timing and reliability of spike responses were a function of EPSC kinetics, temporal jitter of population excitatory inputs, and of background synaptic noise. We used somatic current injection to mimic population synaptic input events and measured spike probability and spike time precision (STP), the latter defined as the time window (Δt) holding 80% of response spikes. EPSC rise and decay times were varied over the known physiological spectrum. At spike threshold level, EPSC decay time had a stronger influence on STP than rise time. Generally, STP was highest (≤2.45 ms) in response to synchronous compounds of EPSCs with fast rise and decay kinetics. Compounds with slow EPSC kinetics (decay time constants>6 ms) triggered spikes at lower temporal precision (≥6.58 ms). We found an overall linear relationship between STP and spike delay. The difference in STP between fast and slow compound EPSCs could be reduced by incrementing the amplitude of slow compound EPSCs. The introduction of a temporal jitter to compound EPSCs had a comparatively small effect on STP, with a tenfold increase in jitter resulting in only a five fold decrease in STP. In the presence of simulated synaptic background activity, precisely timed spikes could still be induced by fast EPSCs, but not by slow EPSCs. PMID:17389910

Barriers and Facilitators of HIV Care Engagement: Results of a Qualitative Study in St. Petersburg, Russia

PubMed Central

Kuznetsova, Anna V.; Meylakhs, Anastasia Y.; Amirkhanian, Yuri A.; Kelly, Jeffrey A.; Yakovlev, Alexey A.; Musatov, Vladimir B.; Amirkhanian, Anastasia G.

2016-01-01

Russia has a large HIV epidemic, but medical care engagement is low. Eighty HIV-positive persons in St. Petersburg completed in-depth interviews to identify barriers and facilitators of medical HIV care engagement. The most commonly-reported barriers involved difficulties accessing care providers, dissatisfaction with the quality of services, and negative attitudes of provider staff. Other barriers included not having illness symptoms, life stresses, low value placed on health, internalized stigma and wanting to hide one’s HIV status, fears of learning about one’s true health status, and substance abuse. Care facilitators were feeling responsible for one’s health and one’s family, care-related support from other HIV-positive persons, and the onset of health decline and fear of death. Substance use remission facilitated care engagement, as did good communication from providers and trust in one’s doctor. Interventions are needed in Russia to address HIV care infrastructural barriers and integrate HIV, substance abuse, care, and psychosocial services. PMID:26767534

Barriers and Facilitators of HIV Care Engagement: Results of a Qualitative Study in St. Petersburg, Russia.

PubMed

Kuznetsova, Anna V; Meylakhs, Anastasia Y; Amirkhanian, Yuri A; Kelly, Jeffrey A; Yakovlev, Alexey A; Musatov, Vladimir B; Amirkhanian, Anastasia G

2016-10-01

Russia has a large HIV epidemic, but medical care engagement is low. Eighty HIV-positive persons in St. Petersburg completed in-depth interviews to identify barriers and facilitators of medical HIV care engagement. The most commonly-reported barriers involved difficulties accessing care providers, dissatisfaction with the quality of services, and negative attitudes of provider staff. Other barriers included not having illness symptoms, life stresses, low value placed on health, internalized stigma and wanting to hide one's HIV status, fears of learning about one's true health status, and substance abuse. Care facilitators were feeling responsible for one's health and one's family, care-related support from other HIV-positive persons, and the onset of health decline and fear of death. Substance use remission facilitated care engagement, as did good communication from providers and trust in one's doctor. Interventions are needed in Russia to address HIV care infrastructural barriers and integrate HIV, substance abuse, care, and psychosocial services.

Visual Stimulation Facilitates Penile Responses to Vibration in Men with and without Erectile Disorder.

ERIC Educational Resources Information Center

Janssen, Erick; And Others

1994-01-01

Compared reflexogenic and psychogenic penile responses in men with and without erectile disorder. Hypothesized that men with psychogenic dysfunction respond minimally to vibrotactile stimulation. As predicted, responses were different in the vibration condition. Interpretations are provided in terms of attention and appraisal. (BF)

Barriers and Facilitators of HPV Vaccination in the VFC Program.

PubMed

Fleming, Wayne S; Sznajder, Kristin K; Nepps, Margaret; Boktor, Sameh W

2018-06-01

This study determined facilitators and barriers to human papillomavirus (HPV) vaccination perceived by providers of healthcare in the federally funded Pennsylvania Vaccines for Children (PA VFC) program. The cross-sectional study gathered descriptive data through a survey research design. Providers of healthcare were recruited through an email containing a link to an 18-question online survey. The survey was divided into four main sections which assessed the perceived facilitators and barriers to HPV vaccination of PA VFC program-eligibles. Survey respondents represented 65 of 66 Pennsylvania counties covered by the PA VFC Program. The study recruited 772 PA VFC participating healthcare facilities for a response rate of 52%. Ninety eight percent of the responding facilities reported that they offered the HPV vaccine. The most common barriers to vaccine administration were the parental belief that HPV vaccination is associated with sexual activity and parent/patient refusal of the HPV vaccination which together accounted for (44%) of responses. The majority of respondents (75.6%) indicated counseling parents and adolescents on the benefits of HPV vaccination was a very important factor in HPV vaccination uptake. Healthcare provider facility based training (32%) and web-based training for healthcare providers (22%) were the most recommended avenues for HPV training. The most common barrier to HPV vaccination was identified as the parental misconception that HPV vaccination is associated with sexual activity. Providers believed that the best way to increase HPV vaccination is through counseling parents and adolescents on the benefits of HPV vaccination and to correct misconceptions and change attitudes. Providers are desirous of receiving HPV web-based or workplace training.

Facilitating post traumatic growth

PubMed Central

Turner, de Sales; Cox, Helen

2004-01-01

Background Whilst negative responses to traumatic injury have been well documented in the literature, there is a small but growing body of work that identifies posttraumatic growth as a salient feature of this experience. We contribute to this discourse by reporting on the experiences of 13 individuals who were traumatically injured, had undergone extensive rehabilitation and were discharged from formal care. All participants were injured through involvement in a motor vehicle accident, with the exception of one, who was injured through falling off the roof of a house. Methods In this qualitative study, we used an audio-taped in-depth interview with each participant as the means of data collection. Interviews were transcribed verbatim and analysed thematically to determine the participants' unique perspectives on the experience of recovery from traumatic injury. In reporting the findings, all participants' were given a pseudonym to assure their anonymity. Results Most participants indicated that their involvement in a traumatic occurrence was a springboard for growth that enabled them to develop new perspectives on life and living. Conclusion There are a number of contributions that health providers may make to the recovery of individuals who have been traumatically injured to assist them to develop new views of vulnerability and strength, make changes in relationships, and facilitate philosophical, physical and spiritual growth. PMID:15248894

Bilateral Alternating Auditory Stimulations Facilitate Fear Extinction and Retrieval

PubMed Central

Boukezzi, Sarah; Silva, Catarina; Nazarian, Bruno; Rousseau, Pierre-François; Guedj, Eric; Valenzuela-Moguillansky, Camila; Khalfa, Stéphanie

2017-01-01

Disruption of fear conditioning, its extinction and its retrieval are at the core of posttraumatic stress disorder (PTSD). Such deficits, especially fear extinction delay, disappear after alternating bilateral stimulations (BLS) during eye movement desensitization and reprocessing (EMDR) therapy. An animal model of fear recovery, based on auditory cued fear conditioning and extinction learning, recently showed that BLS facilitate fear extinction and fear extinction retrieval. Our goal was to determine if these previous results found in animals can be reproduced in humans. Twenty-two healthy participants took part in a classical fear conditioning, extinction, and extinction recall paradigm. Behavioral responses (fear expectations) as well as psychophysiological measures (skin conductance responses, SCRs) were recorded. The results showed a significant fear expectation decrease during fear extinction with BLS. Additionally, SCR for fear extinction retrieval were significantly lower with BLS. Our results demonstrate the importance of BLS to reduce negative emotions, and provide a successful model to further explore the neural mechanisms underlying the sole BLS effect in the EMDR. PMID:28659851

Emotionally positive stimuli facilitate lexical decisions-an ERP study.

PubMed

Kissler, Johanna; Koessler, Susanne

2011-03-01

The influence of briefly presented positive and negative emotional pictures on lexical decisions on positive, negative and neutral words or pseudowords was investigated. Behavioural reactions were the fastest following all positive stimuli and most accurate for positive words. Stimulus-locked ERPs revealed enhanced early posterior and late parietal attention effects following positive pictures. A small neural affective priming effect was reflected by P3 modulation, indicating more attention allocation to affectively incongruent prime-target pairs. N400 was insensitive to emotion. Response-locked ERPs revealed an early fronto-central negativity from 480ms before reactions to positive words. It was generated in both fronto-central and extra-striate visual areas, demonstrating a contribution of perceptual and, notably, motor preparation processes. Thus, no behavioural and little neural evidence for congruency-driven affective priming with emotional pictures was found, but positive stimuli generally facilitated lexical decisions, not only enhancing perception, but also acting rapidly on response preparation and by-passing full semantic analysis. Copyright © 2010 Elsevier B.V. All rights reserved.

Determination and characterization of the Hubble Space Telescope pointing stability

NASA Technical Reports Server (NTRS)

Bradley, A. J.; Connor, C. T.; Del Toro, Y.; Andersen, G. C.; Bely, Pierre Y.; Decker, J.; Franz, O. G.; Wasserman, L. H.; Van Altena, William F.

1993-01-01

The Hubble Space Telescope (HST) was designed to maintian a pointing stability (jitter) of 0.007 arc seconds rms throughout every observing period, which can last from a few seconds to several orbits. On-orbit measurements indicate that the hardware excitation induced by the reaction wheels. gyros, high gain antennae, science instrument mechanisms and tape recorders are well within specifications. Unexpectedly, the solar arrays because the dominant source of jitter. Every passage through an orbital terminator produces vibrations which emanate from the solar arrays due to thermal effects, which affect the relative positional stability. Broadband frequencies centered about 0.11 and 0.65 Hz were detected in the frequency content of the vehicle jitter. On-board modifications to the control law have attenuated the disturbance torques and reduced the vehicle jitter close to specification. Replacement of the solar arrays in December, 1993, should eliminate the torque distubances. Astrometric science observations are extremely susceptible to corruption from vehicle jitter. The removal of vehicle jitter from astrometric Transfer function scans of binary stars is explained in detail. A binary star separation of 16 milli-seconds of arc has been achieved, a separation resolution of 10 to 12 milli-seconds of arc appears feasible, with a binary star magnitude of 9 m(sub V). The achievement of this resolution is in part due to vehicle jitter removal. Comparison of vehicle jitter measurements from the position path of the vehicle control law, or from the guiding Fine Guidance Sensors (FGS), are shown to be equivalent to approximately 0.001 arc second.

Determination and characterization of the Hubble Space Telescope pointing stability

NASA Astrophysics Data System (ADS)

Bradley, A. J.; Connor, C. T.; del Toro, Y.; Andersen, G. C.; Bely, Pierre Y.; Decker, J.; Franz, O. G.; Wasserman, L. H.; van Altena, William F.

The Hubble Space Telescope (HST) was designed to maintian a pointing stability (jitter) of 0.007 arc seconds rms throughout every observing period, which can last from a few seconds to several orbits. On-orbit measurements indicate that the hardware excitation induced by the reaction wheels. gyros, high gain antennae, science instrument mechanisms and tape recorders are well within specifications. Unexpectedly, the solar arrays because the dominant source of jitter. Every passage through an orbital terminator produces vibrations which emanate from the solar arrays due to thermal effects, which affect the relative positional stability. Broadband frequencies centered about 0.11 and 0.65 Hz were detected in the frequency content of the vehicle jitter. On-board modifications to the control law have attenuated the disturbance torques and reduced the vehicle jitter close to specification. Replacement of the solar arrays in December, 1993, should eliminate the torque distubances. Astrometric science observations are extremely susceptible to corruption from vehicle jitter. The removal of vehicle jitter from astrometric Transfer function scans of binary stars is explained in detail. A binary star separation of 16 milli-seconds of arc has been achieved, a separation resolution of 10 to 12 milli-seconds of arc appears feasible, with a binary star magnitude of 9 m(sub V). The achievement of this resolution is in part due to vehicle jitter removal. Comparison of vehicle jitter measurements from the position path of the vehicle control law, or from the guiding Fine Guidance Sensors (FGS), are shown to be equivalent to approximately 0.001 arc second.

The Development and Evaluation of an Information Technology Support System to Facilitate Inter-Organisational Collaboration in HRD

ERIC Educational Resources Information Center

Ford, Norma J.

2006-01-01

Purpose: The purpose of this article is to evaluate the diffusion of and user response to an information technology support system (ITSS) which was designed to facilitate inter-organisational coordination and collaboration in the professional development of officers employed by local authorities (LAs). Design/methodology/approach: An action…

Facilitation of learning: part 1.

PubMed

Warburton, Tyler; Trish, Houghton; Barry, Debbie

2016-04-06

This article, the fourth in a series of 11, discusses the context for the facilitation of learning. It outlines the main principles and theories for understanding the process of learning, including examples which link these concepts to practice. The practical aspects of using these theories in a practice setting will be discussed in the fifth article of this series. Together, these two articles will provide mentors and practice teachers with knowledge of the learning process, which will enable them to meet the second domain of the Nursing and Midwifery Council's Standards to Support Learning and Assessment in Practice on facilitation of learning.

Stable statistical representations facilitate visual search.

PubMed

Corbett, Jennifer E; Melcher, David

2014-10-01

Observers represent the average properties of object ensembles even when they cannot identify individual elements. To investigate the functional role of ensemble statistics, we examined how modulating statistical stability affects visual search. We varied the mean and/or individual sizes of an array of Gabor patches while observers searched for a tilted target. In "stable" blocks, the mean and/or local sizes of the Gabors were constant over successive displays, whereas in "unstable" baseline blocks they changed from trial to trial. Although there was no relationship between the context and the spatial location of the target, observers found targets faster (as indexed by faster correct responses and fewer saccades) as the global mean size became stable over several displays. Building statistical stability also facilitated scanning the scene, as measured by larger saccadic amplitudes, faster saccadic reaction times, and shorter fixation durations. These findings suggest a central role for peripheral visual information, creating context to free resources for detailed processing of salient targets and maintaining the illusion of visual stability.

Climate warming may facilitate invasion of the exotic shrub Lantana camara.

PubMed

Zhang, Qiaoying; Zhang, Yunchun; Peng, Shaolin; Zobel, Kristjan

2014-01-01

Plant species show different responses to the elevated temperatures that are resulting from global climate change, depending on their ecological and physiological characteristics. The highly invasive shrub Lantana camara occurs between the latitudes of 35 °N and 35 °S. According to current and future climate scenarios predicted by the CLIMEX model, climatically suitable areas for L. camara are projected to contract globally, despite expansions in some areas. The objective of this study was to test those predictions, using a pot experiment in which branch cuttings were grown at three different temperatures (22 °C, 26 °C and 30 °C). We hypothesized that warming would facilitate the invasiveness of L. camara. In response to rising temperatures, the total biomass of L. camara did increase. Plants allocated more biomass to stems and enlarged their leaves more at 26 °C and 30 °C, which promoted light capture and assimilation. They did not appear to be stressed by higher temperatures, in fact photosynthesis and assimilation were enhanced. Using lettuce (Lactuca sativa) as a receptor plant in a bioassay experiment, we also tested the phytotoxicity of L. camara leachate at different temperatures. All aqueous extracts from fresh leaves significantly inhibited the germination and seedling growth of lettuce, and the allelopathic effects became stronger with increasing temperature. Our results provide key evidence that elevated temperature led to significant increases in growth along with physiological and allelopathic effects, which together indicate that global warming facilitates the invasion of L. camara.

Emotional eating and Pavlovian learning: does negative mood facilitate appetitive conditioning?

PubMed

Bongers, Peggy; van den Akker, Karolien; Havermans, Remco; Jansen, Anita

2015-06-01

Emotional eating has been suggested to be a learned behaviour; more specifically, classical conditioning processes might be involved in its development. In the present study we investigated whether a negative mood facilitates appetitive conditioning and whether trait impulsivity influences this process. After undergoing either a negative or neutral mood induction, participants were subjected to a differential classical conditioning procedure, using neutral stimuli and appetizing food. Two initially neutral distinctive vases with flowers were (CS+) or were not (CS-) paired with chocolate mousse intake. We measured participants' expectancy and desire to eat (4 CS+ and 4 CS- trials), salivation response, and actual food intake. The BIS-11 was administered to assess trait impulsivity. In both mood conditions, participants showed a classically conditioned appetite. Unexpectedly, there was no evidence of facilitated appetitive learning in a negative mood with regard to expectancy, desire, salivation, or intake. However, immediately before the taste test, participants in the negative mood condition reported a stronger desire to eat in the CS+ compared to the CS- condition, while no such effect occurred in the neutral group. An effect of impulsivity was found with regard to food intake in the neutral mood condition: high-impulsive participants consumed less food when presented with the CS+ compared to the CS-, and also less than low-impulsive participants. An alternative pathway to appetitive conditioning with regard to emotions is that it is not the neutral stimuli, but the emotions themselves that become conditioned stimuli and elicit appetitive responses. Copyright © 2015 Elsevier Ltd. All rights reserved.

Climate Warming May Facilitate Invasion of the Exotic Shrub Lantana camara

PubMed Central

Zhang, Qiaoying; Zhang, Yunchun; Peng, Shaolin; Zobel, Kristjan

2014-01-01

Plant species show different responses to the elevated temperatures that are resulting from global climate change, depending on their ecological and physiological characteristics. The highly invasive shrub Lantana camara occurs between the latitudes of 35°N and 35°S. According to current and future climate scenarios predicted by the CLIMEX model, climatically suitable areas for L. camara are projected to contract globally, despite expansions in some areas. The objective of this study was to test those predictions, using a pot experiment in which branch cuttings were grown at three different temperatures (22°C, 26°C and 30°C). We hypothesized that warming would facilitate the invasiveness of L. camara. In response to rising temperatures, the total biomass of L. camara did increase. Plants allocated more biomass to stems and enlarged their leaves more at 26°C and 30°C, which promoted light capture and assimilation. They did not appear to be stressed by higher temperatures, in fact photosynthesis and assimilation were enhanced. Using lettuce (Lactuca sativa) as a receptor plant in a bioassay experiment, we also tested the phytotoxicity of L. camara leachate at different temperatures. All aqueous extracts from fresh leaves significantly inhibited the germination and seedling growth of lettuce, and the allelopathic effects became stronger with increasing temperature. Our results provide key evidence that elevated temperature led to significant increases in growth along with physiological and allelopathic effects, which together indicate that global warming facilitates the invasion of L. camara. PMID:25184224

PKM2 released by neutrophils at wound site facilitates early wound healing by promoting angiogenesis.

PubMed

Zhang, Yinwei; Li, Liangwei; Liu, Yuan; Liu, Zhi-Ren

2016-03-01

Neutrophils infiltration/activation following wound induction marks the early inflammatory response in wound repair. However, the role of the infiltrated/activated neutrophils in tissue regeneration/proliferation during wound repair is not well understood. Here, we report that infiltrated/activated neutrophils at wound site release pyruvate kinase M2 (PKM2) by its secretive mechanisms during early stages of wound repair. The released extracellular PKM2 facilitates early wound healing by promoting angiogenesis at wound site. Our studies reveal a new and important molecular linker between the early inflammatory response and proliferation phase in tissue repair process. © 2016 by the Wound Healing Society.

Social facilitation of eating novel food in tufted capuchin monkeys (Cebus apella): input provided by group members and responses affected in the observer.

PubMed

Addessi, E; Visalberghi, E

2001-11-01

Learning about food palatability from watching what conspecifics eat might be one of the advantages of group living. A previous study investigated whether group members' presence or eating activity account for social facilitation of eating of foods never previously tasted. Capuchins encountered novel colored foods when (1) alone (Alone condition) or (2) with group members visible in the nearby cage (Group-present condition) or (3) with group members present and eating a familiar food that had not been colored (Group+food condition). Social facilitation of eating occurred when group members were eating, despite the difference in color between the familiar food eaten by them and the novel food presented to the experimental subject. To clarify what subjects learnt from group members when social facilitation occurred, we further analyze here the data from the previous study. The number of visual exposures to the colored novel food (as a group member) correlated with increased consumption of that novel food when encountered later (as experimental subject). In contrast, the number of times that an individual fed on the familiar food (as a group member) did not decrease its consumption of novel food (as experimental subject). Therefore, capuchins (1) habituated to the colors of the novel foods, and (2) did not take into account that seeing group members eating a food does not provide information about the palatability of a differently colored food. Since social facilitation of eating occurs when foods do not match in color, at least in capuchins, social facilitation of eating should not be considered as a way of learning about a safe diet, but rather as a way of overcoming neophobia.

Parent Involvement Facilitators: Unlocking Social Capital Wealth

ERIC Educational Resources Information Center

Ferrara, Margaret M.

2015-01-01

This case study provides an overview of a family outreach intervention that supports student retention in school through a school-home communication link. This intervention structure, which employs staff appropriately called parent involvement facilitators (PIFs), is one that school districts have employed to facilitate family engagement in…

Response deprivation, reinforcement, and economics

PubMed Central

Allison, James

1993-01-01

Reinforcement of an instrumental response results not from a special kind of response consequence known as a reinforcer, but from a special kind of schedule known as a response-deprivation schedule. Under the requirements of a response-deprivation schedule, the baseline rate of the instrumental response permits less than the baseline rate of the contingent response. Because reinforcement occurs only if the schedule deprives the organism of the contingent response, reinforcement cannot result from any intrinsic property of the contingent response or any property relative to the instrumental response. Two typical effects of response-deprivation schedules—facilitation of the instrumental response and suppression of the contingent response—are discussed in terms of economic concepts and models of instrumental performance. It is suggested that response deprivation makes the contingent response function as an economic good, the instrumental response as currency. PMID:16812695

Effects of ultraviolet-B irradiance on intraspecific competition and facilitation of plants: self-thinning, size inequality, and phenotypic plasticity.

PubMed

Zhang, Rui-Chang; Lin, Yue; Yue, Ming; Li, Qian; Zhang, Xiao-Fei; Liu, Xiao; Chi, Hong; Chai, Yong-Fu; Wang, Mao

2012-01-01

(1) The effects of facilitation on the structure and dynamics of plant populations have not been studied so widely as competition. The UV-B radiation, as a typical environmental factor causing stress, may result in direct stress and facilitation. (2) The effects of UV-B radiation on intraspecific competition and facilitation were investigated based on the following three predictions on self-thinning, size inequality, and phenotypic plasticity: i) Self-thinning is the reduction in density that results from the increase in the mean biomass of individuals in crowded populations, and is driven by competition. In this study, the mortality rate of the population is predicted to decrease from UV-B irradiance. ii) The size inequality of a population increases with competition intensity because larger individuals receive a disproportionate share of resources, thereby leaving limited resources for smaller individuals. The second hypothesis assumes that direct stress decreases the size inequality of the population. iii) Phenotypic plasticity is the ability to alter one's morphology in response to environmental changes. The third hypothesis assumes that certain morphological indices can change among the trade-offs between competition, facilitation, and stress. These predictions were tested by conducting a field pot experiment using mung beans, and were supported by the following results: (3) UV-B radiation increased the survival rate of the population at the end of self-thinning. However, this result was mainly due to direct stress rather than facilitation. (4) Just as competitor, facilitation was also asymmetric. It increased the size inequality of populations during self-thinning, whereas stress decreased the size inequality. (5) Direct stress and facilitation influence plants differently on various scales. Stress inhibited plant growth, whereas facilitation showed the opposite on an individual scale. Stress increased survival rate, whereas facilitation increased individual

Disturbance-mediated facilitation by an intertidal ecosystem engineer.

PubMed