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Sample records for distributed feedback effect

  1. Distributed Feedback Effects in Active Semiconductor Photonic Crystal Waveguides

    DEFF Research Database (Denmark)

    Chen, Yaohui; Mørk, Jesper

    2012-01-01

    We present a rigorous coupled-wave analysis of slow-light effects in active photonic crystal waveguides. The presence of active material leads to coherent distributed feedback effects that significantly alter the magnitude and phase of output fields.......We present a rigorous coupled-wave analysis of slow-light effects in active photonic crystal waveguides. The presence of active material leads to coherent distributed feedback effects that significantly alter the magnitude and phase of output fields....

  2. Spatial distribution effect of feedback reactivity in TRACY experiments. Evaluation of the first power peak characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Obara, Toru; Sekimoto, Hiroshi [Tokyo Inst. of Technology, Research Lab. for Nuclear Reactors, Tokyo (Japan); Nakajima, Ken; Miyoshi, Yoshinori [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-06-01

    To investigate the spatial effect of feedback reactivity in TRACY experiments, evaluations of the first power peak characteristics using the one-point reactor approximation model and a space dependent kinetics code, PCTAC, were conducted. Analyses for a core with uniform temperature distribution using the temperature feedback reactivity multiplied by a weight of 1.5 gave the same results as those for a core with space dependent power distribution. Neutronic calculations for spatial effect of temperature and space dependent kinetics analyses showed that the spatial effect of the temperature feedback reactivity at the peak power was dominated by the power distribution without feedback, and this resulted in a weight of 1.5. (author)

  3. Random distributed feedback fibre lasers

    Science.gov (United States)

    Turitsyn, Sergei K.; Babin, Sergey A.; Churkin, Dmitry V.; Vatnik, Ilya D.; Nikulin, Maxim; Podivilov, Evgenii V.

    2014-09-01

    The concept of random lasers exploiting multiple scattering of photons in an amplifying disordered medium in order to generate coherent light without a traditional laser resonator has attracted a great deal of attention in recent years. This research area lies at the interface of the fundamental theory of disordered systems and laser science. The idea was originally proposed in the context of astrophysics in the 1960s by V.S. Letokhov, who studied scattering with “negative absorption” of the interstellar molecular clouds. Research on random lasers has since developed into a mature experimental and theoretical field. A simple design of such lasers would be promising for potential applications. However, in traditional random lasers the properties of the output radiation are typically characterized by complex features in the spatial, spectral and time domains, making them less attractive than standard laser systems in terms of practical applications. Recently, an interesting and novel type of one-dimensional random laser that operates in a conventional telecommunication fibre without any pre-designed resonator mirrors-random distributed feedback fibre laser-was demonstrated. The positive feedback required for laser generation in random fibre lasers is provided by the Rayleigh scattering from the inhomogeneities of the refractive index that are naturally present in silica glass. In the proposed laser concept, the randomly backscattered light is amplified through the Raman effect, providing distributed gain over distances up to 100 km. Although an effective reflection due to the Rayleigh scattering is extremely small (˜0.1%), the lasing threshold may be exceeded when a sufficiently large distributed Raman gain is provided. Such a random distributed feedback fibre laser has a number of interesting and attractive features. The fibre waveguide geometry provides transverse confinement, and effectively one-dimensional random distributed feedback leads to the generation

  4. Random distributed feedback fibre lasers

    Energy Technology Data Exchange (ETDEWEB)

    Turitsyn, Sergei K., E-mail: s.k.turitsyn@aston.ac.uk [Aston Institute of Photonic Technologies, Aston University, Birmingham B4 7ET (United Kingdom); Novosibirsk State University, 2 Pirogova str., 630090, Novosibirsk (Russian Federation); Babin, Sergey A. [Novosibirsk State University, 2 Pirogova str., 630090, Novosibirsk (Russian Federation); Institute of Automation and Electrometry SB RAS, 1 Ac. Koptug. ave., 630090, Novosibirsk (Russian Federation); Churkin, Dmitry V. [Aston Institute of Photonic Technologies, Aston University, Birmingham B4 7ET (United Kingdom); Novosibirsk State University, 2 Pirogova str., 630090, Novosibirsk (Russian Federation); Institute of Automation and Electrometry SB RAS, 1 Ac. Koptug. ave., 630090, Novosibirsk (Russian Federation); Vatnik, Ilya D.; Nikulin, Maxim [Institute of Automation and Electrometry SB RAS, 1 Ac. Koptug. ave., 630090, Novosibirsk (Russian Federation); Podivilov, Evgenii V. [Novosibirsk State University, 2 Pirogova str., 630090, Novosibirsk (Russian Federation); Institute of Automation and Electrometry SB RAS, 1 Ac. Koptug. ave., 630090, Novosibirsk (Russian Federation)

    2014-09-10

    The concept of random lasers exploiting multiple scattering of photons in an amplifying disordered medium in order to generate coherent light without a traditional laser resonator has attracted a great deal of attention in recent years. This research area lies at the interface of the fundamental theory of disordered systems and laser science. The idea was originally proposed in the context of astrophysics in the 1960s by V.S. Letokhov, who studied scattering with “negative absorption” of the interstellar molecular clouds. Research on random lasers has since developed into a mature experimental and theoretical field. A simple design of such lasers would be promising for potential applications. However, in traditional random lasers the properties of the output radiation are typically characterized by complex features in the spatial, spectral and time domains, making them less attractive than standard laser systems in terms of practical applications. Recently, an interesting and novel type of one-dimensional random laser that operates in a conventional telecommunication fibre without any pre-designed resonator mirrors–random distributed feedback fibre laser–was demonstrated. The positive feedback required for laser generation in random fibre lasers is provided by the Rayleigh scattering from the inhomogeneities of the refractive index that are naturally present in silica glass. In the proposed laser concept, the randomly backscattered light is amplified through the Raman effect, providing distributed gain over distances up to 100 km. Although an effective reflection due to the Rayleigh scattering is extremely small (∼0.1%), the lasing threshold may be exceeded when a sufficiently large distributed Raman gain is provided. Such a random distributed feedback fibre laser has a number of interesting and attractive features. The fibre waveguide geometry provides transverse confinement, and effectively one-dimensional random distributed feedback leads to the

  5. The effect of pulsewidth of pumping pulse on the stability of distributed feedback dye laser

    Science.gov (United States)

    Pasandideh, K.; Rahbari, M.; Sadighi Bonabi, R.

    2017-04-01

    The generation of a single and stable picosecond pulse by distributed feedback dye laser is investigated in this work. The numerical result for the rate equation system that includes the thermal effects in the lasing medium is provided. By applying this model to Rhodamine 6G, it is found that considerable improvement in the stability of the laser can be achieved by pumping the system with narrower laser pulses. The simulation shows that if the dye solution is pumped by sub-200 ps pulse, the laser can be operated in single-pulse output mode with acceptable stability in pulsewidth over a long range of pumping intensity. This result is confirmed by a more complicated model composed of non-averaged Maxwell and rate equations. Even though the thermal effects do not play a significant role in equivalent cavity lifetime, they result in considerable wavelength shift toward the shorter wavelengths.

  6. Numerical Analysis of SHB Effects in Laterally-Coupled Distributed Feedback (LC-DFB Lasers

    Directory of Open Access Journals (Sweden)

    M. Seifouri

    2012-10-01

    Full Text Available In this paper the stability of Laterally-Coupled Distributed Feedback (LC-DFB Lasers against the Spatial Hole Burning (SHB effect is analyzed theoretically. The stability of the laser structure is evaluated using the flatness parameter F. It is shown that the LC-DFB lasers are stable in a wide range of different values ​​of ridge width and amplitude grating. The stability is sustained with increasing injection current. The results show that the flatness parameter is minimal for certain values ​​of the amplitude grating. The numerical calculations have been done by coupled wave and carrier rate equations on the basis of the transfer matrix method (TMM.

  7. Immediate Feedback on Accuracy and Performance: The Effects of Wireless Technology on Food Safety Tracking at a Distribution Center

    Science.gov (United States)

    Goomas, David T.

    2012-01-01

    The effects of wireless ring scanners, which provided immediate auditory and visual feedback, were evaluated to increase the performance and accuracy of order selectors at a meat distribution center. The scanners not only increased performance and accuracy compared to paper pick sheets, but were also instrumental in immediate and accurate data…

  8. Physics of Galactic Metals: Evolutionary Effects due to Production, Distribution, Feedback & Interaction with Black Holes

    CERN Document Server

    Choi, Ena; Naab, Thorsten; Somerville, Rachel S; Hirschmann, Michaela; Núñez, Alejandro; Hu, Chia-Yu; Oser, Ludwig

    2016-01-01

    We ask how the inclusion of various physical heating processes due to the metal content of gas affect the evolution of massive galaxies and compute a suite of cosmological hydrodynamical simulations that follow these systems and their supermassive black holes. We use a smoothed particle hydrodynamics code with a pressure-entropy formulation and a more accurate treatment of the metal production, turbulent diffusion and cooling rate based on individual element abundances. The feedback models include (1) AGN feedback via high velocity BAL winds and Compton/photoionization heating, (2) explicit stellar feedback from multiple processes including powerful winds from supernova events, stellar winds from young massive stars and AGB stars as well as radiative heating within Stromgren spheres around massive stars, and (3) additional heating effects due to the presence of metals including grain photoelectric heating, metallicity dependent X-ray heating by nearby accreting black holes and from the cosmic X-ray background...

  9. Fine Distributed Moderating Material with Improved Thermal Stability Applied to Enhance the Feedback Effects in SFR Cores

    Directory of Open Access Journals (Sweden)

    Bruno Merk

    2013-01-01

    Full Text Available The use of fine distributed moderating material to enhance the feedback effects and to reduce the sodium void effect in sodium-cooled fast reactor cores is described. The influence of the moderating material on the fuel assembly geometry, the neutron spectrum, the feedback effects, the power and burnup distribution, and the transmutation performance is given. An overview on possible materials is provided and the relationship between hydrogen content and thermal stability is described. A solution for the problem of the limited thermal stability of primarily proposed hydrogen-bearing moderating material ZrH1.6 is developed by the use of yttrium-mono-hydride. The similarity in the effects reached by ZrH and YH is demonstrated by comparison calculations. The topic is closed by an overview on material properties, manufacturing issues, experience in fast reactors, and a comparison of raw material costs.

  10. Strategies for effective feedback.

    Science.gov (United States)

    Kritek, Patricia A

    2015-04-01

    Provision of regular feedback to trainees on clinical performance by supervising providers is increasingly recognized as an essential component of undergraduate and graduate health sciences education; however, many individuals have not been formally trained in this pedagogical skill. At the bedside or in the clinic, effective performance feedback can be accomplished by following four key steps. Begin by setting expectations that incorporate the trainee's personal goals and external objectives. Delineate how and when you will provide feedback to the learner. Next, directly observe the trainee's performance. This can be challenging while engaged on a busy clinical service, but a focus on discrete activities or interactions (e.g., family meeting, intravascular volume assessment using bedside ultrasound, or obtaining informed consent) is helpful. The third step is to plan and prioritize the feedback session. Feedback is most effective when given in a timely fashion and delivered in a safe environment. Limit the issues addressed because learners often disengage if confronted with too many deficiencies. Finally, when delivering feedback, begin by listening to the trainee's self-evaluation and then take a balanced approach. Describe in detail what the trainee does well and discuss opportunities for improvement with emphasis on specific, modifiable behaviors. The feedback loop is completed with a plan for follow-up reassessment. Through the use of these relatively simple practices, both the trainee and teacher can have a more productive learning experience.

  11. The effects of baryon physics, black holes and AGN feedback on the mass distribution in clusters of galaxies

    CERN Document Server

    Martizzi, Davide; Moore, Ben; Wentz, Tina

    2011-01-01

    The spatial distribution of matter in clusters of galaxies is mainly determined by the dominant dark matter component, however, physical processes involving baryonic matter are able to modify it significantly. We analyse a set of 500 pc resolution cosmological simulations of a cluster of galaxy with mass comparable to Virgo, performed with the AMR code RAMSES. We compare the mass density profiles of the dark, stellar and gaseous matter components of the cluster that result from different assumptions for the subgrid baryonic physics and galaxy formation processes. First, the prediction of a gravity only N-body simulation is compared to that of a hydrodynamical simulation with standard galaxy formation recipes, then all results are compared to a hydrodynamical simulation which includes thermal AGN feedback from Super Massive Black Holes (SMBH). We find the usual effects of overcooling and adiabatic contraction in the run with standard galaxy formation physics, but very different results are found when implement...

  12. The effects of baryon physics, black holes and active galactic nucleus feedback on the mass distribution in clusters of galaxies

    Science.gov (United States)

    Martizzi, Davide; Teyssier, Romain; Moore, Ben; Wentz, Tina

    2012-06-01

    The spatial distribution of matter in clusters of galaxies is mainly determined by the dominant dark matter component; however, physical processes involving baryonic matter are able to modify it significantly. We analyse a set of 500 pc resolution cosmological simulations of a cluster of galaxies with mass comparable to Virgo, performed with the AMR code RAMSES. We compare the mass density profiles of the dark, stellar and gaseous matter components of the cluster that result from different assumptions for the subgrid baryonic physics and galaxy formation processes. First, the prediction of a gravity-only N-body simulation is compared to that of a hydrodynamical simulation with standard galaxy formation recipes, and then all results are compared to a hydrodynamical simulation which includes thermal active galactic nucleus (AGN) feedback from supermassive black holes (SMBHs). We find the usual effects of overcooling and adiabatic contraction in the run with standard galaxy formation physics, but very different results are found when implementing SMBHs and AGN feedback. Star formation is strongly quenched, producing lower stellar densities throughout the cluster, and much less cold gas is available for star formation at low redshifts. At redshift z= 0 we find a flat density core of radius 10 kpc in both the dark and stellar matter density profiles. We speculate on the possible formation mechanisms able to produce such cores and we conclude that they can be produced through the coupling of different processes: (I) dynamical friction from the decay of black hole orbits during galaxy mergers; (II) AGN-driven gas outflows producing fluctuations of the gravitational potential causing the removal of collisionless matter from the central region of the cluster; (III) adiabatic expansion in response to the slow expulsion of gas from the central region of the cluster during the quiescent mode of AGN activity.

  13. Distributed Beamforming with Feedback: Convergence Analysis

    CERN Document Server

    Lin, C; Meyn, S

    2008-01-01

    The focus of this work is on the analysis of transmit beamforming schemes with a low-rate feedback link in wireless sensor/relay networks, where nodes in the network need to implement beamforming in a distributed manner. Specifically, the problem of distributed phase alignment is considered, where neither the transmitters nor the receiver has perfect channel state information, but there is a low-rate feedback link from the receiver to the transmitters. In this setting, a framework for systematically analyzing the performance of a general set of distributed beamforming schemes is proposed. To illustrate the advantage of this framework, a simple adaptive distributed beamforming scheme that was recently proposed by Mudambai et al. is studied. Two important properties for the received signal magnitude function are derived. Using these properties and the systematic framework, it is shown that the adaptive distributed beamforming scheme converges both in probability and in mean. Furthermore, it is established that ...

  14. Single-mode biological distributed feedback laser

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Maier-Flaig, Florian; Lemmer, Uli

    2013-01-01

    Single-mode second order distributed feedback (DFB) lasers of riboflavin (vitamin B2) doped gelatine films on nanostructured low refractive index material are demonstrated. Manufacturing is based on a simple UV nanoimprint and spin-coating. Emission wavelengths of 543 nm and 562 nm for two...

  15. The effect of host star spectral energy distribution and ice-albedo feedback on the climate of extrasolar planets.

    Science.gov (United States)

    Shields, Aomawa L; Meadows, Victoria S; Bitz, Cecilia M; Pierrehumbert, Raymond T; Joshi, Manoj M; Robinson, Tyler D

    2013-08-01

    Planetary climate can be affected by the interaction of the host star spectral energy distribution with the wavelength-dependent reflectivity of ice and snow. In this study, we explored this effect with a one-dimensional (1-D), line-by-line, radiative transfer model to calculate broadband planetary albedos as input to a seasonally varying, 1-D energy balance climate model. A three-dimensional (3-D) general circulation model was also used to explore the atmosphere's response to changes in incoming stellar radiation, or instellation, and surface albedo. Using this hierarchy of models, we simulated planets covered by ocean, land, and water-ice of varying grain size, with incident radiation from stars of different spectral types. Terrestrial planets orbiting stars with higher near-UV radiation exhibited a stronger ice-albedo feedback. We found that ice extent was much greater on a planet orbiting an F-dwarf star than on a planet orbiting a G-dwarf star at an equivalent flux distance, and that ice-covered conditions occurred on an F-dwarf planet with only a 2% reduction in instellation relative to the present instellation on Earth, assuming fixed CO(2) (present atmospheric level on Earth). A similar planet orbiting the Sun at an equivalent flux distance required an 8% reduction in instellation, while a planet orbiting an M-dwarf star required an additional 19% reduction in instellation to become ice-covered, equivalent to 73% of the modern solar constant. The reduction in instellation must be larger for planets orbiting cooler stars due in large part to the stronger absorption of longer-wavelength radiation by icy surfaces on these planets in addition to stronger absorption by water vapor and CO(2) in their atmospheres, which provides increased downwelling longwave radiation. Lowering the IR and visible-band surface ice and snow albedos for an M-dwarf planet increased the planet's climate stability against changes in instellation and slowed the descent into global ice

  16. Ultra-wideband signal generator based on cross gain modulation effect in a distributed feedback laser

    Science.gov (United States)

    Chen, Dalei; Wang, Rong; Xiang, Peng; Pu, Tao; Fang, Tao; Li, Yuandong; Su, Yang; Zheng, Jiling; Huang, Long; Zhu, Huatao; Huang, Jie

    2016-10-01

    In this paper, a novel scheme to generate ultra-wideband (UWB) signals based on cross-gain modulation (XGM) effect in a DFB laser is proposed and experimentally demonstrated, and the modulation and transmission of the UWB signals are also experimentally investigated. In the proposed system, a gain-switched laser (GSL) is used as master laser (ML) and the optical pulses from the ML are optically injected into a DFB laser, which is used as slave laser (SL). By proper system configuration, UWB monocycle, doublet or triplet UWB signals can be generated after the balanced photodiode (BPD) detection. Besides, other modulation formats can also be realized, such as on-off keying (OOK) and pulse amplitude modulation (PAM) by properly modulating the ML optical pulses. Finally, fiber transmission of the modulated UWB signals is experimentally investigated, and it is shown that the UWB signals can be well maintained after 40 km optical fiber transmission.

  17. The Effect of Host Star Spectral Energy Distribution and Ice-Albedo Feedback on the Climate of Extrasolar Planets

    CERN Document Server

    Shields, Aomawa L; Bitz, Cecilia M; Pierrehumbert, Raymond T; Joshi, Manoj M; Robinson, Tyler D

    2013-01-01

    Planetary climate can be affected by the interaction of the host star spectral energy distribution with the wavelength-dependent reflectivity of ice and snow. Here we explore this effect using a one dimensional (1-D), line-by-line, radiative-transfer model to calculate broadband planetary albedos as input to a seasonally varying, 1-D energy-balance climate model. A three-dimensional general circulation model is also used to explore the atmosphere's response to changes in incoming stellar radiation, or instellation, and surface albedo. Using this hierarchy of models we simulate planets covered by ocean, land, and water ice of varying grain size, with incident radiation from stars of different spectral types. Terrestrial planets orbiting stars with higher near-UV radiation exhibit a stronger ice-albedo feedback. We find that ice-covered conditions occur on an F-dwarf planet with only a 2% reduction in instellation relative to the present instellation on Earth, assuming fixed CO2 (present atmospheric level on Ea...

  18. Distributed Feedback Lasing with Cold Atoms

    CERN Document Server

    Schilke, Alexander; Courteille, Philippe W; Guerin, William

    2011-01-01

    There is currently a strong interest in mirrorless lasing. In these systems, the electromagnetic feedback is provided either by disorder, i.e., multiple scattering in the gain medium itself, or by order, i.e., multiple Bragg reflection. This corresponds, respectively, to "random lasers" and "photonic crystal lasers". The crossover regime, between order and disorder, or correlated disorder, starts also to be fruitfully investigated. Here, we report one-dimensional photonic crystal lasing, i.e., distributed feedback lasing, with a cold atom cloud that provides simultaneously both gain and feedback. The atoms are trapped in a 1D lattice, giving a density modulation that creates a strong Bragg reflection under a small angle of incidence. Pumping the atoms with auxiliary beams induces four wave mixing that provides gain. The combination of both ingredients generates a mirrorless laser with a conical output emission, whose apex angle is tunable with the lattice periodicity through the Bragg condition.

  19. Distributed Wireless Power Transfer With Energy Feedback

    Science.gov (United States)

    Lee, Seunghyun; Zhang, Rui

    2017-04-01

    Energy beamforming (EB) is a key technique for achieving efficient radio-frequency (RF) transmission enabled wireless energy transfer (WET). By optimally designing the waveforms from multiple energy transmitters (ETs) over the wireless channels, they can be constructively combined at the energy receiver (ER) to achieve an EB gain that scales with the number of ETs. However, the optimal design of EB waveforms requires accurate channel state information (CSI) at the ETs, which is challenging to obtain practically, especially in a distributed system with ETs at separate locations. In this paper, we study practical and efficient channel training methods to achieve optimal EB in a distributed WET system. We propose two protocols with and without centralized coordination, respectively, where distributed ETs either sequentially or in parallel adapt their transmit phases based on a low-complexity energy feedback from the ER. The energy feedback only depends on the received power level at the ER, where each feedback indicates one particular transmit phase that results in the maximum harvested power over a set of previously used phases. Simulation results show that the two proposed training protocols converge very fast in practical WET systems even with a large number of distributed ETs, while the protocol with sequential ET phase adaptation is also analytically shown to converge to the optimal EB design with perfect CSI by increasing the training time. Numerical results are also provided to evaluate the performance of the proposed distributed EB and training designs as compared to other benchmark schemes.

  20. Distributed feedback imprinted electrospun fiber lasers.

    Science.gov (United States)

    Persano, Luana; Camposeo, Andrea; Del Carro, Pompilio; Fasano, Vito; Moffa, Maria; Manco, Rita; D'Agostino, Stefania; Pisignano, Dario

    2014-10-01

    Imprinted, distributed feedback lasers are demonstrated on individual, active electrospun polymer nanofibers. In addition to advantages related to miniaturization, optical confinement and grating nanopatterning lead to a significant threshold reduction compared to conventional thin-film lasers. The possibility of imprinting arbitrary photonic crystal geometries on electrospun lasing nanofibers opens new opportunities for realizing optical circuits and chips. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Analysis of SAW distributed feedback resonators

    Science.gov (United States)

    Vandewege, J.; Lagasse, P. E.

    1981-01-01

    The main characteristics and advantages of the surface acoustic wave (SAW) distributed feedback resonator are discussed. A coupled mode analysis provides physical insight and simple formulas for the resonant frequency, the quality factor, and the input impedance. Those results are verified by means of a transmission line computer model and by a number of measurements in the frequency range 30-250 MHz. On YZ LiNbO3 substrates, quality factors of the order of 5,000 are routinely obtained.

  2. The Effect of Host Star Spectral Energy Distribution and Ice-Albedo Feedback on the Climate of Extrasolar Planets

    Science.gov (United States)

    Shields, Aomawa; Meadows, V.; Bitz, C. M.; Pierrehumbert, R. T.; Joshi, M. M.; Robinson, T. D.

    2013-01-01

    Planetary climate can be affected by the interaction of the host star spectral energy distribution with the wavelength-dependent reflectivity of ice and snow. A one dimensional (1-D), line-by-line, radiative-transfer model is used to calculate broadband planetary albedos as input to a seasonally varying, 1-D energy-balance climate model. We simulated planets covered by ocean, land, and water ice of varying grain size, with incident radiation from stars of different spectral types. Our results show that terrestrial planets orbiting stars with higher near-UV radiation exhibit a stronger ice-albedo feedback. Using a general circulation model we demonstrate that an ocean-covered planet orbiting in the habitable zone of an M-dwarf star has a higher global mean surface temperature than a planet orbiting the Sun (a G-dwarf star) at an equivalent stellar flux distance. The effect is even more pronounced when the albedos of snow and ice are lowered, indicating the importance of the spectral dependence of surface ice and snow on climate for these planets. We find that the sensitivity of climate to changes in stellar insolation for M-dwarf planets is weaker than for planets orbiting stars with greater visible and near-UV radiation. While a planet orbiting the Sun becomes ice-covered with an 8% reduction in stellar insolation, a similar planet orbiting an M dwarf requires a 27% reduction to become ice-covered. A 2% reduction in stellar insolation is all that is required for global ice cover on a planet orbiting an F-dwarf star. Consequently the habitable zone for surface liquid water on planets with Earth-like greenhouse gas concentrations may be ~12% wider for M-dwarf stars than for G-dwarf stars, and ~3% narrower for F-dwarf stars. Higher obliquities expand the outer habitable zone boundary for surface liquid water. Raising atmospheric CO2 can reduce the ice-albedo effect on M-dwarf planets, but ~3-10 bars are required to entirely mask the climatic effect of ice and snow.

  3. Feedback and rewards, Part I: Introduction to effective feedback.

    Science.gov (United States)

    Harolds, Jay A

    2013-01-01

    This series of articles discusses conversations regarding feedback. Feedback can include input from numerous sources, including one's supervisor, peers, subordinates, suppliers, customers, patients, and/or society members. Effective feedback is very important to the operation of any organization and to the growth of the individual. However, feedback done poorly does not appear to be rare and can be highly destructive to all. A variety of tips on how to do feedback well are included in this article.

  4. Tunability of optofluidic distributed feedback dye lasers

    DEFF Research Database (Denmark)

    Gersborg-Hansen, Morten; Kristensen, Anders

    2007-01-01

    We investigate the tunability of optofluidic distributed feedback (DFB) dye lasers. The lasers rely on light-confinement in a nano-structured polymer film where an array of nanofluidic channels constitutes a third order Bragg grating DFB laser resonator with a central phase-shift. The lasers...... are operated by filling the DFB laser resonator with a dye solution by capillary action and optical pumping with a frequency doubled Nd: YAG laser. The low reflection order of the DFB laser resonator yields low out-of-plane scattering losses as well as a large free spectral range (FSR), and low threshold...

  5. Optofluidic third order distributed feedback dye laser

    DEFF Research Database (Denmark)

    Gersborg-Hansen, Morten; Kristensen, Anders

    2006-01-01

    This letter describes the design and operation of a polymer-based third order distributed feedback (DFB) microfluidic dye laser. The device relies on light confinement in a nanostructured polymer film where an array of nanofluidic channels is filled by capillary action with a liquid dye solution...... which has a refractive index lower than that of the polymer. In combination with a third order DFB grating, formed by the array of nanofluidic channels, this yields a low threshold for lasing. The laser is straightforward to integrate on lab-on-a-chip microsystems where coherent, tunable light...

  6. Thulium distributed-feedback fiber lasers

    DEFF Research Database (Denmark)

    Agger, Søren Dyøe

    2006-01-01

    in silica and the fabri- cation, design and characterization of coherent Distributed Feed-Back (DFB) ber lasers incorporating thulium as the active laser medium. Our recent results have proved that single-frequency, single-polarization, narrow-linewidth (tens of kHz) operation of thulium doped DFB ber...... lasers is possible. Demonstrations of single-frequency lasers have, until now, been achieved at 1740 nm, 1984 nm and at a record-breaking 2090 nm. The 1740 nm laser has been boosted to 60 mW of output power with a linewidth of only 3 kHz and implemented in a plug-and-play turnkey system with SMF28-APC...

  7. Plasmonic distributed feedback lasers at telecommunications wavelengths.

    Science.gov (United States)

    Marell, Milan J H; Smalbrugge, Barry; Geluk, Erik Jan; van Veldhoven, Peter J; Barcones, Beatrix; Koopmans, Bert; Nötzel, Richard; Smit, Meint K; Hill, Martin T

    2011-08-01

    We investigate electrically pumped, distributed feedback (DFB) lasers, based on gap-plasmon mode metallic waveguides. The waveguides have nano-scale widths below the diffraction limit and incorporate vertical groove Bragg gratings. These metallic Bragg gratings provide a broad bandwidth stop band (~500 nm) with grating coupling coefficients of over 5000/cm. A strong suppression of spontaneous emission occurs in these Bragg grating cavities, over the stop band frequencies. This strong suppression manifests itself in our experimental results as a near absence of spontaneous emission and significantly reduced lasing thresholds when compared to similar length Fabry-Pérot waveguide cavities. Furthermore, the reduced threshold pumping requirements permits us to show strong line narrowing and super linear light current curves for these plasmon mode devices even at room temperature.

  8. Feedback, Incentives and Peer Effects

    DEFF Research Database (Denmark)

    Eriksson, Tor Viking; Poulsen, Anders; Villeval, Marie Claire

    effects in the piece-rate pay scheme. In both pay schemes, interim feedback generates negative quality peer effects on the less able performers. We find however evidence of positive peer effects in the tournament scheme since the underdogs almost never quit the competition even when lagging significantly...

  9. Evaluative Feedback: Perspectives on Media Effects

    National Research Council Canada - National Science Library

    Watts, Stephanie A

    2007-01-01

    .... No feedback effectiveness differences were found between media conditions, although determinants of feedback effectiveness differed significantly depending on the medium. These results are generally consistent with the theoretical model.

  10. Emission wavelength of multilayer distributed feedback dye lasers

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Smith, Cameron L. C.; Brøkner Christiansen, Mads;

    2012-01-01

    Precise emission wavelength modeling is essential for understanding and optimization of distributed feedback (DFB) lasers. An analytical approach for determining the emission wavelength based on setting the propagation constant of the Bragg condition and solving for the resulting slab waveguide...

  11. Effectiveness of Feedback in First Year Physics

    DEFF Research Database (Denmark)

    Bearden, Ian; Voigt, Karen A; Mathiasen, Helle

    How can we provide better and more effective feedback to our students? How can we encourage students to use feedback effectively? We will present results of a study of first year physics students addressing these questions and comparing the effectiveness of written and screencast feedback....

  12. Suboptimal distributed Kalman filtering fusion with feedback

    Institute of Scientific and Technical Information of China (English)

    Zhao Minhua; Zhu Zhuanmin; Shi Meng; Peng Qinke; Huang Yongxuan

    2005-01-01

    In order to improve the accuracy of fusion algorithm, feedback is introduced into Kalman filtering fusion. Fusion center broadcasts its latest estimated states to the local sensors, which can improve the performance of local tracking error through reducing the covariance of each local error, and only needs calculating the trace of error variance matrices without calculating the inverse of error variance matrices. Simulation results show that it can reduce the computational complexity and the covariance of error, and it is convenient for engineering applications.

  13. Multisensor Distributed Track Fusion AlgorithmBased on Strong Tracking Filter and Feedback Integration1)

    Institute of Scientific and Technical Information of China (English)

    YANGGuo-Sheng; WENCheng-Lin; TANMin

    2004-01-01

    A new multisensor distributed track fusion algorithm is put forward based on combiningthe feedback integration with the strong tracking Kalman filter. Firstly, an effective tracking gateis constructed by taking the intersection of the tracking gates formed before and after feedback.Secondly, on the basis of the constructed effective tracking gate, probabilistic data association andstrong tracking Kalman filter are combined to form the new multisensor distributed track fusionalgorithm. At last, simulation is performed on the original algorithm and the algorithm presented.

  14. Effects of Quasar Feedback in Galaxy Groups

    CERN Document Server

    Bhattacharya, Suman; Kosowsky, Arthur

    2007-01-01

    We study the effect of quasar feedback on distributions of baryons in galaxy groups using high-resolution numerical simulations. We use the entropy-conserving Gadget code that includes gas cooling and star formation, modified to include a physically-based model of quasar feedback. For a sample of ten galaxy group-sized dark matter halos with masses in the range of 1 to $5\\times 10^{13} M_{\\odot}/h$, star formation is suppressed by more than 30% in the inner regions due to the additional pressure support by quasar feedback, while gas is driven from the inner region towards the outer region of the halos. As a result, the average gas density is 20% lower in the inner region and 10% higher in the outer region in the simulation, compared to a similar simulation with no quasar feedback. Gas pressure is also higher in the outer region, while temperature and entropy are enhanced in the inner region. The total group gas fraction in the two simulations generally differs by less than 10%. We also find a small enhancemen...

  15. Giving Feedback: Development of Scales for the Mum Effect, Discomfort Giving Feedback, and Feedback Medium Preference

    Science.gov (United States)

    Cox, Susie S.; Marler, Laura E.; Simmering, Marcia J.; Totten, Jeff W.

    2011-01-01

    Research in organizational behavior and human resources promotes the view that it is critical for managers to provide accurate feedback to employees, yet little research addresses rater tendencies (i.e., the "mum effect") and attitudes that influence how performance feedback is given. Because technology has changed the nature of communication in…

  16. Design of distributed feedback fibre lasers

    DEFF Research Database (Denmark)

    Lauridsen, Vibeke Claudia; Søndergaard, Thomas; Varming, Poul

    1997-01-01

    A numerical model for erbium fibre lasers with Bragg gratings is presented. The model is used to optimize the location of a discrete phase-shift and the phase-shift magnitude for a distributed phase-shift.......A numerical model for erbium fibre lasers with Bragg gratings is presented. The model is used to optimize the location of a discrete phase-shift and the phase-shift magnitude for a distributed phase-shift....

  17. Single-Mode, Distributed Feedback Interband Cascade Lasers

    Science.gov (United States)

    Frez, Clifford F. (Inventor); Borgentun, Carl E. (Inventor); Briggs, Ryan M. (Inventor); Bagheri, Mahmood (Inventor); Forouhar, Siamak (Inventor)

    2016-01-01

    Single-mode, distributed feedback interband cascade lasers (ICLs) using distributed-feedback gratings (e.g., lateral Bragg gratings) and methods of fabricating such ICLs are provided. The ICLs incorporate distributed-feedback gratings that are formed above the laser active region and adjacent the ridge waveguide (RWG) of the ICL. The ICLs may incorporate a double-ridge system comprising an optical confinement structure (e.g., a RWG) disposed above the laser active region that comprises the first ridge of the double ridge system, a DFB grating (e.g., lateral Bragg grating) disposed above the laser active region and adjacent the optical confinement structure, and an electric confinement structure that passes at least partially through the laser active region and that defines the boundary of the second ridge comprises and the termination of the DFB grating.

  18. Event-triggered output feedback control for distributed networked systems.

    Science.gov (United States)

    Mahmoud, Magdi S; Sabih, Muhammad; Elshafei, Moustafa

    2016-01-01

    This paper addresses the problem of output-feedback communication and control with event-triggered framework in the context of distributed networked control systems. The design problem of the event-triggered output-feedback control is proposed as a linear matrix inequality (LMI) feasibility problem. The scheme is developed for the distributed system where only partial states are available. In this scheme, a subsystem uses local observers and share its information to its neighbors only when the subsystem's local error exceeds a specified threshold. The developed method is illustrated by using a coupled cart example from the literature.

  19. Effectiveness of Corrective Feedback on Writing

    Institute of Scientific and Technical Information of China (English)

    高砚

    2012-01-01

      This study aims to find out the effectiveness of corrective feedback on ESL writing. By reviewing and analyzing the previous six research studies, the author tries to reveal the most effective way to provide corrective feedback for L2 students and the factors that impact the processing of error feedback. Findings indicated that corrective feedback is helpful for students to improve ESL writing on both accuracy and fluency. Furthermore, correction and direct corrective feedbacks as well as the oral and written meta-linguistic explanation are the most effective ways to help students improving their writing. However, in⁃dividual learner’s difference has influence on processing corrective feedback. At last, limitation of present study and suggestion for future research were made.

  20. An Emerging Model for Student Feedback: Electronic Distributed Evaluation

    Science.gov (United States)

    Brunk-Chavez, Beth; Arrigucci, Annette

    2012-01-01

    In this article we address several issues and challenges that the evaluation of writing presents individual instructors and composition programs as a whole. We present electronic distributed evaluation, or EDE, as an emerging model for feedback on student writing and describe how it was integrated into our program's course redesign. Because the…

  1. Multilayer Slab Waveguide Distributed Feedback Dye Laser Sensors

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Smith, Cameron; Leung, M.

    2013-01-01

    Organic dye-based distributed feedback (DFB) lasers are widely tunable laser light sources in the visible wavelength range and exhibit low-cost, simple fabrication, low threshold and single-mode emission [1]. Precise emission wavelength modeling is essential for understanding and optimization of ...

  2. Distributed User Selection in Network MIMO Systems with Limited Feedback

    KAUST Repository

    Elkhalil, Khalil

    2015-09-06

    We propose a distributed user selection strategy in a network MIMO setting with M base stations serving K users. Each base station is equipped with L antennas, where LM ≪ K. The conventional selection strategy is based on a well known technique called semi-orthogonal user selection when the zero-forcing beamforming (ZFBF) is adopted. Such technique, however, requires perfect channel state information at the transmitter (CSIT), which might not be available or need large feedback overhead. This paper proposes an alternative distributed user selection technique where each user sets a timer that is inversely proportional to his channel quality indicator (CQI), as a means to reduce the feedback overhead. The proposed strategy allows only the user with the highest CQI to respond with a feedback. Such technique, however, remains collision free only if the transmission time is shorter than the difference between the strongest user timer and the second strongest user timer. To overcome the situation of longer transmission times, the paper proposes another feedback strategy that is based on the theory of compressive sensing, where collision is allowed and all users encode their feedback information and send it back to the base-stations simultaneously. The paper shows that the problem can be formulated as a block sparse recovery problem which is agnostic on the transmission time, which makes it a good alternative to the timer approach when collision is dominant.

  3. Effects of different kinds of robot feedback

    DEFF Research Database (Denmark)

    Fischer, Kerstin; Lohan, K. S.; Nehaniv, C.

    2013-01-01

    In this paper, we investigate to what extent tutors' behavior is influenced by different kinds of robot feedback. In particular, we study the effects of online robot feedback in which the robot responds either contingently to the tutor's social behavior or by tracking the objects presented. Also...

  4. Effective Feedback Procedures in Games for Health.

    Science.gov (United States)

    Baranowski, Moderator Tom; Bower, Participants Kelly; Krebs, Paul; Lamoth, Claudine J; Lyons, Elizabeth J

    2013-12-01

    Feedback on game performance can be provided in many ways (e.g., cumulative points on game achievements, points on selected aspects of game play, biofeedback, brief statements offered during gameplay on choices made, verbal feedback at end of gameplay on overall performance, etc.). Feedback could be used motivationally to maintain player interest and involvement, informationally to guide the player in more effective choices, to build player confidence, and for a variety of other purposes. Although diverse feedback types and purposes are possible, some are more likely to be useful and effective. We have contacted several accomplished game designers and game researchers to obtain their insights into issues in feedback in Games for Health Journal.

  5. Local biogeomorphic feedbacks and macroscale drivers shape coastal wetland distributions

    Science.gov (United States)

    Braswell, A. E.; Heffernan, J. B.

    2016-12-01

    Recent models have demonstrated that lateral biogeomorphic processes are important for the persistence of coastal wetlands in the face of sea level rise and other anthropogenic pressures. Yet empirical studies of marsh ecomorphodynamics have largely focused on vertical accretion. Moreover, local vertical and lateral processes of marsh-building depend on external sediment supply and the wave energy environment, and thus are connected to macroscale characteristics such as estuarine morphology and watershed size. These broad scale drivers, combined with local biogeomorphic feedbacks within wetlands, determine wetland extent. Our goal is to understand the scales at which local biogeomorphic feedbacks and macroscale estuarine and watershed characteristics influence the distribution of coastal marshes. To that end, we examined the distribution of wetland extent and its potential watershed and estuarine drivers at multiple scales along the Atlantic and Gulf coasts, USA. Using existing GIS resources, we delineated extents of coastal wetlands, and generated proxies of sediment input, estuarine energy, and human alteration. We found that distributions of wetland extent were bi-modal at the finest scale of our analysis (approx. 1-100 km2), a finding that is consistent with theoretical models of local marsh feedbacks. At larger spatial scales, distributions of marsh extent were associated with both estuarine size and drainage ratio. These relationships indicate that sediment supply and erosion ultimately constrain the extent of marsh development and persistence, while local feedbacks operate at smaller scales. Our findings support and extend theory and observation at the scale of marsh platforms and lagoons, but also demonstrate the importance of macroscale watershed and estuarine characteristics for wetland establishment and persistence.

  6. Feedback.

    Science.gov (United States)

    Richardson, Barbara K

    2004-12-01

    The emergency department provides a rich environment for diverse patient encounters, rapid clinical decision making, and opportunities to hone procedural skills. Well-prepared faculty can utilize this environment to teach residents and medical students and gain institutional recognition for their incomparable role and teamwork. Giving effective feedback is an essential skill for all teaching faculty. Feedback is ongoing appraisal of performance based on direct observation aimed at changing or sustaining a behavior. Tips from the literature and the author's experience are reviewed to provide formats for feedback, review of objectives, and elements of professionalism and how to deal with poorly performing students. Although the following examples pertain to medical student education, these techniques are applicable to the education of all adult learners, including residents and colleagues. Specific examples of redirection and reflection are offered, and pitfalls are reviewed. Suggestions for streamlining verbal and written feedback and obtaining feedback from others in a fast-paced environment are given. Ideas for further individual and group faculty development are presented.

  7. Monolithic integration of electroabsorption modulators and tunnel injection distributed feedback lasers using quantum well intermixing

    Science.gov (United States)

    Wang, Yang; Pan, Jiao-Qing; Zhao, Ling-Juan; Zhu, Hong-Liang; Wang, Wei

    2010-12-01

    Electroabsorption modulators combining Franz-Keldysh effect and quantum confined Stark effect have been monolithically integrated with tunnel-injection quantum-well distributed feedback lasers using a quantum well intermixing method. Superior characteristics such as extinction ratio and temperature insensitivity have been demonstrated at wide temperature ranges.

  8. Elusive Achievement Effects of Haptic Feedback

    Science.gov (United States)

    Moore, David; Williams, Robert L., II; Luo, Tian; Karadogan, Ernur

    2013-01-01

    Research on haptic feedback has demonstrated limited empirical evidence of its positive learning effects. This research contrasts supportive anecdotal evidence and reports of increased motivation. In an attempt to unify these contrasting results we attempted to identify empirical evidence supporting

  9. The Greenhouse Effect and Climate Feedbacks

    Science.gov (United States)

    Covey, C.; Haberle, R. M.; McKay, C. P.; Titov, D. V.

    This chapter reviews the theory of the greenhouse effect and climate feedback. It also compares the theory with observations, using examples taken from all four known terrestrial worlds with substantial atmospheres: Venus, Earth, Mars, and Titan. The greenhouse effect traps infrared radiation in the atmosphere, thereby increasing surface temperature. It is one of many factors that affect a world's climate. (Others include solar luminosity and the atmospheric scattering and absorption of solar radiation.) A change in these factors — defined as climate forcing — may change the climate in a way that brings other processes — defined as feedbacks — into play. For example, when Earth's atmospheric carbon dioxide increases, warming the surface, the water vapor content of the atmosphere increases. This is a positive feedback on global warming because water vapor is itself a potent greenhouse gas. Many positive and negative feedback processes are significant in determining Earth's climate, and probably the climates of our terrestrial neighbors.

  10. Distributed Feedback Lasers Based on Thiophene/Phenylene Co-Oligomer Single Crystals

    NARCIS (Netherlands)

    Fang, Hong-Hua; Ding, Ran; Lu, Shi-Yang; Yang, Jie; Zhang, Xu-Lin; Yang, Rui; Feng, Jing; Chen, Qi-Dai; Song, Jun-Feng; Sun, Hong-Bo; Fang, Honghua

    2012-01-01

    Organic crystals have great potential for the applications in laser devices. This article presents an effective approach for fabrication of distributed feedback single crystal lasers. With the laser interference ablation method, high quality grating structures have been fabricated on the organic sin

  11. Time-Domain Large Signal Investigation on Dynamic Responses of the GDCC Quarterly Wavelength Shifted Distributed Feedback Semiconductor Laser

    Directory of Open Access Journals (Sweden)

    Hamza Bousseta

    2012-09-01

    Full Text Available A numerical investigation on the dynamic large-signal analysis using a time-domain traveling wave model of quarter wave-shifted distributed feedback semiconductor lasers diode with a Gaussian distribution of the coupling coefficient (GDCC is presented. It is found that the single-mode behavior and the more hole-burning effect corrections of quarter wave-shifted distributed feedback laser with large coupling coefficient can be improved significantly by this new proposed light source.

  12. Feedback Effects of Teaching Quality Assessment: Macro and Micro Evidence

    Science.gov (United States)

    Bianchini, Stefano

    2014-01-01

    This study investigates the feedback effects of teaching quality assessment. Previous literature looked separately at the evolution of individual and aggregate scores to understand whether instructors and university performance depends on its past evaluation. I propose a new quantitative-based methodology, combining statistical distributions and…

  13. FEEDBACK ON A PUBLICLY DISTRIBUTED IMAGE DATABASE: THE MESSIDOR DATABASE

    Directory of Open Access Journals (Sweden)

    Etienne Decencière

    2014-08-01

    Full Text Available The Messidor database, which contains hundreds of eye fundus images, has been publicly distributed since 2008. It was created by the Messidor project in order to evaluate automatic lesion segmentation and diabetic retinopathy grading methods. Designing, producing and maintaining such a database entails significant costs. By publicly sharing it, one hopes to bring a valuable resource to the public research community. However, the real interest and benefit of the research community is not easy to quantify. We analyse here the feedback on the Messidor database, after more than 6 years of diffusion. This analysis should apply to other similar research databases.

  14. Galaxy Evolution: Effects of Stellar Feedback on the Halo Formation

    Science.gov (United States)

    Myers, J. M.; Hartmann, D. H.; The, L.-S.

    2003-05-01

    Recent reviews of Milky Way globular cluster formation indicate three groups associated with the formation of the bulge, disk and halo, and one group associated with accretion processes (van den Bergh 2000). Malinie et al. (1991) showed that the metallicity distribution of the halo globular clusters can be reproduced in the ELS scenario if the initial density profile is nonuniform and kinetic feedback from supernovae is taken into account. Their simulations were performed in 1D and did not include dark matter. In this study, using an N-body/SPH simulation, we attempt to explain the effect of stellar feedback on the formation and distribution of the halo globular clusters. We present 3D simulations of a rotating homogeneous collapse including dark matter, cooling gas, and stars. Three formulations of supernova feedback are considered.

  15. Effects of different kinds of robot feedback

    DEFF Research Database (Denmark)

    Fischer, Kerstin; Lohan, K. S.; Nehaniv, C.

    2013-01-01

    -driven condition, in which the robot tracked the objects presented, tutors do not change their behavior significantly, even though in both conditions the robot develops from a prelinguistic stage to producing keywords. Socially contingent robot feedback has thus the potential to influence tutors' behavior over......In this paper, we investigate to what extent tutors' behavior is influenced by different kinds of robot feedback. In particular, we study the effects of online robot feedback in which the robot responds either contingently to the tutor's social behavior or by tracking the objects presented. Also......, we investigate the impact of the robot's learning success on tutors' tutoring strategies. Our results show that only in the condition in which the robot's behavior is socially contingent, the human tutors adjust their behavior to the robot. In the developmentally equally plausible object...

  16. Relative Effects of Daily Feedback and Weekly Feedback on Customer Service Behavior at a Gas Station

    Science.gov (United States)

    So, Yongjoon; Lee, Kyehoon; Oah, Shezeen

    2013-01-01

    The relative effects of daily and weekly feedback on customer service behavior at a gas station were assessed using an ABC within-subjects design. Four critical service behaviors were identified and measured daily. After baseline (A), weekly feedback (B) was introduced, and daily feedback (C) was introduced in the next phase. The results indicated…

  17. Feedback Perceptions and Attribution by Secretarial Employees: Effects of Feedback-Content and Sender Characteristics

    Science.gov (United States)

    Raemdonck, Isabel; Strijbos, Jan-Willem

    2013-01-01

    Purpose: Theoretical explanations for the diverse reactive feedback from secretarial employees in different career phases are relatively unexplored. However, research examining age differences in the impact of feedback suggests that the effects of performance feedback may differ for employees in the early career phase and employees in the late…

  18. Wafer-scale fabrication of polymer distributed feedback lasers

    DEFF Research Database (Denmark)

    Christiansen, Mads Brøkner; Schøler, Mikkel; Balslev, Søren

    2006-01-01

    The authors demonstrate wafer-scale, parallel process fabrication of distributed feedback (DFB) polymer dye lasers by two different nanoimprint techniques: By thermal nanoimprint lithography (TNIL) in polymethyl methacrylate and by combined nanoimprint and photolithography (CNP) in SU-8. In both...... techniques, a thin film of polymer, doped with rhodamine-6G laser dye, is spin coated onto a Borofloat glass buffer substrate and shaped into a planar waveguide slab with first order DFB surface corrugations forming the laser resonator. When optically pumped at 532 nm, lasing is obtained in the wavelength...... range between 576 and 607 nm, determined by the grating period. The results, where 13 laser devices are defined across a 10 cm diameter wafer substrate, demonstrate the feasibility of NIL and CNP for parallel wafer-scale fabrication of advanced nanostructured active optical polymer components...

  19. Effective Instructor Feedback: Perceptions of Online Graduate Students

    Directory of Open Access Journals (Sweden)

    Beverley Getzlaf

    2009-07-01

    Full Text Available This descriptive study explored online graduate students' perceptions of effective instructor feedback. The objectives of the study were to determine the students’ perceptions of the content of effective instructor feedback (“what should be included in effective feedback?” and the process of effective instructor feedback (“how should effective feedback be provided?”. The participants were students completing health-related graduate courses offered exclusively online. Data were collected via a survey that included open ended questions inviting participants to share their perspectives regarding effective online instructor feedback. Thematic analysis revealed five major themes: student involvement/individualization, gentle guidance, being positively constructive, timeliness and future orientation. We conclude that effective instructor feedback has positive outcomes for the students. Future studies are warranted to investigate strategies to make feedback a mutual process between instructor and student that supports an effective feedback cycle.

  20. Effects of Web-Based Feedback on Students' Learning

    Science.gov (United States)

    van Kol, Simone; Rietz, Christian

    2016-01-01

    Feedback plays an important role in supporting students' learning process. Nonetheless, providing feedback is still rather unusual in higher education. Moreover, research on the design of ideal feedback as well as its effects is rare. In order to contribute to the development of this field, a web-based feedback system was implemented in a lecture…

  1. Facilitating EFL Learners' Oral Communication through Effective Feedback

    Institute of Scientific and Technical Information of China (English)

    李俊芬

    2002-01-01

    Feedback is an indispensable component of teaching process.Research finding shows that one of the keys to successful language learning lies in the feedback learner receives from others.This paper proposed some solutions to feedback problems in oral communication of non-English majors.The author finds that feedback can work effectively only when learners willingly internalize teacher feedback after their affective filter.

  2. Output Feedback Distributed Containment Control for High-Order Nonlinear Multiagent Systems.

    Science.gov (United States)

    Li, Yafeng; Hua, Changchun; Wu, Shuangshuang; Guan, Xinping

    2017-01-31

    In this paper, we study the problem of output feedback distributed containment control for a class of high-order nonlinear multiagent systems under a fixed undirected graph and a fixed directed graph, respectively. Only the output signals of the systems can be measured. The novel reduced order dynamic gain observer is constructed to estimate the unmeasured state variables of the system with the less conservative condition on nonlinear terms than traditional Lipschitz one. Via the backstepping method, output feedback distributed nonlinear controllers for the followers are designed. By means of the novel first virtual controllers, we separate the estimated state variables of different agents from each other. Consequently, the designed controllers show independence on the estimated state variables of neighbors except outputs information, and the dynamics of each agent can be greatly different, which make the design method have a wider class of applications. Finally, a numerical simulation is presented to illustrate the effectiveness of the proposed method.

  3. Effects of AGN feedback on LCDM galaxies

    CERN Document Server

    Lagos, Claudia del P; Padilla, Nelson D

    2008-01-01

    We study the effects of Active Galactic Nuclei (AGN) feedback on the formation and evolution of galaxies in a semi-analytic model of galaxy formation. This model is an improved version of the one described by Cora (2006), which now considers the growth of black holes (BHs) as driven by (i) gas accretion during merger-driven starbursts and mergers with other BHs, (ii) accretion during starbursts triggered by disc instabilities, and (iii) accretion of gas cooled from quasi-hydrostatic hot gas haloes. It is assumed that feedback from AGN operates in the later case. The model has been calibrated in order to reproduce observational correlations between BH mass and mass, velocity dispersion, and absolute magnitudes of the galaxy bulge. AGN feedback has a strong impact on reducing or even suppressing gas cooling, an effect that becomes important at lower redshifts. This phenomenon helps to reproduce the observed galaxy luminosity function (LF) in the optical and near IR bands at z=0, and the cosmic star formation ra...

  4. Feedback providing improvement strategies and reflection on feedback use: Effects on students' writing motivation, process, and performance

    NARCIS (Netherlands)

    H. Duijnhouwer; F.J. Prins; K.M. Stokking

    2012-01-01

    This study investigated the effects of feedback providing improvement strategies and a reflection assignment on students’ writing motivation, process, and performance. Students in the experimental feedback condition (n = 41) received feedback including improvement strategies, whereas students in the

  5. Effects of Informative and Confirmatory Feedback on Brain Activation During Negative Feedback Processing

    Directory of Open Access Journals (Sweden)

    Yeon-Kyoung eWoo

    2015-06-01

    Full Text Available The current study compared the effects of informative and confirmatory feedback on brain activation during negative feedback processing. For confirmatory feedback trials, participants were informed that they had failed the task, whereas informative feedback trials presented task relevant information along with the notification of their failure. Fourteen male undergraduates performed a series of spatial-perceptual tasks and received feedback while their brain activity was recorded. During confirmatory feedback trials, greater activations in the amygdala, dorsal anterior cingulate cortex, and the thalamus (including the habenular were observed in response to incorrect responses. These results suggest that confirmatory feedback induces negative emotional reactions to failure. In contrast, informative feedback trials elicited greater activity in the dorsolateral prefrontal cortex (DLPFC when participants experienced failure. Further psychophysiological interaction (PPI analysis revealed a negative coupling between the DLPFC and the amygdala during informative feedback relative to confirmatory feedback trials. These findings suggest that providing task-relevant information could facilitate implicit down-regulation of negative emotions following failure.

  6. VUV free electron laser with a distributed feedback cavity

    Energy Technology Data Exchange (ETDEWEB)

    Chen, J.; Fujita, M.; Asakawa, M. [Osaka Univ. (Japan)] [and others

    1995-12-31

    Development of FEL to the VUV/x-ray regime is looked as one of the possible directions to its success. For eliminating the need for optical cavities, difficult to be built at that regime, we propose a VUV (50nm) SASE FEL. According to Pellegrini`s scaling law, for a 290MeV/200A e-beam passing through a 10.8m long and 2cm period wiggler, a high peak power 85.5MW and a high average brightness 2.44 X 10{sup +21} (photons/[mm{sup 2}.mrad{sup 2}.bw]) can be obtained. However, it requires {epsilon} n=2.3mm.mrad and {Delta}{gamma}/{gamma} = 0.15% about one order above the practical parameters we can realize. For enhancing the efficiency and decreasing the requirements on the e-beam quality and the wiggler length, we put forward a concept of VUV FEL with a distributed feedback cavity. In x-ray region, the natural periodicity of crystals provides strong Bragg coupling and it has been demonstrated as the parametric radiation. In vuv region, current intense research on superlattice can provide a periodical structure with a short period in 250 {Angstrom} order. High-performance vuv multilayer coatings on the inner-wall of the waveguide are used to guide the spontaneous emission and decrease the x-ray ohmic losses on the roundtrip passes. By this DFB cavity structure, it is expected to realize the lasing in a smaller size. Other practical methods such as the optical klystron for shortening the wiggler length and the tapper wiggler for enhancing the saturation power are also considered. The analytical considerations are based on the 1-D FEL equations and 1-D perturbation theory of dielectric waveguide.

  7. VUV free electron laser with a distributed feedback cavity

    Energy Technology Data Exchange (ETDEWEB)

    Chen, J.; Fujita, M.; Asakawa, M. [Osaka Univ. (Japan)] [and others

    1995-12-31

    Development of FEL to the VUV/x-ray regime is looked as one of the possible directions to its success. For eliminating the need for optical cavities, difficult to be built at that regime, we propose a VUV (50nm) SASE FEL. According to Pellegrini`s scaling law, for a 290MeV/200A e-beam passing through a 10.8m long and 2cm period wiggler, a high peak power 85.5MW and a high average brightness 2.44 X 10{sup +21} (photons/[mm{sup 2}.mrad{sup 2}.bw]) can be obtained. However, it requires {epsilon} n=2.3mm.mrad and {Delta}{gamma}/{gamma} = 0.15% about one order above the practical parameters we can realize. For enhancing the efficiency and decreasing the requirements on the e-beam quality and the wiggler length, we put forward a concept of VUV FEL with a distributed feedback cavity. In x-ray region, the natural periodicity of crystals provides strong Bragg coupling and it has been demonstrated as the parametric radiation. In vuv region, current intense research on superlattice can provide a periodical structure with a short period in 250 {Angstrom} order. High-performance vuv multilayer coatings on the inner-wall of the waveguide are used to guide the spontaneous emission and decrease the x-ray ohmic losses on the roundtrip passes. By this DFB cavity structure, it is expected to realize the lasing in a smaller size. Other practical methods such as the optical klystron for shortening the wiggler length and the tapper wiggler for enhancing the saturation power are also considered. The analytical considerations are based on the 1-D FEL equations and 1-D perturbation theory of dielectric waveguide.

  8. Altered Sensory Feedbacks in Pianist's Dystonia: the altered auditory feedback paradigm and the glove effect

    Directory of Open Access Journals (Sweden)

    Felicia Pei-Hsin Cheng

    2013-12-01

    Full Text Available Background: This study investigates the effect of altered auditory feedback (AAF in musician's dystonia (MD and discusses whether altered auditory feedback can be considered as a sensory trick in MD. Furthermore, the effect of AAF is compared with altered tactile feedback, which can serve as a sensory trick in several other forms of focal dystonia. Methods: The method is based on scale analysis (Jabusch et al. 2004. Experiment 1 employs synchronization paradigm: 12 MD patients and 25 healthy pianists had to repeatedly play C-major scales in synchrony with a metronome on a MIDI-piano with 3 auditory feedback conditions: 1. normal feedback; 2. no feedback; 3. constant delayed feedback. Experiment 2 employs synchronization-continuation paradigm: 12 MD patients and 12 healthy pianists had to repeatedly play C-major scales in two phases: first in synchrony with a metronome, secondly continue the established tempo without the metronome. There are 4 experimental conditions, among them 3 are the same altered auditory feedback as in Experiment 1 and 1 is related to altered tactile sensory input. The coefficient of variation of inter-onset intervals of the key depressions was calculated to evaluate fine motor control. Results: In both experiments, the healthy controls and the patients behaved very similarly. There is no difference in the regularity of playing between the two groups under any condition, and neither did AAF nor did altered tactile feedback have a beneficial effect on patients’ fine motor control. Conclusions: The results of the two experiments suggest that in the context of our experimental designs, AAF and altered tactile feedback play a minor role in motor coordination in patients with musicians' dystonia. We propose that altered auditory and tactile feedback do not serve as effective sensory tricks and may not temporarily reduce the symptoms of patients suffering from MD in this experimental context.

  9. Feedback effect on flute dynamics in a mirror machine

    Science.gov (United States)

    Be'Ery, Ilan; Seemann, Omri

    2015-11-01

    Active feedback techniques may stabilize the flute instability in mirror traps and make them viable candidates for fusion machines. A fast feedback with optical sensors and electrical actuators was implemented in a table-top mirror machine and used to study several aspects of feedback stabilization. For a cold, dense plasma the feedback reduces dramatically the flute amplitude of the first two mode. For higher temperature plasma, a significant increase of plasma density due to feedback stabilization is also demonstrated. The effect of changing feedback gain and phase has some interesting feature such as asymmetry with respect to positive and negative phase shifts and non-monotonic dependence of flute amplitude on feedback gain. These effects are explained using simplified analytic model of the flute and feedback.

  10. The Effects of Feedback as Interpersonal Reciprocities

    Science.gov (United States)

    Levenstein, Joseph; And Others

    1977-01-01

    Tests the hypothesis that a response to a given feedback statement will be its reciprocal. In Phase 1, a pool of feedback statements was written and scaled along dimensions of power (dominance-submission) and affect (affection-hostility). In Phase 2, these statements were used as the basis for giving feedback and replying to it. (Author)

  11. Novel UEP LT Coding Scheme with Feedback Based on Different Degree Distributions

    Directory of Open Access Journals (Sweden)

    Li Ya-Fang

    2016-01-01

    Full Text Available Traditional unequal error protection (UEP schemes have some limitations and problems, such as the poor UEP performance of high priority data and the seriously sacrifice of low priority data in decoding property. Based on the reasonable applications of different degree distributions in LT codes, this paper puts forward a novel UEP LT coding scheme with a simple feedback to compile these data packets separately. Simulation results show that the proposed scheme can effectively protect high priority data, and improve the transmission efficiency of low priority data from 2.9% to 22.3%. Furthermore, it is fairly suitable to apply this novel scheme to multicast and broadcast environments since only a simple feedback introduced.

  12. Effects of Differential Feedback on Students' Examination Performance

    Science.gov (United States)

    Lipnevich, Anastasiya A.; Smith, Jeffrey K.

    2009-01-01

    The effects of feedback on performance and factors associated with it were examined in a large introductory psychology course. The experiment involved college students (N = 464) working on an essay examination under 3 conditions: no feedback, detailed feedback that was perceived by participants to be provided by the course instructor, and detailed…

  13. The Effects of Online Feedback Training on Students' Text Revision

    Science.gov (United States)

    Yang, Yu-Fen; Meng, Wen-Ting

    2013-01-01

    Oftentimes, college students who learn English as a Foreign Language (EFL) provide their peers with incorrect and misleading feedback during text revision. To improve the effectiveness of peer feedback, this study examined the degree to which online feedback training impacted EFL college students' text revisions. A sample of 50 college students…

  14. Research on Method of Multisensor Distributed Track Fusion Based on Feedback Integration

    Institute of Scientific and Technical Information of China (English)

    YANGGuosheng; WENChenglin; TANMin

    2003-01-01

    Multisensor distributed track fusion based on feedback integration is studied in this paper. Firstly,the tracking algorithms of each sensor in local (processor)and the track fusion algorithm on the basis of global in-formation in center (processor) are given after the general structure of multisensor distributed track fusion based on feedback integration is put forward. Secondly, one step tar-get state predictions along with covariance matrixes are fed back to the interrelated sensors to form new tracking gates for the corresponding targets, and then the intersection of the new tracking gate and the original gate formed before feedback for a certain target is taken as the effective track-ing gate for the next estimation, to decrease the computing load of PDA (probability data association). In addition,target instantiation is given to the sensor that has not ob-tained the target track, while other sensors have obtained.At last, take IR and radar as an example, simulation re-searches are performed both on the original algorithm and the one presented by this paper.

  15. Negative feedback effects on star formation history and cosmic reionization

    CERN Document Server

    Wang, Lei; Xiang, Shouping; Yuan, Ye-Fei

    2008-01-01

    After considering the effects of negative feedback on the process of star formation, we explore the relationship between star formation process and the associated feedback, by investigating how the mechanical feedback from supernovae(SNe) and radiative feedback from luminous objects regulate the star formation rate and therefore affect the cosmic reionization.Based on our present knowledge of the negative feedback theory and some numerical simulations, we construct an analytic model in the framework of the Lambda cold dark matter model. In certain parameter regions, our model can explain some observational results properly. In large halos(T_vir>10000 K), both mechanical and radiative feedback have a similar behavior: the relative strength of negative feedback reduces as the redshift decreases. In contrast, in small halos (T_vir<10000 K$) that are thought to breed the first stars at early time, the radiative feedback gets stronger when the redshift decreases. And the star formation rate in these small halos...

  16. Effects of Mechanical and Radiative Supernova Feedback on Subhalo Evolution

    Science.gov (United States)

    Quirk, Amanda; Choi, Ena; Ostriker, Jeremiah P.

    2017-01-01

    Using cosmological hydrodynamical simulations, we investigate the effects supernova feedback has on populations of subhalos at current redshift. A group of halos was run through two simulations, each with different feedback models. One had thermal feedback, and the other had mechanical and radiative feedback. We used a friend-of-friend halo finder on the output of these simulations to explore the stellar and dark matter subhalos created. The number of stellar subhalos created by the mechanical feedback simulation was significantly less than the number created by the thermal feedback model, especially at low mass. Thus, the mechanical feedback model created a number of stellar subhalos more consistent with observations. The mechanical feedback model also showed a presence of dark matter subhalos that lacked stellar particles, or dark subhalos. The results of this analysis can give insight to the Missing Satellite Problem.

  17. Permanence of a Single Species System with Distributed Time Delay and Feedback Control

    Directory of Open Access Journals (Sweden)

    Yali Shen

    2012-01-01

    Full Text Available We study the permanence of a classofsingle species system with distributed time delay and feedback controls. General criteria on permanence are established in this paper. A very important fact is found in our results; that is, the feedback control is harmless to the permanence of species.

  18. The Effect of Combination of Video Feedback and Audience Feedback on Social Anxiety: Preliminary Findings.

    Science.gov (United States)

    Chen, Junwen; Mak, Rebecca; Fujita, Satoko

    2015-09-01

    Although video feedback (VF) is shown to improve appraisals of social performance in socially anxious individuals, its impact on state anxiety during a social situation is mixed. The current study investigated the effect of combined video feedback and audience feedback (AF) on self-perceptions of performance and bodily sensations as well as state anxiety pertaining to a speech task. Forty-one socially anxious students were randomly allocated to combined video feedback with audience feedback (VF + AF), video feedback only (VF), audience feedback only (AF), or a control condition. Following a 3-min speech, participants in the VF + AF, VF, and AF conditions watched the videotape of their speech with cognitive preparation in the presence of three confederates who served as audience, and/or received feedback from the confederates, while the control group watched their videotaped speech without cognitive preparation. Both VF + AF and AF conditions improved distorted appraisal of performance and bodily sensations as well as state anxiety. The clinical implications of these findings are discussed.

  19. The Effectiveness of Positive Feedback in Teaching Speaking Skill

    Directory of Open Access Journals (Sweden)

    Arief Muhsin

    2016-05-01

    Full Text Available The research was aimed at finding out the students’ responses and perceptions toward the corrective feedback given in teaching speaking activity. The research applied quantitative methods by sending questionnaires to 70 students. The students’ responses and perceptions for teacher’s corrective feedback indicated that students think their spoken error should be corrected. In addition, the students want their teacher focus more on. They also agree if their friends should correct their error. The most popular corrective feedbacks in teaching speaking are the explicit correction, elicitation, and repetition. They have an effective function in detecting the students’ mispronunciation and low accuracy and fluency. The other corrective feedback like implicit correction, recast, clarification request, and metalinguistic feedback are not favored because the percentage is lower than other corrective feedback. It indicates that not all of corrective feedback is effectively used in speaking.

  20. The effect of radiative feedback on disc fragmentation

    CERN Document Server

    Mercer, Anthony

    2016-01-01

    Protostellar discs may become massive enough to fragment producing secondary low-mass objects: planets, brown dwarfs and low-mass stars. We study the effect of radiative feedback from such newly-formed secondary objects using radiative hydrodynamic simulations. We compare the results of simulations without any radiative feedback from secondary objects with those where two types of radiative feedback are considered: (i) continuous, and (ii) episodic. We find that: (i) continuous radiative feedback stabilizes the disc and suppresses further fragmentation, reducing the number secondary objects formed; (ii) episodic feedback from secondary objects heats and stabilises the disc when the outburst occurs, but shortly after the outburst stops, the disc becomes unstable and fragments again. However, fewer secondary objects are formed compared to the the case without radiative feedback. We also find that the mass growth of secondary objects is mildly suppressed due to the effect of their radiative feedback. However, th...

  1. Effects of digital vibrotactile speech feedback on overt stuttering frequency.

    Science.gov (United States)

    Snyder, Gregory J; Blanchet, Paul; Waddell, Dwight; Ivy, Lennette J

    2009-02-01

    Fluency-enhancing speech feedback, originating from internally or externally generated sources via auditory or visual sensory modalities is not restricted to a specific sensory modality or signal origination. Research suggests that externally generated digital vibrotactile speech feedback serves as an effective fluency enhancer. The present purpose was to test the fluency-enhancing effects of self-generated digital vibrotactile speech feedback on stuttering frequency. Adults who stutter read passages aloud over the telephone, both with and without digital vibrotactile speech feedback. Digital vibrotactile speech feedback was operationally defined as feeling the vibrations of the thyroid cartilage with the thumb and index finger while speaking. Analysis indicated that self-generated digital vibrotactile speech feedback reduced overt stuttering frequency by an average of 72%. As the specific neural mechanisms associated with stuttering and fluency enhancement from tactile speech feedback remain unknown, theoretical implications and clinical applications were discussed.

  2. Feedback Providing Improvement Strategies and Reflection on Feedback Use: Effects on Students' Writing Motivation, Process, and Performance

    Science.gov (United States)

    Duijnhouwer, Hendrien; Prins, Frans J.; Stokking, Karel M.

    2012-01-01

    This study investigated the effects of feedback providing improvement strategies and a reflection assignment on students' writing motivation, process, and performance. Students in the experimental feedback condition (n = 41) received feedback including improvement strategies, whereas students in the control feedback condition (n = 41) received…

  3. A Novel Multisection Distributed Feedback Laser with Varied Ridge Width for Self-Pulsation Generation

    Institute of Scientific and Technical Information of China (English)

    WAN Qin; SUN Chang-Zheng; XIONG Bing; WANG Jian; LUO Yi

    2006-01-01

    @@ A novel ridge-waveguide multisection (MS) distributed feedback (DFB) laser, which consists of two identical DFB sections but different ridge widths, is proposed to generate beating-type self-pulsations (SPs).

  4. Tunable Erbium-Doped Fiber Laser Based on Random Distributed Feedback

    National Research Council Canada - National Science Library

    Lulu Wang; Xinyong Dong; Shum, Perry Ping; Haibin Su

    2014-01-01

    A tunable erbium-doped fiber (EDF) laser based on random distributed feedback through backward Rayleigh scattering in a 20-km-long single-mode fiber and a tunable fiber Fabry-Perot interferometer filter is demonstrated...

  5. Distributed feedback laser amplifiers combining the functions of amplifiers and channel filters

    DEFF Research Database (Denmark)

    Wang, Z.; Durhuus, T.; Mikkelsen, Benny;

    1994-01-01

    A dynamic model for distributed feedback amplifiers, including the mode coupled equations and the carrier rate equation, is established. The presented mode coupled equations have taken into account the interaction between fast changing optical signal and the waveguide with corrugations. By showin...... the possibility of amplifying 100 ps pulses without pulse broadening, we anticipate that a distributed feedback amplifier can be used as a combined amplifier and channel filter in high bit rate transmission systems....

  6. EFFECTS OF THREE FEEDBACK CONDITIONS ON AEROBIC SWIM SPEEDS

    Directory of Open Access Journals (Sweden)

    Pedro Pérez Soriano

    2009-03-01

    Full Text Available The purpose of this study was twofold: (a to develop an underwater chronometer capable to provide feedback while the athlete is swimming, as well as being a control tool for the coach, and (b to analyse its feedback effect on swim pace control compared with feedback provided by the coach and with no feedback, in 25 m and 50 m swimming pools. 30 male swimmers of national level volunteer to participate. Each swimmer swam 3 x 200 m at aerobic speed (AS and 3 x 200 m just under the anaerobic threshold speed (AnS, each swam repetition with a different feedback condition: chronometer, coach and without feedback. Results (a validate the chronometer system developed and (b show that swimmers pace control is affected by the type of feedback provided, the swim speed elected and the size of the swimming pool

  7. Providing Effective Feedback to EFL Student Teachers

    Science.gov (United States)

    Ali, Holi Ibrahim Holi; Al-Adawi, Hamed Ahmed

    2013-01-01

    Feedback on school practicum is of utmost importance for student teachers to help them to develop their pedagogical and teaching skills. This paper attempts to collect data from both student teachers and their mentors in an ELT teacher training programme in Oman to answer the questions which are raised by this study: 1) What kind of feedback do…

  8. The Effect of Information Feedback in Construction Bidding

    Directory of Open Access Journals (Sweden)

    Alexander Soo

    2010-07-01

    Full Text Available  With the goal to achieve efficiency in bidding competitions, many codes of bidding procedure recommend clients provide contractors with bidding feedback information. Contractors strive to bid competitively via learning based on their experiences in past bidding attempts. The level of bidding feedback information, however, varies across clients. In many cases, clients do not provide feedback or provide insufficient feedback to contractors. Focussing on two information feedback conditions (full and partial, we examine: (i the changes in bidding trend over time, and (ii the effects of bidding feedback information on bidders’ competitiveness in bidding. Data were gathered using a bidding experiment that involved student (inexperienced bidders with a construction project management background. The results show that the variations in bids over time for full information feedback condition are statistically significant, but not for bids from bidders with partial bidding feedback information. Bidders with full bidding feedback information are more competitive than those with partial bidding feedback information. The findings add to both our theoretical and empirical understanding of construction bidding: an understanding of the process of changes in the price of building work, and how the process can be manipulated through the release of bidding feedback information.

  9. Effects of unwanted feedback on synchronized chaotic optical communications.

    Science.gov (United States)

    Li, Xiaofeng; Pan, Wei; Luo, Bin; Ma, Dong

    2006-04-10

    The effects of unwanted external optical feedback on synchronized chaotic optical communication systems are studied numerically. We consider an open-loop configuration consisting of a transmitter laser with double external optical feedbacks and a receiver laser with optical injection from the transmitter laser. First, including the effects of unwanted optical feedback, the synchronization performances of both the complete synchronization and the generalized synchronization are examined. Then the encoding and decoding performances of the generalized synchronization and the effects of the introduced feedback are investigated, respectively. Finally, we study the control of the unwanted feedback on the dynamics of the transmitter laser and briefly discuss the system security when the transmitter laser is driven to operate in a steady state or periodic oscillation state by the additional feedback.

  10. Distributed Cooperative Secondary Control of Microgrids Using Feedback Linearization

    DEFF Research Database (Denmark)

    Bidram, Ali; Davoudi, Ali; Lewis, Frank;

    2013-01-01

    This paper proposes a secondary voltage control of microgrids based on the distributed cooperative control of multi-agent systems. The proposed secondary control is fully distributed; each distributed generator (DG) only requires its own information and the information of some neighbors...

  11. Evaluation of multimodal feedback effects on improving rowing competencies

    Directory of Open Access Journals (Sweden)

    Korman Maria

    2011-12-01

    Full Text Available This study focused on the selection and preliminary evaluation of different types of modal and information feedback in virtual environment to facilitate acquisition and transfer of a complex motor-cognitive skill of rowing. Specifically, we addressed the effectiveness of immediate information feedback provided visually as compared to sensory haptic feedback on the improvement in hands kinematics and changes in cognitive load during the course of learning the basic rowing technique. Several pilot experiments described in this report lead to the evaluation and optimization of the training protocol, to enhance facilitatory effects of adding visual and haptic feedback during training.

  12. Effects of Performance Feedback on Typing Speed and Accuracy

    Science.gov (United States)

    Tittelbach, Danielle; Fields, Lanny; Alvero, Alicia M.

    2008-01-01

    Performance feedback is one of the most widely used tools in organizational settings. To date, little research has been conducted focusing on comparisons of the differential effects of the sources, frequency, or media used for feedback on both the quality and quantity of performance. This research investigated the effects of different feedback…

  13. Effect of External Optical Feedback for Nano-laser Structures

    DEFF Research Database (Denmark)

    Taghizadeh, Alireza; Mørk, Jesper; Chung, Il-Sug

    2013-01-01

    We theoretically investigated the effect of optical feedback on a photonic crystal nanolaser, comparing with conventional in-plane and vertical-cavity lasers.......We theoretically investigated the effect of optical feedback on a photonic crystal nanolaser, comparing with conventional in-plane and vertical-cavity lasers....

  14. The Effectiveness of Corrective Feedback in EFL Learning in China

    Institute of Scientific and Technical Information of China (English)

    孙瑜

    2015-01-01

    It is known that corrective feedback is effective in developing English learners’ interlanguage.Therefore,it is meaningful to discuss the effectiveness of corrective feedback in the context of EFL in China and to find instructive ways in the classroom implication.

  15. Effects of Intrinsic Motivation on Feedback Processing During Learning

    OpenAIRE

    DePasque, Samantha; Tricomi, Elizabeth

    2015-01-01

    Learning commonly requires feedback about the consequences of one’s actions, which can drive learners to modify their behavior. Motivation may determine how sensitive an individual might be to such feedback, particularly in educational contexts where some students value academic achievement more than others. Thus, motivation for a task might influence the value placed on performance feedback and how effectively it is used to improve learning. To investigate the interplay between intrinsic mot...

  16. Ten tips for receiving feedback effectively in clinical practice.

    Science.gov (United States)

    Algiraigri, Ali H

    2014-01-01

    Despite being recognized as a fundamental part of the educational process and emphasized for several decades in medical education, the influence of the feedback process is still suboptimal. This may not be surprising, because the focus is primarily centered on only one half of the process - the teachers. The learners are the targets of the feedback process and improvement needs to be shifted. Learners need to be empowered with the skills needed to receive and utilize feedback and compensate for less than ideal feedback delivery due to the busy clinical environment. Based on the available feedback literature and clinical experience regarding feedback, the author developed 10 tips to empower learners with the necessary skills to seek, receive, and handle feedback effectively, regardless of how it is delivered. Although, most of the tips are directed at the individual clinical trainee, this model can be utilized by clinical educators involved in learner development and serve as a framework for educational workshops or curriculum. Ten practical tips are identified that specifically address the learner's role in the feedback process. These tips not only help the learner to ask, receive, and handle the feedback, but will also ease the process for the teachers. Collectively, these tips help to overcome most, if not all, of the barriers to feedback and bridge the gaps in busy clinical practices. Feedback is a crucial element in the educational process and it is shown that we are still behind in the optimal use of it; thus, learners need to be taught how to better receive and utilize feedback. The focus in medical education needs to balance the two sides of the feedback process. It is time now to invest on the learner's development of skills that can be utilized in a busy day-to-day clinical practice.

  17. The Effect of Giving Feedback to Students' Writing

    Directory of Open Access Journals (Sweden)

    Mochamad Zainuddin

    2004-01-01

    Full Text Available Although writing is as important as other skills such as listening, speaking, and reading, it needs more special attention. In order to write well, students need a long process to learn to write and they need continous feedback. The aim of this article is to know whether giving feedback to students' writing has a significant effect or not. Two groups of students, experimental and control, were involved. The compositions of the first group were given feedback, while those of the second group were not given feedback. The study shows that provision of feedback improves student's writing. In light of the result of the study, it is recommended that teachers provide feedback on students' writing.

  18. High-power random distributed feedback fiber laser: From science to application

    Energy Technology Data Exchange (ETDEWEB)

    Du, Xueyuan [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Naval Academy of Armament, Beijing 100161 (China); Zhang, Hanwei; Xiao, Hu; Ma, Pengfei; Wang, Xiaolin; Zhou, Pu; Liu, Zejin [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2016-10-15

    A fiber laser based on random distributed feedback has attracted increasing attention in recent years, as it has become an important photonic device and has found wide applications in fiber communications or sensing. In this article, recent advances in high-power random distributed feedback fiber laser are reviewed, including the theoretical analyses, experimental approaches, discussion on the practical applications and outlook. It is found that a random distributed feedback fiber laser can not only act as an information photonics device, but also has the feasibility for high-efficiency/high-power generation, which makes it competitive with conventional high-power laser sources. In addition, high-power random distributed feedback fiber laser has been successfully applied for midinfrared lasing, frequency doubling to the visible and high-quality imaging. It is believed that the high-power random distributed feedback fiber laser could become a promising light source with simple and economic configurations. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Feedback effects on students' writing motivation, process, and performance

    NARCIS (Netherlands)

    Duijnhouwer, H.

    2010-01-01

    Many students’ writing capacities remain insufficient during college years (Kellogg & Whiteford, 2009). Teachers try to improve students’ writing skills by providing them with feedback on their texts. Remarkably, research on the effects of feedback provided on written products is scarce (Graham &

  20. Feedback effects on students' writing motivation, process, and performance

    NARCIS (Netherlands)

    Duijnhouwer, H.

    2010-01-01

    Many students’ writing capacities remain insufficient during college years (Kellogg & Whiteford, 2009). Teachers try to improve students’ writing skills by providing them with feedback on their texts. Remarkably, research on the effects of feedback provided on written products is scarce (Graham & Pe

  1. Probing Feedback with the Thermal Sunyaev-Zel'dovich Effect

    Science.gov (United States)

    Crichton, Devin T.; Atacama Cosmology Telescope Collaboration

    2017-01-01

    The thermal Sunyaev-Zel'dovich (tSZ) effect imparts a spectral distortion to the Cosmic Microwave Background (CMB) at millimeter wavelengths, the amplitude of which provides a redshift independent probe of the thermal energy of diffuse ionized gas. With the goal of constraining the impact of feedback from active galactic nuclei on the diffuse circumgalactic environment, we have analyzed the tSZ contribution to the stacked spectral energy distributions of both radio galaxies and optically selected quasars, using millimeter and far-infrared surveys from the Atacama Cosmology Telescope and the Herschel Space Observatory. I will present the results of these studies and discuss the evidence we find for the tSZ effect associated with both these samples. While the tSZ signal from radio galaxies is consistent with expectations from purely gravitational heating, the tSZ amplitude associated with the quasar sample is found to be indicative of an additional heating source for the expected range of quasar host halo masses. We attribute this excess thermal energy to feedback influencing the circumgalactic environments of these systems. I will discuss the consequences of these results and additionally provide forecasts for tSZ measurements from future samples and surveys.

  2. Active Probing Feedback based Self Configurable Intelligent Distributed Antenna System

    DEFF Research Database (Denmark)

    Kumar, Ambuj

    challenge through a viable solution that is based on injecting intelligence and services in parallel layers through a Distributed Antenna Systems (DAS) network. This approach would enable the remote sites to acquire intelligence and a resource pool at the same time, thereby managing the network dynamics...... as Self Configurable Distributed Antenna System (SCIDAS)....... collectively as Place Time Coverage & Capacity (PTC2). The dissertation proves through the concept of the PTC2 that the network performance can severely be degraded by the excessive and unrealistic site demands, the network management inefficiency, and the consequence of the accumulation of subscribers...

  3. Effects of Supernova Feedback on the Formation of Galaxies

    CERN Document Server

    Scannapieco, Cecilia; White, Simon D M; Springel, Volker

    2008-01-01

    We study the effects of Supernova (SN) feedback on the formation of galaxies using hydrodynamical simulations in a Lambda-CDM cosmology. We use an extended version of the code GADGET-2 which includes chemical enrichment and energy feedback by Type II and Type Ia SN, metal-dependent cooling and a multiphase model for the gas component. We focus on the effects of SN feedback on the star formation process, galaxy morphology, evolution of the specific angular momentum and chemical properties. We find that SN feedback plays a fundamental role in galaxy evolution, producing a self-regulated cycle for star formation, preventing the early consumption of gas and allowing disks to form at late times. The SN feedback model is able to reproduce the expected dependence on virial mass, with less massive systems being more strongly affected.

  4. Modeling 3D soil and sediment distributions for assessing catchment structure and hydrological feedbacks

    Science.gov (United States)

    Maurer, Thomas; Brück, Yasemine; Hinz, Christoph; Gerke, Horst H.

    2015-04-01

    . The established initial sediment distributions provide a basis for the consecutive modelling of feedbacks between surface and subsurface water flow and changes in soil properties, e.g. by using a landscape evolution model. The results should allow conclusions about the effect of different initial structural setups on the further dynamic landscape development at catchment scale.

  5. The effect of radiative feedback on disc fragmentation

    Science.gov (United States)

    Mercer, Anthony; Stamatellos, Dimitris

    2017-02-01

    Protostellar discs may become massive enough to fragment producing secondary low-mass objects: planets, brown dwarfs and low-mass stars. We study the effect of radiative feedback from such newly formed secondary objects using radiative hydrodynamic simulations. We compare the results of simulations without any radiative feedback from secondary objects with those where two types of radiative feedback are considered: (i) continuous and (ii) episodic. We find that (i) continuous radiative feedback stabilizes the disc and suppresses further fragmentation, reducing the number of secondary objects formed; (ii) episodic feedback from secondary objects heats and stabilizes the disc when the outburst occurs, but shortly after the outburst stops, the disc becomes unstable and fragments again. However, fewer secondary objects are formed compared to the case without radiative feedback. We also find that the mass growth of secondary objects is mildly suppressed due to the effect of their radiative feedback. However, their mass growth also depends on where they form in the disc and on their subsequent interactions, such that their final masses are not drastically different from the case without radiative feedback. We find that the masses of secondary objects formed by disc fragmentation are from a few MJ to a few 0.1 M⊙. Planets formed by fragmentation tend to be ejected from the disc. We conclude that planetary-mass objects on wide orbits (wide-orbit planets) are unlikely to form by disc fragmentation. Nevertheless, disc fragmentation may be a significant source of free-floating planets and brown dwarfs.

  6. Working characteristics of external distributed feedback polymer lasers with varying waveguiding structures

    Science.gov (United States)

    Huang, Wenbin; Shen, Su; Pu, Donglin; Wei, Guojun; Ye, Yan; Peng, Changsi; Chen, Linsen

    2015-12-01

    We report the fabrication and characterization of second-order external distributed feedback (DFB) lasers based on blue-emitting polymer poly (9, 9-dioctyl-fluorene) (PFO). The relief grating prepared in the photo-resist layer on top of the gain medium was directly employed as the resonator. The effect of various structural parameters including the thickness of the active film, the thickness of the residue layer, and the depth of the relief grating on performance of these polymer lasers was investigated. An analytical approach based on the slab waveguiding theory and the Bragg condition was developed to accurately determine the lasing wavelength. We found that laser threshold increases monotonously as the thickness of the residue layer increases. The presence of the residue layer between the relief grating and the organic semiconductor layer weakens the strength of light coupling between the two layers, leading to a decreased gain for the specific lasing mode. The lowest laser threshold level of 80 μJ cm-2 was obtained when the thickness of the gain medium was around 250 nm, indicating an optimum balance between light feedback provided by the grating and optical amplification in the organic semiconductor. Our results not only provide insights into working mechanisms of external DFB polymer lasers, but also design rules for fabricating them.

  7. Voltage tunable multiple quantum well distributed feedback filter with an electron beam written Schottky grating

    Science.gov (United States)

    Zia, O.; Bhattacharya, P. K.; Singh, J.; Brock, T.

    1994-08-01

    A novel optoelectronic filter voltage-tunable characteristics has been developed and implemented in a multiquantum well waveguide device. By virtue of the quantum-confined Stark effect, the refractive index in quantum wells at the periphery of a guiding region can be given a periodicity in the guiding direction by application of a bias on an electron-beam patterned Schottky grating atop the guide. If the period of the Schottky grating and associated index profile satisfies the Bragg condition, as in a resonant distributed feedback structure, band-reject filtering results. Aftering the bias on the Schottky grating changes the refractive index in the wells, thereby providing tunability of the wavelength at which Bragg diffraction occurs.

  8. Reconfigurable Optical Signal Processing Based on a Distributed Feedback Semiconductor Optical Amplifier.

    Science.gov (United States)

    Li, Ming; Deng, Ye; Tang, Jian; Sun, Shuqian; Yao, Jianping; Azaña, José; Zhu, Ninghua

    2016-01-27

    All-optical signal processing has been considered a solution to overcome the bandwidth and speed limitations imposed by conventional electronic-based systems. Over the last few years, an impressive range of all-optical signal processors have been proposed, but few of them come with reconfigurability, a feature highly needed for practical signal processing applications. Here we propose and experimentally demonstrate an analog optical signal processor based on a phase-shifted distributed feedback semiconductor optical amplifier (DFB-SOA) and an optical filter. The proposed analog optical signal processor can be reconfigured to perform signal processing functions including ordinary differential equation solving and temporal intensity differentiation. The reconfigurability is achieved by controlling the injection currents. Our demonstration provitdes a simple and effective solution for all-optical signal processing and computing.

  9. Reconfigurable Optical Signal Processing Based on a Distributed Feedback Semiconductor Optical Amplifier

    Science.gov (United States)

    Li, Ming; Deng, Ye; Tang, Jian; Sun, Shuqian; Yao, Jianping; Azaña, José; Zhu, Ninghua

    2016-01-01

    All-optical signal processing has been considered a solution to overcome the bandwidth and speed limitations imposed by conventional electronic-based systems. Over the last few years, an impressive range of all-optical signal processors have been proposed, but few of them come with reconfigurability, a feature highly needed for practical signal processing applications. Here we propose and experimentally demonstrate an analog optical signal processor based on a phase-shifted distributed feedback semiconductor optical amplifier (DFB-SOA) and an optical filter. The proposed analog optical signal processor can be reconfigured to perform signal processing functions including ordinary differential equation solving and temporal intensity differentiation. The reconfigurability is achieved by controlling the injection currents. Our demonstration provitdes a simple and effective solution for all-optical signal processing and computing.

  10. First operation of a powerful FEL with two-dimensional distributed feedback

    CERN Document Server

    Agarin, N V; Bobylev, V B; Ginzburg, N S; Ivanenko, V G; Kalinin, P V; Kuznetsov, S A; Peskov, N Yu; Sergeev, A S; Sinitsky, S L; Stepanov, V D

    2000-01-01

    A W-band (75 GHz) FEL of planar geometry driven by a sheet electron beam was realised using the pulse accelerator ELMI (0.8 MeV/3 kA/5 mu s). To provide the spatial coherence of radiation from different parts of the electron beam with a cross-section of 0.4x12 cm two-dimensional distributed feedback systems have been employed using a 2-D Bragg resonator of planar geometry. The resonator consisted of two 2-D Bragg reflectors separated by a regular waveguide section. The total energy in the microwave pulse of microsecond duration was 100 J corresponding to a power of approx 100 MW. The main component of the FEL radiation spectrum was at 75 GHz that corresponded to the zone of effective Bragg reflection found from 'cold' microwave testing of the resonator. The experimental data compared well with the results of theoretical analysis.

  11. Blue surface-emitting distributed feedback lasers based on TPD-doped films.

    Science.gov (United States)

    Calzado, Eva M; Villalvilla, Jose M; Boj, Pedro G; Quintana, Jose A; Postigo, Pablo A; Díaz-García, María A

    2010-01-20

    Single-mode second-order distributed feedback (DFB) lasers with low threshold, based on polystyrene films doped with 30 wt. % of the hole-transporting organic molecule N,N'-bis (3-methylphenyl)-N,N'-diphenylbenzidine (TPD) are reported. The laser emission wavelength was tuned between 415 and 427 nm by film thickness variation. The effectiveness of the DFB grating in improving the laser performance is evidenced by the observation of linewidths and laser thresholds lower than those of the amplified spontaneous emission characteristics shown by films without gratings. The use of holographic lithography as the technique for grating recording has allowed us to prepare large samples in a fast, versatile, and simple manner.

  12. Stabilization of Nonuniform Euler-Bernoulli Beam with Locally Distributed Feedbacks

    Institute of Scientific and Technical Information of China (English)

    Xian-bing CAO; Qing-xu YAN

    2012-01-01

    In this article,we study the stabilization problem of a nonuniform Euler-Bernoulli beam with locally distributed feedbacks.Firstly,using the semi-group theory,we establish the well-posedness of the associated closed loop system.Then by proving the uniqueness of the solution of a related ordinary differential equations,we derive the asymptotic stability of the closed loop system. Finally,by means of the piecewise frequency domain multiplier method,we prove that the corresponding closed loop system can be exponentially stabilized by only one of the two distributed feedback controls proposed in this paper.

  13. Effects of Vehicle Number Feedback in Multi-Route Intelligent Traffic Systems

    Science.gov (United States)

    Dong, Chuanfei; Ma, Xu; Wang, Binghong

    We first study dynamics of traffic flow with real-time information and the influence of a new feedback strategy named Vehicle Number Feedback Strategy (VNFS) in a multi-route scenario in which dynamic information can be generated and displayed on the board (the board refers to a variable message sign where information on the routes is displayed) to guide road users to make a choice. In a multi-route scenario, our model incorporates the effects of adaptability into the cellular automaton models of traffic flow and simulation results adopting vehicle number feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other three information feedback strategies, i.e. Travel Time Feedback Strategy (TTFS), Mean Velocity Feedback Strategy (MVFS) and Congestion Coefficient Feedback Strategy (CCFS). We also discuss the influence of expected arrival rate (Vp) at the entrance on the average flux of each route, and we find that the flux adopting VNFS is always the largest at each Vp value among these four feedback strategies.

  14. The effectiveness of EEG-feedback on attention, impulsivity and EEG: a sham feedback controlled study.

    NARCIS (Netherlands)

    Logemann, H.N.; Lansbergen, M.M.; Os, T.W. Van; Bocker, K.B.; Kenemans, J.L.

    2010-01-01

    EEG-feedback, also called neurofeedback, is a training procedure aimed at altering brain activity, and is used as a treatment for disorders like Attention Deficit/Hyperactivity Disorder (ADHD). Studies have reported positive effects of neurofeedback on attention and other dependent variables.

  15. The effectiveness of EEG-feedback on attention, impulsivity and EEG : A sham feedback controlled study

    NARCIS (Netherlands)

    Logemann, H. N. Alexander; Lansbergen, Marieke M.; Van Os, Titus W. D. P.; Bocker, Koen B. E.; Kenemans, J. Leon

    2010-01-01

    EEG-feedback, also called neurofeedback, is a training procedure aimed at altering brain activity, and is used as a treatment for disorders like Attention Deficit/Hyperactivity Disorder (ADHD). Studies have reported positive effects of neurofeedback on attention and other dependent variables.

  16. "I Really Need Feedback to Learn:" Students' Perspectives on the Effectiveness of the Differential Feedback Messages

    Science.gov (United States)

    Lipnevich, Anastasiya A.; Smith, Jeffrey K.

    2009-01-01

    The current study examined students' perceptions of the effects of different forms of instructional feedback on their performance, motivation, and emotion. Forty-nine students attending an eastern US university participated in focus group discussions. The groups explored students' reactions to grades, praise, and computer versus instructor…

  17. The effectiveness of EEG-feedback on attention, impulsivity and EEG: a sham feedback controlled study.

    NARCIS (Netherlands)

    Logemann, H.N.; Lansbergen, M.M.; Os, T.W. Van; Bocker, K.B.; Kenemans, J.L.

    2010-01-01

    EEG-feedback, also called neurofeedback, is a training procedure aimed at altering brain activity, and is used as a treatment for disorders like Attention Deficit/Hyperactivity Disorder (ADHD). Studies have reported positive effects of neurofeedback on attention and other dependent variables. Howeve

  18. The effectiveness of EEG-feedback on attention, impulsivity and EEG : A sham feedback controlled study

    NARCIS (Netherlands)

    Logemann, H. N. Alexander; Lansbergen, Marieke M.; Van Os, Titus W. D. P.; Bocker, Koen B. E.; Kenemans, J. Leon

    2010-01-01

    EEG-feedback, also called neurofeedback, is a training procedure aimed at altering brain activity, and is used as a treatment for disorders like Attention Deficit/Hyperactivity Disorder (ADHD). Studies have reported positive effects of neurofeedback on attention and other dependent variables. Howeve

  19. Effects of intrinsic motivation on feedback processing during learning.

    Science.gov (United States)

    DePasque, Samantha; Tricomi, Elizabeth

    2015-10-01

    Learning commonly requires feedback about the consequences of one's actions, which can drive learners to modify their behavior. Motivation may determine how sensitive an individual might be to such feedback, particularly in educational contexts where some students value academic achievement more than others. Thus, motivation for a task might influence the value placed on performance feedback and how effectively it is used to improve learning. To investigate the interplay between intrinsic motivation and feedback processing, we used functional magnetic resonance imaging (fMRI) during feedback-based learning before and after a novel manipulation based on motivational interviewing, a technique for enhancing treatment motivation in mental health settings. Because of its role in the reinforcement learning system, the striatum is situated to play a significant role in the modulation of learning based on motivation. Consistent with this idea, motivation levels during the task were associated with sensitivity to positive versus negative feedback in the striatum. Additionally, heightened motivation following a brief motivational interview was associated with increases in feedback sensitivity in the left medial temporal lobe. Our results suggest that motivation modulates neural responses to performance-related feedback, and furthermore that changes in motivation facilitate processing in areas that support learning and memory.

  20. The need for faculty training programs in effective feedback provision

    Directory of Open Access Journals (Sweden)

    Al Wahbi A

    2014-08-01

    Full Text Available Abdullah Al Wahbi1,2 1King Saud University for Health Sciences, 2King Abdulaziz Medical City, Division of Vascular Surgery, Department of Surgery, Riyadh, Saudi Arabia Abstract: An important aspect of professional teaching practice is a practitioner's ability to critically evaluate the performances of subordinates for whom he or she is responsible. This is a common practice within social sciences as well as for professionals from applied specialties. The literature on professional clinical expertise identifies reflective practice as perfect when they are thoroughly accepted by practitioners. In health-related professions, critical reflection in the form of feedback that serves as the bridge between theory and practice is endorsed. The aims and objectives of this study were directed toward the application of a mixed methodology approach in order to evaluate the requirements for a feedback training program and to detect the present feedback provision skills of clinical mentors in practice. The quantitative analysis measured the effectiveness of clinical teachers' feedback in order to understand whether their understanding of and skills for giving feedback to promote students were adequate. On the other hand, the qualitative methods explored self-perceptions of feedback skills and efficacy in enabling students to improve their clinical practice. Effective feedback from faculty and the learner provides a useful and meaningful experience for absorbing knowledge and critical thinking into clinical practice. Nonadherence and limited expertise of mentors in giving feedback are the main themes of this study, and were evaluated and acknowledged through systematic analysis. Keywords: clinical mentors, feedback mechanism, feedback proficiency 

  1. [Positive feedback is not fully effective in all situations].

    Science.gov (United States)

    Yamaura, Kazuho; Horishita, Tomoko; Kanayama, Masaki

    2013-02-01

    This experimental study investigated how leader-member exchange (LMX) and positive feedback pertinent to the goal is related to subordinates' responsibility, assessment of their supervisors, and feeling of being implicitly scolded, to elaborate and confirm the findings of Bezuijen et al. (2010). We hypothesized that positive feedback pertinent to the goal would be more effective compared to unrelated feedback. Secondly, we hypothesized that this effect would be moderated by the quality of LMX. Undergraduate students (29 male, 51 female; 20.4 +/- .63 yrs) participated as subordinates in an experiment consisting of two sessions. The results supported our hypotheses. We found that the positive feedback pertinent to the goal led to increased levels of responsibility. This effect was greater under high-quality LMX conditions, but was inhibited under low-quality LMX conditions. In the high-quality LMX condition, subordinates who did not get any feedback decreased their responsibility, gave lower supervisor assessment ratings, and felt more strongly scolded than under conditions where they received feedback. We discussed the importance of the combination of the quality of the relationship and positive feedback related to the goal, and provided directions for future research.

  2. Are there rapid feedback effects on Approximate Number System acuity?

    Science.gov (United States)

    Lindskog, Marcus; Winman, Anders; Juslin, Peter

    2013-01-01

    Humans are believed to be equipped with an Approximate Number System (ANS) that supports non-symbolic representations of numerical magnitude. Correlations between individual measures of the precision of the ANS and mathematical ability have raised the question of whether the precision can be improved by feedback training. A study (DeWind and Brannon, 2012) reported improvement in discrimination precision occurring within 600-700 trials of feedback, suggesting ANS malleability with rapidly improving acuity in response to feedback. We tried to replicate the rapid improvement in a control group design, while controlling for the use of perceptual cues. The results indicate no learning effects, but a minor constant advantage for the feedback group. The measures of motivation suggest that feedback has a positive effect on motivation and that the difference in discrimination is due to the greater motivation of participants with feedback. These results suggest that at least for adults the number sense may not respond to feedback in the short-term.

  3. Are there rapid feedback effects on Approximate Number System acuity?

    Directory of Open Access Journals (Sweden)

    Marcus eLindskog

    2013-06-01

    Full Text Available Humans are believed to be equipped with an Approximate Number System (ANS that supports non-symbolic representations of numerical magnitude. Correlations between individual measures of the precision of the ANS and mathematical ability have raised the question of whether the precision can be improved by feedback training. A study (DeWind & Brannon, 2012 reported improvement in discrimination precision occurring within 600-700 trials of feedback, suggesting ANS malleability with rapidly improving acuity in response to feedback. We tried to replicate the rapid improvement in a control group design, while controlling for the use of perceptual cues. The results indicate no learning effects, but a minor constant advantage for the feedback group. The measures of motivation suggest that feedback has a positive effect on motivation and that the difference in discrimination is due to the greater motivation of participants with feedback. These results suggest that at least for adults the number sense may not respond to feedback in the short-term.

  4. Optimized Distributed Feedback Dye Laser Sensor for Real-Time Monitoring of Small Molecule Diffusion

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Smith, Cameron; Dufva, Martin

    2014-01-01

    Nanoimprinted distributed feedback dye laser sensors featuring multilayer slab waveguides are presented. A simple yet precise analytical model is used to optimize the lasers in order to give highest sensitivity and it is found that the thickness of a high index TiO2 top layer is the most importan...

  5. Single-mode biological distributed feedback lasers based on vitamin B2 doped gelatin

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Maier-Flaig, F.; Lemmer, U.

    Biological second-order distributed feedback (DFB) lasers are presented. Riboflavin (vitamin B2) doped gelatin as active material is spin-coated onto nanoimprinted polymer with low refractive index. DFB grating periods of 368 nm and 384 nm yield laser emission at 543 nm and 562 nm, respectively....

  6. Single-mode biological distributed feedback lasers based on vitamin B2 doped gelatin

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Maier-Flaig, F.; Lemmer, U.

    Biological second-order distributed feedback (DFB) lasers are presented. Riboflavin (vitamin B2) doped gelatin as active material is spin-coated onto nanoimprinted polymer with low refractive index. DFB grating periods of 368 nm and 384 nm yield laser emission at 543 nm and 562 nm, respectively....

  7. Narrow-Linewidth Distributed Feedback Channel Waveguide Laser in Al$_2$O$_3$:Er$^{3+}$

    NARCIS (Netherlands)

    Bernhardi, E.H.; Agazzi, L.; Wörhoff, K.; Ridder, de R.M.; Pollnau, M.; Pozo, J.; Mortensen, M.; Urbach, P.; Leijtens, X.; Yousefi, M.

    2010-01-01

    We report on the fabrication and characterization of a distributed feedback channel waveguide laser in erbium-doped aluminium oxide on a standard thermally oxidized silicon substrate. Holographically-written surface-relief Bragg gratings have been integrated with the aluminium oxide waveguides via r

  8. Distribution of Feedback among Teacher and Students in Online Collaborative Learning in Small Groups

    Science.gov (United States)

    Coll, Cesar; Rochera, Maria Jose; de Gispert, Ines; Diaz-Barriga, Frida

    2013-01-01

    This study explores the characteristics and distribution of the feedback provided by the participants (a teacher and her students) in an activity organized inside a collaborative online learning environment. We analyse 853 submissions made by two groups of graduate students and their teacher (N1 = 629 & N2 = 224) involved in the collaborative…

  9. Linewidth broadening in a distributed feedback laser integrated with a semiconductor optical amplifier

    DEFF Research Database (Denmark)

    Champagne, A.; Camel, J.; Maciejko, R.

    2002-01-01

    The problem of the linewidth degradation in systems using distributed-feedback lasers together with strained-layer multi-quantum-well semiconductor optical amplifiers (SOAs) is examined. A modified expression for the linewidth in the case of antireflection-coated SOA output facets is derived...

  10. PROVIDING THE STUDENTS WITH EFFECTIVE FEEDBACK IN THE WRITING PROCESS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    This paper focuses on providing effective feedback for the students in the writing process.Excessivemarking is defective as it reduces their motivation,whereas minimal marking is recommended as itimproves their inner drive for writing.In addition,there are other forms of feedback,such as peerfeedback,comments and face-to-face discussions.The students are required to act on the feedback totheir own advantage.It has been proved that the proposed correcting method is time-saving,chal-lenging and efficient.

  11. Information Feedback and Mass Media Effects in Cultural Dynamics

    OpenAIRE

    González-Avella, Juan Carlos; Cosenza, Mario G.; Klemm, Konstantin; Eguíluz, Víctor M; San Miguel, Maxi

    2007-01-01

    We study the effects of different forms of information feedback associated with mass media on an agent-agent based model of the dynamics of cultural dissemination. In addition to some processes previously considered, we also examine a model of local mass media influence in cultural dynamics. Two mechanisms of information feedback are investigated: (i) direct mass media influence, where local or global mass media act as an additional element in the network of interactions of each agent, and (i...

  12. Information feedback and mass media effects in cultural dynamics

    OpenAIRE

    González-Avella, Juan Carlos; Mario G. Cosenza; Klemm, Konstantin; Eguíluz, Víctor M.; San Miguel, Maxi

    2007-01-01

    We study the effects of different forms of information feedback associated with mass media on an agent-agent based model of the dynamics of cultural dissemination. In addition to some processes previously considered, we also examine a model of local mass media influence in cultural dynamics. Two mechanisms of information feedback are investigated: (i) direct mass media influence, where local or global mass media act as an additional element in the network of interactions of each agent, and (i...

  13. Distributed feedback terahertz frequency quantum cascade lasers with dual periodicity gratings

    CERN Document Server

    Castellano, F; Li, L H; Pitanti, A; Tredicucci, A; Linfield, E H; Davies, A G; Vitiello, M S

    2016-01-01

    We have developed terahertz frequency quantum cascade lasers that exploit a double-periodicity distributed feedback grating to control the emission frequency and the output beam direction independently. The spatial refractive index modulation of the gratings necessary to provide optical feedback at a fixed frequency and, simultaneously, a far-field emission pattern centered at controlled angles, was designed through use of an appropriate wavevector scattering model. Single mode THz emission at angles tuned by design between 0{\\deg} and 50{\\deg} was realized, leading to an original phase-matching approach, lithographically independent, for highly collimated THz QCLs.

  14. The Effect of Feedback Style on Feedback Seeking Behaviors: an Examination of Perceived Competence

    OpenAIRE

    Stimpson, Emily Carol

    1999-01-01

    Research in the area of feedback seeking behaviors (Ashford & Cummings, 1983) has failed to examine the impact of a supervisorâ s feedback style on a subordinateâ s subsequent feedback seeking. This is an important area for investigation due to the positive relationship between feedback seeking and performance. Deci and Ryanâ s cognitive evaluation theory suggests that intrinsic motivation may be an important mediator between feedback style and FSB in that feedback ...

  15. THE EFFECTS OF MODELING AND FEEDBACK VARIABLES ON THE ACQUISITION OF A COMPLEX TEACHING STRATEGY.

    Science.gov (United States)

    ORME, MICHAEL E.J.; AND OTHERS

    THE RELATIVE EFFECTIVENESS OF SIX MODES OF TRAINING TEACHERS TO USE PROBING QUESTIONS WAS INVESTIGATED. THE MODES INVOLVED SYMBOLIC MODELING, PERCEPTUAL MODELING, OR BOTH, COUPLED WITH FEEDBACK. AFTER RATINGS OF PERTINENT BEHAVIOR IN A 5-MINUTE LESSON WERE COLLECTED AS PRETRAINING MEASURES, STANFORD TEACHER INTERNS WERE RANDOMLY DISTRIBUTED AMONG…

  16. Different Sequences of Feedback Types: Effectiveness, Attitudes, and Preferences

    Science.gov (United States)

    Wanchid, Raveewan

    2015-01-01

    The purposes of this research were to: 1) to compare the effects of different sequences of feedback types on the students' writing ability and their effect size; 2) to compare the effects of the levels of general English proficiency (high, moderate, and low) on the students' writing ability and their effect size; 3) to investigate the interaction…

  17. Effects of changes in climate on landscape and regional processes, and feedbacks to the climate system.

    Science.gov (United States)

    Callaghan, Terry V; Björn, Lars Olof; Chernov, Yuri; Chapin, Terry; Christensen, Torben R; Huntley, Brian; Ims, Rolf A; Johansson, Margareta; Jolly, Dyanna; Jonasson, Sven; Matveyeva, Nadya; Panikov, Nicolai; Oechel, Walter; Shaver, Gus; Schaphoff, Sibyll; Sitch, Stephen

    2004-11-01

    Biological and physical processes in the Arctic system operate at various temporal and spatial scales to impact large-scale feedbacks and interactions with the earth system. There are four main potential feedback mechanisms between the impacts of climate change on the Arctic and the global climate system: albedo, greenhouse gas emissions or uptake by ecosystems, greenhouse gas emissions from methane hydrates, and increased freshwater fluxes that could affect the thermohaline circulation. All these feedbacks are controlled to some extent by changes in ecosystem distribution and character and particularly by large-scale movement of vegetation zones. Indications from a few, full annual measurements of CO2 fluxes are that currently the source areas exceed sink areas in geographical distribution. The little available information on CH4 sources indicates that emissions at the landscape level are of great importance for the total greenhouse balance of the circumpolar North. Energy and water balances of Arctic landscapes are also important feedback mechanisms in a changing climate. Increasing density and spatial expansion of vegetation will cause a lowering of the albedo and more energy to be absorbed on the ground. This effect is likely to exceed the negative feedback of increased C sequestration in greater primary productivity resulting from the displacements of areas of polar desert by tundra, and areas of tundra by forest. The degradation of permafrost has complex consequences for trace gas dynamics. In areas of discontinuous permafrost, warming, will lead to a complete loss of the permafrost. Depending on local hydrological conditions this may in turn lead to a wetting or drying of the environment with subsequent implications for greenhouse gas fluxes. Overall, the complex interactions between processes contributing to feedbacks, variability over time and space in these processes, and insufficient data have generated considerable uncertainties in estimating the net

  18. Radiative Feedback Effects during Cosmic Reionization

    Science.gov (United States)

    Sullivan, David; Iliev, Ilian T.

    2016-10-01

    We present coupled radiation hydrodynamical simulations of the epoch of reionization, aimed at probing self-feedback on galactic scales. Unlike previous works, which assume a (quasi) homogeneous UV background, we self-consistently evolve both the radiation field and the gas to model the impact of previously unresolved processes such as spectral hardening and self-shielding. We find that the characteristic halo mass with a gas fraction half the cosmic mean, Mc (z), a quantity frequently used in semi-analytical models of galaxy formation, is significantly larger than previously assumed. While this results in an increased suppression of star formation in the early Universe, our results are consistent with the extrapolated stellar abundance matching models from Moster et al. 2013.

  19. Effective feedback strategies for teaching in pediatric and adolescent gynecology.

    Science.gov (United States)

    Kaul, Paritosh; Gong, Jennifer; Guiton, Gretchen

    2014-08-01

    The clinical setting of pediatric and adolescent gynecology poses complex tasks for the physician with its numerous procedures and the communication demands of interacting with an adolescent and/or guardian. Needless to say, teaching within this setting is highly demanding. Regardless of the level of learner or the professional role (e.g., nurse, medical student, resident, physician assistant) represented, clinical teaching requires that the instructor provide feedback in ways that benefit the student. Recent research on feedback suggests a more complex understanding of feedback than in the past. This article highlights key research and its implication for effective feedback by presenting a three part framework; know your learner, understand what is to be learned, and plan for improvement.

  20. SAFCM: A Security-Aware Feedback Control Mechanism for Distributed Real-Time Embedded Systems

    DEFF Research Database (Denmark)

    Ma, Yue; Jiang, Wei; Sang, Nan

    2012-01-01

    -time systems, a multi-input multi-output feedback loop is designed and a model predictive controller is deployed based on an equation model that describes the dynamic behavior of the DRE systems. This control loop uses security level scaling to globally control the CPU utilization and security performance......Distributed Real-time Embedded (DRE) systems are facing great challenges in networked, unpredictable and especially unsecured environments. In such systems, there is a strong need to enforce security on distributed computing nodes in order to guard against potential threats, while satisfying...... the real-time requirements. This paper proposes a Security-Aware Feedback Control Mechanism (SAFCM) which has the ability to dynamically change the security level to guarantee soft real-time requirements and make the security protection as strong as possible. In order to widely support distributed real...

  1. An Investigation of the Effects of Three Post-writing Methods: Focused Feedback, Learner-oriented Focused Feedback, and No Feedback

    Directory of Open Access Journals (Sweden)

    Mozhgan Jamali

    2014-09-01

    Full Text Available There have been inconclusive results regarding the issue of feedback and no feedback to student compositions. The present study investigated potential differences in the effect, on writing accuracy, of focused meta-linguistic feedback, learner-oriented focused meta-linguistic feedback, and mere writing practice on overall accuracy in Iranian EFL writings. Because of dramatic student attrition and two failures in the data collection phase which was due to lack of student commitment to performing the tasks, the study involved three groups: a experimental A (33→9 who wrote on topics, received feedback, and kept edit logs and error tally sheets; b experimental B (33→7 who only received feedback; and c control (33→6 who merely wrote on topics. The results indicated that all the three methods are almost equally ineffective to accuracy improvement of student writings in the targeted areas, thus refuting claims for the effectiveness of both feedback and no feedback methods. Keywords: focused CF; meta-linguistic feedback; writing accuracy

  2. Social closeness and feedback modulate susceptibility to the framing effect.

    Science.gov (United States)

    Sip, Kamila E; Smith, David V; Porcelli, Anthony J; Kar, Kohitij; Delgado, Mauricio R

    2015-01-01

    Although we often seek social feedback (SFB) from others to help us make decisions, little is known about how SFB affects decisions under risk, particularly from a close peer. We conducted two experiments using an established framing task to probe how decision-making is modulated by SFB valence (positive, negative) and the level of closeness with feedback provider (friend, confederate). Participants faced mathematically equivalent decisions framed as either an opportunity to keep (gain frame) or lose (loss frame) part of an initial endowment. Periodically, participants were provided with positive (e.g., "Nice!") or negative (e.g., "Lame!") feedback about their choices. Such feedback was provided by either a confederate (Experiment 1) or a gender-matched close friend (Experiment 2). As expected, the framing effect was observed in both experiments. Critically, an individual's susceptibility to the framing effect was modulated by the valence of the SFB, but only when the feedback provider was a close friend. This effect was reflected in the activation patterns of ventromedial prefrontal cortex and posterior cingulate cortex, regions involved in complex decision-making. Taken together, these results highlight social closeness as an important factor in understanding the impact of SFB on neural mechanisms of decision-making.

  3. Offset quantum-well method for tunable distributed Bragg reflector lasers and electro-absorption modulated distributed feedback lasers

    Institute of Scientific and Technical Information of China (English)

    Qiang Kan; Ying Ding; Lingjuan Zhao; Hongliang Zhu; Fan Zhou; Lufeng Wang; Baojun Wang; Wei Wang

    2005-01-01

    @@ A two-section offset quantum-well structure tunable laser with a tuning range of 7 nm was fabricated using offset quantum-well method. The distributed Bragg reflector (DBR) was realized just by selectively wet etching the multiquantum-well (MQW) layer above the quaternary lower waveguide. A threshold current of 32 mA and an output power of 9 mW at 100 mA were achieved. Furthermore, with this offset structure method, a distributed feedback (DFB) laser was integrated with an electro-absorption modulator (EAM),which was capable of producing 20 dB of optical extinction.

  4. Private versus Public Feedback - The Incentive Effects of Symbolic Awards

    DEFF Research Database (Denmark)

    Gerhards, Leonie; Siemer, Neele

    We experimentally compare the incentive effects of rewarding individuals for outstanding performance publicly versus privately. We implement two real-effort tasks, which differ in how prestigious subjects perceive working on them. In both tasks private and public feedback similarly enhances...... experiment at a secondary school we furthermore compare the incentive effects of different forms of public recognition....

  5. Exploring the Effect of Immediate Video Feedback on Coaching

    Science.gov (United States)

    Suhrheinrich, Jessica; Chan, Janice

    2017-01-01

    Although evidence-based practices for autism spectrum disorders exist, they are often not effectively incorporated into school-based programs, indicating a need for enhanced training strategies for educators. This study examined the effects of immediate video feedback during coaching for teachers and paraprofessionals learning Classroom Pivotal…

  6. Distributed Robust H∞ Consensus Control of Multiagent Systems with Communication Errors Using Dynamic Output Feedback Protocol

    Directory of Open Access Journals (Sweden)

    Xi Yang

    2013-01-01

    Full Text Available This paper studies robust consensus problem for multiagent systems modeled by an identical linear time-invariant system under a fixed communication topology. Communication errors in the transferred data are considered, and only the relative output information between each agent and its neighbors is available. A distributed dynamic output feedback protocol is proposed, and sufficient conditions for reaching consensus with a prescribed H∞ performance are presented. Numerical examples are given to illustrate the theoretical results.

  7. Distributed Cooperative Current-Sharing Control of Parallel Chargers Using Feedback Linearization

    OpenAIRE

    Jiangang Liu; Zhiwu Huang; Jing Wang; Jun Peng; Weirong Liu

    2014-01-01

    We propose a distributed current-sharing scheme to address the output current imbalance problem for the parallel chargers in the energy storage type light rail vehicle system. By treating the parallel chargers as a group of agents with output information sharing through communication network, the current-sharing control problem is recast as the consensus tracking problem of multiagents. To facilitate the design, input-output feedback linearization is first applied to transform the nonidentica...

  8. Multimode distributed feedback laser emission in a dye-doped optically pumped polymer thin-film

    Science.gov (United States)

    Sobel, F.; Gindre, D.; Nunzi, J.-M.; Denis, C.; Dumarcher, V.; Fiorini-Debuisschert, C.; Kretsch, K. P.; Rocha, L.

    2004-11-01

    We report on particular features of thin film distributed feedback (DFB) lasers. Devices are optically pumped using a Lloyd-mirror interferometer. For a given DFB grating period, the number of lasing modes is film thickness dependent. Spectral content of the devices is analysed using planar waveguide theory. An excellent agreement between the theoretical transverse electric mode structure and the laser emission spectrum is found.

  9. High order operation of distributed feedback dye-doped sol-gel silica laser

    Institute of Scientific and Technical Information of China (English)

    Xiaolei Zhu(朱小磊); Dennis Lo(罗荫权)

    2003-01-01

    High order Bragg scattering (M = 2 and M = 3) operations of the distributed feedback dye dopedsol-gel silica lasers are achieved using the second harmonic output of a Nd:YAG laser as the pump. Laserlinewidth of less than 0.06 nm and conversion efficiency of 0.7% for M = 3 and 11% for M = 2 aremeasured. Wavelength tuning of about 15 nm around the emission center has been realized by varyingthe intersection angle.

  10. Electrically tunable terahertz quantum cascade lasers based on a two-sections interdigitated distributed feedback cavity

    Energy Technology Data Exchange (ETDEWEB)

    Turčinková, Dana; Scalari, Giacomo; Beck, Mattias; Faist, Jérôme [ETH Zurich, Institute for Quantum Electronics, Auguste-Piccard-Hof 1, 8093 Zurich (Switzerland); Amanti, Maria Ines [ETH Zurich, Institute for Quantum Electronics, Auguste-Piccard-Hof 1, 8093 Zurich (Switzerland); Univ. Paris Diderot, Lab. Matererk iaux et Phenomenes Quantiques, F-75205 Paris (France)

    2015-03-30

    The continuous electrical tuning of a single-mode terahertz quantum cascade laser operating at a frequency of 3 THz is demonstrated. The devices are based on a two-section interdigitated third-order distributed feedback cavity. The lasers can be tuned of about 4 GHz at a constant optical output power of 0.7 mW with a good far-field pattern.

  11. High frame rate multi-resonance imaging refractometry with distributed feedback dye laser sensor

    OpenAIRE

    2015-01-01

    High frame rate and highly sensitive imaging of refractive index changes on a surface is very promising for studying the dynamics of dissolution, mixing and biological processes without the need for labeling. Here, a highly sensitive distributed feedback (DFB) dye laser sensor for high frame rate imaging refractometry without moving parts is presented. DFB dye lasers are low-cost and highly sensitive refractive index sensors. The unique multi-wavelength DFB laser structure presented here comp...

  12. Private versus Public Feedback - The Incentive Effects of Symbolic Awards

    DEFF Research Database (Denmark)

    Gerhards, Leonie; Siemer, Neele

    subjects' performance compared to the control treatment. Also high ability and a positive interim feedback increase performance. Competitive preferences matter only in the less prestigious task. Subjects' gender and overconfidence can in neither of the tasks explain performance. In a supplementary field......We experimentally compare the incentive effects of rewarding individuals for outstanding performance publicly versus privately. We implement two real-effort tasks, which differ in how prestigious subjects perceive working on them. In both tasks private and public feedback similarly enhances...... experiment at a secondary school we furthermore compare the incentive effects of different forms of public recognition....

  13. Net Metering and Market Feedback Loops: Exploring the Impact of Retail Rate Design on Distributed PV Deployment

    Energy Technology Data Exchange (ETDEWEB)

    Darghouth, Naïm R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wiser, Ryan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Barbose, Galen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Mills, Andrew [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-01-13

    The substantial increase in deployment of customer-sited solar photovoltaics (PV) in the United States has been driven by a combination of steeply declining costs, financing innovations, and supportive policies. Among those supportive policies is net metering, which in most states effectively allows customers to receive compensation for distributed PV generation at the full retail electricity price. The current design of retail electricity rates and the presence of net metering have elicited concerns that the possible under-recovery of fixed utility costs from PV system owners may lead to a feedback loop of increasing retail prices that accelerate PV adoption and further rate increases. However, a separate and opposing feedback loop could offset this effect: increased PV deployment may lead to a shift in the timing of peak-period electricity prices that could reduce the bill savings received under net metering where time-varying retail electricity rates are used, thereby dampening further PV adoption. In this paper, we examine the impacts of these two competing feedback dynamics on U.S. distributed PV deployment through 2050 for both residential and commercial customers, across states. Our results indicate that, at the aggregate national level, the two feedback effects nearly offset one another and therefore produce a modest net effect, although their magnitude and direction vary by customer segment and by state. We also model aggregate PV deployment trends under various rate designs and net-metering rules, accounting for feedback dynamics. Our results demonstrate that future adoption of distributed PV is highly sensitive to retail rate structures. Whereas flat, time-invariant rates with net metering lead to higher aggregate national deployment levels than the current mix of rate structures (+5% in 2050), rate structures with higher monthly fixed customer charges or PV compensation at levels lower than the full retail rate can dramatically erode aggregate customer

  14. The Effects of Computer-Assisted Feedback Strategies in Technology Education: A Comparison of Learning Outcomes

    Science.gov (United States)

    Adams, Ruifang Hope; Strickland, Jane

    2012-01-01

    This study investigated the effects of computer-assisted feedback strategies that have been utilized by university students in a technology education curriculum. Specifically, the study examined the effectiveness of the computer-assisted feedback strategy "Knowledge of Response feedback" (KOR), and the "Knowledge of Correct Responses feedback"…

  15. Effects of Feedback Timing on Second Language Vocabulary Learning: Does Delaying Feedback Increase Learning?

    Science.gov (United States)

    Nakata, Tatsuya

    2015-01-01

    Feedback, or information given to learners regarding their performance, is found to facilitate second language (L2) learning. Research also suggests that the timing of feedback (whether it is provided immediately or after a delay) may affect learning. The purpose of the present study was to identify the optimal feedback timing for L2 vocabulary…

  16. Moderating Material to Compensate the Drawback of High Minor Actinide Containing Transmutation Fuel on the Feedback Effects in SFR Cores

    Directory of Open Access Journals (Sweden)

    Bruno Merk

    2013-01-01

    Full Text Available The use of fine distributed moderating material to enhance the feedback effects and to reduce the sodium void effecting SFRs is described. The drawback on the feedback effects due to the introduction of minor actinides into SFR fuel is analyzed. The possibility of compensation of the effect of the minor actinides on the feedback effects by the use of fine distributed moderating material is demonstrated. The consequences of the introduction of fine distributed moderating material into fuel assemblies with fuel configurations foreseen for minor actinide transmutation are analyzed, and the positive effects on the transmutation efficiency are shown. Finally, the possible increase of the Americium content to improve the transmutation efficiency is discussed, the limit value of Americium is determined, and the possibilities given by an increase of the hydrogen content are analyzed.

  17. Rapid and broad wavelength sweeping of standard telecommunication distributed feedback laser diode.

    Science.gov (United States)

    Njegovec, Matej; Donlagic, Denis

    2013-06-01

    This Letter presents a method for the fast and broad wavelength sweeping of a standard setup of a diode's active region and its immediate vicinity, which contain the diode's optical feedback system. The selective and rapid heating of the active region is possible due to the confinement of the voltage drop to the active diode's region that has submicrometer thickness. Using the presented method and an off-the-shelf telecommunication distributed feedback laser diode, we demonstrate wavelength sweeps in excess of 10 nm that were completed in about 200 ns, while generating average optical power in excess of 50 mW. In spite of high-amplitude current-drive pulses, 6000 h continuous operation of the diode within such an operational regime did not show any significant degradation of the diode's performance.

  18. All-Fiber Configuration Laser Self-Mixing Doppler Velocimeter Based on Distributed Feedback Fiber Laser.

    Science.gov (United States)

    Wu, Shuang; Wang, Dehui; Xiang, Rong; Zhou, Junfeng; Ma, Yangcheng; Gui, Huaqiao; Liu, Jianguo; Wang, Huanqin; Lu, Liang; Yu, Benli

    2016-07-27

    In this paper, a novel velocimeter based on laser self-mixing Doppler technology has been developed for speed measurement. The laser employed in our experiment is a distributed feedback (DFB) fiber laser, which is an all-fiber structure using only one Fiber Bragg Grating to realize optical feedback and wavelength selection. Self-mixing interference for optical velocity sensing is experimentally investigated in this novel system, and the experimental results show that the Doppler frequency is linearly proportional to the velocity of a moving target, which agrees with the theoretical analysis commendably. In our experimental system, the velocity measurement can be achieved in the range of 3.58 mm/s-2216 mm/s with a relative error under one percent, demonstrating that our novel all-fiber configuration velocimeter can implement wide-range velocity measurements with high accuracy.

  19. Low-Threshold Conjugated Polymer Distributed Feedback Lasers on InP Substrate

    Institute of Scientific and Technical Information of China (English)

    ZHANG Su-Mei; ZHANG Ding-Ke; MA Dong-Ge

    2008-01-01

    We demonstrate a low threshold polymer sofid state thin-film distributed feedback (DFB) laser on an InP substrate with the DFB structure.The used gain medium is conjugated polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene](MEH-PPV) doped polystyrene (PS) and formed by drop-coating method.The second order Bragg scattering region on the InP substrate gave rise to strong feedback,thus a lazing emission at 638.9nm with a line width of 1.2nm is realized when pumped by a 532nm frequency-doubled Nd:YAG pulsed laser.The devices show a laser threshold as low as 7n J/pulse.

  20. Evaluating Writing: Effects of Feedback on Revision.

    Science.gov (United States)

    Chaudron, Craig

    The effect of evaluation method on English as second language (ESL) learners' revisions of their compositions was investigated. Teacher comments, peer evaluations, and English-speaking peer reformulations were compared. Judges rated the revised compositions of 9 advanced and 14 intermediate college ESL students using the ESL Composition Profile.…

  1. Significant Performance Advantage of Electroabsorption Modulator Integrated Distributed Feedback Laser (EML) Transmitter in Transporting Multicarrier QAM Signals

    NARCIS (Netherlands)

    Chand, Naresh; Bakker, Laurens; Veen, van Dora; Yadvish, Robert D.

    2001-01-01

    Data are presented that show that, for transporting quadrature amplitude modulated (QAM) radiofrequency (RF) subcarriers in suboctave frequency range, electroabsorption modulator integrated distributed feedback lasers (EMLs) can he modulated with significantly higher (2.5 times) modulation index wit

  2. GaSb-based single-mode distributed feedback lasers for sensing (Conference Presentation)

    Science.gov (United States)

    Gupta, James A.; Bezinger, Andrew; Lapointe, Jean; Poitras, Daniel; Aers, Geof C.

    2017-02-01

    GaSb-based tunable single-mode diode lasers can enable rapid, highly-selective and highly-sensitive absorption spectroscopy systems for gas sensing. In this work, single-mode distributed feedback (DFB) laser diodes were developed for the detection of various trace gases in the 2-3.3um range, including CO2, CO, HF, H2S, H2O and CH4. The lasers were fabricated using an index-coupled grating process without epitaxial regrowth, making the process significantly less expensive than conventional DFB fabrication. The devices are based on InGaAsSb/AlGaAsSb separate confinement heterostructures grown on GaSb by molecular beam epitaxy. DFB lasers were produced using a two step etch process. Narrow ridge waveguides were first defined by optical lithography and etched into the semiconductor. Lateral gratings were then defined on both sides of the ridge using electron-beam lithography and etched to produce the index-grating. Effective index modeling was used to optimize the ridge width, etch depths and the grating pitch to ensure single-lateral-mode operation and adequate coupling strength. The effective index method was further used to simulate the DFB laser emission spectrum, based on a transfer matrix model for light transmission through the periodic structure. The fabricated lasers exhibit single-mode operation which is tunable through the absorption features of the various target gases by adjustment of the drive current. In addition to the established open-path sensing applications, these devices have great potential for optoelectronic integrated gas sensors, making use of integrated photodetectors and possibly on-chip Si photonics waveguide structures.

  3. The effect of video-assisted oral feedback versus oral feedback on surgical communicative competences in undergraduate training.

    Science.gov (United States)

    Ruesseler, M; Sterz, J; Bender, B; Hoefer, S; Walcher, F

    2017-08-01

    Feedback can significantly improve future performance. Reviewing one's performance by video is discussed as useful adjunct to debriefing, particularly for non-technical skills. Communicative competencies are an essential part of daily clinical practice; thus should be taught and assessed during undergraduate training. The aim of this study was to compare the educational value of video-assisted feedback versus oral feedback in communicative competencies in the surgical context. Fourth-year medical students completed a 210-min training unit of 'taking patient's history and obtaining informed consents prior to surgery' using role plays. Oral feedback was received directly thereafter using agenda-led, outcome-based guidelines (ALOBA). In the study group, the role plays were video-taped and reviewed thereafter. Afterwards, students completed two OSCE stations, where they were assessed regarding their communicative competencies and the content of the clinical scenario. One-hundred students (49 receiving video-assisted feedback, 51 oral) participated in the study. Those receiving video-assisted feedback performed significantly better in overall score in both OSCE stations (p communicative competencies at taking patient history (p = 0.029 or better), and in 2 of 5 items at obtaining informed consent (p = 0.008, <0.001). The educational effect size for both tasks was large. Using our methodology, video-assisted feedback offered a significant educational benefit over oral feedback alone during a simulated patient encounter in a surgical context.

  4. Nanoimprinted distributed feedback dye laser sensors for high frame rate refractometric imaging of dissolution and fluid flow

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Sørensen, Kristian Tølbøl; Gade, Carsten;

    2015-01-01

    High frame rate refractometric dissolution and fluid flow monitoring in one and two dimensions of space with distributed feedback dye laser sensors is presented. The sensors provide both low detection limits and high spatial resolution. © 2015 OSA.......High frame rate refractometric dissolution and fluid flow monitoring in one and two dimensions of space with distributed feedback dye laser sensors is presented. The sensors provide both low detection limits and high spatial resolution. © 2015 OSA....

  5. Electricity Distribution Effectiveness

    Directory of Open Access Journals (Sweden)

    Waldemar Szpyra

    2015-12-01

    Full Text Available This paper discusses the basic concepts of cost accounting in the power industry and selected ways of assessing the effectiveness of electricity distribution. The results of effectiveness analysis of MV/LV distribution transformer replacement are presented, and unit costs of energy transmission through various medium-voltage line types are compared. The calculation results confirm the viability of replacing transformers manufactured before 1975. Replacing transformers manufactured after 1975 – only to reduce energy losses – is not economically justified. Increasing use of a PAS type line for energy transmission in local distribution networks is reasonable. Cabling these networks under the current calculation rules of discounts for excessive power outages is not viable, even in areas particularly exposed to catastrophic wire icing.

  6. Four distributed feedback laser array integrated with multimode-interference and semiconductor optical amplifier

    Institute of Scientific and Technical Information of China (English)

    Ma Li; Zhu Hong-Liang; Liang Song; Zhao Ling-Juan; Chen Ming-Hua

    2013-01-01

    Monolithic integration of four 1.55-μm-range InGaAsP/InP distributed feedback (DFB) lasers using varied ridge width with a 4 × 1-multimode-interference (MMI) optical combiner and a semiconductor optical amplifier (SOA) is demonstrated.The average output power and the threshold current are 1.8 mW and 35 mA,respectively,when the injection current of the SOA is 100 mA,with a side mode suppression ratio (SMSR) exceeding 40 dB.The four channels have a 1-nm average channel spacing and can operate separately or simultaneously.

  7. Nanoimprinted distributed feedback lasers comprising TiO2 thin films

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Smith, Cameron; Leung, Michael C.

    2013-01-01

    , have their sensor sensitivity enhanced by a factor of up to five via the evaporation of a titanium dioxide (TiO2) waveguiding layer. The influence of the TiO2 layer thickness on the device sensitivity is analyzed with a simple model that accurately predicts experimentally measured wavelength shifts......Design guidelines for optimizing the sensing performance of nanoimprinted second order distributed feedback dye lasers are presented. The guidelines are verified by experiments and simulations. The lasers, fabricated by UV-nanoimprint lithography into Pyrromethene doped Ormocomp thin films on glass...

  8. Analysis of tunable picosecond pulse generation from a distributed feedback Ti:sapphire laser

    Institute of Scientific and Technical Information of China (English)

    Hong Zhi; Yao Xiao-Ke

    2004-01-01

    A distributed feedback Ti:sapphire laser (DFTL) pumped by a 532nm Q-switched pulse is proposed for the generation of tunable picosecond pulses. With coupled rate equation model, the temporal characteristics of DFTL are obtained. The numerical solutions show that the DFTL pulse with a 50-ps pulse duration and as much as 3.SmJ pulse energy can be obtained under 40-m J, 5-ns pulse pumping. The dependence of output pulse width on the laser crystal's length, pumping pulse duration, and pumping rate is also discussed in detail.

  9. Multi-wavelength erbium-doped fiber laser based on random distributed feedback

    Science.gov (United States)

    Liu, Yuanyang; Dong, Xinyong; Jiang, Meng; Yu, Xia; Shum, Ping

    2016-09-01

    We experimentally demonstrated a multi-wavelength erbium-doped fiber laser based on random distributed feedback via a 20-km-long single-mode fiber together with a Sagnac loop mirror. The number of channels can be modulated from 2 to 8 at room temperature when the pump power is changed from 30 to 180 mW, indicating that wavelength competition caused by homogenous gain broadening of erbium-doped fiber is significantly suppressed. Other advantages of the laser include low cost, low-threshold pump power and simple fabrication.

  10. Multi-wavelength narrow linewidth fiber laser based on distributed feedback fiber lasers

    Science.gov (United States)

    Lv, Jingsheng; Qi, Haifeng; Song, Zhiqiang; Guo, Jian; Ni, Jiasheng; Wang, Chang; Peng, Gangding

    2016-09-01

    A narrow linewidth laser configuration based on distributed feedback fiber lasers (DFB-FL) with eight wavelengths in the international telecommunication union (ITU) grid is presented and realized. In this laser configuration, eight phase-shifted gratings in series are bidirectionally pumped by two 980-nm laser diodes (LDs). The final laser output with over 10-mW power for each wavelength can be obtained, and the maximum power difference within eight wavelengths is 1.2 dB. The laser configuration with multiple wavelengths and uniform power outputs can be very useful in large scaled optical fiber hydrophone fields.

  11. Polymer gratings based on photopolymerization for low-order distributed feedback polymer lasers

    Institute of Scientific and Technical Information of China (English)

    Xuanke Zhao; Qingwu Zhao; Qinghua Zhang

    2008-01-01

    Novel polymer distributed feedback(DFB)gratings are fabricated based on photopolymerization to reduce lasing threshold of polymer lasers.A photopolymer formulation sensitive to 355-nm ultraviolet(UV)light is proposed for the fabrication of polymer gratings and it can be used to form polymer films by spin-coating process.A very low surface-relief depth ranging from 12.5 to about 1.0 nm has been demonstrated with a refractive-index modulation of about 0.012.The experimental results indicate that such polymer gratings have promising potentials for the fabrication of low-order DFB organic semiconductor lasers.

  12. Stock price dynamics and option valuations under volatility feedback effect

    Science.gov (United States)

    Kanniainen, Juho; Piché, Robert

    2013-02-01

    According to the volatility feedback effect, an unexpected increase in squared volatility leads to an immediate decline in the price-dividend ratio. In this paper, we consider the properties of stock price dynamics and option valuations under the volatility feedback effect by modeling the joint dynamics of stock price, dividends, and volatility in continuous time. Most importantly, our model predicts the negative effect of an increase in squared return volatility on the value of deep-in-the-money call options and, furthermore, attempts to explain the volatility puzzle. We theoretically demonstrate a mechanism by which the market price of diffusion return risk, or an equity risk-premium, affects option prices and empirically illustrate how to identify that mechanism using forward-looking information on option contracts. Our theoretical and empirical results support the relevance of the volatility feedback effect. Overall, the results indicate that the prevailing practice of ignoring the time-varying dividend yield in option pricing can lead to oversimplification of the stock market dynamics.

  13. Supervisor Feedback.

    Science.gov (United States)

    Hayman, Marilyn J.

    1981-01-01

    Investigated the effectiveness of supervisor feedback in contributing to learning counseling skills. Counselor trainees (N=64) were assigned to supervisor feedback, no supervisor feedback, or control groups for three training sessions. Results indicated counseling skills were learned best by students with no supervisor feedback but self and peer…

  14. The better, the bigger: The effect of graded positive performance feedback on the reward positivity.

    Science.gov (United States)

    Frömer, Romy; Stürmer, Birgit; Sommer, Werner

    2016-02-01

    In this study on skill acquisition in a computerized throwing task, we examined the effect of graded correct-related performance feedback on the reward positivity of the event-related brain potential (ERP). Theories of reinforcement learning predict effects of reward magnitude and expectancy on the reward prediction error. The later is supposed to be reflected in reward positivity, a fronto-central ERP component. A sample of 68 participants learned to throw at a beamer-projected target disk while performance accuracy, displayed as the place of impact of the projectile on the target, served as graded feedback. Effects of performance accuracy in successful trials, hit frequency, and preceding trial performance on reward positivity were analyzed simultaneously on a trial-by-trial basis by means of linear mixed models. In accord with previous findings, reward positivity increased with feedback about more accurate performance. This relationship was not linear, but cubic, with larger impact of feedback towards the end of the accuracy distribution. In line with being a measure of expectancy, the reward positivity decreased with increasing hit frequency and was larger after unsuccessful trials. The effect of hit frequency was more pronounced following successful trials. These results indicate a fast trial-by-trial adaptation of expectation. The results confirm predictions of reinforcement learning theory and extend previous findings on reward magnitude to the area of complex, goal directed skill acquisition.

  15. A study of spatial phenomena in semiconductor lasers: Beam filamentation and optical feedback effects

    Science.gov (United States)

    Marciante, John Robert

    1997-10-01

    quality of high-power tapered-stripe devices under feedback, paying particular attention to the degradation of the far-field intensity pattern and the issue of filamentation. Finally, we measure the effects of feedback on the spatial distribution of the laser field in broad-area semiconductor lasers, specifically investigating the modification of filamentation due to a lateral displacement in the feedback field with respect to the laser facet.

  16. Output feedback control of heat transport mechanisms in parabolic distributed solar collectors

    KAUST Repository

    Elmetennani, Shahrazed

    2016-08-05

    This paper presents an output feedback control for distributed parabolic solar collectors. The controller aims at forcing the outlet temperature to track a desired reference in order to manage the produced heat despite the external disturbances. The proposed control strategy is derived using the distributed physical model of the system to avoid the loss of information due to model approximation schemes. The system dynamics are driven to follow reference dynamics defined by a transport equation with a constant velocity, which allows to control the transient behavior and the response time of the closed loop. The designed controller depends only on the accessible measured variables which makes it easy for real time implementation and useful for industrial plants. Simulation results show the efficiency of the reference tracking closed loop under different working conditions.

  17. Feedback Channel Suppression in Distributed Video Coding with Adaptive Rate Allocation and Quantization for Multiuser Applications

    Directory of Open Access Journals (Sweden)

    Béatrice Pesquet-Popescu

    2008-12-01

    Full Text Available We present a novel rate allocation technique for distributed multiuser video coding systems without the need for a permanent feedback channel. Based on analytical calculations, the system unequally distributes the available bandwidth among the different users, taking into account the actual amount of movement in the transmitted video as well as the transmission conditions of each user. On one hand, the quantization parameters are dynamically tuned in order to optimize the decoding quality. On the other hand, a frame dropping mechanism allows the system to avoid unnecessary channel use, when the analytical estimations show that the successful decoding of a given frame is not possible because of very high motion or bad channel conditions. A significant gain in the system performance is noticed compared with the case of equal allocation of channel resources and constant quantization parameters.

  18. Laser excitation induced modifications on distributed feedback microcavities using organic semiconductors

    Science.gov (United States)

    Wang, Tingting; Zhang, Xinping

    2017-06-01

    Distributed feedback (DFB) lasers can be achieved by spin-coating semiconductor polymers onto the top surface of a photoresist grating with designed periods. Optical pumping using lasers within the absorption spectrum of the polymer induced strong modification on the morphological distribution of the polymer film and consequently on the spectroscopic response of the DFB microcavities. The corresponding modification processes resulted mainly from the pump-laser-induced cross-linking of the polymer molecules, which led to the reduction in both the thickness and refractive index of the polymer layer. The location of the polymer laser was lowered from the top to the bottom surface of the DFB grating. Concise modeling on the angle-resolved tuning properties of the output spectrum of the DFB microcavity was achieved with excellent agreement with the experimental observation, which provided clear physical insights into the operation mechanisms of a DFB microcavity.

  19. Single-frequency Yb-doped fiber laser with distributed feedback based on a random FBG

    Science.gov (United States)

    Abdullina, S. R.; Vlasov, A. A.; Lobach, I. A.; Belai, O. V.; Shapiro, D. A.; Babin, S. A.

    2016-07-01

    Single-frequency operation of a 1.03 μm fiber laser with random distributed feedback (RDFB) is demonstrated. The laser cavity is based on a 4 cm long fiber Bragg grating (FBG) consisting of 10 homogeneous subgratings with random phase and amplitude of refractive index modulation inscribed in a polarization maintaining (PM) Yb-doped fiber. Such RDFB laser generates single longitudinal mode with output power up to 25 mW, which is 3.5 times higher than that for a DFB laser based on regular π-shifted FBG of the same length in the same fiber. The single-frequency linewidth is measured to be  <100 kHz in both cases. The observed difference of the DFB and RDFB lasers is confirmed by numerical simulation showing different longitudinal distribution of intra-cavity radiation in these cases, analogous to those in the experiment.

  20. Distributed consensus tracking for multiple uncertain nonlinear strict-feedback systems under a directed graph.

    Science.gov (United States)

    Yoo, Sung Jin

    2013-04-01

    In this brief, we study the distributed consensus tracking control problem for multiple strict-feedback systems with unknown nonlinearities under a directed graph topology. It is assumed that the leader's output is time-varying and has been accessed by only a small fraction of followers in a group. The distributed dynamic surface design approach is proposed to design local consensus controllers in order to guarantee the consensus tracking between the followers and the leader. The function approximation technique using neural networks is employed to compensate unknown nonlinear terms induced from the controller design procedure. From the Lyapunov stability theorem, it is shown that the consensus errors are cooperatively semiglobally uniformly ultimately bounded and converge to an adjustable neighborhood of the origin.

  1. Effects of supernova feedback on the formation of galaxy discs

    Science.gov (United States)

    Scannapieco, Cecilia; Tissera, Patricia B.; White, Simon D. M.; Springel, Volker

    2008-09-01

    We use cosmological simulations in order to study the effects of supernova (SN) feedback on the formation of a Milky Way-type galaxy of virial mass ~1012h-1Msolar. We analyse a set of simulations run with the code described by Scannapieco et al., where we have tested our star formation and feedback prescription using isolated galaxy models. Here, we extend this work by simulating the formation of a galaxy in its proper cosmological framework, focusing on the ability of the model to form a disc-like structure in rotational support. We find that SN feedback plays a fundamental role in the evolution of the simulated galaxy, efficiently regulating the star-formation activity, pressurizing the gas and generating mass-loaded galactic winds. These processes affect several galactic properties such as final stellar mass, morphology, angular momentum, chemical properties, and final gas and baryon fractions. In particular, we find that our model is able to reproduce extended disc components with high specific angular momentum and a significant fraction of young stars. The galaxies are also found to have significant spheroids composed almost entirely of stars formed at early times. We find that most combinations of the input parameters yield disc-like components, although with different sizes and thicknesses, indicating that the code can form discs without fine-tuning the implemented physics. We also show how our model scales to smaller systems. By analysing simulations of virial masses 109 and 1010h-1Msolar, we find that the smaller the galaxy, the stronger the SN feedback effects.

  2. Adaptation to delayed auditory feedback induces the temporal recalibration effect in both speech perception and production.

    Science.gov (United States)

    Yamamoto, Kosuke; Kawabata, Hideaki

    2014-12-01

    We ordinarily speak fluently, even though our perceptions of our own voices are disrupted by various environmental acoustic properties. The underlying mechanism of speech is supposed to monitor the temporal relationship between speech production and the perception of auditory feedback, as suggested by a reduction in speech fluency when the speaker is exposed to delayed auditory feedback (DAF). While many studies have reported that DAF influences speech motor processing, its relationship to the temporal tuning effect on multimodal integration, or temporal recalibration, remains unclear. We investigated whether the temporal aspects of both speech perception and production change due to adaptation to the delay between the motor sensation and the auditory feedback. This is a well-used method of inducing temporal recalibration. Participants continually read texts with specific DAF times in order to adapt to the delay. Then, they judged the simultaneity between the motor sensation and the vocal feedback. We measured the rates of speech with which participants read the texts in both the exposure and re-exposure phases. We found that exposure to DAF changed both the rate of speech and the simultaneity judgment, that is, participants' speech gained fluency. Although we also found that a delay of 200 ms appeared to be most effective in decreasing the rates of speech and shifting the distribution on the simultaneity judgment, there was no correlation between these measurements. These findings suggest that both speech motor production and multimodal perception are adaptive to temporal lag but are processed in distinct ways.

  3. Effects of Supernova Feedback on the Formation of Galaxy Disks

    CERN Document Server

    Scannapieco, Cecilia; White, Simon D M; Springel, Volker

    2008-01-01

    We use cosmological simulations in order to study the effects of supernova (SN) feedback on the formation of a Milky Way-type galaxy of virial mass ~10^12 M_sun/h. We analyse a set of simulations run with the code described by Scannapieco et al. (2005, 2006), where we have tested our star formation and feedback prescription using isolated galaxy models. Here we extend this work by simulating the formation of a galaxy in its proper cosmological framework, focusing on the ability of the model to form a disk-like structure in rotational support. We find that SN feedback plays a fundamental role in the evolution of the simulated galaxy, efficiently regulating the star formation activity, pressurizing the gas and generating mass-loaded galactic winds. These processes affect several galactic properties such as final stellar mass, morphology, angular momentum, chemical properties, and final gas and baryon fractions. In particular, we find that our model is able to reproduce extended disk components with high specifi...

  4. Effect of auditory feedback on speech production after cochlear implantation

    Directory of Open Access Journals (Sweden)

    Sheikh Zadeh H

    2001-10-01

    Full Text Available The main goal of this study is to determine the auditory feedback effects in improvement of speech production process in prelingual totally deaf children who used cochlear implant prosthesis. For this reason, we recorded speech of four prelingual cochlear implant children pre and post of operation. Then we extract some static features of vowels-such as fundamental frequency, formant frequencies, vowel duration and vowel energy-from their stable mid-section and analyze them using a longitudinal prosthesis-on/off analysis. These patients-where are in the range of 7-13 years old-were operated in the cochlear implant clinic of Amiralam hospital. At each session, patients read the sentences once in device-on condition and then after 30 minutes stay in device-off condition. Quantitative results show that at least for the features under study, the patient's reliance on the auditory feedback decreased consistently by time (about 65%-averaged on all three vowels under study and all patients. So we concluded that after a sufficient time of operation, the speech motor patterns of patients will be trained for the correct production of static features of vowels and the relation of patients to auditory feedback for the production of such features considerably decreased by time.

  5. Effect of Oral Feedback on Learning Consequences of Nursing Students

    Directory of Open Access Journals (Sweden)

    Monadi Ziyarat H

    2015-06-01

    Full Text Available Aims: Evaluation process is done in form of formative and final assessments. Formative assessment should take place with offering feedback. This study was done with the aim of determining the effect of oral feedback on learning results of nursing students at Abadan Medical Sciences School. Materials & Methods: In this quasi-experimental interfering study, 33 of 5th semester nursing students of Abadan School of Medical Sciences who had passed pediatric training courses during the first semester of 2013-14 academic year were selected by easy and available sampling method (19 people in intervention and 14 people in control group. The data gathering tools were demographic information form, self- done questionnaire in the field of cognitive learning and checklist of learning clinical skills. Every coach was present in both types of training methods. In intervention group, the coach should offer the oral feedback at least one time per day and as closely as possible to student performance. Data was investigated using Chi-square, Mann-Whitney, statistical independent T and paired T tests. Findings: In both groups, the average of learner's scores improve significantly compared to their pre-test in field of cognitive learning (p=0.001. Also, the differential mean of learning scores among the two groups was significant (p=0.001. In the field of clinical skills, there was a significantly difference between the average of scores of intervention and control groups (p=0.001.   Conclusion: Oral feedback can improve cognitive learning and learning clinical skills among nursing students.

  6. The effect of different corrective feedback methods on the outcome and self confidence of young athletes

    National Research Council Canada - National Science Library

    Tzetzis, George; Votsis, Evandros; Kourtessis, Thomas

    2008-01-01

    This experiment investigated the effects of three corrective feedback methods, using different combinations of correction, or error cues and positive feedback for learning two badminton skills with different difficulty...

  7. Comparing the effects of positive and negative feedback in information-integration category learning.

    Science.gov (United States)

    Freedberg, Michael; Glass, Brian; Filoteo, J Vincent; Hazeltine, Eliot; Maddox, W Todd

    2017-01-01

    Categorical learning is dependent on feedback. Here, we compare how positive and negative feedback affect information-integration (II) category learning. Ashby and O'Brien (2007) demonstrated that both positive and negative feedback are required to solve II category problems when feedback was not guaranteed on each trial, and reported no differences between positive-only and negative-only feedback in terms of their effectiveness. We followed up on these findings and conducted 3 experiments in which participants completed 2,400 II categorization trials across three days under 1 of 3 conditions: positive feedback only (PFB), negative feedback only (NFB), or both types of feedback (CP; control partial). An adaptive algorithm controlled the amount of feedback given to each group so that feedback was nearly equated. Using different feedback control procedures, Experiments 1 and 2 demonstrated that participants in the NFB and CP group were able to engage II learning strategies, whereas the PFB group was not. Additionally, the NFB group was able to achieve significantly higher accuracy than the PFB group by Day 3. Experiment 3 revealed that these differences remained even when we equated the information received on feedback trials. Thus, negative feedback appears significantly more effective for learning II category structures. This suggests that the human implicit learning system may be capable of learning in the absence of positive feedback.

  8. Distributed Compressive CSIT Estimation and Feedback for FDD Multi-User Massive MIMO Systems

    Science.gov (United States)

    Rao, Xiongbin; Lau, Vincent K. N.

    2014-06-01

    To fully utilize the spatial multiplexing gains or array gains of massive MIMO, the channel state information must be obtained at the transmitter side (CSIT). However, conventional CSIT estimation approaches are not suitable for FDD massive MIMO systems because of the overwhelming training and feedback overhead. In this paper, we consider multi-user massive MIMO systems and deploy the compressive sensing (CS) technique to reduce the training as well as the feedback overhead in the CSIT estimation. The multi-user massive MIMO systems exhibits a hidden joint sparsity structure in the user channel matrices due to the shared local scatterers in the physical propagation environment. As such, instead of naively applying the conventional CS to the CSIT estimation, we propose a distributed compressive CSIT estimation scheme so that the compressed measurements are observed at the users locally, while the CSIT recovery is performed at the base station jointly. A joint orthogonal matching pursuit recovery algorithm is proposed to perform the CSIT recovery, with the capability of exploiting the hidden joint sparsity in the user channel matrices. We analyze the obtained CSIT quality in terms of the normalized mean absolute error, and through the closed-form expressions, we obtain simple insights into how the joint channel sparsity can be exploited to improve the CSIT recovery performance.

  9. Influence of stack effect on the heat feedback to the n-heptane pool fires

    Science.gov (United States)

    Yuan, Xiangyong; Gao, Zihe; Ji, Jie; Yang, Lizhong; Sun, Jinhua

    2017-05-01

    A set of experiments was conducted in a 1/3 scale building model to study the influence of stack effect on the heat feedback to the n-heptane pool fires. The height of opened window and pool size were varied. Results show that the conduction heat feedback fraction slightly decreases and the radiation heat feedback fraction increases with the increase of the strength of stack effect, while the convection heat feedback fraction remains almost invariant.

  10. Semantic Richness Effects in Syntactic Classification: The Role of Feedback

    Science.gov (United States)

    Yap, Melvin J.; Pexman, Penny M.

    2016-01-01

    Words with richer semantic representations are recognized faster across a range of lexical processing tasks. The most influential account of this finding is based on the idea that semantic richness effects are mediated by feedback from semantic-level to lower-level representations. In an earlier lexical decision study, Yap et al. (2015) tested this claim by examining the joint effects of stimulus quality and four semantic richness dimensions (imageability, number of features, semantic neighborhood density, semantic diversity). The results of that study showed that joint effects of stimulus quality and richness were generally additive, consistent with the idea that semantic feedback does not typically reach the earliest levels of representation in lexical decision. The present study extends this earlier work by investigating the joint effects of stimulus quality and the same four semantic richness dimensions on syntactic classification performance (is this a noun or verb?), which places relatively more emphasis on semantic processing. Additive effects of stimulus quality and richness were found for two of the four targeted dimensions (concreteness, number of features) while semantic neighborhood density and semantic diversity did not seem to influence syntactic classification response times. These findings provide further support against the view that semantic information reaches early letter-level processes. PMID:27695431

  11. Effect of vibrotactile feedback on an EMG-based proportional cursor control system.

    Science.gov (United States)

    Li, Shunchong; Chen, Xingyu; Zhang, Dingguo; Sheng, Xinjun; Zhu, Xiangyang

    2013-01-01

    Surface electromyography (sEMG) has been introduced into the bio-mechatronics systems, however, most of them are lack of the sensory feedback. In this paper, the effect of vibrotactile feedback for a myoelectric cursor control system is investigated quantitatively. Simultaneous and proportional control signals are extracted from EMG using a muscle synergy model. Different types of feedback including vibrotactile feedback and visual feedback are added, assessed and compared with each other. The results show that vibrotactile feedback is capable of improving the performance of EMG-based human machine interface.

  12. Single-frequency thulium-doped distributed-feedback fiber laser.

    Science.gov (United States)

    Agger, Søren; Povlsen, Jørn Hedegaard; Varming, Poul

    2004-07-01

    We have successfully demonstrated a single-frequency distributed-feedback (DFB) thulium-doped silica fiber laser emitting at a wavelength of 1735 nm. The laser cavity is less than 5 cm long and is formed by intracore UV-written Bragg gratings with a phase shift. The laser is pumped at 790 nm from a Ti:sapphire laser and has a threshold pump power of 59 mW. The laser has a maximum output power of 1 mW in a single-frequency, single-polarization radiation mode and is tunable over a few nanometers. To the best of the authors' knowledge, this is the first report of a single-frequency DFB fiber laser that uses thulium as the amplifying medium. The lasing wavelength is the longest demonstrated with DFB fiber lasers and yet is among the shortest obtained for thulium-doped silica fiber lasers.

  13. Single-frequency thulium-doped distributed-feedback fibre laser

    DEFF Research Database (Denmark)

    Agger, Søren; Povlsen, Jørn Hedegaard; Varming, Poul

    2004-01-01

    We have successfully demonstrated a single-frequency distributed-feedback (DFB) thulium-doped silica fiber laser emitting at a wavelength of 1735 nm. The laser cavity is less than 5 cm long and is formed by intracore UV-written Bragg gratings with a phase shift. The laser is pumped at 790 nm from...... that uses thulium as the amplifying medium. The lasing wavelength is the longest demonstrated with DFB fiber lasers and yet is among the shortest obtained for thulium-doped silica fiber lasers....... a Ti:sapphire laser and has a threshold pump power of 59 mW. The laser has a maximum output power of 1 mW in a singlefrequency, single-polarization radiation mode and is tunable over a few nanometers. To the best of the authors’ knowledge, this is the first report of a single-frequency DFB fiber laser...

  14. Evaluation of nanoimprint lithography as a fabrication method of distributed feedback laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Yanagisawa, M; Tsuji, Y; Yoshinaga, H; Hiratsuka, K [Transmission Devices R and D Laboratories, Sumitomo Electric Industries, LTD., 1, Taya-cho, Sakae-ku, Yokohama, 244-8588 Kanagawa (Japan); Taniguchi, J, E-mail: myanagsw@sei.co.j [Faculty of Industrial Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, 278-8510 Chiba (Japan)

    2009-11-15

    We have succeeded in employing nanoimprint lithography (NIL) to form the diffraction gratings of distributed feedback laser diodes (DFB LDs) used in optical communication. Uniform gratings and phase-shifted gratings with periods of 232 nm have been formed by using a reverse NIL with a step-and-repeat imprint tool. Line edge roughness has been sufficiently low with the fabricated gratings. DFB LDs fabricated by NIL have indicated comparable characteristics with LDs fabricated by electron beam lithography. We have also demonstrated that phase-shifted DFB LDs show better uniformity in characteristics than uniform-grating DFB LDs. The results of this study indicate that NIL has high potential for the fabrication of DFB LDs.

  15. A laterally-coupled distributed feedback laser with equivalent quarter-wave phase shift.

    Science.gov (United States)

    Li, Jingsi; Cheng, Julian

    2013-11-04

    We report the first laterally-coupled distributed feedback (LC-DFB) laser with a quarter-wave equivalent phase shift (EPS) realized by interference lithography (IL) and conventional photolithography. A specially designed sampled grating is fabricated on both sidewalls of a ridge waveguide to provide a quarter-wave EPS at the center of the cavity. The resulting laser exhibits stable single-mode lasing operation over a wide range of injection currents, with a side mode suppression ratio (SMSR) of 41.1 dB. This provides a practical, low-cost method to fabricate quarter-wave phase shifted DFB lasers with high performance without any epitaxial regrowth or the use of electron-beam lithography, thereby simplifying the fabrication of DFB lasers with stable and precise wavelengths, as single devices or as arrays in photonic integrated circuits.

  16. Temporal output profile of gain-coupled distributed feedback dye laser

    Science.gov (United States)

    Pasandideh, K.; Souri, S.; Gohari Kamel, N.; Sadighi-Bonabi, R.

    2017-08-01

    The lasing mechanism and temporal output profile of distributed feedback dye lasers is investigated, using a model based on induced polarization in the dye solution, where a more accurate behavior of the laser output is predicted. It is found that the temporal output profile of the laser is mostly determined by the concentration of dye solution and the lifetime of the upper laser level of dye molecules. To a large extent, the results of this work agree with experimental studies, even at high-level pump intensities where the self Q-switched model fails to be applied. Especially, the experimentally observed irregular intensity profile of laser output is explained. It is also shown that, when pumping dye solution by narrower pulses, the single-pulse output mode can be realized in the wider range of pump intensities and the pulsewidth stability of laser can be improved.

  17. Surface Emitting Distributed Feedback Quantum Cascade Laser around 8.3μm

    Institute of Scientific and Technical Information of China (English)

    GUO Wan-Hong; LIU Jun-Qi; LU Quan-Yong; ZHANG Wei; JIANG Yu-Chao; LI Lu; WANG Li-Jun; LIU Feng-Qi; WANG Zhan-Guo

    2010-01-01

    @@ We demonstrate surface emitting distributed feedback quantum cascade lasers emitting at wavelengths from8.1 μm at 90 K to 8.4 μm at 210K.The second-order metalized grating is carefully designed using a modified coupled-mode theory and fabricated by contact lithography.The devices show single mode behavior with a side mode suppression ratio above 18dB at all working temperatures.At 90K,the device emits an optical power of 101 mW from the surface and 199mW from the edge.In addition,a double-lobe far-field pattern with a separation of 2.2° is obtained in the direction along the waveguide.

  18. Study on stimulated emission from polymer distributed feedback waveguide using interference ablation

    Science.gov (United States)

    Zhang, Bo; Cheng, Hao; Sun, Yangyang

    2014-11-01

    A polymer distributed feedback (DFB) laser was fabricated by two-beam interference from MEH-PPV film on clear glass substrate. A direct-writing technique was reported that achieves large-area 1D DFB polymer lasers. The polymer thin film was exposed to a single-shot illumination of the interference pattern of one UV laser pulse at 355 nm. The direct-writing and the lasing characters of 1D DFB polymer lasers were demonstrated. The results show the lower threshold and full width at half maximum (FWHM) from DFB polymer laser than slab waveguide. The peak position is tuned by changing the period from 340 nm to 350 nm. The results show that the simple and low-cost technique that enables highly reproducible mass fabrication is required for the easy realization and more profound investigation of the polymer lasers based on the DFB configuration.

  19. Inversionless gain via six-wave mixing and the investigation of distributed feedback

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hong [College of Physics and Electronic Engineering, Hainan Normal University, Haikou, 571158 (China); Zhang, Ting-Gui [School of Mathematics and Statistics, Hainan Normal University, Haikou, 571158 (China); Zou, Xu [College of Physics and Electronic Engineering, Hainan Normal University, Haikou, 571158 (China); Zhang, Yan, E-mail: zhangy345@nenu.edu.cn [School of Physics and Center for Quantum Sciences, Northeast Normal University, Changchun 130024 (China)

    2017-05-10

    In the present paper, we investigate the spectral-line enhancement of a coherently driven treble-Λ type atomic system. The numerical results show that the amplitudes and the amplification region of probe fields can be all-optically manipulated by modulating the detunings and intensities of coupling fields. In this case, we trap the cold atoms of treble-Λ type in a one-dimensional optical lattice to study the intensity envelopes by the modulation of gain or simultaneous modulation of gain and index. - Highlights: • There are three advantages in this model. • Firstly, it can simultaneously control the three-color probe fields. • Secondly, it allows synchronous nonlinear manipulation of treble-light signals at one network node. • Thirdly, it can be realized distributed feedback lasers.

  20. Physically transient photonics: random versus distributed feedback lasing based on nanoimprinted DNA.

    Science.gov (United States)

    Camposeo, Andrea; Del Carro, Pompilio; Persano, Luana; Cyprych, Konrad; Szukalski, Adam; Sznitko, Lech; Mysliwiec, Jaroslaw; Pisignano, Dario

    2014-10-28

    Room-temperature nanoimprinted, DNA-based distributed feedback (DFB) laser operation at 605 nm is reported. The laser is made of a pure DNA host matrix doped with gain dyes. At high excitation densities, the emission of the untextured dye-doped DNA films is characterized by a broad emission peak with an overall line width of 12 nm and superimposed narrow peaks, characteristic of random lasing. Moreover, direct patterning of the DNA films is demonstrated with a resolution down to 100 nm, enabling the realization of both surface-emitting and edge-emitting DFB lasers with a typical line width of <0.3 nm. The resulting emission is polarized, with a ratio between the TE- and TM-polarized intensities exceeding 30. In addition, the nanopatterned devices dissolve in water within less than 2 min. These results demonstrate the possibility of realizing various physically transient nanophotonics and laser architectures, including random lasing and nanoimprinted devices, based on natural biopolymers.

  1. Distributed output-feedback formation tracking control for unmanned aerial vehicles

    Science.gov (United States)

    He, Lei; Sun, Xiuxia; Lin, Yan

    2016-12-01

    This paper considers the output-feedback formation problem of tracking a desired trajectory for a group of networked unmanned aerial vehicles (UAVs). By introducing a state observer, the controller for the non-holonomic UAV model can be designed without linear and angular velocities measurements. The formation robustness can be improved by applying the virtual structure and synchronising the path parameters. It is proved that, with the proposed control strategy, all the closed-loop signals are bounded and the formation tracking errors asymptotically converge to zero. Simulation results are given to illustrate the effectiveness of the proposed control strategy.

  2. Feedback from Outcome Measures and Treatment Effectiveness, Treatment Efficiency, and Collaborative Practice: A Systematic Review.

    Science.gov (United States)

    Gondek, Dawid; Edbrooke-Childs, Julian; Fink, Elian; Deighton, Jessica; Wolpert, Miranda

    2016-05-01

    Due to recent increases in the use of feedback from outcome measures in mental health settings, we systematically reviewed evidence regarding the impact of feedback from outcome measures on treatment effectiveness, treatment efficiency, and collaborative practice. In over half of 32 studies reviewed, the feedback condition had significantly higher levels of treatment effectiveness on at least one treatment outcome variable. Feedback was particularly effective for not-on-track patients or when it was provided to both clinicians and patients. The findings for treatment efficiency and collaborative practice were less consistent. Given the heterogeneity of studies, more research is needed to determine when and for whom feedback is most effective.

  3. Regimes of Generation in Low-Q Distributed-Feedback Lasers with Strong Inhomogeneous Broadening of the Active Medium

    Science.gov (United States)

    Kocharovskaya, E. R.; Ginzburg, N. S.; Sergeev, A. S.; Kocharovsky, V. V.; Kocharovsky, Vl. V.

    2016-11-01

    We study the influence of the ratio between the relaxation rates of the field in a cavity and the polarization of active centers on the dynamic properties of the distributed-feedback lasers by means of 1D numerical simulation. The model of a two-level active medium with strong inhomogeneous broadening of the spectral line under CW wide-band pumping that provides two- or several-mode lasing in the vicinity of the Bragg photonic band gap is used. Evolution of the dynamic spectra and oscillograms of the laser emission with decreasing Q-factor of the Bragg resonator is analyzed. It is shown, in particular, that under conditions of the dominant role of the superradiant effects, there are unique opportunities for control of both quantitative and qualitative characteristics of lasing, including the spectral width, duration, and coherence length of various pulse components of the output radiation.

  4. Coupling coefficient calculation for GaSb-based quantum well distributed feedback lasers with laterally coupled gratings

    Science.gov (United States)

    Wang, Y. B.; Xu, Y.; Zhang, Y.; Song, G. F.; Chen, L. H.

    2012-12-01

    We calculated the coupling coefficient of different types of laterally coupled distributed feedback (LC-DFB) structures with coupled-wave theory and the two-dimensional semivectorial finite difference method. Effects neglected in previous studies such as other partial waves, the ohmic contact and metal contact layers are taken into account in this calculation. The LC-DFB structure with metal gratings is especially studied due to its advantage over index-coupled structures. The dependence of coupling coefficient on structure parameters is theoretically calculated such as grating order, ridge width, thickness of the residual cladding layer, grating depth and lateral proximity of gratings to the ridge waveguide. A complex-coupled GaSb-based 2 µm LC-DFB structure is optimized to achieve a high coupling coefficient of 14.5 cm-1.

  5. Normative Feedback Effects on Learning a Timing Task

    Science.gov (United States)

    Wulf, Gabriele; Chiviacowsky, Suzete; Lewthwaite, Rebecca

    2010-01-01

    This study investigated the influence of normative feedback on learning a sequential timing task. In addition to feedback about their performance per trial, two groups of participants received bogus normative feedback about a peer group's average block-to-block improvement after each block of 10 trials. Scores indicated either greater (better…

  6. Problems Associated with Implementation of an Effective Upward Appraisal Feedback Process: An Experimental Field Study.

    Science.gov (United States)

    Antonioni, David

    1995-01-01

    Investigated the effects of written-upward appraisal reports (feedback) and performance reviews on the supervisory behavior of 96 managers. Results indicate that managers who received feedback did not improve their supervision more than managers who did not receive feedback. Discusses problems and provides recommendations for the design of an…

  7. The Effect of Emotional Feedback on Behavioral Intention to Use Computer Based Assessment

    Science.gov (United States)

    Terzis, Vasileios; Moridis, Christos N.; Economides, Anastasios A.

    2012-01-01

    This study introduces emotional feedback as a construct in an acceptance model. It explores the effect of emotional feedback on behavioral intention to use Computer Based Assessment (CBA). A female Embodied Conversational Agent (ECA) with empathetic encouragement behavior was displayed as emotional feedback. More specifically, this research aims…

  8. The Value and Effectiveness of Feedback in Improving Students' Learning and Professionalizing Teaching in Higher Education

    Science.gov (United States)

    Ahea, Md. Mamoon-Al-Bashir; Ahea, Md. Rezaul Kabir; Rahman, Ismat

    2016-01-01

    There is a great importance of feedback in improving learning experience for the students. This has also significant effect in professionalizing teaching in the higher education level. However, feedback is considered as a difficult issue in this arena. Most of the lecturers are still continuing with the tradition form of feedback. This form of…

  9. When Feedback Harms and Collaboration Helps in Computer Simulation Environments: An Expertise Reversal Effect

    Science.gov (United States)

    Nihalani, Priya K.; Mayrath, Michael; Robinson, Daniel H.

    2011-01-01

    We investigated the effects of feedback and collaboration on undergraduates' transfer performance when using a computer networking training simulation. In Experiment 1, 65 computer science "novices" worked through an instructional protocol individually (control), individually with feedback, or collaboratively with feedback. Unexpectedly,…

  10. The Effect of Direct and Indirect Corrective Feedback on Iranian EFL Learners' Spelling Errors

    Science.gov (United States)

    Ghandi, Maryam; Maghsoudi, Mojtaba

    2014-01-01

    The aim of the current study was to investigate the impact of indirect corrective feedback on promoting Iranian high school students' spelling accuracy in English (as a foreign language). It compared the effect of direct feedback with indirect feedback on students' written work dictated by their teacher from Chicken Soup for the Mother and…

  11. Effects of longitudinal small-group learning on delivery and receipt of communication skills feedback.

    Science.gov (United States)

    Chou, Calvin L; Masters, Dylan E; Chang, Anna; Kruidering, Marieke; Hauer, Karen E

    2013-11-01

    Although feedback is a critical component of learning, recent data suggest that learners may discount feedback they receive. The emotional threat inherent in feedback can contribute to its ineffectiveness, particularly for sensitive topics like communication skills. Longitudinal relationships among peers may increase their sense of safety and soften the perceived threat of feedback to allow students to give, receive and potentially more effectively incorporate feedback. We studied the effects of prior shared learning experiences among medical students in the delivery and receipt of feedback on clinical (communication) skills. During a formative clinical skills examination, we divided Year 3 students at a US medical school into two subgroups comprising, respectively, small-group classmates from a 2-year longitudinal pre-clerkship clinical skills course (with prior peer-learning relationships), and peers with no prior shared small-group coursework. Students in both subgroups observed peers in a simulated clinical case and then provided feedback, which was videotaped, transcribed and coded. Feedback recipients also completed a survey on their perceptions of the feedback. Students valued the feedback they received and intended to enact it, regardless of whether they had prior peer-learning relationships. Coding of feedback revealed high specificity. Feedback providers who had prior peer-learning relationships with recipients provided more specific corrective feedback on communication skills than those with no such relationships (p = 0.014); there was no significant difference between subgroups in the provision of reinforcing feedback on communication skills. Year 3 medical student peers can deliver specific feedback on clinical skills; prior peer-learning relationships in pre-clerkship clinical skills courses enrich the provision of specific corrective feedback about communication skills. Feedback between peers with pre-existing peer-learning relationships represents

  12. Effects of diaphragm breathing exercise and feedback breathing exercise on pulmonary function in healthy adults

    OpenAIRE

    Yong, Min-Sik; Lee, Hae-Yong; Lee, Yun-Seob

    2017-01-01

    [Purpose] The present study investigated effects of diaphragm breathing exercise and feedback breathing exercise on respiratory function. [Subjects and Methods] Thirty-one subjects were randomly assigned to two groups; the feedback breathing exercise group and the maneuver-diaphragm exercise group. The feedback breathing exercise group was asked to breathe with feedback breathing device, and the maneuver-diaphragm exercise group was asked to perform diaphragm respiration. Respiratory function...

  13. The effect of direct and indirect corrective feedback on students’ spelling errors

    OpenAIRE

    Baleghizadeh Sasan; Dadashi Mehdi

    2011-01-01

    The study presented here is an attempt to examine the role of indirect feedback in promoting junior high school students’ spelling accuracy in English. It compares the effect of direct feedback with indirect feedback on students’ written work dictated by their teacher from their textbooks. Two classes were selected from the Zanjanrood District in Iran. Forty-four male students in two groups, one from School A (the direct feedback group) and the other from School B (the indirect feedb...

  14. An Exploratory Study of "Quantitative Linguistic Feedback": Effect of LENA Feedback on Adult Language Production

    Science.gov (United States)

    Suskind, Dana; Leffel, Kristin R.; Hernandez, Marc W.; Sapolich, Shannon G.; Suskind, Elizabeth; Kirkham, Erin; Meehan, Patrick

    2013-01-01

    A child's early language environment is critical to his or her life-course trajectory. Quantitative linguistic feedback utilizes the Language ENvironment Analysis (LENA) technology as a tool to analyze verbal interactions and reinforce behavior change. This exploratory pilot study evaluates the feasibility and efficacy of a novel behavior-change…

  15. Flat acoustic sources with frequency response correction based on feedback and feed-forward distributed control.

    Science.gov (United States)

    Ho, Jen-Hsuan; Berkhoff, Arthur P

    2015-04-01

    This paper presents an acoustic source with a small thickness and high bending stiffness. The high bending stiffness is obtained with a sandwich structure in which the face of the sandwich structure internal to the source is perforated to increase the acoustic compliance, thereby leading to increased electroacoustic conversion efficiency. Multiple actuators are used to drive the moving component of the acoustic source. Control of the acoustic resonances and structural resonances is required to obtain an even frequency response. The use of collocated decentralized feedback control based on velocity sensing was found to be ineffective for controlling these resonances due to the destabilizing asymmetric modes caused by the coupling of the internal acoustic cavity and the rigid body vibration of the moving component. Resonances can be controlled by a set of independent combinations of symmetric driving patterns with corresponding velocity feedback controllers such that the fundamental mass-air resonance is effectively controlled, as is the lowest bending mode of the moving component. Finally, a compensation scheme for low frequencies is used which enables a flat frequency response in the range of 30 Hz to 1 kHz with deviations smaller than 3 dB.

  16. The effect of performance feedback on cardiorespiratory fitness field tests.

    Science.gov (United States)

    Metsios, G S; Flouris, A D; Koutedakis, Y; Theodorakis, Y

    2006-06-01

    We investigated the effects of performance feedback (PF) on predicting maximal oxygen uptake (VO2 max) using the 20 m Multistage Shuttle Run Test (MST) and 20 m Square Shuttle Test (SST). The agreement between these two field tests in relation to laboratory VO2 max was also examined. Forty healthy males (age: 21.5+/-2.3; BMI: 23.7+/-2.0) randomly performed four indirect VO2 max tests; that is the MST and SST, as well as a modified version of MST (MSTMD) and SST (SSTMD). During MST and SST subjects received PF with respect to both test stage and running pace. In contrast, MSTMD and SSTMD incorporated auditory feedback which solely emitted signals regulating the running pace. Participants also performed a laboratory VO2 max treadmill test (TT). ANOVA demonstrated significant mean predicted VO2 max decrements in both MSTMD (pmax, the '95% limits of agreement' analysis indicated errors equal to 3.6+/-9.6 and 1.4+/-10.3 ml kg-1 min-1 with coefficients of variation of +/-10.0% and +/-10.9%, for MST and MSTMD, respectively. The corresponding '95% limits of agreement' values for SST and SSTMD were 0.1+/-5.0 and -1.1+/-6.1 ml kg-1 min-1 with coefficients of variation of +/-5.4% and +/-6.7%, respectively. It is concluded that the application of PF leads to superior field testing performances.

  17. Stable microwave generation in a dual-phase-shifted Al2O3:Yb3+ distributed-feedback waveguide laser

    NARCIS (Netherlands)

    Bernhardi, Edward; van Wolferen, Hendricus A.G.M.; Worhoff, Kerstin; de Ridder, R.M.; Pollnau, Markus

    A dual-wavelength distributed-feedback channel waveguide laser in ytterbium-doped aluminum oxide was used to create a microwave beat signal at ~15 GHz, with a frequency stability of ±2.5 MHz and a power stability of ±0.35 dB.

  18. Distributed feedback channel waveguide lasers in erbium- and ytterbium-doped Al2O3:Er3+ on silicon

    NARCIS (Netherlands)

    Bernhardi, Edward; van Wolferen, Hendricus A.G.M.; Worhoff, Kerstin; de Ridder, R.M.; Pollnau, Markus

    We present the fabrication and performance of distributed feedback channel waveguide lasers in erbium- and ytterbium-doped aluminium oxide. The low-threshold devices demonstrate slope efficiencies up to 67% and narrow linewidths as low as 1.7 kHz.

  19. Business Activity Monitoring: Real-Time Group Goals and Feedback Using an Overhead Scoreboard in a Distribution Center

    Science.gov (United States)

    Goomas, David T.; Smith, Stuart M.; Ludwig, Timothy D.

    2011-01-01

    Companies operating large industrial settings often find delivering timely and accurate feedback to employees to be one of the toughest challenges they face in implementing performance management programs. In this report, an overhead scoreboard at a retailer's distribution center informed teams of order selectors as to how many tasks were…

  20. Stable microwave generation in a dual-phase-shifted $Al_2O_3:Yb^{3+}$ distributed-feedback waveguide laser

    NARCIS (Netherlands)

    Bernhardi, E.H.; Wolferen, van H.A.G.M.; Wörhoff, K.; Ridder, de R.M.; Pollnau, M.

    2012-01-01

    A dual-wavelength distributed-feedback channel waveguide laser in ytterbium-doped aluminum oxide was used to create a microwave beat signal at ~15 GHz, with a frequency stability of ±2.5 MHz and a power stability of ±0.35 dB.

  1. Effects of generic versus non-generic feedback on motor learning in children.

    Directory of Open Access Journals (Sweden)

    Suzete Chiviacowsky

    Full Text Available Non-generic feedback refers to a specific event and implies that performance is malleable, while generic feedback implies that task performance reflects an inherent ability. The present study examined the influences of generic versus non-generic feedback on motor performance and learning in 10-year-old children. In the first experiment, using soccer ball kicking at a target as a task, providing participants with generic feedback resulted in worse performance than providing non-generic feedback, after both groups received negative feedback. The second experiment measured more permanent effects. Results of a retention test, performed one day after practicing a throwing task, showed that participants who received non-generic feedback during practice outperformed the generic feedback group, after receiving a negative feedback statement. The findings demonstrate the importance of the wording of feedback. Even though different positive feedback statements may not have an immediate influence on performance, they can affect performance, and presumably individuals' motivation, when performance is (purportedly poor. Feedback implying that performance is malleable, rather than due to an inherent ability, seems to have the potential to inoculate learners against setbacks--a situation frequently encountered in the context of motor performance and learning.

  2. The effect of stellar and AGN feedback on the low-redshift Lyman α forest in the Sherwood simulation suite

    Science.gov (United States)

    Nasir, Fahad; Bolton, James S.; Viel, Matteo; Kim, Tae-Sun; Haehnelt, Martin G.; Puchwein, Ewald; Sijacki, Debora

    2017-10-01

    We study the effect of different feedback prescriptions on the properties of the low-redshift (z ≤ 1.6) Lyα forest using a selection of hydrodynamical simulations drawn from the Sherwood simulation suite. The simulations incorporate stellar feedback, active galactic nuclei (AGN) feedback and a simplified scheme for efficiently modelling the low column density Lyα forest. We confirm a discrepancy remains between Cosmic Origins Spectrograph (COS) observations of the Lyα forest column density distribution function (CDDF) at z ≃ 0.1 for high column density systems (N_{H I}>10^{14} cm^{-2}), as well as Lyα velocity widths that are too narrow compared to the COS data. Stellar or AGN feedback - as currently implemented in our simulations - has only a small effect on the CDDF and velocity width distribution. We conclude that resolving the discrepancy between the COS data and simulations requires an increase in the temperature of overdense gas with Δ = 4-40, either through additional He II photoheating at z > 2 or fine-tuned feedback that ejects overdense gas into the intergalactic medium at just the right temperature for it to still contribute significantly to the Lyα forest. Alternatively a larger, currently unresolved turbulent component to the line width could resolve the discrepancy.

  3. Highly stable solution processed metal-halide perovskite lasers on nanoimprinted distributed feedback structures

    Science.gov (United States)

    Brenner, Philipp; Stulz, Mareike; Kapp, Dorothee; Abzieher, Tobias; Paetzold, Ulrich W.; Quintilla, Aina; Howard, Ian A.; Kalt, Heinz; Lemmer, Uli

    2016-10-01

    We report on the performance and stability of distributed feedback lasers based on the solution-processed methylammonium lead iodide perovskite (CH3NH3PbI3). The CH3NH3PbI3 layers are processed via solution-casting in ambient atmosphere onto nanoimprinted second order Bragg gratings. This way, we achieve highly polarized surface-emitted lasing at room temperature with a linewidth of less than 0.2 nm and a laser threshold of 120 kW/cm2. The lasing is stable; no change in the laser emission within 15 h of pulsed excitation with a repetition rate of 1 kHz (corresponding to >5 × 107 pulses) is observed, exceeding the stability achieved for solution processed organic semiconductor lasers. Furthermore, adjustment of the grating period allowed the lasing wavelength to be varied over the entire bandwidth of the amplified spontaneous emission (between 781 and 794 nm). The fabrication process of nanoimprinting followed by solution-casting of the gain material demonstrates that stable CH3NH3PbI3 lasers are compatible with scalable production technologies and offers a route towards electrically pumped diode architectures.

  4. Distributed Cooperative Current-Sharing Control of Parallel Chargers Using Feedback Linearization

    Directory of Open Access Journals (Sweden)

    Jiangang Liu

    2014-01-01

    Full Text Available We propose a distributed current-sharing scheme to address the output current imbalance problem for the parallel chargers in the energy storage type light rail vehicle system. By treating the parallel chargers as a group of agents with output information sharing through communication network, the current-sharing control problem is recast as the consensus tracking problem of multiagents. To facilitate the design, input-output feedback linearization is first applied to transform the nonidentical nonlinear charging system model into the first-order integrator. Then, a general saturation function is introduced to design the cooperative current-sharing control law which can guarantee the boundedness of the proposed control. The cooperative stability of the closed-loop system under fixed and dynamic communication topologies is rigorously proved with the aid of Lyapunov function and LaSalle invariant principle. Simulation using a multicharging test system further illustrates that the output currents of parallel chargers are balanced using the proposed control.

  5. A high-order external distributed feedback polymer laser with low working threshold

    Science.gov (United States)

    Huang, Wenbin; Pu, Donglin; Yang, Xiaofei; Wei, Guojun; Fang, Zongbao; Zhou, Xiaohong; Qiao, Wen; Chen, Linsen

    2016-05-01

    In this paper, we report a high-order distributed feedback (DFB) polymer laser with low working threshold. Using the high-order grating increases the lithographic tolerances, providing coherent light sources that are more amenable to mass-manufacturing techniques, such as laser direct writing lithography and roll-to-roll processing. To enable high-order DFB lasing, an unconventional working configuration is designed in which the grating is situated on top of the uniform conjugated polymer film. In addition, a novel Forster energy transfer blend of two conjugated polymers is used as the gain medium. Upon pumping, the device emits lasing around 603.6 nm with a bandwidth of 0.5 nm. The threshold is around 20.5 μJ cm-2 (~2.56 kW cm-2), about to enter the regime of inexpensive LED pumping. A further increase in pump energy results in simultaneous oscillations at the 29th and 30th Bragg orders. Operating principles of the high-order DFB polymer laser, including spectral performance and threshold dependence on pump length, are investigated. This approach represents a step towards low-cost, even ‘disposable’ polymer lasers.

  6. Feedback optimal control of distributed parameter systems by using finite-dimensional approximation schemes.

    Science.gov (United States)

    Alessandri, Angelo; Gaggero, Mauro; Zoppoli, Riccardo

    2012-06-01

    Optimal control for systems described by partial differential equations is investigated by proposing a methodology to design feedback controllers in approximate form. The approximation stems from constraining the control law to take on a fixed structure, where a finite number of free parameters can be suitably chosen. The original infinite-dimensional optimization problem is then reduced to a mathematical programming one of finite dimension that consists in optimizing the parameters. The solution of such a problem is performed by using sequential quadratic programming. Linear combinations of fixed and parameterized basis functions are used as the structure for the control law, thus giving rise to two different finite-dimensional approximation schemes. The proposed paradigm is general since it allows one to treat problems with distributed and boundary controls within the same approximation framework. It can be applied to systems described by either linear or nonlinear elliptic, parabolic, and hyperbolic equations in arbitrary multidimensional domains. Simulation results obtained in two case studies show the potentials of the proposed approach as compared with dynamic programming.

  7. A GaAs-based self-aligned stripe distributed feedback laser

    Science.gov (United States)

    Lei, H.; Stevens, B. J.; Fry, P. W.; Babazadeh, N.; Ternent, G.; Childs, D. T.; Groom, K. M.

    2016-08-01

    We demonstrate operation of a GaAs-based self-aligned stripe (SAS) distributed feedback (DFB) laser. In this structure, a first order GaInP/GaAs index-coupled DFB grating is built within the p-doped AlGaAs layer between the active region and the n-doped GaInP opto-electronic confinement layer of a SAS laser structure. In this process no Al-containing layers are exposed to atmosphere prior to overgrowth. The use of AlGaAs cladding affords the luxury of full flexibility in upper cladding design, which proved necessary due to limitations imposed by the grating infill and overgrowth with the GaInP current block layer. Resultant devices exhibit single-mode lasing with high side-mode-suppression of >40 dB over the temperature range 20 °C-70 °C. The experimentally determined optical profile and grating confinement correlate well with those simulated using Fimmwave.

  8. Fast BPM data distribution for global orbit feedback using commercial gigabit ethernet technology

    Energy Technology Data Exchange (ETDEWEB)

    Hulsart, R.; Cerniglia, P.; Michnoff, R.; Minty, M.

    2011-03-28

    In order to correct beam perturbations in RHIC around 10Hz, a new fast data distribution network was required to deliver BPM position data at rates several orders of magnitude above the capability of the existing system. The urgency of the project limited the amount of custom hardware that could be developed, which dictated the use of as much commercially available equipment as possible. The selected architecture uses a custom hardware interface to the existing RHIC BPM electronics together with commercially available Gigabit Ethernet switches to distribute position data to devices located around the collider ring. Using the minimum Ethernet packet size and a field programmable gate array (FPGA) based state machine logic instead of a software based driver, real-time and deterministic data delivery is possible using Ethernet. The method of adapting this protocol for low latency data delivery, bench testing of Ethernet hardware, and the logic to construct Ethernet packets using FPGA hardware will be discussed. A robust communications system using almost all commercial off-the-shelf equipment was developed in under a year which enabled retrofitting of the existing RHIC BPM system to provide 10 KHz data delivery for a global orbit feedback scheme using 72 BPMs. Total latencies from data acquisition at the BPMs to delivery at the controller modules, including very long transmission distances, were kept under 100 {micro}s, which provide very little phase error in correcting the 10 Hz oscillations. Leveraging off of the speed of Gigabit Ethernet and wide availability of Ethernet products enabled this solution to be fully implemented in a much shorter time and at lower cost than if a similar network was developed using a proprietary method.

  9. Arbitrarily low sensitivity (ALS) in linear distributed systems using pointwise linear feedback

    NARCIS (Netherlands)

    Kelemen, Matei; Kennai, Yakar; Horowitz, Isaac

    1990-01-01

    The sensitivity problem is defined for feedback systems with plants described by linear partial differential operators having constant coefficients, in a bounded one-dimensional domain. there are also finitely many observation points and finitely many lumped feedback loops, and a finite number of di

  10. Arbitrarily low sensitivity (ALS) in linear distributed systems using pointwise linear feedback

    NARCIS (Netherlands)

    Kelemen, Matei; Kennai, Yakar; Horowitz, Isaac

    1990-01-01

    The sensitivity problem is defined for feedback systems with plants described by linear partial differential operators having constant coefficients, in a bounded one-dimensional domain. there are also finitely many observation points and finitely many lumped feedback loops, and a finite number of

  11. Tropical cirrus and water vapor: an effective Earth infrared iris feedback?

    Directory of Open Access Journals (Sweden)

    Q. Fu

    2001-09-01

    Full Text Available We revisit a model of feedback processes proposed by Lindzen et al. (2001, in which an assumed 22% reduction in the area of tropical high clouds per degree of sea surface temperature increase produces negative feedbacks associated with upper tropospheric water vapor and cloud radiative effects. We argue that the water vapor feedback is overestimated in Lindzen et al. (2001 by at least 60%, and that the high cloud feedback should be small. Although not mentioned by Lindzen et al, tropical low clouds make a significant contribution to their negative feedback, which is also overestimated. Using more realistic parameters in the model of Lindzen et al., we obtain a feedback factor in the range of −0.15 to −0.51, compared to their larger negative feedback factor of −0.45 to −1.03.

  12. The Effect of Two Types of Feedback on Iranian EFL Learners' Tense-marker Production

    Directory of Open Access Journals (Sweden)

    Somayeh Kazemi Tari

    2011-01-01

    Full Text Available Although many researchers have worked on the role of feedback in immersion programs on second language learners' production, still little is known about the role of different types of immediate feedback on the grammatical accuracy of learners' production. When, where and with who different types of immediate feedback such as prompts and recasts and their different subcategories might be appropriate? The purpose of the present research was to know which types of immediate oral feedback could better help Iranian EFL learners to produce the correct form of the tense markers of their target language English. One of the primary objectives of the present study was to examine the effects of two types of oral feedback namely explicit correction and implicit or-choice feedback on Iranian EFL learners' production of different tense markers in English. The results were in favor of explicit correction over implicit or-choice feedback in helping learners to produce correct grammatical tense markers.

  13. Cloud Susceptibilities to Ice Nuclei: Microphysical Effects and Dynamical Feedbacks

    Science.gov (United States)

    Paukert, Marco; Hoose, Corinna

    2015-04-01

    The impact of aerosols on cloud properties is currently not well established. This is largely attributed to the interdependencies of aerosols and cloud microphysical processes, among which primary ice formation contributes to considerable uncertainties. Although it is known that in a large range of thermodynamic conditions aerosol particles are required to initiate ice formation, identifying and characterizing the effect of specific ice nuclei is among current scientific efforts. Here we attempt to quantify the change of cloud properties with varying aerosol background concentrations. We adapt the concept of susceptibilities for mixed-phase and ice clouds, defining the susceptibility as the derivation of a macrophysical quantity with respect to ice nucleating aerosol concentrations. A focus of our study is the use of different model approaches in order to identify the distinct contributions of both cloud microphysics and cloud-dynamical feedbacks to the overall susceptibility. The classical method is the direct comparison of two independent model runs, where the whole range of microphysical and cloud-dynamical feedbacks contributes to different cloud properties in a perturbed simulation. Our alternative method relies on a single simulation which incorporates multiple executions of the microphysical scheme within the same time step, each "perturbed microphysics" scheme with varying aerosol concentrations and an additional set of cloud particle tracers. Since in the latter case the model dynamics are held constant and only microphysical feedbacks contribute to the properties of perturbed clouds, we can distinguish between the pure microphysical effect and the dynamical enhancement or suppression. For a persistent Arctic mixed-phase stratocumulus cloud layer which is expected to be particularly sensitive to feedback cycles, we show an enhancement of the cloud susceptibility to ice nucleating particles by dynamics of around 50%, but a decay of the enhancement with time

  14. Effects of Verbal and Graphed Feedback on Treatment Integrity

    Science.gov (United States)

    Zoder-Martell, Kimberly; Dufrene, Brad; Sterling, Heather; Tingstrom, Daniel; Blaze, John; Duncan, Neelima; Harpole, Lauren

    2013-01-01

    Treatment integrity is the degree to which an intervention is implemented as designed and is critical for concluding whether the intervention is responsible for treatment outcomes. This study aimed to add to the integrity literature by examining graphed performance feedback alone and in conjunction with verbal performance feedback for increasing…

  15. The IMF of stellar clusters: effects of accretion and feedback

    CERN Document Server

    Dib, Sami; Padoan, Paolo; G., Maheswar; Ojha, D K; Khajenabi, Fazeleh

    2009-01-01

    (abridged) We develop a model which describes the coevolution of the mass function of dense cores and of the IMF in a protocluster clump. In the model, cores injected in the clump evolve under the effect of gas accretion. Accretion onto the cores follows a time-dependent accretion rate that describes accretion in a turbulent medium. Once the accretion timescales of cores exceed their contraction timescales, they are turned into stars. We include the effect of feedback by the newly formed massive stars through their stellar winds. A fraction of the wind's energy is assumed to counter gravity and disperse the gas from the protocluster and as a consequence, quench further star formation. The latter effect sets the final IMF of the cluster. We apply our model to a clump that is expected to resemble the progenitor clump of the Orion Nebula Cluster (ONC). Our model is able to reproduce both the shape and normalization of the ONC's IMF and the mass function of dense cores in Orion. The complex features of the ONC's ...

  16. A rho scaffold integrates the secretory system with feedback mechanisms in regulation of auxin distribution.

    Directory of Open Access Journals (Sweden)

    Ora Hazak

    2010-01-01

    Full Text Available Development in multicellular organisms depends on the ability of individual cells to coordinate their behavior by means of small signaling molecules to form correctly patterned tissues. In plants, a unique mechanism of directional transport of the signaling molecule auxin between cells connects cell polarity and tissue patterning and thus is required for many aspects of plant development. Direction of auxin flow is determined by polar subcellular localization of PIN auxin efflux transporters. Dynamic PIN polar localization results from the constitutive endocytic cycling to and from the plasma membrane, but it is not well understood how this mechanism connects to regulators of cell polarity. The Rho family small GTPases ROPs/RACs are master regulators of cell polarity, however their role in regulating polar protein trafficking and polar auxin transport has not been established. Here, by analysis of mutants and transgenic plants, we show that the ROP interactor and polarity regulator scaffold protein ICR1 is required for recruitment of PIN proteins to the polar domains at the plasma membrane. icr1 mutant embryos and plants display an a array of severe developmental aberrations that are caused by compromised differential auxin distribution. ICR1 functions at the plasma membrane where it is required for exocytosis but does not recycle together with PINs. ICR1 expression is quickly induced by auxin but is suppressed at the positions of stable auxin maxima in the hypophysis and later in the embryonic and mature root meristems. Our results imply that ICR1 is part of an auxin regulated positive feedback loop realized by a unique integration of auxin-dependent transcriptional regulation into ROP-mediated modulation of cell polarity. Thus, ICR1 forms an auxin-modulated link between cell polarity, exocytosis, and auxin transport-dependent tissue patterning.

  17. Effective teaching and feedback strategies in the or and beyond.

    Science.gov (United States)

    Champagne, Bradley J

    2013-12-01

    Maintaining a standard of excellence for graduating surgical residents requires a comprehensive and consistent approach to surgical education. The omnipresent and increasing barriers to education must also be recognized and addressed. The implementation of effective teaching strategies is largely dependent on the resources available at each institution and the vision of education. Unfortunately, allocating time for surgeons to teach both inside and outside the operating room has become a foreign concept to administration. Furthermore, the reduction in case numbers performed by trainees now demands "quality over quantity" to ensure success. Quality teaching moments will only be realized when emphasis is placed on preparation, useful instruction during the procedure, and postoperative feedback. Ideal preparation entails a detailed discussion between the trainee and surgeon about the specific learning goals for the case. During the procedure, the faculty surgeon must strive to maximize the experience through effective communication while performing an efficient and safe operation. Numerous validated objective assessment tools exist for postprocedure evaluation but are grossly underutilized. Surgical education must thoughtfully be approached with the same fervor and detail as patient care. As faculty, it is our responsibility to train the next generation of surgeons and therefore "every case must count."

  18. Effect of task-related continuous auditory feedback during learning of tracking motion exercises

    Directory of Open Access Journals (Sweden)

    Rosati Giulio

    2012-10-01

    Full Text Available Abstract Background This paper presents the results of a set of experiments in which we used continuous auditory feedback to augment motor training exercises. This feedback modality is mostly underexploited in current robotic rehabilitation systems, which usually implement only very basic auditory interfaces. Our hypothesis is that properly designed continuous auditory feedback could be used to represent temporal and spatial information that could in turn, improve performance and motor learning. Methods We implemented three different experiments on healthy subjects, who were asked to track a target on a screen by moving an input device (controller with their hand. Different visual and auditory feedback modalities were envisaged. The first experiment investigated whether continuous task-related auditory feedback can help improve performance to a greater extent than error-related audio feedback, or visual feedback alone. In the second experiment we used sensory substitution to compare different types of auditory feedback with equivalent visual feedback, in order to find out whether mapping the same information on a different sensory channel (the visual channel yielded comparable effects with those gained in the first experiment. The final experiment applied a continuously changing visuomotor transformation between the controller and the screen and mapped kinematic information, computed in either coordinate system (controller or video, to the audio channel, in order to investigate which information was more relevant to the user. Results Task-related audio feedback significantly improved performance with respect to visual feedback alone, whilst error-related feedback did not. Secondly, performance in audio tasks was significantly better with respect to the equivalent sensory-substituted visual tasks. Finally, with respect to visual feedback alone, video-task-related sound feedback decreased the tracking error during the learning of a novel

  19. Generic Reflective Feedback: An Effective Approach to Developing Clinical Reasoning Skills

    Science.gov (United States)

    Wojcikowski, K.; Brownie, S.

    2013-01-01

    Problem-based learning can be an effective tool to develop clinical reasoning skills. However, it traditionally takes place in tutorial groups, giving students little flexibility in how and when they learn. This pilot study compared the effectiveness of generic reflective feedback (GRF) with tutorial-based reflective feedback on the development of…

  20. Distributed feedback quantum cascade lasers operating in continuous-wave mode at λ ≈ 7.6 μm

    Science.gov (United States)

    Jinchuan, Zhang; Lijun, Wang; Wanfeng, Liu; Fengqi, Liu; Lihua, Zhao; Shenqiang, Zhai; Junqi, Liu; Zhanguo, Wang

    2012-02-01

    Distributed feedback (DFB) quantum cascade lasers (QCLs) in continuous-wave (CW) mode emitting at λ ≈ 7.6 μm are presented. Holographic lithography was used to fabricate the first-order distributed feedback grating. For a high-reflectivity-coated QCL with 14.5-μm-wide and 3-mm-long cavity, CW output powers of 300 mW at 85 K and still 10 mW at 270 K are obtained. Single-mode emission with a side-mode suppression ratio (SMSR) of about 30 dB and a wide tuning range of ~300 nm in the temperature range from 85 to 280 K is observed.

  1. Effects of visual and auditory feedback on sensorimotor circuits in the basal ganglia.

    Science.gov (United States)

    Prodoehl, Janey; Yu, Hong; Wasson, Pooja; Corcos, Daniel M; Vaillancourt, David E

    2008-06-01

    Previous work using visual feedback has identified two distinct sensorimotor circuits in the basal ganglia (BG): one that scaled with the duration of force and one that scaled with the rate of change of force. The present study compared functional MRI signal changes in the BG during a grip force task using either visual or auditory feedback to determine whether the BG nuclei process auditory and visual feedback similarly. We confirmed the same two sensorimotor circuits in the BG. Activation in the striatum and external globus pallidus (GPe) scaled linearly with the duration of force under visual and auditory feedback conditions, with similar slopes and intercepts across feedback type. The pattern of signal change for the internal globus pallidus (GPi) and subthalamic nucleus (STN) was nonlinear and parameters of the exponential function were altered by feedback type. Specifically, GPi and STN activation decreased exponentially with the rate of change of force. The rate constant and asymptote of the exponential functions for GPi and STN were greater during auditory than visual feedback. In a comparison of the BOLD signal between BG regions, GPe had the highest percentage of variance accounted for and this effect was preserved for both feedback types. These new findings suggest that neuronal activity of specific BG nuclei is affected by whether the feedback is derived from visual or auditory inputs. Also, the data are consistent with the hypothesis that the GPe has a high level of information convergence from other BG nuclei, which is preserved across different sensory feedback modalities.

  2. Supporting driver headway choice: the effects of discrete headway feedback when following headway instructions.

    Science.gov (United States)

    Risto, Malte; Martens, Marieke H

    2014-07-01

    With specific headway instructions drivers are not able to attain the exact headways as instructed. In this study, the effects of discrete headway feedback (and the direction of headway adjustment) on headway accuracy for drivers carrying out time headway instructions were assessed experimentally. Two groups of each 10 participants (one receiving headway feedback; one control) carried out headway instructions in a driving simulator; increasing and decreasing their headway to a target headway of 2 s at speeds of 50, 80, and 100 km/h. The difference between the instructed and chosen headway was a measure for headway accuracy. The feedback group heard a sound signal at the moment that they crossed the distance of the instructed headway. Unsupported participants showed no significant difference in headway accuracy when increasing or decreasing headways. Discrete headway feedback had varying effects on headway choice accuracy. When participants decreased their headway, feedback led to higher accuracy. When increasing their headway, feedback led to a lower accuracy, compared to no headway feedback. Support did not affect driver's performance in maintaining the chosen headway. The present results suggest that (a) in its current form discrete headway feedback is not sufficient to improve the overall accuracy of chosen headways when carrying out headway instructions; (b) the effect of discrete headway feedback depends on the direction of headway adjustment. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  3. Generation of intense 10-ps, 193-nm pulses using simple distributed feedback dye lasers and an ArF(*) amplifier.

    Science.gov (United States)

    Hatten, D L; Cui, Y; Iii, W T; Mikes, T; Goldhar, J

    1992-11-20

    A pair of holographic distributed feedback dye lasers is used to generate 10-ps pulses at two selected wavelengths that are mixed in a BBO crystal to produce a pulse ~ 10 ps in duration at 193 nm. This seed pulse is subsequently amplified in an ArF(*) excimer laser to an energy of 10-15 mJ with <40 microJ in amplified spontaneous emission. The pulses are nearly transform limited and diffraction limited.

  4. The effect of time headway feedback on following behaviour.

    Science.gov (United States)

    Fairclough, S H; May, A J; Carter, C

    1997-05-01

    A field study was conducted to assess the impact of continuous time headway feedback on following behaviour. An equipped vehicle was fitted with a microwave radar connected to a head-down display. The display was supplemented by an auditory tone which sounded if headway decreased below 1 second. Sixteen subjects participated in five consecutive sessions conducted on a U.K. motorway. The presence of the system and the time of the journey (i.e. rush hour vs off-peak) was manipulated across the experimental sessions. Results revealed that the presence of the system reduced the proportion of time the subjects spent at low headways (e.g. headways and (b) those scenarios characterised as following a lead vehicle at a constant velocity. The presence of the system increased time headway to a lead vehicle when an overtaking manoeuvre was initiated, but only in off-peak traffic. The system had no significant effect on speed-keeping behaviour or driver's mental workload.

  5. Effects of the amount of feedback information on urban traffic with advanced traveler information system

    Science.gov (United States)

    Chen, Jie; Li, Ming; Jiang, Rui; Hu, Mao-Bin

    2017-09-01

    In a real traffic system, information feedback has already been proven to be a good way to alleviate traffic jams. However, due to the massive traffic information of real system, the procedure is often difficult in practice. In this paper, we study the effects of the amount of feedback information based on a cellular automaton model of urban traffic. What we found most interesting is that when providing the traffic information of a part of a road to travelers, the performance of the system will be better than that providing the road's full traffic information. From this basis, we can provide more effective routing strategy with less information. We demonstrate that only providing the traffic information of about first half road from upstream to downstream can maximize the traffic capacity of the system. We also give an explanation for these phenomena by studying the distribution pattern of vehicles and the detailed turning environment at the intersections. The effects of the traffic light period are also provided.

  6. Reflected Power Measurement of Antennas between 0 and 4 GHz Using Optical Mixing of Distributed Feedback Lasers

    Directory of Open Access Journals (Sweden)

    A. Garcia Juarez

    2013-12-01

    Full Text Available Reflected power measurement of antennas by using an alternative microwave photonic system is presented in this paper. The proposed experimental setup is based on optical mixing of two distributed feedback (DFB lasers, where combined beams are detected by a photo-detector. The resulting photocurrent corresponds to a microwave signal which is continuously tuned on bandwidths from 0 to 4 GHz. The obtained swept frequency is applied to an antenna in order to measure its reflected power. Error sources that limit the measurement accuracy of optical mixing such as effect of power deviation in the linewidth of the beat signal and errors introduced by extra fixture are studied. Results of the measurements obtained with the proposed photonic technique are calibrated and compared with traditional electrical measurements. The most important motivation on the use of the proposed technique in this paper lies in that with a simple configuration we were able to characterize microwave devices in a very wide frequency range, avoiding the use of a vector network analyzer (VNA, and thus, a complicated and tedious calibration procedure, contributing to the field of instrumentation and characterization by using photonic techniques.

  7. Correcting students’ written grammatical errors: The effects of negotiated versus nonnegotiated feedback

    Directory of Open Access Journals (Sweden)

    Hossein Nassaji

    2011-10-01

    Full Text Available A substantial number of studies have examined the effects of grammar correction on second language (L2 written errors. However, most of the existing research has involved unidirectional written feedback. This classroom-based study examined the effects of oral negotiation in addressing L2 written errors. Data were collected in two intermediate adult English as a second language classes. Three types of feedback were compared: nonnegotiated direct reformulation, feedback with limited negotiation (i.e., prompt + reformulation and feedback with negotiation. The linguistic targets chosen were the two most common grammatical errors in English: articles and prepositions. The effects of feedback were measured by means of learner-specific error identification/correction tasks administered three days, and again ten days, after the treatment. The results showed an overall advantage for feedback that involved negotiation. However, a comparison of data per error types showed that the differential effects of feedback types were mainly apparent for article errors rather than preposition errors. These results suggest that while negotiated feedback may play an important role in addressing L2 written errors, the degree of its effects may differ for different linguistic targets.

  8. 非均质Euler-bernoulli梁的局部反馈定问题%Locally Distributed Feedback Stabilization of Nonuniform Euler-Bernoulli Beam

    Institute of Scientific and Technical Information of China (English)

    闫庆旭; 侯瑞鸿; 冯德兴; 齐剑冷

    2005-01-01

    In this article, we study the locally distributed feedback stabilization problem of a nonuniform Euler-Bernoulli beam. Firstly, using the semi-group theory, we establish the wellposedness of the associated closed loop system. Then by proving the uniqueness of the solution to a related ordinary differential equation, we derive the asymptotic stability of the closed loop system. Finally, by means of the piecewise multiplier method, we prove that, by either one distributed force feedback or a distributed moment feedback control, the closed loop system can be exponentially stabilized.

  9. The Effects of Graphic Feedback, Goal-Setting, and Manager Praise on Customer Service Behaviors

    Science.gov (United States)

    Loewy, Shannon; Bailey, Jon

    2007-01-01

    The current study used a multiple baseline design to investigate the effects of graphic feedback, goal setting, and manager praise on customer service behaviors in a large retail setting. Direct observation of customer greeting, eye contact, and smiling was used to collect data. After baseline data were collected feedback graphs were posted twice…

  10. Effects of visual feedback therapy on postural control in bilateral standing after stroke: a systematic review.

    NARCIS (Netherlands)

    Peppen, R.P. van; Kortsmit, M.; Lindeman, E.; Kwakkel, G.

    2006-01-01

    OBJECTIVE: To establish whether bilateral standing with visual feedback therapy after stroke improves postural control compared with conventional therapy and to evaluate the generalization of the effects of visual feedback therapy on gait and gait-related activities. DESIGN: A systematic review. MET

  11. Effects of Phonological Feedback on the Selection of Syntax: Evidence from Between-Language Syntactic Priming

    Science.gov (United States)

    Bernolet, Sarah; Hartsuiker, Robert J.; Pickering, Martin J.

    2012-01-01

    Research on word production in bilinguals has often shown an advantage for cognate words. According to some accounts, this cognate effect is caused by feedback from a level that represents information about phonemes (or graphemes) to a level concerned with the word. In order to investigate whether phonological feedback influences the selection of…

  12. From "Hello" to Higher-Order Thinking: The Effect of Coaching and Feedback on Online Chats

    Science.gov (United States)

    Stein, David S.; Wanstreet, Constance E.; Slagle, Paula; Trinko, Lynn A.; Lutz, Michelle

    2013-01-01

    This exploratory study examined the effect of a coaching and feedback intervention in teaching presence and social presence on higher-order thinking in an online community of inquiry. Coaching occurred before each chat, and feedback was provided immediately afterwards. The findings suggest that over time, the frequency of higher-order thinking…

  13. Effects of Training and Coaching with Performance Feedback on Teachers' Use of "Pyramid Model" Practices

    Science.gov (United States)

    Hemmeter, Mary Louise; Hardy, Jessica K.; Schnitz, Alana G.; Adams, Jessie Morris; Kinder, Kiersten A.

    2015-01-01

    Training and coaching with performance feedback has been effective for supporting teachers to use evidence-based instructional practices. However, coaching with performance feedback has primarily been used to support teachers to use discrete skills, and there has been little evidence of maintenance and generalization. The purpose of this study was…

  14. Effectiveness of a training program in supervisors' ability to provide feedback on residents' communication skills

    NARCIS (Netherlands)

    Junod Perron, N.; Nendaz, M.; Louis-Simonet, M.; Sommer, J.; Gut, A.; Baroffio, A.; Dolmans, D.; Vleuten, C.P.M. van der

    2013-01-01

    Teaching communication skills (CS) to residents during clinical practice remains problematic. Direct observation followed by feedback is a powerful way to teach CS in clinical practice. However, little is known about the effect of training on feedback skills in this field. Controlled studies are sca

  15. Effectiveness of a training program in supervisors' ability to provide feedback on residents' communication skills

    NARCIS (Netherlands)

    Junod Perron, N.; Nendaz, M.; Louis-Simonet, M.; Sommer, J.; Gut, A.; Baroffio, A.; Dolmans, D.; Vleuten, C.P.M. van der

    2013-01-01

    Teaching communication skills (CS) to residents during clinical practice remains problematic. Direct observation followed by feedback is a powerful way to teach CS in clinical practice. However, little is known about the effect of training on feedback skills in this field. Controlled studies are

  16. Evaluating the Relative Effects of Feedback and Contingent Money for Staff Training of Stimulus Preference Assessments

    Science.gov (United States)

    Roscoe, Eileen M.; Fisher, Wayne W.; Glover, Ashley C.; Volkert, Valerie M.

    2006-01-01

    Performance feedback has facilitated the acquisition and maintenance of a wide range of behaviors (e.g., health-care routines, seat-belt use). Most researchers have attributed the effectiveness of performance feedback to (a) its discriminative functions, (b) its reinforcing functions, or (c) the combination of the two. In this study, we attempted…

  17. The Effects of Delay of Feedback on a Delayed Concept Formation Transfer Task.

    Science.gov (United States)

    Schroth, Marvin L.

    1992-01-01

    Delay and completeness of verbal information feedback were investigated within a transfer of learning paradigm involving concept formation. An experiment with 192 undergraduates indicates that, although delay of feedback (up to 30 seconds) slows speed of learning on the initial task, it has positive effects on the transfer task. (SLD)

  18. From "Hello" to Higher-Order Thinking: The Effect of Coaching and Feedback on Online Chats

    Science.gov (United States)

    Stein, David S.; Wanstreet, Constance E.; Slagle, Paula; Trinko, Lynn A.; Lutz, Michelle

    2013-01-01

    This exploratory study examined the effect of a coaching and feedback intervention in teaching presence and social presence on higher-order thinking in an online community of inquiry. Coaching occurred before each chat, and feedback was provided immediately afterwards. The findings suggest that over time, the frequency of higher-order thinking…

  19. Effectiveness of Using Screencast Feedback on EFL Students' Writing and Perception

    Science.gov (United States)

    Ali, Amira Desouky

    2016-01-01

    This mixed-methods research was carried out to investigate the effect of screencast video feedback on the writing of freshmen, studying academic writing course at a university in Egypt, and explore their perception towards receiving screencast feedback. Two classes of 63 students were chosen to participate in this study and were assigned into two…

  20. The Effectiveness of Written Corrective Feedback and the Impact Lao Learners' Beliefs Have on Uptake

    Science.gov (United States)

    Rummel, Stephanie; Bitchener, John

    2015-01-01

    This article presents the results of a study examining the effectiveness of written corrective feedback (CF) on the simple past tense and the impact beliefs may have on students' uptake of the feedback they receive. A seven-week study was carried out with 42 advanced EFL learners in Vientiane, Laos. Students' beliefs about written CF were first…

  1. The Effects of X-Ray Feedback from AGN on Host Galaxy Evolution

    CERN Document Server

    Hambrick, D Clay; Naab, Thorsten; Johansson, Peter H

    2011-01-01

    Hydrodynamic simulations of galaxies with active galactic nuclei (AGN) have typically employed feedback that is purely local: i.e., an injection of energy to the immediate neighborhood of the black hole. We perform GADGET-2 simulations of massive elliptical galaxies with an additional feedback component: an observationally calibrated X-ray radiation field which emanates from the black hole and heats gas out to large radii from the galaxy center. We find that including the heating and radiation pressure associated with this X-ray flux in our simulations enhances the effects which are commonly reported from AGN feedback. This new feedback model is twice as effective as traditional feedback at suppressing star formation, produces 3 times less star formation in the last 6 Gyr, and modestly lowers the final BH mass (30%). It is also significantly more effective than an X-ray background in reducing the number of satellite galaxies.

  2. Effects of altered auditory feedback across effector systems: production of melodies by keyboard and singing.

    Science.gov (United States)

    Pfordresher, Peter Q; Mantell, James T

    2012-01-01

    We report an experiment that tested whether effects of altered auditory feedback (AAF) during piano performance differ from its effects during singing. These effector systems differ with respect to the mapping between motor gestures and pitch content of auditory feedback. Whereas this action-effect mapping is highly reliable during phonation in any vocal motor task (singing or speaking), mapping between finger movements and pitch occurs only in limited situations, such as piano playing. Effects of AAF in both tasks replicated results previously found for keyboard performance (Pfordresher, 2003), in that asynchronous (delayed) feedback slowed timing whereas alterations to feedback pitch increased error rates, and the effect of asynchronous feedback was similar in magnitude across tasks. However, manipulations of feedback pitch had larger effects on singing than on keyboard production, suggesting effector-specific differences in sensitivity to action-effect mapping with respect to feedback content. These results support the view that disruption from AAF is based on abstract, effector independent, response-effect associations but that the strength of associations differs across effector systems.

  3. Soliciting feedback: on becoming an effective clinical teacher.

    Science.gov (United States)

    Orlander, J D; Fincke, B G

    1994-06-01

    The art of teaching is difficult to master. When teaching in small groups, as often happens in clinical medicine, there is an opportunity to find out what works by speaking directly with students. The information they provide can serve as an invaluable guide, permitting refinement of skill over time. There are, however, significant barriers to this process. The art lies in finding an approach that is comfortable for both parties. The authors refer to this activity as soliciting feedback. They offer guidelines for soliciting feedback as an aid to improving teaching efforts.

  4. The Effect of Two Types of Corrective Feedback on EFL Learners’ Writing Skill

    Directory of Open Access Journals (Sweden)

    Sina Soltanabadi Farshi

    2015-02-01

    Full Text Available The purpose of this study was to compare the effects of two types of corrective feedback on EFL learners’ writing skill. Thirty five advanced learners in three groups participated in this study. Structures of written texts were taught in all three classes during fourteen sessions of treatment; and each session, a related topic was given and the learners were asked to write about it. In class A, the learners had to deliver their assignments to the teacher in classroom; then the teacher wrote the corrective notes on their papers and gave their papers back the next session. In class B, students had to write their assignments on their electronic instruments, and after that send written tasks via email to the teacher, and he also sent the corrective comments on their errors through email. In class C, as control group, no corrective feedback was given to learners’ errors in their written tasks. Moreover, in class C, learners were free to deliver their writings whether in class or by email. The obtained results showed both methods to be effective since the scores of both experimental groups were significantly higher than the scores of control group, but electronic feedback was more effective and profitable than traditional type; because scores of the learners in group B (Electronic feedback were significantly higher than class C (Traditional feedback. Keywords: writing skill, corrective feedback, electronic feedback, traditional feedback

  5. TRANSIENT QUEUE SIZE DISTRIBUTION SOLUTION OF GEOM/G/1 QUEUE WITH FEEDBACK-A RECURSIVE METHOD

    Institute of Scientific and Technical Information of China (English)

    Chuanyi LUO; Yinghui TANG; Cailiang LI

    2009-01-01

    This paper considers the Geom/G/1 queueing model with feedback according to a late arrival system with delayed access (LASDA). Using recursive method, this paper studies the transient property of the queue size from the initial state N(0+) = I. Some new results about the recursive expression of the transient queue size distribution at any epoch n+ and the recursive formulae of the equilibrium distribution are obtained, Furthermore, the recursive formulae of the equilibrium queue size distribution at epoch n-, and n are obtained, too. The important relations between stationary queue size distributions at different epochs are discovered (being different from the relations given in M/G/1 queueing system). The model discussed in this paper can be widely applied in all kinds of communications and computer network.

  6. The effectiveness of comprehensive corrective feedback in second language writing

    NARCIS (Netherlands)

    van Beuningen, C.G.

    2011-01-01

    Corrective feedback (CF) or error correction is a widely used method of targeting linguistic problems in second language (L2) learners’ writing. The role of CF in the process of acquiring an L2, however, is an issue of considerable controversy in the field of second language acquisition (SLA).

  7. Teaching Accountability: Using Client Feedback to Train Effective Family Therapists

    Science.gov (United States)

    Sparks, Jacqueline A.; Kisler, Tiffani S.; Adams, Jerome F.; Blumen, Dale G.

    2011-01-01

    The AAMFT Task Force on Core Competencies (Nelson et al., 2007) proposed that marriage and family therapy (MFT) educators teach and provide evidence of trainee competence beyond coursework and accrued clinical hours. This article describes the integration of a systematic client feedback protocol into an MFT-accredited program's curricula to…

  8. Effect of corrective feedback for learning verb second

    NARCIS (Netherlands)

    Penning de Vries, B.W.F.; Cucchiarini, C.; Bodnar, S.; Strik, H.; Hout, R.W.N.M. van

    2016-01-01

    This paper presents a detailed study on the role of corrective feedback (CF) in the development of second language (L2) oral proficiency. Learners practiced speaking with a computer-assisted language learning (CALL) system that employs automatic speech recognition (ASR) technology to provide CF. The

  9. Existence and Policy Effectiveness in Feedback Nash LQ-Games

    Directory of Open Access Journals (Sweden)

    Nicola Acocella

    2008-12-01

    Full Text Available This paper illustrates how the classical theory of economic policy can profitably be used to verify some properties of the Linear Nash Feedback Equilibrium in difference LQ-games. In particular, we find that both a necessary condition for the equilibrium existence and a sufficient condition for policy ineffectiveness can be defined in the terms of the simple Tinbergen counting rule.

  10. The effectiveness of comprehensive corrective feedback in second language writing

    NARCIS (Netherlands)

    van Beuningen, C.G.

    2011-01-01

    Corrective feedback (CF) or error correction is a widely used method of targeting linguistic problems in second language (L2) learners’ writing. The role of CF in the process of acquiring an L2, however, is an issue of considerable controversy in the field of second language acquisition (SLA). Quest

  11. Effects of Response-Driven Feedback in Computer Science Learning

    Science.gov (United States)

    Fernandez Aleman, J. L.; Palmer-Brown, D.; Jayne, C.

    2011-01-01

    This paper presents the results of a project on generating diagnostic feedback for guided learning in a first-year course on programming and a Master's course on software quality. An online multiple-choice questions (MCQs) system is integrated with neural network-based data analysis. Findings about how students use the system suggest that the…

  12. Effectiveness of Structural Feedback Provided by Pathfinder Networks

    Science.gov (United States)

    Trumpower, David L.; Sarwar, Gul Shahzad

    2010-01-01

    Within the field of education, there has been an increasing recognition of the importance of formative assessment and of structural knowledge. In an effort to fill needs in each of these areas, this article describes an innovative feedback strategy intended to improve students' structural knowledge. Twenty-four high school physics students were…

  13. Effects of Response-Driven Feedback in Computer Science Learning

    Science.gov (United States)

    Fernandez Aleman, J. L.; Palmer-Brown, D.; Jayne, C.

    2011-01-01

    This paper presents the results of a project on generating diagnostic feedback for guided learning in a first-year course on programming and a Master's course on software quality. An online multiple-choice questions (MCQs) system is integrated with neural network-based data analysis. Findings about how students use the system suggest that the…

  14. Acute stress modulates feedback processing in men and women: differential effects on the feedback-related negativity and theta and beta power.

    Directory of Open Access Journals (Sweden)

    Stella Banis

    Full Text Available Sex-specific prevalence rates in mental and physical disorders may be partly explained by sex differences in physiological stress responses. Neural networks that might be involved are those underlying feedback processing. Aim of the present EEG study was to investigate whether acute stress alters feedback processing, and whether stress effects differ between men and women. Male and female participants performed a gambling task, in a control and a stress condition. Stress was induced by exposing participants to a noise stressor. Brain activity was analyzed using both event-related potential and time-frequency analyses, measuring the feedback-related negativity (FRN and feedback-related changes in theta and beta oscillatory power, respectively. While the FRN and feedback-related theta power were similarly affected by stress induction in both sexes, feedback-related beta power depended on the combination of stress induction condition and sex. FRN amplitude and theta power increases were smaller in the stress relative to the control condition in both sexes, demonstrating that acute noise stress impairs performance monitoring irrespective of sex. However, in the stress but not in the control condition, early lower beta-band power increases were larger for men than women, indicating that stress effects on feedback processing are partly sex-dependent. Our findings suggest that sex-specific effects on feedback processing may comprise a factor underlying sex-specific stress responses.

  15. Effect of biased feedback on motor imagery learning in BCI-teleoperation system

    Directory of Open Access Journals (Sweden)

    Maryam eAlimardani

    2014-04-01

    Full Text Available Feedback design is an important issue in motor imagery BCI systems. Regardless, to date it has not been reported how feedback presentation can optimize co-adaptation between a human brain and such systems. This paper assesses the effect of realistic visual feedback on users’ BC performance and motor imagery skills. We previously developed a tele-operation system for a pair of humanlike robotic hands and showed that BCI control of such hands along with first-person perspective visual feedback of movements can arouse a sense of embodiment in the operators. In the first stage of this study, we found that the intensity of this ownership illusion was associated with feedback presentation and subjects’ performance during BCI motion control. In the second stage, we probed the effect of positive and negative feedback bias on subjects’ BCI performance and motor imagery skills. Although the subject specific classifier, which was set up at the beginning of experiment, detected no significant change in the subjects’ online performance, evaluation of brain activity patterns revealed that subjects’ self-regulation of motor imagery features improved due to a positive bias of feedback and a possible occurrence of ownership illusion. Our findings suggest that in general training protocols for BCIs, manipulation of feedback can play an important role in the optimization of subjects’ motor imagery skills.

  16. Does Grading Undermine Feedback? the Influence of Grades on the Effectiveness of Corrective Feedback on L2 Writing

    Science.gov (United States)

    Dlaska, Andrea; Krekeler, Christian

    2017-01-01

    It has been questioned whether students notice, act upon and, ultimately, learn from feedback if feedback about a task is received in conjunction with grades. If grades undermine feedback, it could be argued that it is a waste of teachers' time to add comments to students' written work if the students also receive grades. With reference to SLA…

  17. Group support system and explanatory feedback: An experimental study of mitigating halo effect

    Directory of Open Access Journals (Sweden)

    Intiyas Utami

    2015-12-01

    Full Text Available Comprehensive assessment potentially leads to halo effect that will affect accuracy of auditors decision-making process. Biased initial audit decision will potentially influence final audit decision. It is there-fore necessary to mitigate halo effect that is the consequence of auditors good impression on clients initial condition. This re-search aims to empirically show that halo effect can be mitigated by explanatory feedback and Group Support System (GSS. The researchers experimentally mani-pulate explanatory feedback and GSS using online web-site. The subjects are stu-dents who have already taken auditing courses. The results show that: 1 explanato-ry feedback can mitigate halo effect so that audit decision will be more accurate 2 GSS can also mitigate halo effect 3 explanatory feedback and GSS are the best me-thods to mitigate halo effect.

  18. Feedback control for distributed heat transfer mechanisms in direct-contact membrane distillation system

    KAUST Repository

    Eleiwi, Fadi

    2015-09-21

    In this paper, the problem of stabilization and production rate reference tracking for a Direct-Contact Membrane Distillation (DCMD) system is addressed. Sufficient conditions for the asymptotic and exponential stabilization for DCMD system are presented using the Gronwall-Bellman lemma and Linear Matrix Inequalities (LMIs) approaches, respectively. A nonlinear observer is then proposed to estimate the temperature distribution among the DCMD domain. This contributes to propose a reference production rate control design for the DCMD process via observer-based output control approach. Finally, numerical simulations are given to show the effectiveness of the proposed methods.

  19. The effect of manipulated and accurate assessment feedback on the self-efficacy of dance students.

    Science.gov (United States)

    García-Dantas, Ana; Quested, Eleanor

    2015-03-01

    Research undertaken with athletes has shown that lower-evaluated feedback is related to low self-efficacy levels. However, the relationship between teacher feedback and self-efficacy has not been studied in the dance setting. In sports or dance contexts, very few studies have manipulated feedback content to examine its impact on performers' self-efficacy in relation to the execution of a specific movement. Therefore, the aim of this investigation was to explore the effect of manipulated upper, lower, and accurate grade feedback on changes in dancers' self-efficacy levels for the execution of the "Zapateado" (a flamenco foot movement). Sixty-one students (56 female, 5 male, ages 13 to 22 ± 3.25 years) from a Spanish dance conservatory participated in this experimental study. They were randomly divided into four feedback groups: 1. upper-evaluated, 2. objective and informational, 3. lower-evaluated, and 4. no feedback-control. Participants performed three trials during a 1-hour session and completed questionnaires tapping self-efficacy pre-feedback and post-feedback. After each trial, teachers (who were confederates in the study) were first asked to rate their perception of each dancer's competence level at performing the movement according to conventional criteria (scores from 0 to 10). The results were then manipulated, and students accurate, lower-evaluated, or upper-evaluated scores were given. Those in the accurate feedback group reported positive change in self-efficacy, whereas those in the lower-evaluated group showed no significant change in self-efficacy during the course of the trial. Findings call into question the common perception among teachers that it can be motivating to provide students with inaccurate feedback that indicates that the students' performance level is much better or much worse than they actually perceive it to be. Self-efficacy appears most likely to increase in students when feedback is accurate.

  20. Facilitating effects of deep brain stimulation on feedback learning in Parkinson's disease.

    Science.gov (United States)

    Meissner, Sarah Nadine; Südmeyer, Martin; Keitel, Ariane; Pollok, Bettina; Bellebaum, Christian

    2016-10-15

    Deep brain stimulation (DBS) of the subthalamic nucleus (STN) provides an effective treatment for Parkinson's disease (PD) motor symptoms. However, findings of effects on cognitive function such as feedback learning remain controversial and rare. The aim of the present study was to gain a better understanding of cognitive alterations associated with STN-DBS. Therefore, we investigated effects of STN-DBS on active and observational feedback learning in PD. 18 PD patients with STN-DBS and 18 matched healthy controls completed active and observational feedback learning tasks. Patients were investigated ON and OFF STN-DBS. Tasks consisted of learning (with feedback) and test phases (without feedback). STN-DBS improved active learning during feedback trials and PD patients ON (but not OFF) STN-DBS showed comparable performance patterns as healthy controls. No STN-DBS effect was found when assessing performance during active test trials without feedback. In this case, however, STN-DBS effects were found to depend on symptom severity. While more impaired patients benefited from STN-DBS, stimulation had no facilitating effect on patients with less severe symptoms. Along similar lines, the severity of motor symptoms tended to be significantly correlated with differences in active test performance due to STN-DBS. For observational feedback learning, there was a tendency for a positive STN-DBS effect with patients reaching the performance level of healthy controls only ON STN-DBS. The present data suggest that STN-DBS facilitates active feedback learning in PD patients. Furthermore, they provide first evidence that STN-DBS might not only affect learning from own but also from observed actions and outcomes.

  1. Differential effects of visual feedback on subjective visual vertical accuracy and precision.

    Directory of Open Access Journals (Sweden)

    Daniel Bjasch

    Full Text Available The brain constructs an internal estimate of the gravitational vertical by integrating multiple sensory signals. In darkness, systematic head-roll dependent errors in verticality estimates, as measured by the subjective visual vertical (SVV, occur. We hypothesized that visual feedback after each trial results in increased accuracy, as physiological adjustment errors (A-/E-effect are likely based on central computational mechanisms and investigated whether such improvements were related to adaptational shifts of perceived vertical or to a higher cognitive strategy. We asked 12 healthy human subjects to adjust a luminous arrow to vertical in various head-roll positions (0 to 120deg right-ear down, 15deg steps. After each adjustment visual feedback was provided (lights on, display of previous adjustment and of an earth-vertical cross. Control trials consisted of SVV adjustments without feedback. At head-roll angles with the largest A-effect (90, 105, and 120deg, errors were reduced significantly (p0.05 influenced. In seven subjects an additional session with two consecutive blocks (first with, then without visual feedback was completed at 90, 105 and 120deg head-roll. In these positions the error-reduction by the previous visual feedback block remained significant over the consecutive 18-24 min (post-feedback block, i.e., was still significantly (p<0.002 different from the control trials. Eleven out of 12 subjects reported having consciously added a bias to their perceived vertical based on visual feedback in order to minimize errors. We conclude that improvements of SVV accuracy by visual feedback, which remained effective after removal of feedback for ≥18 min, rather resulted from a cognitive strategy than by adapting the internal estimate of the gravitational vertical. The mechanisms behind the SVV therefore, remained stable, which is also supported by the fact that SVV precision - depending mostly on otolith input - was not affected by visual

  2. Effects of diaphragm breathing exercise and feedback breathing exercise on pulmonary function in healthy adults.

    Science.gov (United States)

    Yong, Min-Sik; Lee, Hae-Yong; Lee, Yun-Seob

    2017-01-01

    [Purpose] The present study investigated effects of diaphragm breathing exercise and feedback breathing exercise on respiratory function. [Subjects and Methods] Thirty-one subjects were randomly assigned to two groups; the feedback breathing exercise group and the maneuver-diaphragm exercise group. The feedback breathing exercise group was asked to breathe with feedback breathing device, and the maneuver-diaphragm exercise group was asked to perform diaphragm respiration. Respiratory function was evaluated when a subject sat on a chair comfortably. [Results] There was a significant difference in the functional vital capacity and slow vital capacity before and after all breathing exercises. There was a significant between-group difference in functional vital capacity. However, no between-group difference was found in slow vital capacity. [Conclusion] Diaphragm breathing exercise and feedback breathing exercise can affect respiratory function.

  3. Real-time system for studies of the effects of acoustic feedback on animal vocalizations.

    Directory of Open Access Journals (Sweden)

    Mike eSkocik

    2013-01-01

    Full Text Available Studies of behavioral and neural responses to distorted auditory feedback can help shed light on the neural mechanisms of animal vocalizations. We describe an apparatus for generating real-time acoustic feedback. The system can very rapidly detect acoustic features in a song and output acoustic signals if the detected features match the desired acoustic template. The system uses spectrogram-based detection of acoustic elements. It is low-cost and can be programmed for a variety of behavioral experiments requiring acoustic feedback or neural stimulation. We use the system to study the effects of acoustic feedback on birds' vocalizations and demonstrate that such an acoustic feedback can cause both immediate and long-term changes to birds’ songs.

  4. Effects of bandwidth feedback on the automatization of an arm movement sequence.

    Science.gov (United States)

    Agethen, Manfred; Krause, Daniel

    2016-02-01

    We examined the effects of a bandwidth feedback manipulation on motor learning. Effects on movement accuracy, as well as on movement consistency, have been addressed in earlier studies. We have additionally investigated the effects on motor automatization. Because providing error feedback is believed to induce attentional control processes, we suppose that a bandwidth method should facilitate motor automatization. Participants (N=48) were assigned to four groups: one control group and three intervention groups. Participants of the intervention groups practiced an arm movement sequence with 760 trials. The BW0-Group practiced with 100% frequency of feedback. For the BW10-Group, feedback was provided when the errors were larger than 10°. The YokedBW10-Group participants were matched to the feedback schedule of research twins from the BW10-Group. All groups performed pre-tests and retention tests with a secondary task paradigm to test for automaticity. The BW10-Group indicated a higher degree of automatization compared with the BW0-Group, which did not exhibit a change in automaticity. The comparison of the YokedBW10-Group, which also exhibited automatization, and the BW10-Group leads to the proposal that reduction of quantitative feedback frequency and additional positive feedback are responsible for the bandwidth effect. Differences in movement accuracy and consistency were not evident.

  5. Temporal coordination in joint music performance: effects of endogenous rhythms and auditory feedback.

    Science.gov (United States)

    Zamm, Anna; Pfordresher, Peter Q; Palmer, Caroline

    2015-02-01

    Many behaviors require that individuals coordinate the timing of their actions with others. The current study investigated the role of two factors in temporal coordination of joint music performance: differences in partners' spontaneous (uncued) rate and auditory feedback generated by oneself and one's partner. Pianists performed melodies independently (in a Solo condition), and with a partner (in a duet condition), either at the same time as a partner (Unison), or at a temporal offset (Round), such that pianists heard their partner produce a serially shifted copy of their own sequence. Access to self-produced auditory information during duet performance was manipulated as well: Performers heard either full auditory feedback (Full), or only feedback from their partner (Other). Larger differences in partners' spontaneous rates of Solo performances were associated with larger asynchronies (less effective synchronization) during duet performance. Auditory feedback also influenced temporal coordination of duet performance: Pianists were more coordinated (smaller tone onset asynchronies and more mutual adaptation) during duet performances when self-generated auditory feedback aligned with partner-generated feedback (Unison) than when it did not (Round). Removal of self-feedback disrupted coordination (larger tone onset asynchronies) during Round performances only. Together, findings suggest that differences in partners' spontaneous rates of Solo performances, as well as differences in self- and partner-generated auditory feedback, influence temporal coordination of joint sensorimotor behaviors.

  6. ASYNCHRONOUS COMPUTER-MEDIATED CORRECTIVE FEEDBACK AND THE CORRECT USE OF PREPOSITIONS: Is It Really Effective?

    Directory of Open Access Journals (Sweden)

    Seyyed Behrooz HOSSEINI

    2012-08-01

    Full Text Available An area that has recently attracted increasing attention is providing feedback on learners’ writing accuracy through the Internet. However, research in this area has largely focused on synchronous communication, i.e., chatting, with fewer studies assessing asynchronous technologies, i.e., e-mailing. Therefore, this study investigates the effectiveness of asynchronous computer-mediated corrective feedback-explicit and implicit, on increasing the correct use of prepositions. Forty-five Iranian elementary EFL learners at the ILI in Tehran were randomly assigned to two experimental groups, receiving explicit and implicit corrective feedback respectively, and one control group receiving no corrective feedback. Each group included 15 participants. After the treatment, a post-test was administered to assess the probable increase in the correct use of prepositions for the experimental groups compared to the control group. Analysis of the results through a one-way ANOVA revealed that the experimental group 1 who received explicit corrective feedback significantly outperformed the experimental group 2 and the control group. The experimental group 2 who received implicit corrective feedback showed no significant improvement over the experimental group 1 and the control group. Computer-mediated communication, asynchronous CMC, synchronous CMC, the Internet, corrective feedback, e-mail, chat. Although the findings support the current view on feedback through technology, due to the scarcity of research, more investigation is merited as there is much to gain regarding this burgeoning field.

  7. PEER FEEDBACK THROUGH BLOGS: An Effective Tool For Improving Students’ Writing Abilities

    Directory of Open Access Journals (Sweden)

    Orachorn KITCHAKARN

    2013-07-01

    Full Text Available The advancement of computer technology and expansion of the Internet has an increasing impact on writing instruction. The modes of peer feedback have shifted from traditional peer feedback to online peer feedback. This study investigated the effects of peer feedback activity through blogs on students’ writing ability and examined their attitudes towards peer feedback activity. The research was conducted using a single group pretest-posttest design. Blog, the website, was used as a medium for peer feedback activity. Participants were 34 second-year students who studied EN 013 course (English for Expressing Ideas in the first semester of the academic year 2012 at Bangkok University. Two writings tests and a questionnaire were used as instruments for data collection to acquire information. The results revealed that students’ writing scores on the pretest and posttest were significantly different. It can be concluded that peer feedback activity through blogs had a significant role to play in improving students’ writing skill. The students also expressed positive attitudes towards the value of peer feedback activity.

  8. Differential effects of frequency shifted feedback between child and adult stutterers.

    Science.gov (United States)

    Howell, Peter; Sackin, Stevie; Williams, Roberta

    1999-01-01

    It has been reported previously that presentation of an altered form of the voice enhances the fluency of people who stutter. One of these forms of alteration is frequency shifted feedback. The effects of frequency shifted feedback was compared between two speaker groups that differed in age. The fluency enhancing effects of frequency shifted feedback was greater for adult speakers (mean age 21;3) than for children (mean age 9;11). The results are discussed in terms of their implications for theory and treatment.

  9. The effects of feedback and positive reinforcement on the on-task behavior of dancers.

    Science.gov (United States)

    Liberatore, Jennica S; Luyben, Paul D

    2009-01-01

    The purpose of this study was to investigate the effects of feedback on the on-task behavior of adolescent members of a dance company in central New York. The intervention consisted of immediate group and delayed individual feedback. We used a single-subject reversal design. We hypothesized that implementation of the feedback conditions would increase overall on-task rates and decrease variability relative to baseline rates. The data supported this hypothesis with increased on-task rates and decreased variability when the intervention was in effect.

  10. Strong chaos without butterfly effect in dynamical systems with feedback

    CERN Document Server

    Boffetta, G; Vulpiani, A; Boffetta, Guido; Paladin, Giovanni; Vulpiani, Angelo

    1995-01-01

    We discuss the predictability of a conservative system that drives a chaotic system with positive maximum Lyapunov exponent \\lambda_0, such as the erratic motion of an asteroid in the gravitational field of two bodies of much larger mass. We consider the case where in absence of feedback (restricted model), the driving system is regular and completely predictable. A small feedback of strength \\epsilon still allows a good forecasting in the driving system up to a very long time T_p \\sim \\epsilon^{-\\alpha}, where \\alpha depends on the details of the system. The most interesting situation happens when the Lyapunov exponent of the total system is strongly chaotic with \\lambda_{tot} \\approx \\lambda_0 , practically independent of \\epsilon. Therefore an exponential amplification of a small incertitude on the initial conditions in the driving system for any \\epsilon \

  11. Experiments evaluating compliance and force feedback effect on manipulator performance

    Science.gov (United States)

    Kugath, D. A.

    1972-01-01

    The performance capability was assessed of operators performing simulated space tasks using manipulator systems which had compliance and force feedback varied. Two manipulators were used, the E-2 electromechanical man-equivalent (force, reach, etc.) master-slave system and a modified CAM 1400 hydraulic master-slave with 100 lbs force capability at reaches of 24 ft. The CAM 1400 was further modified to operate without its normal force feedback. Several experiments and simulations were performed. The first two involved the E-2 absorbing the energy of a moving mass and secondly, guiding a mass thru a maze. Thus, both work and self paced tasks were studied as servo compliance was varied. Three simulations were run with the E-2 mounted on the CAM 1400 to evaluate the concept of a dexterous manipulator as an end effector of a boom-manipulator. Finally, the CAM 1400 performed a maze test and also simulated the capture of a large mass as the servo compliance was varied and with force feedback included and removed.

  12. Leverage and Feedback Effects on Multifactor Wishart Stochastic Volatility for Option Pricing

    NARCIS (Netherlands)

    M. Asai (Manabu); M.J. McAleer (Michael)

    2013-01-01

    textabstractThe paper proposes a general asymmetric multifactor Wishart stochastic volatility (AMWSV) diffusion process which accommodates leverage, feedback effects and multifactor for the covariance process. The paper gives the closed-form solution for the conditional and unconditional Laplace

  13. Nanoimprinted polymer lasers with threshold below 100 W/cm2 using mixed-order distributed feedback resonators.

    Science.gov (United States)

    Wang, Yue; Tsiminis, Georgios; Kanibolotsky, Alexander L; Skabara, Peter J; Samuel, Ifor D W; Turnbull, Graham A

    2013-06-17

    Organic semiconductor lasers were fabricated by UV-nanoimprint lithography with thresholds as low as 57 W/cm(2) under 4 ns pulsed operation. The nanoimprinted lasers employed mixed-order distributed feedback resonators, with second-order gratings surrounded by first-order gratings, combined with a light-emitting conjugated polymer. They were pumped by InGaN LEDs to produce green-emitting lasers, with thresholds of 208 W/cm(2) (102 nJ/pulse). These hybrid lasers incorporate a scalable UV-nanoimprint lithography process, compatible with high-performance LEDs, therefore we have demonstrated a coherent, compact, low-cost light source.

  14. Nonlinear distortion evaluation in a directly modulated distributed feedback laser diode-based fiber-optic cable television transport system

    Science.gov (United States)

    Li, Chung-Yi; Ying, Cheng-Ling; Lin, Chun-Yu; Chu, Chien-An

    2015-12-01

    This study evaluated a directly modulated distributed feedback (DFB) laser diode (LD) for cable TV systems with respect to carrier-to-nonlinear distortion of LDs. The second-order distortion-to-carrier ratio is found to be proportional to that of the second-order coefficient-to-first-order coefficient of the DFB laser diode driving current and to the optical modulation index (OMI). Furthermore, the third-order distortion-to-carrier ratio is proportional to that of the third-order coefficient-to-first-order coefficient of the DFB laser diode driving current, and to the OMI2.

  15. Sideband locking of a single-section semiconductor distributed-feedback laser in an optical phase-lock loop.

    Science.gov (United States)

    Satyan, Naresh; Vasilyev, Arseny; Liang, Wei; Rakuljic, George; Yariv, Amnon

    2009-11-01

    The bandwidth and performance of optical phase-lock loops (OPLLs) using single-section semiconductor lasers (SCLs) are severely limited by the nonuniform frequency modulation response of the lasers. It is demonstrated that this restriction is eliminated by the sideband locking of a single-section distributed-feedback SCL to a master laser in a heterodyne OPLL, thus enabling a delay-limited loop bandwidth. The lineshape of the phase-locked SCL output is characterized using a delayed self-heterodyne measurement.

  16. Simulation of the Optimized Structure of a Laterally Coupled Distributed Feedback (LC-DFB Semiconductor Laser Above Threshold

    Directory of Open Access Journals (Sweden)

    M. Seifouri

    2013-10-01

    Full Text Available In this paper, the laterally coupled distributed feedback semiconductor laser is studied. In the simulations performed, variations of structural parameters such as the grating amplitude a, the ridge width W, the thickness of the active region d, and other structural properties are considered. It is concluded that for certain values ​​of structural parameters, the laser maintains the highest output power, the lowest distortion Bragg frequency δL and the smallest changes in the wavelength λ. Above threshold, output power more than 40mW and SMSR values greater than 50 dB were achieved.

  17. Complex coupled distributed feedback laser monolithically integrated with electroabsorption modulator and semiconductor optical amplifier at 1.3-micrometer wavelength

    Science.gov (United States)

    Gerlach, Philipp; Peschke, Martin; Wenger, Thomas; Saravanan, Brem K.; Hanke, Christian; Lorch, Steffen; Michalzik, Rainer

    2006-04-01

    We report on the design and experimental results of monolithically integrated optoelectronic devices containing distributed feedback (DFB) laser, electroabsorption modulator (EAM), and semiconductor optical amplifier (SOA). Common InGaAlAs multiple quantum well (MQW) layers are used in all device sections. The incorporation of local lateral metal gratings in the DFB section enables device fabrication by single-step epitaxial growth. The emission wavelength is λ=1.3 micrometer. More than 2 mW single-mode fiber-coupled output power as well as 10 dB/2 V static extinction ratio have been achieved. Modulation experiments clearly show 10 Gbit/s capability.

  18. A novel feedback control system – Controlling the material flow in deep drawing using distributed blank-holder force

    DEFF Research Database (Denmark)

    Endelt, Benny Ørtoft; Tommerup, Søren; Danckert, Joachim

    2013-01-01

    The performance of a feedback control system is often limited by the quality of the model on which it is based, and often the controller design is based on trial and error due to insufficient modeling capabilities. A framework is proposed where the controller design is based on classical state...... on a deep drawing operation where the objective was to control material flow throughout the part using only spatial information regarding flange draw-in. The control system controls both the magnitude and distribution of the blank-holder force. The methodology proved stable and flexible with respect...

  19. The Effect of Six Different Corrective Feedback Strategies on Iranian English Language Learners’ IELTS Writing Task 2

    National Research Council Canada - National Science Library

    Sanavi, Reza Vahdani; Nemati, Majid

    2014-01-01

    Scholars have long studied the effect of corrective feedback strategies on the writing ability of language learners, but few have formed designs in which more than three feedback strategies have been used...

  20. Effects of Stratospheric Ozone Depletion, Solar UV Radiation, and Climate Change on Biogeochemical Cycling: Interactions and Feedbacks

    Science.gov (United States)

    Climate change modulates the effects of solar UV radiation on biogeochemical cycles in terrestrial and aquatic ecosystems, particularly for carbon cycling, resulting in UV-mediated positive or negative feedbacks on climate. Possible positive feedbacks discussed in this assessment...

  1. Effects of Stratospheric Ozone Depletion, Solar UV Radiation, and Climate Change on Biogeochemical Cycling: Interactions and Feedbacks

    Science.gov (United States)

    Climate change modulates the effects of solar UV radiation on biogeochemical cycles in terrestrial and aquatic ecosystems, particularly for carbon cycling, resulting in UV-mediated positive or negative feedbacks on climate. Possible positive feedbacks discussed in this assessment...

  2. Randomized trial of the effect of video feedback on the acquisition of surgical skills.

    Science.gov (United States)

    Farquharson, A L; Cresswell, A C; Beard, J D; Chan, P

    2013-10-01

    Constructive feedback provides a mechanism for reinforcing learning during the acquisition of surgical skills. Feedback is usually given verbally, and sometimes documented, after direct observation by a trained assessor. The aim was to evaluate video recording as an effective modality for enhancing feedback, in comparison with standard verbal feedback alone. This was a prospective, blinded, randomized clinical trial comparing standard verbal feedback plus video with standard verbal feedback alone. Validated pro formas for assessment were used and quality control was performed by independent expert assessors. Trial participants were recorded on video performing the surgical skill, and returned the next day to perform the skill again following video and standard verbal feedback (group 1) or standard verbal feedback alone (group 2). Forty-eight participants were divided equally between the two groups. There was a significant improvement in the mean overall procedure score for group 1 of 2·875 from a maximum achievable score of 20 (P = 0·003), but not for group 2. There were significant improvements in the specific domains of instrument familiarity, needle handling, skin handling and accurate apposition, again all in group 1. The only significant improvement in group 2 was in an organized approach to the task, also observed in group 1. Knot-tying security deteriorated after feedback in group 2 but not in group 1. The addition of video feedback can improve the acquisition of surgical skills, and could be incorporated into formal surgical curricula. © 2013 British Journal of Surgery Society Ltd. Published by John Wiley & Sons Ltd.

  3. Effects of spike-triggered negative feedback on receptive-field properties.

    Science.gov (United States)

    Urdapilleta, Eugenio; Samengo, Inés

    2015-04-01

    Sensory neurons are often described in terms of a receptive field, that is, a linear kernel through which stimuli are filtered before they are further processed. If information transmission is assumed to proceed in a feedforward cascade, the receptive field may be interpreted as the external stimulus' profile maximizing neuronal output. The nervous system, however, contains many feedback loops, and sensory neurons filter more currents than the ones representing the transduced external stimulus. Some of the additional currents are generated by the output activity of the neuron itself, and therefore constitute feedback signals. By means of a time-frequency analysis of the input/output transformation, here we show how feedback modifies the receptive field. The model is applicable to various types of feedback processes, from spike-triggered intrinsic conductances to inhibitory synaptic inputs from nearby neurons. We distinguish between the intrinsic receptive field (filtering all input currents) and the effective receptive field (filtering only external stimuli). Whereas the intrinsic receptive field summarizes the biophysical properties of the neuron associated to subthreshold integration and spike generation, only the effective receptive field can be interpreted as the external stimulus' profile maximizing neuronal output. We demonstrate that spike-triggered feedback shifts low-pass filtering towards band-pass processing, transforming integrator neurons into resonators. For strong feedback, a sharp resonance in the spectral neuronal selectivity may appear. Our results provide a unified framework to interpret a collection of previous experimental studies where specific feedback mechanisms were shown to modify the filtering properties of neurons.

  4. Simulating the effect of AGN feedback on the metal enrichment of galaxy clusters

    CERN Document Server

    Fabjan, D; Tornatore, L; Saro, A; Murante, G; Dolag, K

    2009-01-01

    We present a study of the effect of AGN feedback on metal enrichment and thermal properties of the intracluster medium (ICM) in hydrodynamical simulations. The cosmological simulations are performed for a set of clusters using a version of the TreePM-SPH Gadget code that follows chemo-dynamical evolution by accounting for metal enrichment by different stellar populations. Besides runs not including any efficient form of energy feedback, we carry out simulations including: (i) kinetic feedback in the form of galactic winds triggered by supernova explosions; (ii) AGN feedback from gas accretion onto super-massive black holes (BHs); (iii) AGN feedback in which a 'radio mode' is included. We find that AGN feedback is able to quench star formation in the brightest cluster galaxies at z<4 and provides correct temperature profiles in the central regions of galaxy groups. However, its effect is not sufficient to create cool cores in massive clusters. AGN feedback creates a widespread enrichment in the outskirts of...

  5. Spintronic Oscillator Based on Spin-Current Feedback Using the Spin Hall Effect

    Science.gov (United States)

    Bhuktare, Swapnil; Singh, Hanuman; Bose, Arnab; Tulapurkar, Ashwin. A.

    2017-01-01

    We propose a radio-frequency nano-oscillator based on feedback of spin current into a magnetic tunnel junction (MTJ) with an in-plane magnetized pinned layer and an out-of-plane magnetized free layer. The MTJ is connected to a "feedback" strip of a material like tungsten with a giant spin Hall effect. On passing a dc current through the MTJ, the thermal fluctuations of its free layer produce an oscillatory voltage across itself owing to the magnetoresistance effect. This oscillatory voltage drives an oscillatory current into the tungsten strip which converts this charge current into spin current via the spin Hall effect and feeds it back to the MTJ. We show that this feedback can amplify the fluctuations further and drive the free layer into periodic precessional states. We also propose a way of implementing spin-current feedback by using a nanomagnet coupled to the free layer of the MTJ by dipolar magnetic field.

  6. Telling perfectionists about their perfectionism: Effects of providing feedback on emotional reactivity and psychological symptoms.

    Science.gov (United States)

    Aldea, Mirela A; Rice, Kenneth G; Gormley, Barbara; Rojas, Ariz

    2010-12-01

    A randomized, controlled clinical trial was conducted to determine the efficacy of receiving feedback in a sample of maladaptive perfectionists. A total of 60 young adults were randomly assigned to a feedback intervention or control group. Hierarchical Linear Modeling was utilized to analyze the effects of perfectionism over time, as well as the effects of treatment condition on the relationship between perfectionism and outcomes. Measures of interest included emotional reactivity, self-esteem, and psychological distress. Findings revealed that providing feedback to maladaptive perfectionists reduced self-reported global symptomatic distress as well as emotional reactivity. The results are discussed in light of treatment implications, especially with regard to the manner in which perfectionists respond to therapeutic interventions. Overall, study findings suggest that a brief, low-cost feedback intervention is effective at decreasing psychological distress in maladaptive perfectionists and may serve as a beneficial precursor to individual therapy or counseling.

  7. The Effects of Post-Observational Reflective Feedback Modes on Teaching Beliefs: Peer vs. Teacher-Mediated Feedback

    Directory of Open Access Journals (Sweden)

    İlknur Yüksel

    2011-01-01

    Full Text Available The aim of this study was to investigate whether the pre-service teachers’ language teaching beliefs changed as a result of two different post-observational reflective feedback modes; teacher mediated and peer feedback, during their teaching practice. For each post-observational feedback mode, two groups of eight Turkish pre-service language teachers attending to the final year at English Language Teaching Department at Anadolu University, totally 16 pre-service teachers participated in the study. The qualitative and quantitative data was collected at the beginning and end of the different feedback treatments from each group. The results indicated that the feedback modes on pre-service teachers’ teaching practice could influence their beliefs about teaching. Peer feedback had a potential to change the teachers’ beliefs through critical reflection skills that were fostered as a result of collaboration within the peer group.

  8. The effects of feedback and consequences on transitional cursive letter formation.

    Science.gov (United States)

    Trap, J J; Milner-Davis, P; Joseph, S; Cooper, J O

    1978-01-01

    Twelve first-grade students were employed to analyze the effects of (1) Verbal and Visual Feedback, (2) Verbal and Visual Feedback plus immediate rewriting of trained letters with one or more incorrect letter strokes, and (3) Potential Reinforcement on cursive letter strokes. Students practised both a set of trained and a set of untrained letters during each session. Feedback and reinforcement was administered only for trained letter strokes. The percentage of correct trained letter strokes increased during all conditions. Performance on the untrained but practiced and trained letter strokes followed the same general trend in response pattern. No consistent pattern of generalization was demonstrated with untrained and unpracticed letter strokes.

  9. Context preexposure influences the effectiveness of feedback stimuli in avoidance learning.

    Science.gov (United States)

    Callen, Edward J

    2004-04-30

    According to the effective reinforcement theory of avoidance learning, there is a positive relationship between the level of context fear and the effectiveness of feedback stimuli. The present research used different preexposure treatments to manipulate context fear and to evaluate the effects of feedback stimuli in two-way avoidance learning. Rat subjects received nonreinforced preexposure either to the nonvisual context cues (avoidance apparatus with the houselights extinguished), to the visual context cues (avoidance apparatus with the houselights on but with a Plexiglas floor covering the grids), or to a neutral box. During subsequent avoidance training conditioned stimulus termination was delayed for 5s after an instrumental response and either a flashing light or darkness was presented as a feedback stimulus. Without preexposure, darkness produced better avoidance performance than did the flashing light. Preexposure to the visual context cues decreased the effectiveness of darkness as a feedback stimulus. However, preexposure to either the visual or to the nonvisual context cues facilitated avoidance performance when a flashing light was used as a feedback stimulus. The results suggest that the effects of a feedback stimulus may be dependent upon the amount and source of context fear.

  10. Cycling in the Absence of Task-Related Feedback : Effects on Pacing and Performance

    NARCIS (Netherlands)

    Smits, Benjamin L. M.; Polman, Remco C. J.; Otten, Bert; Pepping, Gert-Jan; Hettinga, Florentina J.

    2016-01-01

    Introduction: To achieve personal goals in exercise task completion, exercisers have to regulate, distribute, and manage their effort. In endurance sports, it has become very commonplace for athletes to consult task -related feedback on external devices to do so. The aim of the present study was to

  11. Effect of a contact monitoring system with immediate visual feedback on hand hygiene compliance.

    Science.gov (United States)

    Storey, S J; FitzGerald, G; Moore, G; Knights, E; Atkinson, S; Smith, S; Freeman, O; Cryer, P; Wilson, A P R

    2014-10-01

    Hand hygiene compliance is traditionally monitored by visual methods that are open to bias and strictly limited in time and place. Automatic monitoring may be more effective for infection control as well as performance management. To establish accuracy and acceptability of an automatic contact monitoring system for hand hygiene. Monitoring equipment was installed across 55 beds in three wards, and included modified identity badges, bedside furniture, sinks and alcohol gel dispensers. Badges were in near-skin contact (through uniform) and could detect alcohol vapour. All devices were linked by wi-fi. A traffic light system on the badge provided immediate feedback to staff and patients on the hand hygiene status of a member of staff on approach to a patient. Compliance was logged automatically. Following a period of immediate feedback, no visual feedback was given for two weeks. Subsequently, feedback was given using red/green lights for 10 days, followed by retrospective feedback to the ward. Hand hygiene was verified independently by an observer. Hand hygiene compliance increased from 21% of 97 opportunities to 66% of 197 opportunities during active immediate feedback. Compliance decreased when feedback was provided to wards retrospectively. Six staff (26%) avoided wearing a badge, saying that it was too heavy or they were not on the ward all day. Only three of 30 patients stated that they would challenge staff who had not performed hand hygiene. Automatic contact monitoring with immediate feedback was effective in increasing hand hygiene compliance, but feedback given retrospectively did not prevent a decrease in compliance. Copyright © 2014 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  12. The Effects of Active Videogame Feedback and Practicing Experience on Children's Physical Activity Intensity and Enjoyment.

    Science.gov (United States)

    Chen, Han; Sun, Haichun

    2017-08-01

    The study aims to explore the effects of receiving active videogame (AVG) feedback and playing experience on individuals' moderate-to-vigorous physical activity (MVPA) and perceived enjoyment. This was a within-subject design study. The participants included 36 (n = 15 and 21 for boys and girls, respectively) fourth graders enrolled in a rural elementary school in southern Georgia area. The experiment lasted for 6 weeks with each week including three sessions. The participants were assigned in either front row (sensor feedback) or back row (no sensor feedback) during practice, which was alternated in different sessions. Two different dance games were played during the study with each game implemented for 3 weeks. The MVPA was measured with GT3X+ accelerometers. Physical activity (PA) enjoyment was assessed after the completion of the first two and last two sessions of each game. A repeated one-way ANOVA (analysis of variance) was used to examine the effects of AVG feedback and game on MVPA. A repeated one-way MANOVA (multivariate analysis of variance) was conducted for each game to examine the effects of experience and AVG feedback on enjoyment and MVPA. No effects of AVG feedback were found for MVPA or enjoyment (P > 0.05). The effects of experience on MVPA were found for Just Dance Kids 2014 with experience decreased MVPA (P < 0.05). Students who practiced dance AVG without receiving feedback still demonstrated positive affection and accumulated similar MVPA than when practicing while receiving feedback. Experience for certain dance games tends to decrease PA intensity.

  13. Single-mode surface-emitting distributed feedback quantum-cascade lasers based on hybrid waveguide structure

    Institute of Scientific and Technical Information of China (English)

    Wanhong Guo; Junqi Liu; Jianyan Chen; Lu Li; Lijun Wang; Fengqi Liu; Zhanguo Wang

    2011-01-01

    Surface-emitting distributed feedback quantum-cascade lasers operating at λ≈7.8 μm are demonstrated.The metal-covered second-order grating is shallow-etched into the surface of a thin InGaAs contact and cladding layer. This forms a hybrid waveguide and used to achieve relatively low waveguide losses and high coupling strengths. The devices exhibit stable single-mode operation from 90 to 130 K with a side mode suppression ratio above 20 dB. A slope efficiency of 194 mW/A is obtained at 90 K, which is twice higher than that of the Fabry-Perot counterpart.%@@ Surface-emitting distributed feedback quantum-cascade lasers operating at λ≈7.8 μm are demonstrated.The metal-covered second-order grating is shallow-etched into the surface of a thin InGaAs contact and cladding layer.This forms a hybrid waveguide and used to achieve relatively low waveguide losses and high coupling strengths.The devices exhibit stable single-mode operation from 90 to 130 K with a side mode suppression ratio above 20 dB.A slope efficiency of 194 mW/A is obtained at 90 K, which is twice higher than that of the Fabry-Perot counterpart.

  14. Auditory feedback and memory for music performance: sound evidence for an encoding effect.

    Science.gov (United States)

    Finney, Steven A; Palmer, Caroline

    2003-01-01

    Research on the effects of context and task on learning and memory has included approaches that emphasize processes during learning (e.g., Craik & Tulving, 1975) and approaches that emphasize a match of conditions during learning with conditions during a later test of memory (e.g., Morris, Bransford, & Franks, 1977; Proteau, 1992; Tulving & Thomson, 1973). We investigated the effects of auditory context on learning and retrieval in three experiments on memorized music performance (a form of serial recall). Auditory feedback (presence or absence) was manipulated while pianists learned musical pieces from notation and when they later played the pieces from memory. Auditory feedback during learning significantly improved later recall. However, auditory feedback at test did not significantly affect recall, nor was there an interaction between conditions at learning and test. Auditory feedback in music performance appears to be a contextual factor that affects learning but is relatively independent of retrieval conditions.

  15. Effects of auditory feedback during gait training on hemiplegic patients' weight bearing and dynamic balance ability.

    Science.gov (United States)

    Ki, Kyong-Il; Kim, Mi-Sun; Moon, Young; Choi, Jong-Duk

    2015-04-01

    [Purpose] This study examined the effects of auditory feedback during gait on the weight bearing of patients with hemiplegia resulting from a stroke. [Subjects] Thirty hemiplegic patients participated in this experiment and they were randomly allocated to an experimental group and a control group. [Methods] Both groups received neuro-developmental treatment for four weeks and the experimental group additionally received auditory feedback during gait training. In order to examine auditory feedback effects on weight bearing during gait, a motion analysis system GAITRite was used to measure the duration of the stance phase and single limb stance phase of the subjects. [Results] The experimental group showed statistically significant improvements in the duration of the stance phase and single limb stance phase of the paretic side and the results of the Timed Up and Go Test after the training. [Conclusion] Auditory feedback during gait training significantly improved the duration of the stance phase and single limb stance phase of hemiplegic stroke patients.

  16. The effect of process delay on dynamical behaviors in a self-feedback nonlinear oscillator

    Science.gov (United States)

    Yao, Chenggui; Ma, Jun; Li, Chuan; He, Zhiwei

    2016-10-01

    The delayed feedback loops play a crucial role in the stability of dynamical systems. The effect of process delay in feedback is studied numerically and theoretically in the delayed feedback nonlinear systems including the neural model, periodic system and chaotic oscillator. The process delay is of key importance in determining the evolution of systems, and the rich dynamical phenomena are observed. By introducing a process delay, we find that it can induce bursting electric activities in the neural model. We demonstrate that this novel regime of amplitude death also exists in the parameter space of feedback strength and process delay for the periodic system and chaotic oscillator. Our results extend the effect of process delay in the paper of Zou et al.(2013) where the process delay can eliminate the amplitude death of the coupled nonlinear systems.

  17. Augmented visual feedback counteracts the effects of surface muscular functional electrical stimulation on physiological tremor.

    Science.gov (United States)

    Grimaldi, Giuliana; Fernandez, Alfredo; Manto, Mario

    2013-09-24

    Recent studies suggest that surface muscular functional electrical stimulation (FES) might suppress neurological upper limb tremor. We assessed its effects on upper limb physiological tremor, which is mainly driven by mechanical-reflex oscillations. We investigated the interaction between FES and augmented visual feedback, since (a) most daily activities are performed using visual cues, and (b) augmented visual feedback exacerbates upper limb tremor. 10 healthy subjects (23.4 ± 7.7 years) performed 2 postural tasks with combinations of FES (4 sites; frequency of stimulation: 30 Hz; pulse width: 300 microsec; range of current delivered 10-34 mAmp) and augmented visual feedback. Spectral analysis of tremor showed a decrease of power spectral density to 62.18% (p = 0.01), of the integral in the 8-12 Hz frequency band to 57.67% (p = 0.003), and of tremor root mean square (RMS) to 57.16% (p = 0.002) during FES, without any changes in tremor frequency. Augmented visual feedback blocked the beneficial effect of FES, as confirmed by power spectral analysis (p = 0.01). We found a statistically significant interaction between augmented visual feedback and electrical stimulation (p = 0.039). Augmented visual feedback antagonizes the effects of FES on physiological tremor. The absence of changes of peak frequency argues against an effect of FES on mechanical properties of the upper limb.

  18. Effects of 3D virtual haptics force feedback on brand personality perception: the mediating role of physical presence in advergames.

    Science.gov (United States)

    Jin, Seung-A Annie

    2010-06-01

    This study gauged the effects of force feedback in the Novint Falcon haptics system on the sensory and cognitive dimensions of a virtual test-driving experience. First, in order to explore the effects of tactile stimuli with force feedback on users' sensory experience, feelings of physical presence (the extent to which virtual physical objects are experienced as actual physical objects) were measured after participants used the haptics interface. Second, to evaluate the effects of force feedback on the cognitive dimension of consumers' virtual experience, this study investigated brand personality perception. The experiment utilized the Novint Falcon haptics controller to induce immersive virtual test-driving through tactile stimuli. The author designed a two-group (haptics stimuli with force feedback versus no force feedback) comparison experiment (N = 238) by manipulating the level of force feedback. Users in the force feedback condition were exposed to tactile stimuli involving various force feedback effects (e.g., terrain effects, acceleration, and lateral forces) while test-driving a rally car. In contrast, users in the control condition test-drove the rally car using the Novint Falcon but were not given any force feedback. Results of ANOVAs indicated that (a) users exposed to force feedback felt stronger physical presence than those in the no force feedback condition, and (b) users exposed to haptics stimuli with force feedback perceived the brand personality of the car to be more rugged than those in the control condition. Managerial implications of the study for product trial in the business world are discussed.

  19. Negotiated media effects. Peer feedback modifies effects of media's thin-body ideal on adolescent girls.

    Science.gov (United States)

    Veldhuis, Jolanda; Konijn, Elly A; Seidell, Jacob C

    2014-02-01

    The present study introduces a theoretical framework on negotiated media effects. Specifically, we argue that feedback of peers on thin-body ideal media images and individual dispositions guide effects on adolescent girls' psychosocial responses to media exposure. Therefore, we examined the thin-body ideal as portrayed in media and peers' feedback on such thin-ideal images in their combined effects on adolescent girls' body dissatisfaction, objectified body consciousness, and social comparison with media models. Hence, media models and peer comments were systematically combined as incorporated entities in YouTube-formats. Hypotheses were tested in a 3 (media models: extremely thin vs. thin vs. normal weight)×3 (peer comments: 6kg-underweight vs. 3kg-underweight vs. normal-weight)×2 (appearance schematicity: lower vs. higher) between-subjects design (N=216). Results showed that peer comments indicating that a media model was 'only 3kg-underweight' exerted most negative responses, particularly in girls who strongly process appearance relevant information. Peer feedback interacts with media models in guiding perceptions of what is considered an 'ideal' body shape. Results highlight the important role of peers as well as individual predispositions in view of understanding how thin-ideal media images may impact adolescent girls' body image concerns.

  20. The role of feedback in improving the effectiveness of workplace based assessments: a systematic review

    Directory of Open Access Journals (Sweden)

    Saedon Habiba

    2012-05-01

    Full Text Available Abstract Background With recent emphasis placed on workplace based assessment (WBA as a method of formative performance assessment, there is limited evidence in the current literature regarding the role of feedback in improving the effectiveness of WBA. The aim of this systematic review was to elucidate the impact of feedback on the effectiveness of WBA in postgraduate medical training. Methods Searches were conducted using the following bibliographic databases to identify original published studies related to WBA and the role of feedback: Medline (1950-December 2010, Embase (1980-December 2010 and Journals@Ovid (English language only, 1996-December 2010. Studies which attempted to evaluate the role of feedback in WBA involving postgraduate doctors were included. Results 15 identified studies met the inclusion criteria and minimum quality threshold. They were heterogeneous in methodological design. 7 studies focused on multi source feedback, 3 studies were based on mini-clinical evaluation exercise, 2 looked at procedural based assessment, one study looked at workplace based assessments in general and 2 studies looked at a combination of 3 to 6 workplace based assessments. 7 studies originated from the United Kingdom. Others were from Canada, the United States and New Zealand. Study populations were doctors in various grades of training from a wide range of specialties including general practice, general medicine, general surgery, dermatology, paediatrics and anaesthetics. All studies were prospective in design, and non-comparative descriptive or observational studies using a variety of methods including questionnaires, one to one interviews and focus groups. Conclusions The evidence base contains few high quality conclusive studies and more studies are required to provide further evidence for the effect of feedback from workplace based assessment on subsequent performance. There is, however, good evidence that if well implemented, feedback from

  1. Auditory Masking Effects on Speech Fluency in Apraxia of Speech and Aphasia: Comparison to Altered Auditory Feedback

    Science.gov (United States)

    Jacks, Adam; Haley, Katarina L.

    2015-01-01

    Purpose: To study the effects of masked auditory feedback (MAF) on speech fluency in adults with aphasia and/or apraxia of speech (APH/AOS). We hypothesized that adults with AOS would increase speech fluency when speaking with noise. Altered auditory feedback (AAF; i.e., delayed/frequency-shifted feedback) was included as a control condition not…

  2. An Examination of the Effectiveness of Embedded Audio Feedback for English as a Foreign Language Students in Asynchronous Online Discussions

    Science.gov (United States)

    Olesova, Larisa A.

    2011-01-01

    This study examined the effect of asynchronous embedded audio feedback on English as a Foreign Language (EFL) students' higher-order learning and perception of the audio feedback versus text-based feedback when the students participated in asynchronous online discussions. In addition, this study examined how the impact and perceptions differed…

  3. Simulated effect of calcification feedback on atmospheric CO2 and ocean acidification

    Science.gov (United States)

    Zhang, Han; Cao, Long

    2016-01-01

    Ocean uptake of anthropogenic CO2 reduces pH and saturation state of calcium carbonate materials of seawater, which could reduce the calcification rate of some marine organisms, triggering a negative feedback on the growth of atmospheric CO2. We quantify the effect of this CO2-calcification feedback by conducting a series of Earth system model simulations that incorporate different parameterization schemes describing the dependence of calcification rate on saturation state of CaCO3. In a scenario with SRES A2 CO2 emission until 2100 and zero emission afterwards, by year 3500, in the simulation without CO2-calcification feedback, model projects an accumulated ocean CO2 uptake of 1462 PgC, atmospheric CO2 of 612 ppm, and surface pH of 7.9. Inclusion of CO2-calcification feedback increases ocean CO2 uptake by 9 to 285 PgC, reduces atmospheric CO2 by 4 to 70 ppm, and mitigates the reduction in surface pH by 0.003 to 0.06, depending on the form of parameterization scheme used. It is also found that the effect of CO2-calcification feedback on ocean carbon uptake is comparable and could be much larger than the effect from CO2-induced warming. Our results highlight the potentially important role CO2-calcification feedback plays in ocean carbon cycle and projections of future atmospheric CO2 concentrations. PMID:26838480

  4. Simulated effect of calcification feedback on atmospheric CO2 and ocean acidification

    Science.gov (United States)

    Zhang, Han; Cao, Long

    2016-02-01

    Ocean uptake of anthropogenic CO2 reduces pH and saturation state of calcium carbonate materials of seawater, which could reduce the calcification rate of some marine organisms, triggering a negative feedback on the growth of atmospheric CO2. We quantify the effect of this CO2-calcification feedback by conducting a series of Earth system model simulations that incorporate different parameterization schemes describing the dependence of calcification rate on saturation state of CaCO3. In a scenario with SRES A2 CO2 emission until 2100 and zero emission afterwards, by year 3500, in the simulation without CO2-calcification feedback, model projects an accumulated ocean CO2 uptake of 1462 PgC, atmospheric CO2 of 612 ppm, and surface pH of 7.9. Inclusion of CO2-calcification feedback increases ocean CO2 uptake by 9 to 285 PgC, reduces atmospheric CO2 by 4 to 70 ppm, and mitigates the reduction in surface pH by 0.003 to 0.06, depending on the form of parameterization scheme used. It is also found that the effect of CO2-calcification feedback on ocean carbon uptake is comparable and could be much larger than the effect from CO2-induced warming. Our results highlight the potentially important role CO2-calcification feedback plays in ocean carbon cycle and projections of future atmospheric CO2 concentrations.

  5. Galaxy-scale AGN Feedback - Theory

    CERN Document Server

    Wagner, A Y; Umemura, M; Sutherland, R S; Silk, J

    2015-01-01

    Powerful relativistic jets in radio galaxies are capable of driving strong outflows but also inducing star-formation by pressure-triggering collapse of dense clouds. We review theoretical work on negative and positive active galactic nuclei feedback, discussing insights gained from recent hydrodynamical simulations of jet-driven feedback on galaxy scales that are applicable to compact radio sources. The simulations show that the efficiency of feedback and the relative importance of negative and positive feedback depends strongly on interstellar medium properties, especially the column depth and spatial distribution of clouds. Negative feedback is most effective if clouds are distributed spherically and individual clouds have small column depths, while positive feedback is most effective if clouds are predominantly in a disc-like configuration.

  6. Distributed Beamforming in Wireless Multiuser Relay-Interference Networks with Quantized Feedback

    CERN Document Server

    Koyuncu, Erdem

    2010-01-01

    We study quantized beamforming in wireless amplify-and-forward relay-interference networks with any number of transmitters, relays, and receivers. We design the quantizer of the channel state information to minimize the probability that at least one receiver incorrectly decodes its desired symbol(s). Correspondingly, we introduce a generalized diversity measure that encapsulates the conventional one as the first-order diversity. Additionally, it incorporates the second-order diversity, which is concerned with the transmitter power dependent logarithmic terms that appear in the error rate expression. First, we show that, regardless of the quantizer and the amount of feedback that is used, the relay-interference network suffers a second-order diversity loss compared to interference-free networks. Then, two different quantization schemes are studied: First, using a global quantizer, we show that a simple relay selection scheme can achieve maximal diversity. Then, using the localization method, we construct both ...

  7. Effectiveness of a web-based health risk assessment with individually-tailored feedback on lifestyle behaviour: study protocol

    Directory of Open Access Journals (Sweden)

    Laan Eva K

    2012-03-01

    Full Text Available Abstract Background Physical inactivity, unhealthy dietary habits, smoking and high alcohol consumption are recognized risk factors for cardiovascular disease and cancer. Web-based health risk assessments with tailored feedback seem promising in promoting a healthy lifestyle. This study evaluates the effectiveness of a web-based health risk assessment with individually-tailored feedback on lifestyle behaviour, conducted in a worksite setting. Methods/Design The web-based health risk assessment starts with a questionnaire covering socio-demographic variables, family and personal medical history, lifestyle behaviour and psychological variables. Prognostic models are used to estimate individual cardiovascular risks. In case of high risk further biometric and laboratory evaluation is advised. All participants receive individually-tailored feedback on their responses to the health risk assessment questionnaire. The study uses a quasi-experimental design with a waiting list control group. Data are collected at baseline (T0 and after six months (T1. Within each company, clusters of employees are allocated to either the intervention or the control group. Primary outcome is lifestyle behaviour, expressed as the sum of five indicators namely physical activity, nutrition, smoking behaviour, alcohol consumption, and symptoms of burnout. Multilevel regression analysis will be used to answer the main research question and to correct for clustering effects. Baseline differences between the intervention and control group in the distribution of characteristics with a potential effect on lifestyle change will be taken into account in further analyses using propensity scores. Discussion This study will increase insight into the effectiveness of health risk assessments with tailored feedback and into conditions that may modify the effectiveness. This information can be used to design effective interventions for lifestyle behaviour change among employees. Trial

  8. The effect of energy feedbacks on continental strength.

    Science.gov (United States)

    Regenauer-Lieb, Klaus; Weinberg, Roberto F; Rosenbaum, Gideon

    2006-07-06

    The classical strength profile of continents is derived from a quasi-static view of their rheological response to stress--one that does not consider dynamic interactions between brittle and ductile layers. Such interactions result in complexities of failure in the brittle-ductile transition and the need to couple energy to understand strain localization. Here we investigate continental deformation by solving the fully coupled energy, momentum and continuum equations. We show that this approach produces unexpected feedback processes, leading to a significantly weaker dynamic strength evolution. In our model, stress localization focused on the brittle-ductile transition leads to the spontaneous development of mid-crustal detachment faults immediately above the strongest crustal layer. We also find that an additional decoupling layer forms between the lower crust and mantle. Our results explain the development of decoupling layers that are observed to accommodate hundreds of kilometres of horizontal motions during continental deformation.

  9. Positive effects of augmented verbal feedback on power production in NCAA Division I collegiate athletes.

    Science.gov (United States)

    Staub, Joseph N; Kraemer, William J; Pandit, Ashley L; Haug, William B; Comstock, Brett A; Dunn-Lewis, Courtenay; Hooper, David R; Maresh, Carl M; Volek, Jeff S; Häkkinen, Keijo

    2013-08-01

    (mean difference 283 ± 109 W, p = 0.022). Also, there was a significant difference in mean power output between feedback and no feedback trials during set 2 (mean difference 240 ± 66 W, p = 0.003) and set 3 (mean difference 299 ± 93 W, p = 0.007). When training for maximal power in a plyometric training protocol, verbal feedback can be used as both a simple and effective aid in producing optimal power outputs.

  10. Effects of feedback accountability and self-rating information on employee appraisals: a replication and extension.

    Science.gov (United States)

    Shore, Ted H; Tashchian, Armen

    2007-06-01

    The influence of feedback accountability and self-rating information on employee performance appraisals was examined. Undergraduate business student participants assumed the role of "supervisor" and evaluated a fictitious "subordinate" whose performance on a clerical task was either moderately poor or very good. Participants were either given fictitious self-rating information, or no self-rating information, and were told they were expected to provide performance feedback to their ratee, or there was no feedback expectation. As expected, in Study 1 both self-rating information and expected feedback-sharing independently resulted in lenient ratings for poor performance, and the combined effects resulted in the highest ratings. By contrast, results for good performance (Study 2) were not significant. Implications of the findings for human resource management practice and research were discussed.

  11. The effect of AGN feedback on the X-ray morphologies of clusters -- simulations vs. observations

    CERN Document Server

    Chon, Gayoung; Boehringer, Hans

    2016-01-01

    We study the effect of Active Nuclei Galaxy (AGN) feedback as one of the major mechanisms modifying the cluster morphology influencing scaling relations, which are the most uncertain factor in constraining cosmology with clusters of galaxies. Using cosmological hydrodynamical simulations we investigate how the AGN feedback changes the X-ray morphology of the simulated systems, and compare to the observed REXCESS (Representative XMM-Newton Cluster Structure Survey) clusters. We apply centre shifts and power ratios to characterise the cluster morphology, and find that our simulated clusters are more substructured than the observed ones. We show that the degree of this discrepancy is affected by the inclusion of AGN feedback. While the clusters simulated with the AGN feedback are in much better agreement with the REXCESS L_X-T relation, they are also more substructured, which increases the tension with observations. This suggests that not only global cluster properties such as L_X and T and radial profiles shoul...

  12. The Effectiveness of Pre-Service English Teachers’ Collaborative Genre-Based Writing Feedback

    Directory of Open Access Journals (Sweden)

    Didik Rinan Sumekto

    2017-05-01

    Full Text Available This study investigated the collaborative genre-based effectiveness among the pre-service English teachers (PSETs. Data collection used the genre-based writing feedback observation upon its reflection and instruction and need analysis questionnaire. The data analysis used multivariate statistics method to generalize the writing tests. The findings showed that the PSETs’ feedback supported the interaction, accountability, and interdependence. These aspects were due to the collaborative participation in groups, in which the PSETs worked with the flexibility, entirely performed the quality, andcontributed in positive attitude during the meetings and assignments. The feedback emphasized the learning improvement within the formative reflection through the general linear model (GLM repeated measures analysis, where F=6,114 and p<0,01. This study concludes that the collaborative genre-based writing feedback has the positive response from the PSETs. The determinant ranges gains in between 85% to 90% after a series of genre-based writing lectures were conducted.

  13. Learning new vocabulary in German: the effects of inferring word meanings, type of feedback, and time of test.

    Science.gov (United States)

    Carpenter, Shana K; Sachs, Riebana E; Martin, Beth; Schmidt, Kristian; Looft, Ruxandra

    2012-02-01

    In the present study, introductory-level German students read a simplified story and learned the meanings of new German words by reading English translations in marginal glosses versus trying to infer (i.e., guess) their translations. Students who inferred translations were given feedback in English or in German, or no feedback at all. Although immediate retention of new vocabulary was better for students who used marginal glosses, students who inferred word meanings and then received English feedback forgot fewer translations over time. Plausible but inaccurate inferences (i.e., those that made sense in the context) were more likely to be corrected by students who received English feedback as compared with German feedback, providing support for the beneficial effects of mediating information. Implausible inaccurate inferences, however, were more likely to be corrected on the delayed vocabulary test by students who received German feedback as compared with English feedback, possibly because of the additional contextual support provided by German feedback.

  14. Effect of auditory feedback differs according to side of hemiparesis: a comparative pilot study

    Directory of Open Access Journals (Sweden)

    Bensmail Djamel

    2009-12-01

    Full Text Available Abstract Background Following stroke, patients frequently demonstrate loss of motor control and function and altered kinematic parameters of reaching movements. Feedback is an essential component of rehabilitation and auditory feedback of kinematic parameters may be a useful tool for rehabilitation of reaching movements at the impairment level. The aim of this study was to investigate the effect of 2 types of auditory feedback on the kinematics of reaching movements in hemiparetic stroke patients and to compare differences between patients with right (RHD and left hemisphere damage (LHD. Methods 10 healthy controls, 8 stroke patients with LHD and 8 with RHD were included. Patient groups had similar levels of upper limb function. Two types of auditory feedback (spatial and simple were developed and provided online during reaching movements to 9 targets in the workspace. Kinematics of the upper limb were recorded with an electromagnetic system. Kinematics were compared between groups (Mann Whitney test and the effect of auditory feedback on kinematics was tested within each patient group (Friedman test. Results In the patient groups, peak hand velocity was lower, the number of velocity peaks was higher and movements were more curved than in the healthy group. Despite having a similar clinical level, kinematics differed between LHD and RHD groups. Peak velocity was similar but LHD patients had fewer velocity peaks and less curved movements than RHD patients. The addition of auditory feedback improved the curvature index in patients with RHD and deteriorated peak velocity, the number of velocity peaks and curvature index in LHD patients. No difference between types of feedback was found in either patient group. Conclusion In stroke patients, side of lesion should be considered when examining arm reaching kinematics. Further studies are necessary to evaluate differences in responses to auditory feedback between patients with lesions in opposite

  15. The effects of different quantum feedback operator types on the parameter precision of detection efficiency in optimal quantum estimation

    Science.gov (United States)

    Ma, Shao-Qiang; Zhu, Han-Jie; Zhang, Guo-Feng

    2017-04-01

    The effects of different quantum feedback types on the estimation precision of the detection efficiency are studied. It is found that the precision can be more effective enhanced by a certain feedback type through comparing these feedbacks and the precision has a positive relation with detection efficiency for the optimal feedback when the system reach the state of dynamic balance. In addition, the bigger the proportion of |1> is the higher the precision is and we will not obtain any information about the parameter to be estimated if |0> is chosen as initial state for the feedback type λσz.

  16. How to Make Feedback More Effective? Qualitative Findings from Pilot Testing of an Audit and Feedback Report for Endoscopists

    Directory of Open Access Journals (Sweden)

    Fiona Webster

    2016-01-01

    Full Text Available Background. Audit and feedback (A/F reports are one of the few knowledge translation activities that can effect change in physician behavior. In this study, we pilot-tested an endoscopist A/F report to elicit opinions about the proposed report’s usability, acceptability and usefulness, and implications for knowledge translation. Methods. Semi-structured qualitative interviews were conducted with eleven endoscopists in Ontario, Canada. We tested an A/F report template comprising 9 validated, accepted colonoscopy quality indicators populated with simulated data. Interview transcripts were coded using techniques such as constant comparison and themes were identified inductively over several team meetings. Results. Four interrelated themes were identified: (1 overall perceptions of the A/F report; (2 accountability and consequences for poor performance; (3 motivation to change/improve skills; and (4 training for performance enhancement and available resources. The A/F report was well received; however, participants cited some possible threats to the report’s effectiveness including the perceived threat of loss of privileges or licensing and the potential for the data to be dismissed. Conclusions. Participants agreed that A/F has the potential to improve colonoscopy performance. However, in order to be effective in changing physician behavior, A/F must be thoughtfully implemented with attention to the potential concerns of its recipients.

  17. Effects of Concurrent and Delayed Visual Feedback on Motor Memory Consolidation.

    Science.gov (United States)

    Wang, Dangxiao; Li, Teng; Yang, Gaofeng; Zhang, Yuru

    2017-02-22

    In many domains, it's important to understand the ways in which humans learn and develop new motor skills effectively and efficiently. For example, in dental operations, the ability to apply a weak force with a required tolerance is a fundamental skill to ensure diagnostic and treatment outcome, but acquiring such a skill is a challenge for novices. In this paper, we focus on motor memory for producing normally applied force by a hand-held probe and we compare the effects of two feedback methods on motor memory consolidation. Fourteen participants were randomly assigned to two groups: a Concurrent Group and a Delayed Group. Participants in the Concurrent Group were trained to apply a target force with concurrent visual feedback, while those in the Delayed Group were trained with delayed visual feedback. The task included two phases: a Training/Testing Phase, and a Retention Phase. The results indicated that participants in the Delayed Group obtained more effective learning outcomes and better retention effects. These findings provide a new perspective to explore the relationship between feedback methods and the cognitive process of motor skill learning, and open a new way to train motor skill using more effective methods than the traditional concurrent feedback approaches.

  18. Stabilization using both noisy and noiseless feedback

    OpenAIRE

    Sahai, Anant

    2006-01-01

    When designing a distributed control system, the system designer has a choice in how to connect the different units through communication channels. In practice, noiseless and noisy channels may coexist. Using the standard toy example of scalar stabilization, this paper shows how a small amount of noiseless feedback can perform a ``supervisory'' role and thereby boost the effectiveness of noisy feedback.

  19. Effects of Person- and Process-Focused Feedback on Prosocial Behavior in Middle Childhood.

    Science.gov (United States)

    Dunsmore, Julie C

    2015-02-01

    Effects of person- and process-focused feedback, parental lay theories, and prosocial self-concept on children's prosocial behavior were investigated with 143 9- and 10-year-old children who participated in a single session. Parents reported entity (person-focused) and incremental (process-focused) beliefs related to prosocial behavior. Children completed measures of prosocial self-concept, then participated in a virtual online chat with child actors who asked for help with service projects. After completing the chat, children could assist with the service projects. In the first cohort, children were randomly assigned to receive person-focused, process-focused, or control feedback about sympathy. In the second cohort, with newly-recruited families, children received no feedback. When given process-focused feedback, children spent less time spent helping and worked on fewer service projects. When given no feedback, children spent less time helping when parents held incremental (process-focused) beliefs. Children with higher prosocial self-concept who received no feedback worked on more service projects.

  20. Biomechanical assessments of the effect of visual feedback on cycling for patients with stroke.

    Science.gov (United States)

    Lin, Sang-I; Lo, Chao-Chen; Lin, Pei-Yi; Chen, Jia-Jin J

    2012-08-01

    Stroke patients exhibit abnormal pattern in leg cycling exercise. The aim of this study was to investigate the effects of visual feedback on the control of cycling motion in stroke patients from kinesiological, kinematic and kinetic aspects. The cycling performance derived from cycling electromyography (EMG), cycling cadence, and torque of forty stroke subjects was evaluated under conditions with and without visual feedback of cycling cadence. Kinesiological indices, shape symmetry index (SSI) and area symmetry index (ASI) were extracted from EMG linear envelopes to evaluate the symmetry of muscle firing patterns during cycling. Roughness index (RI) was calculated from cycling cadence to represent cycling smoothness from kinematic aspects. Averaged cycling power (Pav), the product of cadence and torque, was used to represent force output. The rectus femoris EMG showed significantly greater ASI with visual feedback, however, the difference in SSI between the two conditions was not significant. For the biceps femoris, there was a significant decrease in SSI with visual feedback, while the ASI was not affected significantly by the task conditions. The cycling smoothness was better and the average power generated was larger when visual feedback was provided. This study found that the addition of visual feedback improved both neuromuscular control and overall performance. Such improvement is likely to be the result of better control of the rectus femoris muscle activation and coordination of both legs.

  1. An Effective Feedback Control Mechanism for DiffServ Architecture

    Institute of Scientific and Technical Information of China (English)

    王重钢; 隆克平; 杨健; 程时端

    2002-01-01

    As a scalable QoS (Quality of Service) architecture, DiffServ (Differentiated Service) mainly consists of two components: traffic conditioning at the edge of the DiffServ domain and simple packet forwarding inside the DiffServ domain. DiffServ has many advantages such as flexibility, scalability and simplicity. But when providing AF (Assured Forwarding)services, DiffServ has some problems such as unfairness among aggregated flows or among microflows belonging to an aggregated flow. In this paper, a feedback mechanism for AF aggregated flows is proposed to solve this problem. Simulation results show that this mechanism does improve the performance of DiffServ. First, it can improve the fairness among aggregated flows and make DiffServ more friendly toward TCP (Transmission Control Protocol) flows. Second,it can decrease the buffer requirements at the congested router and thus obtain lower delay and packet loss rate. Third, it also keeps almost the same link utility as in normal DiffServ.Finally, it is simple and easy to be implemented.

  2. Cycling in the Absence of Task-related Feedback: Effects on Pacing and Performance

    Directory of Open Access Journals (Sweden)

    Benjamin Smits

    2016-08-01

    Full Text Available Introduction. To achieve personal goals in exercise task completion, exercisers have to regulate, distribute and manage their effort. In endurance sports, it has become very commonplace for athletes to consult task-related feedback on external devices to do so. The aim of the present study was to explore the importance of the presence of this information by examining the influence of the absence of commonly available task-related feedback on effort distribution and performance in experienced endurance athletes.Methods. A 20-km cycling time trial was performed. 20 Participants from a homogenous cyclist population were appointed to a group that did not receive any feedback (NoF, or a group that could consult task-related feedback (i.e., speed, heart rate, power output, cadence, elapsed time and elapsed distance continuously during their trial (FF.Results. The distribution of power output (PO differed between groups. Most evident is the spurt at the end of the trial of FF, which was not incorporated by NoF. Nevertheless, no between-group differences were found in performance time (FF: 28.86 +/- 3.68 min vs. NoF: 30.95 +/- 2.77 min and mean PO controlled by body mass (FF: 3.61 +/- .60 W/kg vs. NoF: 3.43 +/- .38 W/kg. Also, no differences in rating of perceived exertion scores were found.Conclusion. The current study provides a first indication that prior knowledge of task demands together with reliance on bodily and environmental information can be sufficient for experienced athletes to come to comparable time trial performances. This questions the necessity of the presence of in-race instantaneous task-related feedback via external devices for maximising performance. Moreover, it seems that different pacing strategies emerge depending on sources of information available to experienced athletes.

  3. The feedback effect caused by bed load on a turbulent liquid flow

    CERN Document Server

    Franklin, Erick de Moraes; Rosa, Eugênio Spanó

    2016-01-01

    Experiments on the effects due solely to a mobile granular layer on a liquid flow are presented (feedback effect). Nonintrusive measurements were performed in a closed conduit channel of rectangular cross section where grains were transported as bed load by a turbulent water flow. The water velocity profiles were measured over fixed and mobile granular beds of same granulometry by Particle Image Velocimetry. The spatial resolution of the measurements allowed the experimental quantification of the feedback effect. The present findings are of importance for predicting the bed-load transport rate and the pressure drop in activities related to the conveyance of grains.

  4. A novel approach for generating flat optical frequency comb based on externally injected gain-switching distributed feedback semiconductor laser

    Science.gov (United States)

    Zhu, Huatao; Wang, Rong; Pu, Tao; Xiang, Peng; Zheng, Jilin; Fang, Tao

    2017-02-01

    In this paper, a novel approach for generating flat optical frequency comb (OFC) based on externally injected gain-switched distributed feedback (DFB) semiconductor laser is proposed and experimentally demonstrated. In the proposed system, the flatness, the number of OFC spectral lines, and the spectral line to background noise ratio can be tuned to their optimized values by adjusting the current of the modulation signal, the injection ratio and the detuning frequency. Since the frequency of the modulation signal decides the frequency spacing of the output spectral lines, OFC spectral lines of different spacing can be achieved. In the experiment, 10 spectral lines with 1.5 dB power variation are demonstrated to verify the proposed approach. In addition, the expansion of the spectral line is investigated.

  5. Hydrogen peroxide detection with quartz-enhanced photoacoustic spectroscopy using a distributed-feedback quantum cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Wei, E-mail: wr5@rice.edu; Jiang, Wenzhe; Tittel, Frank K. [Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, Texas 77005 (United States); Sanchez, Nancy P.; Griffin, Robert J. [Department of Civil and Environmental Engineering, Rice University, 6100 Main Street, Houston, Texas 77005 (United States); Patimisco, Pietro [Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, Texas 77005 (United States); Dipartimento Interateneo di Fisica, Università e Politecnico di Bari, Via Amendola 173, Bari 70126 (Italy); Spagnolo, Vincenzo [Dipartimento Interateneo di Fisica, Università e Politecnico di Bari, Via Amendola 173, Bari 70126 (Italy); Zah, Chung-en; Xie, Feng; Hughes, Lawrence C. [Corning Incorporated, Corning, New York 14831 (United States)

    2014-01-27

    A quartz-enhanced photoacoustic spectroscopy sensor system was developed for the sensitive detection of hydrogen peroxide (H{sub 2}O{sub 2}) using its absorption transitions in the v{sub 6} fundamental band at ∼7.73 μm. The recent availability of distributed-feedback quantum cascade lasers provides convenient access to a strong H{sub 2}O{sub 2} absorption line located at 1295.55 cm{sup −1}. Sensor calibration was performed by means of a water bubbler that generated titrated average H{sub 2}O{sub 2} vapor concentrations. A minimum detection limit of 12 parts per billion (ppb) corresponding to a normalized noise equivalent absorption coefficient of 4.6 × 10{sup −9} cm{sup −1}W/Hz{sup 1/2} was achieved with an averaging time of 100 s.

  6. Enhancing the Performance of Distributed Feedback Dye Lasers and Plasmonic V-grooves for Lab-on-a-chip Systems

    DEFF Research Database (Denmark)

    Smith, Cameron

    of the laser emission wavelength. We provide a framework for designing optimized DFB laser sensors comprising a thin TiO2 guiding layer. Regarding the second, plasmonic V-grooves offer a means to control the trade-off between e-field confinement and propagation length by varying the V-shape profile, opening......The ability to perform laboratory operations in compact systems is not only advantageous for the development of diagnostics tools and their production, but also provides unique opportunities to explore the natural world on the micro- and nanoscale. To this end, we focus on two optical schemes: 1......) polymer-based distributed feedback (DFB) dye lasers, and 2) plasmonic V-grooves. Regarding the first, DFB dye lasers are well suited to serve as compact, minimal analyte volume and highly sensitive refractive index sensors, where changes occurring in an analyte result in readily measurable shifts...

  7. A novel feedback control system – Controlling the material flow in deep drawing using distributed blank-holder force

    DEFF Research Database (Denmark)

    Endelt, Benny Ørtoft; Tommerup, Søren; Danckert, Joachim

    2013-01-01

    on a deep drawing operation where the objective was to control material flow throughout the part using only spatial information regarding flange draw-in. The control system controls both the magnitude and distribution of the blank-holder force. The methodology proved stable and flexible with respect......The performance of a feedback control system is often limited by the quality of the model on which it is based, and often the controller design is based on trial and error due to insufficient modeling capabilities. A framework is proposed where the controller design is based on classical state...... space control theory and time series. The system plant has been modeled using non-linear finite element and the gain factors for the control loop were identified by solving the optimal control problem using a non-linear least square optimization algorithm. The proposed design method has been applied...

  8. Comparison of two kinds of active layers for high-power narrow-stripe distributed feedback laser diodes

    Institute of Scientific and Technical Information of China (English)

    Fu Sheng-Hui; Song Guo-Feng; Chen Liang-Hui

    2007-01-01

    Usually GaAs/AlGaAs is utilized as an active layer material in laser diodes operating in the spectral range of 800-850 nm.In this work,in addition to a traditional unstrained GaAs/AlGaAs distributed feedback(DFB) laser diode,a compressively strained InGaAlAs/AlGaAs DFB laser diode is numerically investigated in characteristic.The simulation results show that the compressively strained DFB laser diode has a lower transparency carrier density,higher gain,lower Auger recombination rate.and higher stimulated recombination rate.which lead to better a device performance.than the traditional unstrained GaAs/AlGaAs DFB laser diode.

  9. Holistic face perception in young and older adults: effects of feedback and attentional demand.

    Science.gov (United States)

    Meinhardt-Injac, Bozana; Persike, Malte; Meinhardt, Günter

    2014-01-01

    Evidence exists for age-related decline in face cognition ability. However, the extents to which attentional demand and flexibility to adapt viewing strategies contribute to age-related decline in face cognition tests is poorly understood. Here, we studied holistic face perception in older (age range 65-78 years, mean age 69.9) and young adults (age range 20-32 years, mean age 23.1) using the complete design for a sequential study-test composite face task (Richler et al., 2008b). Attentional demand was varied using trials that required participants to attend to both face halves and to redirect attention to one face half during the test (high attentional demand), and trials that allowed participants to keep a pre-adjusted focus (low attentional demand). We also varied viewing time and provided trial-by-trial feedback or no feedback. We observed strong composite effects, which were larger for the elderly in all conditions, independent of viewing time. Composite effects were smaller for low attentional demand, and larger for high attentional demand. No age-related differences were found in this respect. Feedback also reduced the composite effects in both age groups. Young adults could benefit from feedback in conditions with low and high attentional demands. Older adults performed better with feedback only in trials with low attentional demand. When attentional demand was high, older adults could no longer use the feedback signal, and performed worse with feedback than without. These findings suggest that older adults tend to use a global focus for faces, albeit piecemeal analysis is required for the task, and have difficulties adapting their viewing strategies when task demands are high. These results are consistent with the idea that elderly rely more on holistic strategies as a means to reduce perceptual and cognitive load when processing resources are limited (Konar et al., 2013).

  10. Effects of computer-based immediate feedback on foreign language listening comprehension and test-associated anxiety.

    Science.gov (United States)

    Lee, Shu-Ping; Su, Hui-Kai; Lee, Shin-Da

    2012-06-01

    This study investigated the effects of immediate feedback on computer-based foreign language listening comprehension tests and on intrapersonal test-associated anxiety in 72 English major college students at a Taiwanese University. Foreign language listening comprehension of computer-based tests designed by MOODLE, a dynamic e-learning environment, with or without immediate feedback together with the state-trait anxiety inventory (STAI) were tested and repeated after one week. The analysis indicated that immediate feedback during testing caused significantly higher anxiety and resulted in significantly higher listening scores than in the control group, which had no feedback. However, repeated feedback did not affect the test anxiety and listening scores. Computer-based immediate feedback did not lower debilitating effects of anxiety but enhanced students' intrapersonal eustress-like anxiety and probably improved their attention during listening tests. Computer-based tests with immediate feedback might help foreign language learners to increase attention in foreign language listening comprehension.

  11. Second language feedback abolishes the "hot hand" effect during even-probability gambling.

    Science.gov (United States)

    Gao, Shan; Zika, Ondrej; Rogers, Robert D; Thierry, Guillaume

    2015-04-15

    Research into language-emotion interactions has revealed intriguing cognitive inhibition effects by emotionally negative words in bilinguals. Here, we turn to the domain of human risk taking and show that the experience of positive recency in games of chance-the "hot hand" effect-is diminished when game outcomes are provided in a second language rather than the native language. We engaged late Chinese-English bilinguals with "play" or "leave" decisions upon presentation of equal-odds bets while manipulating language of feedback and outcome value. When positive game outcomes were presented in their second language, English, participants subsequently took significantly fewer gambles and responded slower compared with the trials in which equivalent feedback was provided in Chinese, their native language. Positive feedback was identified as driving the cross-language difference in preference for risk over certainty: feedback for previous winning outcomes presented in Chinese increased subsequent risk taking, whereas in the English context no such effect was observed. Complementing this behavioral effect, event-related brain potentials elicited by feedback words showed an amplified response to Chinese relative to English in the feedback-related negativity window, indicating a stronger impact in the native than in the second language. We also observed a main effect of language on P300 amplitude and found it correlated with the cross-language difference in risk selections, suggesting that the greater the difference in attention between languages, the greater the difference in risk-taking behavior. These results provide evidence that the hot hand effect is at least attenuated when an individual operates in a non-native language.

  12. The Effect of Direct and Indirect Corrective Feedback on Students’ Spelling Errors

    Directory of Open Access Journals (Sweden)

    Baleghizadeh Sasan

    2011-04-01

    Full Text Available

    The study presented here is an attempt to examine the role of indirect feedback in promoting junior high school students’ spelling accuracy in English. It compares the effect of direct feedback with indirect feedback on students’ written work dictated by their teacher from their textbooks. Two classes were selected from the Zanjanrood District in Iran. Forty-four male students in two groups, one from School A (the direct feedback group and the other from School B (the indirect feedback group were treated differently regarding their spelling errors for six weeks. The results obtained revealed that indirect feedback is a more effective tool than direct feedback in rectifying students’ spelling errors.

    El estudio que aquí se reporta busca examinar el papel de la retroalimentación indirecta, en la promoción de la precisión en la escritura en inglés, de estudiantes de educación secundaria. Se comparan los efectos de la retroalimentación directa e indirecta en los trabajos escritos de los estudiantes, provenientes de los libros de texto y de dictados hechos por el profesor. Se seleccionaron dos grupos del Distrito Zanjanrood en Irán a los que se les dio, durante seis semanas, un tratamiento distinto respecto a sus errores de ortografía. En total, eran cuarenta y cinco estudiantes de sexo masculino, distribuidos en dos grupos: uno de la Escuela A (el grupo que recibió retroalimentación directa y otro de la de la Escuela B (el grupo que recibió retroalimentación indirecta. Los resultados mostraron que la retroalimentación indirecta es una herramienta más efectiva que la directa, cuando se trata de rectificar los errores de ortografía de los estudiantes.

  13. Midterm Peer Feedback in Problem-Based Learning Groups: The Effect on Individual Contributions and Achievement

    Science.gov (United States)

    Kamp, Rachelle J. A.; van Berkel, Henk J. M.; Popeijus, Herman E.; Leppink, Jimmie; Schmidt, Henk G.; Dolmans, Diana H. J. M.

    2014-01-01

    Even though peer process feedback is an often used tool to enhance the effectiveness of collaborative learning environments like PBL, the conditions under which it is best facilitated still need to be investigated. Therefore, this study investigated the effects of individual versus shared reflection and goal setting on students' individual…

  14. The Effects of Training, Feedback, and Participant Involvement in Behavioral Safety Observations on Office Ergonomic Behavior

    Science.gov (United States)

    Sasson, Joseph R.; Austin, John

    2005-01-01

    Eleven computer terminal operators participated in an experiment that assessed effects of several interventions aimed at increasing safe ergonomic performance. All participants received ergonomics training and performance feedback while six of them collected observations of safe behavior among the remaining five participants. Effects of…

  15. Midterm Peer Feedback in Problem-Based Learning Groups: The Effect on Individual Contributions and Achievement

    Science.gov (United States)

    Kamp, Rachelle J. A.; van Berkel, Henk J. M.; Popeijus, Herman E.; Leppink, Jimmie; Schmidt, Henk G.; Dolmans, Diana H. J. M.

    2014-01-01

    Even though peer process feedback is an often used tool to enhance the effectiveness of collaborative learning environments like PBL, the conditions under which it is best facilitated still need to be investigated. Therefore, this study investigated the effects of individual versus shared reflection and goal setting on students' individual…

  16. Bubbling effect in the electro-optic delayed feedback oscillator coupled network

    Science.gov (United States)

    Liu, Lingfeng; Lin, Jun; Miao, Suoxia

    2017-03-01

    Synchronization in the optical systems coupled network always suffers from bubbling events. In this paper, we numerically investigate the statistical properties of the synchronization characteristics and bubbling effects in the electro-optic delayed feedback oscillator coupled network with different coupling strength, delay time and gain coefficient. Furthermore, we compare our results with the synchronization properties of semiconductor laser (SL) coupled network, which indicates that the electro-optic delayed feedback oscillator can be better to suppress the bubbling effects in the synchronization of coupled network under the same conditions.

  17. Effects of Partial Absence of Visual Feedback Information on Gait Symmetry.

    Science.gov (United States)

    Kim, Seung-Jae; Kayitesi, Marie Aimee; Chan, Amy; Graham, Kimberli

    2017-03-14

    The incorporation of real-time visual feedback during gait rehabilitation can improve the efficacy of training. Our prior work demonstrated that the imposed distortion of simple visual feedback information of step lengths entails an unintentional adaptive process in the subjects' spatial gait pattern, thereby suggesting the important role of implicit learning in the context of gait rehabilitation that employs visual feedback. The purpose of this study was to investigate whether the removal of a portion of visual feedback information-after it had initially been provided-had any impact on gait symmetry. Eighteen healthy subjects walked on a treadmill for 10-min periods at their preferred walking speed and at a slower walking speed (1.3 mph) during the experimental trials, in which two simple vertical bars corresponding to subject's right and left step length were displayed on a computer screen. Halfway through the trial, one of the bars was removed from the visual feedback via random selection. Subjects were instructed to continually walk normally and also look at the visual feedback until the trials were completed. The changes in step length symmetry ratio were computed and analyzed. We found that displaying only one side of visual feedback influenced subjects to spontaneously modulate gait symmetry away from the baseline, and also that the amount of modulated gait symmetry slightly increased when their walking speed decreased. The changes in gait symmetry occurred by producing either longer right steps produced than left steps or vice versa, but we were unable to find any correlation between side of removal (right or left side) and the different types of trend in response. This warrants further investigation in a study with a larger population. Nonetheless, the results of this study demonstrated the effect of partial absence of visual feedback on changes in step symmetry, and that the perturbation of visual information caused implicit (unintentional) motor

  18. Persuasive performance feedback: the effect of framing on self-efficacy.

    Science.gov (United States)

    Choe, Eun Kyoung; Lee, Bongshin; Munson, Sean; Pratt, Wanda; Kientz, Julie A

    2013-01-01

    Self-monitoring technologies have proliferated in recent years as they offer excellent potential for promoting healthy behaviors. Although these technologies have varied ways of providing real-time feedback on a user's current progress, we have a dearth of knowledge of the framing effects on the performance feedback these tools provide. With an aim to create influential, persuasive performance feedback that will nudge people toward healthy behaviors, we conducted an online experiment to investigate the effect of framing on an individual's self-efficacy. We identified 3 different types of framing that can be applicable in presenting performance feedback: (1) the valence of performance (remaining vs. achieved framing), (2) presentation type (text-only vs. text with visual), and (3) data unit (raw vs. percentage). Results show that the achieved framing could lead to an increased perception of individual's performance capabilities. This work provides empirical guidance for creating persuasive performance feedback, thereby helping people designing self-monitoring technologies to promote healthy behaviors.

  19. Steep switching characteristics of single-gated feedback field-effect transistors

    Science.gov (United States)

    Kim, Minsuk; Kim, Yoonjoong; Lim, Doohyeok; Woo, Sola; Cho, Kyoungah; Kim, Sangsig

    2017-02-01

    In this study, we propose newly designed feedback field-effect transistors that utilize the positive feedback of charge carriers in single-gated silicon channels to achieve steep switching behaviors. The band diagram, I-V characteristics, subthreshold swing, and on/off current ratio are analyzed using a commercial device simulator. Our proposed feedback field-effect transistors exhibit subthreshold swings of less than 0.1 mV dec-1, an on/off current ratio of approximately 1011, and an on-current of approximately 10-4 A at room temperature, demonstrating that the switching characteristics are superior to those of other silicon-based devices. In addition, the device parameters that affect the device performance, hysteresis characteristics, and temperature-dependent device characteristics are discussed in detail.

  20. Five Steps to Providing Effective Feedback in the Clinical Setting: A New Approach to Promote Teamwork and Collaboration.

    Science.gov (United States)

    Motley, Cindy L; Dolansky, Mary A

    2015-07-01

    Feedback is a major component of clinical education. Feedback reinforces or modifies behavior and helps learners to validate knowledge and feel motivated to learn. Traditionally, feedback is used by clinical educators who observe learners' behavior and provide expert direction. Teamwork and collaboration is one of the six Quality and Safety Education for Nurses core competencies developed for prelicensure and graduate nurses. These skills are important in the current complex health care environment. On the basis of the literature and prior experience, a new approach for clinical educators is using feedback to teach teamwork and collaboration skills. Five steps educators can take to provide effective feedback in the clinical setting are to (a) create a culture of feedback, (b) use structured communication tools, (c) encourage dialogue, (d) acknowledge the human factor, and (e) embrace a leadership role. This new approach enhances feedback and teaches teamwork and collaboration. Copyright 2015, SLACK Incorporated.

  1. Collaborative and Bidirectional Feedback Between Students and Clinical Preceptors: Promoting Effective Communication Skills on Health Care Teams.

    Science.gov (United States)

    Myers, Kara; Chou, Calvin L

    2016-11-01

    Current literature on feedback suggests that clinical preceptors lead feedback conversations that are primarily unidirectional, from preceptor to student. While this approach may promote clinical competency, it does not actively develop students' competency in facilitating feedback discussions and providing feedback across power differentials (ie, from student to preceptor). This latter competency warrants particular attention given its fundamental role in effective health care team communication and its related influence on patient safety. Reframing the feedback process as collaborative and bidirectional, where both preceptors and students provide and receive feedback, maximizes opportunities for role modeling and skills practice in the context of a supportive relationship, thereby enhancing team preparedness. We describe an initiative to introduce these fundamental skills of collaborative, bidirectional feedback in the nurse-midwifery education program at the University of California, San Francisco. © 2016 by the American College of Nurse-Midwives.

  2. The Effects of Mirror Feedback during Target Directed Movements on Ipsilateral Corticospinal Excitability

    Science.gov (United States)

    Yarossi, Mathew; Manuweera, Thushini; Adamovich, Sergei V.; Tunik, Eugene

    2017-01-01

    Mirror visual feedback (MVF) training is a promising technique to promote activation in the lesioned hemisphere following stroke, and aid recovery. However, current outcomes of MVF training are mixed, in part, due to variability in the task undertaken during MVF. The present study investigated the hypothesis that movements directed toward visual targets may enhance MVF modulation of motor cortex (M1) excitability ipsilateral to the trained hand compared to movements without visual targets. Ten healthy subjects participated in a 2 × 2 factorial design in which feedback (veridical, mirror) and presence of a visual target (target present, target absent) for a right index-finger flexion task were systematically manipulated in a virtual environment. To measure M1 excitability, transcranial magnetic stimulation (TMS) was applied to the hemisphere ipsilateral to the trained hand to elicit motor evoked potentials (MEPs) in the untrained first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles at rest prior to and following each of four 2-min blocks of 30 movements (B1–B4). Targeted movement kinematics without visual feedback was measured before and after training to assess learning and transfer. FDI MEPs were decreased in B1 and B2 when movements were made with veridical feedback and visual targets were absent. FDI MEPs were decreased in B2 and B3 when movements were made with mirror feedback and visual targets were absent. FDI MEPs were increased in B3 when movements were made with mirror feedback and visual targets were present. Significant MEP changes were not present for the uninvolved ADM, suggesting a task-specific effect. Analysis of kinematics revealed learning occurred in visual target-directed conditions, but transfer was not sensitive to mirror feedback. Results are discussed with respect to current theoretical mechanisms underlying MVF-induced changes in ipsilateral excitability. PMID:28553218

  3. The Effects of Mirror Feedback during Target Directed Movements on Ipsilateral Corticospinal Excitability

    Directory of Open Access Journals (Sweden)

    Mathew Yarossi

    2017-05-01

    Full Text Available Mirror visual feedback (MVF training is a promising technique to promote activation in the lesioned hemisphere following stroke, and aid recovery. However, current outcomes of MVF training are mixed, in part, due to variability in the task undertaken during MVF. The present study investigated the hypothesis that movements directed toward visual targets may enhance MVF modulation of motor cortex (M1 excitability ipsilateral to the trained hand compared to movements without visual targets. Ten healthy subjects participated in a 2 × 2 factorial design in which feedback (veridical, mirror and presence of a visual target (target present, target absent for a right index-finger flexion task were systematically manipulated in a virtual environment. To measure M1 excitability, transcranial magnetic stimulation (TMS was applied to the hemisphere ipsilateral to the trained hand to elicit motor evoked potentials (MEPs in the untrained first dorsal interosseous (FDI and abductor digiti minimi (ADM muscles at rest prior to and following each of four 2-min blocks of 30 movements (B1–B4. Targeted movement kinematics without visual feedback was measured before and after training to assess learning and transfer. FDI MEPs were decreased in B1 and B2 when movements were made with veridical feedback and visual targets were absent. FDI MEPs were decreased in B2 and B3 when movements were made with mirror feedback and visual targets were absent. FDI MEPs were increased in B3 when movements were made with mirror feedback and visual targets were present. Significant MEP changes were not present for the uninvolved ADM, suggesting a task-specific effect. Analysis of kinematics revealed learning occurred in visual target-directed conditions, but transfer was not sensitive to mirror feedback. Results are discussed with respect to current theoretical mechanisms underlying MVF-induced changes in ipsilateral excitability.

  4. Effect of feedback on delaying deterioration in quality of compressions during 2 minutes of continuous chest compressions: a randomized manikin study investigating performance with and without feedback

    Directory of Open Access Journals (Sweden)

    Lyngeraa Tobias

    2012-02-01

    Full Text Available Abstract Background Good quality basic life support (BLS improves outcome following cardiac arrest. As BLS performance deteriorates over time we performed a parallel group, superiority study to investigate the effect of feedback on quality of chest compression with the hypothesis that feedback delays deterioration of quality of compressions. Methods Participants attending a national one-day conference on cardiac arrest and CPR in Denmark were randomized to perform single-rescuer BLS with (n = 26 or without verbal and visual feedback (n = 28 on a manikin using a ZOLL AED plus. Data were analyzed using Rescuenet Code Review. Blinding of participants was not possible, but allocation concealment was performed. Primary outcome was the proportion of delivered compressions within target depth compared over a 2-minute period within the groups and between the groups. Secondary outcome was the proportion of delivered compressions within target rate compared over a 2-minute period within the groups and between the groups. Performance variables for 30-second intervals were analyzed and compared. Results 24 (92% and 23 (82% had CPR experience in the group with and without feedback respectively. 14 (54% were CPR instructors in the feedback group and 18 (64% in the group without feedback. Data from 26 and 28 participants were analyzed respectively. Although median values for proportion of delivered compressions within target depth were higher in the feedback group (0-30 s: 54.0%; 30-60 s: 88.0%; 60-90 s: 72.6%; 90-120 s: 87.0%, no significant difference was found when compared to without feedback (0-30 s: 19.6%; 30-60 s: 33.1%; 60-90 s: 44.5%; 90-120 s: 32.7% and no significant deteriorations over time were found within the groups. In the feedback group a significant improvement was found in the proportion of delivered compressions below target depth when the subsequent intervals were compared to the first 30 seconds (0-30 s: 3.9%; 30-60 s: 0.0%; 60-90 s: 0

  5. Simulation of bulk aerosol direct radiative effects and its climatic feedbacks in South Africa using RegCM4

    Science.gov (United States)

    Tesfaye, M.; Botai, J.; Sivakumar, V.; Mengistu Tsidu, G.; Rautenbach, C. J. deW.; Moja, Shadung J.

    2016-05-01

    In this study, 12 year runs of the Regional Climate Model (RegCM4) have been used to analyze the bulk aerosol radiative effects and its climatic feedbacks in South Africa. Due to the geographical locations where the aerosol potential source regions are situated and the regional dynamics, the South African aerosol spatial-distribution has a unique feature. Across the west and southwest areas, desert dust particles are dominant. However, sulfate and carbonaceous aerosols are primarily distributed over the east and northern regions of the country. Analysis of the Radiative Effects (RE) shows that in South Africa the bulk aerosols play a role in reducing the net radiation absorbed by the surface via enhancing the net radiative heating in the atmosphere. Hence, across all seasons, the bulk aerosol-radiation-climate interaction induced statistically significant positive feedback on the net atmospheric heating rate. Over the western and central parts of South Africa, the overall radiative feedbacks of bulk aerosol predominantly induces statistically significant Cloud Cover (CC) enhancements. Whereas, over the east and southeast coastal areas, it induces minimum reductions in CC. The CC enhancement and RE of aerosols jointly induce radiative cooling at the surface which in turn results in the reduction of Surface Temperature (ST: up to -1 K) and Surface Sensible Heat Flux (SSHF: up to -24 W/m2). The ST and SSHF decreases cause a weakening of the convectively driven turbulences and surface buoyancy fluxes which lead to the reduction of the boundary layer height, surface pressure enhancement and dynamical changes. Throughout the year, the maximum values of direct and semi-direct effects of bulk aerosol were found in areas of South Africa which are dominated by desert dust particles. This signals the need for a strategic regional plan on how to reduce the dust production and monitoring of the dust dispersion as well as it initiate the need of further research on different

  6. The Effects of Feedback Conditions and Practice on Typing Performance

    Science.gov (United States)

    Blixt, Sonya L.

    1977-01-01

    A report of an experiment which attempted to motivate students in straight-copy typing and the effects of the conditions upon typing speed and accuracy. The effects of the conditions did not prove to be significant. (HD)

  7. A RCT evaluating the effectiveness and cost-effectiveness of academic detailing versus postal prescribing feedback in changing GP antibiotic prescribing.

    LENUS (Irish Health Repository)

    Naughton, Corina

    2009-10-01

    The aim of this study is to evaluate the effectiveness of academic detailing (AD) plus postal prescribing feedback versus postal prescribing feedback alone in reducing: (i) the overall rate of antibiotic; and (ii) proportion of second-line antibiotic prescribing. In addition, the cost-effectiveness of an outreach prescriber adviser service versus a postal prescribing feedback service was evaluated.

  8. Rateless feedback codes

    DEFF Research Database (Denmark)

    Sørensen, Jesper Hemming; Koike-Akino, Toshiaki; Orlik, Philip

    2012-01-01

    This paper proposes a concept called rateless feedback coding. We redesign the existing LT and Raptor codes, by introducing new degree distributions for the case when a few feedback opportunities are available. We show that incorporating feedback to LT codes can significantly decrease both...... the coding overhead and the encoding/decoding complexity. Moreover, we show that, at the price of a slight increase in the coding overhead, linear complexity is achieved with Raptor feedback coding....

  9. Training symmetry of weight distribution after stroke: a randomized controlled pilot study comparing task-related reach, Bobath and feedback training approaches.

    Science.gov (United States)

    Mudie, M H; Winzeler-Mercay, U; Radwan, S; Lee, L

    2002-09-01

    To determine (1) the most effective of three treatment approaches to retrain seated weight distribution long-term after stroke and (2) whether improvements could be generalized to weight distribution in standing. Inpatient rehabilitation unit. Forty asymmetrical acute stroke subjects were randomly allocated to one of four groups in this pilot study. Changes in weight distribution were compared between the 10 subjects of each of three treatment groups (task-specific reach, Bobath, or Balance Performance Monitor [BPM] feedback training) and a no specific treatment control group. One week of measurement only was followed by two weeks of daily training sessions with the treatment to which the subject was randomly allocated. Measurements were performed using the BPM daily before treatment sessions, two weeks after cessation of treatment and 12 weeks post study. Weight distribution was calculated in terms of mean balance (percentage of total body weight) or the mean of 300 balance points over a 30-s data run. In the short term, the Bobath approach was the most effective treatment for retraining sitting symmetry after stroke (p = 0.004). Training with the BPM and no training were also significant (p = 0.038 and p = 0.035 respectively) and task-specific reach training failed to reach significance (p = 0.26). At 12 weeks post study 83% of the BPM training group, 38% of the task-specific reach group, 29% of the Bobath group and 0% of the untrained group were found to be distributing their weight to both sides. Some generalization of symmetry training in sitting to standing was noted in the BPM training group which appeared to persist long term. Results should be treated with caution due to the small group sizes. However, these preliminary findings suggest that it might be possible to restore postural symmetry in sitting in the early stages of rehabilitation with therapy that focuses on creating an awareness of body position.

  10. The Effects of Anticipated Negative Feedback on Psychological States Among Narcissists

    Directory of Open Access Journals (Sweden)

    Akiko Matsuo

    2016-05-01

    Full Text Available Although narcissism has long been researched in relation to anger, previous research examined narcissistic anger toward negative feedback that had already occurred. In this study, we investigated the effects of anticipation of evaluation (present vs. absent and negative feedback (present vs. absent, using a creativity task paradigm, on state anger scores among 231 U.S. undergraduates (76% White, 60% women. We also measured undergraduates’ narcissistic tendencies and impressions of the creativity task. Multiple regression analyses revealed a significant interaction between narcissism and negative feedback on total anger scores, with narcissists responding with more anger than non-narcissists in the condition of negative feedback. We also found a significant two-way interaction between narcissism and anticipation of evaluation on total enjoyment scores. Anticipation of feedback inhibited narcissist-prone individuals from enjoying the task in the anticipation condition, but this pattern was not present in the no-anticipation condition. Implications and recommendations to better understand the nature of narcissism are discussed.

  11. Effect of Training and Level of External Auditory Feedback on the Singing Voice: Pitch Inaccuracy.

    Science.gov (United States)

    Bottalico, Pasquale; Graetzer, Simone; Hunter, Eric J

    2017-01-01

    One of the most important aspects of singing is the control of fundamental frequency. The effects on pitch inaccuracy, defined as the distance in cents in equally tempered tuning between the reference note and the sung note, of the following conditions were evaluated: (1) level of external feedback, (2) tempo (slow or fast), (3) articulation (legato or staccato), (4) tessitura (low, medium, or high), and (5) semi-phrase direction (ascending or descending). The subjects were 10 nonprofessional singers and 10 classically trained professional or semi-professional singers (10 men and 10 women). Subjects sang one octave and a fifth arpeggi with three different levels of external auditory feedback, two tempi, and two articulations (legato or staccato). It was observed that inaccuracy was greatest in the descending semi-phrase arpeggi produced at a fast tempo and with a staccato articulation, especially for nonprofessional singers. The magnitude of inaccuracy was also relatively large in the high tessitura relative to the low and the medium tessitura for such singers. Contrary to predictions, when external auditory feedback was strongly attenuated by the hearing protectors, nonprofessional singers showed greater pitch accuracy than in the other external feedback conditions. This finding indicates the importance of internal auditory feedback in pitch control. With an increase in training, the singer's pitch inaccuracy decreases. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  12. Effects of acoustic feedback training in elite-standard Para-Rowing.

    Science.gov (United States)

    Schaffert, Nina; Mattes, Klaus

    2015-01-01

    Assessment and feedback devices have been regularly used in technique training in high-performance sports. Biomechanical analysis is mainly visually based and so can exclude athletes with visual impairments. The aim of this study was to examine the effects of auditory feedback on mean boat speed during on-water training of visually impaired athletes. The German National Para-Rowing team (six athletes, mean ± s, age 34.8 ± 10.6 years, body mass 76.5 ± 13.5 kg, stature 179.3 ± 8.6 cm) participated in the study. Kinematics included boat acceleration and distance travelled, collected with Sofirow at two intensities of training. The boat acceleration-time traces were converted online into acoustic feedback and presented via speakers during rowing (sections with and without alternately). Repeated-measures within-participant factorial ANOVA showed greater boat speed with acoustic feedback than baseline (0.08 ± 0.01 m·s(-1)). The time structure of rowing cycles was improved (extended time of positive acceleration). Questioning of athletes showed acoustic feedback to be a supportive training aid as it provided important functional information about the boat motion independent of vision. It gave access for visually impaired athletes to biomechanical analysis via auditory information. The concept for adaptive athletes has been successfully integrated into the preparation for the Para-Rowing World Championships and Paralympics.

  13. Perceptions of teachers' general and informational feedback and intrinsic motivation in physical education: two-year effects.

    Science.gov (United States)

    Koka, Andre; Hein, Vello

    2006-10-01

    Relative change or stability of perceived positive general feedback and perceived informational feedback and their influence on students' intrinsic motivation in physical education over two years were examined. 302 students, ages 11 to 15 years, responded to the Perception of Teacher's Feedback questionnaire. Two years later, these students filled out the questionnaire again, along with a modified version of the Sport Motivation Scale. Analysis showed that both types of perceived feedback exhibited moderate stability over the two years. Perceived positive general feedback demonstrated a significant direct effect on students' intrinsic motivation measured concurrently in physical education. Further, fixing to zero the effect of perceived positive general feedback on intrinsic motivation measured concurrently, an effect emerged over the two years.

  14. Feedback first: the surprisingly weak effects of magnetic fields, viscosity, conduction, and metal diffusion on galaxy formation

    CERN Document Server

    Su, Kung-Yi; Hayward, Christopher C; Faucher-Giguere, Claude-Andre; Keres, Dusan; Ma, Xiangcheng; Robles, Victor H

    2016-01-01

    Using high-resolution simulations with explicit treatment of stellar feedback physics based on the FIRE (Feedback in Realistic Environments) project, we study how galaxy formation and the interstellar medium (ISM) are affected by magnetic fields, anisotropic Spitzer-Braginskii conduction and viscosity, and sub-grid turbulent metal diffusion. We consider controlled simulations of isolated (non-cosmological) galaxies but also a limited set of cosmological "zoom-in" simulations. Although simulations have shown significant effects from these physics with weak or absent stellar feedback, the effects are much weaker than those of stellar feedback when the latter is modeled explicitly. The additional physics have no systematic effect on galactic star formation rates (SFRs). In contrast, removing stellar feedback leads to SFRs being over-predicted by factors of $\\sim 10 -100$. Without feedback, neither galactic winds nor volume filling hot-phase gas exist, and discs tend to runaway collapse to ultra-thin scale-height...

  15. ELECTRE I Based Relevance Decision-Makers Feedback to the Location Selection of Distribution Centers

    Directory of Open Access Journals (Sweden)

    Maroi Agrebi

    2017-01-01

    Full Text Available The location selection of distribution centers is one of the important strategies to optimize the logistics system. To solve this problem, under certain environment, this paper presents a new multicriteria decision-making method based on ELECTRE I. The proposed method helps decision-makers to select the best location from a given set of locations for implementing. After having identified decision-makers, the criteria, and the set of locations, the factors influencing the selection are analyzed in order to identify the best location. A sensitivity analysis is then performed to determine the influence of criteria weights on the selection decision. The strength of the proposed method is to incorporate decision-makers’ preferences into the decision-making process. In addition, the proposed method considers both quantitative and qualitative criteria. Finally, the selected solution is validated by both tests of concordance and discordance simultaneously. A case study is provided to illustrate the proposed method.

  16. The Effect Of Different Corrective Feedback Methods on the Outcome and Self Confidence of Young Athletes

    Science.gov (United States)

    Tzetzis, George; Votsis, Evandros; Kourtessis, Thomas

    2008-01-01

    This experiment investigated the effects of three corrective feedback methods, using different combinations of correction, or error cues and positive feedback for learning two badminton skills with different difficulty (forehand clear - low difficulty, backhand clear - high difficulty). Outcome and self-confidence scores were used as dependent variables. The 48 participants were randomly assigned into four groups. Group A received correction cues and positive feedback. Group B received cues on errors of execution. Group C received positive feedback, correction cues and error cues. Group D was the control group. A pre, post and a retention test was conducted. A three way analysis of variance ANOVA (4 groups X 2 task difficulty X 3 measures) with repeated measures on the last factor revealed significant interactions for each depended variable. All the corrective feedback methods groups, increased their outcome scores over time for the easy skill, but only groups A and C for the difficult skill. Groups A and B had significantly better outcome scores than group C and the control group for the easy skill on the retention test. However, for the difficult skill, group C was better than groups A, B and D. The self confidence scores of groups A and C improved over time for the easy skill but not for group B and D. Again, for the difficult skill, only group C improved over time. Finally a regression analysis depicted that the improvement in performance predicted a proportion of the improvement in self confidence for both the easy and the difficult skill. It was concluded that when young athletes are taught skills of different difficulty, different type of instruction, might be more appropriate in order to improve outcome and self confidence. A more integrated approach on teaching will assist coaches or physical education teachers to be more efficient and effective. Key pointsThe type of the skill is a critical factor in determining the effectiveness of the feedback types

  17. The effect of feedback by SMS-text messages and email on household electricity consumption

    DEFF Research Database (Denmark)

    Gleerup, Maria; Larsen, Anders; Leth-Petersen, Søren

    2010-01-01

    This paper analyzes the effect of supplying feedback by text messages (SMS) and email about electricity consumption on the level of total household electricity consumption. An experiment was conducted in which 1,452 households were randomly allocated to three experimental groups and two control....... Results suggest that email and SMS messaging that communicated timely information about a household's 'exceptional' consumption periods (e.g. highest week of electricity use in past quarter) produced average reductions in total annual electricity use of about 3%. The feedback technology is cheap...

  18. The effects of different quantum feedback types on the tightness of the variance-based uncertainty

    Science.gov (United States)

    Zheng, Xiao; Zhang, Guo-Feng

    2017-03-01

    The effect of the quantum feedback on the tightness of the variance-based uncertainty, the possibility of using quantum feedback to prepare the state with a better tightness, and the relationship between the tightness of the uncertainty and the mixedness of the system are studied. It is found that the tightness of Schrodinger-Robertson uncertainty (SUR) relation has a strict liner relationship with the mixedness of the system. As for the Robertson uncertainty relation (RUR), we find that the tightness can be enhanced by tuning the feedback at the beginning of the evolution. In addition, we deduce that the tightness of RUR has an inverse relationship with the mixedness and the relationship turns into a strict linear one when the system reach the steady state.

  19. Effects of time-delayed feedback on the properties of self-sustained oscillators

    Science.gov (United States)

    Risau-Gusman, S.

    2016-10-01

    Most self-sustained oscillations in biological systems and in technical applications are based on a feedback loop, and it is usually important to know how they will react when an external oscillatory force is applied. Here we investigate the effects that the introduction of a time delay in the feedback can have in the entrainment properties of self-sustained oscillators. To do this, we derive analytic expressions for the periodic trajectories and their asymptotic stability, for a generic external oscillatory force. This allows us to show that, for large quality factors, the resonance frequency does not depend on the feedback delay. When the external force is harmonic, it is shown that the largest entrainment range does not correspond to the time delay that gives the maximal response of the unforced oscillator. In fact, that delay gives the shortest entrainment range.

  20. Measurement of stress-induced birefringence in glasses based on reflective laser feedback effect

    Science.gov (United States)

    Haisha, Niu; YanXiong, Niu; Jiyang, Li

    2017-02-01

    A glass birefringence measurement system utilizing the reflective laser feedback (RLF) effect is presented. The measurement principle is analyzed based on the equivalent cavity of a Fabry-Perot interferometer, and the experiments are conducted with a piece of quartz glass with applied extrusion force. In the feedback system, aluminum film used as a feedback mirror is affixed to the back of the sample. When the light is reflected back into the cavity, as the reinjected light is imprinted with the birefringence information in the sample, the gain and polarization states of the laser are modulated. The variation of optical power and polarization states hopping is monitored to obtain the magnitude of the stress. The system has advantages such as simplicity and low-cost with a precision of 1.9 nm. Moreover, by adjusting the position of the aluminum, large-area samples can be measured anywhere at any place.

  1. Effect of horizontal fast electron beam position feedback on the performance of ESRF beamlines

    CERN Document Server

    Pascarelli, S

    2001-01-01

    ESRF is a state of the art third generation synchrotron light source optimized to produce very bright and collimated hard X-ray beams using insertion devices. Instabilities of the electron beam, resulting in source point transverse displacements, spoil these outstanding beam qualities. At the beginning of operation a fast active feedback system was installed to damp the transverse motion of the electron beam in the vertical plane. Recently it became evident that also the relatively smaller horizontal instabilities may have specific detrimental effects on the operation of particularly sensitive beamlines. The dispersive XAS beamline (ID24) was the first to benefit from the activation of a local horizontal feedback. Optimized to perform time-resolved studies and high-pressure experiments, its operation was strongly perturbed. This paper briefly describes the work carried out to identify and solve these problems, presenting the outcome of the implementation of a fast orbit feedback on this beamline.

  2. Midterm peer feedback in problem-based learning groups: the effect on individual contributions and achievement.

    Science.gov (United States)

    Kamp, Rachelle J A; van Berkel, Henk J M; Popeijus, Herman E; Leppink, Jimmie; Schmidt, Henk G; Dolmans, Diana H J M

    2014-03-01

    Even though peer process feedback is an often used tool to enhance the effectiveness of collaborative learning environments like PBL, the conditions under which it is best facilitated still need to be investigated. Therefore, this study investigated the effects of individual versus shared reflection and goal setting on students' individual contributions to the group and their academic achievement. In addition, the influence of prior knowledge on the effectiveness of peer feedback was studied. In this pretest-intervention-posttest study 242 first year students were divided into three conditions: condition 1 (individual reflection and goal setting), condition 2 (individual and shared reflection and goal setting), and condition 3 (control group). Results indicated that the quality of individual contributions to the tutorial group did not improve after receiving the peer feedback, nor did it differ between the three conditions. With regard to academic achievement, only males in conditions 1 and 2 showed better academic achievement compared with condition 3. However, there was no difference between both ways of reflection and goal setting with regard to achievement, indicating that both ways are equally effective. Nevertheless, it is still too early to conclude that peer feedback combined with reflection and goal setting is not effective in enhancing students' individual contributions. Students only had a limited number of opportunities to improve their contributions. Therefore, future research should investigate whether an increase in number of tutorial group meetings can enhance the effectiveness of peer feedback. In addition, the effect of quality of reflection and goal setting could be taken into consideration in future research.

  3. Supporting driver headway choice : The effects of discrete headway feedback when following headway instructions

    NARCIS (Netherlands)

    Risto, M.; Martens, M.H.

    2014-01-01

    With specific headway instructions drivers are not able to attain the exact headways as instructed. In this study, the effects of discrete headway feedback (and the direction of headway adjustment) on headway accuracy for drivers carrying out time headway instructions were assessed experimentally.

  4. Supporting driver headway choice: The effects of discrete headway feedback when following headway instructions

    NARCIS (Netherlands)

    Risto, Malte; Martens, Marieke Hendrikje

    2014-01-01

    With specific headway instructions drivers are not able to attain the exact headways as instructed. In this study, the effects of discrete headway feedback (and the direction of headway adjustment) on headway accuracy for drivers carrying out time headway instructions were assessed experimentally.

  5. The Effect of Frequency Altered Feedback on Stuttering Duration and Type

    Science.gov (United States)

    Stuart, Andrew; Frazier, Carmen L.; Kalinowski, Joseph; Vos, Paul W.

    2008-01-01

    Purpose: The effect of frequency altered feedback (FAF) on stuttering type (i.e., prolongation, repetition, or silent block) and stuttering duration (i.e., average duration of stuttering event and total stuttering time) was examined. Method: Retrospective analyses of previously collected data from 12 adult persons who stutter who participated in…

  6. The effects of EMG feedback training on state anxiety in introverts and extraverts.

    Science.gov (United States)

    Leboeuf, A

    1977-01-01

    The effect of EMG feedback on state anxiety was investigated in anxious introverts and extraverts. Although both groups learned to relax their muscles adequately, only the introverts reported a significant decrement in anxiety. Some extraverts reacted adversely to the technique, which suggests that other methods to inhibit anxiety may be necessary for this group.

  7. The Effect of Specific Feedback on Critical Reflection of Physical Therapy Students during Internships

    Science.gov (United States)

    Dye, Deanna; Scott, Karen Wilson; Ostrom, Lee; Devine, Nancy; Leight, Jennifer

    2011-01-01

    An essential component of expert professional practice is a practitioner's ability to critically reflect on one's performance. The purpose of this study was to determine the effect of specific electronic feedback provided by the coordinator of clinical education on students' critical reflection ability displayed in weekly journal writings during…

  8. The Relative Effectiveness of Different Types of Direct Written Corrective Feedback

    Science.gov (United States)

    Bitchener, John; Knoch, Ute

    2009-01-01

    The effectiveness of different types of written corrective feedback has been investigated over the last twenty years but it is still not possible to make firm conclusions about which options are the most beneficial to ESL learners. This article first provides an overview of the currently available research findings and then presents the results of…

  9. The effect of feedback by SMS-text messages and email on household electricity consumption

    DEFF Research Database (Denmark)

    Gleerup, Maria; Larsen, Anders; Leth-Petersen, Søren

    2010-01-01

    This paper analyzes the effect of supplying feedback by text messages (SMS) and email about electricity consumption on the level of total household electricity consumption. An experiment was conducted in which 1,452 households were randomly allocated to three experimental groups and two control...

  10. Improving shop floor compliance with age restrictions for alcohol sales: Effectiveness of a feedback letter intervention

    NARCIS (Netherlands)

    van Hoof, Joris Jasper; Gosselt, Jordi Franciscus; Baas, N.; de Jong, Menno D.T.

    2012-01-01

    Purpose: In this study, we investigated the effects and handling of an intervention to increase compliance with age limits regarding alcohol sales. The intervention tested in this field experiment was a feedback letter sent to alcohol outlets about their individual compliance results based on a

  11. Self-regulated learning: A key learning effect of feedback in a ...

    African Journals Online (AJOL)

    Self-regulated learning: A key learning effect of feedback in a problem-based learning context. ... Small-group student tutorials are a major component of PBL. ... qualitative study in which individual interviews and focus group discussions were ...

  12. The Effect of Frequency Altered Feedback on Stuttering Duration and Type

    Science.gov (United States)

    Stuart, Andrew; Frazier, Carmen L.; Kalinowski, Joseph; Vos, Paul W.

    2008-01-01

    Purpose: The effect of frequency altered feedback (FAF) on stuttering type (i.e., prolongation, repetition, or silent block) and stuttering duration (i.e., average duration of stuttering event and total stuttering time) was examined. Method: Retrospective analyses of previously collected data from 12 adult persons who stutter who participated in…

  13. Improving shop floor compliance with age restrictions for alcohol sales: Effectiveness of a feedback letter intervention

    NARCIS (Netherlands)

    Hoof, van Joris J.; Gosselt, Jordy F.; Baas, Niels; Jong, de Menno D.T.

    2012-01-01

    Purpose: In this study, we investigated the effects and handling of an intervention to increase compliance with age limits regarding alcohol sales. The intervention tested in this field experiment was a feedback letter sent to alcohol outlets about their individual compliance results based on a myst

  14. Feedback Effects on the Performance and Self-Reinforcing Behavior of Elderly and Young Adult Women

    Science.gov (United States)

    Bellucci, Georgette; Hoyer, William J.

    1975-01-01

    A total of 64 college-aged and elderly women participated in an experimental study of the effects of noncontingent positive feedback on simple speeded performance, performance self-evaluations, and self-reinforcing behavior. Younger women self-reinforced more and held higher self-evaluations of their performance than elderly women. (Author)

  15. Exergaming for elderly: : effects of different types of game feedback on performance of a balance task.

    NARCIS (Netherlands)

    Lamoth, Claude; Alingh, Rolinde; Caljouw, Simone; Wiederhold, B.K.; Riva, G.

    Balance training to improve postural control in elderly can contribute to the prevention of falls. Video games that require body movements have the potential to improve balance. However, research about the effects of type of visual feedback (i.e. the exergame) on the quality of movement and

  16. The effect of visual feedback and training in auditory-perceptual judgment of voice quality

    NARCIS (Netherlands)

    Barsties, Ben; Beers, Mieke; Ten Cate, Liesbeth; Van Ballegooijen, Karin; Braam, Lilian; De Groot, Merel; Van Der Kant, Marieke; Kruitwagen, Cas|info:eu-repo/dai/nl/304826790; Maryn, Youri

    2017-01-01

    The aim of the present investigation was to evaluate the effect of visual feedback on rating voice quality severity level and the reliability of voice quality judgment by inexperienced listeners. For this purpose two training programs were created, each lasting 2 hours. In total 37 undergraduate spe

  17. Effects of a Video-Feedback Intervention on Teachers' Use of Praise

    Science.gov (United States)

    Pinter, Erika Blood; East, Allison; Thrush, Nicole

    2015-01-01

    The purpose of this study was to examine the effects of a video-feedback intervention on the frequency of teachers' use of (a) general group praise, (b) general individual praise, (c) specific group praise, (d) specific individual praise, (e) negative comments directed toward the entire class, and (f) negative comments directed toward an…

  18. Perceptions of Effectiveness, Fairness and Feedback of Assessment Methods: A Study in Higher Education

    Science.gov (United States)

    Flores, Maria Assunção; Veiga Simão, Ana Margarida; Barros, Alexandra; Pereira, Diana

    2015-01-01

    This paper draws upon a broader piece of research aimed at investigating assessment in higher education. It focuses upon the perceptions of undergraduates about issues of effectiveness, fairness and feedback, particularly in regard to the so-called learner-centred methods. In total, 378 undergraduate students participated in the study at the…

  19. Exergaming for elderly: : effects of different types of game feedback on performance of a balance task.

    NARCIS (Netherlands)

    Lamoth, Claude; Alingh, Rolinde; Caljouw, Simone; Wiederhold, B.K.; Riva, G.

    2012-01-01

    Balance training to improve postural control in elderly can contribute to the prevention of falls. Video games that require body movements have the potential to improve balance. However, research about the effects of type of visual feedback (i.e. the exergame) on the quality of movement and experien

  20. Effects of Reading Curriculum-Based Measurement (R-CBM) Teacher Feedback in General Education Classrooms

    Science.gov (United States)

    Graney, Suzanne Bamonto; Shinn, Mark R.

    2005-01-01

    This study examined the effects of teacher feedback from Reading Curriculum-Based Measurement (R-CBM) progress results for low-performing students in general education classrooms. Participants included 44 second-grade teachers and 184 students in their low reading groups. After 5 weeks of progress monitoring, teachers in the two experimental…

  1. The Effects of Feedback Timing on Learning Facts: The Role of Response Confidence.

    Science.gov (United States)

    Webb, James M.; And Others

    1994-01-01

    Effects of immediate and delayed feedback on learning were studied in 2 experiments involving 120 undergraduate students. Subjects answered 90 general information multiple-choice items on 2 different occasions 1 week apart. Subjects rated their confidence in their responses. Results provide support for the Kulhavy and Stock model and the…

  2. The Effects of the Timing of Corrective Feedback on the Acquisition of a New Linguistic Structure

    Science.gov (United States)

    Li, Shaofeng; Zhu, Yan; Ellis, Rod

    2016-01-01

    The article reports on a study investigating the comparative effects of immediate and delayed corrective feedback in learning the English past passive construction, a linguistic structure of which the learners had little prior knowledge. A total of 120 learners of English as a foreign language (EFL) from 4 intact classes at a Chinese middle school…

  3. Effects of Peer E-Feedback on Turkish EFL Students' Writing Performance

    Science.gov (United States)

    Ciftci, Hatime; Kocoglu, Zeynep

    2012-01-01

    The present study investigated the effect of online peer feedback through blogs on Turkish EFL students' writing performance and their perceptions. Data were collected by using: a) Turkish EFL Students' Background Survey, b) interviews at the beginning and end of the term, c) first and revised drafts, and d) end-of-semester Questionnaire. The…

  4. The Effect of Two Types of Corrective Feedback on EFL Learners' Writing Skill

    Science.gov (United States)

    Farshi, Sina Soltanabadi; Safa, Saeedeh Khalili

    2015-01-01

    The purpose of this study was to compare the effects of two types of corrective feedback on EFL learners' writing skill. Thirty five advanced learners in three groups participated in this study. Structures of written texts were taught in all three classes during fourteen sessions of treatment; and each session, a related topic was given and the…

  5. Effectiveness of remote feedback on physical activity in persons with type 2 diabetes

    DEFF Research Database (Denmark)

    Kongstad, Malte Bue; Valentiner, Laura Staun; Ried-Larsen, Mathias

    2017-01-01

    characteristics using these as covariates. Results The literature search identified 4455 articles of which 27 met the eligibility criteria. The meta-analysis including a total of 4215 participants found an overall effect size in favour of remote feedback interventions compared to standardized treatment, SMD = 0...

  6. The effect of haptic guidance and visual feedback on learning a complex tennis task.

    Science.gov (United States)

    Marchal-Crespo, Laura; van Raai, Mark; Rauter, Georg; Wolf, Peter; Riener, Robert

    2013-11-01

    While haptic guidance can improve ongoing performance of a motor task, several studies have found that it ultimately impairs motor learning. However, some recent studies suggest that the haptic demonstration of optimal timing, rather than movement magnitude, enhances learning in subjects trained with haptic guidance. Timing of an action plays a crucial role in the proper accomplishment of many motor skills, such as hitting a moving object (discrete timing task) or learning a velocity profile (time-critical tracking task). The aim of the present study is to evaluate which feedback conditions-visual or haptic guidance-optimize learning of the discrete and continuous elements of a timing task. The experiment consisted in performing a fast tennis forehand stroke in a virtual environment. A tendon-based parallel robot connected to the end of a racket was used to apply haptic guidance during training. In two different experiments, we evaluated which feedback condition was more adequate for learning: (1) a time-dependent discrete task-learning to start a tennis stroke and (2) a tracking task-learning to follow a velocity profile. The effect that the task difficulty and subject's initial skill level have on the selection of the optimal training condition was further evaluated. Results showed that the training condition that maximizes learning of the discrete time-dependent motor task depends on the subjects' initial skill level. Haptic guidance was especially suitable for less-skilled subjects and in especially difficult discrete tasks, while visual feedback seems to benefit more skilled subjects. Additionally, haptic guidance seemed to promote learning in a time-critical tracking task, while visual feedback tended to deteriorate the performance independently of the task difficulty and subjects' initial skill level. Haptic guidance outperformed visual feedback, although additional studies are needed to further analyze the effect of other types of feedback visualization on

  7. Frequency Locking and Monitoring Based on Bi-directional Terahertz Radiation of a 3rd-Order Distributed Feedback Quantum Cascade Laser

    NARCIS (Netherlands)

    Van Marrewijk, N.; Mirzaei, B.; Hayton, D.; Gao, J.R.; Kao, T.Y.; Hu, Q.; Reno, J.L.

    2015-01-01

    We have performed frequency locking of a dual, forward reverse emitting third-order distributed feedback quantum cascade laser (QCL) at 3.5 THz. By using both directions of THz emission in combination with two gas cells and two power detectors, we can for the first time perform frequency stabilizati

  8. Optical generation of microwave signals with a dual-phase-shifted Al2O3:Yb3+ distributed-feedback laser

    NARCIS (Netherlands)

    Bernhardi, E.H.; Khan, M.R.H.; Roeloffzen, C.G.H.; Wolferen, van H.A.G.M.; Wörhoff, K.; Ridder, de R.M.; Pollnau, M.

    2012-01-01

    We demonstrate the optical generation of stable microwave signals from a dual-wavelength distributed-feedback waveguide laser in ytterbium-doped alumina. The microwave beat signal was produced at ~15 GHz with a frequency stability of ±2.5 MHz.

  9. Audio Feedback -- Better Feedback?

    Science.gov (United States)

    Voelkel, Susanne; Mello, Luciane V.

    2014-01-01

    National Student Survey (NSS) results show that many students are dissatisfied with the amount and quality of feedback they get for their work. This study reports on two case studies in which we tried to address these issues by introducing audio feedback to one undergraduate (UG) and one postgraduate (PG) class, respectively. In case study one…

  10. Improving the Subgrid-Scale Representation of Hydrometeors and Microphysical Feedback Effects Using a Multivariate PDF

    Science.gov (United States)

    Griffin, Brian M.

    The subgrid-scale representation of hydrometeor fields is important for calculating microphysical process rates. In order to represent subgrid-scale variability, the Cloud Layers Unified By Binormals (CLUBB) parameterization uses a multivariate Probability Density Function (PDF). In addition to vertical velocity, temperature, and moisture fields, the PDF includes hydrometeor fields. Previously, each hydrometeor field was assumed to follow a multivariate single lognormal distribution. Now, in order to better represent the distribution of hydrometeors, two new multivariate PDFs are formulated and introduced in part one of this two-part project. The new PDFs represent hydrometeors using either a delta-lognormal or a delta-double-lognormal shape. The two new PDF distributions, plus the previous single lognormal shape, are compared to histograms of data taken from Large-Eddy Simulations (LES) of a precipitating cumulus case, a drizzling stratocumulus case, and a deep convective case. Finally, the warm microphysical process rates produced by the different hydrometeor PDFs are compared to the same process rates produced by the LES. Microphysics processes have feedback effects on moisture and heat content. Not only do these processes influence mean values, but also variability and fluxes of moisture and heat content. For example, evaporation of rain below cloud base may produce cold pools. This evaporative cooling may increase the variability in temperature in the below-cloud layer. Likewise, rain production in the moistest part of cloud tends to decrease variability in cloud water. These effects are usually not included in most coarse-resolution weather and climate models, or else are crudely parameterized. In part two of this two-part project, the microphysical effects on moisture and heat content are parameterized using the PDF method. This approach is based on predictive, horizontally-averaged equations for the variances, covariances, and fluxes of moisture and heat

  11. The effect of negative feedback on tension and subsequent performance: the main and interactive effects of goal content and conscientiousness.

    Science.gov (United States)

    Cianci, Anna M; Klein, Howard J; Seijts, Gerard H

    2010-07-01

    The purpose of this experiment was to examine the interplay of goal content, conscientiousness, and tension on performance following negative feedback. Undergraduate students were assigned either a learning or performance goal and then were provided with false feedback indicating very poor performance on the task they performed. After assessing tension, participants performed the task again with the same learning or performance goal. A mediated moderation model was tested, and results were supportive of our hypotheses. Specifically, individuals assigned a learning goal experienced less tension and performed better following negative feedback than individuals assigned a performance goal. Individuals high in conscientiousness experienced greater tension than individuals low in conscientiousness. Conscientiousness and goal content interacted in relating to both tension and performance, with tension as a mediator, such that high conscientiousness amplified the detrimental effect of a performance goal on tension following negative feedback leading to lower performance. High conscientiousness facilitated performance for participants with a learning goal.

  12. The effects of AGN feedback and SPH formulation on black hole growth in galaxies

    Science.gov (United States)

    Liu, MaoSheng; Di Matteo, Tiziana; Feng, Yu

    2016-05-01

    We perform simulations of isolated galaxies and major mergers to investigate the effects on black hole (BH) growth due to variations in active galactic nuclei (AGN) feedback models and different smooth particle hydrodynamic (SPH) solvers. In particular we examine density-SPH versus newer pressure-SPH formulation and their significance relative to minor changes in subgrid AGN feedback prescriptions. The aim is to use these idealized simulations to understand the impact of these effects for large cosmological volume simulations where these models are often adopted. In both isolated galaxies and galaxy mergers, we find that star formation histories are largely insensitive to the choice of SPH schemes whilst BH accretion rate can change. This can result in a factor of 2-3 difference in final BH mass for the two hydrodynamic formulations. However, the differences are much smaller than those obtained even with small changes in the subgrid AGN feedback prescription. In particular, depending on the size of the region and the manner in which the AGN energy is deposited, the star formation rate is suppressed by a factor of 2 in isolated galaxies and the star burst completely quenched during the coalescence of two galaxies. The final BH mass differs by over an order of magnitude by changes in AGN feedback model. Our results indicated that any change in the hydrodynamic formulation is likely subdominant to the effects of changing subgrid physics around the BH, although thermodynamic state and morphology of the gas remnant are also sensitive to the change in hydrodynamic solver.

  13. Types of Feedback in Competency-Based Predoctoral Orthodontics: Effects on Students' Attitudes and Confidence.

    Science.gov (United States)

    Lipp, Mitchell J; Cho, Kiyoung; Kim, Han Suk

    2017-05-01

    Feedback can exert a powerful influence on learning and achievement although its effect varies. The aim of this study was to investigate the effects of three types of feedback on dental students' attitudes and confidence in a competency-based course in predoctoral orthodontics at New York University College of Dentistry. In 2013-14, all 253 third-year students in a course using test-enhanced instructional methods received written feedback on formative assessments. The type of feedback varied across three groups: pass/fail grades (PF) N=77, emoticons (EM) N=90, or written comments (WC) N=86. At the end of the course, students completed surveys that included four statements addressing their attitudes toward course instruction and confidence in their abilities. The survey response rate ranged from 75% to 100% among groups. The lowest response rate (75%) was in the PF group. In attitudes toward course instruction and confidence in their abilities, the WC group trended to more positive responses than the other groups, while the PF group trended to negative responses. On two of the four statements, the trend for the WC group was significant (95% CI). In both statements concerning attitudes toward instruction, the PF group trended to negative responses that were significant (95% CI). These results support the effectiveness of descriptive written comments over pass/fail grades or emoticons in improving dental students' confidence in their abilities and their attitudes toward instruction.

  14. "Just Dance": The Effects of Exergame Feedback and Controller Use on Physical Activity and Psychological Outcomes.

    Science.gov (United States)

    Lin, Jih-Hsuan

    2015-06-01

    In Asia, dance games are among the most popular types of exergames. Whereas traditional dance-based games emphasize step movements on a dance pad, more recent dance games emphasize intuitive dance movements using simple controllers or players' own bodies to "just dance." However, because of limited space and access, young adults in Taiwan often do not use these games. Popular dance videos on YouTube are more readily available to students because these videos can be accessed on a computer. Therefore, the current study examines the effects of interactivity (the role of feedback) and controller use on participants' physiological and psychological outcomes during exergames. The dance game "Just Dance 3" (Ubisoft, Montreuil, France) was chosen as the stimulus for this study. Participants danced through one song for rehearsal and warm-up, followed by three songs for the experiment, which lasted approximately 12 minutes. One hundred twenty-nine college students participated in a 2×2×2 (interactivity, feedback versus no feedback; controller, with versus without; sex, male versus female) between-subject factorial design. A series of 2×2×2 (interactivity, controller, and sex) analyses of variance showed no significant differences in interaction effects on participants' heart rates, blood pressures, body movements, step counts, or perceived psychological outcomes. Dance game videos without feedback are also effective tools for achieving moderate-level exercise intensity. These videos can supplement the limited access to games in Asian countries, such as Taiwan.

  15. Effects of solar UV radiation and climate change on biogeochemical cycling: interactions and feedbacks

    OpenAIRE

    Zepp, R. G.; D. J. Erickson; Paul, N.D.; Sulzberger, B.

    2011-01-01

    Solar UV radiation, climate and other drivers of global change are undergoing significant changes and models forecast that these changes will continue for the remainder of this century. Here we assess the effects of solar UV radiation on biogeochemical cycles and the interactions of these effects with climate change, including feedbacks on climate. Such interactions occur in both terrestrial and aquatic ecosystems. While there is significant uncertainty in the quantification of these effects,...

  16. Effect Of Feedback On The Escape Of Ionizing Radiation From High-Z Galaxies

    Science.gov (United States)

    Trebitsch, Maxime; Blaizot, Jérémy; Rosdahl, Joakim; Devriendt, Julien; Slyz, Adrianne

    2017-06-01

    Quantifying how much of the ionizing radiation produced in high-redshift galaxies escapes in the IGM is one of the main challenges in understanding the sources of reionization. We investigate the radiative properties of simulated low mass galaxies (halos of a few 109 Msun at z=6), where radiation is modelled on-the-fly, and different sources of feedback (from stars and AGN) are included. Using radiation-hydrodynamic simulations performed with Ramses-RT we study how the energy and momentum input from supernovae and black hole activity modulates the properties of the interstellar medium and therefore how, and how many, photons can escape from the galaxy. I will present simulations showing (Trebitsch et al. 2017, https://arxiv.org/abs/1705.00941) that stellar feedback has a pivotal role in regulating the escape fraction in dwarf galaxies. Supernovae carve holes in the gas distribution, through which ionizing photons can escape.

  17. Effects of remote feedback in home-based physical activity interventions for older adults : A systematic review

    NARCIS (Netherlands)

    Geraedts, Hilde; Zijlstra, Agnes; Bulstra, Sjoerd K.; Stevens, Martin; Zijlstra, Wiebren

    2013-01-01

    Objective: To evaluate the literature on effectiveness of remote feedback on physical activity and capacity in home-based physical activity interventions for older adults with or without medical conditions. In addition, the effect of remote feedback on adherence was inventoried. Methods: A systemati

  18. The Effect of Six Different Corrective Feedback Strategies on Iranian English Language Learners’ IELTS Writing Task 2

    OpenAIRE

    Reza Vahdani Sanavi; Majid Nemati

    2014-01-01

    Scholars have long studied the effect of corrective feedback strategies on the writing ability of language learners, but few have formed designs in which more than three feedback strategies have been used. In this research, the ultimate goal was to discover how International English Language Testing System (IELTS-) candidates could be helped to perform better in the writing component of the test with the feedback they ...

  19. The effects of context and feedback on age differences in spoken word recognition.

    Science.gov (United States)

    Stine-Morrow, E A; Soederberg Miller, L M; Nevin, J A

    1999-03-01

    We investigated the hypothesis that age differences in speech discrimination would be reduced by enhancing the distinctiveness of the speech processing event in terms of both the context of encoding and the response outcome. Younger and older adults performed an auditory lexical decision task in which the degree of semantic constraint (context) and type of feedback were manipulated. Main effects of age indicated that older adults generally showed lower discriminability (D) and greater bias (B) toward reporting signals to be words. Consistent with the environmental support hypothesis, older adults were differentially facilitated in discriminability by feedback, but only when semantic context was provided. Also, for both younger and older adults, feedback and context each had the effect of reducing bias and facilitating the speed of rejecting nonwords. Contrary to one suggestion in the literature that aging brings an insensitivity to environmental contingency, older adults were at least as capable as the young in taking advantage of feedback to normalize the speech signal so as to increase discriminability and decrease bias.

  20. The effect of visual feedback and training in auditory-perceptual judgment of voice quality.

    Science.gov (United States)

    Barsties, Ben; Beers, Mieke; Ten Cate, Liesbeth; Van Ballegooijen, Karin; Braam, Lilian; De Groot, Merel; Van Der Kant, Marieke; Kruitwagen, Cas; Maryn, Youri

    2017-04-01

    The aim of the present investigation was to evaluate the effect of visual feedback on rating voice quality severity level and the reliability of voice quality judgment by inexperienced listeners. For this purpose two training programs were created, each lasting 2 hours. In total 37 undergraduate speech-language therapy students participated in the study and were divided into a visual plus auditory-perceptual feedback group (V + AF), an auditory-perceptual feedback group (AF), and a control group with no feedback (NF). All listeners completed two rating sessions judging overall severity labeled as grade (G), roughness (R), and breathiness (B). The judged voice samples contained the concatenation of continuous speech and sustained phonation. No significant rater reliability changes were found in the pre- and posttest between the three groups in every GRB-parameter (all p > 0.05). There was a training effect seen in the significant improvement of rater reliability for roughness within the NF and AF groups (all p visual and auditory anchors while rating as well as longer training sessions may be required to draw a firm conclusion.

  1. Effectiveness of the aldosterone-sodium and -potassium feedback control system.

    Science.gov (United States)

    Young, D B; McCaa, R E; Pan, U J; Guyton, A C

    1976-09-01

    This study was conducted to determine the quantitative importance of the aldosterone feedback mechanism in controlling each one of three major factors that have often been associated with aldosterone, namely, extracellular fluid sodium concentration, extracellular fluid potassium concentration, and extracellular fluid volume. To do this, the ability of the body to control these three factors in the face of marked changes in daily sodium or potassium intake was studied under two conditions: 1) in the normal dog, and 2) in the dog in which the aldosterone feedback mechanism was prevented from functioning by removing the adrenal glands and then providing a continuous fixed level of supportive aldosterone and glucocorticoids during the low and high electrolyte intake periods. Under these conditions, removal of feedback control of aldosterone secretion decreased the effectiveness of plasma potassium control by nearly fivefold (39% vs. 8% change in plasma potassium concentration), fluid volume by sixfold (12% vs. 2% change in sodium space) and had no effect on control of plasma sodium concentration (2% change with and without feedback control of aldosterone secretion.)

  2. Diode-Pumped Organo-Lead Halide Perovskite Lasing in a Metal-Clad Distributed Feedback Resonator.

    Science.gov (United States)

    Jia, Yufei; Kerner, Ross A; Grede, Alex J; Brigeman, Alyssa N; Rand, Barry P; Giebink, Noel C

    2016-07-13

    Organic-inorganic lead halide perovskite semiconductors have recently reignited the prospect of a tunable, solution-processed diode laser, which has the potential to impact a wide range of optoelectronic applications. Here, we demonstrate a metal-clad, second-order distributed feedback methylammonium lead iodide perovskite laser that marks a significant step toward this goal. Optically pumping this device with an InGaN diode laser at low temperature, we achieve lasing above a threshold pump intensity of 5 kW/cm(2) for durations up to ∼25 ns at repetition rates exceeding 2 MHz. We show that the lasing duration is not limited by thermal runaway and propose instead that lasing ceases under continuous pumping due to a photoinduced structural change in the perovskite that reduces the gain on a submicrosecond time scale. Our results indicate that the architecture demonstrated here could provide the foundation for electrically pumped lasing with a threshold current density Jth < 5 kA/cm(2) under sub-20 ns pulsed drive.

  3. Optically pumped distributed feedback dye lasing with slide-coated TiO₂ inverse-opal slab as Bragg reflector.

    Science.gov (United States)

    Han, Sung Gu; Lim, Jongchul; Shin, Jinsub; Lee, Sung-Min; Park, Taiho; Yoon, Jongseung; Woo, Kyoungja; Lee, Hyunjung; Lee, Wonmok

    2014-08-15

    We demonstrate an optical amplification of organic dye within a TiO2 inverse-opal (IO) distributed feedback (DFB) reflector prepared by a slide-coating method. Highly reflective TiO2 IO film was fabricated by slide coating the binary aqueous dispersions of polystyrene microspheres and charge-stabilized TiO2 nanoparticles on a glass slide and subsequently removing the polymer-opal template. TiO2 IO film was infiltrated, in turn, with the solutions of DCM, a fluorescent dye in various solvents with different indices of refraction. Optical pumping by frequency-doubled Nd:YAG laser resulted in amplified spontaneous emission in each dye solution. In accordance with the semi-empirical simulation by the FDTD method, DCM in ethanol showed the best emission/stopband matching for the TiO2 IO film used in this study. Therefore, photo excitation of a DCM/ethanol cavity showed a single-mode DFB lasing at 640 nm wavelength at moderate pump energy.

  4. Continuous wave operation of distributed feedback quantum cascade lasers with low threshold voltage and low power consumption

    Science.gov (United States)

    Xie, Feng; Caneau, Catherine; LeBlanc, Herve P.; Coleman, Sean; Hughes, Lawrence C.; Zah, Chung-en

    2012-03-01

    We demonstrated the room temperature continuous wave (CW) operation of mid-infrared distributed feedback (DFB) quantum cascade lasers (QCLs) made of strain balanced GaInAs/AlInAs material on InP substrates for sensing CO2 isotope and N2O gas for potential applications that need battery powered portable devices in a sensor network. For the former device at 4.35 μm wavelength, we demonstrated a low threshold voltage of less than 8 V for battery operation and a near circular far field pattern with small divergent angles of 33 by 28 degrees full width at half maximum (FWHM) in vertical and horizontal directions, respectively, for easy collimation. For the latter device at 4.5 μm wavelength, we demonstrated a low CW threshold power consumption of 0.7 W at 20 °C. A side mode suppression ratio (SMSR) of 30 dB was achieved within the whole operating current and temperature ranges for both lasers.

  5. Active vibration mitigation of distributed parameter, smart-type structures using Pseudo-Feedback Optimal Control (PFOC)

    Science.gov (United States)

    Patten, W. N.; Robertshaw, H. H.; Pierpont, D.; Wynn, R. H.

    1989-01-01

    A new, near-optimal feedback control technique is introduced that is shown to provide excellent vibration attenuation for those distributed parameter systems that are often encountered in the areas of aeroservoelasticity and large space systems. The technique relies on a novel solution methodology for the classical optimal control problem. Specifically, the quadratic regulator control problem for a flexible vibrating structure is first cast in a weak functional form that admits an approximate solution. The necessary conditions (first-order) are then solved via a time finite-element method. The procedure produces a low dimensional, algebraic parameterization of the optimal control problem that provides a rigorous basis for a discrete controller with a first-order like hold output. Simulation has shown that the algorithm can successfully control a wide variety of plant forms including multi-input/multi-output systems and systems exhibiting significant nonlinearities. In order to firmly establish the efficacy of the algorithm, a laboratory control experiment was implemented to provide planar (bending) vibration attenuation of a highly flexible beam (with a first clamped-free mode of approximately 0.5 Hz).

  6. Study of a distributed feedback diode laser based hygrometer combined Herriot-gas cell and waterless optical components

    Science.gov (United States)

    Wei, Yubin; Chang, Jun; Lian, Jie; Wang, Qiang; Wei, Wei

    2016-09-01

    A distributed feedback diode laser (DFB-DL) based hygrometer combined with a long-path-length Herriot gas cell and waterless optical components was proposed and investigated. The main function of this sensor was to simultaneously improve the measurement reliability and resolution. A comparison test between a 10-cm normal transmission-type gas cell and a 3-m Herriot gas cell was carried out to demonstrate the improvement. Reliability improvement was achieved by influence suppression of water vapor inside optical components (WVOC) through combined action of the Herriot gas cell and waterless optical components. The influence of WVOC was suppressed from 726 ppmv to 25 ppmv using the Herriot gas cell. Moreover, combined with waterless optical components, the influence of WVOC was further suppressed to no more than 4 ppmv. Resolution improvement from 11.7 ppmv to 0.32 ppmv was achieved mainly due to the application of the long-path-length Herriot gas cell. The results show that the proposed sensor has a good performance and considerable potential application in gas sensing, especially when probed gas possibly permeates into optical components.

  7. Cross Feedback Control of a Magnetic Bearing System: Controller Design Considering Gyroscopic Effects

    Science.gov (United States)

    Ahrens, Markus; Kucera, Ladislav

    1996-01-01

    For flywheel rotors or other rotors with significant ratios of moments of inertia, the influence of gyroscopic effects has to be considered. While conservative or damped systems remain stable even under gyroscopic effects, magnetically suspended rotors can be destabilized with increasing rotational speed. The influence of gyroscopic effects on the stability and behavior of a magnetic bearing system is analyzed. The analysis is carried out with a rigid body model for the rotor and a nonlinear model for the magnetic bearing and its amplifier. Cross feedback control can compensate gyroscopic effects. This compensation leads to better system performance and can avoid instability. Furthermore, the implementation of this compensation is simple. The main structure of a decentralized controller can still be used. It has only to be expanded by the cross feedback path.

  8. Effective English writing feedback exploration%有效的英语写作反馈探究

    Institute of Scientific and Technical Information of China (English)

    廖素清

    2016-01-01

    This paper analyzes the feedback in colege English writing teaching situation and existing problems. Through the empirical research on teacher feedback and peer feedback, electronic feedback , three feedbacks impact on English writing teaching, to find out effective ways of feedback in order to improve the students' English writing.%本文分析了高校英语写作教学中反馈的现状以及存在的问题。通过实证研究教师反馈、同伴反馈、电子反馈三种反馈形式对英语写作教学所产生的影响,旨在找出有效的反馈方式,以提高学生的英语写作水平。

  9. Effects of self-control and instructor-control feedback on motor learning in individuals with cerebral palsy.

    Science.gov (United States)

    Hemayattalab, Rasool

    2014-11-01

    In this study we investigated the effects of "self-control and instructor-control feedback" on motor learning in individuals with cerebral palsy (CP). For this reason 22 boy students with CP type I (12.26±3.11 years of age) were chosen. They were put into self-control feedback, instructor-control feedback and control groups. All participants practiced dart throwing skill for 5 sessions (4 blocks of 5 trails each session). The self-control group received knowledge of results (KR) feedback for half of their trials whenever they wanted. The instructor-control group received KR feedback after half of both their good and bad trails. The control group received no feedback for any trails. The acquisition test was run immediately at the end of each practice session (the last block) and the retention and transfer tests were run 24h following the acquisition phase. Analyses of variance with repeated measures and Post hoc tests were used to analyze the data. According to the results of this study, individuals with CP have the ability of acquiring and retaining a new motor skill. Also, it was found that self-control feedback is effective than instructor-control feedback on learning of a motor task in individuals with CP as in the average population. These findings show that rules regarding feedback also apply to people afflicted with CP. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Effect of intermittent feedback control on robustness of human-like postural control system

    Science.gov (United States)

    Tanabe, Hiroko; Fujii, Keisuke; Suzuki, Yasuyuki; Kouzaki, Motoki

    2016-03-01

    Humans have to acquire postural robustness to maintain stability against internal and external perturbations. Human standing has been recently modelled using an intermittent feedback control. However, the causality inside of the closed-loop postural control system associated with the neural control strategy is still unknown. Here, we examined the effect of intermittent feedback control on postural robustness and of changes in active/passive components on joint coordinative structure. We implemented computer simulation of a quadruple inverted pendulum that is mechanically close to human tiptoe standing. We simulated three pairs of joint viscoelasticity and three choices of neural control strategies for each joint: intermittent, continuous, or passive control. We examined postural robustness for each parameter set by analysing the region of active feedback gain. We found intermittent control at the hip joint was necessary for model stabilisation and model parameters affected the robustness of the pendulum. Joint sways of the pendulum model were partially smaller than or similar to those of experimental data. In conclusion, intermittent feedback control was necessary for the stabilisation of the quadruple inverted pendulum. Also, postural robustness of human-like multi-link standing would be achieved by both passive joint viscoelasticity and neural joint control strategies.

  11. Mass Transport and Turbulence in Gravitationally Unstable Disk Galaxies II: The Effects of Star Formation Feedback

    CERN Document Server

    Goldbaum, Nathan J; Forbes, John C

    2016-01-01

    Self-gravity and stellar feedback are capable of driving turbulence and transporting mass and angular momentum in disk galaxies, but the balance between them is not well understood. In the previous paper in this series, we showed that gravity alone can drive turbulence in galactic disks, regulate their Toomre $Q$ parameters to $\\sim$ 1, and transport mass inwards at a rate sufficient to fuel star formation in the centers of present-day galaxies. In this paper we extend our models to include the effects of star formation feedback. We show that feedback suppresses galaxies' star formation rates by a factor of $\\sim$ 5 and leads to the formation of a multi-phase atomic and molecular ISM. Both the star formation rate and the phase balance produced in our simulations agree well with observations of nearby spirals. After our galaxies reach steady state, we find that the inclusion of feedback actually lowers the gas velocity dispersion slightly compared to the case of pure self-gravity, and also slightly reduces the...

  12. The effect of emotions, promotion vs. prevention focus, and feedback on cognitive engagement

    Directory of Open Access Journals (Sweden)

    Wytykowska Agata

    2015-09-01

    Full Text Available The purpose of the study was to explore the role of emotions, promotion-prevention orientation and feedback on cognitive engagement. In the experiment participants had the possibility to engage in a categorization task thrice. After the first categorization all participants were informed that around 75% of their answers were correct. After the second categorization, depending on the experimental condition, participants received feedback either about success or failure. Involvement in the third categorization was depended on participants’ decision whether to take part in it or not. Each time, before and after categorization, the emotional state was assessed. Results showed that promotion orientation predicted experiencing curiosity before the task, which in turn led to a higher cognitive engagement in the first categorization. Promotion and prevention orientation moderated the type of emotional response to positive feedback. Promotion orientation also predicted cognitive engagement after the feedback of success was provided. Generally results confirmed the positive effect of positive emotions as well as promotion orientation on cognitive engagement.

  13. THE EFFECT OF TEACHER ERROR FEEDBACK ON THE ACCURACY OF EFL STUDENT WRITING

    Directory of Open Access Journals (Sweden)

    Yi-chun Pan

    2010-02-01

    Full Text Available This study investigated the effect of teacher error feedback on students' ability to write accurately. Three male first-year Physics graduate students at a university in Taiwan participated in this study. They were asked to write a 100-word passage about the greatest invention in human history. Within days of the teacher’s grammatical feedback, the students were required to revise their work again based on the teacher's suggested revisions. In addition, oral conferencing was conducted in order to help the students obtain a better comprehension of certain grammar points. Four weeks after the oral conferencing, the students were asked, without prior notice, to revise their original passages again. The findings reveal that the students made progress in the revised versions of their passages, but the success was not repeated in their later test versions. In other words, no positive relationship between teacher error feedback and students’ improvement in linguistic accuracy over time was observed. This suggests that teacher error feedback alone may not facilitate the learning of linguistic information. A combination of sufficient exposure to English in reading and writing, plus opportunities to practice the language, for example, may lead to better grammar.

  14. Feedback valence affects auditory perceptual learning independently of feedback probability

    OpenAIRE

    Amitay, S.; Moore, D. R.; Molloy, K.; Halliday, L. F.

    2015-01-01

    Previous studies have suggested that negative feedback is more effective in driving learning than positive feedback. We investigated the effect on learning of providing varying amounts of negative and positive feedback while listeners attempted to discriminate between three identical tones; an impossible task that nevertheless produces robust learning. Four feedback conditions were compared during training: 90% positive feedback or 10% negative feedback informed the participants that they wer...

  15. The reflexive influence of the feedback of reaction time, "expectancy wave" (CNV) and heart-frequency: Specific and nonspecific effects.

    NARCIS (Netherlands)

    Godaert, G.; Kok, A.; van Hechten, H.; Driehuis, H.J.

    1973-01-01

    Studied the influence of feedback on the attending processes. Ss were 36 16-31 yr old male candidates for the air service. The effects of the feedback were varying length of the reaction time (RT), the "contingent negative variation" (CNV), and the variation in heart frequency. The CNV, measured by

  16. The reflexive influence of the feedback of reaction time, expectancy wave (CNV) and heart-frequency: Specific and nonspecific effects.

    NARCIS (Netherlands)

    Godaert, G.; van Hechten, H.; Driehuis, H.J.; Kok, A.

    1973-01-01

    Studied the influence of feedback on the attending processes. Ss were 36 16-31 yr old male candidates for the air service. The effects of the feedback were varying length of the reaction time (RT), the "contingent negative variation" (CNV), and the variation in heart frequency. The CNV, measured by

  17. Effectiveness of a Training Program in Supervisors' Ability to Provide Feedback on Residents' Communication Skills

    Science.gov (United States)

    Junod Perron, Noelle; Nendaz, Mathieu; Louis-Simonet, Martine; Sommer, Johanna; Gut, Anne; Baroffio, Anne; Dolmans, Diana; van der Vleuten, Cees

    2013-01-01

    Teaching communication skills (CS) to residents during clinical practice remains problematic. Direct observation followed by feedback is a powerful way to teach CS in clinical practice. However, little is known about the effect of training on feedback skills in this field. Controlled studies are scarce as well as studies that go beyond…

  18. Effect of Training Japanese L1 Speakers in the Production of American English /r/ Using Spectrographic Visual Feedback

    Science.gov (United States)

    Patten, Iomi; Edmonds, Lisa A.

    2015-01-01

    The present study examines the effects of training native Japanese speakers in the production of American /r/ using spectrographic visual feedback. Within a modified single-subject design, two native Japanese participants produced single words containing /r/ in a variety of positions while viewing live spectrographic feedback with the aim of…

  19. Effects of Peer Feedback on ESL Student Writers at Different Levels of English Proficiency: A Japanese Context

    Science.gov (United States)

    Kamimura, Taeko

    2006-01-01

    A study was conducted to explore the nature and effectiveness of peer feedback in EFL writing classrooms. High- and low-proficient Japanese EFL learners participated in the study where they exchanged comments with peers after receiving training in peer feedback. The two groups were compared in terms of their pre- and post-tests, original drafts…

  20. Effects of Adding On-the-Job Feedback to Conventional Analog Staff Training in a Nursing Home

    Science.gov (United States)

    Arco, Lucius; du Toit, Elaine

    2006-01-01

    The aims of this study were to examine effects of on-the-job feedback after conventional analog staff training and to corroborate earlier findings of competent performance maintained without feedback from others. The study took place in a nursing home with four staff participants and a resident with problem behaviors. A multiple baseline design…

  1. An analysis of a performance feedback system: the effects of timing and feedback, public posting, and praise upon academic performance and peer interaction.

    Science.gov (United States)

    Van Houten, R; Hill, S; Parsons, M

    1975-01-01

    In the first experiment, after establishing baseline composition rates in each classroom, timing (announcing time limits) and feedback (student self-scoring) were introduced followed by the introduction, removal, and reintroduction of public posting of highest scores. Timing and feedback improved story writing performance and public posting of highest scores improved performance even further in both classrooms. Teacher praise produced further improvement in one classroom but had no effect on performance in the other. Changes in on-task behavior paralleled changes in writing rate. Comments made by children concerning their own work or work of their peers were recorded throughout the experiment. Although the baseline rate of performance comments was almost zero, the introduction of each variable markedly increased the rate of performance comments. In the second experiment, baseline rates on reading and language exercises were established in a fifth-grade classroom. The entire performance feedback system was introduced on a multiple baseline across the two behaviors and then removed during the final phase of the experiment. Introducing the system improved performance on both tasks. These results further increased the generality of some of the findings of the previous experiment and of previous research on the efficacy of the experimental package of timing, feedback, public posting, and praise.

  2. The Comparative Effects of Comprehensible Input, Output and Corrective Feedback on the Receptive Acquisition of L2 Vocabulary Items

    Directory of Open Access Journals (Sweden)

    Mohammad Nowbakht

    2015-08-01

    Full Text Available In the present study, the comparative effects of comprehensible input, output and corrective feedback on the receptive acquisition of L2 vocabulary items were investigated. Two groups of beginning EFL learners participated in the study. The control group received comprehensible input only, while the experimental group received input and was required to produce written output. They also received corrective feedback on their lexical errors if any. This could result in the production of modified output. The results of the study indicated that (a the group which produced output and received feedback (if necessary outperformed the group which only received input in the post-test, (b within the experimental group, feedback played a greater role in learners’ better performance than output, (c also a positive correlation between the amount of feedback an individual learner received, and his overall performance in the post-test; and also between the amount of feedback given for a specific word and the correct responses given to its related item in the post-test was found.  The findings of this study provide evidence for the role of output production along with receiving corrective feedback in enhancing L2 processing by drawing further L2 learners’ attention to their output which in turn may result in improving their receptive acquisition of L2 words. Furthermore, as the results suggested, feedback made a more contribution to L2 development than output. Keywords: comprehensible input, output, interaction, corrective feedback, modified output, receptive vocabulary acquisition

  3. Effect of Environmental and Feedback Interventions on Pacing Profiles in Cycling: A Meta-Analysis

    Science.gov (United States)

    Davies, Michael J.; Clark, Bradley; Welvaert, Marijke; Skorski, Sabrina; Garvican-Lewis, Laura A.; Saunders, Philo; Thompson, Kevin G.

    2016-01-01

    In search of their optimal performance athletes will alter their pacing strategy according to intrinsic and extrinsic physiological, psychological and environmental factors. However, the effect of some of these variables on pacing and exercise performance remains somewhat unclear. Therefore, the aim of this meta-analysis was to provide an overview as to how manipulation of different extrinsic factors affects pacing strategy and exercise performance. Only self-paced exercise studies that provided control and intervention group(s), reported trial variance for power output, disclosed the type of feedback received or withheld, and where time-trial power output data could be segmented into start, middle and end sections; were included in the meta-analysis. Studies with similar themes were grouped together to determine the mean difference (MD) with 95% confidence intervals (CIs) between control and intervention trials for: hypoxia, hyperoxia, heat-stress, pre-cooling, and various forms of feedback. A total of 26 studies with cycling as the exercise modality were included in the meta-analysis. Of these, four studies manipulated oxygen availability, eleven manipulated heat-stress, four implemented pre-cooling interventions and seven studies manipulated various forms of feedback. Mean power output (MPO) was significantly reduced in the middle and end sections (p 0.05). Negative feedback improved overall trial MPO and MPO in the middle section of trials (p 0.05). The available data suggests exercise regulation in hypoxia and heat-stress is delayed in the start section of trials, before significant reductions in MPO occur in the middle and end of the trial. Additionally, negative feedback involving performance deception may afford an upward shift in MPO in the middle section of the trial improving overall performance. Finally, performance improvements can be retained when participants are informed of the deception. PMID:27994554

  4. The Effect of Dynamic Written Corrective Feedback on Iranian Elementary Learners’ Writing

    Directory of Open Access Journals (Sweden)

    Amaneh Kamalian

    2014-09-01

    Full Text Available Error correction is probably the most widely used technique for responding to students’ writing. Although many studies have attempted to investigate the efficacy of providing error correction through different types of written corrective feedback (WCF, there has been relatively little research on any one new approach to writing pedagogy in foreign language learning which is called dynamic WCF. The purpose of the current research was to test the effect of WCF on the improvement of writing abilities of EFL learners. Two groups of EFL students who were learning English as a foreign language participated in this study. Both groups (A and B were given treatments. Core components of the treatment included having the students to write a composition every session (twice a week and the teacher providing the students with feedbacks (dynamic WCF or direct WCF on their writing tasks. Group A (n=24 was instructed through dynamic WCF because it was intended to improve L2 writing ability in general by raising linguistic awareness of learners through the error corrections performed by the teacher.  On the other hand, group B (n= 22 received direct WCF on their writings. Four essential characteristics were taken into consideration for the error correction, i.e. feedback needed to be manageable, meaningful, timely and constant. The data obtained for Group A and Group B was analyzed using paired sample test and the results indicated that both groups had improved on their writing abilities. Also, administrating an independent sample T-test the findings revealed that Group A which received dynamic WCF could outperform Group B. Keywords: corrective feedback; dynamic written corrective feedback; direct error correction

  5. Effects of speed bottleneck on traffic flow with feedback control signal

    Science.gov (United States)

    Zhu, Kangli; Bi, Jiantao; Wu, Jianjun; Li, Shubin

    2016-09-01

    Various car-following models (CMs) have been developed to capture the complex characteristics of microscopic traffic flow, among which the coupled map CM can better reveal and reflect various phenomena of practical traffic flow. Capacity change at bottleneck contributes to high-density traffic flow upstream the bottleneck and contains very complex dynamic behavior. In this paper, we analyze the effect of speed bottleneck on the spatial-temporal evolution characteristics of traffic flow, and propose a method to reduce traffic congestion with the feedback control signal based on CM. Simulation results highlight the potential of using the feedback signal to control the stop-and-go wave and furthermore to alleviate the traffic congestion effectively.

  6. The Effect of AGN and SNe Feedback on Star Formation,Reionization and the Near Infrared Background

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Feedback from supernovae (SNe) and from active galactic nuclei (AGN) accom-panies the history of star formation and galaxy evolution. We present an analytic model to explain how and when the SNe and AGN exert their feedback effects on the star formation and galaxy evolution processes. By using SNe and AGN kinetic feedback mechanisms based on the Lambda Cold Dark Matter (LCDM) model, we explore how these feedback mecha-nisms affect the star formation history (SFH), the Near-Infrared Background (NIRB) flux and the cosmological reionization. We find the values of the feedback strengths, ∈AGN =1.0+0.50.3and ∈SN=0.04+0.02-0.02, can provide a reasonable explanation of most of the observational re-suits, and that the AGN feedback effect on star formation history is quite different from the SNe feedback at high redshifts. Our conclusions manifest quantitatively that these feedback effects decrease star formation rate density (SFRD) and the NIRB flux (in 1.4 - 4.0μm), and postpone the time of completion of the cosmological reionization.

  7. Effects of multi-source feedback on developmental plans for leaders of postgraduate medical education

    DEFF Research Database (Denmark)

    Malling, Bente; Bonderup, Thomas; Mortensen, Lene

    2009-01-01

    OBJECTIVES: Multi-source feedback (MSF) is a widely used developmental tool for leaders in organisations including those dealing with health care. This study was performed to examine the effects of an MSF process on developmental plans made by leaders of postgraduate medical education (PGME...... process might in itself lead to development in administrative areas. However, MSF carried through as a single stand-alone procedure was not sufficient to foster plans for the development of leadership performance....

  8. Physical Effects of Distributed PV Generation on California's Distribution System

    CERN Document Server

    Cohen, Michael A

    2015-01-01

    Deployment of high-penetration photovoltaic (PV) power is expected to have a range of effects -- both positive and negative -- on the distribution grid. The magnitude of these effects may vary greatly depending upon feeder topology, climate, PV penetration level, and other factors. In this paper we present a simulation study of eight representative distribution feeders in three California climates at PV penetration levels up to 100\\%, supported by a unique database of distributed PV generation data that enables us to capture the impact of PV variability on feeder voltage and voltage regulating equipment. When comparing the influence of feeder location (i.e. climate) versus feeder type on outcomes, we find that location more strongly influences the incidence of reverse power flow, reductions in peak loading and the presence of voltage excursions. On the other hand, we find that feeder characteristics more strongly influence the magnitude of loss reduction and changes in voltage regulator operations. We find th...

  9. Quantifying the response of climate to changes in land cover : can we separate direct effects from feedbacks in earth system models' outputs?

    Science.gov (United States)

    Devaraju, Narayanappa; de Noblet-Ducoudré, Nathalie

    2016-04-01

    Regional and global climate responses to biophysical effects of land use and land cover changes (LULCC) still largely differ among the models used in the LUCID intercomparison project, despite some constrained protocol (Boisier et al. 2012). de Noblet-Ducoudré et al. (2012) have shown that ~1/3rd of the differences can be attributed to the lack of consistent implementation of land uses in earth system models (ESM), while the remaining 2/3rd result from differences between land-surface models as well as from the climate feedbacks simulated in each ESM. However, to our knowledge, no study has yet tried to i) disentangle direct effects from feedbacks, and ii) see whether regional sensitivity can be assessed rather than the more traditional global one. In this study we focus on the spatially distributed biophysical effects of LULCC. The important contributors to spatially distributed effects are inhomogeneous changes in direct effects (albedo, evapotranspiration efficiency, surface roughness), and their atmospheric feedbacks. Among those feedbacks one can cite changes in air humidity, air temperature, cloud cover, water vapor and planetary boundary layer height. Direct effects from feedbacks are separated by solving the surface energy budget equation. We have first applied this method to quantify regional and global land surface temperature changes in IPSL-CM5 and NCAR CAM5.0 ESMs that have simulated the effects of idealized global deforestation. In IPSL-CM5, direct effects over land south of latitude 20°N are stronger (warming of 2.26 K in JJA and 1.28 K in DJF) when compared to CAM5.0 (cooling of 0.05 K in JJA and 0.06 K in DJF). In contrast, feedbacks over land north of latitude 20°N are stronger in CAM5.0 (cooling of 4.4 K in JJA and 3.9 K in DJF) when compared to IPSL-CM5 (cooling of 1.9 K in JJA and 3.0 K in DJF). However, on average over global land in both the models we find that direct effects (eg. JJA: 0.55 K in IPSL-CM5 and -0.8 K in CAM5.0) are weaker

  10. Extended-bandwidth frequency sweeps of a distributed feedback laser using combined injection current and temperature modulation

    Science.gov (United States)

    Hefferman, Gerald; Chen, Zhen; Wei, Tao

    2017-07-01

    This article details the generation of an extended-bandwidth frequency sweep using a single, communication grade distributed feedback (DFB) laser. The frequency sweep is generated using a two-step technique. In the first step, injection current modulation is employed as a means of varying the output frequency of a DFB laser over a bandwidth of 99.26 GHz. A digital optical phase lock loop is used to lock the frequency sweep speed during current modulation, resulting in a linear frequency chirp. In the second step, the temperature of the DFB laser is modulated, resulting in a shifted starting laser output frequency. A laser frequency chirp is again generated beginning at this shifted starting frequency, resulting in a frequency-shifted spectrum relative to the first recorded data. This process is then repeated across a range of starting temperatures, resulting in a series of partially overlapping, frequency-shifted spectra. These spectra are then aligned using cross-correlation and combined using averaging to form a single, broadband spectrum with a total bandwidth of 510.9 GHz. In order to investigate the utility of this technique, experimental testing was performed in which the approach was used as the swept-frequency source of a coherent optical frequency domain reflectometry system. This system was used to interrogate an optical fiber containing a 20 point, 1-mm pitch length fiber Bragg grating, corresponding to a period of 100 GHz. Using this technique, both the periodicity of the grating in the frequency domain and the individual reflector elements of the structure in the time domain were resolved, demonstrating the technique's potential as a method of extending the sweeping bandwidth of semiconductor lasers for frequency-based sensing applications.

  11. Climate Effects and Feedback Structure Determining Weed Population Dynamics in a Long-Term Experiment

    Science.gov (United States)

    Lima, Mauricio; Navarrete, Luis; González-Andujar, José Luis

    2012-01-01

    Pest control is one of the areas in which population dynamic theory has been successfully applied to solve practical problems. However, the links between population dynamic theory and model construction have been less emphasized in the management and control of weed populations. Most management models of weed population dynamics have emphasized the role of the endogenous process, but the role of exogenous variables such as climate have been ignored in the study of weed populations and their management. Here, we use long-term data (22 years) on two annual weed species from a locality in Central Spain to determine the importance of endogenous and exogenous processes (local and large-scale climate factors). Our modeling study determined two different feedback structures and climate effects in the two weed species analyzed. While Descurainia sophia exhibited a second-order feedback and low climate influence, Veronica hederifolia was characterized by a first-order feedback structure and important effects from temperature and rainfall. Our results strongly suggest the importance of theoretical population dynamics in understanding plant population systems. Moreover, the use of this approach, discerning between the effect of exogenous and endogenous factors, can be fundamental to applying weed management practices in agricultural systems and to controlling invasive weedy species. This is a radical change from most approaches currently used to guide weed and invasive weedy species managements. PMID:22272362

  12. Climate effects and feedback structure determining weed population dynamics in a long-term experiment.

    Science.gov (United States)

    Lima, Mauricio; Navarrete, Luis; González-Andujar, José Luis

    2012-01-01

    Pest control is one of the areas in which population dynamic theory has been successfully applied to solve practical problems. However, the links between population dynamic theory and model construction have been less emphasized in the management and control of weed populations. Most management models of weed population dynamics have emphasized the role of the endogenous process, but the role of exogenous variables such as climate have been ignored in the study of weed populations and their management. Here, we use long-term data (22 years) on two annual weed species from a locality in Central Spain to determine the importance of endogenous and exogenous processes (local and large-scale climate factors). Our modeling study determined two different feedback structures and climate effects in the two weed species analyzed. While Descurainia sophia exhibited a second-order feedback and low climate influence, Veronica hederifolia was characterized by a first-order feedback structure and important effects from temperature and rainfall. Our results strongly suggest the importance of theoretical population dynamics in understanding plant population systems. Moreover, the use of this approach, discerning between the effect of exogenous and endogenous factors, can be fundamental to applying weed management practices in agricultural systems and to controlling invasive weedy species. This is a radical change from most approaches currently used to guide weed and invasive weedy species managements.

  13. Categorical vowel perception enhances the effectiveness and generalization of auditory feedback in human-machine-interfaces.

    Directory of Open Access Journals (Sweden)

    Eric Larson

    Full Text Available Human-machine interface (HMI designs offer the possibility of improving quality of life for patient populations as well as augmenting normal user function. Despite pragmatic benefits, utilizing auditory feedback for HMI control remains underutilized, in part due to observed limitations in effectiveness. The goal of this study was to determine the extent to which categorical speech perception could be used to improve an auditory HMI. Using surface electromyography, 24 healthy speakers of American English participated in 4 sessions to learn to control an HMI using auditory feedback (provided via vowel synthesis. Participants trained on 3 targets in sessions 1-3 and were tested on 3 novel targets in session 4. An "established categories with text cues" group of eight participants were trained and tested on auditory targets corresponding to standard American English vowels using auditory and text target cues. An "established categories without text cues" group of eight participants were trained and tested on the same targets using only auditory cuing of target vowel identity. A "new categories" group of eight participants were trained and tested on targets that corresponded to vowel-like sounds not part of American English. Analyses of user performance revealed significant effects of session and group (established categories groups and the new categories group, and a trend for an interaction between session and group. Results suggest that auditory feedback can be effectively used for HMI operation when paired with established categorical (native vowel targets with an unambiguous cue.

  14. Climate effects and feedback structure determining weed population dynamics in a long-term experiment.

    Directory of Open Access Journals (Sweden)

    Mauricio Lima

    Full Text Available Pest control is one of the areas in which population dynamic theory has been successfully applied to solve practical problems. However, the links between population dynamic theory and model construction have been less emphasized in the management and control of weed populations. Most management models of weed population dynamics have emphasized the role of the endogenous process, but the role of exogenous variables such as climate have been ignored in the study of weed populations and their management. Here, we use long-term data (22 years on two annual weed species from a locality in Central Spain to determine the importance of endogenous and exogenous processes (local and large-scale climate factors. Our modeling study determined two different feedback structures and climate effects in the two weed species analyzed. While Descurainia sophia exhibited a second-order feedback and low climate influence, Veronica hederifolia was characterized by a first-order feedback structure and important effects from temperature and rainfall. Our results strongly suggest the importance of theoretical population dynamics in understanding plant population systems. Moreover, the use of this approach, discerning between the effect of exogenous and endogenous factors, can be fundamental to applying weed management practices in agricultural systems and to controlling invasive weedy species. This is a radical change from most approaches currently used to guide weed and invasive weedy species managements.

  15. Ice Caps and Ice Belts: The Effects of Obliquity on Ice‑Albedo Feedback

    Science.gov (United States)

    Rose, Brian E. J.; Cronin, Timothy W.; Bitz, Cecilia M.

    2017-09-01

    Planetary obliquity determines the meridional distribution of the annual mean insolation. For obliquity exceeding 55°, the weakest insolation occurs at the equator. Stable partial snow and ice cover on such a planet would be in the form of a belt about the equator rather than polar caps. An analytical model of planetary climate is used to investigate the stability of ice caps and ice belts over the widest possible range of parameters. The model is a non-dimensional diffusive Energy Balance Model, representing insolation, heat transport, and ice‑albedo feedback on a spherical planet. A complete analytical solution for any obliquity is given and validated against numerical solutions of a seasonal model in the “deep-water” regime of weak seasonal ice line migration. Multiple equilibria and unstable transitions between climate states (ice-free, Snowball, or ice cap/belt) are found over wide swaths of parameter space, including a “Large Ice-Belt Instability” and “Small Ice-Belt Instability” at high obliquity. The Snowball catastrophe is avoided at weak radiative forcing in two different scenarios: weak albedo feedback and inefficient heat transport (favoring stable partial ice cover), or efficient transport at high obliquity (favoring ice-free conditions). From speculative assumptions about distributions of planetary parameters, three-fourths to four-fifths of all planets with stable partial ice cover should be in the form of Earth-like polar caps.

  16. Developing Sustainable Feedback Practices

    Science.gov (United States)

    Carless, David; Salter, Diane; Yang, Min; Lam, Joy

    2011-01-01

    Feedback is central to the development of student learning, but within the constraints of modularized learning in higher education it is increasingly difficult to handle effectively. This article makes a case for sustainable feedback as a contribution to the reconceptualization of feedback processes. The data derive from the Student Assessment and…

  17. Contextual Interference Effect in Bandwidth and Self-Control Feedback Conditions on Relative and Absolute Timing Learning

    Directory of Open Access Journals (Sweden)

    Amir Shams

    2016-07-01

    Full Text Available This study aims to better understand the effect of practice schedule and feedback providing types. In two separate experiments the contextual interference effect in bandwidth and self-control feedback conditions on relative and absolute timing learning was examined. In experiment I, the effect of contextual interference using bandwidth and self-control feedback on absolute timing learning (parameters was studied. Results in the acquisition test showed the performance of blocked self-control and bandwidth groups were significantly better than other groups (P0.05. In experiment II, the effects of contextual interference with using a bandwidth and self-control feedback on relative timing learning (GMP were studied. . In retention and transfer tests, the performance of random self-control and bandwidth groups was significantly different to the other groups (P<0.05. The performance of self-control feedback groups in both experiments was better than bandwidth feedback groups (P<0.05 in all stages. The results of this study reveal the beneficial effect of self-control feedback on relative timing (GMP rather than absolute timing (parameter learning and supported the theoretical separation of this processes.

  18. EFFECTIVE KNOWLEDGE TESTS AND FEEDBACK IN FUNCTION OF IMPROVING THE STUDENTS’ STUDY

    Directory of Open Access Journals (Sweden)

    Duško Bjelica

    2011-08-01

    Full Text Available One of the most important issues in the project ”National frame of qualifications and quality providing in education”, run by the EU Delegation in Montenegro, is improvement of students’ study through effective knowledge tests and feedbacks. Knowledge tests do not only represent a problem of knowledge evaluation, but they significantly determine instructional design of the teaching process. Process of organisation and structuring of an exam, besides feasibility and applicability aspects, also has educative aspects. The knowledge tests should motivate a student to improve their own education as well as to motivate them to further studying. An exam should not be considered as individual method of knowledge evaluation, but as a procedure that will be pervaded with the educative programme. In that sense, availability of good-quality feedback enables the students to self-correct, and the chosen methods of examination have to provide relevant results

  19. The effect of feedback and reionization on star formation in low-mass dwarf galaxy haloes

    CERN Document Server

    Simpson, Christine M; Johnston, Kathryn V; Smith, Britton D; Mac Low, Mordecai-Mark; Sharma, Sanjib; Tumlinson, Jason

    2012-01-01

    We simulate the evolution of a 10^9 Msun dark matter halo in a cosmological setting with an adaptive-mesh refinement code as an analogue to local low luminosity dwarf irregular and dwarf spheroidal galaxies. The primary goal of our study is to investigate the roles of reionization and supernova feedback in determining the star formation histories of low mass dwarf galaxies. We include a wide range of physical effects, including metal cooling, molecular hydrogen formation and cooling, photoionization and photodissociation from a metagalactic background, a simple prescription for self-shielding, star formation, and a simple model for supernova driven energetic feedback. We carry out simulations excluding each major effect in turn. We find that reionization is primarily responsible for expelling most of the gas in our simulations, but that supernova feedback is required to disperse the dense, cold gas in the core of the halo. Moreover, we show that the timing of reionization can produce an order of magnitude dif...

  20. Two-wavelength pump-probe technique using single distributed feedback laser array to probe gain recovery of an erbium-doped fiber amplifier

    Science.gov (United States)

    Kuroda, Keiji; Yoshikuni, Yuzo

    2017-03-01

    We propose a two-wavelength pump-probe technique to probe the gain recovery characteristics of an erbium-doped fiber amplifier. The two-wavelength pulse pairs are generated through the direct modulation of a single distributed feedback laser array. The proposed technique allows us to measure the wavelength dependence of the recovery time after gain saturation is induced by a signal of the same wavelength.

  1. Audio Feedback to Physiotherapy Students for Viva Voce: How Effective Is "The Living Voice"?

    Science.gov (United States)

    Munro, Wendy; Hollingworth, Linda

    2014-01-01

    Assessment and feedback remains one of the categories that students are least satisfied with within the United Kingdom National Student Survey. The Student Charter promotes the use of various formats of feedback to enhance student learning. This study evaluates the use of audio MP3 as an alternative feedback mechanism to written feedback for…

  2. Differential Effects of Context and Feedback on Orthographic Learning: How Good Is Good Enough?

    Science.gov (United States)

    Martin-Chang, Sandra; Ouellette, Gene; Bond, Linda

    2017-01-01

    In this study, students in Grade 2 read different sets of words under 4 experimental training conditions (context/feedback, isolation/feedback, context/no-feedback, isolation/no-feedback). Training took place over 10 trials, followed by a spelling test and a delayed reading posttest. Reading in context boosted reading accuracy initially; in…

  3. Critical Feedback in Self-Instructional Course: Need, Nature, and Effects.

    Science.gov (United States)

    Roberts, Eric

    An investigation into uses of evaluative feedback in a graduate-level external-studies course in supervision is reported. Methods of presenting feedback are described, utility and clarity of feedback discussed, and the role of feedback in external and traditional instruction compared. Student assessment of the methods utility and the accuracy of…

  4. Effects of Feedback on Collaborative Writing in an Online Learning Environment

    Science.gov (United States)

    Guasch, Teresa; Espasa, Anna; Alvarez, Ibis M.; Kirschner, Paul A.

    2013-01-01

    The need for supporting student writing has received much attention in writing research. One specific type of support is feedback--including peer feedback--on the writing process. Despite the wealth of literature on both feedback and academic writing, there is little empirical evidence on what type of feedback best promotes writing in online…

  5. Audio Feedback to Physiotherapy Students for Viva Voce: How Effective Is "The Living Voice"?

    Science.gov (United States)

    Munro, Wendy; Hollingworth, Linda

    2014-01-01

    Assessment and feedback remains one of the categories that students are least satisfied with within the United Kingdom National Student Survey. The Student Charter promotes the use of various formats of feedback to enhance student learning. This study evaluates the use of audio MP3 as an alternative feedback mechanism to written feedback for…

  6. Effects of vegetation feedback on future climate change over West Africa

    Science.gov (United States)

    Yu, Miao; Wang, Guiling; Pal, Jeremy S.

    2016-06-01

    This study investigates the impact of climate-vegetation interaction on future climate changes over West Africa using a regional climate model with synchronous coupling between climate and natural vegetation, the RegCM4.3.4-CLM-CN-DV. Based on the lateral boundary conditions supplied by MIROC-ESM and CESM under the greenhouse gas Representative Concentration Pathway 8.5, significant increase of vegetation density is projected over the southern part of Sahel, with an increase of leaf area index and a conversion from grass to woody plants around 7-10°N of Sahel. Regardless of whether the model treats vegetation as static or dynamic, it projects an increase of precipitation in eastern Sahel and decrease in the west. The feedback due to projected vegetation change tends to cause a wet signal, enhancing the projected increase or alleviate the decrease of precipitation in JJA in the areas of projected vegetation increase. Its impact is negligible in DJF. Vegetation feedback slightly enhances projected warming in most of West Africa during JJA, but has a significant cooling effect during DJF in regions of strong vegetation changes. Future changes of surface runoff are projected to follow the direction of precipitation changes. While dynamic vegetation feedback enhances the projected increase of soil water content in JJA, it has a drying effect in DJF. The magnitude of projected ET changes is reduced in JJA and increased in DJF due to vegetation dynamics. A high sensitivity of climate projection to dynamic vegetation feedback was found mainly in semiarid areas of West Africa, with little signal in the wet tropics.

  7. [The effectiveness of cavity preparation training using a virtual reality simulation system with or without feedback].

    Science.gov (United States)

    Yasukawa, Yuriko

    2009-06-01

    The aims of this research were to examine the effectiveness of feedback (FB) study of cavity preparation using a virtual reality system (VRS) and to discuss the evidence from an educational standpoint Thirty-nine dental undergraduate students of the fifth grade of Tokyo Medical and Dental University were randomly divided into the FR group and no-FR group (FB group n=21, no-FR group n=18). All subjects of each group performed cavity preparation of class II on the lower left first molar using VRS (DentSim) four times every week (EXO-3). At session EXO, all subjects performed a pre-test to assess their basic skill leve. At sessions EX1 and EX2, the FR group received feedback from the instructor based on a computer-assessment system. The no-FR group practiced their self-judgment without any feedback. At the last session, EX3, the preparation test was administered. All cavity preparations were graded by the VRS. The results showed that the FR group obtained significantly higher scores than the no-FR group, such as total score, outline shape, outline centralization, outline smoothness, wall incline, wall smoothness, proximal clearance, and box width. By session EX2, the FR group tended to spend longer preparation time than the no-FR group, however, at session EX3, there was no difference between both groups. These resdlts confirmed the effectiveness of cavity preparation with feedback study using VRS. It is suggested that this method of learning cavity preparation techniques is suitable for novice undergraduate dental students at the initial stage of cavity preparation practice.

  8. Effects of kinesthetic haptic feedback on standing stability of young healthy subjects and stroke patients.

    Science.gov (United States)

    Afzal, Muhammad Raheel; Byun, Ha-Young; Oh, Min-Kyun; Yoon, Jungwon

    2015-03-13

    Haptic control is a useful therapeutic option in rehabilitation featuring virtual reality interaction. As with visual and vibrotactile biofeedback, kinesthetic haptic feedback may assist in postural control, and can achieve balance control. Kinesthetic haptic feedback in terms of body sway can be delivered via a commercially available haptic device and can enhance the balance stability of both young healthy subjects and stroke patients. Our system features a waist-attached smartphone, software running on a computer (PC), and a dedicated Phantom Omni® device. Young healthy participants performed balance tasks after assumption of each of four distinct postures for 30 s (one foot on the ground; the Tandem Romberg stance; one foot on foam; and the Tandem Romberg stance on foam) with eyes closed. Patient eyes were not closed and assumption of the Romberg stance (only) was tested during a balance task 25 s in duration. An Android application running continuously on the smartphone sent mediolateral (ML) and anteroposterior (AP) tilt angles to a PC, which generated kinesthetic haptic feedback via Phantom Omni®. A total of 16 subjects, 8 of whom were young healthy and 8 of whom had suffered stroke, participated in the study. Post-experiment data analysis was performed using MATLAB®. Mean Velocity Displacement (MVD), Planar Deviation (PD), Mediolateral Trajectory (MLT) and Anteroposterior Trajectory (APT) parameters were analyzed to measure reduction in body sway. Our kinesthetic haptic feedback system was effective to reduce postural sway in young healthy subjects regardless of posture and the condition of the substrate (the ground) and to improve MVD and PD in stroke patients who assumed the Romberg stance. Analysis of Variance (ANOVA) revealed that kinesthetic haptic feedback significantly reduced body sway in both categories of subjects. Kinesthetic haptic feedback can be implemented using a commercial haptic device and a smartphone. Intuitive balance cues were

  9. Effect of ice-albedo feedback on global sensitivity in a one-dimensional radiative-convective climate model

    Science.gov (United States)

    Wang, W.-C.; Stone, P. H.

    1980-01-01

    The feedback between the ice albedo and temperature is included in a one-dimensional radiative-convective climate model. The effect of this feedback on global sensitivity to changes in solar constant is studied for the current climate conditions. This ice-albedo feedback amplifies global sensitivity by 26 and 39%, respectively, for assumptions of fixed cloud altitude and fixed cloud temperature. The global sensitivity is not affected significantly if the latitudinal variations of mean solar zenith angle and cloud cover are included in the global model. The differences in global sensitivity between one-dimensional radiative-convective models and energy balance models are examined. It is shown that the models are in close agreement when the same feedback mechanisms are included. The one-dimensional radiative-convective model with ice-albedo feedback included is used to compute the equilibrium ice line as a function of solar constant.

  10. The Persuasive Effect of Social Network Feedback on Mediated Communication: A Case Study in a Real Organization.

    Science.gov (United States)

    Varotto, Alessandra; Gamberini, Luciano; Spagnolli, Anna; Martino, Francesco; Giovannardi, Isabella

    2016-03-01

    This study focuses on social feedback, namely on information on the outcome of users' online activity indirectly generated by other users, and investigates in a real setting whether it can affect subsequent activity and, if so, whether participants are aware of that. SkyPas, an application that calculates, transmits, and displays social feedback, was embedded in a common instant messaging service (Skype(™)) and used during a 7-week trial by 24 office workers at a large business organization. The trial followed an ABA scheme in which the B phase was the feedback provision phase. Results show that social feedback affects users' communication activity (participation, inward communication, outward communication, and reciprocity), sometimes even after the feedback provision phase. At the same time, users were poorly aware of this effect, showing a discrepancy between self-reported and observational measures. These results are then discussed in terms of design transparency and task compatibility.

  11. The effect of formal feedback sessions on test security for a clinical practice examination using standardized patients.

    Science.gov (United States)

    Furman, G E; Colliver, J A; Galofré, A; Reaka, M A; Robbs, R S; King, A

    1997-01-01

    To determine the effects of formal feedback on test security for a clinical practice examination administered to successive rotations over a year's time. A seven case clinical performance examination was administered to ten rotations of students throughout an academic year in a required Ambulatory Care Clerkship. Three of the cases were developed at Saint Louis University School of Medicine (SLU); four of the cases were developed by the National Board of Medical Examiners (NBME). Immediately following each examination, the examinees participated in a feedback session for just the three SLU cases: checklists were displayed, and details of the cases were discussed. No feedback on the four NBME cases was provided. Student performance in successive rotations on the three cases in which students were given detailed feedback by the faculty was compared with performance on the four cases in which no feedback was given. Data were collected from 119 students. The interaction of case and group was not significant, indicating no difference in the trend over the ten groups between the three cases for which feedback was provided and the four cases for which it was not. The results showed no significant increasing trend over the ten rotation groups for either cases where feedback was given or withheld. The results suggest that the formal feedback sessions did not pose a threat to test security.

  12. THE EFFECT OF WRITTEN CORRECTIVE FEEDBACK ON HIGHER EDUCATION STUDENTS’ WRITING ACCURACY

    Directory of Open Access Journals (Sweden)

    Yustina Priska Kisnanto

    2016-12-01

    Full Text Available Abstract With the higher demand of accuracy on students’ writing in university level, the present study examines the effect of direct and indirect written corrective feedback (WCF on students’ L2 writing accuracy. The study was conducted in a six-week period with 43 Indonesian university student participants majoring IT. The results of the pre- and post-writing tests showed that 1 the writing accuracy improvement of the students receiving direct WCF was statistically significant while the writing accuracy improvement of the students given the indirect WCF treatment was not; 2 the accuracy improvement in the untreatable error rate of the direct WCF group was the most significant compared to all types of error in both WFC student groups. The study concludes that considering the students’ current English proficiency level and learning setting with limited English exposure, written corrective feedback, especially the direct one, helps the university students improve their writing accuracy. Keywords: corrective feedback, L2 writing, higher education

  13. Expectancy Effects in Feedback Processing are Explained Primarily by Time-frequency Delta not Theta.

    Science.gov (United States)

    Watt, Adreanna T M; Bachman, Matthew D; Bernat, Edward M

    2017-08-30

    The roles of outcome valence and expectancy in feedback processing have been investigated as important factors modulating event-related potential (ERP) measures including the feedback negativity (FN) and P300, but results have been inconsistent. Recent work from our group has shown that processes underlying the FN and P300 are better represented as separable processes in the theta (3-7Hz) and delta (0-3Hz) ranges using time-frequency analysis. The current study evaluated the modulation of time-domain FN and P300 and time-frequency theta and delta to outcome valence and expectancy in a gambling feedback task paradigm.Results revealed that the FN was sensitive to valence but not expectancy, and that valence effects were driven by loss-sensitive theta and gain-sensitive delta. Alternatively, the P300 was sensitive to the expectedness of outcomes but only for gain trials, and these expectancy differences were explained by time-frequency delta not theta. These results add to a growing body of research showing that time-frequency measures reflect separable processes underlying time-domain components, where theta is more sensitive to primary task features and less sensitive to secondary features while delta is sensitive to primary and more complex, secondary task features. Copyright © 2017. Published by Elsevier B.V.

  14. Evaluating the effectiveness of an educational and feedback intervention aimed at improving consideration of sex differences in guideline development

    NARCIS (Netherlands)

    Keuken, D.G.; Haafkens, J.A.; Mohrs, J.; Klazinga, N.S.; Bindels, P.J.E.

    2010-01-01

    Objectives To investigate the effect of an educational and feedback intervention to enhance consideration of sex differences in clinical guideline development. Design Preintervention and postintervention questionnaires in intervention and control groups. Content analysis of intervention guidelines a

  15. Effects of ozone-vegetation coupling on surface ozone air quality via biogeochemical and meteorological feedbacks

    Science.gov (United States)

    Sadiq, Mehliyar; Tai, Amos P. K.; Lombardozzi, Danica; Martin, Maria Val

    2017-02-01

    Tropospheric ozone is one of the most hazardous air pollutants as it harms both human health and plant productivity. Foliage uptake of ozone via dry deposition damages photosynthesis and causes stomatal closure. These foliage changes could lead to a cascade of biogeochemical and biogeophysical effects that not only modulate the carbon cycle, regional hydrometeorology and climate, but also cause feedbacks onto surface ozone concentration itself. In this study, we implement a semi-empirical parameterization of ozone damage on vegetation in the Community Earth System Model to enable online ozone-vegetation coupling, so that for the first time ecosystem structure and ozone concentration can coevolve in fully coupled land-atmosphere simulations. With ozone-vegetation coupling, present-day surface ozone is simulated to be higher by up to 4-6 ppbv over Europe, North America and China. Reduced dry deposition velocity following ozone damage contributes to ˜ 40-100 % of those increases, constituting a significant positive biogeochemical feedback on ozone air quality. Enhanced biogenic isoprene emission is found to contribute to most of the remaining increases, and is driven mainly by higher vegetation temperature that results from lower transpiration rate. This isoprene-driven pathway represents an indirect, positive meteorological feedback. The reduction in both dry deposition and transpiration is mostly associated with reduced stomatal conductance following ozone damage, whereas the modification of photosynthesis and further changes in ecosystem productivity are found to play a smaller role in contributing to the ozone-vegetation feedbacks. Our results highlight the need to consider two-way ozone-vegetation coupling in Earth system models to derive a more complete understanding and yield more reliable future predictions of ozone air quality.

  16. Simultaneous control of volumetric light distribution through turbid media using real-time three-dimensional optoacoustic feedback

    CERN Document Server

    Deán-Ben, X Luís; Razansky, Daniel

    2014-01-01

    Focusing light through turbid media presents a highly fascinating challenge in modern biophotonics. The unique capability of optoacoustics for high resolution imaging of light absorption contrast in deep tissues can provide a natural and efficient feedback to control light delivery in scattering medium. While basic feasibility of using optoacoustic readings as a feedback mechanism for wavefront shaping has been recently reported, the suggested approaches may require long acquisition times making them challenging to be translated into realistic tissue environments. In an attempt to significantly accelerate dynamic wavefront shaping capabilities, we present here a feedback-based approach using real-time three-dimensional optoacoustic imaging assisted with genetic-algorithm-based optimization. The new technique offers robust performance in the presence of noisy measurements and can simultaneously control the scattered wave field in an entire volumetric region.

  17. What do you have to know about feedback to learn a language effectively? : Deelproject ‘Met je mond vol Nederlands’

    NARCIS (Netherlands)

    Berghuis, Stephanie

    2017-01-01

    Stephanie Berghuis examined the effect of teachers’ feedback in language learning. With the help of a group of (Syrian) refugees who are learning the Dutch language, Stephanie did research on the effect of feedback on learning a new language, and also on what kind of feedback works best. The student

  18. Feedback and Incentives

    DEFF Research Database (Denmark)

    Eriksson, Tor Viking; Poulsen, Anders; Villeval, Marie Claire

    2009-01-01

    This paper experimentally investigates the impact of different pay schemes and relative performance feedback policies on employee effort. We explore three feedback rules: no feedback on relative performance, feedback given halfway through the production period, and continuously updated feedback. We...... use two pay schemes, a piece rate and a tournament. We find that overall feedback does not improve performance. In contrast to the piece-rate pay scheme there is some evidence of positive peer effects in tournaments since the underdogs almost never quit the competition even when lagging significantly...... behind, and front runners do not slack off. But in both pay schemes relative performance feedback reduces the quality of the low performers' work; we refer to this as a "negative quality peer effect"....

  19. Investigation of Reactivity Feedback Mechanism of Axial and Radial Expansion Effect of Metal-Fueled Sodium-Cooled Fast Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Seong, Seung-Hwan; Choi, Chi-Woong; Jeong, Tae-Kyung; Ha, Gi-Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    The major inherent reactivity feedback models for a ceramic fuel used in a conventional light water reactor are Doppler feedback and moderator feedback. The metal fuel has these two reactivity feedback mechanisms previously mentioned. In addition, the metal fuel has two more reactivity feedback models related to the thermal expansion phenomena of the metal fuel. Since the metal fuel has a good capability to expand according to the temperature changes of the core, two more feedback mechanisms exist. These additional two feedback mechanism are important to the inherent safety of metal fuel and can make metal-fueled SFR safer than oxide-fueled SFR. These phenomena have already been applied to safety analysis on design extended condition. In this study, the effect of these characteristics on power control capability was examined through a simple load change operation. The axial expansion mechanism is induced from the change of the fuel temperature according to the change of the power level of PGSFR. When the power increases, the fuel temperatures in the metal fuel will increase and then the reactivity will decrease due to the axial elongation of the metal fuel. To evaluate the expansion effect, 2 cases were simulated with the same scenario by using MMS-LMR code developed at KAERI. The first simulation was to analyze the change of the reactor power according to the change of BOP power without the reactivity feedback model of the axial and radial expansion of the core during the power transient event. That is to say, the core had only two reactivity feedback mechanism of Doppler and coolant temperature.

  20. Rescue effects in radiobiology: Unirradiated bystander cells assist irradiated cells through intercellular signal feedback

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Zhao, Y. [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Han, W. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Chiu, S.K. [Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Zhu, L. [Office of Admission and Careers Advisory Service, Shenzhen University, Shenzhen 518060 (China); Wu, L. [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Yu, K.N., E-mail: peter.yu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong)

    2011-01-10

    Mammalian cells respond to ionization radiation by sending out extracellular signals to affect non-irradiated neighboring cells, which is referred to as radiation induced bystander effect. In the present paper, we described a phenomenon entitled the 'rescue effects', where the bystander cells rescued the irradiated cells through intercellular signal feedback. The effect was observed in both human primary fibroblast (NHLF) and cancer cells (HeLa) using two-cell co-culture systems. After co-culturing irradiated cells with unirradiated bystander cells for 24 h, the numbers of 53BP1 foci, corresponding to the number of DNA double-strand breaks in the irradiated cells were less than those in the irradiated cells that were not co-cultured with the bystander cells (0.78 {+-} 0.04 foci/cell vs. 0.90 {+-} 0.04 foci/cell) at a statistically significant level. Similarly, both micronucleus formation and extent of apoptosis in the irradiated cells were different at statistically significant levels if they were co-cultured with the bystander cells. Furthermore, it was found that unirradiated normal cells would also reduce the micronucleus formation in irradiated cancer cells. These results suggested that the rescue effects could participate in repairing the radiation-induced DNA damages through a media-mediated signaling feedback, thereby mitigating the cytotoxicity and genotoxicity of ionizing radiation.

  1. The electoral feedback effects of welfare reform in mature European welfare states

    DEFF Research Database (Denmark)

    Arndt, Christoph

    democracy’s core constituency. Using survey data and election studies, the empirical analysis shows that the reforms have been particularly unpopular among social democracy’s core constituency and that these voters now align with competitors that defend core welfare schemes in a credible manner...... electorates as unity. This paper analysis the feedback effects of social policy retrenchment under Third Way social democracy since 1994. The paper argues that Third Way reforms resulted in lasting electoral setback for social democracy since these reforms went against the social policy preferences of social...

  2. Effect of an audit and feedback intervention on hospitalized oncology patients' perception of nurse practitioner care.

    Science.gov (United States)

    Dulko, Dorothy; Mooney, Kathi

    2010-01-01

    Although patient satisfaction has been used traditionally as a measure of excellence, research has suggested that the perception of being well cared for is likely a more promising indicator of quality than satisfaction alone. Expectations, physical environment, communication, participation and involvement, technical competence, and the influence of healthcare organizations are factors that may impair patients' ability to distinguish nursing care from their overall healthcare experience. This study evaluated the effect of a nurse practitioner audit and feedback intervention on hospitalized patients' perception of care.

  3. Comparing the effects of supernovae feedback models on the interstellar medium

    Science.gov (United States)

    Byrne, Lindsey; Christensen, Charlotte; Keller, Benjamin W.

    2017-01-01

    Stellar feedback affects the state of the interstellar medium and plays an important role in the formation of galaxies. However, different ways of modeling that feedback lead to different galaxy morphologies even when using the same initial conditions. We investigated the differences between two models of supernovae feedback, blastwave feedback and superbubble feedback, using a smoothed particle hydrodynamics code to simulate the formation of an isolated galaxy. The two feedback models were compared across three different models of the ISM: primordial cooling, metal-line cooling, and metal-line cooling in addition to molecular hydrogen. The simulations run with metal-line cooling indicate that superbubble feedback creates a greater amount of high-density gas than blastwave feedback does while also regulating star formation more efficiently. Galaxies produced with metal-line cooling or H2 physics created cold, dense gas, and the increased cooling efficiency was also linked to more pronounced spiral structure.

  4. EXPONENTIAL STABILIZATION OF NONUNIFORM TIMOSHENKO BEAM WITH LOCALLY DISTRIBUTED FEEDBACKS%具局部分布反馈控制的非均质Timoshenko梁的指数稳定性

    Institute of Scientific and Technical Information of China (English)

    司守奎

    2000-01-01

    The stabilization of the Timoshenko equation of a nonuniform beam with locally dis-tributed feedbacks is considered. It is proved that the system is exponentially stabilizable. The frequency domain method and the multiplier technique are applied.

  5. An Exploration into Framing Effects and Information Preferences: Implications for the Design of Energy Feedback Interfaces

    Science.gov (United States)

    Taylor-Brown, Peter

    A recent topic in the energy industry involves developing strategies to reduce the necessary peak production capacity of our future electricity infrastructure. One of these strategies is promoting behavioral change among individual energy consumers. An inherent problem with electricity consumption is that electricity is invisible, intangible, and abstract. Interfaces that provide people with useful feedback on their usage can help with understanding and reduction of consumption. These interfaces intend to empower individuals with ability to adopt less wasteful energy consumption behaviors. Skillful HCI design will include attention to informational preferences, and framing effects due to presentation choices. An online questionnaire was utilized to explore this domain, and the results identified design requirements for a home feedback interface. The final dataset contained responses from 36 male and 49 female United States residents. Cost () was perceived as the most useful metric and kW as the least useful. Respondent preference was expressed for lower levels of automation, which was not attributable to distrust of automation. Further, a test of framings effects showed a higher likelihood to change behavior to save 100 dollars per year than 2 per week (U=1248.5, p=0.001). A feedback interface design based on the questionnaire results was used in the second phase of the research. A 2x2x2 factorial design compared the effects of goal-type (specific vs. open-ended), metric-use ( vs. kWh), and visualization (graphical vs. text-only) on user experience, learning and behavior during a consumption reduction task. Results showed that goal-type affects the amount of diagnostic behavior conducted by participants (U=351.0, p=0.001). Goal-type and metric-use independently affect participant belief that they could reduce their consumption in their real home with the same feedback shown in the task, F(df=1,39)=24.77, p=0.001; F(df=1,39)=5.55, p=0.05. In addition, visualization

  6. The Effect of Teacher Attitudes to Individual Students on the Written Feedback Given

    Institute of Scientific and Technical Information of China (English)

    LiuYinghong; LiuYingzhe; ZhangXiaoyan

    2004-01-01

    Providing written feedback to students is one of EFL writing teachers' most important tasks. As teachers, we know experientially that our students grapple not only with a writtencode but also with a linguistic code that is still being acquired,thus they place value on teacher written feedback; also we hope that our students could benefit from our feedback in their

  7. The Effects of Using Peer and Teacher Feedback into Saudi Writing Context

    Science.gov (United States)

    Alhaisoni, Eid; Alzuoud, Khalid

    2012-01-01

    This paper aims to investigate the efficacy of two commonly used techniques of feedback in teaching writing: teachers' feedback and peers' feedback in the Saudi educational context. The study was comprised of 132 Saudi EFL students enrolled at the Department of English in the University of Hai'l. The data collection was carried out through a…

  8. The Effects of Foreign Language Anxiety on EFL Learners' Perceptions of Oral Corrective Feedback

    Science.gov (United States)

    Rassaei, Ehsan

    2015-01-01

    The study reported in this paper explored if learners' perceptions of two types of oral corrective feedback, recasts, and metalinguistic feedback, are influenced by their foreign language anxiety in classrooms. Corrective feedback was provided to English as a foreign language (EFL) learners who were homogeneous with regard to their proficiency…

  9. Excited, Proud, and Accomplished: Exploring the Effects of Feedback Supplemented with Web-Based Peer Benchmarking on Self-Regulated Learning in Marketing Classrooms

    Science.gov (United States)

    Raska, David

    2014-01-01

    This research explores and tests the effect of an innovative performance feedback practice--feedback supplemented with web-based peer benchmarking--through a lens of social cognitive framework for self-regulated learning. The results suggest that providing performance feedback with references to exemplary peer output is positively associated with…

  10. Does feedback help or hinder star formation? The effect of photoionization on star formation in giant molecular clouds

    Science.gov (United States)

    Shima, Kazuhiro; Tasker, Elizabeth J.; Habe, Asao

    2017-05-01

    We investigated the effect of photoionizing feedback inside turbulent star-forming clouds, comparing the resultant star formation in both idealized profiles and more realistic cloud structures drawn from a global galaxy simulation. We performed a series of numerical simulations that compared the effect of star formation alone, photoionization and photoionization plus supernovae feedback. In the idealized cloud, photoionization suppresses gas fragmentation at early times, resulting in the formation of more massive stars and an increase in the star formation efficiency. At later times, the dispersal of the dense gas causes the radiative feedback effect to switch from positive to negative as the star formation efficiency drops. In the cloud extracted from the global simulation, the initial cloud is heavily fragmented prior to the stellar-feedback beginning and is largely structurally unaffected by the late injection of radiation energy. The result is a suppression of the star formation. We conclude that the efficiency of feedback is heavily dependent on the gas structure, with negative feedback dominating when the density is high.

  11. The equilibrium structure of cosmological halos and the effects of feedback on cosmological structure formation

    Science.gov (United States)

    Iliev, Ilian Tzankov

    observations. TIS reproduces many of the average properties of halos in simulations of the Cold Dark Matter (CDM) model to good accuracy, suggesting it is a useful analytical approximation for halos which form from realistic initial conditions. It matches the density profiles of halos found in CDM N-body simulations outside the innermost region, while avoiding the steep central cusp of the latter which is in apparent conflict with observations. Based on the TIS we also predict the virial temperature and integrated mass distribution of the X-ray clusters formed in the CDM model as found by detailed, 3D, numerical gas and N-body dynamical simulations remarkably well. Our model may also be relevant to nonstandard CDM models, like self-interacting dark matter, recently proposed to resolve this conflict. A possible solution to the problems of the standard CDM model which does not require modification of the microscopic nature of the dark matter is to take proper account of the gasdynamical effects, including feedback caused by energy release during the process of structure formation. Such effects are of particular importance during the reionization of the universe by the first objects that form out of the expanding background. We study the effects of external ionizing radiation on the collapse of cosmological pancakes. We also investigate the effects and observational signatures of ionization fronts during reionization which sweep through the intergalactic medium and photoevaporate cosmological minihalos they encounter.

  12. Annotation an effective device for student feedback: a critical review of the literature.

    Science.gov (United States)

    Ball, Elaine C

    2010-05-01

    The paper examines hand-written annotation, its many features, difficulties and strengths as a feedback tool. It extends and clarifies what modest evidence is in the public domain and offers an evaluation of how to use annotation effectively in the support of student feedback [Marshall, C.M., 1998a. The Future of Annotation in a Digital (paper) World. Presented at the 35th Annual GLSLIS Clinic: Successes and Failures of Digital Libraries, June 20-24, University of Illinois at Urbana-Champaign, March 24, pp. 1-20; Marshall, C.M., 1998b. Toward an ecology of hypertext annotation. Hypertext. In: Proceedings of the Ninth ACM Conference on Hypertext and Hypermedia, June 20-24, Pittsburgh Pennsylvania, US, pp. 40-49; Wolfe, J.L., Nuewirth, C.M., 2001. From the margins to the centre: the future of annotation. Journal of Business and Technical Communication, 15(3), 333-371; Diyanni, R., 2002. One Hundred Great Essays. Addison-Wesley, New York; Wolfe, J.L., 2002. Marginal pedagogy: how annotated texts affect writing-from-source texts. Written Communication, 19(2), 297-333; Liu, K., 2006. Annotation as an index to critical writing. Urban Education, 41, 192-207; Feito, A., Donahue, P., 2008. Minding the gap annotation as preparation for discussion. Arts and Humanities in Higher Education, 7(3), 295-307; Ball, E., 2009. A participatory action research study on handwritten annotation feedback and its impact on staff and students. Systemic Practice and Action Research, 22(2), 111-124; Ball, E., Franks, H., McGrath, M., Leigh, J., 2009. Annotation is a valuable tool to enhance learning and assessment in student essays. Nurse Education Today, 29(3), 284-291]. Although a significant number of studies examine annotation, this is largely related to on-line tools and computer mediated communication and not hand-written annotation as comment, phrase or sign written on the student essay to provide critique. Little systematic research has been conducted to consider how this latter form

  13. Solution of the neutron point kinetics equations with temperature feedback effects applying the polynomial approach method

    Energy Technology Data Exchange (ETDEWEB)

    Tumelero, Fernanda, E-mail: fernanda.tumelero@yahoo.com.br [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica; Petersen, Claudio Z.; Goncalves, Glenio A.; Lazzari, Luana, E-mail: claudiopeteren@yahoo.com.br, E-mail: gleniogoncalves@yahoo.com.br, E-mail: luana-lazzari@hotmail.com [Universidade Federal de Pelotas (DME/UFPEL), Capao do Leao, RS (Brazil). Instituto de Fisica e Matematica

    2015-07-01

    In this work, we present a solution of the Neutron Point Kinetics Equations with temperature feedback effects applying the Polynomial Approach Method. For the solution, we consider one and six groups of delayed neutrons precursors with temperature feedback effects and constant reactivity. The main idea is to expand the neutron density, delayed neutron precursors and temperature as a power series considering the reactivity as an arbitrary function of the time in a relatively short time interval around an ordinary point. In the first interval one applies the initial conditions of the problem and the analytical continuation is used to determine the solutions of the next intervals. With the application of the Polynomial Approximation Method it is possible to overcome the stiffness problem of the equations. In such a way, one varies the time step size of the Polynomial Approach Method and performs an analysis about the precision and computational time. Moreover, we compare the method with different types of approaches (linear, quadratic and cubic) of the power series. The answer of neutron density and temperature obtained by numerical simulations with linear approximation are compared with results in the literature. (author)

  14. Effect of failure/success feedback and the moderating influence of personality on reward motivation.

    Science.gov (United States)

    Anand, Deepika; Oehlberg, Katherine A; Treadway, Michael T; Nusslock, Robin

    2016-01-01

    While motivation to pursue goals is often assumed to be a trait-like characteristic, it is influenced by a variety of situational factors. In particular, recent experiences of success or failure, as well as cognitive responses to these outcomes, may shape subsequent willingness to expend effort for future rewards. To date, however, these effects have not been explicitly tested. In the present study, 131 healthy individuals received either failure or success feedback on a cognitive task. They were then instructed to either ruminate or distract themselves from their emotions. Finally, they completed the Effort Expenditure for Rewards Task, a laboratory measure of reward motivation. Results indicate that participants who received failure feedback relied more strongly on the reward magnitude when choosing whether to exert greater effort to obtain larger rewards, though this effect only held under conditions of significant uncertainty about whether the effort would be rewarded. Further, participants with high levels of trait inhibition were less responsive to reward value and probability when choosing whether to expend greater effort, results that echo past studies of effort-based decision-making in psychological disorders.

  15. Effect of the loss of auditory feedback on segmental parameters of vowels of postlingually deafened speakers.

    Science.gov (United States)

    Schenk, Barbara S; Baumgartner, Wolf Dieter; Hamzavi, Jafar Sasan

    2003-12-01

    The most obvious and best documented changes in speech of postlingually deafened speakers are the rate, fundamental frequency, and volume (energy). These changes are due to the lack of auditory feedback. But auditory feedback affects not only the suprasegmental parameters of speech. The aim of this study was to determine the change at the segmental level of speech in terms of vowel formants. Twenty-three postlingually deafened and 18 normally hearing speakers were recorded reading a German text. The frequencies of the first and second formants and the vowel spaces of selected vowels in word-in-context condition were compared. All first formant frequencies (F1) of the postlingually deafened speakers were significantly different from those of the normally hearing people. The values of F1 were higher for the vowels /e/ (418+/-61 Hz compared with 359+/-52 Hz, P=0.006) and /o/ (459+/-58 compared with 390+/-45 Hz, P=0.0003) and lower for /a/ (765+/-115 Hz compared with 851+/-146 Hz, P=0.038). The second formant frequency (F2) only showed a significant increase for the vowel/e/(2016+/-347 Hz compared with 2279+/-250 Hz, P=0.012). The postlingually deafened people were divided into two subgroups according to duration of deafness (shorter/longer than 10 years of deafness). There was no significant difference in formant changes between the two groups. Our report demonstrated an effect of auditory feedback also on segmental features of speech of postlingually deafened people.

  16. Effects of vegetation feedback in modeling the present-day climate over China

    Science.gov (United States)

    Shi, Y.; Wang, G.; Erfanian, A.; Yu, M.

    2016-12-01

    Abstract: Proper representation of climate-vegetation interactions is important for realistic simulations of the present climate and reliable projections of the future, and dynamic vegetation is being incorporated into more and more climate models. However, coupled vegetation-climate modeling at the regional scale is still at a very early stage. Specifically, very few studies on climate over Asia have accounted for the role of dynamic vegetation feedback. In this study, the regional climate model RegCM version 4.3.4 (RCM) coupled with the Community Land Model version 4/4.5 (CLM) including models of carbon-nitrogen dynamics (CN) and vegetation dynamics (DV) is used to simulate the present day climate over China, and the role of vegetation feedback at different time scales is investigated based on a set of simulations with different treatments of vegetation. Three simulations are conducted, each using RCM-CLM, RCM-CLM-CN, and RCM-CLM-CN-DV respectively, and all simulations are driven with reanalysis data during the period of 1989 to 2009. This presentation will document the model performance in simulating vegetation and climate, and examine the role of vegetation dynamics in climate variability at different time scales. Preliminary results indicate that, when the carbon-nitrogen dynamics and dynamic vegetation feedback are included, the spatial pattern of biases remains similar, but the magnitude of the biases become larger. Model performance in simulating other aspects of the present-day climate will be examined, and the implication of this effect will be studied.

  17. Effects of information feedback on an asymmetrical two-route scenario

    Institute of Scientific and Technical Information of China (English)

    SUN XiaoYan; WANG BingHong; YANG HanXin; WANG QiaoMing; JIANG Rui

    2009-01-01

    In traffic system,a reasonable information feedback can improve road capacity. In this paper,we investigate an asymmetrical two-route scenario in which dynamic information can be generated and displayed on the board to guide drivers. Two improved feedbacks (i.e. improved mean velocity feedback and improved congestion coefficient feedback) are introduced. Simulations show that the average cost is dependent on the vehicle arrival rate and there exists a critical the dynamic vehicles ratio corresponding to the maximum flux. We find that improved con-gestion coefficient can better enhance the system capacity than that of improved mean velocity feedback.

  18. Examining the effects of adult and peer mediated goal setting and feedback interventions for writing: Two studies.

    Science.gov (United States)

    Alitto, Julianna; Malecki, Christine K; Coyle, Samantha; Santuzzi, Alecia

    2016-06-01

    The current study investigated the effects of goal setting and performance feedback on Curriculum Based Measurement in Written Expression (CBM-WE). This two-study investigation examined the utility of the intervention using two different delivery mechanisms. In Study 1, fourth grade students (n=114) were provided both with (a) feedback from their teachers regarding their performance on CBM-WE probes and (b) new weekly goals or no feedback and goals, once a week for a ten-week intervention period. Study 2 examined the effects of this intervention with a sample of fifth grade students (n=106) when feedback and individual goals were provided by peers within their classrooms twice weekly over the course of eight weeks compared to a practice only control condition. Results in both studies indicated that students receiving the goal setting and feedback intervention performed significantly higher on production-dependent writing indices post-intervention than control groups (ES=.12-.28). Implications regarding the usefulness of goal setting and feedback utilizing CBM procedures are discussed.

  19. Pulse Wavelength Scan of Room-Temperature Mid-Infrared Distributed Feedback Quantum Cascade Lasers for N2O Gas Detection

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong-Gang; XU Gang-Yi; LI Ai-Zhen; LI Yao-Yao; GU Yi; LIU Sheng; WEI Lin

    2006-01-01

    @@ The tunable diode laser absorption spectroscopy under a pulse wavelength scan scheme is adapted to home-made room-temperature mid-infrared distributed feedback quantum cascade lasers; and identification of N2 O spectral fingerprint is demonstrated experimentally. By driving the laser at 800ns pulse duration, a wave number tuning of about 1.6 cm- 1 is produced, which make both 1289.04 cm- 1 and 1289.86 cm- 1 absorption fingerprints of N2 O gas to be definitely assigned. The measured relative absorption intensity is consistent with the HITRAN data precisely.

  20. Multi-electrode laterally coupled distributed feedback InGaAsP/InP lasers: a prescription for longitudinal mode control

    Science.gov (United States)

    Benhsaien, Abdessamad; Dridi, Kais; Zhang, Jessica; Hall, Trevor J.

    2013-10-01

    Photonic Integrated Circuits (PICs) enable photons as data carriers at a very high speed. PIC market opportunities call for reduced wafer dimensions, power consumption and cost as well as enhanced reliability. The PIC technology development must cater for the latter relentless traits. In particular, monolithic PICs are sought as they can integrate hundreds of components and functions onto a single chip. InGaAsP/InP laterally-coupled distributed feedback (LC-DFB) lasers stand as key enablers in the PIC technology thanks to the compelling advantages their embedded high-order surface-gratings have. The patterning of the spatial corrugation along the sidewalls of the LC-DFB ridge, has been established to make the epitaxial overgrowth unnecessary thereby reducing the cost and time of manufacturing, and ultimately increasing the yield. LC-DFBs boast a small footprint synonymous of enhanced monolithic integrate-ability. Nonetheless, LC-DFBs suffer from the adverse longitudinal spatial hole burning (LSHB) effects materialized by typically quite high threshold current levels. Indeed, the carrier density longitudinal gradient- responsible for modes contending for the available material gain in the cavity- may be alleviated somewhat by segmenting the LC-DFB electrode into two or three reasonably interspaced longitudinal sections. In this work we report on the realization and performance of various electrode partition configurations. At room temperature, the experimental characterization of many as-cleaved LC-DFB devices provides ample evidence of superior performance such as a narrow linewidth (less than 400 kHz), a wide wavelength tune-ability (over 4 nm) and a hop-free single mode emission (side mode suppression ratio (SMSR) exceeding 54dB).