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Sample records for adaptive gain modulation

  1. Intrinsic gain modulation and adaptive neural coding

    CERN Document Server

    Hong, Sungho; Fairhall, Adrienne

    2008-01-01

    In many cases, the computation of a neural system can be reduced to a receptive field, or a set of linear filters, and a thresholding function, or gain curve, which determines the firing probability; this is known as a linear/nonlinear model. In some forms of sensory adaptation, these linear filters and gain curve adjust very rapidly to changes in the variance of a randomly varying driving input. An apparently similar but previously unrelated issue is the observation of gain control by background noise in cortical neurons: the slope of the firing rate vs current (f-I) curve changes with the variance of background random input. Here, we show a direct correspondence between these two observations by relating variance-dependent changes in the gain of f-I curves to characteristics of the changing empirical linear/nonlinear model obtained by sampling. In the case that the underlying system is fixed, we derive relationships relating the change of the gain with respect to both mean and variance with the receptive fi...

  2. Adaptive gain modulation in V1 explains contextual modifications during bisection learning.

    Directory of Open Access Journals (Sweden)

    Roland Schäfer

    2009-12-01

    Full Text Available The neuronal processing of visual stimuli in primary visual cortex (V1 can be modified by perceptual training. Training in bisection discrimination, for instance, changes the contextual interactions in V1 elicited by parallel lines. Before training, two parallel lines inhibit their individual V1-responses. After bisection training, inhibition turns into non-symmetric excitation while performing the bisection task. Yet, the receptive field of the V1 neurons evaluated by a single line does not change during task performance. We present a model of recurrent processing in V1 where the neuronal gain can be modulated by a global attentional signal. Perceptual learning mainly consists in strengthening this attentional signal, leading to a more effective gain modulation. The model reproduces both the psychophysical results on bisection learning and the modified contextual interactions observed in V1 during task performance. It makes several predictions, for instance that imagery training should improve the performance, or that a slight stimulus wiggling can strongly affect the representation in V1 while performing the task. We conclude that strengthening a top-down induced gain increase can explain perceptual learning, and that this top-down signal can modify lateral interactions within V1, without significantly changing the classical receptive field of V1 neurons.

  3. Receiver Gain Modulation Circuit

    Science.gov (United States)

    Jones, Hollis; Racette, Paul; Walker, David; Gu, Dazhen

    2011-01-01

    A receiver gain modulation circuit (RGMC) was developed that modulates the power gain of the output of a radiometer receiver with a test signal. As the radiometer receiver switches between calibration noise references, the test signal is mixed with the calibrated noise and thus produces an ensemble set of measurements from which ensemble statistical analysis can be used to extract statistical information about the test signal. The RGMC is an enabling technology of the ensemble detector. As a key component for achieving ensemble detection and analysis, the RGMC has broad aeronautical and space applications. The RGMC can be used to test and develop new calibration algorithms, for example, to detect gain anomalies, and/or correct for slow drifts that affect climate-quality measurements over an accelerated time scale. A generalized approach to analyzing radiometer system designs yields a mathematical treatment of noise reference measurements in calibration algorithms. By treating the measurements from the different noise references as ensemble samples of the receiver state, i.e. receiver gain, a quantitative description of the non-stationary properties of the underlying receiver fluctuations can be derived. Excellent agreement has been obtained between model calculations and radiometric measurements. The mathematical formulation is equivalent to modulating the gain of a stable receiver with an externally generated signal and is the basis for ensemble detection and analysis (EDA). The concept of generating ensemble data sets using an ensemble detector is similar to the ensemble data sets generated as part of ensemble empirical mode decomposition (EEMD) with exception of a key distinguishing factor. EEMD adds noise to the signal under study whereas EDA mixes the signal with calibrated noise. It is mixing with calibrated noise that permits the measurement of temporal-functional variability of uncertainty in the underlying process. The RGMC permits the evaluation of EDA by

  4. Adaptive Digital Calibration of Amplifier Finite Gain Effects and C-ratio Matching Errors for MASH Modulators

    Institute of Scientific and Technical Information of China (English)

    Feng Hui(冯晖); Lin Zhenghui

    2004-01-01

    Cascaded sigma-delta (MASH) modulators for higher order oversampled analog-to-digital conversion rely on precise matching of contributions from different quantizers to cancel lower order quantization noise from intermediate delta-sigma stages. This paper studies the effect of analog imperfections in the implementation, such as finite gain of the amplifiers and capacitor ratio mismatch, and presents an adaptive algorithm and implementation architectures for digital correction of such analog imperfections. Behavioral simulations on 1-1-1 oversampled converters demonstrate over 10dB improvements in signal-to-noise and over 20 dB improvements in dynamic range performance.

  5. Reward-driven modulation of adaptive control: How prospective monetary gains interact with unpredictable control demands

    NARCIS (Netherlands)

    Marien, Hans; Aarts, Henk; Custers, Ruud

    2014-01-01

    Shifting attention is an effortful control process and incurs a cost on the cognitive system. Previous research suggests that rewards, such as monetary gains, will selectively enhance the ability to shift attention when this demand for control is explicitly cued. Here, we hypothesized that prospecti

  6. Robust Optimal Adaptive Control Method with Large Adaptive Gain

    Science.gov (United States)

    Nguyen, Nhan T.

    2009-01-01

    In the presence of large uncertainties, a control system needs to be able to adapt rapidly to regain performance. Fast adaptation is referred to the implementation of adaptive control with a large adaptive gain to reduce the tracking error rapidly. However, a large adaptive gain can lead to high-frequency oscillations which can adversely affect robustness of an adaptive control law. A new adaptive control modification is presented that can achieve robust adaptation with a large adaptive gain without incurring high-frequency oscillations as with the standard model-reference adaptive control. The modification is based on the minimization of the Y2 norm of the tracking error, which is formulated as an optimal control problem. The optimality condition is used to derive the modification using the gradient method. The optimal control modification results in a stable adaptation and allows a large adaptive gain to be used for better tracking while providing sufficient stability robustness. Simulations were conducted for a damaged generic transport aircraft with both standard adaptive control and the adaptive optimal control modification technique. The results demonstrate the effectiveness of the proposed modification in tracking a reference model while maintaining a sufficient time delay margin.

  7. Adaptive Human Control Gains During Precision Grip

    Directory of Open Access Journals (Sweden)

    Erik D. Engeberg

    2013-03-01

    Full Text Available Eight human test subjects attempted to track a desired position trajectory with an instrumented manipulandum (MN. The test subjects used the MN with three different levels of stiffness. A transfer function was developed to represent the human application of a precision grip from the data when the test subjects initially displaced the MN so as to learn the position mapping from the MN onto the display. Another transfer function was formed from the data of the remainder of the experiments, after significant displacement of the MN occurred. Both of these transfer functions accurately modelled the system dynamics for a portion of the experiments, but neither was accurate for the duration of the experiments because the human grip dynamics changed while learning the position mapping. Thus, an adaptive system model was developed to describe the learning process of the human test subjects as they displaced the MN in order to gain knowledge of the position mapping. The adaptive system model was subsequently validated following comparison with the human test subject data. An examination of the average absolute error between the position predicted by the adaptive model and the actual experimental data yielded an overall average error of 0.34mm for all three levels of stiffness.

  8. Attention modulates visual size adaptation.

    OpenAIRE

    Kreutzer, Sylvia; Fink, G R; R. Weidner

    2015-01-01

    The current study determined in healthy subjects (n = 16) whether size adaptation occurs at early, i.e., preattentive, levels of processing or whether higher cognitive processes such as attention can modulate the illusion. To investigate this issue, bottom-up stimulation was kept constant across conditions by using a single adaptation display containing both small and large adapter stimuli. Subjects' attention was directed to either the large or small adapter stimulus by means of a luminance ...

  9. A Unified Approach to High-Gain Adaptive Controllers

    Directory of Open Access Journals (Sweden)

    Ian A. Gravagne

    2009-01-01

    Full Text Available It has been known for some time that proportional output feedback will stabilize MIMO, minimum-phase, linear time-invariant systems if the feedback gain is sufficiently large. High-gain adaptive controllers achieve stability by automatically driving up the feedback gain monotonically. More recently, it was demonstrated that sample-and-hold implementations of the high-gain adaptive controller also require adaptation of the sampling rate. In this paper, we use recent advances in the mathematical field of dynamic equations on time scales to unify and generalize the discrete and continuous versions of the high-gain adaptive controller. We prove the stability of high-gain adaptive controllers on a wide class of time scales.

  10. Reward Modulates Adaptations to Conflict

    Science.gov (United States)

    Braem, Senne; Verguts, Tom; Roggeman, Chantal; Notebaert, Wim

    2012-01-01

    Both cognitive conflict (e.g. Verguts & Notebaert, 2009) and reward signals (e.g. Waszak & Pholulamdeth, 2009) have been proposed to enhance task-relevant associations. Bringing these two notions together, we predicted that reward modulates conflict-based sequential adaptations in cognitive control. This was tested combining either a single…

  11. Context-specific adaptation of saccade gain in parabolic flight

    Science.gov (United States)

    Shelhamer, Mark; Clendaniel, Richard A.; Roberts, Dale C.

    2002-01-01

    Previous studies established that vestibular reflexes can have two adapted states (e.g., gains) simultaneously, and that a context cue (e.g., vertical eye position) can switch between the two states. Our earlier work demonstrated this phenomenon of context-specific adaptation for saccadic eye movements: we asked for gain decrease in one context state and gain increase in another context state, and then determined if a change in the context state would invoke switching between the adapted states. Horizontal and vertical eye position and head orientation could serve, to varying degrees, as cues for switching between two different saccade gains. In the present study, we asked whether gravity magnitude could serve as a context cue: saccade adaptation was performed during parabolic flight, which provides alternating levels of gravitoinertial force (0 g and 1.8 g). Results were less robust than those from ground experiments, but established that different saccade magnitudes could be associated with different gravity levels.

  12. Research on Threshold Adjustment Algorithm in Adaptive Modulation and Coding

    Institute of Scientific and Technical Information of China (English)

    FAN Chen; CHEN Mei-ya; SU Li-jun; YANG Da-cheng

    2006-01-01

    Adaptive Modulation and Coding (AMC) has gained a lot of attentions in the research of High Speed Downlink Packet Access (HSDPA). The idea is to adapt the transmission to the fast changing channel conditions by the use of different Modulation and Coding Schemes (MCS). This paper presents an adaptive AMC algorithm and introduces a theoretical analysis model in order to to investigate its throughput and Frame Error Rate (FER). Subject to the given FER target, our numerical and link level simulation results both show that our algorithm outperforms other existing adaptive algorithms.

  13. Lunar Module 5 mated with Spacecraft Lunar Module Adapter (SLA)

    Science.gov (United States)

    1969-01-01

    Interior view of the Kennedy Space Center's (KSC) Manned Spacecraft Operations Building showing Lunar Module 5 mated to its Spacecraft Lunar Module Adapter (SLA). LM-5 is scheduled to be flown on the Apollo 11 lunar landing mission.

  14. The adaptive-loop-gain adaptive-scale CLEAN deconvolution of radio interferometric images

    CERN Document Server

    Zhang, L; Liu, X

    2016-01-01

    CLEAN algorithms are a class of deconvolution solvers which are widely used to remove the effect of the telescope Point Spread Function (PSF). Loop gain is one important parameter in CLEAN algorithms. Currently the parameter is fixed during deconvolution, which restricts the performance of CLEAN algorithms. In this paper, we propose a new deconvolution algorithm with an adaptive loop gain scheme, which is referred to as the adaptive-loop-gain adaptivescale CLEAN (Algas-Clean) algorithm. The test results show that the new algorithm can give a more accurate model with faster convergence.

  15. Divisive gain modulation of motoneurons by inhibition optimizes muscular control.

    Science.gov (United States)

    Vestergaard, Mikkel; Berg, Rune W

    2015-02-25

    When using muscles, the precision with which force is delivered is as important as the delivery of force itself. Force is regulated by both the number of recruited motoneurons and their spike frequency. While it is known that the recruitment is ordered to reduce variability in force, it remains unclear whether the motoneuron gain, i.e., the slope of the transformation between synaptic input and spiking output, is also modulated to reduce variability in force. To address this issue, we use turtle hindlimb scratching as a model for fine motor control, since this behavior involves precise limb movement to rub the location of somatic nuisance touch. We recorded intracellularly from motoneurons in a reduced preparation where the limbs were removed to increase mechanical stability and the motor nerve activity served as a surrogate for muscle force. We found that not only is the gain of motoneurons regulated on a subsecond timescale, it is also adjusted to minimize variability. The modulation is likely achieved via an expansive nonlinearity between spike rate and membrane potential with inhibition having a divisive influence. These findings reveal a versatile mechanism of modulating neuronal sensitivity and suggest that such modulation is fundamentally linked to optimization.

  16. Pragmatic Approach to Adaptive Turbo Coded Modulation

    Institute of Scientific and Technical Information of China (English)

    左健存; 宋文涛; 罗汉文; 徐友云

    2003-01-01

    This paper presents a pragmatic adaptive scheme for TuCM over slowly fading channels. The adaptive scheme employs a single turbo coded modulator composed of a variable-rate turbo encoder and a variable-rate variable-power MQAM for all fading regions, so it has an acceptable complexity to implement. The optimal adaptive TuCM scheme is determined subject to various system constraints. Simulations have been performed to measure the performance of the scheme for different parameters. It is shown that adopting both the turbo coded modulator and the transmit power achieves a performance within 2.5 dB of the fading channel capacity.

  17. OPTICAL WAVELENGTH CONVERTERS BASED ON CROSS GAIN MODULATION AND CROSS PHASE MODULATION IN SOA

    Directory of Open Access Journals (Sweden)

    Vikas Thakur

    2012-06-01

    Full Text Available All optical wavelength conversion is demonstrated at 10 Gbit/s over a wavelength span of 10 nm without any bit loss by the use of Semiconductor Optical Amplifier (SOA in a Mach-Zehnder configuration. These wavelength conversion architectures are implemented by using SOA cross-gain modulation (XGM and cross-phase modulation (XPM techniques. We have compared the results of both techniques on the basics of Bit Error Rate (BER and Quality factor.

  18. MULTICARRIER DS-CDMA WITH ADAPTIVE MODULATION AND POWER ALLOCATION

    Institute of Scientific and Technical Information of China (English)

    Zhao Yahong; Zhang Zhongpei; Wu Weiling

    2003-01-01

    Adaptive modulation and power allocation is introduced into the multicarrier DS-CDMA system to improve the system performance and bandwidth efficiency. First, the systemdesign appropriate for adaptive modulation and power allocation is given, then the algorithmof adaptive modulation and power allocation is applied. Simulation results demonstrate greatperformance improvement compared with the fixed modulated one.

  19. Analysis of small-signal intensity modulation of semiconductor lasers taking account of gain suppression

    Indian Academy of Sciences (India)

    Moustafa Ahmed; Ali El-Lafi

    2008-07-01

    This paper demonstrates theoretical characterization of intensity modulation of semiconductor lasers (SL’s). The study is based on a small-signal model to solve the laser rate equations taking into account suppression of optical gain. Analytical forms of the small-signal modulation response and modulation bandwidth are derived. Influences of the bias current, modulation index and modulation frequency as well as gain suppression on modulation characteristics are examined. Computer simulation of the model is applied to 1.55-m InGaAsP lasers. The results show that when the SL is biased far-above threshold, the increase of gain suppression increases both the modulation response and its peak frequency. The modulation bandwidth also increases but the laser damping rate decreases. Quantitative description of the relationships of both modulation bandwidth vs. relaxation frequency and maximum modulation bandwidth vs. nonlinear gain coefficient are presented.

  20. SiPM Gain Stabilization Studies for Adaptive Power Supply

    CERN Document Server

    AUTHOR|(CDS)2074257; Zalieckas, Justas; Cvach, Jaroslav; Kvasnicka, Jiri; Polak, Ivo

    2016-01-01

    We present herein gain stabilization studies of SiPMs using a climate chamber at CERN. We present results for four detectors not tested before, three from Hamamatsu and one from KETEK. Two of the Hamamatsu SiPMs are novel sensors with trenches that reduce cross talk. We use an improved readout system with a digital oscilloscope controlled with a dedicated LabView program. We improved and automized the analysis to deal with large datasets. We have measured the gain-versus-bias-voltage dependence at fixed temperature and gain-versus-temperature dependence at fixed bias voltage to determine the bias voltage dependence on temperature $V(T)$ for stable gain. We show that the gain remains stable to better than $\\pm 0.5\\%$ in the $20^\\circ \\rm C - 30^\\circ C$ temperature range if the bias voltage is properly adjusted with temperature.

  1. Complete modulational-instability gain spectrum of nonlinear quasi-phase-matching gratings

    DEFF Research Database (Denmark)

    Corney, Joel F.; Bang, Ole

    2004-01-01

    We consider plane waves propagating in quadratic nonlinear slab waveguides with nonlinear quasi-phasematching gratings. We predict analytically and verify numerically the complete gain spectrum for transverse modulational instability, including hitherto undescribed higher-order gain bands....

  2. Pump-to-Signal Intensity Modulation Transfer in Saturated- Gain Fiber Optical Parametric Amplifiers

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke; Rottwitt, Karsten;

    2011-01-01

    The pump-to-signal intensity modulation transfer in saturated degenerate FOPAs is numerically investigated over the whole gain bandwidth. The intensity modulation transfer decreases and the OSNR improves when the amplifier operates in the saturation regime....

  3. Seeded Supercontinuum Generation - Modulation Instability Gain, Coherent and Incoherent Rogue Waves

    DEFF Research Database (Denmark)

    Sørensen, Simon Toft; Larsen, Casper; Møller, Uffe Visbech;

    2012-01-01

    Deterministic supercontinuum can be generated by seeding the modulation instability-induced pulse break-up. We investigate the influence of the modulation instability gain on seeding and demonstrate the generation of coherent and incoherent rogue waves.......Deterministic supercontinuum can be generated by seeding the modulation instability-induced pulse break-up. We investigate the influence of the modulation instability gain on seeding and demonstrate the generation of coherent and incoherent rogue waves....

  4. Cognitive adaptation of sonar gain control in the bottlenose dolphin.

    Science.gov (United States)

    Kloepper, Laura N; Smith, Adam B; Nachtigall, Paul E; Buck, John R; Simmons, James A; Pacini, Aude F

    2014-01-01

    Echolocating animals adjust the transmit intensity and receive sensitivity of their sonar in order to regulate the sensation level of their echoes; this process is often termed automatic gain control. Gain control is considered not to be under the animal's cognitive control, but previous investigations studied animals ensonifying targets or hydrophone arrays at predictable distances. To test whether animals maintain gain control at a fixed level in uncertain conditions, we measured changes in signal intensity for a bottlenose dolphin (Tursiops truncatus) detecting a target at three target distances (2.5, 4 and 7 m) in two types of sessions: predictable and unpredictable. Predictable sessions presented the target at a constant distance; unpredictable sessions moved the target randomly between the three target positions. In the predictable sessions the dolphin demonstrated intensity distance compensation, increasing the emitted click intensity as the target distance increased. Additionally, as trials within sessions progressed, the animal adjusted its click intensity even from the first click in a click train, which is consistent with the animal expecting a target at a certain range. In the unpredictable sessions there was no significant difference of intensity with target distance until after the 7th click in a click train. Together, these results demonstrate that the bottlenose dolphin uses learning and expectation for sonar gain control.

  5. Temporal adaptation enhances efficient contrast gain control on natural images.

    Directory of Open Access Journals (Sweden)

    Fabian Sinz

    Full Text Available Divisive normalization in primary visual cortex has been linked to adaptation to natural image statistics in accordance to Barlow's redundancy reduction hypothesis. Using recent advances in natural image modeling, we show that the previously studied static model of divisive normalization is rather inefficient in reducing local contrast correlations, but that a simple temporal contrast adaptation mechanism of the half-saturation constant can substantially increase its efficiency. Our findings reveal the experimentally observed temporal dynamics of divisive normalization to be critical for redundancy reduction.

  6. ADAPTIVE EXPERT SYSTEM FOR CALCULATION OF REAL EAR INSERTION GAIN FOR DIGITAL HEARING AID

    Directory of Open Access Journals (Sweden)

    Sadagopan Rajkumar

    2013-01-01

    Full Text Available The various gain calculating formulae for digital hearing aids is analyzed for different subjects to find out suitable adaptive gain formula for most successful gain recommendations. The object of the work is to design and develop an adaptive expert system, which could be effectively used to perform screening tests to identify the level of hearing impairment and recommend suitable gain suggestions for frequency bands of digital hearing aid. Initially, the design requirements for a digital hearing aid are being arrived by using the standard gain formulae followed such as National Acoustic Laboratory Revised (NAL-R and Prescription of Gain Output (POGO II. The test is carried with 272 subjects aging from 25 to 72 and 221 male and 51 female. Of which gain is recommended for 127 subjects with the standard gain formula. When the recommendations are verified for satisfaction among the hearing aid users only 28 received satisfaction with NAL-R and 25 received satisfactions with POGO II. Remaining subjects received satisfaction only after fine tuning the gain value and recommended gains are stored in adaptive expert system. Subsequently, based on the suggested value of gains and additional data from expert audiologists, gain formula could be made distinct for every language.

  7. The effects of smooth pursuit adaptation on the gain of visuomotor transmission in monkeys

    Directory of Open Access Journals (Sweden)

    Seiji eOno

    2013-12-01

    Full Text Available Smooth pursuit eye movements are supported by visual-motor systems, where visual motion information is transformed into eye movement commands. Adaptation of the visuomotor systems for smooth pursuit is an important factor to maintain pursuit accuracy and high acuity vision. Short-term adaptation of initial pursuit gain can be produced experimentally using by repeated trials of a step-ramp tracking with two different velocities (double-step paradigm that step-up (10–30 °/s or step-down (20–5 °/s. It is also known that visuomotor gain during smooth pursuit is regulated by a dynamic gain control mechanism by showing that eye velocity evoked by a target perturbation during pursuit increases bidirectionally when ongoing pursuit velocity is higher. However, it remains uncertain how smooth pursuit adaptation alters the gain of visuomotor transmission. Therefore, a single cycle of sinusoidal motion (2.5 Hz, ± 10 °/s was introduced during step-ramp tracking pre- and post-adaptation to determine whether smooth pursuit adaptation affects the perturbation response. The results showed that pursuit adaptation had a significant effect on the perturbation response that was specific to the adapted direction. These results indicate that there might be different visuomotor mechanisms between adaptation and dynamic gain control. Furthermore, smooth pursuit adaptation altered not only the gain of the perturbation response, but also the gain slope (regression curve at different target velocities (5, 10 and 15 °/s. Therefore, pursuit adaptation could affect the dynamic regulation of the visuomotor gain at different pursuit velocities.

  8. Adaptive tuning of feedback gain in time-delayed feedback control

    Science.gov (United States)

    Lehnert, J.; Hövel, P.; Flunkert, V.; Guzenko, P. Yu.; Fradkov, A. L.; Schöll, E.

    2011-12-01

    We demonstrate that time-delayed feedback control can be improved by adaptively tuning the feedback gain. This adaptive controller is applied to the stabilization of an unstable fixed point and an unstable periodic orbit embedded in a chaotic attractor. The adaptation algorithm is constructed using the speed-gradient method of control theory. Our computer simulations show that the adaptation algorithm can find an appropriate value of the feedback gain for single and multiple delays. Furthermore, we show that our method is robust to noise and different initial conditions.

  9. Flexible Joints Robotic Manipulator Control By Adaptive Gain Smooth Sliding Observer-Controller

    Directory of Open Access Journals (Sweden)

    A. FILIPESCU

    2003-12-01

    Full Text Available An adaptive gain sliding observer for uncertain parameter nonlinear systems together with an adaptive gain sliding controller is proposed in this paper. It considered nonlinear, SISO affine systems, with uncertainties in steady-state functions and parameters. A further parameter term, adaptively updated, has been introduced in steady state space model of the controlled system, in order to obtain useful information despite fault detection and isolation. By using of the sliding observer with adaptive gain, the robustness to uncertainties is increased and the parameters adaptively updated can provide useful information in fault detection. Also, the state estimation error is bounded accordingly with bound limits of the uncertainties. The both of them, the sliding adaptive observer and sliding controller are designed to fulfill the attractiveness condition of its corresponding switching surface. An application to a single arm with flexible joint robot is presented. In order to alleviate chattering, a parameterized tangent hyperbolic has been used as switching function, instead of pure relay one, to the observer and the controller. Also, the gains of the switching functions, to the sliding observer and sliding controller are adaptively updated depending of estimation error and tracking error, respectively. By the using adaptive gains, the transient and tracking response can be improved.

  10. Asymmetric Modulation Gains in Network Coded Relay Networks

    DEFF Research Database (Denmark)

    Roetter, Daniel Enrique Lucani; Fitzek, Frank

    2015-01-01

    –to–end throughput by (i) using network coding to control the use of the relay in an effective manner, and (ii) leveraging asymmetric modulation to enable the source to efficiently allocate its resources. We provide mathematical analysis and a simple optimization mechanism. Numerical results for the case of fading...

  11. Gain modulation by graphene plasmons in aperiodic lattice lasers

    Science.gov (United States)

    Chakraborty, S.; Marshall, O. P.; Folland, T. G.; Kim, Y.-J.; Grigorenko, A. N.; Novoselov, K. S.

    2016-01-01

    Two-dimensional graphene plasmon-based technologies will enable the development of fast, compact, and inexpensive active photonic elements because, unlike plasmons in other materials, graphene plasmons can be tuned via the doping level. Such tuning is harnessed within terahertz quantum cascade lasers to reversibly alter their emission. This is achieved in two key steps: first, by exciting graphene plasmons within an aperiodic lattice laser and, second, by engineering photon lifetimes, linking graphene’s Fermi energy with the round-trip gain. Modal gain and hence laser spectra are highly sensitive to the doping of an integrated, electrically controllable, graphene layer. Demonstration of the integrated graphene plasmon laser principle lays the foundation for a new generation of active, programmable plasmonic metamaterials with major implications across photonics, material sciences, and nanotechnology.

  12. Adaptive control of linear multivariable systems with high frequency gain matrix hurwitz

    Institute of Scientific and Technical Information of China (English)

    Ying ZHOU; Yuqiang WU; Shumin FEI

    2005-01-01

    A new adaptive control scheme is proposed for multivariable model reference adaptive control(MRAC) systems based on the nonlinear backstepping approach with vector form.The assumption on a priori knowledge of the high frequency gain matrix in existing results is relaxed and the new required condition for the high frequency gain matrix can be easily checked for certain plants so that the proposed method is widely applicable.This control scheme guarantees the global stability of the closed-loop systems and the tracking error can be arbitrary small.The simulation result for an application example shows the validity of the proposed nonlinear adaptive scheme.

  13. Fuzzy logic based Adaptive Modulation Using Non Data Aided SNR Estimation for OFDM system

    Directory of Open Access Journals (Sweden)

    K.SESHADRI SASTRY

    2010-06-01

    Full Text Available As demand for high quality transmission increases increase of spectrum efficiency and an improvement of error performance in wireless communication systems are important . One of the promising approaches to 4G is adaptive OFDM (AOFDM . Fixed modulation systems uses only one type of modulation scheme (or order, so that either performance or capacity should be compromised Adaptive modulated systems are superior to fixed modulated systems, since they change modulation order depending on present SNR. In an adaptive modulation system SNR estimation is important since performance of adaptive modulated system depends of estimated SNR. Non-data-Aided (NDA SNR estimation systems are gaining importance in recent days since they estimate SNR range and requires less data as input .In this paper we propose an adaptive modulated OFDM system which uses NDA(Non-data Aided SNR estimation using fuzzy logic interface.The proposed system is simulated in Matlab 7.4 and The results of computer simulation show the improvement in system capacity .

  14. 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.

  15. Adaptive modulation for a downlink multicast channel in OFDMA systems

    DEFF Research Database (Denmark)

    Wang, Haibo; Schwefel, Hans-Peter; Toftegaard, Thomas Skjødeberg

    2007-01-01

    In this paper we focus on adaptive modulation strategies for Multicast service in orthogonal frequency division multiple access systems. A Reward function has been defined as the optimization target, which includes both the average user throughput and bit error rate. We also developed an adaptive...... modulation strategy, namely Local Best Reward strategy, to maximize this Reward function. The performance of different modulation strategies are compared in different SNR distribution scenarios, and the optimum strategy in each scenario is suggested....

  16. Plasmonic modulator based on gain-assisted metal-semiconductor-metal waveguide

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia E.; Kulkova, Irina V.; Malureanu, Radu;

    2012-01-01

    We investigate plasmonic modulators with a gain material to be implemented as ultra-compact and ultra-fast active nanodevices in photonic integrated circuits. We analyze metal-semiconductor-metal (MSM) waveguides with InGaAsP-based active material layers as ultra-compact plasmonic modulators....... The modulation is achieved by changing the gain of the core that results in different transmittance through the waveguides. A MSM waveguide enables high field localization and therefore high modulation speed. Bulk semiconductor, quantum wells and quantum dots, arranged in either horizontal or vertical layout......, are considered as the core of the MSM waveguide. Dependences on the waveguide core size and gain values of various active materials are studied. The designs consider also practical aspects like n- and p-doped layers and barriers in order to obtain results as close to reality. The effective propagation constants...

  17. Centroid gain compensation in Shack-Hartmann adaptive optics systems with natural or laser guide star

    Science.gov (United States)

    Veran; Herriot

    2000-08-01

    In an adaptive optics system with an undersampled Shack-Hartmann wave-front sensor (WFS), variations in seeing, laser guide star quality, and sodium layer thickness and range distance all combine to vary WFS centroid gain across the pupil during an exposure. While using the minimum of 4 pixels per WFS subaperture improves frame rate and read noise, the WFS centroid gain uncertainty may introduce static aberrations and degrade servo loop phase margin. We present a novel method to estimate and compensate WFS gains of each subaperture individually in real time for both natural and laser guide stars.

  18. Single gain peak from modulation instability in As2Se3 chalcogenide glass photonic crystal fiber

    Science.gov (United States)

    Wang, Helin; Yang, Aijun

    2016-09-01

    With the As2Se3 photonic crystal fiber (PCF), the effect of pump power and wavelength on modulation instability (MI) gain is studied in detail. Due to high Raman scattering effect and high nonlinearity of As2Se3 PCF, ultra-broadband MI gain is obtained when appropriate pump power and wavelength is chosen, and the optimal MI gain bandwidth reaches 2812 nm. More importantly, competing between Raman scattering and four-wave mixing results in a single gain peak observed in the anti-Stokes region of As2Se3 PCF when pump power is higher than about 3000 W, while there is no gain spectrum in the fiber Stokes region. The phenomenon is found for the first time, and the obtained single gain peak mainly results from Raman scattering effect.

  19. Performance analysis of adaptive turbo coded modulation with time delay

    Institute of Scientific and Technical Information of China (English)

    伍守豪; 宋文涛; 罗汉文

    2004-01-01

    The method of data fitting is applied to obtain the BER expression for turbo coded modulation, and a fitting mathematical model is proposed, which resolves the problem that there is no exact BER expression for turbo coded modulation in performance analysis. With the time delay consideration, the performance of BER of adaptive turbo coded modulation is analyzed and simulated. The results show that adaptive turbo coded modulation is very sensitive to time delay. In order to meet the target BER requirement, the total time delay should be less than 0. 001/fD.

  20. Low-power, enhanced-gain adaptive-biasing-based Operational Transconductance Amplifiers

    DEFF Research Database (Denmark)

    Moradi, Farshad

    A symmetrical PMOS OTA (Operational Transconductance Amplifier) is used to build an advanced rail-to-rail amplifier with improved DC-gain and reduced power consumption. By using the adaptive biasing circuit for two differential inputs, a low stand-by current can be achieved, reducing power consum...

  1. On high-speed cross-gain modulation without pattern effects in quantum dot semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Uskov, A.V.; Mørk, Jesper; Tromborg, Bjarne;

    2003-01-01

    In the regime with maximum linear gain in a quantum dot (QD) semiconductor optical amplifier (SOA), instantaneous gain modulation by change of the photon density is possible due to spectral hole burning effects. This, in turn, leads to the opportunity of ultrafast cross-gain modulation (XGM...

  2. On the Performance of Adaptive Modulation in Cognitive Radio Networks

    OpenAIRE

    Foukalas, F.; Karetsos, G. T.

    2013-01-01

    We study the performance of cognitive radio networks (CRNs) when incorporating adaptive modulation at the physical layer. Three types of CRNs are considered, namely opportunistic spectrum access (OSA), spectrum sharing (SS) and sensing-based SS. We obtain closed-form expressions for the average spectral efficiency achieved at the secondary network and the optimal power allocation for both continuous and discrete rate types of adaptive modulation assuming perfect channel state information. The...

  3. Adaptive Robust Actuator Fault Accommodation for a Class of Uncertain Nonlinear Systems with Unknown Control Gains

    Directory of Open Access Journals (Sweden)

    Yuefei Wu

    2014-01-01

    Full Text Available An adaptive robust fault tolerant control approach is proposed for a class of uncertain nonlinear systems with unknown signs of high-frequency gain and unmeasured states. In the recursive design, neural networks are employed to approximate the unknown nonlinear functions, K-filters are designed to estimate the unmeasured states, and a dynamical signal and Nussbaum gain functions are introduced to handle the unknown sign of the virtual control direction. By incorporating the switching function σ algorithm, the adaptive backstepping scheme developed in this paper does not require the real value of the actuator failure. It is mathematically proved that the proposed adaptive robust fault tolerant control approach can guarantee that all the signals of the closed-loop system are bounded, and the output converges to a small neighborhood of the origin. The effectiveness of the proposed approach is illustrated by the simulation examples.

  4. Adaptive Fuzzy Robust Control for a Class of Nonlinear Systems via Small Gain Theorem

    Directory of Open Access Journals (Sweden)

    Xingjian Wang

    2013-01-01

    Full Text Available Practical nonlinear systems can usually be represented by partly linearizable models with unknown nonlinearities and external disturbances. Based on this consideration, we propose a novel adaptive fuzzy robust control (AFRC algorithm for such systems. The AFRC effectively combines techniques of adaptive control and fuzzy control, and it improves the performance by retaining the advantages of both methods. The linearizable part will be linearly parameterized with unknown but constant parameters, and the discontinuous-projection-based adaptive control law is used to compensate these parts. The Takagi-Sugeno fuzzy logic systems are used to approximate unknown nonlinearities. Robust control law ensures the robustness of closed-loop control system. A systematic design procedure of the AFRC algorithm by combining the backstepping technique and small-gain approach is presented. Then the closed-loop stability is studied by using small gain theorem, and the result indicates that the closed-loop system is semiglobally uniformly ultimately bounded.

  5. Adaptive Modulation for a Downlink Multicast Channel in OFDMA Systems

    DEFF Research Database (Denmark)

    Wang, Haibo; Schwefel, Hans-Peter; Toftegaard, Thomas Skjødeberg

    2007-01-01

    In this paper we focus on adaptive modulation strategies for multicast service in orthogonal frequency division multiple access systems. A reward function has been defined as the optimization target, which includes both the average user throughput and bit error rate. We also developed an adaptive...

  6. A Novel Broadband MIMO/OFDM System Using Adaptive Modulation and Adaptive Diversity

    Institute of Scientific and Technical Information of China (English)

    PANYahan; KhaledBenLetaief; CAOZhigang; QIUYonghong

    2005-01-01

    OFDM (Orthogonal frequency division multiplexing) has been widely regarded as an effective modulation technique for mitigating the effects of ISI in a frequency selective fading channel and for providing reliable high-data transmission over wireless links. Adaptive modulation combined with adaptive transmit and receive diversity can achieve further increases in system's capacity and bandwidth efficiency, as well as in QoS improvement in conventional OFDM systems. In this paper, we propose a novel broadband MIMO/OFDM system using adaptive modulation and adaptive transmit and receive diversity. By applying an EVD on each sub-carrier channel matrix, joint optimal transmit and receive antenna weights as well as maximal SNR on each sub-carrier are obtained. Then, by employing adaptive modulation on each sub-carrier, the maximal SNR on each sub-carrier obtained by adaptive transmit and receive diversity is further maximized through adaptive bit assignment and power assignment on each sub-carrier under the constraint of power and overall bit rate. Simulation results show that the proposed system can achieve better performance than an adaptive antenna array based OFDM system without adaptive modulation over multipath fading channels.

  7. Tuning of gravity-dependent and gravity-independent vertical angular VOR gain changes by frequency of adaptation.

    Science.gov (United States)

    Yakushin, Sergei B

    2012-06-01

    The gain of the vertical angular vestibulo-ocular reflex (aVOR) was adaptively increased and decreased in a side-down head orientation for 4 h in two cynomolgus monkeys. Adaptation was performed at 0.25, 1, 2, or 4 Hz. The gravity-dependent and -independent gain changes were determined over a range of head orientations from left-side-down to right-side-down at frequencies from 0.25 to 10 Hz, before and after adaptation. Gain changes vs. frequency data were fit with a Gaussian to determine the frequency at which the peak gain change occurred, as well as the tuning width. The frequency at which the peak gravity-dependent gain change occurred was approximately equal to the frequency of adaptation, and the width increased monotonically with increases in the frequency of adaptation. The gravity-independent component was tuned to the adaptive frequency of 0.25 Hz but was uniformly distributed over all frequencies when the adaptation frequency was 1-4 Hz. The amplitude of the gravity-independent gain changes was larger after the aVOR gain decrease than after the gain increase across all tested frequencies. For the aVOR gain decrease, the phase lagged about 4° for frequencies below the adaptation frequency and led for frequencies above the adaptation frequency. For gain increases, the phase relationship as a function of frequency was inverted. This study demonstrates that the previously described dependence of aVOR gain adaptation on frequency is a property of the gravity-dependent component of the aVOR only. The gravity-independent component of the aVOR had a substantial tuning curve only at an adaptation frequency of 0.25 Hz.

  8. Sliding mode control of wind-induced vibrations using fuzzy sliding surface and gain adaptation

    Science.gov (United States)

    Thenozhi, Suresh; Yu, Wen

    2016-04-01

    Although fuzzy/adaptive sliding mode control can reduce the chattering problem in structural vibration control applications, they require the equivalent control and the upper bounds of the system uncertainties. In this paper, we used fuzzy logic to approximate the standard sliding surface and designed a dead-zone adaptive law for tuning the switching gain of the sliding mode control. The stability of the proposed controller is established using Lyapunov stability theory. A six-storey building prototype equipped with an active mass damper has been used to demonstrate the effectiveness of the proposed controller towards the wind-induced vibrations.

  9. Dual Adaptive Turbo Coded Modulation for Integrated Multimedia Service Transmission

    Institute of Scientific and Technical Information of China (English)

    左健存; 宋文涛; 罗汉文; 徐友云

    2004-01-01

    This paper proposes a cross-layer dual adaptive coded modulation architecture using turbo codes for mobile multimedia communication, which adapts to both the varying channel characteristics and the QoS of various multimedia services simultaneously to increase the average system throughput substantially. A pragmatic channeladaptive turbo coded modulation scheme, which comes within 2.5 Db of the Shannon limit, is optimally designed,and then a QoS-adaptive scheme is superimposed to build the dual adaptive architecture. Simulation results show that the novel dual adaption reduces the gap from the fading channel capacity to 2 Db when assuming different services occur in equal probability and the service duration follows exponential distribution.

  10. Adaptive high gain observer based output feedback predictive controller for induction motor

    OpenAIRE

    Hadj Saïd, S.; M'Sahli, F.; Mimouni, F; Farza, Mondher

    2013-01-01

    An accurate estimation of both rotor and stator resistances is usually required to achieve high performance control in induction machine drive systems. In our study, an output feedback predictive controller which is adaptive with respect to these parameters uncertainties is proposed. Such design attempts to a fully decoupling in speed and flux magnitude when conjoint estimation of the state and the critical parameters is performed. Precisely, two-stage of high gain observer are used to provid...

  11. Output feedback adaptive control of multivariable nonlinear systems using Nussbaum gain method

    Institute of Scientific and Technical Information of China (English)

    Zhou Ying; Wu Yuqiang

    2006-01-01

    A new output feedback adaptive control scheme for multi-input and multi-output nonlinear systems with parametric uncertainty is presented based on the Nussbaum gain method and the backstepping approach. The high frequency gain matrix of the linear part of the system is not necessarily positive definite, but can be transformed into a lower or upper triangular matrix whose signs of diagonal elements are unknown. The new required condition for the high frequency gain matrix can be easily checked for certain plants so that the proposed method is widely applicable. The global stability of the closed loop systems is guaranteed through this control scheme, at the same time the tracking error converges to zero.

  12. Adaptive fuzzy dynamic surface control for the chaotic permanent magnet synchronous motor using Nussbaum gain

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Shaohua [School of Automation, Chongqing University, Chongqing 400044, China and College of Mechanical Engineering, Hunan University of Arts and Science, Hunan 415000 (China)

    2014-09-01

    This paper is concerned with the problem of adaptive fuzzy dynamic surface control (DSC) for the permanent magnet synchronous motor (PMSM) system with chaotic behavior, disturbance and unknown control gain and parameters. Nussbaum gain is adopted to cope with the situation that the control gain is unknown. And the unknown items can be estimated by fuzzy logic system. The proposed controller guarantees that all the signals in the closed-loop system are bounded and the system output eventually converges to a small neighborhood of the desired reference signal. Finally, the numerical simulations indicate that the proposed scheme can suppress the chaos of PMSM and show the effectiveness and robustness of the proposed method.

  13. Real-time digital phase and gain adaptation method using feedback and arrangement using such a method

    NARCIS (Netherlands)

    Kokkeler, André

    2004-01-01

    Arrangement for real-time phase and gain adaptation as a function of frequency and gain adaptation as a function of amplitude of an input signal in relation to an output signal, the input signal having a first absolute phase and first power as a function of frequency, the output signal having a seco

  14. L∞-gain adaptive fuzzy fault accommodation control design for nonlinear time-delay systems.

    Science.gov (United States)

    Wu, Huai-Ning; Qiang, Xiao-Hong; Guo, Lei

    2011-06-01

    In this paper, an adaptive fuzzy fault accommodation (FA) control design with a guaranteed L(∞)-gain performance is developed for a class of nonlinear time-delay systems with persistent bounded disturbances. Using the Lyapunov technique and the Razumikhin-type lemma, the existence condition of the L(∞) -gain adaptive fuzzy FA controllers is provided in terms of linear matrix inequalities (LMIs). In the proposed FA scheme, a fuzzy logic system is employed to approximate the unknown term in the derivative of the Lyapunov function due to the unknown fault function; a continuous-state feedback control strategy is adopted for the control design to avoid the undesirable chattering phenomenon. The resulting FA controllers can ensure that every response of the closed-loop system is uniformly ultimately bounded with a guaranteed L(∞)-gain performance in the presence of a fault. Moreover, by the existing LMI optimization technique, a suboptimal controller is obtained in the sense of minimizing an upper bound of the L(∞)-gain. Finally, the achieved simulation results on the FA control of a continuous stirred tank reactor (CSTR) show the effectiveness of the proposed design procedure.

  15. Adaptive gain control for spike-based map communication in a neuromorphic vision system.

    Science.gov (United States)

    Meng, Yicong; Shi, Bertram E

    2008-06-01

    To support large numbers of model neurons, neuromorphic vision systems are increasingly adopting a distributed architecture, where different arrays of neurons are located on different chips or processors. Spike-based protocols are used to communicate activity between processors. The spike activity in the arrays depends on the input statistics as well as internal parameters such as time constants and gains. In this paper, we investigate strategies for automatically adapting these parameters to maintain a constant firing rate in response to changes in the input statistics. We find that under the constraint of maintaining a fixed firing rate, a strategy based upon updating the gain alone performs as well as an optimal strategy where both the gain and the time constant are allowed to vary. We discuss how to choose the time constant and propose an adaptive gain control mechanism whose operation is robust to changes in the input statistics. Our experimental results on a mobile robotic platform validate the analysis and efficacy of the proposed strategy.

  16. High-Directional Wave Propagation in Periodic Gain/Loss Modulated Materials

    CERN Document Server

    Kumar, N; Herrero, R; Loiko, Yu; Staliunas, K

    2012-01-01

    Amplification/attenuation of light waves in artificial materials with a gain/loss modulation on the wavelength scale can be sensitive to the propagation direction. We give a numerical proof of the high anisotropy of the gain/loss in two dimensional periodic structures with square and rhombic lattice symmetry by solving the full set of Maxwell's equations using the finite difference time domain method. Anisotropy of amplification/attenuation leads to the narrowing of the angular spectrum of propagating radiation with wavevectors close to the edges of the first Brillouin Zone. The effect provides a novel and useful method to filter out high spatial harmonics from noisy beams.

  17. De Vries-Weber gain control and dark adaptation in human vision

    Science.gov (United States)

    Bouman, Maarten A.

    2002-02-01

    Thresholds for seeing light from a stimulus are determined by a mechanism that pairs subliminal excitations from both halves of a twin unit. Such excitations stem from a package of k>=1 receptor responses. A half-unit contains one red or one green cone and P rods. The receptor's ``Weber machine'' controls the receptor's gain. Each half of a twin unit contains a ``de Vries machine,'' which controls the half's k number. In the dark the receptor's dark noise events reset its Weber machine and the receptor's relation to its de Vries machine. A pairing product for light perception also represents a direction event. The local time signs of the two subliminal excitations are crucial for the polarity, size, and pace of the direction event. In relation to the time when and the area in which the stimulus is presented, these signs have average latency periods that depend on intensity and average locations that depend on movement. Polarity depends on which of the two subliminal excitations happens to arrive first at the twin's pairing facility. The intra- and inter-twin pairings in a persepton for the perceptions of light, edge and movement and the probability summation of the pairing products of the mutually independent three sets of twins of the retrinet improve intensity discrimination. Cross-pairings of intra-receptor pairings in red and green cones of a trion for yellow improve visual discrimination further. Discrimination of stimuli that exploit the model's entire summation mechanisms and pairing facilities represents ``what the perfect human eye sees best.'' For the model this threshold of modulation in quantum absorption is the ideal limit that is prescribed by statistical physics. The lateral and meta interaction in a twin unit enhance the contrast of an edge and of a temporal transient. The precision of the local time sign of a half's stimulation determines the spatiotemporal hyperfunctions for location and speed. The model's design for the perfect retinal mosaic

  18. Method and system for modulation of gain suppression in high average power laser systems

    Science.gov (United States)

    Bayramian, Andrew James

    2012-07-31

    A high average power laser system with modulated gain suppression includes an input aperture associated with a first laser beam extraction path and an output aperture associated with the first laser beam extraction path. The system also includes a pinhole creation laser having an optical output directed along a pinhole creation path and an absorbing material positioned along both the first laser beam extraction path and the pinhole creation path. The system further includes a mechanism operable to translate the absorbing material in a direction crossing the first laser beam extraction laser path and a controller operable to modulate the second laser beam.

  19. Influence of pump power and modulation instability gain spectrum on seeded supercontinuum and rogue wave generation

    DEFF Research Database (Denmark)

    Sørensen, Simon Toft; Larsen, Casper; Møller, Uffe;

    2012-01-01

    The noise properties of a supercontiuum can be significantly improved both in terms of coherence and intensity stability by modulating the input pulse with a seed. In this paper, we numerically investigate the influence of the seed wavelength, the pump power, and the modulation instability gain...... spectrum. Finally, we show that the coherent pulse breakup afforded by seeding is washed out by turbulent solitonic dynamics when the pump power is increased to the kilowatt level. Thus our results show that seeding cannot improve the noise performance of a high power supercontinuum source....

  20. Broadband microwave phase shifter based on high speed cross gain modulation in quantum dot semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Chen, Yaohui; Mørk, Jesper

    2009-01-01

    We present a scheme to achieve tunable ~180 degrees microwave phase shifts at frequencies exceeding 100 GHz based on high speed cross gain modulation in quantum dot semiconductor optical amplifiers.......We present a scheme to achieve tunable ~180 degrees microwave phase shifts at frequencies exceeding 100 GHz based on high speed cross gain modulation in quantum dot semiconductor optical amplifiers....

  1. Input and output gain modulation by the lateral interhemispheric network in early visual cortex.

    Science.gov (United States)

    Wunderle, Thomas; Eriksson, David; Peiker, Christiane; Schmidt, Kerstin E

    2015-05-20

    Neurons in the cerebral cortex are constantly integrating different types of inputs. Dependent on their origin, these inputs can be modulatory in many ways and, for example, change the neuron's responsiveness, sensitivity, or selectivity. To investigate the modulatory role of lateral input from the same level of cortical hierarchy, we recorded in the primary visual cortex of cats while controlling synaptic input from the corresponding contralateral hemisphere by reversible deactivation. Most neurons showed a pronounced decrease in their response to a visual stimulus of different contrasts and orientations. This indicates that the lateral network acts via an unspecific gain-setting mechanism, scaling the output of a neuron. However, the interhemispheric input also changed the contrast sensitivity of many neurons, thereby acting on the input. Such a contrast gain mechanism has important implications because it extends the role of the lateral network from pure response amplification to the modulation of a specific feature. Interestingly, for many neurons, we found a mixture of input and output gain modulation. Based on these findings and the known physiology of callosal connections in the visual system, we developed a simple model of lateral interhemispheric interactions. We conclude that the lateral network can act directly on its target, leading to a sensitivity change of a specific feature, while at the same time it also can act indirectly, leading to an unspecific gain setting. The relative contribution of these direct and indirect network effects determines the outcome for a particular neuron.

  2. Multiplicative gain modulation arising from inhibitory synaptic plasticity in the cerebellar nuclei

    Directory of Open Access Journals (Sweden)

    Dimitris Bampasakis

    2014-03-01

    Full Text Available Neurons use the rate of action potentials to encode sensory variables. This makes the output rate as a function of input, also known as input-output (I–O relationship, a core computational function in neuronal processing. The introduction, or increase, of a modulatory input, can transform this function in multiple ways: additive transformations result in a shift, and multiplicative transformations in a change of slope of the I–O relationship. This slope change is known as gain modulation, and it can implement important forms of neural computation such as coordinate transformations. Gain modulation can be found in a wide range of brain systems, including the cerebellum, where it can be enabled by synaptic plasticity at both excitatory and inhibitory synapses. We use a realistic, conductance based, multi-compartmental model of a cerebellar nucleus (CN neuron, to investigate the determinants of gain modulation mediated by synaptic plasticity. In particular, we are interested in the effect of short term depression (STD at the inhibitory synapse from Purkinje cells (PCs to CN neurons. Considering the inhibitory PC input as the driving input, we compare the I–O relationship of the CN neuron in the presence and absence of STD for 20 Hz of excitatory synaptic input from mossy fibers (MFs, and find that STD introduces a gain change, changing the slope of the I–O function. We then proceed to compare the transformation performed by the increase of the modulatory input from 20 to 50 Hz, in the presence and absence of STD. We find that the presence of STD in the inhibitory synapse introduces a multiplicative component in the transformation performed by the excitatory input, an effect that persists for different levels of STD, and various combinations of regularity and synchronicity in the input.

  3. Inhibition Shapes Response Selectivity in the Inferior Colliculus by Gain Modulation

    Directory of Open Access Journals (Sweden)

    Joshua X Gittelman

    2012-09-01

    Full Text Available Pharmacological block of inhibition is often used to determine if inhibition contributes to spike selectivity, in which a preferred stimulus evokes more spikes than a null stimulus. When inhibitory block reduces spike selectivity, a common interpretation is that differences between the preferred- and null-evoked inhibitions created the selectivity from less-selective excitatory inputs. In models based on empirical properties of cells from the inferior colliculus of awake bats, we show that inhibitory differences are not required. Instead, inhibition can enhance spike selectivity by changing the gain, the ratio of output spikes to input current. Within the model, we made preferred stimuli that evoked more spikes than null stimuli using five distinct synaptic mechanisms. In two cases, synaptic selectivity (the differences between the preferred and null inputs was entirely excitatory, and in two it was entirely inhibitory. In each case, blocking inhibition eliminated spike selectivity. Thus, observing spike rates following inhibitory block did not distinguish among the cases where synaptic selectivity was entirely excitatory or inhibitory. We then did the same modeling experiment using empirical synaptic conductances derived from responses to preferred and null sounds. In most cases, inhibition in the model enhanced spike selectivity mainly by gain modulation and firing rate reduction. Sometimes, inhibition reduced the null gain to zero, eliminating null-evoked spikes. In some cases, inhibition increased the preferred gain more than the null gain, enhancing the difference between the preferred- and null-evoked spikes. Finally, inhibition kept firing rates low. When selectivity is quantified by the selectivity index (SI, the ratio of the difference to the sum of the spikes evoked by the preferred and null stimuli, inhibitory block reduced the SI by increasing overall firing rates. These results are consistent with inhibition shaping spike

  4. Omnidirectional mirror based on Bragg stacks with a periodic gain-loss modulation

    Energy Technology Data Exchange (ETDEWEB)

    Manzanares-Martinez, Jesus; Ham-Rodriguez, Carlos Ivan [Departamento de Investigacion en Fisica, Universidad de Sonora, Apartado Postal 5-088, Hermosillo, Sonora 83000 (Mexico); Moctezuma-Enriquez, Damian, E-mail: foxonicos@gmail.com [Centro de Investigacion en Materiales Avanzados (CIMAV), Miguel de Cervantes 120, Chihuahua 31109 (Mexico); Manzanares-Martinez, Betsabe [Departamento de Fisica, Universidad de Sonora, Blvd. Luis Encinas y Rosales, Hermosillo, Sonora 83000 (Mexico)

    2014-01-15

    In this work we demonstrate that a Bragg Stack with a periodic gain-loss modulation can function as an Omnidirectional Mirror (OM) with complete reflection at any angle of incidence irrespective of the light polarization. The Bragg Stack is composed by the periodic variation of two layers with the same value of the real part of the refractive index (n{sub r}) and a periodic modulation in the imaginary part (n{sub i}). The origin of the band gaps is due to the interference of complex waves with propagating and evanescent fields in each layer. It is found that the band gaps are wider as the contrast n{sub i}/n{sub r} increases. We have found the ambient conditions to obtain an OM considering an auxiliary medium n{sup ′} external to the Bragg Stack.

  5. Spectral Phase Modulation and chirped pulse amplification in High Gain Harmonic Generation

    CERN Document Server

    Wu, Zilu; Krinsky, Sam; Loos, Henrik; Murphy, James; Shaftan, Timur; Sheehy, Brian; Shen, Yuzhen; Wang, Xijie; Yu Li Hua

    2004-01-01

    High Gain Harmonic Generation (HGHG), because it produces longitudinally coherent pulses derived from a coherent seed, presents remarkable possibilities for manipulating FEL pulses. If spectral phase modulation imposed on the seed modulates the spectral phase of the HGHG in a deterministic fashion, then chirped pulse amplification, pulse shaping, and coherent control experiments at short wavelengths become possible. In addition, the details of the transfer function will likely depend on electron beam and radiator dynamics and so prove to be a useful tool for studying these. Using the DUVFEL at the National Synchrotron Light Source at Brookhaven National Laboratory, we present spectral phase analyses of both coherent HGHG and incoherent SASE ultraviolet FEL radiation, applying Spectral Interferometry for Direct Electric Field Reconstruction (SPIDER), and assess the potential for employing compression and shaping techniques.

  6. High speed gain coupled DFB laser diode integrated with MQW electroabsorption modulator

    International Nuclear Information System (INIS)

    We have demonstrated stable modulation characteristics of the gain coupled distributed feedback(GC-DFB) laser diode integrated with butt-coupled InGaAsP/InGaAsP strain compensated MQW(multiple-Quantum-well) modulator for high speed optical transmission. For this purpose, we have adopted the InGaAsP/InGaAsP strain compensated MQW structure for the EA modulator and n-doped InGaAs absorptive grating for DFB laser. The typical threshold current and slope efficiency were about 15 mA and 0.1 mW/mA, respectively. The extinction ratio of fabricated integrated device was about 15 dB at -2 V, and the small signal bandwidth was shown to be around 17GHz. We also found that the α parameter becomes negative at below a -0.6 V bias voltage. We transmitted 10 Gbps NRZ electrical signal over 90 km of standard single mode optical fiber (SMF). A clearly opened eye diagram was observed in the modulated output

  7. High speed gain coupled DFB laser diode integrated with MQW electroabsorption modulator

    CERN Document Server

    Kim, M G; Park, S S; Oh, D K; Lee, H T; Kim, H M; Pyun, K E

    1998-01-01

    We have demonstrated stable modulation characteristics of the gain coupled distributed feedback(GC-DFB) laser diode integrated with butt-coupled InGaAsP/InGaAsP strain compensated MQW(multiple-Quantum-well) modulator for high speed optical transmission. For this purpose, we have adopted the InGaAsP/InGaAsP strain compensated MQW structure for the EA modulator and n-doped InGaAs absorptive grating for DFB laser. The typical threshold current and slope efficiency were about 15 mA and 0.1 mW/mA, respectively. The extinction ratio of fabricated integrated device was about 15 dB at -2 V, and the small signal bandwidth was shown to be around 17GHz. We also found that the alpha parameter becomes negative at below a -0.6 V bias voltage. We transmitted 10 Gbps NRZ electrical signal over 90 km of standard single mode optical fiber (SMF). A clearly opened eye diagram was observed in the modulated output.

  8. The research on thermal adaptability reinforcement technology for photovoltaic modules

    Science.gov (United States)

    Su, Nana; Zhou, Guozhong

    2015-10-01

    Nowadays, Photovoltaic module contains more high-performance components in smaller space. It is also demanded to work in severe temperature condition for special use, such as aerospace. As temperature rises, the failure rate will increase exponentially which makes reliability significantly reduce. In order to improve thermal adaptability of photovoltaic module, this paper makes a research on reinforcement technologies. Thermoelectric cooler is widely used in aerospace which has harsh working environment. So, theoretical formulas for computing refrigerating efficiency, refrigerating capacity and temperature difference are described in detail. The optimum operating current of three classical working condition is obtained which can be used to guide the design of driven circuit. Taken some equipment enclosure for example, we use thermoelectric cooler to reinforce its thermal adaptability. By building physical model and thermal model with the aid of physical dimension and constraint condition, the model is simulated by Flotherm. The temperature field cloud is shown to verify the effectiveness of reinforcement.

  9. Tunable coherence-free microwave photonic bandpass filter based on double cross gain modulation technique.

    Science.gov (United States)

    Chan, Erwin H W

    2012-10-01

    A tunable, coherence-free, high-resolution microwave photonic bandpass filter, which is compatible to be inserted in a conventional fiber optic link, is presented. It is based on using two cross gain modulation based wavelength converters in a recursive loop. The double cross gain modulation technique solves the semiconductor optical amplifier facet reflection problem in the conventional recursive structure; hence the new microwave photonic signal processor has no coherent interference and no phase-induced intensity noise. It allows arbitrary narrow-linewidth telecommunication-type lasers to be used while enabling stable filter operation to be realized. The filter passband frequency can be tuned by using a wavelength tunable laser and a wavelength dependent time delay component. Experimental results demonstrate robust high-resolution bandpass filter operation with narrow-linewidth sources, no phase-induced intensity noise and a high signal-to-noise ratio performance. Tunable coherence-free operation of the high-resolution bandpass filter is also demonstrated. PMID:23188262

  10. On Practical Issues of Adaptive Modulation in OFDM Systems

    Institute of Scientific and Technical Information of China (English)

    WU Jun-li; YIN Chang-chuan; YUE Guang-xin

    2005-01-01

    The performance of Orthogonal Frequency Division Multiplexing(OFDM)systems with Adaptive Modulation(AM)is studied in this paper.Some factors in the system including frequency group,time interval Channel State Information(CSI)estimation error and channel delay are analyzed.The results of simulation prove the efficiency of AM-OFDM,and indicate CSI estimation error affects the performance of AM-OFDM seriously.

  11. Joint adaptive modulation and diversity combining with feedback error compensation

    KAUST Repository

    Choi, Seyeong

    2009-11-01

    This letter investigates the effect of feedback error on the performance of the joint adaptive modulation and diversity combining (AMDC) scheme which was previously studied with an assumption of error-free feedback channels. We also propose to utilize adaptive diversity to compensate for the performance degradation due to feedback error. We accurately quantify the performance of the joint AMDC scheme in the presence of feedback error, in terms of the average number of combined paths, the average spectral efficiency, and the average bit error rate. Selected numerical examples are presented and discussed to illustrate the effectiveness of the proposed feedback error compensation strategy with adaptive combining. It is observed that the proposed compensation strategy can offer considerable error performance improvement with little loss in processing power and spectral efficiency in comparison with the no compensation case. Copyright © 2009 IEEE.

  12. SIRT1 Gain of Function Does Not Mimic or Enhance the Adaptations to Intermittent Fasting

    Directory of Open Access Journals (Sweden)

    Marie Boutant

    2016-03-01

    Full Text Available Caloric restriction (CR has been shown to prevent the onset of insulin resistance and to delay age-related physiological decline in mammalian organisms. SIRT1, a NAD+-dependent deacetylase enzyme, has been suggested to mediate the adaptive responses to CR, leading to the speculation that SIRT1 activation could be therapeutically used as a CR-mimetic strategy. Here, we used a mouse model of moderate SIRT1 overexpression to test whether SIRT1 gain of function could mimic or boost the metabolic benefits induced by every-other-day feeding (EODF. Our results indicate that SIRT1 transgenesis does not affect the ability of EODF to decrease adiposity and improve insulin sensitivity. Transcriptomic analyses revealed that SIRT1 transgenesis and EODF promote very distinct adaptations in individual tissues, some of which can be even be metabolically opposite, as in brown adipose tissue. Therefore, whereas SIRT1 overexpression and CR both improve glucose metabolism and insulin sensitivity, the etiologies of these benefits are largely different.

  13. SIRT1 Gain of Function Does Not Mimic or Enhance the Adaptations to Intermittent Fasting.

    Science.gov (United States)

    Boutant, Marie; Kulkarni, Sameer S; Joffraud, Magali; Raymond, Frédéric; Métairon, Sylviane; Descombes, Patrick; Cantó, Carles

    2016-03-01

    Caloric restriction (CR) has been shown to prevent the onset of insulin resistance and to delay age-related physiological decline in mammalian organisms. SIRT1, a NAD(+)-dependent deacetylase enzyme, has been suggested to mediate the adaptive responses to CR, leading to the speculation that SIRT1 activation could be therapeutically used as a CR-mimetic strategy. Here, we used a mouse model of moderate SIRT1 overexpression to test whether SIRT1 gain of function could mimic or boost the metabolic benefits induced by every-other-day feeding (EODF). Our results indicate that SIRT1 transgenesis does not affect the ability of EODF to decrease adiposity and improve insulin sensitivity. Transcriptomic analyses revealed that SIRT1 transgenesis and EODF promote very distinct adaptations in individual tissues, some of which can be even be metabolically opposite, as in brown adipose tissue. Therefore, whereas SIRT1 overexpression and CR both improve glucose metabolism and insulin sensitivity, the etiologies of these benefits are largely different. PMID:26923584

  14. Capacity achieving nonbinary LDPC coded non-uniform shaping modulation for adaptive optical communications.

    Science.gov (United States)

    Lin, Changyu; Zou, Ding; Liu, Tao; Djordjevic, Ivan B

    2016-08-01

    A mutual information inspired nonbinary coded modulation design with non-uniform shaping is proposed. Instead of traditional power of two signal constellation sizes, we design 5-QAM, 7-QAM and 9-QAM constellations, which can be used in adaptive optical networks. The non-uniform shaping and LDPC code rate are jointly considered in the design, which results in a better performance scheme for the same SNR values. The matched nonbinary (NB) LDPC code is used for this scheme, which further improves the coding gain and the overall performance. We analyze both coding performance and system SNR performance. We show that the proposed NB LDPC-coded 9-QAM has more than 2dB gain in symbol SNR compared to traditional LDPC-coded star-8-QAM. On the other hand, the proposed NB LDPC-coded 5-QAM and 7-QAM have even better performance than LDPC-coded QPSK. PMID:27505775

  15. Two-user opportunistic scheduling using hierarchical modulations in wireless networks with heterogenous average link gains

    KAUST Repository

    Hossain, Md Jahangir

    2010-03-01

    Our contribution, in this paper, is two-fold. First, we analyze the performance of a hierarchical modulation-assisted two-best user opportunistic scheduling (TBS) scheme, which was proposed by the authors, in a fading environment where different users have different average link gains. Specifically, we present a new expression for the spectral efficiency (SE) of the users and using this expression, we compare the degrees of fairness (DOF) of the TBS scheme with that of classical single user opportunistic scheduling schemes, namely, absolute carrier-to-noise ratio (CNR) based single-best user scheduling (SBS) and normalized CNR based proportional fair scheduling (PFS) schemes. The second contribution is that we propose a new hybrid two-user opportunistic scheduling (HTS) scheme based on our earlier proposed TBS scheme. This HTS scheme selects the first user based on the largest absolute CNR value among all the users while the second user is selected based on the ratios of the absolute CNRs to the corresponding average CNRs of the remaining users. The total transmission rate i.e., the constellation size is selected according to the absolute CNR of the first best user. The total transmission rate is then allocated among these selected users by joint consideration of their absolute CNRs and allocated number of information bit(s) are transmitted to them using hierarchical modulations. Numerical results are presented for a fading environment where different users experience independent but non-identical (i.n.d.) channel fading. These selected numerical results show that the proposed HTS scheme can considerably increase the system\\'s fairness without any degradation of the link spectral efficiency (LSE) i.e., the multiuser diversity gain compared to the classical SBS scheme. These results also show that the proposed HTS scheme has a lower fairness in comparison to the PFS scheme which suffers from a considerable degradation in LSE. © 2010 IEEE.

  16. Power adaptation for joint switched diversity and adaptive modulation schemes in spectrum sharing systems

    KAUST Repository

    Bouida, Zied

    2012-09-01

    Under the scenario of an underlay cognitive radio network, we propose in this paper an adaptive scheme using transmit power adaptation, switched transmit diversity, and adaptive modulation in order to improve the performance of existing switching efficient schemes (SES) and bandwidth efficient schemes (BES). Taking advantage of the channel reciprocity principle, we assume that the channel state information (CSI) of the interference link is available to the secondary transmitter. This information is then used by the secondary transmitter to adapt its transmit power, modulation constellation size, and used transmit branch. The goal of this joint adaptation is to minimize the average number of switched branches and the average system delay given the fading channel conditions, the required error rate performance, and a peak interference constraint to the primary receiver. We analyze the proposed scheme in terms of the average number of branch switching, average delay, and we provide a closed-form expression of the average bit error rate (BER). We demonstrate through numerical examples that the proposed scheme provides a compromise between the SES and the BES schemes. © 2012 IEEE.

  17. Joint Adaptive Modulation-Coding and Cooperative ARQ for Wireless Relay Networks

    CERN Document Server

    Mardani, Morteza; Lahouti, Farshad; Eliasi, Behrouz

    2008-01-01

    This paper presents a cross-layer approach to jointly design adaptive modulation and coding (AMC) at the physical layer and cooperative truncated automatic repeat request (ARQ) protocol at the data link layer. We first derive an exact closed form expression for the spectral efficiency of the proposed joint AMC-cooperative ARQ scheme. Aiming at maximizing this system performance measure, we then optimize an AMC scheme which directly satisfies a prescribed packet loss rate constraint at the data-link layer. The results indicate that utilizing cooperative ARQ as a retransmission strategy, noticeably enhances the spectral efficiency compared with the system that employs AMC alone at the physical layer. Moreover, the proposed adaptive rate cooperative ARQ scheme outperforms the fixed rate counterpart when the transmission modes at the source and relay are chosen based on the channel statistics. This in turn quantifies the possible gain achieved by joint design of AMC and ARQ in wireless relay networks.

  18. PERFORMANCES OF ADAPTIVE MODULATION AND CODING IN SATELLITE MOBILE CHANNEL

    Institute of Scientific and Technical Information of China (English)

    Yu Fangyuan; Yang Mingchuan; Guo Qing

    2011-01-01

    Given that satellite mobile channel is a time-varying channel,Adaptive Modulation and Coding (AMC) was proposed to provide robust and spectrally efficient transmission over satellite mobile channel.Three different kinds of channel environment were considered in this paper:the urban area,the rural area,and the open space.Four combinations of modulation and coding were designed to meet reliable communication on time-varying channel,and spectral efficiency and system throughput of these three kinds of channel environment were simulated.Based on the simulation results,this paper analysed the results and compared the performances of AMC with non-AMC system in these three kinds of channel environment.At last,we come to the conclusions:a system with AMC can achieve higher spectral efficiency and better system throughput; and the spectral efficiency and system throughput of AMC system will be higher on better satellite mobile channel.

  19. Study of adaptive modulation and LDPC coding in multicarrier systems

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    An adaptive modulation (AM) algorithm is proposed and the application of the adapting algorithm together with low-density parity-check (LDPC) codes in multicarrier systems is investigated.The AM algorithm is based on minimizing the average bit error rate (BER) of systems,the combination of AM algorithm and LDPC codes with different code rates (half and three-fourths) are studied.The proposed AM algorithm with that of Fischer et al is compared.Simulation results show that the performance of the proposed AM algorithm is better than that of the Fischer's algorithm.The results also show that application of the proposed AM algorithm together with LDPC codes can greatly improve the performance of multicarrier systems.Results also show that the performance of the proposed algorithm is degraded with an increase in code rate when code length is the same.

  20. SOAR Adaptive Module (SAM): seeing improvement with a UV laser

    CERN Document Server

    Tokovinin, Andrei; Tighe, Roberto; Schurter, Patricio; Martinez, Manuel; Thomas, Sandrine; van der Bliek, Nicole

    2016-01-01

    The adaptive module of the 4.1-m SOAR telescope, SAM, corrects ground-layer turbulence using a UV laser guide star. It has been commissioned in 2013 and it is in regular science operation since 2014. SAM works with the CCD imager covering a 3' field or with the speckle camera. It operates routinely and stably, delivering resolution in the I band equal to the free-atmosphere seeing. This paper describes the SAM system as a whole, providing essential reference for its users and technical information of interest to instrumentalists. Operation of the instrument, its performance, and science projects done with SAM so far are reviewed.

  1. Seed Pubescence and Shape Modulate Adaptive Responses to Fire Cues.

    Science.gov (United States)

    Gómez-González, Susana; Ojeda, Fernando; Torres-Morales, Patricio; Palma, Jazmín E

    2016-01-01

    Post-fire recruitment by seeds is regarded as an adaptive response in fire-prone ecosystems. Nevertheless, little is known about which heritable seed traits are functional to the main signals of fire (heat and smoke), thus having the potential to evolve. Here, we explored whether three seed traits (pubescence, dormancy and shape) and fire regime modulate seed response to fire cues(heat and smoke). As a model study system, we used Helenium aromaticum (Asteraceae), a native annual forb from the Chilean matorral, where fires are anthropogenic. We related seed trait values with fitness responses (germination and survival) after exposure to heat-shock and smoke experimental treatments on seeds from 10 H. aromaticum wild populations. We performed a phenotypic selection experiment to examine the relationship of seed traits with post-treatment fitness within a population (adaptive hypothesis). We then explored whether fire frequency in natural habitats was associated with trait expression across populations, and with germination and survival responses to experimental fire-cues. We found that populations subjected to higher fire frequency had, in average, more rounded and pubescent seeds than populations from rarely burned areas. Populations with more rounded and pubescent seeds were more resistant to 80°C heat-shock and smoke treatments.There was correlated selection on seed traits: pubescent-rounded or glabrouscent-elongated seeds had the highest probability of germinating after heat-shock treatments. Seed pubescence and shape in H. aromaticum are heritable traits that modulate adaptive responses to fire. Our results provide new insights into the process of plant adaptation to fire and highlight the relevance of human-made fires as a strong evolutionary agent in the Anthropocene. PMID:27438267

  2. Speech Enhancement, Gain, and Noise Spectrum Adaptation Using Approximate Bayesian Estimation.

    Science.gov (United States)

    Hao, Jiucang; Attias, Hagai; Nagarajan, Srikantan; Lee, Te-Won; Sejnowski, Terrence J

    2009-01-01

    This paper presents a new approximate Bayesian estimator for enhancing a noisy speech signal. The speech model is assumed to be a Gaussian mixture model (GMM) in the log-spectral domain. This is in contrast to most current models in frequency domain. Exact signal estimation is a computationally intractable problem. We derive three approximations to enhance the efficiency of signal estimation. The Gaussian approximation transforms the log-spectral domain GMM into the frequency domain using minimal Kullback-Leiber (KL)-divergency criterion. The frequency domain Laplace method computes the maximum a posteriori (MAP) estimator for the spectral amplitude. Correspondingly, the log-spectral domain Laplace method computes the MAP estimator for the log-spectral amplitude. Further, the gain and noise spectrum adaptation are implemented using the expectation-maximization (EM) algorithm within the GMM under Gaussian approximation. The proposed algorithms are evaluated by applying them to enhance the speeches corrupted by the speech-shaped noise (SSN). The experimental results demonstrate that the proposed algorithms offer improved signal-to-noise ratio, lower word recognition error rate, and less spectral distortion. PMID:20428253

  3. Stable Short-Term Frequency Support Using Adaptive Gains for a DFIG-Based Wind Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jinsik; Jang, Gilsoo; Muljadi, Eduard; Blaabjerg, Frede; Chen, Zhe; Cheol Kang, Yong

    2016-09-01

    For the fixed-gain inertial control of wind power plants (WPPs), a large gain setting provides a large contribution to supporting system frequency control, but it may cause over-deceleration for a wind turbine generator that has a small amount of kinetic energy (KE). Further, if the wind speed decreases during inertial control, even a small gain may cause over-deceleration. This paper proposes a stable inertial control scheme using adaptive gains for a doubly fed induction generator (DFIG)-based WPP. The scheme aims to improve the frequency nadir (FN) while ensuring stable operation of all DFIGs, particularly when the wind speed decreases during inertial control. In this scheme, adaptive gains are set to be proportional to the KE stored in DFIGs, which is spatially and temporally dependent. To improve the FN, upon detecting an event, large gains are set to be proportional to the KE of DFIGs; to ensure stable operation, the gains decrease with the declining KE. The simulation results demonstrate that the scheme improves the FN while ensuring stable operation of all DFIGs in various wind and system conditions. Further, it prevents over-deceleration even when the wind speed decreases during inertial control.

  4. Image-based Position Estimation and Adaptive Modulation Coding in Vehicular Communication

    Directory of Open Access Journals (Sweden)

    Hao Yang

    2011-12-01

    Full Text Available Vehicle position estimation is a key technology for Inter-Vehicle Communications, while template matching can be used to get information of vehicular position. In the paper, a simplified template matching, namely area-based template match is considered. A vehicular communication system designed for wireless data application is proposed where a camera is fixed in a vehicle which is served as a base station. By means of comparison between the outline area of vehicular image and reference templates, the base station can obtain the position estimation of the vehicle. The reference templates can be pre-calculated from a group of field experiment data. Based on supervised learning, we develop an image-based vehicle position estimation method and evaluate its effect on an adaptive coding modulation scheme. The computer simulation results show that in the wireless fading channel with the OFDM physical model, compared with fixed modulation coding scheme, the studied adaptive modulation and coding (AMC scheme taking account of the position estimation can gain greater throughput.

  5. Scaling of gain bounds for switched adaptive control with large uncertainties

    OpenAIRE

    Buchstaller, Dominic; French, Mark

    2007-01-01

    A wide class of MMAC with a finite lp closed loop gain are shown to have an unboundedly increasing l_p closed loop gain for a simple set of plants under increasing parametric uncertainty. A modification is proposed which achieves a quadratic closed loop gain function which is independent of the size of the uncertainty set.

  6. Feedback Stabilization over Wireless Network Using Adaptive Coded Modulation

    Institute of Scientific and Technical Information of China (English)

    Li Yang; Xin-Ping Guan; Cheng-Nian Long; Xiao-Yuan Luo

    2008-01-01

    In this paper, we apply adaptive coded modulation (ACM) schemes to a wireless networked control system (WNCS)to improve the energy efficiency and increase the data rate over a fading channel. To capture the characteristics of varying rate,interference, and routing in wireless transmission channels, the concepts of equivalent delay (ED) and networked condition index (NCI)are introduced. Also, the analytic lower and upper bounds of EDs are obtained. Furthermore, we model the WNCS as a multicontroller switched system (MSS) under consideration of EDs and loss index in the wireless transmission. Sufficient stability condition of the closed-loop WNCS and corresponding dynamic state feedback controllers are derived in terms of linear matrix inequality (LMI).Numerical results show the validity and advantage of our proposed control strategies.

  7. Cascadability improvement of a Cross-gain modulation wavelength converter using a grating based oiptical add/drop multiplexer

    DEFF Research Database (Denmark)

    Xueyan, Zheng; Liu, Fenghai

    2000-01-01

    By adding a grating based optical add/drop multiplexer, the maximum cascaded number of a cross-gain modulation based wavelength converter is improved from two to six rounds in a loop experiment at 10 Gb/s due to the improved high frequency response of the converter....

  8. Functional modules of sigma factor regulons guarantee adaptability and evolvability

    Science.gov (United States)

    Binder, Sebastian C.; Eckweiler, Denitsa; Schulz, Sebastian; Bielecka, Agata; Nicolai, Tanja; Franke, Raimo; Häussler, Susanne; Meyer-Hermann, Michael

    2016-02-01

    The focus of modern molecular biology turns from assigning functions to individual genes towards understanding the expression and regulation of complex sets of molecules. Here, we provide evidence that alternative sigma factor regulons in the pathogen Pseudomonas aeruginosa largely represent insulated functional modules which provide a critical level of biological organization involved in general adaptation and survival processes. Analysis of the operational state of the sigma factor network revealed that transcription factors functionally couple the sigma factor regulons and significantly modulate the transcription levels in the face of challenging environments. The threshold quality of newly evolved transcription factors was reached faster and more robustly in in silico testing when the structural organization of sigma factor networks was taken into account. These results indicate that the modular structures of alternative sigma factor regulons provide P. aeruginosa with a robust framework to function adequately in its environment and at the same time facilitate evolutionary change. Our data support the view that widespread modularity guarantees robustness of biological networks and is a key driver of evolvability.

  9. Performance analysis of adaptive modulation for cognitive radios with opportunistic access

    KAUST Repository

    Chen, Yunfei

    2011-06-01

    The performance of adaptive modulation for cognitive radio with opportunistic access is analyzed by considering the effects of spectrum sensing and primary user traffic for Nakagami-m fading channels. Both the adaptive continuous rate scheme and the adaptive discrete rate scheme are considered. Numerical results show that spectrum sensing and primary user traffic cause considerable degradation to the bit error rate performance of adaptive modulation in a cognitive radio system with opportunistic access to the licensed channel. They also show that primary user traffic does not affect the link spectral efficiency performance of adaptive modulation, while the spectrum sensing degrades the link spectral efficiency performance. © 2011 IEEE.

  10. Dosimetrically Triggered Adaptive Intensity Modulated Radiation Therapy for Cervical Cancer

    International Nuclear Information System (INIS)

    Purpose: The widespread use of intensity modulated radiation therapy (IMRT) for cervical cancer has been limited by internal target and normal tissue motion. Such motion increases the risk of underdosing the target, especially as planning margins are reduced in an effort to reduce toxicity. This study explored 2 adaptive strategies to mitigate this risk and proposes a new, automated method that minimizes replanning workload. Methods and Materials: Thirty patients with cervical cancer participated in a prospective clinical study and underwent pretreatment and weekly magnetic resonance (MR) scans over a 5-week course of daily external beam radiation therapy. Target volumes and organs at risk (OARs) were contoured on each of the scans. Deformable image registration was used to model the accumulated dose (the real dose delivered to the target and OARs) for 2 adaptive replanning scenarios that assumed a very small PTV margin of only 3 mm to account for setup and internal interfractional motion: (1) a preprogrammed, anatomy-driven midtreatment replan (A-IMRT); and (2) a dosimetry-triggered replan driven by target dose accumulation over time (D-IMRT). Results: Across all 30 patients, clinically relevant target dose thresholds failed for 8 patients (27%) if 3-mm margins were used without replanning. A-IMRT failed in only 3 patients and also yielded an additional small reduction in OAR doses at the cost of 30 replans. D-IMRT assured adequate target coverage in all patients, with only 23 replans in 16 patients. Conclusions: A novel, dosimetry-triggered adaptive IMRT strategy for patients with cervical cancer can minimize the risk of target underdosing in the setting of very small margins and substantial interfractional motion while minimizing programmatic workload and cost

  11. The Effect of Adaptive Gain and Adaptive Momentum in Improving Training Time of Gradient Descent Back Propagation Algorithm on Classification Problems

    Directory of Open Access Journals (Sweden)

    Norhamreeza Abdul Hamid

    2011-01-01

    Full Text Available The back propagation algorithm has been successfully applied to wide range of practical problems. Since this algorithm uses a gradient descent method, it has some limitations which are slow learning convergence velocity and easy convergence to local minima. The convergence behaviour of the back propagation algorithm depends on the choice of initial weights and biases, network topology, learning rate, momentum, activation function and value for the gain in the activation function. Previous researchers demonstrated that in ‘feed forward’ algorithm, the slope of the activation function is directly influenced by a parameter referred to as ‘gain’. This research proposed an algorithm for improving the performance of the current working back propagation algorithm which is Gradien Descent Method with Adaptive Gain by changing the momentum coefficient adaptively for each node. The influence of the adaptive momentum together with adaptive gain on the learning ability of a neural network is analysed. Multilayer feed forward neural networks have been assessed. Physical interpretation of the relationship between the momentum value, the learning rate and weight values is given. The efficiency of the proposed algorithm is compared with conventional Gradient Descent Method and current Gradient Descent Method with Adaptive Gain was verified by means of simulation on three benchmark problems. In learning the patterns, the simulations result demonstrate that the proposed algorithm converged faster on Wisconsin breast cancer with an improvement ratio of nearly 1.8, 6.6 on Mushroom problem and 36% better on  Soybean data sets. The results clearly show that the proposed algorithm significantly improves the learning speed of the current gradient descent back-propagatin algorithm.

  12. Performance analysis of two-way amplify and forward relaying with adaptive modulation

    KAUST Repository

    Hwang, Kyusung

    2009-09-01

    In this paper, we study two-way amplify-and-forward relaying in conjunction with adaptive modulation over a multiple relay network. In order to keep the diversity order equal to the number of relays and maintain a low complexity, we consider the best relay selection scheme in this work. Based on the proposed selection criterion for the best relay, we analyze the average spectral efficiency by its approximated upper bound. In addition, we extend the proposed scheme to the case where a direct path between source and destination exists. Our numerical examples show that the proposed system offers a considerable gain in the spectral efficiency while satisfying the error rates requirements. ©2009 IEEE.

  13. Configurable multiplier modules for an adaptive computing system

    Directory of Open Access Journals (Sweden)

    O. A. Pfänder

    2006-01-01

    Full Text Available The importance of reconfigurable hardware is increasing steadily. For example, the primary approach of using adaptive systems based on programmable gate arrays and configurable routing resources has gone mainstream and high-performance programmable logic devices are rivaling traditional application-specific hardwired integrated circuits. Also, the idea of moving from the 2-D domain into a 3-D design which stacks several active layers above each other is gaining momentum in research and industry, to cope with the demand for smaller devices with a higher scale of integration. However, optimized arithmetic blocks in course-grain reconfigurable arrays as well as field-programmable architectures still play an important role. In countless digital systems and signal processing applications, the multiplication is one of the critical challenges, where in many cases a trade-off between area usage and data throughput has to be made. But the a priori choice of word-length and number representation can also be replaced by a dynamic choice at run-time, in order to improve flexibility, area efficiency and the level of parallelism in computation. In this contribution, we look at an adaptive computing system called 3-D-SoftChip to point out what parameters are crucial to implement flexible multiplier blocks into optimized elements for accelerated processing. The 3-D-SoftChip architecture uses a novel approach to 3-dimensional integration based on flip-chip bonding with indium bumps. The modular construction, the introduction of interfaces to realize the exchange of intermediate data, and the reconfigurable sign handling approach will be explained, as well as a beneficial way to handle and distribute the numerous required control signals.

  14. The effect of retinal image error update rate on human vestibulo-ocular reflex gain adaptation.

    Science.gov (United States)

    Fadaee, Shannon B; Migliaccio, Americo A

    2016-04-01

    The primary function of the angular vestibulo-ocular reflex (VOR) is to stabilise images on the retina during head movements. Retinal image movement is the likely feedback signal that drives VOR modification/adaptation for different viewing contexts. However, it is not clear whether a retinal image position or velocity error is used primarily as the feedback signal. Recent studies examining this signal are limited because they used near viewing to modify the VOR. However, it is not known whether near viewing drives VOR adaptation or is a pre-programmed contextual cue that modifies the VOR. Our study is based on analysis of the VOR evoked by horizontal head impulses during an established adaptation task. Fourteen human subjects underwent incremental unilateral VOR adaptation training and were tested using the scleral search coil technique over three separate sessions. The update rate of the laser target position (source of the retinal image error signal) used to drive VOR adaptation was different for each session [50 (once every 20 ms), 20 and 15/35 Hz]. Our results show unilateral VOR adaptation occurred at 50 and 20 Hz for both the active (23.0 ± 9.6 and 11.9 ± 9.1% increase on adapting side, respectively) and passive VOR (13.5 ± 14.9, 10.4 ± 12.2%). At 15 Hz, unilateral adaptation no longer occurred in the subject group for both the active and passive VOR, whereas individually, 4/9 subjects tested at 15 Hz had significant adaptation. Our findings suggest that 1-2 retinal image position error signals every 100 ms (i.e. target position update rate 15-20 Hz) are sufficient to drive VOR adaptation. PMID:26715411

  15. The effect of retinal image error update rate on human vestibulo-ocular reflex gain adaptation.

    Science.gov (United States)

    Fadaee, Shannon B; Migliaccio, Americo A

    2016-04-01

    The primary function of the angular vestibulo-ocular reflex (VOR) is to stabilise images on the retina during head movements. Retinal image movement is the likely feedback signal that drives VOR modification/adaptation for different viewing contexts. However, it is not clear whether a retinal image position or velocity error is used primarily as the feedback signal. Recent studies examining this signal are limited because they used near viewing to modify the VOR. However, it is not known whether near viewing drives VOR adaptation or is a pre-programmed contextual cue that modifies the VOR. Our study is based on analysis of the VOR evoked by horizontal head impulses during an established adaptation task. Fourteen human subjects underwent incremental unilateral VOR adaptation training and were tested using the scleral search coil technique over three separate sessions. The update rate of the laser target position (source of the retinal image error signal) used to drive VOR adaptation was different for each session [50 (once every 20 ms), 20 and 15/35 Hz]. Our results show unilateral VOR adaptation occurred at 50 and 20 Hz for both the active (23.0 ± 9.6 and 11.9 ± 9.1% increase on adapting side, respectively) and passive VOR (13.5 ± 14.9, 10.4 ± 12.2%). At 15 Hz, unilateral adaptation no longer occurred in the subject group for both the active and passive VOR, whereas individually, 4/9 subjects tested at 15 Hz had significant adaptation. Our findings suggest that 1-2 retinal image position error signals every 100 ms (i.e. target position update rate 15-20 Hz) are sufficient to drive VOR adaptation.

  16. Adaptation to changes in vertical display gain during handwriting in Parkinson's disease patients, elderly and young controls.

    Science.gov (United States)

    Contreras-Vidal, José L; Teulings, Hans Leo; Stelmach, George E; Adler, Charles H

    2002-12-01

    Parkinson's disease (PD) patients, matched elderly controls, and normal young subjects were tested using a visuo-motor adaptation paradigm in which the gain of the vertical component of the visual feedback of handwriting was manipulated in real-time. Handwriting was performed on a digitizer tablet and displayed in real-time on a computer screen in front of the participant. Vision of the hand and pen was occluded. Feedback could be normal (pre- and post-exposure conditions), smaller, or larger than the actual handwriting (exposure conditions). All groups showed a gradual adaptation that compensated for the distorted visual feedback during the exposure conditions. Moreover, all the groups showed significant after-effects during the post-exposure conditions suggesting that all the participants learned to compensate for the novel display gains. Taken together, these data suggest that the mechanisms for visuo-motor adaptation to changes in vertical display gain during handwriting are robust to aging and early stage of PD. These results may have implications for the treatment of micrographia in Parkinsonism. PMID:12473396

  17. History-based Adaptive Modulation for a Downlink Multicast Channel in OFDMA systems

    DEFF Research Database (Denmark)

    Wang, Haibo; Schwefel, Hans-Peter; Toftegaard, Thomas Skjødeberg

    2008-01-01

    In this paper we investigated the adaptive modulation strategies for Multicast service in orthogonal frequency division multiple access systems. We defined a Reward function as the performance optimization target and developed adaptive modulation strategies to maximize this Reward function. The p...

  18. Ultrafast gain recovery and modulation limitations in self-assembled quantum-dot devices

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Bischoff, Svend; Magnúsdóttir, Ingibjörg;

    2001-01-01

    Measurements of ultrafast gain recovery in self-assembled InAs quantum-dot (QD) amplifiers are explained by a comprehensive numerical model. The on excited state carriers are found to act as a reservoir for the optically active ground state carriers resulting in an ultrafast gain recovery as long...

  19. A novel adaptive classification scheme for digital modulations in satellite communication

    Institute of Scientific and Technical Information of China (English)

    Wu Dan; Gu Xuemai; Guo Qing

    2007-01-01

    To make the modulation classification system more suitable for signals in a wide range of signal to noise ratios (SNRs) , a novel adaptive modulation classification scheme is presented in this paper. Different from traditional schemes, the proposed scheme employs a new SNR estimation algorithm for small samples before modulation classification, which makes the modulation classifier work adaptively according to estimated SNRs. Furthermore, it uses three efficient features and support vector machines (SVM) in modulation classification. Computer simulation shows that the scheme can adaptively classify ten digital modulation types (i.e. 2ASK, 4ASK, 2FSK, 4FSK, 2PSK, 4PSK, 16QAM, TFM, π/4QPSK and OQPSK) at SNRS ranging from OdB to 25 dB and success rates are over 95% when SNR is not lower than 3dB. Accuracy, efficiency and simplicity of the proposed scheme are obviously improved, which make it more adaptive to engineering applications.

  20. 40 Gb/s Pulse Generation Using Gain Switching of a Commercially Available Laser Module

    DEFF Research Database (Denmark)

    Nørregaard, Jesper; Hanberg, Jesper; Franck, Thorkild;

    1999-01-01

    , and a photodiode for optical power monitoring.The RF input port was connected to the driver circuit using a coplanar microwave probe. A DC bias and a large signal modulation at 10 GHz was applied to the module to generate chirped pulses. A linear as well as a non-linear soliton compression was used with optical...

  1. Robust adaptive controller design for a class of nonlinear systems with unknown high frequency gains

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this note, a robust adaptive control scheme is proposed for a class of nonlinear systems that have unknown multiplicative terms. Unlike previous results, except for the unknown control directions, we do not require a priori bounds on the unknown parameters. We also allow the unknown parameters to be time-varying provided that they are bounded. Our proposed robust adaptive controller is designed to identify on-line the unknown control directions and is a switching type controller, in which the controller parameters are tuned in a switching manner via a switching logic. Global stability of the closed-loop systems have been proved.

  2. Adapting Interpersonal Psychotherapy for the Prevention of Excessive Weight Gain in Rural African American Girls

    OpenAIRE

    Cassidy, Omni; Sbrocco, Tracy; Vannucci, Anna; Nelson, Beatrice; Jackson-Bowen, Darlene; Heimdal, James; Mirza, Nazrat; Wilfley, Denise E.; Osborn, Robyn; Shomaker, Lauren B.; Young, Jami F.; Waldron, Heather; Carter, Michele; Tanofsky-Kraff, Marian

    2013-01-01

    Objective To obtain focus group data regarding the perspectives of rural African American (AA) girls, parents/guardians, and community leaders on obesity, loss of control (LOC) eating, relationships, and interpersonal psychotherapy for the prevention of excessive weight gain (IPT-WG). Methods 7 focus groups (N = 50 participants) were moderated and the transcripts analyzed by Westat researchers using widely accepted methods of qualitative and thematic analysis. A session was held with experts ...

  3. Different gain/loss sensitivity and social adaptation ability in gifted adolescents during a public goods game.

    Science.gov (United States)

    Chung, Dongil; Yun, Kyongsik; Kim, Jin Ho; Jang, Bosun; Jeong, Jaeseung

    2011-02-16

    Gifted adolescents are considered to have high IQs with advanced mathematical and logical performances, but are often thought to suffer from social isolation or emotional mal-adaptation to the social group. The underlying mechanisms that cause stereotypic portrayals of gifted adolescents are not well known. We aimed to investigate behavioral performance of gifted adolescents during social decision-making tasks to assess their affective and social/non-social cognitive abilities. We examined cooperation behaviors of 22 gifted and 26 average adolescents during an iterative binary public goods (PG) game, a multi-player social interaction game, and analyzed strategic decision processes that include cooperation and free-riding. We found that the gifted adolescents were more cooperative than average adolescents. Particularly, comparing the strategies for the PG game between the two groups, gifted adolescents were less sensitive to loss, yet were more sensitive to gain. Additionally, the behavioral characteristics of average adolescents, such as low trust of the group and herding behavior, were not found in gifted adolescents. These results imply that gifted adolescents have a high cognitive ability but a low ability to process affective information or to adapt in social groups compared with average adolescents. We conclude that gain/loss sensitivity and the ability to adapt in social groups develop to different degrees in average and gifted adolescents.

  4. Different gain/loss sensitivity and social adaptation ability in gifted adolescents during a public goods game.

    Directory of Open Access Journals (Sweden)

    Dongil Chung

    Full Text Available Gifted adolescents are considered to have high IQs with advanced mathematical and logical performances, but are often thought to suffer from social isolation or emotional mal-adaptation to the social group. The underlying mechanisms that cause stereotypic portrayals of gifted adolescents are not well known. We aimed to investigate behavioral performance of gifted adolescents during social decision-making tasks to assess their affective and social/non-social cognitive abilities. We examined cooperation behaviors of 22 gifted and 26 average adolescents during an iterative binary public goods (PG game, a multi-player social interaction game, and analyzed strategic decision processes that include cooperation and free-riding. We found that the gifted adolescents were more cooperative than average adolescents. Particularly, comparing the strategies for the PG game between the two groups, gifted adolescents were less sensitive to loss, yet were more sensitive to gain. Additionally, the behavioral characteristics of average adolescents, such as low trust of the group and herding behavior, were not found in gifted adolescents. These results imply that gifted adolescents have a high cognitive ability but a low ability to process affective information or to adapt in social groups compared with average adolescents. We conclude that gain/loss sensitivity and the ability to adapt in social groups develop to different degrees in average and gifted adolescents.

  5. FPGA-based rate-adaptive LDPC-coded modulation for the next generation of optical communication systems.

    Science.gov (United States)

    Zou, Ding; Djordjevic, Ivan B

    2016-09-01

    In this paper, we propose a rate-adaptive FEC scheme based on LDPC codes together with its software reconfigurable unified FPGA architecture. By FPGA emulation, we demonstrate that the proposed class of rate-adaptive LDPC codes based on shortening with an overhead from 25% to 42.9% provides a coding gain ranging from 13.08 dB to 14.28 dB at a post-FEC BER of 10-15 for BPSK transmission. In addition, the proposed rate-adaptive LDPC coding combined with higher-order modulations have been demonstrated including QPSK, 8-QAM, 16-QAM, 32-QAM, and 64-QAM, which covers a wide range of signal-to-noise ratios. Furthermore, we apply the unequal error protection by employing different LDPC codes on different bits in 16-QAM and 64-QAM, which results in additional 0.5dB gain compared to conventional LDPC coded modulation with the same code rate of corresponding LDPC code. PMID:27607718

  6. Monolithically integrated quantum dot optical gain modulator with semiconductor optical amplifier for 10-Gb/s photonic transmission

    Science.gov (United States)

    Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Kawanishi, Tetsuya

    2015-03-01

    Short-range interconnection and/or data center networks require high capacity and a large number of channels in order to support numerous connections. Solutions employed to meet these requirements involve the use of alternative wavebands to increase the usable optical frequency range. We recently proposed the use of the T- and O-bands (Thousand band: 1000-1260 nm, Original band: 1260-1360 nm) as alternative wavebands because large optical frequency resources (>60 THz) can be easily employed. In addition, a simple and compact Gb/s-order high-speed optical modulator is a critical photonic device for short-range communications. Therefore, to develop an optical modulator that acts as a highfunctional photonic device, we focused on the use of self-assembled quantum dots (QDs) as a three-dimensional (3D) confined structure because QD structures are highly suitable for realizing broadband optical gain media in the T+O bands. In this study, we use the high-quality broadband QD optical gain to develop a monolithically integrated QD optical gain modulator (QD-OGM) device that has a semiconductor optical amplifier (QD-SOA) for Gb/s-order highspeed optical data generation in the 1.3-μm waveband. The insertion loss of the device can be compensated through the SOA, and we obtained an optical gain change of up to ~7 dB in the OGM section. Further, we successfully demonstrate a 10-Gb/s clear eye opening using the QD-OGM/SOA device with a clock-data recovery sequence at the receiver end. These results suggest that the monolithic QD-EOM/SOA is suitable for increasing the number of wavelength channels for smart short-range communications.

  7. Loss of Afferent Vestibular Input Produces Central Adaptation and Increased Gain of Vestibular Prosthetic Stimulation.

    Science.gov (United States)

    Phillips, Christopher; Shepherd, Sarah J; Nowack, Amy; Nie, Kaibao; Kaneko, Chris R S; Rubinstein, Jay T; Ling, Leo; Phillips, James O

    2016-02-01

    Implanted vestibular neurostimulators are effective in driving slow phase eye movements in monkeys and humans. Furthermore, increases in slow phase velocity and electrically evoked compound action potential (vECAP) amplitudes occur with increasing current amplitude of electrical stimulation. In intact monkeys, protracted intermittent stimulation continues to produce robust behavioral responses and preserved vECAPs. In lesioned monkeys, shorter duration studies show preserved but with somewhat lower or higher velocity behavioral responses. It has been proposed that such changes are due to central adaptive changes in the electrically elicited vestibulo-ocular reflex (VOR). It is equally possible that these differences are due to changes in the vestibular periphery in response to activation of the vestibular efferent system. In order to investigate the site of adaptive change in response to electrical stimulation, we performed transtympanic gentamicin perfusions to induce rapid changes in vestibular input in monkeys with long-standing stably functioning vestibular neurostimulators, disambiguating the effects of implantation from the effects of ototoxic lesion. Gentamicin injection was effective in producing a large reduction in natural VOR only when it was performed in the non-implanted ear, suggesting that the implanted ear contributed little to the natural rotational response before injection. Injection of the implanted ear produced a reduction in the vECAP responses in that ear, suggesting that the intact hair cells in the non-functional ipsilateral ear were successfully lesioned by gentamicin, reducing the efficacy of stimulation in that ear. Despite this, injection of both ears produced central plastic changes that resulted in a dramatically increased slow phase velocity nystagmus elicited by electrical stimulation. These results suggest that loss of vestibular afferent activity, and a concurrent loss of electrically elicited vestibular input, produces an

  8. Marriage, adaptation and happiness: Are there long-lasting gains to marriage?

    OpenAIRE

    Qari, Salmai

    2010-01-01

    This paper uses 23 waves of German panel data and investigates if individuals who decide to marry become permanently happier. Following the same persons over several years we show that they do, thereby challenging a number of recent longitudinal studies in psychology and economics which suggest that individuals fully adapt to the positive impact of marriage. We then convert the estimates into Euro values. It is well known that most newlyweds experience a 'honeymoon period' shortly after marri...

  9. High-gain adaptive regulator for a string equation with uncertain harmonic disturbance under boundary output feedback control

    Institute of Scientific and Technical Information of China (English)

    Baozhu GUO; Wei GUO

    2003-01-01

    This paper considers the boundary stabilization and parameter estimation of a one-dimensional wave equation in the case when one end is fixed and control and harmonic disturbance with uncertain amplitude are input at another end. A high-gain adaptive regulator is designed in terms of measured collocated end velocity. The existence and uniqueness of the classical solution of the closed-loop system is proven. It is shown that the state of the system approaches the standstill as time goes to infitv and meanwhile, the estimated parameter converges to the unknown parameter.

  10. Adaptive Gain and Analog Wavelet Transform for Low-Power Infrared Image Sensors

    Directory of Open Access Journals (Sweden)

    P. Villard

    2012-01-01

    Full Text Available A decorrelation and analog-to-digital conversion scheme aiming to reduce the power consumption of infrared image sensors is presented in this paper. To exploit both intraframe redundancy and inherent photon shot noise characteristics, a column based 1D Haar analog wavelet transform combined with variable gain amplification prior to A/D conversion is used. This allows to use only an 11-bit ADC, instead of a 13-bit one, and to save 15% of data transfer. An 8×16 pixels test circuit demonstrates this functionality.

  11. Adaptive Gain and Analog Wavelet Transform for Low-Power Infrared Image Sensors

    OpenAIRE

    Decaens, G.; Sicard, G.; Belleville, M; Thabuis, T.; P. Villard; Zecri, M.

    2012-01-01

    A decorrelation and analog-to-digital conversion scheme aiming to reduce the power consumption of infrared image sensors is presented in this paper. To exploit both intraframe redundancy and inherent photon shot noise characteristics, a column based 1D Haar analog wavelet transform combined with variable gain amplification prior to A/D conversion is used. This allows to use only an 11-bit ADC, instead of a 13-bit one, and to save 15% of data transfer. An 8 × 1 6 pixels test circuit demonstrat...

  12. Exploiting the gain-modulation mechanism in parieto-motor neurons: application to visuomotor transformations and embodied simulation.

    Science.gov (United States)

    Mahé, Sylvain; Braud, Raphaël; Gaussier, Philippe; Quoy, Mathias; Pitti, Alexandre

    2015-02-01

    The so-called self-other correspondence problem in imitation demands to find the transformation that maps the motor dynamics of one partner to our own. This requires a general purpose sensorimotor mechanism that transforms an external fixation-point (partner's shoulder) reference frame to one's own body-centered reference frame. We propose that the mechanism of gain-modulation observed in parietal neurons may generally serve these types of transformations by binding the sensory signals across the modalities with radial basis functions (tensor products) on the one hand and by permitting the learning of contextual reference frames on the other hand. In a shoulder-elbow robotic experiment, gain-field neurons (GF) intertwine the visuo-motor variables so that their amplitude depends on them all. In situations of modification of the body-centered reference frame, the error detected in the visuo-motor mapping can serve then to learn the transformation between the robot's current sensorimotor space and the new one. These situations occur for instance when we turn the head on its axis (visual transformation), when we use a tool (body modification), or when we interact with a partner (embodied simulation). Our results defend the idea that the biologically-inspired mechanism of gain modulation found in parietal neurons can serve as a basic structure for achieving nonlinear mapping in spatial tasks as well as in cooperative and social functions.

  13. Modulation of allele leakiness and adaptive mutability in Escherichia coli

    Indian Academy of Sciences (India)

    R. Jayaraman

    2000-08-01

    It is shown that partial phenotypic suppression of two ochre mutations (argE3 and lacZU118) and an amber mutation (in argE) by sublethal concentrations of streptomycin in an rpsL+ (streptomycin-sensitive) derivative of the Escherichia coli strain AB1157 greatly enhances their adaptive mutability under selection. Streptomycin also increases adaptive mutability brought about by the ppm mutation described earlier. Inactivation of recA affects neither phenotypic suppression by streptomycin nor replication-associated mutagenesis but abolishes adaptive mutagenesis. These results indicate a causal relationship between allele leakiness and adaptive mutability.

  14. Adaptive Modulation with Channel Estimation in High-Speed Packet-Based OFDM Communication Systems

    Institute of Scientific and Technical Information of China (English)

    HOU Xiao-lin; WU Jun-li; YIN Chang-chuan; YUE Guang-xin

    2004-01-01

    In this paper, adaptive modulation with channel estimation in high-speed packet-based Orthogonal Frequency Division Multiplexing (OFDM) communication systems for beyond 3G are discussed. Different adaptive modulation and channel estimation methods are presented and compared, then those methods suitable for our intended application are chosen. Conclusions can be drawn from computer simulations that with proper selection of packet length and subband width, wide subband adaptive modulation with Least Square plus Discrete-time Fourier Transform (LS-DFT) channel estimation can give an acceptable performance with low complexity for channel with low Doppler shift and small path delay. Otherwise, narrow subband or subcarrier adaptive modulation together with LS-DFT plus Decision Directed (LS-DFT-DD) must be used.

  15. Reduction of pattern effects in SOA-based all-optical switches by using cross-gain modulated holding signal

    DEFF Research Database (Denmark)

    Bischoff, Svend; Mørk, Jesper

    2002-01-01

    The effective carrier lifetime of SOAs is typically shortened by an intense Continuous Wave (CW) holding signal. However, the SOA gain is reduced by the holding signal resulting in smaller gain and refractive index changes induced by the data signal. Accordingly, an optimum exists for the CW...... and data signal power. Here, we demonstrate that the modulation bandwidth (amplitude jitter) is significantly improved (reduced) by replacing the CW holding beam with a signal, which is low-pass filtered and inverted with respect to the data signal. Such a holding beam can be generated by XGM WC in an SOA......, and reduces the fluctuations of the total energy injected into the interferometer within a bit-slot. Thus, we demonstrate a technique for reducing pattern effects in SOAs by employing a partially inverted holding beam. The method should be useful for increasing the data rates of all-optical switches....

  16. Distributed adaptive output consensus control of second-order systems containing unknown non-linear control gains

    Science.gov (United States)

    Wang, Gang; Wang, Chaoli; Du, Qinghui; Cai, Xuan

    2016-10-01

    In this paper, we address the output consensus problem of tracking a desired trajectory for a group of second-order agents on a directed graph with a fixed topology. Each agent is modelled by a second-order non-linear system with unknown non-linear dynamics and unknown non-linear control gains. Only a subset of the agents is given access to the desired trajectory information directly. A distributed adaptive consensus protocol driving all agents to track the desired trajectory is presented using the backstepping technique and approximation technique of Fourier series (FSs). The FS structure is taken not only for tracking the non-linear dynamics but also the unknown portion in the controller design procedure, which can avoid virtual controllers containing the uncertain terms. Stability analysis and parameter convergence of the proposed algorithm are conducted based on the Lyapunov theory and the algebraic graph theory. It is also demonstrated that arbitrary small tracking errors can be achieved by appropriately choosing design parameters. Though the proposed work is applicable for second-order non-linear systems containing unknown non-linear control gains, the proposed controller design can be easily extended to higher-order non-linear systems containing unknown non-linear control gains. Simulation results show the effectiveness of the proposed schemes.

  17. Adaptive gain, equalization, and wavelength stabilization techniques for silicon photonic microring resonator-based optical receivers

    Science.gov (United States)

    Palermo, Samuel; Chiang, Patrick; Yu, Kunzhi; Bai, Rui; Li, Cheng; Chen, Chin-Hui; Fiorentino, Marco; Beausoleil, Ray; Li, Hao; Shafik, Ayman; Titriku, Alex

    2016-03-01

    Interconnect architectures based on high-Q silicon photonic microring resonator devices offer a promising solution to address the dramatic increase in datacenter I/O bandwidth demands due to their ability to realize wavelength-division multiplexing (WDM) in a compact and energy efficient manner. However, challenges exist in realizing efficient receivers for these systems due to varying per-channel link budgets, sensitivity requirements, and ring resonance wavelength shifts. This paper reports on adaptive optical receiver design techniques which address these issues and have been demonstrated in two hybrid-integrated prototypes based on microring drop filters and waveguide photodetectors implemented in a 130nm SOI process and high-speed optical front-ends designed in 65nm CMOS. A 10Gb/s powerscalable architecture employs supply voltage scaling of a three inverter-stage transimpedance amplifier (TIA) that is adapted with an eye-monitor control loop to yield the necessary sensitivity for a given channel. As reduction of TIA input-referred noise is more critical at higher data rates, a 25Gb/s design utilizes a large input-stage feedback resistor TIA cascaded with a continuous-time linear equalizer (CTLE) that compensates for the increased input pole. When tested with a waveguide Ge PD with 0.45A/W responsivity, this topology achieves 25Gb/s operation with -8.2dBm sensitivity at a BER=10-12. In order to address microring drop filters sensitivity to fabrication tolerances and thermal variations, efficient wavelength-stabilization control loops are necessary. A peak-power-based monitoring loop which locks the drop filter to the input wavelength, while achieving compatibility with the high-speed TIA offset-correction feedback loop is implemented with a 0.7nm tuning range at 43μW/GHz efficiency.

  18. Tunable true-time delay of a microwave photonic signal realized by cross gain modulation in a semiconductor waveguide

    DEFF Research Database (Denmark)

    Xue, Weiqi; Mørk, Jesper

    2011-01-01

    We experimentally demonstrate the realization of a tunable true-time delay for microwave signals by exploiting cross gain modulation among counter-propagating optical beams in a semiconductor optical amplifier. Broadband operation from ∼5 to ∼35 GHz is observed. The physical effect originates from...... the combination of carrier dynamics and propagation effects, and the experimental results are well accounted for by a numerical model. We find that, in contrast to the case of the co-propagating beams, the bandwidth is not limited by the lifetime of excited carriers. The trade-off between the magnitude...

  19. Cross-layer combining of power control and adaptive modulation with truncated ARQ for cognitive radios

    Institute of Scientific and Technical Information of China (English)

    CHENG Shi-lun; YANG Zhen

    2008-01-01

    To maximize throughput and to satisfy users' requirements in cognitive radios, a cross-layer optimization problem combining adaptive modulation and power control at the physical layer and truncated automatic repeat request at the medium access control layer is proposed. Simulation results show the combination of power control, adaptive modulation, and truncated automatic repeat request can regulate transmitter powers and increase the total throughput effectively.

  20. Distributed cerebellar plasticity implements adaptable gain control in a manipulation task: a closed-loop robotic simulation

    Directory of Open Access Journals (Sweden)

    Jesus A Garrido Alcazar

    2013-10-01

    Full Text Available Adaptable gain regulation is at the core of the forward controller operation performed by the cerebro-cerebellar loops and it allows the intensity of motor acts to be finely tuned in a predictive manner. In order to learn and store information about body-object dynamics and to generate an internal model of movement, the cerebellum is thought to employ long-term synaptic plasticity. LTD at the PF-PC synapse has classically been assumed to subserve this function (Marr, 1969. However, this plasticity alone cannot account for the broad dynamic ranges and time scales of cerebellar adaptation. We therefore tested the role of plasticity distributed over multiple synaptic sites (Gao et al., 2012; Hansel et al., 2001 by generating an analog cerebellar model embedded into a control loop connected to a robotic simulator. The robot used a three-joint arm and performed repetitive fast manipulations with different masses along an 8-shape trajectory. In accordance with biological evidence, the cerebellum model was endowed with both LTD and LTP at the PF-PC, MF-DCN and PC-DCN synapses. This resulted in a network scheme whose effectiveness was extended considerably compared to one including just PF-PC synaptic plasticity. Indeed, the system including distributed plasticity reliably self-adapted to manipulate different masses and to learn the arm-object dynamics over a time course that included fast learning and consolidation, along the lines of what has been observed in behavioral tests. In particular, PF-PC plasticity operated as a time correlator between the actual input state and the system error, while MF-DCN and PC-DCN plasticity played a key role in generating the gain controller. This model suggests that distributed synaptic plasticity allows generation of the complex learning properties of the cerebellum. The incorporation of further plasticity mechanisms and of spiking signal processing will allow this concept to be extended in a more realistic

  1. Wireless Local Area Network Adaptive Modulation and Coding Technology Research

    Institute of Scientific and Technical Information of China (English)

    SUN Zeng-you; SUN Xiao-fan

    2012-01-01

      Expound the existing modulation mode of the present wireless local area network. Directing at the problem that when single modulation method conveys data with high speed in the frequency selective fading channel, the system throughput will be declined and the efficiency of the spectrum will be lowered . Put forward the scheme that the OFDM sub-carrier will use differ⁃ent modulation modes after dynamic groups by amplitude frequency response. Simulation results show that the scheme will lower the complexity of the system achievement, and can get a higher spectrum efficiency.

  2. Prestimulus neural oscillations inhibit visual perception via modulation of response gain.

    Science.gov (United States)

    Chaumon, Maximilien; Busch, Niko A

    2014-11-01

    The ongoing state of the brain radically affects how it processes sensory information. How does this ongoing brain activity interact with the processing of external stimuli? Spontaneous oscillations in the alpha range are thought to inhibit sensory processing, but little is known about the psychophysical mechanisms of this inhibition. We recorded ongoing brain activity with EEG while human observers performed a visual detection task with stimuli of different contrast intensities. To move beyond qualitative description, we formally compared psychometric functions obtained under different levels of ongoing alpha power and evaluated the inhibitory effect of ongoing alpha oscillations in terms of contrast or response gain models. This procedure opens the way to understanding the actual functional mechanisms by which ongoing brain activity affects visual performance. We found that strong prestimulus occipital alpha oscillations-but not more anterior mu oscillations-reduce performance most strongly for stimuli of the highest intensities tested. This inhibitory effect is best explained by a divisive reduction of response gain. Ongoing occipital alpha oscillations thus reflect changes in the visual system's input/output transformation that are independent of the sensory input to the system. They selectively scale the system's response, rather than change its sensitivity to sensory information.

  3. A channel- and QoS-adaptive turbo coded modulation architecture for mobile multimedia communication

    Institute of Scientific and Technical Information of China (English)

    Zuo Jiancun; Song Wentao; Luo Hanwen; Xu Youyun

    2009-01-01

    This paper proposed a cross-layer dual adaptive coded modulation architecture using turbo codes for mobile multimedia communication, which simultaneously adapted to both the varying channel characteristics and the quality of service (QoS) of various mobile multimedia services to increase the average system throughput substantially. A pragmatic channel-adaptive turbo coded modulation scheme, which comes within 2.5dB of the Shannon limit, was optimally designed, and then a QoS-adaptive scheme was superimposed to build the dual adaptive architecture. Simulation results show that the novel dual adaption reduces the difference with the fading channel capacity to 2dB when assuming different services occur in equal probability and the service duration follows the exponential distribution.

  4. Impact of gain compression factor on modulation characteristics of InGaAs/GaAs self-assembled quantum dot lasers

    Science.gov (United States)

    Kariminezhad, Farzaneh; Rajaei, Esfandiar; Fali, Alireza; Mirzaei, Reyhaneh

    2016-06-01

    This paper investigates the influence of gain compression factor on the modulation response of InGaAs/GaAs self-assembled quantum dot laser based on rate equations. For different gain compression factors the output power-current characteristics, light emissions of quantum dot laser have been simulated and effect of gain compression factor changes on quantum dot laser is illustrated. Also, small and large-signal response of quantum dot lasers is studied and the impact of the gain compression factor is presented. It explains that increase of gain compression factor, decreases small-signal modulation characteristics, nevertheless, improves large-signal response of quantum dot lasers. It helps to generate better laser signal quality, higher eye and smaller jitter. The large-signal behavior of a laser diode determines its capability for digital data transfer. The modulation speed of quantum dot lasers is of specific importance if such lasers are considered for optical communication systems.

  5. Analytical evaluation of adaptive-modulation-based opportunistic cognitive radio in nakagami-m fading channels

    KAUST Repository

    Chen, Yunfei

    2012-09-01

    The performance of adaptive modulation for cognitive radio with opportunistic access is analyzed by considering the effects of spectrum sensing, primary user (PU) traffic, and time delay for Nakagami- m fading channels. Both the adaptive continuous rate scheme and the adaptive discrete rate scheme are considered. Numerical examples are presented to quantify the effects of spectrum sensing, PU traffic, and time delay for different system parameters. © 1967-2012 IEEE.

  6. Adaptive capacity to bacterial diet modulates aging in C. elegans

    OpenAIRE

    Pang, Shanshan; Curran, Sean P.

    2014-01-01

    Diet has a substantial impact on cellular metabolism and physiology. Animals must sense different food sources and utilize distinct strategies to adapt to diverse diets. Here we show that C. elegans lifespan is regulated by their adaptive capacity to different diets, which is controlled by alh-6, a conserved proline metabolism gene. alh-6 mutants age prematurely when fed an E. coli OP50 but not HT115 diet. Remarkably, this diet-dependent aging phenotype is determined by exposure to food durin...

  7. Achieving high-resolution soft-tissue imaging with cone-beam CT: a two-pronged approach for modulation of x-ray fluence and detector gain

    Science.gov (United States)

    Graham, S. A.; Siewerdsen, J. H.; Moseley, D. J.; Keller, H.; Shkumat, N. A.; Jaffray, D. A.

    2005-04-01

    Cone-beam computed tomography (CBCT) presents a highly promising and challenging advanced application of flat-panel detectors (FPDs). The great advantage of this adaptable technology is in the potential for sub-mm 3D spatial resolution in combination with soft-tissue detectability. While the former is achieved naturally by CBCT systems incorporating modern FPD designs (e.g., 200 - 400 um pixel pitch), the latter presents a significant challenge due to limitations in FPD dynamic range, large field of view, and elevated levels of x-ray scatter in typical CBCT configurations. We are investigating a two-pronged strategy to maximizing soft-tissue detectability in CBCT: 1) front-end solutions, including novel beam modulation designs (viz., spatially varying compensators) that alleviate detector dynamic range requirements, reduce x-ray scatter, and better distribute imaging dose in a manner suited to soft-tissue visualization throughout the field of view; and 2) back-end solutions, including implementation of an advanced FPD design (Varian PaxScan 4030CB) that features dual-gain and dynamic gain switching that effectively extends detector dynamic range to 18 bits. These strategies are explored quantitatively on CBCT imaging platforms developed in our laboratory, including a dedicated CBCT bench and a mobile isocentric C-arm (Siemens PowerMobil). Pre-clinical evaluation of improved soft-tissue visibility was carried out in phantom and patient imaging with the C-arm device. Incorporation of these strategies begin to reveal the full potential of CBCT for soft-tissue visualization, an essential step in realizing broad utility of this adaptable technology for diagnostic and image-guided procedures.

  8. Adaptive Jamming Suppression in Coherent FFH System Using Weighted Equal Gain Combining Receiver over Fading Channels with Imperfect CSI

    Directory of Open Access Journals (Sweden)

    Yishan He

    2015-01-01

    Full Text Available Fast frequency hopping (FFH is commonly used as an antijamming communication method. In this paper, we propose efficient adaptive jamming suppression schemes for binary phase shift keying (BPSK based coherent FFH system, namely, weighted equal gain combining (W-EGC with the optimum and suboptimum weighting coefficient. We analyze the bit error ratio (BER of EGC and W-EGC receivers with partial band noise jamming (PBNJ, frequency selective Rayleigh fading, and channel estimation errors. Particularly, closed-form BER expressions are presented with diversity order two. Our analysis is verified by simulations. It is shown that W-EGC receivers significantly outperform EGC. As compared to the maximum likelihood (ML receiver in conventional noncoherent frequency shift keying (FSK based FFH, coherent FFH/BPSK W-EGC receivers also show significant advantages in terms of BER. Moreover, W-EGC receivers greatly reduce the hostile jammers’ jamming efficiency.

  9. A novel adaptive modulation and coding strategy based on partial feedback for enhanced MBMS network

    Institute of Scientific and Technical Information of China (English)

    SHENG Yu; PENG Mu-gen; WANG Wen-bo

    2008-01-01

    The difference in link condition of broadcast/multicast users and the limitation of uplink resource, make itdifficult to utilize adaptive modulation and coding (AMC) in theenhanced multimedia broadcast and multicast service (E-MBMS)network. To obtain the improvement of system throughput, thisstudy proposes an adaptive modulation and coding schemebased on partial feedback, by which only partial users whosechannel qualities are lower than the system threshold need tomake a response to the modulation coding scheme (MCS)adaptation procedure. By this investigation, an adaptive schemecan be introduced in the E-MBMS network. Both the theoreticalanalysis and simulation results demonstrate the efficiency of theproposed strategy, in which the performance is close to the idealone and has a significant throughput improvement whencompared with that of the fixed MCS transmission scheme.

  10. A Module for Adaptive Course Configuration and Assessment in Moodle

    Science.gov (United States)

    Limongelli, Carla; Sciarrone, Filippo; Temperini, Marco; Vaste, Giulia

    Personalization and Adaptation are among the main challenges in the field of e-learning, where currently just few Learning Management Systems, mostly experimental ones, support such features. In this work we present an architecture that allows Moodle to interact with the Lecomps system, an adaptive learning system developed earlier by our research group, that has been working in a stand-alone modality so far. In particular, the Lecomps responsibilities are circumscribed to the sole production of personalized learning objects sequences and to the management of the student model, leaving to Moodle all the rest of the activities for course delivery. The Lecomps system supports the "dynamic" adaptation of learning objects sequences, basing on the student model, i.e., learner's Cognitive State and Learning Style. Basically, this work integrates two main Lecomps tasks into Moodle, to be directly managed by it: Authentication and Quizzes.

  11. An AC modulated near infrared gain calibration system for a "Violin-Mode" transimpedance amplifier, intended for advanced LIGO suspensions.

    Science.gov (United States)

    Lockerbie, N A; Tokmakov, K V

    2016-07-01

    The background to this work was a prototype shadow sensor, which was designed for retro-fitting to an advanced LIGO (Laser Interferometer Gravitational wave Observatory) test-mass/mirror suspension, in which a 40 kg test-mass/mirror is suspended by four approximately 600 mm long by 0.4 mm diameter fused-silica suspension fibres. The shadow sensor comprised a LED source of Near InfraRed (NIR) radiation, and a "tall-thin" rectangular silicon photodiode detector, which together were to bracket the fibre under test. The photodiode was positioned so as to be sensitive (primarily) to transverse "Violin-Mode" vibrations of such a fibre, via the oscillatory movement of the shadow cast by the fibre, as this moved across the face of the detector. In this prototype shadow sensing system the photodiode was interfaced to a purpose-built transimpedance amplifier, this having both AC and DC outputs. A quasi-static calibration was made of the sensor's DC responsivity, i.e., incremental rate of change of output voltage versus fibre position, by slowly scanning a fused-silica fibre sample transversely through the illuminating beam. The work reported here concerns the determination of the sensor's more important AC (Violin-Mode) responsivity. Recognition of the correspondence between direct AC modulation of the source, and actual Violin-Mode signals, and of the transformative role of the AC/DC gain ratio for the amplifier, at any modulation frequency, f, resulted in the construction of the AC/DC calibration source described here. A method for determining in practice the transimpedance AC/DC gain ratio of the photodiode and amplifier, using this source, is illustrated by a specific numerical example, and the gain ratio for the prototype sensing system is reported over the frequency range 1 Hz-300 kHz. In fact, a maximum DC responsivity of 1.26 kV.m(-1) was measured using the prototype photodiode sensor and amplifier discussed here. Therefore, the measured AC/DC transimpedance gain

  12. An AC modulated near infrared gain calibration system for a "Violin-Mode" transimpedance amplifier, intended for advanced LIGO suspensions.

    Science.gov (United States)

    Lockerbie, N A; Tokmakov, K V

    2016-07-01

    The background to this work was a prototype shadow sensor, which was designed for retro-fitting to an advanced LIGO (Laser Interferometer Gravitational wave Observatory) test-mass/mirror suspension, in which a 40 kg test-mass/mirror is suspended by four approximately 600 mm long by 0.4 mm diameter fused-silica suspension fibres. The shadow sensor comprised a LED source of Near InfraRed (NIR) radiation, and a "tall-thin" rectangular silicon photodiode detector, which together were to bracket the fibre under test. The photodiode was positioned so as to be sensitive (primarily) to transverse "Violin-Mode" vibrations of such a fibre, via the oscillatory movement of the shadow cast by the fibre, as this moved across the face of the detector. In this prototype shadow sensing system the photodiode was interfaced to a purpose-built transimpedance amplifier, this having both AC and DC outputs. A quasi-static calibration was made of the sensor's DC responsivity, i.e., incremental rate of change of output voltage versus fibre position, by slowly scanning a fused-silica fibre sample transversely through the illuminating beam. The work reported here concerns the determination of the sensor's more important AC (Violin-Mode) responsivity. Recognition of the correspondence between direct AC modulation of the source, and actual Violin-Mode signals, and of the transformative role of the AC/DC gain ratio for the amplifier, at any modulation frequency, f, resulted in the construction of the AC/DC calibration source described here. A method for determining in practice the transimpedance AC/DC gain ratio of the photodiode and amplifier, using this source, is illustrated by a specific numerical example, and the gain ratio for the prototype sensing system is reported over the frequency range 1 Hz-300 kHz. In fact, a maximum DC responsivity of 1.26 kV.m(-1) was measured using the prototype photodiode sensor and amplifier discussed here. Therefore, the measured AC/DC transimpedance gain

  13. An AC modulated near infrared gain calibration system for a "Violin-Mode" transimpedance amplifier, intended for advanced LIGO suspensions

    Science.gov (United States)

    Lockerbie, N. A.; Tokmakov, K. V.

    2016-07-01

    The background to this work was a prototype shadow sensor, which was designed for retro-fitting to an advanced LIGO (Laser Interferometer Gravitational wave Observatory) test-mass/mirror suspension, in which a 40 kg test-mass/mirror is suspended by four approximately 600 mm long by 0.4 mm diameter fused-silica suspension fibres. The shadow sensor comprised a LED source of Near InfraRed (NIR) radiation, and a "tall-thin" rectangular silicon photodiode detector, which together were to bracket the fibre under test. The photodiode was positioned so as to be sensitive (primarily) to transverse "Violin-Mode" vibrations of such a fibre, via the oscillatory movement of the shadow cast by the fibre, as this moved across the face of the detector. In this prototype shadow sensing system the photodiode was interfaced to a purpose-built transimpedance amplifier, this having both AC and DC outputs. A quasi-static calibration was made of the sensor's DC responsivity, i.e., incremental rate of change of output voltage versus fibre position, by slowly scanning a fused-silica fibre sample transversely through the illuminating beam. The work reported here concerns the determination of the sensor's more important AC (Violin-Mode) responsivity. Recognition of the correspondence between direct AC modulation of the source, and actual Violin-Mode signals, and of the transformative role of the AC/DC gain ratio for the amplifier, at any modulation frequency, f, resulted in the construction of the AC/DC calibration source described here. A method for determining in practice the transimpedance AC/DC gain ratio of the photodiode and amplifier, using this source, is illustrated by a specific numerical example, and the gain ratio for the prototype sensing system is reported over the frequency range 1 Hz-300 kHz. In fact, a maximum DC responsivity of 1.26 kV.m-1 was measured using the prototype photodiode sensor and amplifier discussed here. Therefore, the measured AC/DC transimpedance gain ratio

  14. It's not my fault: postdictive modulation of intentional binding by monetary gains and losses.

    Directory of Open Access Journals (Sweden)

    Keisuke Takahata

    Full Text Available Sense of agency refers to the feeling that one's voluntary actions caused external events. Past studies have shown that compression of the subjective temporal interval between actions and external events, called intentional binding, is closely linked to the experience of agency. Current theories postulate that the experience of agency is constructed via predictive and postdictive pathways. One remaining problem is the source of human causality bias; people often make misjudgments on the causality of voluntary actions and external events depending on their rewarding or punishing outcomes. Although human causality bias implies that sense of agency can be modified by post-action information, convincing empirical findings for this issue are lacking. Here, we hypothesized that sense of agency would be modified by affective valences of action outcomes. To examine this issue, we investigated how rewarding and punishing outcomes following voluntary action modulate behavioral measures of agency using intentional binding paradigm and classical conditioning procedures. In the acquisition phase, auditory stimuli were paired with positive, neutral or negative monetary outcomes. Tone-reward associations were evaluated using reaction times and preference ratings. In the experimental session, participants performed a variant of intentional binding task, where participants made timing judgments for onsets of actions and sensory outcomes while playing simple slot games. Our results showed that temporal binding was modified by affective valences of action outcomes. Specifically, intentional binding was attenuated when negative outcome occurred, consistent with self-serving bias. Our study not only provides evidence for postdictive modification of agency, but also proposes a possible mechanism of human causality bias.

  15. Adaptive capacity to bacterial diet modulates aging in C. elegans.

    Science.gov (United States)

    Pang, Shanshan; Curran, Sean P

    2014-02-01

    Diet has a substantial impact on cellular metabolism and physiology. Animals must sense different food sources and utilize distinct strategies to adapt to diverse diets. Here we show that Caenorhabditis elegans lifespan is regulated by their adaptive capacity to different diets, which is controlled by alh-6, a conserved proline metabolism gene. alh-6 mutants age prematurely when fed an Escherichia coli OP50 but not HT115 diet. Remarkably, this diet-dependent aging phenotype is determined by exposure to food during development. Mechanistically, the alh-6 mutation triggers diet-induced mitochondrial defects and increased generation of ROS, likely due to accumulation of its substrate 1-pyrroline-5-carboxylate. We also identify that neuromedin U receptor signaling is essential for diet-induced mitochondrial changes and premature aging. Moreover, dietary restriction requires alh-6 to induce longevity. Collectively, our data reveal a homeostatic mechanism that animals employ to cope with potential dietary insults and uncover an example of lifespan regulation by dietary adaptation. PMID:24440036

  16. ADAPTIVE MODULATION AND POWER CONTROL FOR THROUGHPUT ENHANCEMENT IN COGNITIVE RADIOS

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    To regulate the transmit-power and enhance the total throughput, a novel Transmit Power Control Game (TPCG) algorithm and an adaptive Modulation TPCG (M-TPCG) algorithm which combine bandwidth allocation, adaptive modulation and transmit-power control based on Space Time Block Coding (STBC) OFDM-CDMA system are designed and a cross-layer framework of database sharing is proposed. Simulation results show that the TPCG algorithm can regulate their transmitter powers and enhance the total throughput effectively, M-TPCG algorithm can achieve maximal system throughput. The performance of the cognitive radio system is improved obviously.

  17. An Adaptive Gain Nonlinear Observer for State of Charge Estimation of Lithium-Ion Batteries in Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Yong Tian

    2014-09-01

    Full Text Available The state of charge (SOC is important for the safety and reliability of battery operation since it indicates the remaining capacity of a battery. However, it is difficult to get an accurate value of SOC, because the SOC cannot be directly measured by a sensor. In this paper, an adaptive gain nonlinear observer (AGNO for SOC estimation of lithium-ion batteries (LIBs in electric vehicles (EVs is proposed. The second-order resistor–capacitor (2RC equivalent circuit model is used to simulate the dynamic behaviors of a LIB, based on which the state equations are derived to design the AGNO for SOC estimation. The model parameters are identified using the exponential-function fitting method. The sixth-order polynomial function is used to describe the highly nonlinear relationship between the open circuit voltage (OCV and the SOC. The convergence of the proposed AGNO is proved using the Lyapunov stability theory. Two typical driving cycles, including the New European Driving Cycle (NEDC and Federal Urban Driving Schedule (FUDS are adopted to evaluate the performance of the AGNO by comparing with the unscented Kalman filter (UKF algorithm. The experimental results show that the AGNO has better performance than the UKF algorithm in terms of reducing the computation cost, improving the estimation accuracy and enhancing the convergence ability.

  18. Performance analysis of joint diversity combining, adaptive modulation, and power control schemes

    KAUST Repository

    Qaraqe, Khalid A.

    2011-01-01

    Adaptive modulation and diversity combining represent very important adaptive solutions for future generations of wireless communication systems. Indeed, in order to improve the performance and the efficiency of these systems, these two techniques have been recently used jointly in new schemes named joint adaptive modulation and diversity combining (JAMDC) schemes. Considering the problem of finding low hardware complexity, bandwidth-efficient, and processing-power efficient transmission schemes for a downlink scenario and capitalizing on some of these recently proposed JAMDC schemes, we propose and analyze in this paper three joint adaptive modulation, diversity combining, and power control (JAMDCPC) schemes where a constant-power variable-rate adaptive modulation technique is used with an adaptive diversity combining scheme and a common power control process. More specifically, the modulation constellation size, the number of combined diversity paths, and the needed power level are jointly determined to achieve the highest spectral efficiency with the lowest possible processing power consumption quantified in terms of the average number of combined paths, given the fading channel conditions and the required bit error rate (BER) performance. In this paper, the performance of these three JAMDCPC schemes is analyzed in terms of their spectral efficiency, processing power consumption, and error-rate performance. Selected numerical examples show that these schemes considerably increase the spectral efficiency of the existing JAMDC schemes with a slight increase in the average number of combined paths for the low signal-to-noise ratio range while maintaining compliance with the BER performance and a low radiated power which yields to a substantial decrease in interference to co-existing users and systems. © 2011 IEEE.

  19. On the feedback error compensation for adaptive modulation and coding scheme

    KAUST Repository

    Choi, Seyeong

    2011-11-25

    In this paper, we consider the effect of feedback error on the performance of the joint adaptive modulation and diversity combining (AMDC) scheme which was previously studied with an assumption of perfect feedback channels. We quantify the performance of two joint AMDC schemes in the presence of feedback error, in terms of the average spectral efficiency, the average number of combined paths, and the average bit error rate. The benefit of feedback error compensation with adaptive combining is also quantified. Selected numerical examples are presented and discussed to illustrate the effectiveness of the proposed feedback error compensation strategy with adaptive combining. Copyright (c) 2011 John Wiley & Sons, Ltd.

  20. Performance analysis of two-way amplify and forward relaying with adaptive modulation over multiple relay network

    KAUST Repository

    Hwang, Kyusung

    2011-02-01

    In this letter, we propose two-way amplify-and-forward relaying in conjunction with adaptive modulation in order to improve spectral efficiency of relayed communication systems while monitoring the required error performance. We also consider a multiple relay network where only the best relay node is utilized so that the diversity order increases while maintaining a low complexity of implementation as the number of relays increases. Based on the best relay selection criterion, we offer an upper bound on the signal-to-noise ratio to keep the performance analysis tractable. Our numerical examples show that the proposed system offers a considerable gain in spectral efficiency while satisfying the error rate requirements. © 2011 IEEE.

  1. Muscle weakness and lack of reflex gain adaptation predominate during post-stroke posture control of the wrist

    Directory of Open Access Journals (Sweden)

    van der Helm Frans CT

    2009-07-01

    Full Text Available Abstract Background Instead of hyper-reflexia as sole paradigm, post-stroke movement disorders are currently considered the result of a complex interplay between neuronal and muscular properties, modified by level of activity. We used a closed loop system identification technique to quantify individual contributors to wrist joint stiffness during an active posture task. Methods Continuous random torque perturbations applied to the wrist joint by a haptic manipulator had to be resisted maximally. Reflex provoking conditions were applied i.e. additional viscous loads and reduced perturbation signal bandwidth. Linear system identification and neuromuscular modeling were used to separate joint stiffness into the intrinsic resistance of the muscles including co-contraction and the reflex mediated contribution. Results Compared to an age and sex matched control group, patients showed an overall 50% drop in intrinsic elasticity while their reflexive contribution did not respond to provoking conditions. Patients showed an increased mechanical stability compared to control subjects. Conclusion Post stroke, we found active posture tasking to be dominated by: 1 muscle weakness and 2 lack of reflex adaptation. This adds to existing doubts on reflex blocking therapy as the sole paradigm to improve active task performance and draws attention to muscle strength and power recovery and the role of the inability to modulate reflexes in post stroke movement disorders.

  2. The optimal configuration of photovoltaic module arrays based on adaptive switching controls

    International Nuclear Information System (INIS)

    Highlights: • We propose a strategy for determining the optimal configuration of a PV array. • The proposed strategy was based on particle swarm optimization (PSO) method. • It can identify the optimal module array connection scheme in the event of shading. • It can also find the optimal connection of a PV array even in module malfunctions. - Abstract: This study proposes a strategy for determining the optimal configuration of photovoltaic (PV) module arrays in shading or malfunction conditions. This strategy was based on particle swarm optimization (PSO). If shading or malfunctions of the photovoltaic module array occur, the module array immediately undergoes adaptive reconfiguration to increase the power output of the PV power generation system. First, the maximal power generated at various irradiation levels and temperatures was recorded during normal array operation. Subsequently, the irradiation level and module temperature, regardless of operating conditions, were used to recall the maximal power previously recorded. This previous maximum was compared with the maximal power value obtained using the maximum power point tracker to assess whether the PV module array was experiencing shading or malfunctions. After determining that the array was experiencing shading or malfunctions, PSO was used to identify the optimal module array connection scheme in abnormal conditions, and connection switches were used to implement optimal array reconfiguration. Finally, experiments were conducted to assess the strategy for identifying the optimal reconfiguration of a PV module array in the event of shading or malfunctions

  3. Adaptive Fraunhofer diffraction particle sizing instrument using a spatial light modulator.

    Science.gov (United States)

    Hirleman, E D; Dellenback, P A

    1989-11-15

    Integration of a magnetooptic spatial light modulator into a Fraunhofer diffraction particle sizing instrument is proposed and demonstrated theoretically and experimentally. The concept gives the instrument the ability to reconfigure a detector array on-line and thereby adapt to the measurement context. PMID:20555963

  4. Latency Considerations for Adaptive Modulation in an Interference-free Slow Rayleigh Fading Channel

    OpenAIRE

    Torrance, J; Hanzo, L.

    1997-01-01

    Adaptive modulation exploits the time-variant channel capacity uctuation of fading channels using a range of different modem modes according to Equation 1 and Table 1. This is achieved at the cost of some latency penalty, which is quantified in this treatise and mitigated by frequency hopping.

  5. Pulse oximeter using a gain-modulated avalanche photodiode operated in a pseudo lock-in light detection mode

    Science.gov (United States)

    Miyata, Tsuyoshi; Iwata, Tetsuo; Araki, Tsutomu

    2006-01-01

    We propose a reflection-type pulse oximeter, which employs two pairs of a light-emitting diode (LED) and a gated avalanche photodiode (APD). One LED is a red one with an emission wavelength λ = 635 nm and the other is a near-infrared one with that λ = 945 nm, which are both driven with a pulse mode at a frequency f (=10 kHz). Superposition of a transistor-transistor-logic (TTL) gate pulse on a direct-current (dc) bias, which is set so as not exceeding the breakdown voltage of each APD, makes the APD work in a gain-enhanced operation mode. Each APD is gated at a frequency 2f (=20 kHz) and its output signal is fed into a laboratory-made lock-in amplifier that works in synchronous with the pulse modulation signal of each LED at a frequency f (=10 kHz). A combination of the gated APD and the lock-in like signal detection scheme is useful for the reflection-type pulse oximeter thanks to the capability of detecting a weak signal against a large background (BG) light.

  6. Association between presence in lectures and student knowledge gain in problem based learning: experience in Neuropsychiatry module, FMUI, International Program

    Directory of Open Access Journals (Sweden)

    Jeanne A. Pawitan

    2009-06-01

    Full Text Available Aim This study was conducted to determine the association between presence in lecture and examination scores.Methods This was a cross sectional study, conducted in the Faculty of Medicine University of Indonesia, International Class Program, from November 2007 to May 2008. The subject’s inclusion criterion was FMUI International class students enrolled in the Neuropsychiatry module in 2007/2008. we excluded students who did not attend the examinations i.e. multiple choice questions (MCQ-1, -2, or essay. The data collected were presence in lecture and examination scores. Data analysis was done using SPSS linear regression to see the association between presence in lectures and exam scores.Results The results showed that the R and P of the association between presence in lectures and exam scores were (R= 0.121, P= 0.413, (R= 0.212, P= 0.148, (R= 0.260, P= 0.075, and (R= 0.280, P= 0.054 for MCQ1, MCQ2, essay, and mean exam scores respectively.Conclusion We failed to show the association between presence in lectures and student knowledge gain. This result might be due to the many factors discussed that were not analyzed in this study. (Med J Indones 2008; 18: 131-4Key words: exam, MCQ, essay

  7. Dosimetric effects of weight loss or gain during volumetric modulated arc therapy and intensity-modulated radiation therapy for prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Pair, Matthew L. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Du, Weiliang [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Rojas, Hector D.; Kanke, James E.; McGuire, Sean E.; Lee, Andrew K.; Kuban, Deborah A. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Kudchadker, Rajat J., E-mail: rkudchad@mdanderson.org [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX (United States)

    2013-10-01

    Weight loss or gain during the course of radiation therapy for prostate cancer can alter the planned dose to the target volumes and critical organs. Typically, source-to-surface distance (SSD) measurements are documented by therapists on a weekly basis to ensure that patients' exterior surface and isocenter-to-skin surface distances remain stable. The radiation oncology team then determines whether the patient has undergone a physical change sufficient to require a new treatment plan. The effect of weight change (SSD increase or decrease) on intensity-modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT) dosimetry is not well known, and it is unclear when rescanning or replanning is needed. The purpose of this study was to determine the effects of weight change (SSD increase or decrease) on IMRT or VMAT dose delivery in patients with prostate cancer and to determine the SSD change threshold for replanning. Whether IMRT or VMAT provides better dose stability under weight change conditions was also determined. We generated clinical IMRT and VMAT prostate and seminal vesicle treatment plans for varying SSDs for 10 randomly selected patients with prostate cancer. The differences due to SSD change were quantified by a specific dose change for a specified volume of interest. The target mean dose, decreased or increased by 2.9% per 1-cm SSD decrease or increase in IMRT and by 3.6% in VMAT. If the SSD deviation is more than 1 cm, the radiation oncology team should determine whether to continue treatment without modifications, to adjust monitor units, or to resimulate and replan.

  8. Novel Adaptive Decision Threshold Modulation Technique for UWB Direct Chaotic Communications

    Directory of Open Access Journals (Sweden)

    Said Sadoudi

    2014-11-01

    Full Text Available A new non-coherent chaotic modulation technique based on adaptive decision threshold is proposed for the UltraWideBand (UWB Direct Chaotic Communication (DCC technology. The principal advantages of the proposed technique are: (1 Removing the threshold problem of the classical Chaotic On-Off Keying modulation technique which uses a nonzero decision threshold; (2 Providing a high throughput comparing to the others techniques since it do not uses any delay at the modulation; (3 Reducing the transmitted power, thanks to a transmitted bit energy devised by two. The obtained simulation results show high Bit Error Rate performances of the proposed technique applied in an UWB DCC system. In addition, the new chaotic modulation is more suitable in all DCC-based communications schemes.

  9. SEMiX and SKYPER an Intelligent IGBT Module with Adaptable Driver

    Institute of Scientific and Technical Information of China (English)

    MartinFreyberg; MarkusHermwille; Uk-SongHong; JensLi

    2004-01-01

    Modern power converter designs need compact IGBT modules with simple interfaces for costefficient power solutions.Low overall height.separate AC and DC terminals on eaeh side,driver access on top are recent market requirements for modern power nmdules.This leads to the birth of SEMiX-a module platform with the right answer to these requirements.Moreover.this paper highlights also a new driver solution for modules-SKYPER-a simple add-on gate driver with basic driving and protection funetions.Its adaptation to modules-in this article through an example with SEMiX-is tested suecessfully.SEMiX and SKYPER behave like an IPM but offer more flexibilitv to control switching characteristics.presenting a convenient building block for modular inverter solutions.

  10. POPULATION MEAN ESTIMATE FOR ADAPTIVE MODULATION UNDER LARGE PHASE ERROR IN SINGLE BEAMFORMING SENSOR ARRAY

    Directory of Open Access Journals (Sweden)

    G. Vaikundam

    2015-04-01

    Full Text Available Beamforming is a signal processing technique to focus the transmitted energy so that maximum energy is radiated in the intended destination and communication range is enhanced. Data rate improvement in Transmit beamforming can be achieved with adaptive modulation. Though modulation adaptation is possible under zero-mean phase error, it is difficult to adapt it under non-zero mean Gaussian distributed phase error conditions. Phase errors occur due to channel estimation inaccuracies, delay in estimation, sensor drift, quantized feedback etc resulting in increased outage probability and Bit error rate. Preprocessing of beamforming weights adjusted by Sample Mean Estimate (SME solves the problem of adaptive modulation. However, under large phase error variation, the SME method fails. Hence, in this paper, Population Mean Estimate (PME approach is proposed to resolve these drawbacks for a Rayleigh flat fading channel with White Gaussian Noise. To correct the population mean error if any, Least Mean Square correction algorithm is proposed and is tested up to 80% error in PME and the corrected error fall within 10% error. Simulation results for a distributed beamforming sensor array indicate that the proposed method performs better than the SME based existing methods under worst-case phase error distribution.

  11. An intestinal microRNA modulates the homeostatic adaptation to chronic oxidative stress in C. elegans

    Science.gov (United States)

    Kato, Masaomi; Kashem, Mohammed Abul; Cheng, Chao

    2016-01-01

    Adaptation to an environmental or metabolic perturbation is a feature of the evolutionary process. Recent insights into microRNA function suggest that microRNAs serve as key players in a robust adaptive response against stress in animals through their capacity to fine-tune gene expression. However, it remains largely unclear how a microRNA-modulated downstream mechanism contributes to the process of homeostatic adaptation. Here we show that loss of an intestinally expressed microRNA gene, mir-60, in the nematode C. elegans promotes an adaptive response to chronic – a mild and long-term – oxidative stress exposure. The pathway involved appears to be unique since the canonical stress-responsive factors, such as DAF-16/FOXO, are dispensable for mir-60 loss to enhance oxidative stress resistance. Gene expression profiles revealed that genes encoding lysosomal proteases and those involved in xenobiotic metabolism and pathogen defense responses are up-regulated by the loss of mir-60. Detailed genetic studies and computational microRNA target prediction suggest that endocytosis components and a bZip transcription factor gene zip-10, which functions in innate immune response, are directly modulated by miR-60 in the intestine. Our findings suggest that the mir-60 loss facilitates adaptive response against chronic oxidative stress by ensuring the maintenance of cellular homeostasis. PMID:27623524

  12. Multiuser Diversity with Adaptive Modulation in Non-Identically Distributed Nakagami Fading Environments

    KAUST Repository

    Rao, Anlei

    2012-09-08

    In this paper, we analyze the performance of adaptive modulation with single-cell multiuser scheduling over independent but not identical distributed (i.n.i.d.) Nakagami fading channels. Closed-form expressions are derived for the average channel capacity, spectral efficiency, and bit-error-rate (BER) for both constant-power variable-rate and variable-power variable-rate uncoded/coded M-ary quadrature amplitude modulation (M-QAM) schemes. We also study the impact of time delay on the average BER of adaptive M-QAM. Selected numerical results show that the multiuser diversity brings a considerably better performance even over i.n.i.d. fading environments.

  13. Adaptive Modulation with Best User Selection over Non-Identical Nakagami Fading Channels

    KAUST Repository

    Rao, Anlei

    2012-09-08

    In this paper, we analyze the performance of adaptive modulation with single-cell multiuser scheduling over independent but not identical distributed (i.n.i.d.) Nakagami fading channels. Closed-form expressions are derived for the average channel capacity, spectral efficiency, and bit-error-rate (BER) for both constant-power variable-rate and variable-power variable-rate uncoded M-ary quadrature amplitude modulation (M-QAM) schemes. We also study the impact of time delay on the average BER of adaptive M-QAM. Selected numerical results show that the multiuser diversity brings a considerably better performance even over i.n.i.d. fading environments.

  14. A gain-of-function mutant p53–HSF1 feed forward circuit governs adaptation of cancer cells to proteotoxic stress

    OpenAIRE

    D. Li(Hunan University, Changsha 410082, People's Republic of China); Yallowitz, A; Ozog, L; Marchenko, N

    2014-01-01

    To overcome proteotoxic stress inherent to malignant transformation, cancer cells induce a range of adaptive mechanisms, with the master transcription factor heat-shock factor 1 (HSF1)-orchestrated response taking center stage. Here we define a novel gain-of-function of mutant p53 (mutp53), whereby mutp53-overexpressing cancer cells acquire superior tolerance to proteotoxic stress. mutp53 via constitutive stimulation of EGFR and ErbB2 signaling hyperactivates the MAPK and PI3K cascades, which...

  15. Adaptive Modulation for DFIG and STATCOM With High-Voltage Direct Current Transmission.

    Science.gov (United States)

    Tang, Yufei; He, Haibo; Ni, Zhen; Wen, Jinyu; Huang, Tingwen

    2016-08-01

    This paper develops an adaptive modulation approach for power system control based on the approximate/adaptive dynamic programming method, namely, the goal representation heuristic dynamic programming (GrHDP). In particular, we focus on the fault recovery problem of a doubly fed induction generator (DFIG)-based wind farm and a static synchronous compensator (STATCOM) with high-voltage direct current (HVDC) transmission. In this design, the online GrHDP-based controller provides three adaptive supplementary control signals to the DFIG controller, STATCOM controller, and HVDC rectifier controller, respectively. The mechanism is to observe the system states and their derivatives and then provides supplementary control to the plant according to the utility function. With the GrHDP design, the controller can adaptively develop an internal goal representation signal according to the observed power system states, therefore, to achieve more effective learning and modulating. Our control approach is validated on a wind power integrated benchmark system with two areas connected by HVDC transmission lines. Compared with the classical direct HDP and proportional integral control, our GrHDP approach demonstrates the improved transient stability under system faults. Moreover, experiments under different system operating conditions with signal transmission delays are also carried out to further verify the effectiveness and robustness of the proposed approach. PMID:26701900

  16. Spectral Efficiency Optimization for an Interfering Cognitive Radio with Adaptive Modulation and Coding

    CERN Document Server

    Taki, Mehrdad

    2009-01-01

    In this paper, we consider a primary and a cognitive user transmitting over a wireless fading interference channel. The primary user transmits with a constant power and utilizes an adaptive modulation and coding (AMC) scheme satisfying a bit error rate requirement. We propose a link adaptation scheme to maximize the average spectral efficiency of the cognitive radio, while a minimum required spectral efficiency for the primary user is provisioned. The resulting problem is constrained to also satisfy a bit error rate requirement and a power constraint for the cognitive link. The AMC mode selection and power control at the cognitive transmitter is optimized based on the modified signal to noise plus interference ratio feedback of both links. The problem is then cast as a nonlinear discrete optimization problem for which a fast and efficient suboptimum solution is presented. We also present a scheme with rate adaptive and constant power cognitive radio. An important characteristic of the proposed schemes is that...

  17. A microcontroller library for Arduino Wi-Fi Direct GainSpan module 1500M and the Wi-Fi Direct Android application

    OpenAIRE

    Majhen, Ivan

    2014-01-01

    Objective of the thesis is to develop microcontroller library for Arduino UNO microcontroller platform that will carry communication via serial UART interface with a wireless module GainSpan 1500M. The module supports a fairly new way of wireless communication, Wi-Fi Direct. Inclusion of library in the user microcontroller program will allow the user to set the parameters of Wi-Fi Direct connection. The library will be using user parameters to control and establish Wi-Fi Direct connection by ...

  18. A microcontroller library for Arduino Wi-Fi Direct GainSpan module 1500M and the Wi-Fi Direct Android application

    OpenAIRE

    MAJHEN, IVAN

    2015-01-01

    Objective of the thesis is to develop microcontroller library for Arduino UNO microcontroller platform that will carry communication via serial UART interface with a wireless module GainSpan 1500M. The module supports a fairly new way of wireless communication, Wi-Fi Direct. Inclusion of library in the user microcontroller program will allow the user to set the parameters of Wi-Fi Direct connection. The library will be using user parameters to control and establish Wi-Fi Direct connection by ...

  19. A local theory of effect of beam pre-modulation on gain and efficiency in a surface wave pumped free electron laser

    Science.gov (United States)

    Sharma, Jyotsna; Sharma, Suresh C.; Bhasin, Anuradha; Jain, V. K.

    2014-08-01

    A pre-modulated relativistic electron beam (REB) counter propagating to the surface wave in the vacuum region Compton backscatters the surface wave into a high frequency radiation. The surface wave extends into the vacuum region and can be employed as a wiggler for the generation of sub-millimeter waves. The growth rate and gain were evaluated for a typical FEL (Free Electron Laser) parameters and It is found that the growth rate and gain of the surface wave pumped free electron laser increases with the modulation index. Moreover, the growth rate of the FEL (Free electron Laser) instability scales as one-third power of the beam density in the Compton regime.

  20. Analysis of nonlinear optical and dynamic gain effects of moderate-power, pulse-position-modulated, erbium-doped fiber amplifiers for deep-space applications.

    Science.gov (United States)

    Yao, Haomin; Wright, Malcolm W; Marciante, John R

    2014-09-20

    Lasers for use in deep-space applications such as interplanetary optical communications employ multiwatt resonantly pumped dual-clad erbium-doped fiber amplifiers and the pulse-position modulation scheme. Nonlinear optical effects and dynamic gain effects often impair their performance and limit their operational range. These effects are analyzed theoretically and numerically with a time-dependent two-level propagation model, respectively. Self-phase modulation and stimulated Raman scattering are found to limit the usable data format space. In operational regimes free from nonlinear effects, dynamic gain effects such as the variation in the output pulse energy and square-pulse distortion are quantified. Both are found to primarily depend on the symbol duration and can be as large as 28% and 21%, respectively.

  1. All-optical OR/NOR Bi-functional logic gate by using cross-gain modulation in semiconductor optical amplifiers

    International Nuclear Information System (INIS)

    An OR/NOR bi-functional all-optical logic gate has been experimentally demonstrated at 10 Gbit/s by using cross-gain modulation (XGM) in only 2 semiconductor optical amplifiers (SOAs). One SOA was used for NOR operation and the other SOA was used for inversion to obtain OR operation. Numerical simulation has also been performed, which coincided well with the experimental results.

  2. Joint switched transmit diversity and adaptive modulation in spectrum sharing systems

    KAUST Repository

    Qaraqe, Khalid A.

    2011-01-01

    Under the scenario of an underlay cognitive radio network, we propose in this paper an adaptive scheme using switched transmit diversity and adaptive modulation in order to minimize the average number of switched branches at the secondary transmitter while increasing the capacity of the secondary link. The proposed switching efficient scheme (SES) uses the scan and wait (SWC) combining technique where a transmission occurs only when a branch with an acceptable performance is found, otherwise data is buffered. In our scheme, the modulation constellation size and the used transmit branch are determined to achieve the highest spectral efficiency with a minimum processing power, given the fading channel conditions, the required error rate performance, and a peak interference constraint to the primary receiver. Selected numerical examples show that the SES scheme minimizes the average number of switched branches for the average and the high secondary signal-to-noise ratio range. This improvement comes at the expense of a small delay introduced by the SWC technique. For reference, we also compare the performance of the SES scheme to the selection diversity scheme (SDS) where the best branch verifying the modulation mode and the interference constraint is always selected. © 2011 ICST.

  3. Modulation of extracellular matrix genes reflects the magnitude of physiological adaptation to aerobic exercise training in humans

    Directory of Open Access Journals (Sweden)

    Greenhaff Paul L

    2005-09-01

    Full Text Available Abstract Background Regular exercise reduces cardiovascular and metabolic disease partly through improved aerobic fitness. The determinants of exercise-induced gains in aerobic fitness in humans are not known. We have demonstrated that over 500 genes are activated in response to endurance-exercise training, including modulation of muscle extracellular matrix (ECM genes. Real-time quantitative PCR, which is essential for the characterization of lower abundance genes, was used to examine 15 ECM genes potentially relevant for endurance-exercise adaptation. Twenty-four sedentary male subjects undertook six weeks of high-intensity aerobic cycle training with muscle biopsies being obtained both before and 24 h after training. Subjects were ranked based on improvement in aerobic fitness, and two cohorts were formed (n = 8 per group: the high-responder group (HRG; peak rate of oxygen consumption increased by +0.71 ± 0.1 L min-1; p -1, ns. ECM genes profiled included the angiopoietin 1 and related genes (angiopoietin 2, tyrosine kinase with immunoglobulin-like and EGF-like domains 1 (TIE1 and 2 (TIE2, vascular endothelial growth factor (VEGF and related receptors (VEGF receptor 1, VEGF receptor 2 and neuropilin-1, thrombospondin-4, α2-macroglobulin and transforming growth factor β2. Results neuropilin-1 (800%; p VEGF receptor 2 (300%; p VEGF receptor 1 mRNA actually declined in the LRG (p TIE1 and TIE2 mRNA levels were unaltered in the LRG, whereas transcription levels of both genes were increased by 2.5-fold in the HRG (p thrombospondin-4 (900%; p α2-macroglobulin (300%, p transforming growth factor β2 transcript increased only in the HRG (330%; p Conclusion We demonstrate for the first time that aerobic training activates angiopoietin 1 and TIE2 genes in human muscle, but only when aerobic capacity adapts to exercise-training. The fourfold-greater increase in aerobic fitness and markedly differing gene expression profile in the HRG indicates that

  4. A 0.04 mm (2) Buck-Boost DC-DC Converter for Biomedical Implants Using Adaptive Gain and Discrete Frequency Scaling Control.

    Science.gov (United States)

    George, Libin; Gargiulo, Gaetano Dario; Lehmann, Torsten; Hamilton, Tara Julia

    2016-06-01

    This paper presents the design of a reconfigurable buck-boost switched-capacitor DC-DC converter suitable for use in a wide range of biomedical implants. The proposed converter has an extremely small footprint and uses a novel control method that allows coarse and fine control of the output voltage. The converter uses adaptive gain control, discrete frequency scaling and pulse-skipping schemes to regulate the power delivered to a range of output voltages and loads. Adaptive gain control is used to implement variable switching gain ratios from a reconfigurable power stage and thereby make coarse steps in output voltage. A discrete frequency scaling controller makes discrete changes in switching frequency to vary the power delivered to the load and perform fine tuning when the output voltage is within 10% of the target output voltage. The control architecture is predominately digital and it has been implemented as part of a fully-integrated switched-capacitor converter design using a standard bulk CMOS 0.18 μm process. Measured results show that the converter has an output voltage range of 1.0 to 2.2 V, can deliver up to 7.5 mW of load power and efficiency up to 75% using an active area of only 0.04 mm (2), which is significantly smaller than that of other designs. This low-area, low-complexity reconfigurable power converter can support low-power circuits in biomedical implant applications. PMID:26600247

  5. A 0.04 mm (2) Buck-Boost DC-DC Converter for Biomedical Implants Using Adaptive Gain and Discrete Frequency Scaling Control.

    Science.gov (United States)

    George, Libin; Gargiulo, Gaetano Dario; Lehmann, Torsten; Hamilton, Tara Julia

    2016-06-01

    This paper presents the design of a reconfigurable buck-boost switched-capacitor DC-DC converter suitable for use in a wide range of biomedical implants. The proposed converter has an extremely small footprint and uses a novel control method that allows coarse and fine control of the output voltage. The converter uses adaptive gain control, discrete frequency scaling and pulse-skipping schemes to regulate the power delivered to a range of output voltages and loads. Adaptive gain control is used to implement variable switching gain ratios from a reconfigurable power stage and thereby make coarse steps in output voltage. A discrete frequency scaling controller makes discrete changes in switching frequency to vary the power delivered to the load and perform fine tuning when the output voltage is within 10% of the target output voltage. The control architecture is predominately digital and it has been implemented as part of a fully-integrated switched-capacitor converter design using a standard bulk CMOS 0.18 μm process. Measured results show that the converter has an output voltage range of 1.0 to 2.2 V, can deliver up to 7.5 mW of load power and efficiency up to 75% using an active area of only 0.04 mm (2), which is significantly smaller than that of other designs. This low-area, low-complexity reconfigurable power converter can support low-power circuits in biomedical implant applications.

  6. CRISPR/Cas and Cmr modules, mobility and evolution of adaptive immune systems

    DEFF Research Database (Denmark)

    Shah, Shiraz Ali; Garrett, Roger Antony

    2011-01-01

    CRISPR/Cas and CRISPR/Cmr immune machineries of archaea and bacteria provide an adaptive and effective defence mechanism directed specifically against viruses and plasmids. Present data suggest that both CRISPR/Cas and Cmr modules can behave like integral genetic elements. They tend to be located...... in the more variable regions of chromosomes and are displaced by genome shuffling mechanisms including transposition. CRISPR loci may be broken up and dispersed in chromosomes by transposons with the potential for creating genetic novelty. Both CRISPR/Cas and Cmr modules appear to exchange readily between...... the significant barriers imposed by their differing conjugative, transcriptional and translational mechanisms. There are parallels between the CRISPR crRNAs and eukaryal siRNAs, most notably to germ cell piRNAs which are directed, with the help of effector proteins, to silence or destroy transposons...

  7. CAPACITY BUILDING FOR CLIMATE CHANGE ADAPTATION: MODULES FOR AGRICULTURAL EXTENSION CURRICULUM DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    B.O. Ogunbameru

    2013-02-01

    Full Text Available Basically, climate change refers to any change in climate overtime, generally caused by natural variability and/or human activities. It has great devastating impact, particularly on agriculture and by extrapolation on farmers and the national economy. The frontline agricultural extension workers are expected to be among the principal stakeholders to teach farmers how to cope with climate change. Consequently, there is a need to develop appropriate teaching package for the training of the frontline agricultural extension workers, based on the myriad of adaptation strategies and practices available in the literature. This paper synthesizes the rationale for capacity building in climate change and the adaptation or coping strategies. The modules (train-the-trainer for teaching agricultural extension workers and farmers are documented in the paper.

  8. New Adaptive Method for IQ Imbalance Compensation of Quadrature Modulators in Predistortion Systems

    Directory of Open Access Journals (Sweden)

    Hassan Zareian

    2009-01-01

    Full Text Available Imperfections in quadrature modulators (QMs, such as inphase and quadrature (IQ imbalance, can severely impact the performance of power amplifier (PA linearization systems, in particular in adaptive digital predistorters (PDs. In this paper, we first analyze the effect of IQ imbalance on the performance of a memory orthogonal polynomials predistorter (MOP PD, and then we propose a new adaptive algorithm to estimate and compensate the unknown IQ imbalance in QM. Unlike previous compensation techniques, the proposed method was capable of online IQ imbalance compensation with faster convergence, and no special calibration or training signals were needed. The effectiveness of the proposed IQ imbalance compensator was validated by simulations. The results clearly show the performance of the MOP PD to be enhanced significantly by adding the proposed IQ imbalance compensator.

  9. New Adaptive Method for IQ Imbalance Compensation of Quadrature Modulators in Predistortion Systems

    Science.gov (United States)

    Zareian, Hassan; Vakili, Vahid Tabataba

    2009-12-01

    Imperfections in quadrature modulators (QMs), such as inphase and quadrature (IQ) imbalance, can severely impact the performance of power amplifier (PA) linearization systems, in particular in adaptive digital predistorters (PDs). In this paper, we first analyze the effect of IQ imbalance on the performance of a memory orthogonal polynomials predistorter (MOP PD), and then we propose a new adaptive algorithm to estimate and compensate the unknown IQ imbalance in QM. Unlike previous compensation techniques, the proposed method was capable of online IQ imbalance compensation with faster convergence, and no special calibration or training signals were needed. The effectiveness of the proposed IQ imbalance compensator was validated by simulations. The results clearly show the performance of the MOP PD to be enhanced significantly by adding the proposed IQ imbalance compensator.

  10. Feasibility of an online adaptive replanning method for cranial frameless intensity-modulated radiosurgery

    Energy Technology Data Exchange (ETDEWEB)

    Calvo, Juan Francisco, E-mail: jfcdrr@gmail.com [Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona (Spain); San José, Sol [Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona (Spain); Garrido, LLuís [Institut de Ciències del Cosmos i Departament ECM, Universitat de Barcelona, Barcelona (Spain); Puertas, Enrique; Moragues, Sandra; Pozo, Miquel [Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona (Spain); Casals, Joan, E-mail: jfcdrr@yahoo.es [Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona (Spain)

    2013-10-01

    To introduce an approach for online adaptive replanning (i.e., dose-guided radiosurgery) in frameless stereotactic radiosurgery, when a 6-dimensional (6D) robotic couch is not available in the linear accelerator (linac). Cranial radiosurgical treatments are planned in our department using intensity-modulated technique. Patients are immobilized using thermoplastic mask. A cone-beam computed tomography (CBCT) scan is acquired after the initial laser-based patient setup (CBCT{sub setup}). The online adaptive replanning procedure we propose consists of a 6D registration-based mapping of the reference plan onto actual CBCT{sub setup}, followed by a reoptimization of the beam fluences (“6D plan”) to achieve similar dosage as originally was intended, while the patient is lying in the linac couch and the original beam arrangement is kept. The goodness of the online adaptive method proposed was retrospectively analyzed for 16 patients with 35 targets treated with CBCT-based frameless intensity modulated technique. Simulation of reference plan onto actual CBCT{sub setup}, according to the 4 degrees of freedom, supported by linac couch was also generated for each case (4D plan). Target coverage (D99%) and conformity index values of 6D and 4D plans were compared with the corresponding values of the reference plans. Although the 4D-based approach does not always assure the target coverage (D99% between 72% and 103%), the proposed online adaptive method gave a perfect coverage in all cases analyzed as well as a similar conformity index value as was planned. Dose-guided radiosurgery approach is effective to assure the dose coverage and conformity of an intracranial target volume, avoiding resetting the patient inside the mask in a “trial and error” way so as to remove the pitch and roll errors when a robotic table is not available.

  11. GABAA receptor-mediated feedforward and feedback inhibition differentially modulate the gain and the neural code transformation in hippocampal CA1 pyramidal cells.

    Science.gov (United States)

    Jang, Hyun Jae; Park, Kyerl; Lee, Jaedong; Kim, Hyuncheol; Han, Kyu Hun; Kwag, Jeehyun

    2015-12-01

    Diverse variety of hippocampal interneurons exists in the CA1 area, which provides either feedforward (FF) or feedback (FB) inhibition to CA1 pyramidal cell (PC). However, how the two different inhibitory network architectures modulate the computational mode of CA1 PC is unknown. By investigating the CA3 PC rate-driven input-output function of CA1 PC using in vitro electrophysiology, in vitro-simulation of inhibitory network, and in silico computational modeling, we demonstrated for the first time that GABAA receptor-mediated FF and FB inhibition differentially modulate the gain, the spike precision, the neural code transformation and the information capacity of CA1 PC. Recruitment of FF inhibition buffered the CA1 PC spikes to theta-frequency regardless of the input frequency, abolishing the gain and making CA1 PC insensitive to its inputs. Instead, temporal variability of the CA1 PC spikes was increased, promoting the rate-to-temporal code transformation to enhance the information capacity of CA1 PC. In contrast, the recruitment of FB inhibition sub-linearly transformed the input rate to spike output rate with high gain and low spike temporal variability, promoting the rate-to-rate code transformation. These results suggest that GABAA receptor-mediated FF and FB inhibitory circuits could serve as network mechanisms for differentially modulating the gain of CA1 PC, allowing CA1 PC to switch between different computational modes using rate and temporal codes ad hoc. Such switch will allow CA1 PC to efficiently respond to spatio-temporally dynamic inputs and expand its computational capacity during different behavioral and neuromodulatory states in vivo.

  12. Age-associated weight gain, leptin, and SIRT1: a possible role for hypothalamic SIRT1 in the prevention of weight gain and aging through modulation of leptin sensitivity

    Directory of Open Access Journals (Sweden)

    Tsutomu eSasaki

    2015-07-01

    Full Text Available The hypothalamus is the principal regulator of body weight and energy balance. It modulates both energy intake and energy expenditure by sensing the energy status of the body through neural inputs from the periphery as well as direct humoral inputs. Leptin, an adipokine, is one of the humoral factors responsible for alerting the hypothalamus that enough energy is stored in the periphery. Plasma leptin levels are positively linked to adiposity; leptin suppress energy intake and stimulates energy expenditure. However, prolonged increases in plasma leptin levels due to obesity cause leptin resistance, affecting both leptin access to hypothalamic neurons and leptin signal transduction within hypothalamic neurons. Decreased sensing of peripheral energy status through leptin may lead to a positive energy balance and gradual gains in weight and adiposity, further worsening leptin resistance. Leptin resistance, increased adiposity, and weight gain are all associated with aging in both humans and animals. Central insulin resistance is associated with similar observations. Therefore, improving the action of humoral factors in the hypothalamus may prevent gradual weight gain, especially during middle age. SIRT1 is a NAD+-dependent protein deacetylase with numerous substrates, including histones, transcription factors, co-factors, and various enzymes. SIRT1 improves both leptin sensitivity and insulin sensitivity by decreasing the levels of several molecules that impair leptin and insulin signal transduction. SIRT1 and NAD+ levels decrease with age in the hypothalamus; increased hypothalamic SIRT1 levels prevent age-associated weight gain and improve leptin sensitivity in mice. Therefore, preventing the age-dependent loss of SIRT1 function in the hypothalamus could improve the action of humoral factors in the hypothalamus as well as central regulation of energy balance.

  13. Modulation of GABAergic Transmission in Development and Neurodevelopmental Disorders: Investigating Physiology and Pathology to Gain Therapeutic Perspectives

    Directory of Open Access Journals (Sweden)

    Gabriele eDeidda

    2014-05-01

    Full Text Available During mammalian ontogenesis, the neurotransmitter GABA is a fundamental regulator of neuronal networks. In neuronal development, GABAergic signaling regulates neural proliferation, migration, differentiation, and neuronal-network wiring. In the adult, GABA orchestrates the activity of different neuronal cell-types largely interconnected, by powerfully modulating synaptic activity. GABA exerts these functions by binding to chloride-permeable ionotropic GABAA receptors and metabotropic GABAB receptors. According to its functional importance during development, GABA is implicated in a number of neurodevelopmental disorders such as autism, Fragile X, Rett syndrome, Down syndrome, schizophrenia, Tourette's syndrome and neurofibromatosis.The strength and polarity of GABAergic transmission is continuously modulated during physiological, but also pathological conditions. For GABAergic transmission through GABAA receptors, strength regulation is achieved by different mechanisms such as modulation of GABAA receptors themselves, variation of intracellular chloride concentration, and alteration in GABA metabolism. In the never-ending effort to find possible treatments for GABA-related neurological diseases, of great importance would be modulating GABAergic transmission in a safe and possibly physiological way, without the dangers of either silencing network activity or causing epileptic seizures. In this review, we will discuss the different ways to modulate GABAergic transmission normally at work both during physiological and pathological conditions. Our aim is to highlight new research perspectives for therapeutic treatments that reinstate natural and physiological brain functions in neuro-pathological conditions.

  14. Evaluation of tropically adapted straightbred and crossbred cattle: postweaning gain and feed efficiency when finished in a temperate climate.

    Science.gov (United States)

    Coleman, S W; Chase, C C; Phillips, W A; Riley, D G; Olson, T A

    2012-06-01

    Beef cows in the subtropical USA must be adapted to the stressors of the environment, typically supplied by using Brahman (Br) breeding. Calves produced in the region, however, are usually grown and finished in more temperate regions, and have a perceived reputation for poor ADG and feed efficiency during finishing. Compromised fertility and carcass quality often associated with the Br have increased interest in tropically adapted Bos taurus breed types. The objective of this study was to evaluate 3 breeds [An = Angus (Bos taurus, temperate); Br (B. indicus, tropical); and Ro = Romosinuano (B. taurus, tropical)] and all possible crosses during various segments of post-weaning growth, and for feed efficiency during the finishing phase. Steer calves (n = 473) born over 3 yr were weaned in late September, backgrounded for at least 21 d (BKG), shipped 2,025 km to El Reno, OK, in October, fed a preconditioning diet for 28 d (RCV), grazed wheat (Triticum aestivum L.) pasture from November to May (WHT), finished on a conventional feedlot diet (FIN), and serially harvested after approximately 95, 125, and 150 d on feed. Body weight and ADG during each segment were tested using a mixed model that included calf age at weaning, year (Y), breed of sire (SB), breed of dam (DB), and interactions. In addition, winter treatment (continuous wheat or reduced grazing of wheat with supplement) was included for the wheat and feedlot phases. Sire within SB × SB [and pen (barn × year) for feedlot phase] were considered random. The SB × DB interaction was significant for all traits (P < 0.01) except exit velocity taken at weaning and ADG during FIN, but both traits were affected by 3-way interactions with Y or harvest group. Tropically-adapted purebred steers had greater (P < 0.01) ADG than AnAn through weaning and BKG in FL but the reverse was true during the RCV and WHT segments. Similar, but less pronounced results were noted for F(1) steers with 100% tropical influence compared

  15. Evaluation of tropically adapted straightbred and crossbred cattle: postweaning gain and feed efficiency when finished in a temperate climate.

    Science.gov (United States)

    Coleman, S W; Chase, C C; Phillips, W A; Riley, D G; Olson, T A

    2012-06-01

    Beef cows in the subtropical USA must be adapted to the stressors of the environment, typically supplied by using Brahman (Br) breeding. Calves produced in the region, however, are usually grown and finished in more temperate regions, and have a perceived reputation for poor ADG and feed efficiency during finishing. Compromised fertility and carcass quality often associated with the Br have increased interest in tropically adapted Bos taurus breed types. The objective of this study was to evaluate 3 breeds [An = Angus (Bos taurus, temperate); Br (B. indicus, tropical); and Ro = Romosinuano (B. taurus, tropical)] and all possible crosses during various segments of post-weaning growth, and for feed efficiency during the finishing phase. Steer calves (n = 473) born over 3 yr were weaned in late September, backgrounded for at least 21 d (BKG), shipped 2,025 km to El Reno, OK, in October, fed a preconditioning diet for 28 d (RCV), grazed wheat (Triticum aestivum L.) pasture from November to May (WHT), finished on a conventional feedlot diet (FIN), and serially harvested after approximately 95, 125, and 150 d on feed. Body weight and ADG during each segment were tested using a mixed model that included calf age at weaning, year (Y), breed of sire (SB), breed of dam (DB), and interactions. In addition, winter treatment (continuous wheat or reduced grazing of wheat with supplement) was included for the wheat and feedlot phases. Sire within SB × SB [and pen (barn × year) for feedlot phase] were considered random. The SB × DB interaction was significant for all traits (P < 0.01) except exit velocity taken at weaning and ADG during FIN, but both traits were affected by 3-way interactions with Y or harvest group. Tropically-adapted purebred steers had greater (P < 0.01) ADG than AnAn through weaning and BKG in FL but the reverse was true during the RCV and WHT segments. Similar, but less pronounced results were noted for F(1) steers with 100% tropical influence compared

  16. Time-domain simulation of channel crosstalk and inter-modulation distortion in gain-clamped semiconductor optical amplifiers

    Science.gov (United States)

    Li, Xun; Park, Jongwoon

    2006-07-01

    A time-domain model is implemented for gain-clamped semiconductor optical amplifiers (GC-SOAs) based on a combination of the separated traveling-wave equations and effective Bloch equations. The key feature of this model lies in its capability of handling the lasing-signal, signal-signal, and signal-noise interactions over a broad wavelength band. Therefore, various nonlinear phenomena such as the cross-gain saturation (XGS) and nondegenerate four-wave mixing (ND-FWM) can readily be captured. After being implemented and validated, this model is applied to the simulation of GC-SOA dynamic behaviors such as the channel crosstalk and intermodulation distortion (IMD). Simulation results show that the third-order IMD can be effectively suppressed by a gain-clamping lasing mode in GC-SOAs in comparison with that in conventional SOAs. The channel crosstalk can also be suppressed to some extent in GC-SOAs, but not as effectively. Other than a homogeneous reduction, the gain-clamping in GC-SOAs does not change the dependence of the channel crosstalk and IMD on the input signal power and channel spacing. It is also shown that the channel crosstalk, unlike the IMD, cannot be efficiently reduced by enlarging the channel spacing even in GC-SOAs.

  17. CSI Feedback-based CS for Underwater Acoustic Adaptive Modulation OFDM System with Channel Prediction

    Institute of Scientific and Technical Information of China (English)

    蒯小燕; 孙海信; 齐洁; 程恩; 许小卡; 郭瑜辉; 陈友淦

    2014-01-01

    In this paper, we investigate the performance of adaptive modulation (AM) orthogonal frequency division multiplexing (OFDM) system in underwater acoustic (UWA) communications. The aim is to solve the problem of large feedback overhead for channel state information (CSI) in every subcarrier. A novel CSI feedback scheme is proposed based on the theory of compressed sensing (CS). We propose a feedback from the receiver that only feedback the sparse channel parameters. Additionally, prediction of the channel state is proposed every several symbols to realize the AM in practice. We describe a linear channel prediction algorithm which is used in adaptive transmission. This system has been tested in the real underwater acoustic channel. The linear channel prediction makes the AM transmission techniques more feasible for acoustic channel communications. The simulation and experiment show that significant improvements can be obtained both in bit error rate (BER) and throughput in the AM scheme compared with the fixed Quadrature Phase Shift Keying (QPSK) modulation scheme. Moreover, the performance with standard CS outperforms the Discrete Cosine Transform (DCT) method.

  18. Adaptive software-defined coded modulation for ultra-high-speed optical transport

    Science.gov (United States)

    Djordjevic, Ivan B.; Zhang, Yequn

    2013-10-01

    In optically-routed networks, different wavelength channels carrying the traffic to different destinations can have quite different optical signal-to-noise ratios (OSNRs) and signal is differently impacted by various channel impairments. Regardless of the data destination, an optical transport system (OTS) must provide the target bit-error rate (BER) performance. To provide target BER regardless of the data destination we adjust the forward error correction (FEC) strength. Depending on the information obtained from the monitoring channels, we select the appropriate code rate matching to the OSNR range that current channel OSNR falls into. To avoid frame synchronization issues, we keep the codeword length fixed independent of the FEC code being employed. The common denominator is the employment of quasi-cyclic (QC-) LDPC codes in FEC. For high-speed implementation, low-complexity LDPC decoding algorithms are needed, and some of them will be described in this invited paper. Instead of conventional QAM based modulation schemes, we employ the signal constellations obtained by optimum signal constellation design (OSCD) algorithm. To improve the spectral efficiency, we perform the simultaneous rate adaptation and signal constellation size selection so that the product of number of bits per symbol × code rate is closest to the channel capacity. Further, we describe the advantages of using 4D signaling instead of polarization-division multiplexed (PDM) QAM, by using the 4D MAP detection, combined with LDPC coding, in a turbo equalization fashion. Finally, to solve the problems related to the limited bandwidth of information infrastructure, high energy consumption, and heterogeneity of optical networks, we describe an adaptive energy-efficient hybrid coded-modulation scheme, which in addition to amplitude, phase, and polarization state employs the spatial modes as additional basis functions for multidimensional coded-modulation.

  19. Mental fatigue modulates dynamic adaptation to perceptual demand in speeded detection.

    Directory of Open Access Journals (Sweden)

    Robert Langner

    Full Text Available When stimulus intensity in simple reaction-time tasks randomly varies across trials, detection speed usually improves after a low-intensity trial. With auditory stimuli, this improvement was often found to be asymmetric, being greater on current low-intensity trials. Our study investigated (1 whether asymmetric sequential intensity adaptation also occurs with visual stimuli; (2 whether these adjustments reflect decision-criterion shifts or, rather, a modulation of perceptual sensitivity; and (3 how sequential intensity adaptation and its underlying mechanisms are affected by mental fatigue induced through prolonged performance. In a continuous speeded detection task with randomly alternating high- and low-intensity visual stimuli, the reaction-time benefit after low-intensity trials was greater on subsequent low- than high-intensity trials. This asymmetry, however, only developed with time on task (TOT. Signal-detection analyses showed that the decision criterion transiently became more liberal after a low-intensity trial, whereas observer sensitivity increased when the preceding and current stimulus were of equal intensity. TOT-induced mental fatigue only affected sensitivity, which dropped more on low- than on high-intensity trials. This differential fatigue-related sensitivity decrease selectively enhanced the impact of criterion down-shifts on low-intensity trials, revealing how the interplay of two perceptual mechanisms and their modulation by fatigue combine to produce the observed overall pattern of asymmetric performance adjustments to varying visual intensity in continuous speeded detection. Our results have implications for similar patterns of sequential demand adaptation in other cognitive domains as well as for real-world prolonged detection performance.

  20. Dynamics of Distraction: Competition among Auditory Streams Modulates Gain and Disrupts Inter-Trial Phase Coherence in the Human Electroencephalogram

    Science.gov (United States)

    Ponjavic-Conte, Karla D.; Hambrook, Dillon A.; Pavlovic, Sebastian; Tata, Matthew S.

    2013-01-01

    Auditory distraction is a failure to maintain focus on a stream of sounds. We investigated the neural correlates of distraction in a selective-listening pitch-discrimination task with high (competing speech) or low (white noise) distraction. High-distraction impaired performance and reduced the N1 peak of the auditory Event-Related Potential evoked by probe tones. In a series of simulations, we explored two theories to account for this effect: disruption of sensory gain or a disruption of inter-trial phase consistency. When compared to these simulations, our data were consistent with both effects of distraction. Distraction reduced the gain of the auditory evoked potential and disrupted the inter-trial phase consistency with which the brain responds to stimulus events. Tones at a non-target, unattended frequency were more susceptible to the effects of distraction than tones within an attended frequency band. PMID:23326548

  1. Dynamics of distraction: competition among auditory streams modulates gain and disrupts inter-trial phase coherence in the human electroencephalogram.

    Directory of Open Access Journals (Sweden)

    Karla D Ponjavic-Conte

    Full Text Available Auditory distraction is a failure to maintain focus on a stream of sounds. We investigated the neural correlates of distraction in a selective-listening pitch-discrimination task with high (competing speech or low (white noise distraction. High-distraction impaired performance and reduced the N1 peak of the auditory Event-Related Potential evoked by probe tones. In a series of simulations, we explored two theories to account for this effect: disruption of sensory gain or a disruption of inter-trial phase consistency. When compared to these simulations, our data were consistent with both effects of distraction. Distraction reduced the gain of the auditory evoked potential and disrupted the inter-trial phase consistency with which the brain responds to stimulus events. Tones at a non-target, unattended frequency were more susceptible to the effects of distraction than tones within an attended frequency band.

  2. Cultural adaptation and validation of the Freiburg Life Quality Assessment - Wound Module to Brazilian Portuguese

    Directory of Open Access Journals (Sweden)

    Elaine Aparecida Rocha Domingues

    2016-01-01

    Full Text Available Objectives: to adapt the Freiburg Life Quality Assessment - Wound Module to Brazilian Portuguese and to measure its psychometric properties: reliability and validity. Method: the cultural adaptation was undertaken following the stages of translation, synthesis of the translations, back translation, committee of specialists, pre-test and focus group. A total of 200 patients participated in the study. These were recruited in Primary Care Centers, Family Health Strategy Centers, in a philanthropic hospital and in a teaching hospital. Reliability was assessed through internal consistency and stability. Validity was ascertained through the correlation of the instrument's values with those of the domains of the Ferrans and Powers Quality of Life Index - Wound Version and with the quality of life score of the visual analog scale. Results: the instrument presented adequate internal consistency (Cronbach alpha =0.86 and high stability in the test and retest (0.93. The validity presented correlations of moderate and significant magnitude (-0.24 to -0.48, p<0.0001. Conclusion: the results indicated that the adapted version presented reliable and valid psychometric measurements for the population with chronic wounds in the Brazilian culture.

  3. Cultural adaptation and validation of the Freiburg Life Quality Assessment - Wound Module to Brazilian Portuguese1

    Science.gov (United States)

    Domingues, Elaine Aparecida Rocha; Alexandre, Neusa Maria Costa; da Silva, José Vitor

    2016-01-01

    Objectives: to adapt the Freiburg Life Quality Assessment - Wound Module to Brazilian Portuguese and to measure its psychometric properties: reliability and validity. Method: the cultural adaptation was undertaken following the stages of translation, synthesis of the translations, back translation, committee of specialists, pre-test and focus group. A total of 200 patients participated in the study. These were recruited in Primary Care Centers, Family Health Strategy Centers, in a philanthropic hospital and in a teaching hospital. Reliability was assessed through internal consistency and stability. Validity was ascertained through the correlation of the instrument's values with those of the domains of the Ferrans and Powers Quality of Life Index - Wound Version and with the quality of life score of the visual analog scale. Results: the instrument presented adequate internal consistency (Cronbach alpha =0.86) and high stability in the test and retest (0.93). The validity presented correlations of moderate and significant magnitude (-0.24 to -0.48, p<0.0001). Conclusion: the results indicated that the adapted version presented reliable and valid psychometric measurements for the population with chronic wounds in the Brazilian culture. PMID:27143539

  4. Adaptive control based on fast online algebraic identification and GPI control for magnetic levitation systems with time-varying input gain

    Science.gov (United States)

    Morales, R.; Sira-Ramírez, H.; Feliu, V.

    2014-08-01

    This paper considers the position tracking problem of a voltage-controlled magnetic levitation system (MLS) in the presence of modelling errors caused by uncertainties in the system's physical parameters. An adaptive control based on fast online algebraic parameter estimation and generalised proportional integral (GPI) output feedback control is considered as a control scheme candidate. The GPI controller guarantees an asymptotically exponentially stable behaviour of the controlled ball position and the possibilities of carrying out rest-to-rest trajectory tracking tasks. The nature of the control input gain in an MLS is that of a state-dependent time-varying gain, reflecting the nonlinear character of the magnetic force with regard to the distance and the properties of the metallic ball. The system gain has therefore been locally approximated using a periodically updated time polynomial function (of second degree), where the coefficients of the polynomial are estimated during a very short period of time. This estimation is achieved using the recently introduced algebraic online parameter estimation approach. The stability of the closed-loop system is demonstrated under the assumption that no external factors cause changes in the parameter during the time interval in which the stability is analysed. Finally, experimental results are presented for the controlled MLS demonstrating the excellent stabilisation and position tracking performance of the control system designed in the presence of significant nonlinearities and uncertainties of the underlying system.

  5. Adaptable Web Modules to Stimulate Active Learning in Engineering Hydrology using Data and Model Simulations of Three Regional Hydrologic Systems

    Science.gov (United States)

    Habib, E. H.; Tarboton, D. G.; Lall, U.; Bodin, M.; Rahill-Marier, B.; Chimmula, S.; Meselhe, E. A.; Ali, A.; Williams, D.; Ma, Y.

    2013-12-01

    server-based system. Open source web technologies and community-based tools are used to facilitate wide dissemination and adaptation by diverse, independent institutions. The new hydrologic learning modules are based on recent developments in hydrologic modeling, data, and resources. The modules are embedded in three regional-scale ecosystems, Coastal Louisiana, Florida Everglades, and Utah Great Salt Lake Basin. These sites provide a wealth of hydrologic concepts and scenarios that can be used in most water resource and hydrology curricula. The study develops several learning modules based on the three hydro-systems covering subjects such as: water-budget analysis, effects of human and natural changes, climate-hydrology teleconnections, and water-resource management scenarios. The new developments include an instructional interface to give critical guidance and support to the learner and an instructor's guide containing adaptation and implementation procedures to assist instructors in adopting and integrating the material into courses and provide a consistent experience. The design of the new hydrologic education developments will be transferable to independent institutions and adaptable both instructionally and technically through a server system capable of supporting additional developments by the educational community.

  6. Reduction of patterning effects in SOA-based wavelength converters by combining cross-gain and cross-absorption modulation

    DEFF Research Database (Denmark)

    Zhou, Enbo; Öhman, Filip; Cheng, Cheng;

    2008-01-01

    A scheme for mitigating patterning effects in wavelength conversion by using a concatenated semiconductor optical amplifier (SOA) and electroabsorption modulator (EAM) is proposed. The optimization of the parameters of the semiconductor devices and receiver electronics is theoretically investigated....... The bit error ration (BER) of the output signals in both the co-propagating and the counter-propagating configurations is quantitatively evaluated. The simulation results indicate that the patterning effect in wavelength conversion due to the slow recovery of the carrier density in the SOA can be well...

  7. Adaptive electron beam shaping using a photoemission gun and spatial light modulator

    Science.gov (United States)

    Maxson, Jared; Lee, Hyeri; Bartnik, Adam C.; Kiefer, Jacob; Bazarov, Ivan

    2015-02-01

    The need for precisely defined beam shapes in photoelectron sources has been well established. In this paper, we use a spatial light modulator and simple shaping algorithm to create arbitrary, detailed transverse laser shapes with high fidelity. We transmit this shaped laser to the photocathode of a high voltage dc gun. Using beam currents where space charge is negligible, and using an imaging solenoid and fluorescent viewscreen, we show that the resultant beam shape preserves these detailed features with similar fidelity. Next, instead of transmitting a shaped laser profile, we use an active feedback on the unshaped electron beam image to create equally accurate and detailed shapes. We demonstrate that this electron beam feedback has the added advantage of correcting for electron optical aberrations, yielding shapes without skew. The method may serve to provide precisely defined electron beams for low current target experiments, space-charge dominated beam commissioning, as well as for online adaptive correction of photocathode quantum efficiency degradation.

  8. PERFORMANCE EVALUATION OF ADAPTIVE LDPC CODED MODULATION COOPERATIVE WIRELESS COMMUNICATION SYSTEM WITH BEST-RELAY SELECTION

    Directory of Open Access Journals (Sweden)

    Ahmed S. Mohamed

    2014-03-01

    Full Text Available In this paper the performance of a cooperative wireless communication system based on combined best relay selection (BRS and adaptive LDPC coded modulation (ACM scheme is investigated. These investigations are focused on evaluating the performance of the proposed cooperative wireless communication system over independent non-identical Rayleigh fading channels in terms of bit-error rate (BER using MATLAB® computer simulations and comparing the system performance with ACM direct transmission and ACM cooperative with single relay. The simulations results show that the proposed cooperative scheme achieves lower signal-to-noise ratio (SNR values for desired bit-error rate (BER and high spectral efficiency as compared to ACM direct transmission and ACM cooperative with single relay.

  9. Functional analysis of neurovascular adaptations to exercise in the dentate gyrus of young adult mice associated with cognitive gain.

    Science.gov (United States)

    Clark, Peter J; Brzezinska, Weronika J; Puchalski, Emily K; Krone, David A; Rhodes, Justin S

    2009-10-01

    The discovery that aerobic exercise increases adult hippocampal neurogenesis and can enhance cognitive performance holds promise as a model for regenerative medicine. This study adds two new pieces of information to the rapidly growing field. First, we tested whether exercise increases vascular density in the granular layer of the dentate gyrus, whole hippocampus, and striatum in C57BL/6J mice known to display procognitive effects of exercise. Second, we determined the extent to which new neurons from exercise participate in the acute neuronal response to high levels of running in B6D2F1/J (F1 hybrid of C57BL/6J female by DBA/2J male). Mice were housed with or without a running wheel for 50 days (runner vs. sedentary). The first 10 days, they received daily injections of BrdU to label dividing cells. The last 10 days, mice were tested for performance on the Morris water maze and rotarod and then euthanized to measure neurogenesis, c-Fos induction from running and vascular density. In C57BL/6J, exercise increased neurogenesis, density of blood vessels in the dentate gyrus and striatum (but not whole hippocampus), and enhanced performance on the water maze and rotarod. In B6D2F1/J, exercise also increased hippocampal neurogenesis but not vascular density in the granular layer. Improvement on the water maze from exercise was marginal, and no gain was seen for rotarod, possibly because of a ceiling effect. Running increased the number of c-Fos positive neurons in the granular layer by fivefold, and level of running was strongly correlated with c-Fos within 90 min before euthanasia. In runners, approximately 3.3% (+/-0.008 S.E.) of BrdU-positive neurons in the middle of the granule layer displayed c-Fos when compared with 0.8% (+/-0.001) of BrdU-negative neurons. Results suggest that procognitive effects of exercise are associated with increased vascular density in the dentate gyrus and striatum in C57BL/6J mice, and that new neurons from exercise preferentially

  10. Adaptive Physiological Response to Perceived Scarcity as a Mechanism of Sensory Modulation of Life Span.

    Science.gov (United States)

    Waterson, Michael J; Chan, Tammy P; Pletcher, Scott D

    2015-09-01

    Chemosensation is a potent modulator of organismal physiology and longevity. In Drosophila, loss of recognition of diverse tastants has significant and bidirectional life-span effects. Recently published results revealed that when flies were unable to taste water, they increased its internal generation, which may have subsequently altered life span. To determine whether similar adaptive responses occur in other contexts, we explored the impact of sensory deficiency of other metabolically important molecules. Trehalose is a major circulating carbohydrate in the fly that is recognized by the gustatory receptor Gr5a. Gr5a mutant flies are short lived, and we found that they specifically increased whole-body and circulating levels of trehalose, but not other carbohydrates, likely through upregulation of de novo synthesis. dILP2 transcript levels were increased in Gr5a mutants, a possible response intended to reduce hypertrehalosemia, and likely a contributing factor to their reduced life span. Together, these data suggest that compensatory physiological responses to perceived environmental scarcity, which are designed to alleviate the ostensive shortage, may be a common outcome of sensory manipulation. We suggest that future investigations into the mechanisms underlying sensory modulation of aging may benefit by focusing on direct or indirect consequences of physiological changes that are designed to correct perceived disparity with the environment. PMID:25878032

  11. Cross-layer combining of adaptive modulation and truncated ARQ under cognitive radio resource requirements

    KAUST Repository

    Yang, Yuli

    2012-11-01

    In addressing the issue of taking full advantage of the shared spectrum under imposed limitations in a cognitive radio (CR) network, we exploit a cross-layer design for the communications of secondary users (SUs), which combines adaptive modulation and coding (AMC) at the physical layer with truncated automatic repeat request (ARQ) protocol at the data link layer. To achieve high spectral efficiency (SE) while maintaining a target packet loss probability (PLP), switching among different transmission modes is performed to match the time-varying propagation conditions pertaining to the secondary link. Herein, by minimizing the SU\\'s packet error rate (PER) with each transmission mode subject to the spectrum-sharing constraints, we obtain the optimal power allocation at the secondary transmitter (ST) and then derive the probability density function (pdf) of the received SNR at the secondary receiver (SR). Based on these statistics, the SU\\'s packet loss rate and average SE are obtained in closed form, considering transmissions over block-fading channels with different distributions. Our results quantify the relation between the performance of a secondary link exploiting the cross-layer-designed adaptive transmission and the interference inflicted on the primary user (PU) in CR networks. © 1967-2012 IEEE.

  12. Adaptive neuro-fuzzy prediction of modulation transfer function of optical lens system

    Science.gov (United States)

    Petković, Dalibor; Shamshirband, Shahaboddin; Anuar, Nor Badrul; Md Nasir, Mohd Hairul Nizam; Pavlović, Nenad T.; Akib, Shatirah

    2014-07-01

    The quantitative assessment of image quality is an important consideration in any type of imaging system. The modulation transfer function (MTF) is a graphical description of the sharpness and contrast of an imaging system or of its individual components. The MTF is also known and spatial frequency response. The MTF curve has different meanings according to the corresponding frequency. The MTF of an optical system specifies the contrast transmitted by the system as a function of image size, and is determined by the inherent optical properties of the system. In this study, the adaptive neuro-fuzzy (ANFIS) estimator is designed and adapted to predict MTF value of the actual optical system. Neural network in ANFIS adjusts parameters of membership function in the fuzzy logic of the fuzzy inference system. The back propagation learning algorithm is used for training this network. This intelligent estimator is implemented using MATLAB/Simulink and the performances are investigated. The simulation results presented in this paper show the effectiveness of the developed method.

  13. Modulation transfer function estimation of optical lens system by adaptive neuro-fuzzy methodology

    Science.gov (United States)

    Petković, Dalibor; Shamshirband, Shahaboddin; Pavlović, Nenad T.; Anuar, Nor Badrul; Kiah, Miss Laiha Mat

    2014-07-01

    The quantitative assessment of image quality is an important consideration in any type of imaging system. The modulation transfer function (MTF) is a graphical description of the sharpness and contrast of an imaging system or of its individual components. The MTF is also known and spatial frequency response. The MTF curve has different meanings according to the corresponding frequency. The MTF of an optical system specifies the contrast transmitted by the system as a function of image size, and is determined by the inherent optical properties of the system. In this study, the adaptive neuro-fuzzy (ANFIS) estimator is designed and adapted to estimate MTF value of the actual optical system. Neural network in ANFIS adjusts parameters of membership function in the fuzzy logic of the fuzzy inference system. The back propagation learning algorithm is used for training this network. This intelligent estimator is implemented using Matlab/Simulink and the performances are investigated. The simulation results presented in this paper show the effectiveness of the developed method.

  14. Challenges for the Adaptive Gain Integrating Pixel Detector (AGIPD) design due to the high intensity photon radiation environment at the European XFEL

    CERN Document Server

    Becker, J; Göttlicher, P; Graafsma, H; Hirsemann, H; Jack, S; Klyuev, A; Marras, S Lange A; Trunk, U; Klanner, R; Schwandt, J; Zhang, J; Dinapoli, R; Greiffenberg, D; Henrich, B; Mozzanica, A; Schmitt, B; Shi, X; Gronewald, M; Krüger, H

    2013-01-01

    The European X-ray Free Electron Laser (XFEL) is a new research facility currently under construction in Hamburg, Germany. With a pulse length of less than 100 fs and an extremely high luminosity of 27000 flashes per second the European XFEL will have a unique time structure that demands the development of new detectors tailored to the requirements imposed by the experiments while complying with the machine specific operation parameters. The Adaptive Gain Integrating Pixel Detector (AGIPD) is one response to the need for large 2D detectors, able to cope with the 4.5 MHz frame rate, as well as with the high dynamic range needed by XFEL experiments ranging from single photons to more than 10$^4$ 12 keV photons per pixel per pulse. In addition it has to withstand doses of up to 1 GGy over three years.

  15. A Better Affine Projection Algorithm (APA) Using Adaptive Gain (AG)%自适应增益APA-AG算法的研究

    Institute of Scientific and Technical Information of China (English)

    智永锋; 范蟠果; 张骏; 邓正宏; 张怡

    2011-01-01

    为了提高自适应滤波器的收敛性和跟踪性,提出了一种自适应增益APA-AG算法.通过分析估计输出误差信号,获得了参数迭代步长的一个特定值估计,以实现集平均代价函数最小化.仿真结果表明,相比较于传统的APA算法,文中研究的APA-AG算法具有更快的收敛速率和更好的跟踪特性.%Aim. To improve the convergence rate and tracking performance of an adaptive filter, especially for the highly colored input signals, Refs. 3 and 4 adopt the APA algorithm. However, its gain does not change, and thus its convergence is not as rapid as is possible, in our opinion, with adaptive gain. We explain mathematically in sections 1, 2 and 3 of the full paper our APA-AG algorithm and discuss how to minimize the ensemble-average cost function by analyzing the estimated output-error. The core of section 2, which is entitled the estimated output-error analysis of the APA algorithm, is that we derive eq. (23). The core of section 3, which is entitled APA-AG algorithm, is that, to minimize the ensemble-average cost function, we obtain the estimated iterated step-sizes of our APA-AG algorithm; the needed equations are eqs. (23), (3c), (28), (27), (26) and (30). Section 4 presents two numerical examples to simulate our APA-AG algorithm; the simulation results, shown in Figs. 1 and 2,and their analysis indicate preliminarily that our APA-AG algorithm has faster convergence rate and better tracking performance compared with the conventional APA algorithm.

  16. 基于信息增益的自适应主题爬行策略%Adaptive focused crawling method based on information gain

    Institute of Scientific and Technical Information of China (English)

    熊忠阳; 史艳; 张玉芳

    2012-01-01

    结合信息增益,提出了一种新的自适应主题爬行策略.利用维基百科的分类树和主题描述文档构建主题向量7,并在爬行过程中不断地进行自动学习,反馈更新主题向量空间中每个概念的权重,完善主题描述.实验结果表明,该方法具有增量爬行的能力,并在信息量总和上明显优于基于the interest ratio的自适应策略;且前者所爬取的网页更接近于与主题相关.%In combination with information gain, this paper proposed a new adaptive focused crawling method. It set up topic vector T by category tree and topic descriptive article of Wikipedia, and automatically learned and fed back to modify weight of each concept in the topic vector space during crawling, improving topic description. Experimental results show that the method contributes to the focused crawler an incremental crawling ability, it is superior to the adaptive method based on the interest ratio significantly in terms of sum of information, and Web pages crawled with the former are more related to the topic than the latter.

  17. An adapted modulation transfer function for x-ray backscatter radiography by selective detection

    Science.gov (United States)

    Sabri, Nissia; Dugan, Edward T.; Jacobs, Alan M.; Shedlock, Daniel

    2007-09-01

    The Modulation Transfer Function (MTF) is a quantitative function based on frequency resolution that characterizes imaging system performance. In this study, a new MTF methodology is investigated for application to Radiography by Selective Detection (RSD), an enhanced single-side x-ray Compton backscatter imaging (CBI) technique which detects selected scatter components. The RSD imaging modality is a unique type of real-time radiography that uses a set of fin and sleeve collimators to preferentially select different components of the x-ray backscattered field. Radiography by selective detection has performed successfully in different non-destructive evaluation (NDE) applications. A customized RSD imaging system was built at the University of Florida for inspection of the space shuttle external tank spray-on foam insulation (SOFI). The x-ray backscatter RSD imaging system has been successfully used for crack and corrosion detection in a variety of materials. The conventional transmission x-ray image quality characterization tools do not apply for RSD because of the different physical process involved. Thus, the main objective of this project is to provide an adapted tool for dynamic evaluation of RSD system image quality. For this purpose, an analytical model of the RSD imaging system response is developed and supported. Two approaches are taken for the MTF calculations: one using the Fourier Transform of a line spread function and the other one using a sine function pattern. Calibration and test targets are then designed according to this proposed model. A customized Matlab code using image contrast and digital curve recognition is developed to support the experimental data and provide the Modulation Transfer Functions for RSD.

  18. New Crystalline Materials for Nonlinear Frequency Conversion, Electro-Optic Modulation, and Mid-Infrared Gain Media

    Energy Technology Data Exchange (ETDEWEB)

    Adams, J

    2002-08-09

    New crystalline materials were investigated for applications in frequency conversion of near-infrared wavelengths and as gain media for tunable mid-infrared solid-state lasers. GaCa{sub 4}O(BO{sub 3}){sub 3} (GdCOB), YCa{sub 4}O(BO{sub 3}){sub 3} (YCOB), LaCa{sub 4}O(BO{sub 3}){sub 3} (LaCOB), and Gd{sub 0.275}Y{sub 0.725}Ca{sub 4}O(BO{sub 3}){sub 3} were characterized for frequency conversion of 1 {micro}m lasers. For type I doubling at 1064 nm, LaCOB, GdCOB, and YCOB were found to have effective coupling coefficients (d{sub eff}) of 0.52 {+-} 0.05, 0.78 {+-} 0.06, and 1.12 {+-} 0.07 pm/V, respectively. LaCOB was measured to have angular and thermal sensitivities of 1224 {+-} 184 (cm-rad){sup -1} and < 0.10 (cm-{sup o}C){sup -1}, respectively. The effective coupling coefficient for type II noncritically phasematched (NCPM) doubling at 1064 nm in Gd{sub 0.275}Y{sub 0.725}Ca{sub 4}O(BO{sub 3}){sub 3} was measured to be 0.37 {+-} 0.04 pm/V. We predict LaCOB to have a type I NCPM fundamental wavelength of 1042 {+-} 1.5 nm. Due to its low angular and thermal sensitivities for doubling near 1047 nm, LaCOB has potential for frequency doubling of high-average power Nd:LiYF{sub 4} and Yb:Sr{sub 5}(P0{sub 4}){sub 3}F lasers. LaCOB, GdCOB, and YCOB were also investigated for optical parametric oscillator applications and we determined that they may have potential in a Ti:sapphire pumped oscillator. The effective linear electro-optic coefficients (r{sub eff}) were measured along dielectric directions in YCOB and a maximum r{sub eff} of 10.8 pm/V was found. For a crystal with a 5:1 aspect ratio, the corresponding half-wave voltage at 1064 nm would be 19.6 kV. Therefore a Pockels cell composed of two YCOB crystals with 5:1 aspect ratios would have a required half-wave voltage <10 kV. Moderate coupling coefficients (3 x KH{sub 2}PO{sub 4}), low thermal sensitivities, ease of growth to large sizes, non-hygroscopicity, and favorable polishing and coating characteristics make La

  19. Adaptation Independent Modulation of Auditory Hair Cell Mechanotransduction Channel Open Probability Implicates a Role for the Lipid Bilayer.

    Science.gov (United States)

    Peng, Anthony W; Gnanasambandam, Radhakrishnan; Sachs, Frederick; Ricci, Anthony J

    2016-03-01

    The auditory system is able to detect movement down to atomic dimensions. This sensitivity comes in part from mechanisms associated with gating of hair cell mechanoelectric transduction (MET) channels. MET channels, located at the tops of stereocilia, are poised to detect tension induced by hair bundle deflection. Hair bundle deflection generates a force by pulling on tip-link proteins connecting adjacent stereocilia. The resting open probability (P(open)) of MET channels determines the linearity and sensitivity to mechanical stimulation. Classically, P(open) is regulated by a calcium-sensitive adaptation mechanism in which lowering extracellular calcium or depolarization increases P(open). Recent data demonstrated that the fast component of adaptation is independent of both calcium and voltage, thus requiring an alternative explanation for the sensitivity of P(open) to calcium and voltage. Using rat auditory hair cells, we characterize a mechanism, separate from fast adaptation, whereby divalent ions interacting with the local lipid environment modulate resting P(open). The specificity of this effect for different divalent ions suggests binding sites that are not an EF-hand or calmodulin model. GsMTx4, a lipid-mediated modifier of cationic stretch-activated channels, eliminated the voltage and divalent sensitivity with minimal effects on adaptation. We hypothesize that the dual mechanisms (lipid modulation and adaptation) extend the dynamic range of the system while maintaining adaptation kinetics at their maximal rates.

  20. Gut microbiota Modulated by Probiotics and Garcinia cambogia Extract Correlate with Weight Gain and Adipocyte Sizes in High Fat-Fed Mice

    Science.gov (United States)

    Heo, Jaeyoung; Seo, Minseok; Park, Hwanhee; Lee, Woon Kyu; Guan, Le Luo; Yoon, Joon; Caetano-Anolles, Kelsey; Ahn, Hyeonju; Kim, Se-Young; Kang, Yoon-Mo; Cho, Seoae; Kim, Heebal

    2016-01-01

    Results of recent studies on gut microbiota have suggested that obesogenic bacteria exacerbate obesity and metabolic dysfunction in the host when fed a high fat diet (HFD). In order to explore obesity-associated bacterial candidates and their response to diet, the composition of faecal bacterial communities was investigated by analyzing 16S rRNA gene sequences in mice. Dietary intervention with probiotics and Garcinia cambogia extract attenuated weight gain and adipocyte size in HFD-fed mice. To identify obesity-causative microbiota, two statistical analyses were performed. Forty-eight bacterial species were found to overlap between the two analyses, indicating the commonly identified species as diet-driven and obesity-associated, which would make them strong candidates for host-microbiome interaction on obesity. Finally, correlation based network analysis between diet, microbe, and host revealed that Clostridium aminophilum, a hyper-ammonia-producing bacterium, was highly correlated with obesity phenotypes and other associated bacteria, and shown to be suppressed by the combination of probiotics and Garcinia cambogia extract. Results of the present study suggest that probiotics and Garcinia cambogia extract alleviate weight gain and adiposity, in part via differentially modulating the composition of gut microbiota in HFD fed mice. PMID:27658722

  1. Can adaptive modulation of traits to urban environments facilitate Ricinus communis L. invasiveness?

    Science.gov (United States)

    Goyal, Neha; Pardha-Saradhi, P; Sharma, Gyan P

    2014-11-01

    This paper addresses the phenotypic variation among Ricinus communis L. populations in four urban habitat types (road verges, garbage dumps, construction debris, and natural area) in Delhi, India, by evaluating important traits such as plant height, basal circumference, seeds per plant, seed size, seed weight, specific leaf area, and reproductive index. An important biochemical marker, proline, considered as a good plant performance indicator under stress was also quantified in leaves of R. communis to evaluate its response in different habitats. Interestingly, the species showed significant variation in plant height, specific leaf area, seed size, seed weight, and leaf proline content in different habitat types. Leaf proline content was positively related to plant height, specific leaf area, and seed size while negatively related to the total number of seeds/plant. Interestingly, reproductive index, calculated as a ratio of the total number of seeds to the plant height also showed a negative relation with leaf proline content. Results indicated that R. communis exhibits adaptive modulation of growth, reproductive traits, and leaf proline content in various urban habitats which contributes to invasiveness, range expansion, and establishment of the species. The study also gives evidence of how morphological and physiological traits could directly affect invasiveness of R. communis.

  2. [The diagnostics of adaptive reactions of blood on application the stress-modulating therapy in patients with brain chronic ischemia].

    Science.gov (United States)

    Krylov, V N; Deriugina, A V; Antipenko, E A; Zakharova, O A

    2012-12-01

    The article deals with the results of analysis of electrophoretic mobility of erythrocytes and leukogram in patients with dyscirculatory encephalopathy on different stages of disease on application therapy with inclusion of stress-modulating pharmaceuticals into course of treatment. It is established that the electrophoretic mobiliy of erythrocytes makes it possible to evaluate the adaptive indicators blood in patients with dyscirculatory encephalopathy. The consideration of these indicators makes feasible the substantiation of inclusion of stress-modulating therapy into complex treatment of patients with chronic cerebrovascular inefficiency. PMID:23479969

  3. Adaptive Optics with a Liquid-Crystal-on-Silicon Spatial Light Modulator and Its Behavior in Retinal Imaging

    Science.gov (United States)

    Shirai, Tomohiro; Takeno, Kohei; Arimoto, Hidenobu; Furukawa, Hiromitsu

    2009-07-01

    An adaptive optics system with a brand-new device of a liquid-crystal-on-silicon (LCOS) spatial light modulator (SLM) and its behavior in in vivo imaging of the human retina are described. We confirmed by experiments that closed-loop correction of ocular aberrations of the subject's eye was successfully achieved at the rate of 16.7 Hz in our system to obtain a clear retinal image in real time. The result suggests that an LCOS SLM is one of the promising candidates for a wavefront corrector in a prospective commercial ophthalmic instrument with adaptive optics.

  4. Design and Implementation of Adaptive Model Based Gain Scheduled Controller for a Real Time Non Linear System in LabVIEW

    Directory of Open Access Journals (Sweden)

    M. Kalyan Chakravarthi

    2015-05-01

    Full Text Available The aim of this study is to design and implement an Adaptive Model Based Gain Scheduled (AMBGS Controller using classical controller tuning techniques for a Single Spherical Nonlinear Tank System (SSTLLS. A varying range of development in the control mechanisms have been evidently seen in the last two decades. The control of level has always been a topic of discussion in the process control scenario. In this study a real time SSTLLS has been chosen for investigation. System identification of these different regions of nonlinear process is done using black box model, which is identified to be nonlinear and approximated to be a First Order plus Dead Time (FOPDT model. A proportional and integral controller is designed using LabVIEW and Skogestad’s and Ziegler Nichols (ZN tuning methods are implemented. The paper will provide details about the data acquisition unit, shows the implementation of the controller and compare the results of PI tuning methods used for an AMBGS Controller.

  5. An adaptive neuro fuzzy inference system controlled space cector pulse width modulation based HVDC light transmission system under AC fault conditions

    Science.gov (United States)

    Ajay Kumar, M.; Srikanth, N.

    2014-03-01

    In HVDC Light transmission systems, converter control is one of the major fields of present day research works. In this paper, fuzzy logic controller is utilized for controlling both the converters of the space vector pulse width modulation (SVPWM) based HVDC Light transmission systems. Due to its complexity in the rule base formation, an intelligent controller known as adaptive neuro fuzzy inference system (ANFIS) controller is also introduced in this paper. The proposed ANFIS controller changes the PI gains automatically for different operating conditions. A hybrid learning method which combines and exploits the best features of both the back propagation algorithm and least square estimation method is used to train the 5-layer ANFIS controller. The performance of the proposed ANFIS controller is compared and validated with the fuzzy logic controller and also with the fixed gain conventional PI controller. The simulations are carried out in the MATLAB/SIMULINK environment. The results reveal that the proposed ANFIS controller is reducing power fluctuations at both the converters. It also improves the dynamic performance of the test power system effectively when tested for various ac fault conditions.

  6. All-optical ultra-wideband doublet signal source based on the cross-gain modulation in a semiconductor optical amplifier

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zan-shan; LI Pei-li; ZHENG Jia-jin; PAN Ting-ting; HUANG Shi-jie; LUO You-hong

    2012-01-01

    We propose a novel scheme to generate the ultra-wideband (UWB) doublet signal pulse based on the cross-gain modulation (XGM) in a semiconductor optical amplifier (SOA).In the scheme,only an optical source and an SOA are needed.As there is only one wavelength included in the output doublet signal pulse,no time difference between the upper and down pulses is introduced during the transmission process.By using the software of Optisystem 7.0,the impacts of the optical power,the SOA current,the wavelength and the input signal pulse width on the generated doublet pulse are simulated and tudied numerically.The results show that when the pulse width of the input signal pulse is larger,the output signal pulse is better,and is insensitive to the change of wavelength.In addition,the ultra-wideband positive and negative monocycles can be generated by choosing suitable optical source power and SOA current.

  7. Adapt

    Science.gov (United States)

    Bargatze, L. F.

    2015-12-01

    Active Data Archive Product Tracking (ADAPT) is a collection of software routines that permits one to generate XML metadata files to describe and register data products in support of the NASA Heliophysics Virtual Observatory VxO effort. ADAPT is also a philosophy. The ADAPT concept is to use any and all available metadata associated with scientific data to produce XML metadata descriptions in a consistent, uniform, and organized fashion to provide blanket access to the full complement of data stored on a targeted data server. In this poster, we present an application of ADAPT to describe all of the data products that are stored by using the Common Data File (CDF) format served out by the CDAWEB and SPDF data servers hosted at the NASA Goddard Space Flight Center. These data servers are the primary repositories for NASA Heliophysics data. For this purpose, the ADAPT routines have been used to generate data resource descriptions by using an XML schema named Space Physics Archive, Search, and Extract (SPASE). SPASE is the designated standard for documenting Heliophysics data products, as adopted by the Heliophysics Data and Model Consortium. The set of SPASE XML resource descriptions produced by ADAPT includes high-level descriptions of numerical data products, display data products, or catalogs and also includes low-level "Granule" descriptions. A SPASE Granule is effectively a universal access metadata resource; a Granule associates an individual data file (e.g. a CDF file) with a "parent" high-level data resource description, assigns a resource identifier to the file, and lists the corresponding assess URL(s). The CDAWEB and SPDF file systems were queried to provide the input required by the ADAPT software to create an initial set of SPASE metadata resource descriptions. Then, the CDAWEB and SPDF data repositories were queried subsequently on a nightly basis and the CDF file lists were checked for any changes such as the occurrence of new, modified, or deleted

  8. Unequal Protection of Video Streaming through Adaptive Modulation with a Trizone Buffer over Bluetooth Enhanced Data Rate

    Directory of Open Access Journals (Sweden)

    Rouzbeh Razavi

    2007-12-01

    Full Text Available Bluetooth enhanced data rate wireless channel can support higher-quality video streams compared to previous versions of Bluetooth. Packet loss when transmitting compressed data has an effect on the delivered video quality that endures over multiple frames. To reduce the impact of radio frequency noise and interference, this paper proposes adaptive modulation based on content type at the video frame level and content importance at the macroblock level. Because the bit rate of protected data is reduced, the paper proposes buffer management to reduce the risk of buffer overflow. A trizone buffer is introduced, with a varying unequal protection policy in each zone. Application of this policy together with adaptive modulation results in up to 4 dB improvement in objective video quality compared to fixed rate scheme for an additive white Gaussian noise channel and around 10 dB for a Gilbert-Elliott channel. The paper also reports a consistent improvement in video quality over a scheme that adapts to channel conditions by varying the data rate without accounting for the video frame packet type or buffer congestion.

  9. Use of a spatial light modulator as an adaptable phase mask for wavefront coding

    OpenAIRE

    Carles, Guillem; Muyo, G; Bosch i Puig, Salvador; Harvey, A R

    2010-01-01

    A wavefront-coded imaging system employing a spatial light modulator (SLM) for the agile implementation of phase masks is presented. The SLM is a liquid crystal display that can be modulated to implement cubic phase masks of variable coding strength. These phase masks produce broad point spread functions insensitive to defocus aberration and are used in combination with post-detection digital image processing to extend the depth-of-field of an imaging system. A detailed description of the cal...

  10. Cross-layer designed adaptive modulation algorithm with packet combining and truncated ARQ over MIMO Nakagami fading channels

    KAUST Repository

    Aniba, Ghassane

    2011-04-01

    This paper presents an optimal adaptive modulation (AM) algorithm designed using a cross-layer approach which combines truncated automatic repeat request (ARQ) protocol and packet combining. Transmissions are performed over multiple-input multiple-output (MIMO) Nakagami fading channels, and retransmitted packets are not necessarily modulated using the same modulation format as in the initial transmission. Compared to traditional approach, cross-layer design based on the coupling across the physical and link layers, has proven to yield better performance in wireless communications. However, there is a lack for the performance analysis and evaluation of such design when the ARQ protocol is used in conjunction with packet combining. Indeed, previous works addressed the link layer performance of AM with truncated ARQ but without packet combining. In addition, previously proposed AM algorithms are not optimal and can provide poor performance when packet combining is implemented. Herein, we first show that the packet loss rate (PLR) resulting from the combining of packets modulated with different constellations can be well approximated by an exponential function. This model is then used in the design of an optimal AM algorithm for systems employing packet combining, truncated ARQ and MIMO antenna configurations, considering transmission over Nakagami fading channels. Numerical results are provided for operation with or without packet combining, and show the enhanced performance and efficiency of the proposed algorithm in comparison with existing ones. © 2011 IEEE.

  11. A dosimetric comparison of two-phase adaptive intensity-modulated radiotherapy for locally advanced nasopharyngeal cancer.

    Science.gov (United States)

    Chitapanarux, Imjai; Chomprasert, Kittisak; Nobnaop, Wannapa; Wanwilairat, Somsak; Tharavichitkul, Ekasit; Jakrabhandu, Somvilai; Onchan, Wimrak; Traisathit, Patrinee; Van Gestel, Dirk

    2015-05-01

    The purpose of this investigation was to evaluate the potential dosimetric benefits of a two-phase adaptive intensity-modulated radiotherapy (IMRT) protocol for patients with locally advanced nasopharyngeal cancer (NPC). A total of 17 patients with locally advanced NPC treated with IMRT had a second computed tomography (CT) scan after 17 fractions in order to apply and continue the treatment with an adapted plan after 20 fractions. To simulate the situation without adaptation, a hybrid plan was generated by applying the optimization parameters of the original treatment plan to the anatomy of the second CT scan. The dose-volume histograms (DVHs) and dose statistics of the hybrid plan and the adapted plan were compared. The mean volume of the ipsilateral and contralateral parotid gland decreased by 6.1 cm(3) (30.5%) and 5.4 cm(3) (24.3%), respectively. Compared with the hybrid plan, the adapted plan provided a higher dose to the target volumes with better homogeneity, and a lower dose to the organs at risk (OARs). The Dmin of all planning target volumes (PTVs) increased. The Dmax of the spinal cord and brainstem were lower in 94% of the patients (1.6-5.9 Gy, P < 0.001 and 2.1-9.9 Gy, P < 0.001, respectively). The Dmean of the contralateral parotid decreased in 70% of the patients (range, 0.2-4.4 Gy). We could not find a relationship between dose variability and weight loss. Our two-phase adaptive IMRT protocol improves dosimetric results in terms of target volumes and OARs in patients with locally advanced NPC. PMID:25666189

  12. SU-E-J-254: Utility of Pinnacle Dynamic Planning Module Utilizing Deformable Image Registration in Adaptive Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Jani, S [Sharp Memorial Hospital, San Diego, CA (United States)

    2014-06-01

    Purpose For certain highly conformal treatment techniques, changes in patient anatomy due to weight loss and/or tumor shrinkage can result in significant changes in dose distribution. Recently, the Pinnacle treatment planning system added a Dynamic Planning module utilizing Deformable Image Registration (DIR). The objective of this study was to evaluate the effectiveness of this software in adapting to altered anatomy and adjusting treatment plans to account for it. Methods We simulated significant tumor response by changing patient thickness and altered chin positions using a commercially-available head and neck (H and N) phantom. In addition, we studied 23 CT image sets of fifteen (15) patients with H and N tumors and eight (8) patients with prostate cancer. In each case, we applied deformable image registration through Dynamic Planning module of our Pinnacle Treatment Planning System. The dose distribution of the original CT image set was compared to the newly computed dose without altering any treatment parameter. Result was a dose if we did not adjust the plan to reflect anatomical changes. Results For the H and N phantom, a tumor response of up to 3.5 cm was correctly deformed by the Pinnacle Dynamic module. Recomputed isodose contours on new anatomies were within 1 mm of the expected distribution. The Pinnacle system configuration allowed dose computations resulting from original plans on new anatomies without leaving the planning system. Original and new doses were available side-by-side with both CT image sets. Based on DIR, about 75% of H and N patients (11/15) required a re-plan using new anatomy. Among prostate patients, the DIR predicted near-correct bladder volume in 62% of the patients (5/8). Conclusions The Dynamic Planning module of the Pinnacle system proved to be an accurate and useful tool in our ability to adapt to changes in patient anatomy during a course of radiotherapy.

  13. SU-E-J-254: Utility of Pinnacle Dynamic Planning Module Utilizing Deformable Image Registration in Adaptive Radiotherapy

    International Nuclear Information System (INIS)

    Purpose For certain highly conformal treatment techniques, changes in patient anatomy due to weight loss and/or tumor shrinkage can result in significant changes in dose distribution. Recently, the Pinnacle treatment planning system added a Dynamic Planning module utilizing Deformable Image Registration (DIR). The objective of this study was to evaluate the effectiveness of this software in adapting to altered anatomy and adjusting treatment plans to account for it. Methods We simulated significant tumor response by changing patient thickness and altered chin positions using a commercially-available head and neck (H and N) phantom. In addition, we studied 23 CT image sets of fifteen (15) patients with H and N tumors and eight (8) patients with prostate cancer. In each case, we applied deformable image registration through Dynamic Planning module of our Pinnacle Treatment Planning System. The dose distribution of the original CT image set was compared to the newly computed dose without altering any treatment parameter. Result was a dose if we did not adjust the plan to reflect anatomical changes. Results For the H and N phantom, a tumor response of up to 3.5 cm was correctly deformed by the Pinnacle Dynamic module. Recomputed isodose contours on new anatomies were within 1 mm of the expected distribution. The Pinnacle system configuration allowed dose computations resulting from original plans on new anatomies without leaving the planning system. Original and new doses were available side-by-side with both CT image sets. Based on DIR, about 75% of H and N patients (11/15) required a re-plan using new anatomy. Among prostate patients, the DIR predicted near-correct bladder volume in 62% of the patients (5/8). Conclusions The Dynamic Planning module of the Pinnacle system proved to be an accurate and useful tool in our ability to adapt to changes in patient anatomy during a course of radiotherapy

  14. 声纳前放模块幅度增益检测电路设计%Detection Circuit Design for Amplitude Gain of Sonar Pre-amplifier Module

    Institute of Scientific and Technical Information of China (English)

    温连峰; 李耀波; 曹黎明

    2016-01-01

    Amplitude gain is one of the most important performance indexes of pre-amplifier module .Amplitude gain is important for a sonar performance whether it is normal or not .In order to improve the detection efficiency of the amplitude gain of the pre-amplifier module ,a measurement circuit is designed based on modern electronic measurement technology and micro controller .The detection circuit can automatically realize the measurement of the amplitude gain of the pre-amplifier module and the measurement accuracy can meet the requirements ,so as to shorten the testing time and improve the efficiency of equipment maintenance and support .%幅度增益是声纳前置放大模块最重要的性能指标之一,其正常与否对声纳装备整体性能至关重要。为了提高前放模块幅度增益的检测效率,基于现代电子测量技术和微控制器设计了一种幅度增益测量电路。该检测电路能够自动实现前放模块的幅度增益技术指标的检测且测量精度满足要求,从而缩短测试诊断时间,提高了装备维修保障效率。

  15. Quadrature amplitude modulation from basics to adaptive trellis-coded turbo-equalised and space-time coded OFDM CDMA and MC-CDMA systems

    CERN Document Server

    Hanzo, Lajos

    2004-01-01

    "Now fully revised and updated, with more than 300 pages of new material, this new edition presents the wide range of recent developments in the field and places particular emphasis on the family of coded modulation aided OFDM and CDMA schemes. In addition, it also includes a fully revised chapter on adaptive modulation and a new chapter characterizing the design trade-offs of adaptive modulation and space-time coding." "In summary, this volume amalgamates a comprehensive textbook with a deep research monograph on the topic of QAM, ensuring it has a wide-ranging appeal for both senior undergraduate and postgraduate students as well as practicing engineers and researchers."--Jacket.

  16. 线性增益调制激光雷达系统参数对测距精度的影响%Influence of linear gain modulation lidar system parameters on ranging accuracy

    Institute of Scientific and Technical Information of China (English)

    张勇; 曹喜滨; 吴龙; 赵远

    2014-01-01

    Gain modulation scannerless lidar is a new system of lidar. It is significant to investigate the range resolution of the lidar system. Based on the gain modulation lidar distance expression, the relationship between gain modulation lidar system parameters and range accuracy is being under investigation. Both photon noise with the weak echo intensity and gain saturation of the microchannel plate with the high range accuracy were taken into account. Curve between ranging accuracy and echo power was given. Gain modulation scannerless lidar system has a interval of echo power. By adjusting parameters to manipulate echo power into this interval, the highest ranging accuracy can be obtained.%增益调制非扫描激光雷达是一种新体制的激光雷达,其测距精度的研究具有重要价值。从增益调制激光雷达距离表达式出发,研究了增益调制激光雷达各系统参数对于距离精度的影响关系,综合考虑了回波强度较低时的光子噪声和距离精度较高时微通道板的增益饱和带来的影像,给出了测距精度与回波功率的关系曲线,得到了增益调制无扫描激光雷达系统存在一个回波强度区间,通过调整系统参数控制回波强度在该区间内,可以保证系统获得最高的测距精度。

  17. Potentiating mGluR5 Function with a Positive Allosteric Modulator Enhances Adaptive Learning

    Science.gov (United States)

    Xu, Jian; Zhu, Yongling; Kraniotis, Stephen; He, Qionger; Marshall, John J.; Nomura, Toshihiro; Stauffer, Shaun R.; Lindsley, Craig W.; Conn, P. Jeffrey; Contractor, Anis

    2013-01-01

    Metabotropic glutamate receptor 5 (mGluR5) plays important roles in modulating neural activity and plasticity and has been associated with several neuropathological disorders. Previous work has shown that genetic ablation or pharmacological inhibition of mGluR5 disrupts fear extinction and spatial reversal learning, suggesting that mGluR5…

  18. Performance Evaluation of Wimax Physical Layer under Adaptive Modulation Techniques and Communication Channels

    CERN Document Server

    Islam, Md Ashraful; Hasan, Md Zahid

    2009-01-01

    Wimax (Worldwide Interoperability for Microwave Access) is a promising technology which can offer high speed voice, video and data service up to the customer end. The aim of this paper is the performance evaluation of an Wimax system under different combinations of digital modulation (BPSK, QPSK, 4 QAM and 16 QAM) and different communication channels AWGN and fading channels (Rayleigh and Rician). And the Wimax system incorporates Reed Solomon (RS) encoder with Convolutional encoder with half and two third rated codes in FEC channel coding. The simulation results of estimated Bit Error Rate (BER) displays that the implementation of interleaved RS code (255, 239, 8) with two third rated Convolutional code under BPSK modulation technique is highly effective to combat in the Wimax communication system. To complete this performance analysis in Wimax based systems, a segment of audio signal is used for analysis. The transmitted audio message is found to have retrieved effectively under noisy situation.

  19. Adaptive Light Modulation for Improved Resolution and Efficiency in All-Optical Pulse-Echo Ultrasound.

    Science.gov (United States)

    Alles, Erwin J; Colchester, Richard J; Desjardins, Adrien E

    2016-01-01

    In biomedical all-optical pulse-echo ultrasound systems, ultrasound is generated with the photoacoustic effect by illuminating an optically absorbing structure with a temporally modulated light source. Nanosecond range laser pulses are typically used, which can yield bandwidths exceeding 100 MHz. However, acoustical attenuation within tissue or nonuniformities in the detector or source power spectra result in energy loss at the affected frequencies and in a reduced overall system efficiency. In this work, a laser diode is used to generate linear and nonlinear chirp optical modulations that are extended to microsecond time scales, with bandwidths constrained to the system sensitivity. Compared to those obtained using a 2-ns pulsed laser, pulse-echo images of a phantom obtained using linear chirp excitation exhibit similar axial resolution (99 versus 92 μm, respectively) and signal-to-noise ratios (SNRs) (10.3 versus 9.6 dB). In addition, the axial point spread function (PSF) exhibits lower sidelobe levels in the case of chirp modulation. Using nonlinear (time-stretched) chirp excitations, where the nonlinearity is computed from measurements of the spectral sensitivity of the system, the power spectrum of the imaging system was flattened and its bandwidth broadened. Consequently, the PSF has a narrower axial extent and still lower sidelobe levels. Pulse-echo images acquired with time-stretched chirps as optical modulation have higher axial resolution (64 μm) than those obtained with linear chirps, at the expense of a lower SNR (6.8 dB). Using a linear or time-stretched chirp, the conversion efficiency from optical power to acoustical pressure improved by a factor of 70 or 61, respectively, compared to that obtained with pulsed excitation.

  20. Adaptive times : modulating time perception in neglect patients and healthy individuals

    OpenAIRE

    Kardinal, Mareike

    2014-01-01

    Are time and space linked in the brain? Over the past decades, there have been increasing indications for a spatial representation of time intervals. They come from time-space interference phenomena in healthy individuals and from observation of time deficits in patients with spatial neglect. While there are well-established treatment possibilities for visuospatial distortions in these patients, only few studies have examined time deficits and their possible modulation. If time and space proc...

  1. Systematic analysis of the kalimantacin assembly line NRPS module using an adapted targeted mutagenesis approach.

    Science.gov (United States)

    Uytterhoeven, Birgit; Appermans, Kenny; Song, Lijiang; Masschelein, Joleen; Lathouwers, Thomas; Michiels, Chris W; Lavigne, Rob

    2016-04-01

    Kalimantacin is an antimicrobial compound with strong antistaphylococcal activity that is produced by a hybrid trans-acyltransferase polyketide synthase/nonribosomal peptide synthetase system in Pseudomonas fluorescens BCCM_ID9359. We here present a systematic analysis of the substrate specificity of the glycine-incorporating adenylation domain from the kalimantacin biosynthetic assembly line by a targeted mutagenesis approach. The specificity-conferring code was adapted for use in Pseudomonas and mutated adenylation domain active site sequences were introduced in the kalimantacin gene cluster, using a newly adapted ligation independent cloning method. Antimicrobial activity screens and LC-MS analyses revealed that the production of the kalimantacin analogues in the mutated strains was abolished. These results support the idea that further insight in the specificity of downstream domains in nonribosomal peptide synthetases and polyketide synthases is required to efficiently engineer these strains in vivo. PMID:26666990

  2. A gain-coefficient switched Alexandrite laser

    NARCIS (Netherlands)

    Lee, C. J.; van der Slot, P. J. M.; Boller, K. J.

    2013-01-01

    We report on a gain-coefficient switched Alexandrite laser. An electro-optic modulator is used to switch between high and low gain states by making use of the polarization dependent gain of Alexandrite. In gain-coefficient switched mode, the laser produces 85 ns pulses with a pulse energy of 240 mJ

  3. Antenna subset selection at multi-antenna relay with adaptive modulation

    KAUST Repository

    Choi, Seyeong

    2011-06-01

    In this paper, we proposed several antenna selection schemes for cooperative diversity systems with adaptive transmission. The proposed schemes were based on dual-hop relaying where a relay with multiple-antenna capabilities at reception and transmission is deployed between the source and the destination nodes. We analyzed the performance of the proposed schemes by quantifying the average spectral efficiency and the outage probability. We also investigated the trade-off of performance and complexity by comparing the average number of active antennas, path estimations, and signal-to-noise ratio comparisons of the different proposed schemes. Copyright © 2011 John Wiley & Sons, Ltd.

  4. Wavefront response matrix for closed-loop adaptive optics system based on non-modulation pyramid wavefront sensor

    Science.gov (United States)

    Wang, Jianxin; Bai, Fuzhong; Ning, Yu; Li, Fei; Jiang, Wenhan

    2012-06-01

    Pyramid wavefront sensor (PWFS) is a kind of wavefront sensor with high spatial resolution and high energy utilization. In this paper an adaptive optics system with PWFS as wavefront sensor and liquid-crystal spatial light modulator (LC-SLM) as wavefront corrector is built in the laboratory. The wavefront response matrix is a key element in the close-loop operation. It can be obtained by measuring the real response to given aberrations, which is easily contaminated by noise and influenced by the inherent aberration in the optical system. A kind of analytic solution of response matrix is proposed, with which numerical simulation and experiment are also implemented to verify the performance of closed-loop correction of static aberration based on linear reconstruction theory. Results show that this AO system with the proposed matrix can work steadily in closed-loop operation.

  5. Experience Gained during the Adaptation of Classical ChE Subjects to the Bologna Plan in Europe: The Case of Chemical Reactors

    Science.gov (United States)

    Ponsa, Sergio; Sanchez, Antoni

    2011-01-01

    At present, due to the overall adaptation to the European Higher Education Area (EHEA), a new concept regarding the teaching methodology was thought to be essential for engineering subjects. In this paper we describe our experience teaching the altered content of the courses on two classical subjects; Chemical Reactors (Chemical Engineering) and…

  6. Forecasting the Cell Temperature of PV Modules with an Adaptive System

    Directory of Open Access Journals (Sweden)

    Giuseppina Ciulla

    2013-01-01

    Full Text Available The need to reduce energy consumptions and to optimize the processes of energy production has pushed the technology towards the implementation of hybrid systems for combined production of electric and thermal energies. In particular, recent researches look with interest at the installation of hybrid system PV/T. To improve the energy performance of these systems, it is necessary to know the operating temperature of the photovoltaic modules. The determination of the operating temperature is a key parameter for the assessment of the actual performance of photovoltaic panels. In the literature, it is possible to find different correlations that evaluate the referring to standard test conditions and/or applying some theoretical simplifications/assumptions. Nevertheless, the application of these different correlations, for the same conditions, does not lead to unequivocal results. In this work an alternative method, based on the employment of artificial neural networks (ANNs, was proposed to predict the operating temperature of a PV module. This methodology does not require any simplification or physical assumptions. In the paper is described the ANN that obtained the best performance: a multilayer perception network. The results have been compared with experimental monitored data and with some of the most cited empirical correlations proposed by different authors.

  7. Performance analysis of joint multi-branch switched diversity and adaptive modulation schemes for spectrum sharing systems

    KAUST Repository

    Bouida, Zied

    2012-12-01

    Under the scenario of an underlay cognitive radio network, we propose in this paper two adaptive schemes using switched transmit diversity and adaptive modulation in order to increase the spectral efficiency of the secondary link and maintain a desired performance for the primary link. The proposed switching efficient scheme (SES) and bandwidth efficient scheme (BES) use the scan and wait combining technique (SWC) where a transmission occurs only when a branch with an acceptable performance is found, otherwise data is buffered. In these schemes, the modulation constellation size and the used transmit branch are determined to minimize the average number of switched branches and to achieve the highest spectral efficiency given the fading channel conditions, the required error rate performance, and a peak interference constraint to the primary receiver (PR). For delay-sensitive applications, we also propose two variations of the SES and BES schemes using power control (SES-PC and BES-PC) where the secondary transmitter (ST) starts sending data using a nominal power level which is selected in order to minimize the average delay introduced by the SWC technique. We demonstrate through numerical examples that the BES scheme increases the capacity of the secondary link when compared to the SES scheme. This spectral efficiency improvement comes at the expense of an increased average number of switched branches and thus an increased average delay. We also show that the SES-PC and the BES-PC schemes minimize the average delay while satisfying the same spectral efficiency as the SES and BES schemes, respectively. © 2012 IEEE.

  8. Signaling and Adaptation Modulate the Dynamics of the Photosensoric Complex of Natronomonas pharaonis.

    Directory of Open Access Journals (Sweden)

    Philipp S Orekhov

    2015-10-01

    Full Text Available Motile bacteria and archaea respond to chemical and physical stimuli seeking optimal conditions for survival. To this end transmembrane chemo- and photoreceptors organized in large arrays initiate signaling cascades and ultimately regulate the rotation of flagellar motors. To unravel the molecular mechanism of signaling in an archaeal phototaxis complex we performed coarse-grained molecular dynamics simulations of a trimer of receptor/transducer dimers, namely NpSRII/NpHtrII from Natronomonas pharaonis. Signaling is regulated by a reversible methylation mechanism called adaptation, which also influences the level of basal receptor activation. Mimicking two extreme methylation states in our simulations we found conformational changes for the transmembrane region of NpSRII/NpHtrII which resemble experimentally observed light-induced changes. Further downstream in the cytoplasmic domain of the transducer the signal propagates via distinct changes in the dynamics of HAMP1, HAMP2, the adaptation domain and the binding region for the kinase CheA, where conformational rearrangements were found to be subtle. Overall these observations suggest a signaling mechanism based on dynamic allostery resembling models previously proposed for E. coli chemoreceptors, indicating similar properties of signal transduction for archaeal photoreceptors and bacterial chemoreceptors.

  9. Joint multiuser switched diversity and adaptive modulation schemes for spectrum sharing systems

    KAUST Repository

    Qaraqe, Marwa

    2012-12-01

    In this paper, we develop multiuser access schemes for spectrum sharing systems whereby secondary users are allowed to share the spectrum with primary users under the condition that the interference observed at the primary receiver is below a predetermined threshold. In particular, we devise two schemes for selecting a user among those that satisfy the interference constraint and achieve an acceptable signal-to-noise ratio level. The first scheme selects the user that reports the best channel quality. In order to alleviate the high feedback load associated with the first scheme, we develop a second scheme based on the concept of switched diversity where the base station scans the users in a sequential manner until an acceptable user is found. In addition to these two selection schemes, we consider two power adaptive settings at the secondary users based on the amount of interference available at the secondary transmitter. In the On/Off power setting, users are allowed to transmit based on whether the interference constraint is met or not, while in the full power adaptive setting, the users are allowed to vary their transmission power to satisfy the interference constraint. Finally, we present numerical results for our proposed algorithms where we show the trade-off between the average spectral efficiency and average feedback load for both schemes. © 2012 IEEE.

  10. Performance analysis of a rate adaptive multi-band ultra-wideband system based on quadrature fractal modulation scheme

    Institute of Scientific and Technical Information of China (English)

    LI Yu-hong; ZHOU Zheng

    2005-01-01

    A rate adaptive multi-band ultra-wideband (UWB) system based on the quadrature fractal modulation (QFM)scheme was proposed. Exploring the use of homogeneous signals as modulating waveforms in UWB system, the signal within each 528MHz sub-band was divided into 8 different frequency bandwidths using wavelets transform and these data sequences to be transmitted were embedded into homogeneous waveforms. It is found that the use of homogeneous signals in such UWB system is quite feasible, leadings to a novel multi-rate diversity strategy. Within each 528MHz sub-band, the UWB-QFM system can provide much higher data rates than that of the UWB orthogonal frequency division multiplexing (OFDM) system. Simulation results also show that the bit error rate (BER) performance of the UWB-QFM system achieves a greatly improvement over existing UWB-OFDM system. Due to the fractal properties of the homogeneous signals, these data sequences to be transmitted can be recovered using arbitrarily short receiver signal.

  11. Joint Adaptive Modulation Coding and Cooperative ARQ over Relay Channels-Applications to Land Mobile Satellite Communications

    CERN Document Server

    Mardani, Morteza; Lahouti, Farshad; Eliasi, Behrouz

    2008-01-01

    In a cooperative relay network, a relay node (R) facilitates data transmission to the destination node (D), when the latter is unable to decode the source node (S) data correctly. This paper considers such a system model and presents a cross-layer approach to jointly design adaptive modulation and coding (AMC) at the physical layer and cooperative truncated automatic repeat request (ARQ) protocol at the data link layer. We first derive a closed form expression for the spectral efficiency of the joint cooperative ARQ-AMC scheme. Aiming at maximizing this performance measure, we then optimize two AMC schemes for S-D and R-D links, which directly satisfy a prescribed packet loss rate constraint. As an interesting application, we also consider the problem of joint link adaptation and blockage mitigation in land mobile satellite communications (LMSC). We also present a new relay-assisted transmission protocol for LMSC, which delivers the source data to the destination via the relaying link, when the S-D channel is...

  12. Dose reduction in spiral CT angiography of thoracic outlet syndrome by anatomically adapted tube current modulation

    Energy Technology Data Exchange (ETDEWEB)

    Mastora, I.; Remy-Jardin, M.; Remy, J. [Dept. of Radiology, University Center Hospital Calmette, Lille (France); Medical Research Group, Lille (France); Suess, C.; Scherf, C. [Siemens Medical Systems, Forcheim (Germany); Guillot, J.P. [Dept. of Radiology, University Center Hospital Calmette, Lille (France)

    2001-04-01

    The aim of this study was to evaluate dose reduction in spiral CT angiography of the thoracic outlet by on-line tube-current control. Prospectively, 114 patients undergoing spiral CT angiography of the subclavian artery for thoracic outlet arterial syndromes were evaluated with and without tube-current modulation at the same session (scanning parameters for the two successive angiograms, one in the neutral position and one after the postural maneuver): 140 kV; 206 mA; scan time 0.75 s; collimation 3 mm; pitch = (1). The dose reduction system was applied in the neutral position in the first 92 consecutive patients and after postural maneuver in the remaining 22 consecutive patients. Dose reduction and image quality were analyzed in the overall study group (group 1; n = 114). The influence of the arm position was assessed in 44 of the 114 patients (group 2), matched by the transverse diameter of the upper thorax. The mean dose reduction was 33 % in group 1 (range 22-40 %) and 34 % in group 2 (range 26-40 %). In group 2 the only difference in image quality was a significantly higher frequency of graininess on low-dose scans compared with reference scans whatever the patient's arm position, graded as minimal in 38 of the 44 patients (86 %). When the low-dose technique was applied after postural maneuver in group 2: (a) the mean dose reduction was significantly higher (35 vs 32 % in the neutral position; p = 0.006); (b) graininess was less frequent (82 vs 91 % in the neutral position); and (c) the percentage of graininess graded as minimal was significantly higher (83 vs 70 % in the neutral position; p = 0.2027). On-line tube-current modulation enables dose reduction on high-quality, diagnostic spiral CT angiograms of the thoracic outlet and should be applied during data acquisition in the neutral position and after postural maneuver for optimal use. (orig.)

  13. VNTR-DAT1 and COMTVal158Met Genotypes Modulate Mental Flexibility and Adaptive Behavior Skills in Down Syndrome

    Science.gov (United States)

    del Hoyo, Laura; Xicota, Laura; Langohr, Klaus; Sánchez-Benavides, Gonzalo; de Sola, Susana; Cuenca-Royo, Aida; Rodriguez, Joan; Rodríguez-Morató, Jose; Farré, Magí; Dierssen, Mara; de la Torre, Rafael; Cuenca-Royo, Aida

    2016-01-01

    Down syndrome (DS) is an aneuploidy syndrome that is caused by trisomy for human chromosome 21 resulting in a characteristic cognitive and behavioral phenotype, which includes executive functioning and adaptive behavior difficulties possibly due to prefrontal cortex (PFC) deficits. DS also present a high risk for early onset of Alzheimer Disease-like dementia. The dopamine (DA) system plays a neuromodulatory role in the activity of the PFC. Several studies have implicated trait differences in DA signaling on executive functioning based on genetic polymorphisms in the genes encoding for the catechol-O-methyltransferase (COMTVal158Met) and the dopamine transporter (VNTR-DAT1). Since it is known that the phenotypic consequences of genetic variants are modulated by the genetic background in which they occur, we here explore whether these polymorphisms variants interact with the trisomic genetic background to influence gene expression, and how this in turn mediates DS phenotype variability regarding PFC cognition. We genotyped 69 young adults of both genders with DS, and found that VNTR-DAT1 was in Hardy-Weinberg equilibrium but COMTVal158Met had a reduced frequency of Met allele homozygotes. In our population, genotypes conferring higher DA availability, such as Met allele carriers and VNTR-DAT1 10-repeat allele homozygotes, resulted in improved performance in executive function tasks that require mental flexibility. Met allele carriers showed worse adaptive social skills and self-direction, and increased scores in the social subscale of the Dementia Questionnaire for People with Intellectual Disabilities than Val allele homozygotes. The VNTR-DAT1 was not involved in adaptive behavior or early dementia symptoms. Our results suggest that genetic variants of COMTVal158Met and VNTR-DAT1 may contribute to PFC-dependent cognition, while only COMTVal158Met is involved in behavioral phenotypes of DS, similar to euploid population. PMID:27799900

  14. Adaptive modulation of adult brain gray and white matter to high altitude: structural MRI studies.

    Directory of Open Access Journals (Sweden)

    Jiaxing Zhang

    Full Text Available The aim of this study was to investigate brain structural alterations in adult immigrants who adapted to high altitude (HA. Voxel-based morphometry analysis of gray matter (GM volumes, surface-based analysis of cortical thickness, and Tract-Based Spatial Statistics analysis of white matter fractional anisotropy (FA based on MRI images were conducted on 16 adults (20-22 years who immigrated to the Qinghai-Tibet Plateau (2300-4400 m for 2 years. They had no chronic mountain sickness. Control group consisted of 16 matched sea level subjects. A battery of neuropsychological tests was also conducted. HA immigrants showed significantly decreased GM volumes in the right postcentral gyrus and right superior frontal gyrus, and increased GM volumes in the right middle frontal gyrus, right parahippocampal gyrus, right inferior and middle temporal gyri, bilateral inferior ventral pons, and right cerebellum crus1. While there was some divergence in the left hemisphere, surface-based patterns of GM changes in the right hemisphere resembled those seen for VBM analysis. FA changes were observed in multiple WM tracts. HA immigrants showed significant impairment in pulmonary function, increase in reaction time, and deficit in mental rotation. Parahippocampal and middle frontal GM volumes correlated with vital capacity. Superior frontal GM volume correlated with mental rotation and postcentral GM correlated with reaction time. Paracentral lobule and frontal FA correlated with mental rotation reaction time. There might be structural modifications occurred in the adult immigrants during adaptation to HA. The changes in GM may be related to impaired respiratory function and psychological deficits.

  15. An extract of chokeberry attenuates weight gain and modulates multiple signaling pathways in epididymal adipose tissue of rats fed a fructose-rich diet

    Science.gov (United States)

    Chokeberries are a rich source of anthocyanins, which may contribute to the prevention of obesity and metabolic syndrome. The aim of this study was to determine if an extract from chokeberries would reduce weight gain in rats fed a fructose-rich diet, and to explore the potential mechanisms related...

  16. 高频增益符号未知时的变结构模型参考自适应控制%Variable Structure Model Reference Adaptive Control with Unknown High Frequency Gain Sign

    Institute of Scientific and Technical Information of China (English)

    董文瀚; 孙秀霞; 林岩

    2007-01-01

    A variable structure model reference adaptive control for plants with relative degree greater than one and unknown high frequency gain sign is proposed. A switching scheme is introduced based on a monitoring function designed for the first auxiliary error of the close loop system. It is shown that under the supervision of the monitoring function, the switching stops after at most a finite number of switchings and the tracking error converges to a residual set that can be made arbitrarily small by appropriately choosing some design parameters.

  17. Morphological adaptation and protein modulation of myotendinous junction following moderate aerobic training.

    Science.gov (United States)

    Curzi, Davide; Baldassarri, Valentina; De Matteis, Rita; Salamanna, Francesca; Bolotta, Alessandra; Frizziero, Antonio; Fini, Milena; Marini, Marina; Falcieri, Elisabetta

    2015-04-01

    Myotendinous junction is the muscle-tendon interface through which the contractile force can be transferred from myofibrils to the tendon extracellular matrix. At the ultrastructural level, aerobic training can modify the distal myotendinous junction of rat gastrocnemius, increasing the contact area between tissues. The aim of this work is to investigate the correlation between morphological changes and protein modulation of the myotendinous junction following moderate training. For this reason, talin, vinculin and type IV collagen amount and spatial distribution were investigated by immunohistochemistry and confocal microscopy. The images were then digitally analyzed by evaluating fluorescence intensity. Morphometric analysis revealed a significant increased thickening of muscle basal lamina in the trained group (53.1 ± 0.4 nm) with respect to the control group (43.9 ± 0.3 nm), and morphological observation showed the presence of an electron-dense area in the exercised muscles, close to the myotendinous junction. Protein concentrations appeared significantly increased in the trained group (talin +22.2%; vinculin +22.8% and type IV collagen +11.8%) with respect to the control group. Therefore, our findings suggest that moderate aerobic training induces/causes morphological changes at the myotendinous junction, correlated to the synthesis of structural proteins of the muscular basal lamina and of the cytoskeleton.

  18. Adaptive antenna system for OFDMA WiMAX radio-over-fiber links using a directly modulated R-SOA and optical filtering

    DEFF Research Database (Denmark)

    Presi, Marco; Prince, Kamau; Chiuchiarelli, Andrea;

    2009-01-01

    We implement an adaptive beam steering system based on a directly-modulated unseeded reflective SOA. this system allows the distribution of 2.4 GHz 64-QAM OFDMA signals with 2048-subcarriers (72 Mb/s) satisfying the IEEE 802.16e specifications...

  19. Adaptive cytoprotection through modulation of nitric oxide in ethanol-evoked gastritis

    Institute of Scientific and Technical Information of China (English)

    Joshua Ka-Shun Ko; Chi-Hin Cho; Shiu-Kum Lam

    2004-01-01

    AIM: To assess the mechanisms of protective action by different mild irritants through maintenance of gastric mucosal integrity and modulation of mucosal nitric oxide (NO) in experimental gastritis rats.METHODS: Either 200 ml/L ethanol, 50 g/L NaCl or 0.3 mol/LHCl was pretreated to normal or 800 mL/L ethanol-induced acute gastritis Sprague-Dawley rats before a subsequent challenge with 500 mL/L ethanol. Both macroscopic lesion areas and histological damage scores were determined in the gastric mucosa of each group of animals. Besides,gastric mucosal activities of NO synthase isoforms and of superoxide dismutase, along with mucosal level of leukotriene (LT)C4 were measured.RESULTS: Macroscopic mucosal damages were protected by 200 mL/L ethanol and 50 g/L NaCl in gastritis rats.However, although 200 mL/L ethanol could protect the surface layers of mucosal cells in normal animals (protection attenuated by NG-nitro-L-arginine methyl ester), no cytoprotection against deeper histological damages was found in gastritis rats. Besides, inducible NO synthase activity was increased in the mucosa of gastritis animals and unaltered by mild irritants. Nevertheless, the elevation in mucosal LTC4 level following 500 mL/L ethanol administration and under gastritis condition was significantly reduced by pretreatment of all three mild irritants in both normal and gastritis animals.CONCLUSION: These findings suggest that the aggravated 500 mL/L ethanol-evoked mucosal damages under gastritis condition could be due to increased inducible NO and LTC4 production in the gastric mucosa. Only 200 mL/L ethanol is truly "cytoprotective" at the surface glandular level of nongastritis mucosa. Furthermore, the macroscopic protection of the three mild irritants involves reduction of LTC4 level in both normal and gastritis mucosa, implicating preservation of the vasculature.

  20. Improvement of Quality of Service (QoS in MISO-OFDM Systems Using Superposition Based Adaptive Modulation (SPAM and Space Frequency Block Coding (SFBC Technique

    Directory of Open Access Journals (Sweden)

    K.Vinoth Babu

    2013-06-01

    Full Text Available 4G based wireless communication systems require high data rate with high QoS with minimal system complexity. In wireless environment, as the effect of multipath fading increases, Bit Error Rate (BER also increases. To offer high data rate, the bandwidth has to be increased which is a limited resource. The best possible solution for obtaining high data rate is to combine Multi Input Multi Output (MIMO with OFDM. To ameliorate the performance of MIMO-OFDM systems over multipath fading channels, we use the concept of SFBC which retrieves the orthogonality property of OFDM signals in frequency selective fading channels. In frequency selective fading environment, adaptive modulation gives better performance than fixed modulated systems but with increased decoding complexity. Adaptive modulation implemented with SPAM offers less decoding complexity. Adaptive modulation combined with diversity schemes still improves the reliability of the system. In this paper, SPAM based SFBC is proposed with OFDM to give better performance with less decoding complexity. From the Simulationresults we can conclude that proposed system will have better performance compared to fixed modulated systems.

  1. 自适应传感器模块(ASIM)设计%Design of an adaptive sensor interface module

    Institute of Scientific and Technical Information of China (English)

    吴亮; 侯立刚

    2015-01-01

    A design that transforms a variety of different types of sensors interfaces into a standardized USB port is pro⁃posed based on FPGA to achieve the fast reading and writing of the data collected though sensor interface by the host PC. The implementation method of USB controller based on hardware description language of Verilog is described. An adaptive system module is build by the application of QuartusⅡ and NiosⅡ software. The system is verified by the data transmission. The method of transforming UART port into USB port is simulated.%基于FPGA提出一种将各种不同类型的传感器接口(如UART接口)转化为统一规范的USB接口的设计方案,从而实现PC机对传感器接口采集的数据快速读写。简单介绍USB控制器的Verilog HDL实现方法,并应用Quartus Ⅱ和Nios Ⅱ软件搭建自适应传感器系统模块,通过数据传输对该系统进行验证,模拟了UART接口转换为USB接口的实现方法。

  2. A Practical Adaptive TuCM Scheme for Rayleigh Flat Fading Channels

    Institute of Scientific and Technical Information of China (English)

    伍守豪; 宋文涛

    2004-01-01

    A practical adaptive turbo coded modulation (TuCM) scheme was proposed and its adaptive method was described. With some hardware considerations, a suboptimal optimization algorithm that the number of fading regions is variable was put forward. Furthermore, the cutoff fade depth of power adaptation was modified to reduce the interruption probability. The results show that the proposed adaptive TuCM comes within 3 dB of Rayleigh fading channel capacity, and exhibits about 3 dB power gain relative to the conventional adaptive trellis-coded modulation (TCM), and is easy to realize by hardware.

  3. Analysis of reactor power behaviour using estimation of period for the gain adaptation in a state feedback controller; Atomos para el desarrollo de Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Benitez R, J.S. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico); Perez C, J.H. [CINVESTAV, IPN, A.P. 14740 07000 Mexico D.F. (Mexico); Rivero G, T. [ITT, 50140 Metepec, Estado de Mexico (Mexico)

    2008-07-01

    In this paper a novel procedure for power regulation in a TRIGA Mark III nuclear reactor is presented. The control scheme combines state variable feedback with a first order predictor, which is incorporated to speed up the power response of the reactor without exceeding the safety requirement imposed by the reactor period. The simulation results using the proposed control strategy attains different values of steady-state power from different values of initial power in short time, complying at all times with the safety restriction imposed on the reactor period. The predictor, derived from the theory of first order numerical integration, produces very good results during the ascent of power. These results include a fast response and independence of the wide variety of potential operating conditions something not easy and even impossible to obtain with other procedures. By using this control scheme, the reactor period is maintained within safety limits during the start up of the reactor, which is normally the operating condition where an occurrence of a period scram is common. However, the predictor can not be used when the power is reaching the desired power level because the instantaneous power increases far above the desired level. Thus, when the power increases above certain power level, the state feedback gain is set constant to a predefined value. This causes some oscillations that decrease in a few seconds. Afterwards, the power response smoothly approaches, with a small overshoot, the desired power. This constraint on the use of the predictor prevents the unbounded increase of the neutron power. The control law proposed requires all the system's state variables. Since only the neutron power is available, it is necessary the estimation of the non measurable states. The key issue of the existence of a solution to this problem has been previously considered. One of the conclusions is that the point kinetic equations are observable under certain restrictions

  4. Simulation of time-dependent energy modulation by wake fields and its impact on gain in the VUV free electron laser of the TESLA Test Facility

    International Nuclear Information System (INIS)

    For shorter bunches and narrower undulator gaps the interaction between the electrons in the bunch and the wake fields becomes so large that the FEL amplification is affected. For a typical vacuum chamber of an X-ray or VUV Free Electron Laser three major sources of wake fields exist: a resistance of the beam pipe, a change in the geometric aperture and the surface roughness of the beam pipe. The generated wake fields, which move along with the electrons, change the electron energy and momentum, depending on the electron longitudinal and transverse position. In particular, the accumulated energy modulation shifts the electrons away from the resonance condition. Based on an analytic model the energy loss by the wake fields has been incorporated into the time-dependent FEL simulation code GENESIS 1.3. For the parameters of the TESLA Test Facility the influence of the bunch length, beam pipe diameter and surface roughness has been studied. The results are presented in this paper

  5. Simulation of time-dependent energy modulation by wake fields and its impact on gain in the VUV free electron laser of the TESLA Test Facility

    CERN Document Server

    Reiche, S

    2000-01-01

    For shorter bunches and narrower undulator gaps the interaction between the electrons in the bunch and the wake fields becomes so large that the FEL amplification is affected. For a typical vacuum chamber of an X-ray or VUV Free Electron Laser three major sources of wake fields exist: a resistance of the beam pipe, a change in the geometric aperture and the surface roughness of the beam pipe. The generated wake fields, which move along with the electrons, change the electron energy and momentum, depending on the electron longitudinal and transverse position. In particular, the accumulated energy modulation shifts the electrons away from the resonance condition. Based on an analytic model the energy loss by the wake fields has been incorporated into the time-dependent FEL simulation code GENESIS 1.3. For the parameters of the TESLA Test Facility the influence of the bunch length, beam pipe diameter and surface roughness has been studied. The results are presented in this paper.

  6. Graphene Oxides Decorated with Carnosine as an Adjuvant To Modulate Innate Immune and Improve Adaptive Immunity in Vivo.

    Science.gov (United States)

    Meng, Chunchun; Zhi, Xiao; Li, Chao; Li, Chuanfeng; Chen, Zongyan; Qiu, Xusheng; Ding, Chan; Ma, Lijun; Lu, Hongmin; Chen, Di; Liu, Guangqing; Cui, Daxiang

    2016-02-23

    Current studies have revealed the immune effects of graphene oxide (GO) and have utilized them as vaccine carriers and adjuvants. However, GO easily induces strong oxidative stress and inflammatory reaction at the site of injection. It is very necessary to develop an alternative adjuvant based on graphene oxide derivatives for improving immune responses and decreasing side effects. Carnosine (Car) is an outstanding and safe antioxidant. Herein, the feasibility and efficiency of ultrasmall graphene oxide decorated with carnosine as an alternative immune adjuvant were explored. OVA@GO-Car was prepared by simply mixing ovalbumin (OVA, a model antigen) with ultrasmall GO covalently modified with carnosine (GO-Car). We investigated the immunological properties of the GO-Car adjuvant in model mice. Results show that OVA@GO-Car can promote robust and durable OVA-specific antibody response, increase lymphocyte proliferation efficiency, and enhance CD4(+) T and CD8(+) T cell activation. The presence of Car in GO also probably contributes to enhancing the antigen-specific adaptive immune response through modulating the expression of some cytokines, including IL-6, CXCL1, CCL2, and CSF3. In addition, the safety of GO-Car as an adjuvant was evaluated comprehensively. No symptoms such as allergic response, inflammatory redness swelling, raised surface temperatures, physiological anomalies of blood, and remarkable weight changes were observed. Besides, after modification with carnosine, histological damages caused by GO-Car in lung, muscle, kidney, and spleen became weaken significantly. This study sufficiently suggest that GO-Car as a safe adjuvant can effectively enhance humoral and innate immune responses against antigens in vivo. PMID:26766427

  7. Graphene Oxides Decorated with Carnosine as an Adjuvant To Modulate Innate Immune and Improve Adaptive Immunity in Vivo.

    Science.gov (United States)

    Meng, Chunchun; Zhi, Xiao; Li, Chao; Li, Chuanfeng; Chen, Zongyan; Qiu, Xusheng; Ding, Chan; Ma, Lijun; Lu, Hongmin; Chen, Di; Liu, Guangqing; Cui, Daxiang

    2016-02-23

    Current studies have revealed the immune effects of graphene oxide (GO) and have utilized them as vaccine carriers and adjuvants. However, GO easily induces strong oxidative stress and inflammatory reaction at the site of injection. It is very necessary to develop an alternative adjuvant based on graphene oxide derivatives for improving immune responses and decreasing side effects. Carnosine (Car) is an outstanding and safe antioxidant. Herein, the feasibility and efficiency of ultrasmall graphene oxide decorated with carnosine as an alternative immune adjuvant were explored. OVA@GO-Car was prepared by simply mixing ovalbumin (OVA, a model antigen) with ultrasmall GO covalently modified with carnosine (GO-Car). We investigated the immunological properties of the GO-Car adjuvant in model mice. Results show that OVA@GO-Car can promote robust and durable OVA-specific antibody response, increase lymphocyte proliferation efficiency, and enhance CD4(+) T and CD8(+) T cell activation. The presence of Car in GO also probably contributes to enhancing the antigen-specific adaptive immune response through modulating the expression of some cytokines, including IL-6, CXCL1, CCL2, and CSF3. In addition, the safety of GO-Car as an adjuvant was evaluated comprehensively. No symptoms such as allergic response, inflammatory redness swelling, raised surface temperatures, physiological anomalies of blood, and remarkable weight changes were observed. Besides, after modification with carnosine, histological damages caused by GO-Car in lung, muscle, kidney, and spleen became weaken significantly. This study sufficiently suggest that GO-Car as a safe adjuvant can effectively enhance humoral and innate immune responses against antigens in vivo.

  8. WE-G-BRF-01: Adaptation to Intrafraction Tumor Deformation During Intensity-Modulated Radiotherapy: First Proof-Of-Principle Demonstration

    International Nuclear Information System (INIS)

    Purpose: Intrafraction tumor deformation limits targeting accuracy in radiotherapy and cannot be adapted to by current motion management techniques. This study simulated intrafractional treatment adaptation to tumor deformations using a dynamic Multi-Leaf Collimator (DMLC) tracking system during Intensity-modulated radiation therapy (IMRT) treatment for the first time. Methods: The DMLC tracking system was developed to adapt to the intrafraction tumor deformation by warping the planned beam aperture guided by the calculated deformation vector field (DVF) obtained from deformable image registration (DIR) at the time of treatment delivery. Seven single phantom deformation images up to 10.4 mm deformation and eight tumor system phantom deformation images up to 21.5 mm deformation were acquired and used in tracking simulation. The intrafraction adaptation was simulated at the DMLC tracking software platform, which was able to communicate with the image registration software, reshape the instantaneous IMRT field aperture and log the delivered MLC fields.The deformation adaptation accuracy was evaluated by a geometric target coverage metric defined as the sum of the area incorrectly outside and inside the reference aperture. The incremental deformations were arbitrarily determined to take place equally over the delivery interval. The geometric target coverage of delivery with deformation adaptation was compared against the delivery without adaptation. Results: Intrafraction deformation adaptation during dynamic IMRT plan delivery was simulated for single and system deformable phantoms. For the two particular delivery situations, over the treatment course, deformation adaptation improved the target coverage by 89% for single target deformation and 79% for tumor system deformation compared with no-tracking delivery. Conclusion: This work demonstrated the principle of real-time tumor deformation tracking using a DMLC. This is the first step towards the development of an

  9. Stochastic resonance in a gain-noise model of a single-mode laser driven by pump noise and quantum noise with cross-correlation between real and imaginary parts under direct signal modulation

    Institute of Scientific and Technical Information of China (English)

    Chen Li-Mei; Cao Li; Wu Da-Jin

    2007-01-01

    Stochastic resonance (SR) is studied in a gain-noise model of a single-mode laser driven by a coloured pump noise and a quantum noise with cross-correlation between real and imaginary parts under a direct signal modulation. By using a linear approximation method, we find that the SR appears during the variation of signal-to-noise ratio (SNR)separately with the pump noise self-correlation time τ, the noise correlation coefficient between the real part and the imaginary part of the quantum noise λq, the attenuation coefficient γ and the deterministic steady-state intensity I0.In addition, it is found that the SR can be characterized not only by the dependence of SNR on the noise variables of τand λq, but also by the dependence of SNR on the laser system variables of γ and I0. Thus our investigation extends the characteristic quantity of SR proposed before.

  10. Circadian adaptation to night shift work influences sleep, performance, mood and the autonomic modulation of the heart.

    Directory of Open Access Journals (Sweden)

    Philippe Boudreau

    Full Text Available Our aim was to investigate how circadian adaptation to night shift work affects psychomotor performance, sleep, subjective alertness and mood, melatonin levels, and heart rate variability (HRV. Fifteen healthy police officers on patrol working rotating shifts participated to a bright light intervention study with 2 participants studied under two conditions. The participants entered the laboratory for 48 h before and after a series of 7 consecutive night shifts in the field. The nighttime and daytime sleep periods were scheduled during the first and second laboratory visit, respectively. The subjects were considered "adapted" to night shifts if their peak salivary melatonin occurred during their daytime sleep period during the second visit. The sleep duration and quality were comparable between laboratory visits in the adapted group, whereas they were reduced during visit 2 in the non-adapted group. Reaction speed was higher at the end of the waking period during the second laboratory visit in the adapted compared to the non-adapted group. Sleep onset latency (SOL and subjective mood levels were significantly reduced and the LF∶HF ratio during daytime sleep was significantly increased in the non-adapted group compared to the adapted group. Circadian adaptation to night shift work led to better performance, alertness and mood levels, longer daytime sleep, and lower sympathetic dominance during daytime sleep. These results suggest that the degree of circadian adaptation to night shift work is associated to different health indices. Longitudinal studies are required to investigate long-term clinical implications of circadian misalignment to atypical work schedules.

  11. Circadian Adaptation to Night Shift Work Influences Sleep, Performance, Mood and the Autonomic Modulation of the Heart

    Science.gov (United States)

    Boudreau, Philippe; Dumont, Guy A.; Boivin, Diane B.

    2013-01-01

    Our aim was to investigate how circadian adaptation to night shift work affects psychomotor performance, sleep, subjective alertness and mood, melatonin levels, and heart rate variability (HRV). Fifteen healthy police officers on patrol working rotating shifts participated to a bright light intervention study with 2 participants studied under two conditions. The participants entered the laboratory for 48 h before and after a series of 7 consecutive night shifts in the field. The nighttime and daytime sleep periods were scheduled during the first and second laboratory visit, respectively. The subjects were considered “adapted” to night shifts if their peak salivary melatonin occurred during their daytime sleep period during the second visit. The sleep duration and quality were comparable between laboratory visits in the adapted group, whereas they were reduced during visit 2 in the non-adapted group. Reaction speed was higher at the end of the waking period during the second laboratory visit in the adapted compared to the non-adapted group. Sleep onset latency (SOL) and subjective mood levels were significantly reduced and the LF∶HF ratio during daytime sleep was significantly increased in the non-adapted group compared to the adapted group. Circadian adaptation to night shift work led to better performance, alertness and mood levels, longer daytime sleep, and lower sympathetic dominance during daytime sleep. These results suggest that the degree of circadian adaptation to night shift work is associated to different health indices. Longitudinal studies are required to investigate long-term clinical implications of circadian misalignment to atypical work schedules. PMID:23923024

  12. 线性增益调制激光雷达系统参数对测距精度的影响%Influence of linear gain modulation lidar system parameters on range accuracy

    Institute of Scientific and Technical Information of China (English)

    张勇; 曹喜滨; 吴龙; 赵远

    2013-01-01

    测距精度是激光雷达系统的重要参数,测距精度影响因素的研究对于提高激光雷达系统性能具有重要价值.增益调制无扫描激光雷达是一种新体制的激光雷达,其测距精度的影响因素不同于传统飞行时间测量的激光雷达系统.从增益调制激光雷达距离表达式出发,推导了增益调制激光雷达各系统参数对于距离精度的影响,综合考虑了ICCD的调制误差、回波强度较低时的光子噪声、探测器噪声、微通道板的增益饱和等因素,给出了测距精度与回波功率的关系曲线.得出增益调制无扫描激光雷达系统存在一个回波强度区间,在该强度区间内,无扫描激光雷达的测距精度是区间外的2倍以上.%Range accuracy is one of the most important parameters in a radar system.Research on the influence of range accuracy has an important value to improve the laser performance of radar.As a novel lidar system,linear gain modulation scannerless lidar acquires range information from image intensity by using the technique of range-intensity mapping.The relationship between range resolution and lidar system parameters was under investigated,taking different factors into consideration,including the modulation error of ICCD,the photonic noise at low echo intensity,the detector noise,and the gain saturation of micro channel plate.This paper presents that,within a certain region of echo signal power,range resolution can be improved by over twice that of outside the region,leading to great improvements of lidar system performance.

  13. Sub-module Short Circuit Fault Diagnosis in Modular Multilevel Converter Based on Wavelet Transform and Adaptive Neuro Fuzzy Inference System

    DEFF Research Database (Denmark)

    Liu, Hui; Loh, Poh Chiang; Blaabjerg, Frede

    2015-01-01

    by employing wavelet transform under different fault conditions. Then the fuzzy logic rules are automatically trained based on the fuzzified fault features to diagnose the different faults. Neither additional sensor nor the capacitor voltages are needed in the proposed method. The high accuracy, good...... for continuous operation and post-fault maintenance. In this article, a fault diagnosis technique is proposed for the short circuit fault in a modular multi-level converter sub-module using the wavelet transform and adaptive neuro fuzzy inference system. The fault features are extracted from output phase voltage...

  14. Synchrony between orientation-selective neurons is modulated during adaptation-induced plasticity in cat visual cortex

    Directory of Open Access Journals (Sweden)

    Shumikhina Svetlana

    2008-07-01

    Full Text Available Abstract Background Visual neurons respond essentially to luminance variations occurring within their receptive fields. In primary visual cortex, each neuron is a filter for stimulus features such as orientation, motion direction and velocity, with the appropriate combination of features eliciting maximal firing rate. Temporal correlation of spike trains was proposed as a potential code for linking the neuronal responses evoked by various features of a same object. In the present study, synchrony strength was measured between cells following an adaptation protocol (prolonged exposure to a non-preferred stimulus which induce plasticity of neurons' orientation preference. Results Multi-unit activity from area 17 of anesthetized adult cats was recorded. Single cells were sorted out and (1 orientation tuning curves were measured before and following 12 min adaptation and 60 min after adaptation (2 pairwise synchrony was measured by an index that was normalized in relation to the cells' firing rate. We first observed that the prolonged presentation of a non-preferred stimulus produces attractive (58% and repulsive (42% shifts of cell's tuning curves. It follows that the adaptation-induced plasticity leads to changes in preferred orientation difference, i.e. increase or decrease in tuning properties between neurons. We report here that, after adaptation, the neuron pairs that shared closer tuning properties display a significant increase of synchronization. Recovery from adaptation was accompanied by a return to the initial synchrony level. Conclusion We conclude that synchrony reflects the similarity in neurons' response properties, and varies accordingly when these properties change.

  15. PAPR reduction for OFDM systems with adaptive modulation%利用自适应调制进行OFDM系统PAPR抑制

    Institute of Scientific and Technical Information of China (English)

    胡登鹏; 石峰; 王世练; 张尔扬

    2012-01-01

    根据相同的信息比特采用不同调制样式时所得的正交频分复用( OFDM)信号的峰均功率比(PAPR)不同,提出了一种利用自适应调制进行OFDM系统PAPR抑制的算法,并设计了利用该算法的OFDM系统.算法通过设定一个可选调制样式集合,改变发端信息比特的调制样式,选择具有最小PAPR值的OFDM信号作为传输的OFDM信号,从而使整个系统的PAPR得到抑制.在接收端,通过对OFDM符号的调制样式进行识别,完成对调制信息解调.由于算法不需要传输需严格保护的边带信息,系统具有较强的可靠性和抗干扰能力.仿真结果表明,利用自适应调制可有效地进行OFDM系统PAPR抑制;同已有算法相比,在多径信道下,利用该算法的OFDM系统的误码率性能总体上较好.%This paper proposes a PAPR reduction algorithm for OFDM systems with adaptive modulation, which is based on the fact that an OFDM symbol has different PAPR when its modulation type is changed, and designs an OFDM system. A group of modulation type is set to be the candidate and the OFDM symbol' s modulation type is changed according to the group. The one with the minimal peak power is selected as the output signal. In receiver, the information bit can be demodulated after the modulation type detection. As there is no side information which should be strictly protected, the system is more reliable and robust. Simulation results show that it is effective for PAPR reduction with adaptive modulation in OFDM systems, and the proposed algorithm's system has better bit error ratio performances than previously algorithms as a whole.

  16. Optical UWB pulse generator using an N tap microwave photonic filter and phase inversion adaptable to different pulse modulation formats.

    Science.gov (United States)

    Bolea, Mario; Mora, José; Ortega, Beatriz; Capmany, José

    2009-03-30

    We propose theoretically and demonstrate experimentally an optical architecture for flexible Ultra-Wideband pulse generation. It is based on an N-tap reconfigurable microwave photonic filter fed by a laser array by using phase inversion in a Mach-Zehnder modulator. Since a large number of positive and negative coefficients can be easily implemented, UWB pulses fitted to the FCC mask requirements can be generated. As an example, a four tap pulse generator is experimentally demonstrated which complies with the FCC regulation. The proposed pulse generator allows different pulse modulation formats since the amplitude, polarity and time delay of generated pulse is controlled. PMID:19333263

  17. Adaptation and Evaluation of Online Self-learning Modules to Teach Critical Appraisal and Evidence-Based Practice in Nursing: An International Collaboration.

    Science.gov (United States)

    Gagnon, Johanne; Gagnon, Marie-Pierre; Buteau, Rose-Anne; Azizah, Ginette Mbourou; Jetté, Sylvie; Lampron, Amélie; Simonyan, David; Asua, José; Reviriego, Eva

    2015-07-01

    Healthcare professionals need to update their knowledge and acquire skills to continually inform their practice based on scientific evidence. This study was designed to evaluate online self-learning modules on critical appraisal skills to promote the use of research in clinical practice among nurses from Quebec (Canada) and the Basque Country (Spain). The teaching material was developed in Quebec and adapted to the Basque Country as part of an international collaboration project. A prospective pre-post study was conducted with 36 nurses from Quebec and 47 from the Basque Country. Assessment comprised the administration of questionnaires before and after the course in order to explore the main intervention outcomes: knowledge acquisition and self-learning readiness. Satisfaction was also measured at the end of the course. Two of the three research hypotheses were confirmed: (1) participants significantly improved their overall knowledge score after the educational intervention; and (2) they were, in general, satisfied with the course, giving it a rating of seven out of 10. Participants also reported a greater readiness for self-directed learning after the course, but this result was not significant in Quebec. The study provides unique knowledge on the cultural adaptation of online self-learning modules for teaching nurses about critical appraisal skills and evidence-based practice. PMID:25978538

  18. Tuning macro-twinned domain sizes and the b-variants content of the adaptive 14-modulated martensite in epitaxial Ni-Mn-Ga films by co-sputtering

    OpenAIRE

    Tillier, Jérémy; Bourgault, Daniel; Odier, Philippe; Ortega, Luc; Pairis, Sébastien; Fruchart, Olivier; Caillault, Nathalie; Carbone, Laurent

    2011-01-01

    International audience In order to obtain modulated-martensite in our epitaxial Ni-Mn-Ga films, we have tuned the composition by using a co-sputtering process. Here we present how the composition affects the variant distribution of the 14-modulated martensite at room temperature. The nature of such modulated-martensites is still strongly debated for magnetic shape memory alloys. It has been very recently demonstrated that the modulated-martensites in Ni-Mn-Ga are adaptive phases. The resul...

  19. Regulatory modulation of the T-box gene Tbx5 links development, evolution, and adaptation of the sternum

    OpenAIRE

    Bickley, Sorrel R. B.; Logan, Malcolm P. O.

    2014-01-01

    The fin-to-limb transition and acquisition of sterna were critical steps in the evolution of tetrapods, but despite the importance of the sternum in enabling quadrupedal locomotion and avian flight, the mechanisms controlling acquisition and evolutionary adaptation of sterna are not understood. Furthermore, the mechanisms that underlie sternum development and sternal defects are not known. We describe T-box transcription factor gene Tbx5 function in sternum formation, how disruption of TBX5 c...

  20. Gain ranging amplifier

    International Nuclear Information System (INIS)

    A gain ranging amplifier system is provided for use in the acquisition of data. Voltage offset compensation is utilized to correct errors in the gain ranging amplifier system caused by thermal drift and temperature dependent voltage offsets, both of which are associated with amplifiers in the gain ranging amplifier system

  1. Lipoxin A₄ modulates adaptive immunity by decreasing memory B-cell responses via an ALX/FPR2-dependent mechanism.

    Science.gov (United States)

    Ramon, Sesquile; Bancos, Simona; Serhan, Charles N; Phipps, Richard P

    2014-02-01

    Specialized proresolving mediators are endogenous bioactive lipid molecules that play a fundamental role in the regulation of inflammation and its resolution. Lipoxins and other specialized proresolving mediators have been identified in important immunological tissues including bone marrow, spleen, and blood. Lipoxins regulate functions of the innate immune system including the promotion of monocyte recruitment and increase macrophage phagocytosis of apoptotic neutrophils. A major knowledge gap is whether lipoxins influence adaptive immune cells. Here, we analyzed the actions of lipoxin A₄ (LXA₄) and its receptor ALX/FPR2 on human and mouse B cells. LXA₄ decreased IgM and IgG production on activated human B cells through ALX/FPR2-dependent signaling, which downregulated NF-κB p65 nuclear translocation. LXA₄ also inhibited human memory B-cell antibody production and proliferation, but not naïve B-cell function. Lastly, LXA₄ decreased antigen-specific antibody production in an OVA immunization mouse model. To our knowledge, this is the first description of the actions of lipoxins on human B cells, demonstrating a link between resolution signals and adaptive immunity. Regulating antibody production is crucial to prevent unwanted inflammation. Harnessing the ability of lipoxins to decrease memory B-cell antibody production can be beneficial to threat inflammatory and autoimmune disorders.

  2. Novel Link Adaptation Schemes for OFDM System

    Institute of Scientific and Technical Information of China (English)

    LEI Ming; CAI Peng; XU Yue-shan; ZHANG Ping

    2003-01-01

    Orthogonal Frequency Division Multiplexing (OFDM) is the most promising technique supporting the high data rate transmission. The combination of the link adaptation and OFDM can further increase the spectral efficiency. In this paper, we put forward two link adaptation schemes for OFDM system which have the advantages of both flexibility and practicability. Both of the two novel link adaptation schemes are based on the iterative mechanism to allocate the bit and power to subcarriers according to their channel gains and noisy levels which are assumed to be already known at the transmitter. The candidate modulation modes are determined freely before the link adaptation schemes are performed. The distinction between the two novel link adaptation schemes is that in the novel scheme A, the modulation mode is upgraded to the neighboring higher-order mode, while in the novel scheme B the modulation is upgraded to the genuine optimal mode. Therefore, the novel scheme A has the advantage of lower complexity and the novel scheme B has the advantage of higher spectral efficiency.

  3. 4.5-Gb/s RGB-LED based WDM visible light communication system employing CAP modulation and RLS based adaptive equalization.

    Science.gov (United States)

    Wang, Yiguang; Huang, Xingxing; Tao, Li; Shi, Jianyang; Chi, Nan

    2015-05-18

    Inter-symbol interference (ISI) is one of the key problems that seriously limit transmission data rate in high-speed VLC systems. To eliminate ISI and further improve the system performance, series of equalization schemes have been widely investigated. As an adaptive algorithm commonly used in wireless communication, RLS is also suitable for visible light communication due to its quick convergence and better performance. In this paper, for the first time we experimentally demonstrate a high-speed RGB-LED based WDM VLC system employing carrier-less amplitude and phase (CAP) modulation and recursive least square (RLS) based adaptive equalization. An aggregate data rate of 4.5Gb/s is successfully achieved over 1.5-m indoor free space transmission with the bit error rate (BER) below the 7% forward error correction (FEC) limit of 3.8x10(-3). To the best of our knowledge, this is the highest data rate ever achieved in RGB-LED based VLC systems. PMID:26074612

  4. Blood coagulation factor XII drives adaptive immunity during neuroinflammation via CD87-mediated modulation of dendritic cells.

    Science.gov (United States)

    Göbel, Kerstin; Pankratz, Susann; Asaridou, Chloi-Magdalini; Herrmann, Alexander M; Bittner, Stefan; Merker, Monika; Ruck, Tobias; Glumm, Sarah; Langhauser, Friederike; Kraft, Peter; Krug, Thorsten F; Breuer, Johanna; Herold, Martin; Gross, Catharina C; Beckmann, Denise; Korb-Pap, Adelheid; Schuhmann, Michael K; Kuerten, Stefanie; Mitroulis, Ioannis; Ruppert, Clemens; Nolte, Marc W; Panousis, Con; Klotz, Luisa; Kehrel, Beate; Korn, Thomas; Langer, Harald F; Pap, Thomas; Nieswandt, Bernhard; Wiendl, Heinz; Chavakis, Triantafyllos; Kleinschnitz, Christoph; Meuth, Sven G

    2016-01-01

    Aberrant immune responses represent the underlying cause of central nervous system (CNS) autoimmunity, including multiple sclerosis (MS). Recent evidence implicated the crosstalk between coagulation and immunity in CNS autoimmunity. Here we identify coagulation factor XII (FXII), the initiator of the intrinsic coagulation cascade and the kallikrein-kinin system, as a specific immune cell modulator. High levels of FXII activity are present in the plasma of MS patients during relapse. Deficiency or pharmacologic blockade of FXII renders mice less susceptible to experimental autoimmune encephalomyelitis (a model of MS) and is accompanied by reduced numbers of interleukin-17A-producing T cells. Immune activation by FXII is mediated by dendritic cells in a CD87-dependent manner and involves alterations in intracellular cyclic AMP formation. Our study demonstrates that a member of the plasmatic coagulation cascade is a key mediator of autoimmunity. FXII inhibition may provide a strategy to combat MS and other immune-related disorders. PMID:27188843

  5. Dynamic properties of a pulse-pumped fiber laser with a short, high-gain cavity

    Science.gov (United States)

    Yang, Chaolin; Guo, Junhong; Wei, Pu; Wan, Hongdan; Xu, Ji; Wang, Jin

    2016-09-01

    We demonstrate a pulsed high-gain all-fiber laser without intracavity modulators, where a short and heavily Erbium-doped fiber is used as the gain medium in a ring cavity. By pulsed-pumping this short high gain cavity and tuning an intracavity variable optical coupler, the laser generates optical pulses with a pulse-width of μs at a repetition rate in the order of kHz down to one-shot operation. Furthermore, dynamic properties of this laser are investigated theoretically based on a traveling-wave-model, in which an adaptive-discrete-grid-finite-difference-method is applied. The simulation results validate the experimental results. The demonstrated pulsed laser is compact, flexible and cost-effective, which will have great potential for applications in all-optical sensing and communication systems.

  6. Impossible expectations: fMRI adaptation in the lateral occipital complex (LOC) is modulated by the statistical regularities of 3D structural information.

    Science.gov (United States)

    Freud, Erez; Ganel, Tzvi; Avidan, Galia

    2015-11-15

    fMRI adaptation (fMRIa), the attenuation of fMRI signal which follows repeated presentation of a stimulus, is a well-documented phenomenon. Yet, the underlying neural mechanisms supporting this effect are not fully understood. Recently, short-term perceptual expectations, induced by specific experimental settings, were shown to play an important modulating role in fMRIa. Here we examined the role of long-term expectations, based on 3D structural statistical regularities, in the modulation of fMRIa. To this end, human participants underwent fMRI scanning while performing a same-different task on pairs of possible (regular, expected) objects and spatially impossible (irregular, unexpected) objects. We hypothesized that given the spatial irregularity of impossible objects in relation to real-world visual experience, the visual system would always generate a prediction which is biased to the possible version of the objects. Consistently, fMRIa effects in the lateral occipital cortex (LOC) were found for possible, but not for impossible objects. Additionally, in alternating trials the order of stimulus presentation modulated LOC activity. That is, reduced activation was observed in trials in which the impossible version of the object served as the prime object (i.e. first object) and was followed by the possible version compared to the reverse order. These results were also supported by the behavioral advantage observed for trials that were primed by possible objects. Together, these findings strongly emphasize the importance of perceptual expectations in object representation and provide novel evidence for the role of real-world statistical regularities in eliciting fMRIa.

  7. High-resolution pulmonary ventilation and perfusion PET/CT allows for functionally adapted intensity modulated radiotherapy in lung cancer

    International Nuclear Information System (INIS)

    Background and purpose: To assess the utility of functional lung avoidance using IMRT informed by four-dimensional (4D) ventilation/perfusion (V/Q) PET/CT. Materials and methods: In a prospective clinical trial, patients with non-small cell lung cancer (NSCLC) underwent 4D-V/Q PET/CT scanning before 60 Gy of definitive chemoradiation. Both “highly perfused” (HPLung) and “highly ventilated” (HVLung) lung volumes were delineated using a 70th centile SUV threshold, and a “ventilated lung volume” (VLung) was created using a 50th centile SUV threshold. For each patient four IMRT plans were created, optimised to the anatomical lung, HPLung, HVLung and VLung volumes, respectively. Improvements in functional dose volumetrics when optimising to functional volumes were assessed using mean lung dose (MLD), V5, V10, V20, V30, V40, V50 and V60 parameters. Results: The study cohort consisted of 20 patients with 80 IMRT plans. Plans optimised to HPLung resulted in a significant reduction of functional MLD by a mean of 13.0% (1.7 Gy), p = 0.02. Functional V5, V10 and V20 were improved by 13.2%, 7.3% and 3.8% respectively (p-values < 0.04). There was no significant sparing of dose to functional lung when adapting to VLung or HVLung. Plan quality was highly consistent with a mean PTV D95 and D5 ranging from 60.8 Gy to 61.0 Gy and 63.4 Gy to 64.5 Gy, respectively, and mean conformity and heterogeneity index ranging from 1.11 to 1.17 and 0.94 to 0.95, respectively. Conclusion: IMRT plans adapted to perfused but not ventilated lung on 4D-V/Q PET/CT allowed for reduced dose to functional lung whilst maintaining consistent plan quality

  8. Contribution of the modulation of intensity and the optimization to deliver a dose adapted to the biological heterogeneities

    International Nuclear Information System (INIS)

    The recent progress in functional imaging by Positron Emission Tomography (TEP) opens new perspectives in the delineation of target volumes in radiotherapy. The functional data is major; we can intend to adapt the irradiation doses on the tumor activity (TA) and to perform a dose escalation. Our objectives were (i) to characterize the TEP threshold, by quantifying the uncertainties of the target volume contour according to the lesion size and the threshold contour level, (ii) to set up the geometry suited to perform a high-precision irradiation based on the TA, (iii) to estimate the dosimetric impact of this new protocol and (iv) to verify that dosimetry is perfectly distributed. Three original phantoms were specially created to satisfy the constraints met, as well as two virtual phantoms containing 3 dose levels (dose level 3 = TA). Our results showed the importance of the effect threshold-volume on the planning in radiotherapy. To use this irradiation method, the diameter of 1 cm for the third level was able to be reached. A dose escalation of 20 Gy was possible between the second (70 Gy) and the third level (90 Gy). The dosimetric impact estimated on two real cases was suitable - increase of COIN (conformal index) from 0.6 to 0.8 and decrease of NTCP (normal tissue complication probability) of a factor 5 -. In absolute and relative dosimetry, the clinical tolerances were respected. So all the treatment process, going from the diagnosis with the TEP to reveal the TA, to the patient treatment made beforehand on phantom, and going through the ballistic and the dose calculation, was estimated and validated according to our objective to adapt the irradiation to the biological heterogeneities. However such high doses should be carefully estimated before being prescribed clinically and progress is also expected in imaging, because the minimal size which we can irradiate is on the limit of the resolution TEP. (author)

  9. Verification of the CENTRM Module for Adaptation of the SCALE Code to NGNP Prismatic and PBR Core Designs

    Energy Technology Data Exchange (ETDEWEB)

    Ganapol, Barry; Maldonado, Ivan

    2014-01-23

    The generation of multigroup cross sections lies at the heart of the very high temperature reactor (VHTR) core design, whether the prismatic (block) or pebble-bed type. The design process, generally performed in three steps, is quite involved and its execution is crucial to proper reactor physics analyses. The primary purpose of this project is to develop the CENTRM cross-section processing module of the SCALE code package for application to prismatic or pebble-bed core designs. The team will include a detailed outline of the entire processing procedure for application of CENTRM in a final report complete with demonstration. In addition, they will conduct a thorough verification of the CENTRM code, which has yet to be performed. The tasks for this project are to: Thoroughly test the panel algorithm for neutron slowing down; Develop the panel algorithm for multi-materials; Establish a multigroup convergence 1D transport acceleration algorithm in the panel formalism; Verify CENTRM in 1D plane geometry; Create and test the corresponding transport/panel algorithm in spherical and cylindrical geometries; and, Apply the verified CENTRM code to current VHTR core design configurations for an infinite lattice, including assessing effectiveness of Dancoff corrections to simulate TRISO particle heterogeneity.

  10. Verification of the CENTRM Module for Adaptation of the SCALE Code to NGNP Prismatic and PBR Core Designs

    International Nuclear Information System (INIS)

    The generation of multigroup cross sections lies at the heart of the very high temperature reactor (VHTR) core design, whether the prismatic (block) or pebble-bed type. The design process, generally performed in three steps, is quite involved and its execution is crucial to proper reactor physics analyses. The primary purpose of this project is to develop the CENTRM cross-section processing module of the SCALE code package for application to prismatic or pebble-bed core designs. The team will include a detailed outline of the entire processing procedure for application of CENTRM in a final report complete with demonstration. In addition, they will conduct a thorough verification of the CENTRM code, which has yet to be performed. The tasks for this project are to: Thoroughly test the panel algorithm for neutron slowing down; Develop the panel algorithm for multi-materials; Establish a multigroup convergence 1D transport acceleration algorithm in the panel formalism; Verify CENTRM in 1D plane geometry; Create and test the corresponding transport/panel algorithm in spherical and cylindrical geometries; and, Apply the verified CENTRM code to current VHTR core design configurations for an infinite lattice, including assessing effectiveness of Dancoff corrections to simulate TRISO particle heterogeneity

  11. Volume and dosimetric variations during two-phase adaptive intensity-modulated radiotherapy for locally advanced nasopharyngeal carcinoma.

    Science.gov (United States)

    Wang, Rui-hao; Zhang, Shu-xu; Zhou, Ling-hong; Zhang, Guo-qian; Yu, Hui; Lin, Xiao-dan; Lin, Shengqu

    2014-01-01

    The aims of this study were to evaluate the volume and dosimetric variations during IMRT for locally advanced NPC and to identify the benefits of a two-phase adaptive IMRT method. Twenty patients with locally advanced NPC having received IMRT treatment were included. Each patient had both an initial planning CT (CT-1) and a repeated CT scan (CT-2) after treatment at a dose of 40 Gy. Three IMRT planning scenarios were compared: (1) the initial plan on the CT-1 (plan-1); (2) the hybrid plan recalculated the initial plan on the CT-2 (plan-2); (3) the replan generated on the CT-2 being used to complete the course of IMRT (plan-3). The mean gross target volume and mean volumes of the positive neck lymph nodes, high-risk clinical target volume, and the left and right parotid glands significantly decreased by 30.2%, 45.1%, 21.1%, 14.7% and 18.2%, respectively on the CT-2. Comparing plan-2 with plan-1, the dose coverage of the targets remained unchanged, whereas the dose delivered to the parotid glands and spinal cord increased significantly. These patients with locally advanced NPC might benefit from replanning because of the sparing of the parotid glands and spinal cord. PMID:24212016

  12. Glucose-Modulated Mitochondria Adaptation in Tumor Cells: A Focus on ATP Synthase and Inhibitor Factor 1

    Directory of Open Access Journals (Sweden)

    Irene Mavelli

    2012-02-01

    Full Text Available Warburg’s hypothesis has been challenged by a number of studies showing that oxidative phosphorylation is repressed in some tumors, rather than being inactive per se. Thus, treatments able to shift energy metabolism by activating mitochondrial pathways have been suggested as an intriguing basis for the optimization of antitumor strategies. In this study, HepG2 hepatocarcinoma cells were cultivated with different metabolic substrates under conditions mimicking “positive” (activation/biogenesis or “negative” (silencing mitochondrial adaptation. In addition to the expected up-regulation of mitochondrial biogenesis, glucose deprivation caused an increase in phosphorylating respiration and a rise in the expression levels of the ATP synthase β subunit and Inhibitor Factor 1 (IF1. Hyperglycemia, on the other hand, led to a markedly decreased level of the transcriptional coactivator PGC-α suggesting down-regulation of mitochondrial biogenesis, although no change in mitochondrial mass and no impairment of phosphorylating respiration were observed. Moreover, a reduction in mitochondrial networking and in ATP synthase dimer stability was produced. No effect on β-ATP synthase expression was elicited. Notably, hyperglycemia caused an increase in IF1 expression levels, but it did not alter the amount of IF1 associated with ATP synthase. These results point to a new role of IF1 in relation to high glucose utilization by tumor cells, in addition to its well known effect upon mitochondrial ATP synthase regulation.

  13. Should I Gain Weight?

    Science.gov (United States)

    ... Can I Help a Friend Who Cuts? Should I Gain Weight? KidsHealth > For Teens > Should I Gain Weight? Print A A A Text Size ... Healthy Habits Matter en español ¿Debería ganar peso? "I want to play hockey, like I did in ...

  14. Health gain versus equity.

    Science.gov (United States)

    Scott-Samuel, A

    1992-05-01

    A new organisation, the Association for Public Health, has just been formed 'to help deliver real health gain for the population'. Alex Scott-Samuel suggests that the concept of 'health gain' is counter to health equality and needs wider debate. PMID:1624317

  15. Experimental demonstration of real-time adaptively modulated DDO-OFDM systems with a high spectral efficiency up to 5.76bit/s/Hz transmission over SMF links.

    Science.gov (United States)

    Chen, Ming; He, Jing; Tang, Jin; Wu, Xian; Chen, Lin

    2014-07-28

    In this paper, a FPGAs-based real-time adaptively modulated 256/64/16QAM-encoded base-band OFDM transceiver with a high spectral efficiency up to 5.76bit/s/Hz is successfully developed, and experimentally demonstrated in a simple intensity-modulated direct-detection optical communication system. Experimental results show that it is feasible to transmit a raw signal bit rate of 7.19Gbps adaptively modulated real-time optical OFDM signal over 20km and 50km single mode fibers (SMFs). The performance comparison between real-time and off-line digital signal processing is performed, and the results show that there is a negligible power penalty. In addition, to obtain the best transmission performance, direct-current (DC) bias voltage for MZM and launch power into optical fiber links are explored in the real-time optical OFDM systems.

  16. The mammalian efferent vestibular system plays a crucial role in the high-frequency response and short-term adaptation of the vestibuloocular reflex.

    Science.gov (United States)

    Hübner, Patrick P; Khan, Serajul I; Migliaccio, Americo A

    2015-12-01

    Although anatomically well described, the functional role of the mammalian efferent vestibular system (EVS) remains unclear. Unlike in fish and reptiles, the mammalian EVS does not seem to play a role in modulation of primary afferent activity in anticipation of active head movements. However, it could play a role in modulating long-term mechanisms requiring plasticity such as vestibular adaptation. We measured the efficacy of vestibuloocular reflex (VOR) adaptation in α9-knockout mice. These mice carry a missense mutation of the gene encoding the α9 nicotinic acetylcholine receptor (nAChR) subunit. The α9 nAChR subunit is expressed in the vestibular and auditory periphery, and its loss of function could compromise peripheral input from the predominantly cholinergic EVS. We measured the VOR gain (eye velocity/head velocity) in 26 α9-knockout mice and 27 cba129 control mice. Mice were randomly assigned to one of three groups: gain-increase adaptation (1.5×), gain-decrease adaptation (0.5×), or no adaptation (baseline, 1×). After adaptation training (horizontal rotations at 0.5 Hz with peak velocity 20°/s), we measured the sinusoidal (0.2-10 Hz, 20-100°/s) and transient (1,500-6,000°/s(2)) VOR in complete darkness. α9-Knockout mice had significantly lower baseline gains compared with control mice. This difference increased with stimulus frequency (∼ 5% 1 Hz). Moreover, vestibular adaptation (difference in VOR gain of gain-increase and gain-decrease adaptation groups as % of gain increase) was significantly reduced in α9-knockout mice (17%) compared with control mice (53%), a reduction of ∼ 70%. Our results show that the loss of α9 nAChRs moderately affects the VOR but severely affects VOR adaptation, suggesting that the EVS plays a crucial role in vestibular plasticity. PMID:26424577

  17. Effects of adaptation of vestibulo-ocular reflex function on manual target localization

    Science.gov (United States)

    Bloomberg, J. J.; Merkle, L. A.; Barry, S. R.; Huebner, W. P.; Cohen, H. S.; Mueller, S. A.; Fordice, J.

    2000-01-01

    The goal of the present study was to determine if adaptive modulation of vestibulo-ocular reflex (VOR) function is associated with commensurate alterations in manual target localization. To measure the effects of adapted VOR on manual responses we developed the Vestibular-Contingent Pointing Test (VCP). In the VCP test, subjects pointed to a remembered target following passive whole body rotation in the dark. In the first experiment, subjects performed VCP before and after wearing 0.5X minifying lenses that adaptively attenuate horizontal VOR gain. Results showed that adaptive reduction in horizontal VOR gain was accompanied by a commensurate change in VCP performance. In the second experiment, bilaterally labyrinthine deficient (LD) subjects were tested to confirm that vestibular cues were central to the spatial coding of both eye and hand movements during VCP. LD subjects performed significantly worse than normal subjects. These results demonstrate that adaptive change in VOR can lead to alterations in manual target localization.

  18. Cross-Layer Approach using k-NN Based Adaptive Modulation Coding (AMC and Incremental Redundancy Hybrid Automatic Repeat Request (IR-HARQ for MIMO

    Directory of Open Access Journals (Sweden)

    J. Sofia Priya Dharshini

    2014-09-01

    Full Text Available In MIMO Technology, a cross layer design enhances the spectral efficiency, reliability and throughput of the network. In this paper, a cross-layer approach using k-NN based Adaptive Modulation Coding (AMC and Incremental Redundancy Hybrid Automatic Repeat Request (IR-HARQ is proposed for MIMO Systems. The proposed cross layer approach connects physical layer and data link layer to enhance the performance of MIMO network. By means of MIMO fading channels, the coded symbols are forwarded in the physical layer on a frame by frame fashion subsequently using Space Time Block Coding (STBC. The receiver computes the signal to noise ratio (SNR and forwards back to the AMC controller. The controller selects a suitable MCS for the next transmission through k-NN classifier supervised learning algorithm. IR-HARQ is utilized at the data link layer to regulate packet retransmissions. The obtained results prove that the proposed technique has better performance in terms of throughput, BER and spectral efficiency

  19. Coded Adaptive Linear Precoded Discrete Multitone Over PLC Channel

    CERN Document Server

    Muhammad, Fahad Syed; Hélard, Jean-François; Crussière, Matthieu

    2008-01-01

    Discrete multitone modulation (DMT) systems exploit the capabilities of orthogonal subcarriers to cope efficiently with narrowband interference, high frequency attenuations and multipath fadings with the help of simple equalization filters. Adaptive linear precoded discrete multitone (LP-DMT) system is based on classical DMT, combined with a linear precoding component. In this paper, we investigate the bit and energy allocation algorithm of an adaptive LP-DMT system taking into account the channel coding scheme. A coded adaptive LPDMT system is presented in the power line communication (PLC) context with a loading algorithm which accommodates the channel coding gains in bit and energy calculations. The performance of a concatenated channel coding scheme, consisting of an inner Wei's 4-dimensional 16-states trellis code and an outer Reed-Solomon code, in combination with the proposed algorithm is analyzed. Theoretical coding gains are derived and simulation results are presented for a fixed target bit error ra...

  20. Relational Information Gain

    DEFF Research Database (Denmark)

    Lippi, Marco; Jaeger, Manfred; Frasconi, Paolo;

    2011-01-01

    We introduce relational information gain, a refinement scoring function measuring the informativeness of newly introduced variables. The gain can be interpreted as a conditional entropy in a well-defined sense and can be efficiently approximately computed. In conjunction with simple greedy general......-to-specific search algorithms such as FOIL, it yields an efficient and competitive algorithm in terms of predictive accuracy and compactness of the learned theory. In conjunction with the decision tree learner TILDE, it offers a beneficial alternative to lookahead, achieving similar performance while significantly...

  1. Gain control mechanisms in spinal motoneurons

    Directory of Open Access Journals (Sweden)

    Michael David Johnson

    2014-07-01

    Full Text Available Motoneurons provide the only conduit for motor commands to reach muscles. For many years, motoneurons were in fact considered to be little more than passive wires. Systematic studies in the past 25 years however have clearly demonstrated that the intrinsic electrical properties of motoneurons are under strong neuromodulatory control via multiple sources. The discovery of potent neuromodulation from the brainstem and its ability to change the gain of motoneurons shows that the passive view of the motor output stage is no longer tenable. A mechanism for gain control at the motor output stage makes good functional sense considering our capability of generating an enormous range of forces, from very delicate (e.g. putting in a contact lens to highly forceful (emergency reactions. Just as sensory systems need gain control to deal with a wide dynamic range of inputs, so to might motor output need gain control to deal with the wide dynamic range of the normal movement repertoire. Two problems emerge from the potential use of the brainstem monoaminergic projection to motoneurons for gain control. First, the projection is highly diffuse anatomically, so that independent control of the gains of different motor pools is not feasible. In fact, the system is so diffuse that gain for all the motor pools in a limb likely increases in concert. Second, if there is a system that increases gain, probably a system to reduce gain is also needed. In this review, we summarize recent studies that show local inhibitory circuits within the spinal cord, especially reciprocal and recurrent inhibition, have the potential to solve both of these problems as well as constitute another source of gain modulation.

  2. Gain lever characterization in monolithically integrated diode lasers

    Science.gov (United States)

    Pocha, Michael; Bond, Tiziana; Welty, Rebecca; Vernon, Stephen; Kallman, Jeffrey; Behymer, Elaine

    2005-04-01

    Gain Lever, an effect for enhancing amplitude modulation (AM) efficiency in multisection laser diodes1, has been characterized in InGaAs DQW edge emitting lasers that are integrated with passive waveguides. Specifically designed structures which give a range of split ratios from 1:1 to 9:1 have been fabricated and measured to fully characterize the parameter space for operation in the gain lever mode. Additionally the experimental results are compared to a hybrid 3-D simulation involving effective index method (EIM) reduction to 2-D. Gains greater than 6 dB in the AM efficiency can be achieved within the appropriate operating range, but this gain drops rapidly as the parameter range is exceeded. High speed RF modulation with significant gain is, in principle, possible if proper biasing and modulation conditions are used. This phenomenon can also be useful for high-speed digital information transmission.

  3. The influence of gain nonlinearities on distortion in semiconductor lasers

    Science.gov (United States)

    Lysak, Vladimir V.; Schatz, Richard; Shulika, Aleksey V.; Sukhoivanov, Igor A.; Kjebon, O.

    2004-09-01

    The semiconductor laser is commonly used as a light source in fiber-optical telecommunication systems. In order to send as much information as possible in a short time, it is important that the laser has a large modulation bandwidth, i.e., the turn-on and turn-off time should be as short as possible. In analogue fiber optic systems for transmission of radio or television signals, it is also important that the light from the laser increases linearly with driving current even at high modulation frequencies. Otherwise, the transmitted signal will become distorted. The modulation bandwidth and the modulation distortion are dependent both on the laser structure and the gain characteristics of the active material. One of the most useful approaches for the time-domain description of the response of optoelectronic devices is the so-called "rate equation model," which has been widely used to describe laser performance. Commonly, laser models with simple gain expressions are used for simulation of laser dynamics. In these models the small-signal dynamic parameters like the differential gain and gain saturation parameter are extracted from modulation response measurements. However, we show that in order to correctly calculate distortion, an accurate model of the dependence of gain on carrier density, n, and photon density, s, is needed. Commonly used gain models, fitted to give exactly the same modulation response can give significantly different distortion behavior.

  4. A Fast and Robust Method for Measuring Optical Channel Gain

    DEFF Research Database (Denmark)

    Harbo, Anders La-Cour; Stoustrup, Jakob; Villemoes, L.F.

    2000-01-01

    We present a numerically stable and computational simple method for fast and robust measurement of optical channel gain. By transmitting adaptively designed signals through the channel, good accuracy is possible even in severe noise conditions......We present a numerically stable and computational simple method for fast and robust measurement of optical channel gain. By transmitting adaptively designed signals through the channel, good accuracy is possible even in severe noise conditions...

  5. Adaptive optical interconnects: the ADDAPT project

    Science.gov (United States)

    Henker, Ronny; Pliva, Jan; Khafaji, Mahdi; Ellinger, Frank; Toifl, Thomas; Offrein, Bert; Cevrero, Alessandro; Oezkaya, Ilter; Seifried, Marc; Ledentsov, Nikolay; Kropp, Joerg-R.; Shchukin, Vitaly; Zoldak, Martin; Halmo, Leos; Turkiewicz, Jaroslaw; Meredith, Wyn; Eddie, Iain; Georgiades, Michael; Charalambides, Savvas; Duis, Jeroen; van Leeuwen, Pieter

    2015-09-01

    Existing optical networks are driven by dynamic user and application demands but operate statically at their maximum performance. Thus, optical links do not offer much adaptability and are not very energy-efficient. In this paper a novel approach of implementing performance and power adaptivity from system down to optical device, electrical circuit and transistor level is proposed. Depending on the actual data load, the number of activated link paths and individual device parameters like bandwidth, clock rate, modulation format and gain are adapted to enable lowering the components supply power. This enables flexible energy-efficient optical transmission links which pave the way for massive reductions of CO2 emission and operating costs in data center and high performance computing applications. Within the FP7 research project Adaptive Data and Power Aware Transceivers for Optical Communications (ADDAPT) dynamic high-speed energy-efficient transceiver subsystems are developed for short-range optical interconnects taking up new adaptive technologies and methods. The research of eight partners from industry, research and education spanning seven European countries includes the investigation of several adaptive control types and algorithms, the development of a full transceiver system, the design and fabrication of optical components and integrated circuits as well as the development of high-speed, low loss packaging solutions. This paper describes and discusses the idea of ADDAPT and provides an overview about the latest research results in this field.

  6. Rate and Power Allocation for Discrete-Rate Link Adaptation

    CERN Document Server

    Gjendemsjø, Anders; Holm, Henrik; Alouini, Mohamed-Slim; Gesbert, David; Hole, Kjell J; Orten, Pål

    2007-01-01

    Link adaptation, in particular adaptive coded modulation (ACM), is a promising tool for bandwidth-efficient transmission in a fading environment. The main motivation behind employing ACM schemes is to improve the spectral efficiency of wireless communication systems. In this paper, using a finite number of capacity achieving component codes, we propose new transmission schemes employing constant power transmission, as well as discrete and continuous power adaptation, for slowly varying flat-fading channels. We show that the proposed transmission schemes can achieve throughputs close to the Shannon limits of flat-fading channels using only a small number of codes. Specifically, using a fully discrete scheme with just four codes, each associated with four power levels, we achieve a spectral efficiency within 1 dB of the continuous-rate continuous-power Shannon capacity. Furthermore, when restricted to a fixed number of codes, the introduction of power adaptation has significant gains with respect to ASE and pro...

  7. Topological light bullets supported by spatio-temporal gain

    CERN Document Server

    Lobanov, Valery E; Kartashov, Yaroslav V; Vysloukh, Victor A; Torner, Lluis

    2012-01-01

    We reveal that the competition between diffraction, cubic nonlinearity, two-photon absorption, and gain localized in both space and time results in arrest of collapse, suppression of azimuthal modula-tion instabilities for spatiotemporal wavepackets, and formation of stable three-dimensional light bul-lets. We show that Gaussian spatiotemporal gain landscapes support bright, fundamental light bullets, while gain landscapes featuring a ring-like spatial and a Gaussian temporal shapes may support stable vortex bullets carrying topological phase dislocations.

  8. Gaining Relational Competitive Advantages

    DEFF Research Database (Denmark)

    Hu, Yimei; Zhang, Si; Li, Jizhen;

    2015-01-01

    Establishing strategic technological partnerships (STPs) with foreign partners is an increasingly studied topic within the innovation management literature. Partnering firms can jointly create sources of relational competitive advantage. Chinese firms often lack research and development (R......&D) capabilities but are increasingly becoming preferred technological partners for transnational corporations. We investigate an STP between a Scandinavian and a Chinese firm and try to explore how to gain relational competitive advantage by focusing on its two essential stages: relational rent generation...... and appropriation. Based on an explorative case study, we develop a conceptual framework that consists of process, organizational alliance factors, and coordination modes that we propose lead to relational competitive advantage....

  9. Carbohydrate modified diet & insulin sensitizers reduce body weight & modulate metabolic syndrome measures in EMPOWIR (enhance the metabolic profile of women with insulin resistance: a randomized trial of normoglycemic women with midlife weight gain.

    Directory of Open Access Journals (Sweden)

    Harriette R Mogul

    Full Text Available RATIONALE: Progressive midlife weight gain is associated with multiple adverse health outcomes and may represent an early manifestation of insulin resistance in a distinct subset of women. Emerging data implicate hyperinsulinema as a proximate cause of weight gain and support strategies that attenuate insulin secretion. OBJECTIVE: To assess a previously reported novel hypocaloric carbohydrate modified diet alone (D, and in combination with metformin (M and metformin plus low-dose rosiglitazone (MR, in diverse women with midlife weight gain (defined as >20lbs since the twenties, normal glucose tolerance, and hyperinsulinemia. PARTICIPANTS: 46 women, mean age 46.6±1.0, BMI 30.5±0.04 kg/m2, 54.5% white, 22.7% black, 15.9% Hispanic, at 2 university medical centers. METHODS: A dietary intervention designed to reduce insulin excursions was implemented in 4 weekly nutritional group workshops prior to randomization. MAIN OUTCOME MEASURE: Change in 6-month fasting insulin. Pre-specified secondary outcomes were changes in body weight, HOMA-IR, metabolic syndrome (MS measures, leptin, and adiponectin. RESULTS: Six-month fasting insulin declined significantly in the M group: 12.5 to 8.0 µU/ml, p = .026. Mean 6-month weight decreased significantly and comparably in D, M, and MR groups: 4.7, 5.4, and 5.5% (p's.049, .002, and.032. HOMA-IR decreased in M and MR groups (2.5 to 1.6 and 1.9 to 1.3, p's = .054, .013. Additional improvement in MS measures included reduced waist circumference in D and MR groups and increased HDL in the D and M groups. Notably, mean fasting leptin did not decline in a subset of subjects with weight loss (26.15±2.01 ng/ml to 25.99±2.61 ng/ml, p = .907. Adiponectin increased significantly in the MR group (11.1±1.0 to 18.5±7.4, p<.001 Study medications were well tolerated. CONCLUSIONS: These findings suggest that EMPOWIR's easily implemented dietary interventions, alone and in combination with pharmacotherapies that

  10. Remote Sensing Image Fusion Using Multi-scale Spectrum Gain Modulation%基于多尺度光谱增益调制的遥感影像融合方法

    Institute of Scientific and Technical Information of China (English)

    刘军; 邵振峰

    2011-01-01

    When the classic methods,such as IHS(intensity-hue-saturation) transform,PCA(principal component analysis) transform,etc.,are employed in image fusion,the color distortion problem will appear due to the change of saturation.To solve this problem,a multi scale spectrum gain modulation(SGM) image fusion method is proposed,which is based on the spectrum gain surface(SGS) and can reduce the color distortion relating to the change of saturation,so as to preserve the spectrum.The experimental results and objective evaluations indicate that,compared to the conventional image fusion methods(IHS,PCA,etc.),the proposed method can obtain the better tradeoff between improving the spatial resolution and preserving the spectral characteristics.%针对IHS和PCA等常用影像融合方法会产生较严重的光谱扭曲的问题,基于光谱增益曲面,提出一种多尺度光谱增益调制的光谱保持型遥感影像融合方法,能够有效地减少由于饱和度变化而引起的光谱扭曲。融合试验和客观评价指标证明,与传统的IHS、PCA等方法相比,本文方法能够在提高空间分辨率和保持光谱特征之间取得更好的平衡。

  11. Sudden gains in psychotherapy

    OpenAIRE

    Auður Sjöfn Þórisdóttir 1986

    2014-01-01

    Verkefni þetta samanstendur af fræðilegu yfirliti og rannsóknagrein til birtingar í vísindatímarit. Verkefnið fjallar um tiltekið mynstur breytinga á einkennum geðraskana í sálfræðimeðferð, sem kallast skyndiframfarir (e. sudden gains) og þekkist af skyndilegum og miklum breytingum á einkennum milli tveggja meðferðartíma. Í fræðilega yfirlitinu er farið yfir hvernig þetta breytingamynstur hefur verið skilgreint og skýrt og sagt frá helstu niðurstöðum rannsókna á þessu sviði. Fjallað er um ann...

  12. Change, Gain and Loss

    Institute of Scientific and Technical Information of China (English)

    Fu Mengzi

    2006-01-01

    @@ Five years have passed since the September 11 terrorist attacks occurred. America's counter-terrorism campaign is still on the way.Besides the momentary monumental significance of the fifth anniversary, five years is still too short in regard to the long-term counter-terrorism campaign. Yet, America's president's tenure is eight years at best; most of Bush's presidency time has passed. Five years ago, the U. S. encountered the most serious terrorist attack; the whole nation formed a consensus that counter-terrorism is its utmost priority. President Bush once enjoyed a support rate as high as 90% for over 16 months. But five years later, the trend changes. People can not help but ask: what are the gains and losses of the Republican Party in dealing with national security affairs?

  13. Ballasted photovoltaic module and module arrays

    Science.gov (United States)

    Botkin, Jonathan; Graves, Simon; Danning, Matt

    2011-11-29

    A photovoltaic (PV) module assembly including a PV module and a ballast tray. The PV module includes a PV device and a frame. A PV laminate is assembled to the frame, and the frame includes an arm. The ballast tray is adapted for containing ballast and is removably associated with the PV module in a ballasting state where the tray is vertically under the PV laminate and vertically over the arm to impede overt displacement of the PV module. The PV module assembly can be installed to a flat commercial rooftop, with the PV module and the ballast tray both resting upon the rooftop. In some embodiments, the ballasting state includes corresponding surfaces of the arm and the tray being spaced from one another under normal (low or no wind) conditions, such that the frame is not continuously subjected to a weight of the tray.

  14. Gain Efficient L-band EDFA With Dynamic Gain Equalization

    Institute of Scientific and Technical Information of China (English)

    Xiaoli Hui; Rujian Lin

    2003-01-01

    A gain efficient L-band erbium-doped fiber amplifier with dynamic gain equalization is presented. Using a single fiber Bragg grating and a static equalizer, the gain is clamped at 27dB with less than 0.5dB variations over 35nm.

  15. Dynamics of dual prism adaptation: relating novel experimental results to a minimalistic neural model.

    Directory of Open Access Journals (Sweden)

    Orlando Arévalo

    Full Text Available In everyday life, humans interact with a dynamic environment often requiring rapid adaptation of visual perception and motor control. In particular, new visuo-motor mappings must be learned while old skills have to be kept, such that after adaptation, subjects may be able to quickly change between two different modes of generating movements ('dual-adaptation'. A fundamental question is how the adaptation schedule determines the acquisition speed of new skills. Given a fixed number of movements in two different environments, will dual-adaptation be faster if switches ('phase changes' between the environments occur more frequently? We investigated the dynamics of dual-adaptation under different training schedules in a virtual pointing experiment. Surprisingly, we found that acquisition speed of dual visuo-motor mappings in a pointing task is largely independent of the number of phase changes. Next, we studied the neuronal mechanisms underlying this result and other key phenomena of dual-adaptation by relating model simulations to experimental data. We propose a simple and yet biologically plausible neural model consisting of a spatial mapping from an input layer to a pointing angle which is subjected to a global gain modulation. Adaptation is performed by reinforcement learning on the model parameters. Despite its simplicity, the model provides a unifying account for a broad range of experimental data: It quantitatively reproduced the learning rates in dual-adaptation experiments for both direct effect, i.e. adaptation to prisms, and aftereffect, i.e. behavior after removal of prisms, and their independence on the number of phase changes. Several other phenomena, e.g. initial pointing errors that are far smaller than the induced optical shift, were also captured. Moreover, the underlying mechanisms, a local adaptation of a spatial mapping and a global adaptation of a gain factor, explained asymmetric spatial transfer and generalization of prism

  16. Development of the Digital Astronaut Project for the analysis of the mechanisms of physiologic adaptation to microgravity: Validation of the cardiovascular system module

    Science.gov (United States)

    Summers, Richard; Coleman, Thomas; Meck, Janice

    The physiologic adaptation of humans to the microgravity environment is complex and requires an integrative perspective to fully understand the mechanisms involved. A large computer model of human systems physiology provides the framework for the development of the Digital Astronaut to be used by NASA in the analysis of adaptive mechanisms. While project expansion is ongoing to include all relevant systems, we describe the validation results of the cardiovascular phase of model development. The cardiovascular aspects of the model were validated by benchmark comparisons to published literature findings of changes in left ventricular mass, right atrial pressure and plasma volumes. Computer simulations using the model predicted microgravity induced changes in the target endpoints within statistical validity of experimental findings. Therefore, the current cardiovascular portion of the Digital Astronaut Project computer model appears to accurately predict observed microgravity induced physiologic adaptations. The ongoing process of model development to include all spaceflight relevant systems will require similar validations.

  17. Gain Flattening Filter Canceling Temperature Dependence of EDFA s gain

    Institute of Scientific and Technical Information of China (English)

    M.; Ohmura; Y.; Ishizawa; H.; Nakaji; K.; Hashimoto; T.; Shibata; M.; Shigehara; A.; Inoue

    2003-01-01

    We have developed a gain flattening filter (GFF) for an erbium doped fiber (EDF) without temperature control systems. This GFF, which consists of temperature-sensitive long period gratings (LPGs) and a temperature compensated slanted fiber Bragg grating (SFBG), follows the gain shift of EDF with temperature. Gain variation of the EDFA less than 0.25dBp-p was achieved with the bandwidth of 37nm, and the temperature range 0-65℃ without any temperature control systems.

  18. Adaptive high-gain extended kalman filter and applications

    OpenAIRE

    Boizot, Nicolas Richard

    2010-01-01

    The work concerns the ``observability problem” --- the reconstruction of a dynamic process's full state from a partially measured state--- for nonlinear dynamic systems. The Extended Kalman Filter (EKF) is a widely-used observer for such nonlinear systems. However it suffers from a lack of theoretical justifications and displays poor performance when the estimated state is far from the real state, e.g. due to large perturbations, a poor initial state estimate, etc… We propose a solution to...

  19. Photovoltaic module and module arrays

    Science.gov (United States)

    Botkin, Jonathan; Graves, Simon; Lenox, Carl J. S.; Culligan, Matthew; Danning, Matt

    2012-07-17

    A photovoltaic (PV) module including a PV device and a frame. The PV device has a PV laminate defining a perimeter and a major plane. The frame is assembled to and encases the laminate perimeter, and includes leading, trailing, and side frame members, and an arm that forms a support face opposite the laminate. The support face is adapted for placement against a horizontal installation surface, to support and orient the laminate in a non-parallel or tilted arrangement. Upon final assembly, the laminate and the frame combine to define a unitary structure. The frame can orient the laminate at an angle in the range of 3.degree.-7.degree. from horizontal, and can be entirely formed of a polymeric material. Optionally, the arm incorporates integral feature(s) that facilitate interconnection with corresponding features of a second, identically formed PV module.

  20. Advanced Adaptive Optics Technology Development

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, S

    2001-09-18

    The NSF Center for Adaptive Optics (CfAO) is supporting research on advanced adaptive optics technologies. CfAO research activities include development and characterization of micro-electro-mechanical systems (MEMS) deformable mirror (DM) technology, as well as development and characterization of high-resolution adaptive optics systems using liquid crystal (LC) spatial light modulator (SLM) technology. This paper presents an overview of the CfAO advanced adaptive optics technology development activities including current status and future plans.

  1. Gains of ubiquitylation sites in highly conserved proteins in the human lineage

    Directory of Open Access Journals (Sweden)

    Kim Dong Seon

    2012-11-01

    Full Text Available Abstract Background Post-translational modification of lysine residues of specific proteins by ubiquitin modulates the degradation, localization, and activity of these target proteins. Here, we identified gains of ubiquitylation sites in highly conserved regions of human proteins that occurred during human evolution. Results We analyzed human ubiquitylation site data and multiple alignments of orthologous mammalian proteins including those from humans, primates, other placental mammals, opossum, and platypus. In our analysis, we identified 281 ubiquitylation sites in 252 proteins that first appeared along the human lineage during primate evolution: one protein had four novel sites; four proteins had three sites each; 18 proteins had two sites each; and the remaining 229 proteins had one site each. PML, which is involved in neurodevelopment and neurodegeneration, acquired three sites, two of which have been reported to be involved in the degradation of PML. Thirteen human proteins, including ERCC2 (also known as XPD and NBR1, gained human-specific ubiquitylated lysines after the human-chimpanzee divergence. ERCC2 has a Lys/Gln polymorphism, the derived (major allele of which confers enhanced DNA repair capacity and reduced cancer risk compared with the ancestral (minor allele. NBR1 and eight other proteins that are involved in the human autophagy protein interaction network gained a novel ubiquitylation site. Conclusions The gain of novel ubiquitylation sites could be involved in the evolution of protein degradation and other regulatory networks. Although gains of ubiquitylation sites do not necessarily equate to adaptive evolution, they are useful candidates for molecular functional analyses to identify novel advantageous genetic modifications and innovative phenotypes acquired during human evolution.

  2. A Semantic-Oriented Architecture of a Functional Module for Personalized and Adaptive Access to the Knowledge in a Multimedia Digital Library

    OpenAIRE

    Paneva-Marinova, Desislava

    2008-01-01

    This article presents the principal results of the doctoral thesis “Semantic-oriented Architecture and Models for Personalized and Adaptive Access to the Knowledge in Multimedia Digital Library” by Desislava Ivanova Paneva-Marinova (Institute of Mathematics and Informatics), successfully defended before the Specialised Academic Council for Informatics and Mathematical Modelling on 27 October, 2008. This paper presents dissertation work on semantic-oriented architectures and...

  3. Dosimetric consequences of tumor volume changes after kilovoltage cone-beam computed tomography for non-operative lung cancer during adaptive intensity-modulated radiotherapy or fractionated stereotactic radiotherapy

    Institute of Scientific and Technical Information of China (English)

    Jian Hu; Ximing Xu; Guangjin Yuan; Wei Ge; Liming Xu; Aihua Zhang; Junjian Deng

    2015-01-01

    Objective The aim of this study was to investigate tumor volume changes with kilovoltage cone-beam computed tomography (kV-CBCT) and their dosimetric consequences for non-operative lung cancer during intensity-modulated radiotherapy (IMRT) or fractionated stereotactic radiotherapy. Methods Eighteen patients with non-operative lung cancer who received IMRT consisting of 1.8-2.2 Gy/fraction and five fractions per week or stereotactic radiotherapy with 5-8 Gy/fraction and three fractions a week were studied. kV-CBCT was performed once per week during IMRT and at every fraction during stereotactic radiotherapy. The gross tumor volume (GTV) was contoured on the kV-CBCT images, and adaptive treatment plans were created using merged kV-CBCT and primary planning computed tomogra-phy image sets. Tumor volume changes and dosimetric parameters, including the minimum dose to 95%(D95) or 1% (D1) of the planning target volume (PTV), mean lung dose (MLD), and volume of lung tissue that received more than 5 (V5), 10 (V10), 20 (V20), and 30 (V30) Gy were retrospectively analyzed. Results The average maximum change in GTV observed during IMRT or fractionated stereotactic radio-therapy was -25.85% (range, -13.09% --56.76%). The D95 and D1 of PTV for the adaptive treatment plans in all patients were not significantly different from those for the initial or former adaptive treatment plans. In patients with tumor volume changes of >20% in the third or fourth week of treatment during IMRT, adap-tive treatment plans offered clinically meaningful decreases in MLD and V5, V10, V20, and V30; however, in patients with tumor volume changes of 20% in the third or fourth week of treatment.

  4. Individualized Nonadaptive and Online-Adaptive Intensity-Modulated Radiotherapy Treatment Strategies for Cervical Cancer Patients Based on Pretreatment Acquired Variable Bladder Filling Computed Tomography Scans

    Energy Technology Data Exchange (ETDEWEB)

    Bondar, M.L., E-mail: m.bondar@erasmusmc.nl [Department of Radiation Oncology, Erasmus-MC Daniel den Hoed Cancer Center, Rotterdam (Netherlands); Hoogeman, M.S.; Mens, J.W.; Quint, S. [Department of Radiation Oncology, Erasmus-MC Daniel den Hoed Cancer Center, Rotterdam (Netherlands); Ahmad, R. [Department of Radiation Oncology, Erasmus-MC Daniel den Hoed Cancer Center, Rotterdam (Netherlands); Programme of Diagnostic Imaging and Radiotherapy, University Kebangsaan Malaysia (Malaysia); Dhawtal, G.; Heijmen, B.J. [Department of Radiation Oncology, Erasmus-MC Daniel den Hoed Cancer Center, Rotterdam (Netherlands)

    2012-08-01

    Purpose: To design and evaluate individualized nonadaptive and online-adaptive strategies based on a pretreatment established motion model for the highly deformable target volume in cervical cancer patients. Methods and Materials: For 14 patients, nine to ten variable bladder filling computed tomography (CT) scans were acquired at pretreatment and after 40 Gy. Individualized model-based internal target volumes (mbITVs) accounting for the cervix and uterus motion due to bladder volume changes were generated by using a motion-model constructed from two pretreatment CT scans (full and empty bladder). Two individualized strategies were designed: a nonadaptive strategy, using an mbITV accounting for the full-range of bladder volume changes throughout the treatment; and an online-adaptive strategy, using mbITVs of bladder volume subranges to construct a library of plans. The latter adapts the treatment online by selecting the plan-of-the-day from the library based on the measured bladder volume. The individualized strategies were evaluated by the seven to eight CT scans not used for mbITVs construction, and compared with a population-based approach. Geometric uniform margins around planning cervix-uterus and mbITVs were determined to ensure adequate coverage. For each strategy, the percentage of the cervix-uterus, bladder, and rectum volumes inside the planning target volume (PTV), and the clinical target volume (CTV)-to-PTV volume (volume difference between PTV and CTV) were calculated. Results: The margin for the population-based approach was 38 mm and for the individualized strategies was 7 to 10 mm. Compared with the population-based approach, the individualized nonadaptive strategy decreased the CTV-to-PTV volume by 48% {+-} 6% and the percentage of bladder and rectum inside the PTV by 5% to 45% and 26% to 74% (p < 0.001), respectively. Replacing the individualized nonadaptive strategy by an online-adaptive, two-plan library further decreased the percentage of

  5. Gain Flattening Filter Canceling Temperature Dependence of EDFA's gain

    Institute of Scientific and Technical Information of China (English)

    M. Ohmura; Y. Ishizawa; H. Nakaji; K. Hashimoto; T. Shibata; M. Shigehara; A. Inoue

    2003-01-01

    We have developed a gain flattening filter(GFF) for an erbium doped fiber (EDF) without temperature control systems. This GFF, which consists of temperature-sensitive long period gratings (LPGs)and a temperature compensated slanted fiber Bragg grating (SFBG), follows the gain shift of EDF with temperature. Gain variation of the EDFA less than 0.25dBp-p was achieved with the bandwidth of 37nm,and the temperature range 0-65℃ without and temperature control systems.

  6. Appraising Adaptive Management

    Directory of Open Access Journals (Sweden)

    Kai N. Lee

    1999-12-01

    Full Text Available Adaptive management is appraised as a policy implementation approach by examining its conceptual, technical, equity, and practical strengths and limitations. Three conclusions are drawn: (1 Adaptive management has been more influential, so far, as an idea than as a practical means of gaining insight into the behavior of ecosystems utilized and inhabited by humans. (2 Adaptive management should be used only after disputing parties have agreed to an agenda of questions to be answered using the adaptive approach; this is not how the approach has been used. (3 Efficient, effective social learning, of the kind facilitated by adaptive management, is likely to be of strategic importance in governing ecosystems as humanity searches for a sustainable economy.

  7. First Clinical Release of an Online, Adaptive, Aperture-Based Image-Guided Radiotherapy Strategy in Intensity-Modulated Radiotherapy to Correct for Inter- and Intrafractional Rotations of the Prostate

    Energy Technology Data Exchange (ETDEWEB)

    Deutschmann, Heinz, E-mail: h.deutschmann@salk.at [University Clinic for Radiotherapy and Radio-Oncology, Salzburg (Austria); radART Institute for Research and Development of Advanced Radiation Technologies, Paracelsus Medical University, Salzburg (Austria); Kametriser, Gerhard [University Clinic for Radiotherapy and Radio-Oncology, Salzburg (Austria); Steininger, Philipp [radART Institute for Research and Development of Advanced Radiation Technologies, Paracelsus Medical University, Salzburg (Austria); Scherer, Philipp; Schoeller, Helmut [University Clinic for Radiotherapy and Radio-Oncology, Salzburg (Austria); Gaisberger, Christoph [University Clinic for Radiotherapy and Radio-Oncology, Salzburg (Austria); radART Institute for Research and Development of Advanced Radiation Technologies, Paracelsus Medical University, Salzburg (Austria); Mooslechner, Michaela [radART Institute for Research and Development of Advanced Radiation Technologies, Paracelsus Medical University, Salzburg (Austria); Mitterlechner, Bernhard; Weichenberger, Harald [University Clinic for Radiotherapy and Radio-Oncology, Salzburg (Austria); radART Institute for Research and Development of Advanced Radiation Technologies, Paracelsus Medical University, Salzburg (Austria); Fastner, Gert; Wurstbauer, Karl [University Clinic for Radiotherapy and Radio-Oncology, Salzburg (Austria); Jeschke, Stephan [University Clinic for Urology and Andrology, Salzburg (Austria); Forstner, Rosemarie [University Clinic for Radiology, Salzburg (Austria); Sedlmayer, Felix [University Clinic for Radiotherapy and Radio-Oncology, Salzburg (Austria); radART Institute for Research and Development of Advanced Radiation Technologies, Paracelsus Medical University, Salzburg (Austria)

    2012-08-01

    Purpose: We developed and evaluated a correction strategy for prostate rotations using direct adaptation of segments in intensity-modulated radiotherapy (IMRT). Method and Materials: Implanted fiducials (four gold markers) were used to determine interfractional translations, rotations, and dilations of the prostate. We used hybrid imaging: The markers were automatically detected in two pretreatment planar X-ray projections; their actual position in three-dimensional space was reconstructed from these images at first. The structure set comprising prostate, seminal vesicles, and adjacent rectum wall was transformed accordingly in 6 degrees of freedom. Shapes of IMRT segments were geometrically adapted in a class solution forward-planning approach, derived within seconds on-site and treated immediately. Intrafractional movements were followed in MV electronic portal images captured on the fly. Results: In 31 of 39 patients, for 833 of 1013 fractions (supine, flat couch, knee support, comfortably full bladder, empty rectum, no intraprostatic marker migrations >2 mm of more than one marker), the online aperture adaptation allowed safe reduction of margins clinical target volume-planning target volume (prostate) down to 5 mm when only interfractional corrections were applied: Dominant L-R rotations were found to be 5.3 Degree-Sign (mean of means), standard deviation of means {+-}4.9 Degree-Sign , maximum at 30.7 Degree-Sign . Three-dimensional vector translations relative to skin markings were 9.3 {+-} 4.4 mm (maximum, 23.6 mm). Intrafractional movements in 7.7 {+-} 1.5 min (maximum, 15.1 min) between kV imaging and last beam's electronic portal images showed further L-R rotations of 2.5 Degree-Sign {+-} 2.3 Degree-Sign (maximum, 26.9 Degree-Sign ), and three-dimensional vector translations of 3.0 {+-}3.7 mm (maximum, 10.2 mm). Addressing intrafractional errors could further reduce margins to 3 mm. Conclusion: We demonstrated the clinical feasibility of an online

  8. First Clinical Release of an Online, Adaptive, Aperture-Based Image-Guided Radiotherapy Strategy in Intensity-Modulated Radiotherapy to Correct for Inter- and Intrafractional Rotations of the Prostate

    International Nuclear Information System (INIS)

    Purpose: We developed and evaluated a correction strategy for prostate rotations using direct adaptation of segments in intensity-modulated radiotherapy (IMRT). Method and Materials: Implanted fiducials (four gold markers) were used to determine interfractional translations, rotations, and dilations of the prostate. We used hybrid imaging: The markers were automatically detected in two pretreatment planar X-ray projections; their actual position in three-dimensional space was reconstructed from these images at first. The structure set comprising prostate, seminal vesicles, and adjacent rectum wall was transformed accordingly in 6 degrees of freedom. Shapes of IMRT segments were geometrically adapted in a class solution forward-planning approach, derived within seconds on-site and treated immediately. Intrafractional movements were followed in MV electronic portal images captured on the fly. Results: In 31 of 39 patients, for 833 of 1013 fractions (supine, flat couch, knee support, comfortably full bladder, empty rectum, no intraprostatic marker migrations >2 mm of more than one marker), the online aperture adaptation allowed safe reduction of margins clinical target volume–planning target volume (prostate) down to 5 mm when only interfractional corrections were applied: Dominant L-R rotations were found to be 5.3° (mean of means), standard deviation of means ±4.9°, maximum at 30.7°. Three-dimensional vector translations relative to skin markings were 9.3 ± 4.4 mm (maximum, 23.6 mm). Intrafractional movements in 7.7 ± 1.5 min (maximum, 15.1 min) between kV imaging and last beam’s electronic portal images showed further L-R rotations of 2.5° ± 2.3° (maximum, 26.9°), and three-dimensional vector translations of 3.0 ±3.7 mm (maximum, 10.2 mm). Addressing intrafractional errors could further reduce margins to 3 mm. Conclusion: We demonstrated the clinical feasibility of an online adaptive image-guided, intensity-modulated prostate protocol on a standard

  9. Divisive gain modulation of motoneurons by inhibition optimizes muscular control

    DEFF Research Database (Denmark)

    Vestergaard, Mikkel; Berg, Rune W.

    2015-01-01

    When using muscles, the precision with which force is delivered is as important as the delivery of force itself. Force is regulated by both the number of recruited motoneurons and their spike frequency. While it is known that the recruitment is ordered to reduce variability in force, it remains u...

  10. LEARNING SCHEDULER PARAMETERS FOR ADAPTIVE PREEMPTION

    Directory of Open Access Journals (Sweden)

    Prakhar Ojha

    2015-11-01

    Full Text Available An operating system scheduler is expected to not allow processor stay idle if there is any process ready or waiting for its execution. This problem gains more importance as the numbers of processes always outnumber the processors by large margins. It is in this regard that schedulers are provided with the ability to preempt a running process, by following any scheduling algorithm, and give us an illusion of simultaneous running of several processes. A process which is allowed to utilize CPU resources for a fixed quantum of time (termed as timeslice for preemption and is then preempted for another waiting process. Each of these 'process preemption' leads to considerable overhead of CPU cycles which are valuable resource for runtime execution. In this work we try to utilize the historical performances of a scheduler and predict the nature of current running process, thereby trying to reduce the number of preemptions. We propose a machine-learning module to predict a better performing timeslice which is calculated based on static knowledge base and adaptive reinforcement learning based suggestive module. Results for an "adaptive timeslice parameter" for preemption show good saving on CPU cycles and efficient throughput time

  11. 利用自适应编码调制的无线网络控制系统的分析和设计%Analysis and Design of Wireless Networked Control System Utilizing Adaptive Coded Modulation

    Institute of Scientific and Technical Information of China (English)

    杨丽; 郑新平; 龙承念; 罗小元

    2009-01-01

    In this paper, we explore the analysis and design of wireless networked control system (WNCS) utilizing adaptive coded modulation (ACM) schemes, which can improve the energy efficiency and increase data rate over a fading channel. To capture the characteristics of varying rate, interference, and routing in wireless transmission channel, we introduce the concept of equivalent delay (ED). Based on the time-varying network condition, the analytic lower and upper bounds of EDs are given. Whereafter, WNCS is modelled as a discrete-time system with time-varying input delay. Sufficient stabilization condition of the closed-loop WNCS is derived by making use of novel techniques of time-delay system. Finally, the numerical result shows the validity of our proposed control strategies.

  12. Hypothalamic deep brain stimulation reduces weight gain in an obesity-animal model.

    Directory of Open Access Journals (Sweden)

    William P Melega

    Full Text Available Prior studies of appetite regulatory networks, primarily in rodents, have established that targeted electrical stimulation of ventromedial hypothalamus (VMH can alter food intake patterns and metabolic homeostasis. Consideration of this method for weight modulation in humans with severe overeating disorders and morbid obesity can be further advanced by modeling procedures and assessing endpoints that can provide preclinical data on efficacy and safety. In this study we adapted human deep brain stimulation (DBS stereotactic methods and instrumentation to demonstrate in a large animal model the modulation of weight gain with VMH-DBS. Female Göttingen minipigs were used because of their dietary habits, physiologic characteristics, and brain structures that resemble those of primates. Further, these animals become obese on extra-feeding regimens. DBS electrodes were first bilaterally implanted into the VMH of the animals (n = 8 which were then maintained on a restricted food regimen for 1 mo following the surgery. The daily amount of food was then doubled for the next 2 mo in all animals to produce obesity associated with extra calorie intake, with half of the animals (n = 4 concurrently receiving continuous low frequency (50 Hz VMH-DBS. Adverse motoric or behavioral effects were not observed subsequent to the surgical procedure or during the DBS period. Throughout this 2 mo DBS period, all animals consumed the doubled amount of daily food. However, the animals that had received VMH-DBS showed a cumulative weight gain (6.1±0.4 kg; mean ± SEM that was lower than the nonstimulated VMH-DBS animals (9.4±1.3 kg; p<0.05, suggestive of a DBS-associated increase in metabolic rate. These results in a porcine obesity model demonstrate the efficacy and behavioral safety of a low frequency VMH-DBS application as a potential clinical strategy for modulation of body weight.

  13. Heritability of gestational weight gain

    DEFF Research Database (Denmark)

    Andersson, Elina Scheers; Silventoinen, Karri; Tynelius, Per;

    2015-01-01

    Gestational weight gain (GWG) is a complex trait involving intrauterine environmental, maternal environmental, and genetic factors. However, the extent to which these factors contribute to the total variation in GWG is unclear. We therefore examined the genetic and environmental influences...

  14. Contribution of the modulation of intensity and the optimization to deliver a dose adapted to the biological heterogeneities; Apport de la modulation d'intensite et de l'optimisation pour delivrer une dose adaptee aux heterogeneites biologiques

    Energy Technology Data Exchange (ETDEWEB)

    Kubs, F

    2007-10-15

    The recent progress in functional imaging by Positron Emission Tomography (TEP) opens new perspectives in the delineation of target volumes in radiotherapy. The functional data is major; we can intend to adapt the irradiation doses on the tumor activity (TA) and to perform a dose escalation. Our objectives were (i) to characterize the TEP threshold, by quantifying the uncertainties of the target volume contour according to the lesion size and the threshold contour level, (ii) to set up the geometry suited to perform a high-precision irradiation based on the TA, (iii) to estimate the dosimetric impact of this new protocol and (iv) to verify that dosimetry is perfectly distributed. Three original phantoms were specially created to satisfy the constraints met, as well as two virtual phantoms containing 3 dose levels (dose level 3 = TA). Our results showed the importance of the effect threshold-volume on the planning in radiotherapy. To use this irradiation method, the diameter of 1 cm for the third level was able to be reached. A dose escalation of 20 Gy was possible between the second (70 Gy) and the third level (90 Gy). The dosimetric impact estimated on two real cases was suitable - increase of COIN (conformal index) from 0.6 to 0.8 and decrease of NTCP (normal tissue complication probability) of a factor 5 -. In absolute and relative dosimetry, the clinical tolerances were respected. So all the treatment process, going from the diagnosis with the TEP to reveal the TA, to the patient treatment made beforehand on phantom, and going through the ballistic and the dose calculation, was estimated and validated according to our objective to adapt the irradiation to the biological heterogeneities. However such high doses should be carefully estimated before being prescribed clinically and progress is also expected in imaging, because the minimal size which we can irradiate is on the limit of the resolution TEP. (author)

  15. Adaptive kernel density estimation

    OpenAIRE

    Philippe Van Kerm

    2003-01-01

    This insert describes the module akdensity. akdensity extends the official kdensity that estimates density functions by the kernel method. The extensions are of two types: akdensity allows the use of an "adaptive kernel" approach with varying, rather than fixed, bandwidths; and akdensity estimates pointwise variability bands around the estimated density functions. Copyright 2003 by Stata Corporation.

  16. Developmental gains in visuospatial memory predict gains in mathematics achievement.

    Science.gov (United States)

    Li, Yaoran; Geary, David C

    2013-01-01

    Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d = 2.4) were larger than gains in the capacity of the central executive (d = 1.6) that in turn were larger than gains in phonological memory span (d = 1.1). First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning.

  17. Developmental gains in visuospatial memory predict gains in mathematics achievement.

    Directory of Open Access Journals (Sweden)

    Yaoran Li

    Full Text Available Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d = 2.4 were larger than gains in the capacity of the central executive (d = 1.6 that in turn were larger than gains in phonological memory span (d = 1.1. First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning.

  18. Electrical and Optical Gain Lever Effects in InGaAs Double Quantum Well Diode Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Pocha, M D; Goddard, L L; Bond, T C; Nikolic, R J; Vernon, S P; Kallman, J S; Behymer, E M

    2007-01-03

    In multisection laser diodes, the amplitude or frequency modulation (AM or FM) efficiency can be improved using the gain lever effect. To study gain lever, InGaAs double quantum well (DQW) edge emitting lasers have been fabricated with integrated passive waveguides and dual sections providing a range of split ratios from 1:1 to 9:1. Both the electrical and the optical gain lever have been examined. An electrical gain lever with greater than 7 dB enhancement of AM efficiency was achieved within the range of appropriate DC biasing currents, but this gain dropped rapidly outside this range. We observed a 4 dB gain in the optical AM efficiency under non-ideal biasing conditions. This value agreed with the measured gain for the electrical AM efficiency under similar conditions. We also examined the gain lever effect under large signal modulation for digital logic switching applications. To get a useful gain lever for optical gain quenched logic, a long control section is needed to preserve the gain lever strength and a long interaction length between the input optical signal and the lasing field of the diode must be provided. The gain lever parameter space has been fully characterized and validated against numerical simulations of a semi-3D hybrid beam propagation method (BPM) model for the coupled electron-photon rate equation. We find that the optical gain lever can be treated using the electrical injection model, once the absorption in the sample is known.

  19. High current gain transistor laser

    Science.gov (United States)

    Liang, Song; Qiao, Lijun; Zhu, Hongliang; Wang, Wei

    2016-06-01

    A transistor laser (TL), having the structure of a transistor with multi-quantum wells near its base region, bridges the functionality gap between lasers and transistors. However, light emission is produced at the expense of current gain for all the TLs reported up to now, leading to a very low current gain. We propose a novel design of TLs, which have an n-doped InP layer inserted in the emitter ridge. Numerical studies show that a current flow aperture for only holes can be formed in the center of the emitter ridge. As a result, the common emitter current gain can be as large as 143.3, which is over 15 times larger than that of a TL without the aperture. Besides, the effects of nonradiative recombination defects can be reduced greatly because the flow of holes is confined in the center region of the emitter ridge.

  20. Innovative Design for Adaptive Detection Module of In-pipe Robot Based on TRIZ%基于TRIZ的管道机器人自适应检测模块创新设计

    Institute of Scientific and Technical Information of China (English)

    夏文涵; 王凯; 李彦; 熊艳

    2016-01-01

    For the problem of detection module of in-pipe robot system "PipeGuard" could not detect the pipe with different diameter during process of inspection, a method of innovative design for adaptive detection module based on TRIZ is proposed. A innovative design process model of pipe detection module which is based on TRIZ substance-field model and conflict resolution theory, is established. The proposed method achieves adaptive inspection of the pipes with different diameters. By defining TRIZ problem, the TRIZ substance-field model’s standard solution, and the separable principle and inventive principle of conflict resolution theory are used to solve the design problem. A separable drums and a membrane are adopt to detect he pipes with different diameters. When the pipe’s diameter increases, the elastic drum and membrane will be elongated by spring’s elasticity to fit the changed diameter of the pipe and then inspect the pipe. When the pipe’s diameter decreases, the elastic drum and membrane will be adaptively shrink by the pressure of the pipe wall. Finally, solution strategy is verified by the mechanical analysis mechanical analysis and mathematical model. And then, supply the factors and detect methods for detection accuracy and sensitivity.%针对管道检测机器人系统“PipeGuard”的检测模块在检测过程中无法自适应检测不同直径的管道这一问题,提出一种基于发明问题求解理论(Theory of inventive problem solving,TRIZ)的自适应检测模块的创新设计方法,建立基于TRIZ物场模型和冲突解决理论的管道检测模块创新设计过程模型,实现了对不同直径管道的自适应检测。通过定义TRIZ问题,综合采用TRIZ物场分析模型的标准解以及冲突解决理论的分离原理和发明原理求解该设计问题。采用一种可分离的弹性鼓、膜实现了自适应检测不同直径的管道。当管道直径变大时,弹性鼓、膜通过弹簧的作用力而伸

  1. Development of the module inspection system for new standardized radiation monitoring modules

    International Nuclear Information System (INIS)

    This report mentions about the module inspection system which does the maintenance check of the monitoring modules adapted the new monitoring standard, as well as the result of the verification of the modules. The module inspection system is the automatic measurement system with the computer. The system can perform the functional and the characteristic examination of the monitoring modules, the calibration with radiation source and inspection report. In the verification of the monitoring module, three major items were tested, the adaptability for the new monitoring standard, the module functions and each characteristics. All items met the new monitoring standard. (author)

  2. Adaptive Lighting

    OpenAIRE

    Petersen, Kjell Yngve; Søndergaard, Karin; Kongshaug, Jesper

    2015-01-01

    Adaptive LightingAdaptive lighting is based on a partial automation of the possibilities to adjust the colour tone and brightness levels of light in order to adapt to people’s needs and desires. IT support is key to the technical developments that afford adaptive control systems. The possibilities offered by adaptive lighting control are created by the ways that the system components, the network and data flow can be coordinated through software so that the dynamic variations are controlled i...

  3. Heritability of gestational weight gain

    DEFF Research Database (Denmark)

    Andersson, Elina Scheers; Silventoinen, Karri; Tynelius, Per;

    2015-01-01

    Gestational weight gain (GWG) is a complex trait involving intrauterine environmental, maternal environmental, and genetic factors. However, the extent to which these factors contribute to the total variation in GWG is unclear. We therefore examined the genetic and environmental influences on the...

  4. Gain recovery dynamics and limitations in quantum dot amplifiers

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Bischoff, Svend; Magnúsdóttir, Ingibjörg;

    2001-01-01

    Summary form only given. While ultra-low threshold current densities have been achieved in quantum dot (QD) lasers, the predicted potential for high-speed modulation has not yet been realized despite the high differential gain. Furthermore, recent single pulse experiments demonstrated very fast...... gain recovery in a quantum dot amplifier, and it is thus not yet clear what the limiting processes for the device response are. We present the results of a comprehensive theoretical model, which agrees well with the experimental results, and indicates the importance of slow recovery of higher energy...

  5. Traffic-Adaptive Routing

    OpenAIRE

    Kammenhuber, Nils

    2011-01-01

    Despite the bursty and highly volatile traffic, routing in the Internet today is optimised only on coarse time scales, as load-adaptive routing is known to induce performance deterioration by causing massive oscillations. We describe ReplEx, an universally applicable distributed algorithm for dynamic routing/traffic engineering, which is based on game theory. We show through extensive realistic simulations that ReplEx does not oscillate, and that it achieves performance gains comparable to tr...

  6. Self-adaptive robot training of stroke survivors for continuous tracking movements

    Directory of Open Access Journals (Sweden)

    Morasso Pietro

    2010-03-01

    Full Text Available Abstract Background Although robot therapy is progressively becoming an accepted method of treatment for stroke survivors, few studies have investigated how to adapt the robot/subject interaction forces in an automatic way. The paper is a feasibility study of a novel self-adaptive robot controller to be applied with continuous tracking movements. Methods The haptic robot Braccio di Ferro is used, in relation with a tracking task. The proposed control architecture is based on three main modules: 1 a force field generator that combines a non linear attractive field and a viscous field; 2 a performance evaluation module; 3 an adaptive controller. The first module operates in a continuous time fashion; the other two modules operate in an intermittent way and are triggered at the end of the current block of trials. The controller progressively decreases the gain of the force field, within a session, but operates in a non monotonic way between sessions: it remembers the minimum gain achieved in a session and propagates it to the next one, which starts with a block whose gain is greater than the previous one. The initial assistance gains are chosen according to a minimal assistance strategy. The scheme can also be applied with closed eyes in order to enhance the role of proprioception in learning and control. Results The preliminary results with a small group of patients (10 chronic hemiplegic subjects show that the scheme is robust and promotes a statistically significant improvement in performance indicators as well as a recalibration of the visual and proprioceptive channels. The results confirm that the minimally assistive, self-adaptive strategy is well tolerated by severely impaired subjects and is beneficial also for less severe patients. Conclusions The experiments provide detailed information about the stability and robustness of the adaptive controller of robot assistance that could be quite relevant for the design of future large scale

  7. An Optimal Control Modification to Model-Reference Adaptive Control for Fast Adaptation

    Science.gov (United States)

    Nguyen, Nhan T.; Krishnakumar, Kalmanje; Boskovic, Jovan

    2008-01-01

    This paper presents a method that can achieve fast adaptation for a class of model-reference adaptive control. It is well-known that standard model-reference adaptive control exhibits high-gain control behaviors when a large adaptive gain is used to achieve fast adaptation in order to reduce tracking error rapidly. High gain control creates high-frequency oscillations that can excite unmodeled dynamics and can lead to instability. The fast adaptation approach is based on the minimization of the squares of the tracking error, which is formulated as an optimal control problem. The necessary condition of optimality is used to derive an adaptive law using the gradient method. This adaptive law is shown to result in uniform boundedness of the tracking error by means of the Lyapunov s direct method. Furthermore, this adaptive law allows a large adaptive gain to be used without causing undesired high-gain control effects. The method is shown to be more robust than standard model-reference adaptive control. Simulations demonstrate the effectiveness of the proposed method.

  8. Gain functionalization of silica microresonators.

    Science.gov (United States)

    Yang, Lan; Vahala, K J

    2003-04-15

    Erbium-doped solgel films are applied to the surface of silica microspheres to create low-threshold microactivity lasers. This gain functionalization can be applied by use of a number of different dopants, thereby extending the wavelength range of this class of device. Also, by varying the doping concentration and thickness of the applied solgel layer, one can vary the laser dynamics so that both continuous-wave and pulsating modes of operation are possible. PMID:12703910

  9. The human milk oligosaccharide 2'-fucosyllactose augments the adaptive response to extensive intestinal.

    Science.gov (United States)

    Mezoff, Ethan A; Hawkins, Jennifer A; Ollberding, Nicholas J; Karns, Rebekah; Morrow, Ardythe L; Helmrath, Michael A

    2016-03-15

    Intestinal resection resulting in short bowel syndrome (SBS) carries a heavy burden of long-term morbidity, mortality, and cost of care, which can be attenuated with strategies that improve intestinal adaptation. SBS infants fed human milk, compared with formula, have more rapid intestinal adaptation. We tested the hypothesis that the major noncaloric human milk oligosaccharide 2'-fucosyllactose (2'-FL) contributes to the adaptive response after intestinal resection. Using a previously described murine model of intestinal adaptation, we demonstrated increased weight gain from 21 to 56 days (P < 0.001) and crypt depth at 56 days (P < 0.0095) with 2'-FL supplementation after ileocecal resection. Furthermore, 2'-FL increased small bowel luminal content microbial alpha diversity following resection (P < 0.005) and stimulated a bloom in organisms of the genus Parabacteroides (log2-fold = 4.1, P = 0.035). Finally, transcriptional analysis of the intestine revealed enriched ontologies and pathways related to antimicrobial peptides, metabolism, and energy processing. We conclude that 2'-FL supplementation following ileocecal resection increases weight gain, energy availability through microbial community modulation, and histological changes consistent with improved adaptation.

  10. Potential impact of contrails on solar energy gain

    Directory of Open Access Journals (Sweden)

    P. Weihs

    2014-08-01

    Full Text Available We investigated the effect of contrails on global shortwave radiation and on solar energy gain. The study was done for days with a high contrail persistence and looking at situations where the contrails were obstructing the sun. Measurements of cloudiness using a fish eye camera, diffuse and direct shortwave measurements and measurements of the short circuit current of three different types of photovoltaic (PV modules were performed at the solar observatory Kanzelhöhe (1540 m a.s.l. during a period of one year with a time resolution of one minute. Our results show that contrails moving between sun and observer/sensor may reduce the global radiation by up to 72%. A statistic of contrail persistence and influence of contrails on global irradiance and solar energy gain is presented. The losses in solar energy gain that were recorded may even be critical under some circumstances for PV system performance.

  11. Gaining Confidence in Scientific Applications Through Executable Interface Contracts

    Energy Technology Data Exchange (ETDEWEB)

    Dahlgren, T; Bernholdt, D; McInnes, L C

    2008-06-16

    Interface contract enforcement is intended to help scientists gain confidence in software built from third-party components. Unfamiliar components present increased risk of incorrect or unanticipated usage patterns and unexpected component behavior. Executable interface contracts can address these issues but may incur unacceptable overhead. Research into techniques for performance-driven contract enforcement pursues practical solutions to adapting the level of contract enforcement to performance constraints.

  12. Gaining and sustaining schistosomiasis control

    DEFF Research Database (Denmark)

    Ezeamama, Amara E; He, Chun-La; Shen, Ye;

    2016-01-01

    strategies. RESULTS: These studies of different treatment schedules with PZQ will provide the most comprehensive data thus far on the optimal frequency and continuity of PCT for schistosomiasis infection and morbidity control. CONCLUSIONS: We expect that the study outcomes will provide data for decision...... 2009, SCORE held a series of meetings to specify empirical questions and design studies related to different schedules of PCT for schistosomiasis control in communities with high (gaining control studies) and moderate (sustaining control studies) prevalence of Schistosoma infection among school...

  13. Adaptive Lighting

    DEFF Research Database (Denmark)

    Petersen, Kjell Yngve; Søndergaard, Karin; Kongshaug, Jesper

    2015-01-01

    Adaptive Lighting Adaptive lighting is based on a partial automation of the possibilities to adjust the colour tone and brightness levels of light in order to adapt to people’s needs and desires. IT support is key to the technical developments that afford adaptive control systems. The possibilities...... offered by adaptive lighting control are created by the ways that the system components, the network and data flow can be coordinated through software so that the dynamic variations are controlled in ways that meaningfully adapt according to people’s situations and design intentions. This book discusses...... distributed differently into an architectural body. We also examine what might occur when light is dynamic and able to change colour, intensity and direction, and when it is adaptive and can be brought into interaction with its surroundings. In short, what happens to an architectural space when artificial...

  14. Abelian modules

    OpenAIRE

    S. Halıcıoğlu; Harmanci, A.; GÜNGÖROĞLU, G.; N. Agayev

    2009-01-01

    In this note, we introduce abelian modules as a generalization of abelian rings. Let R be an arbitrary ring with identity. A module M is called abelian if, for any m Î M and any a Î R, any idempotent e Î R, mae=mea. We prove that every reduced module, every symmetric module, every semicommutative module and every Armendariz module is abelian. For an abelian ring R, we show that the module MR is abelian iff M[x]R[x] is abelian. We produce an example to show that M[x, α] need not be abe...

  15. Estimating the potential gains from mergers

    DEFF Research Database (Denmark)

    Bogetoft, Peter; Wang, Dexiang

    2005-01-01

    We introduce simple production economic models to estimate the potential gains from mergers. We decompose the gains into technical ef¿ciency, size (scale) and harmony (mix) gains, and we discuss alternative ways to capture these gains. We propose to approximate the production processes using...... the non-parametric. Data Envelopment Analysis (DEA) approach, and we use the resulting operational approach to estimate the potential gains from merging agricultural extension of¿ces in Denmark....

  16. Dual adaptation and adaptive generalization of the human vestibulo-ocular reflex

    Science.gov (United States)

    Welch, R. B.; Bridgeman, B.; Williams, J. A.; Semmler, R.

    1998-01-01

    In two experiments, we examined the possibility that the human vestibulo-ocular reflex (VOR) is subject to dual adaptation (the ability to adapt to a sensory rearrangement more rapidly and/or more completely after repeated experience with it) and adaptive generalization (the ability to adapt more readily to a novel sensory rearrangement as a result of prior dual adaptation training). In Experiment 1, the subjects actively turned the head during alternating exposure to a visual-vestibular rearrangement (target/head gain = 0.5) and the normal situation (target/head gain = 0.0). These conditions produced both adaptation and dual adaptation of the VOR but no evidence of adaptive generalization when tested with a target/head gain of 1.0. Experiment 2, in which exposure to the 0.5 gain entailed externally controlled (i.e., passive) whole body rotation, resulted in VOR adaptation but no dual adaptation. As in Experiment 1, no evidence of adaptive generalization was found.

  17. TPC1 - SV Channels Gain Shape

    Institute of Scientific and Technical Information of China (English)

    Rainer Hedrich; Irene Marten

    2011-01-01

    T The most prominent ion channel localized in plant vacuoles is the slow activating SV type. Slow vacuolar (SV)channels were discovered by patch clamp studies as early as 1986. In the following two decades, numerous studies revealed that these calcium- and voltage-activated, nonselective cation channels are expressed in the vacuoles of all plants and every plant tissue. The voltage-dependent properties of the SV channel are susceptible to modulation by calcium, pH, redox state, as well as regulatory proteins. In Arabidopsis, the SV channel is encoded by the AtTPC1 gene, and even though its gene product represents the by far largest conductance of the vacuolar membrane, tpc1-loss-of-function mutants appeared not to be impaired in major physiological functions such as growth, development, and reproduction. In contrast, the fou2 gain-of-function point mutation D454N within TPC1 leads to a pronounced growth phenotype and increased synthesis of the stress hormone jasmonate. Since the TPC1 gene is present in all land plants, it likely encodes a very general function. In this review, we will discuss major SV channel properties and their impact on plant cell physiology.

  18. Solar tomography adaptive optics.

    Science.gov (United States)

    Ren, Deqing; Zhu, Yongtian; Zhang, Xi; Dou, Jiangpei; Zhao, Gang

    2014-03-10

    Conventional solar adaptive optics uses one deformable mirror (DM) and one guide star for wave-front sensing, which seriously limits high-resolution imaging over a large field of view (FOV). Recent progress toward multiconjugate adaptive optics indicates that atmosphere turbulence induced wave-front distortion at different altitudes can be reconstructed by using multiple guide stars. To maximize the performance over a large FOV, we propose a solar tomography adaptive optics (TAO) system that uses tomographic wave-front information and uses one DM. We show that by fully taking advantage of the knowledge of three-dimensional wave-front distribution, a classical solar adaptive optics with one DM can provide an extra performance gain for high-resolution imaging over a large FOV in the near infrared. The TAO will allow existing one-deformable-mirror solar adaptive optics to deliver better performance over a large FOV for high-resolution magnetic field investigation, where solar activities occur in a two-dimensional field up to 60'', and where the near infrared is superior to the visible in terms of magnetic field sensitivity.

  19. Adaptive Lighting

    DEFF Research Database (Denmark)

    Petersen, Kjell Yngve; Søndergaard, Karin; Kongshaug, Jesper

    2015-01-01

    Adaptive Lighting Adaptive lighting is based on a partial automation of the possibilities to adjust the colour tone and brightness levels of light in order to adapt to people’s needs and desires. IT support is key to the technical developments that afford adaptive control systems. The possibilities...... offered by adaptive lighting control are created by the ways that the system components, the network and data flow can be coordinated through software so that the dynamic variations are controlled in ways that meaningfully adapt according to people’s situations and design intentions. This book discusses...... the investigations of lighting scenarios carried out in two test installations: White Cube and White Box. The test installations are discussed as large-scale experiential instruments. In these test installations we examine what could potentially occur when light using LED technology is integrated and...

  20. Information gains from cosmological probes

    Science.gov (United States)

    Grandis, S.; Seehars, S.; Refregier, A.; Amara, A.; Nicola, A.

    2016-05-01

    In light of the growing number of cosmological observations, it is important to develop versatile tools to quantify the constraining power and consistency of cosmological probes. Originally motivated from information theory, we use the relative entropy to compute the information gained by Bayesian updates in units of bits. This measure quantifies both the improvement in precision and the `surprise', i.e. the tension arising from shifts in central values. Our starting point is a WMAP9 prior which we update with observations of the distance ladder, supernovae (SNe), baryon acoustic oscillations (BAO), and weak lensing as well as the 2015 Planck release. We consider the parameters of the flat ΛCDM concordance model and some of its extensions which include curvature and Dark Energy equation of state parameter w. We find that, relative to WMAP9 and within these model spaces, the probes that have provided the greatest gains are Planck (10 bits), followed by BAO surveys (5.1 bits) and SNe experiments (3.1 bits). The other cosmological probes, including weak lensing (1.7 bits) and {H0} measures (1.7 bits), have contributed information but at a lower level. Furthermore, we do not find any significant surprise when updating the constraints of WMAP9 with any of the other experiments, meaning that they are consistent with WMAP9. However, when we choose Planck15 as the prior, we find that, accounting for the full multi-dimensionality of the parameter space, the weak lensing measurements of CFHTLenS produce a large surprise of 4.4 bits which is statistically significant at the 8 σ level. We discuss how the relative entropy provides a versatile and robust framework to compare cosmological probes in the context of current and future surveys.

  1. The Adaptive Evolution Database (TAED)

    OpenAIRE

    Liberles, David A; Schreiber, David R.; Govindarajan, Sridhar; Chamberlin, Stephen G.; Steven A Benner

    2001-01-01

    Background The Master Catalog is a collection of evolutionary families, including multiple sequence alignments, phylogenetic trees and reconstructed ancestral sequences, for all protein-sequence modules encoded by genes in GenBank. It can therefore support large-scale genomic surveys, of which we present here The Adaptive Evolution Database (TAED). In TAED, potential examples of positive adaptation are identified by high values for the normalized ratio of nonsynonymous to synonymous nucleotid...

  2. Sudden gains in behavioural activation for depression.

    Science.gov (United States)

    Masterson, Ciara; Ekers, David; Gilbody, Simon; Richards, David; Toner-Clewes, Benjamin; McMillan, Dean

    2014-09-01

    Sudden gains have been linked to improved outcomes in cognitive behaviour therapy for depression. The relationship between sudden gains and outcome is less clear in other treatment modalities, including interpersonal psychotherapy and supportive expressive therapy, which may indicate different mechanisms of change between treatment modalities. The current study examined sudden gains in adults meeting diagnostic criteria for depression (N = 40) offered up to 12 sessions of behavioural activation treatment. Sudden gains were found in 42.5% of the sample. Sudden gains occurred early (median pre-gain session 2) and were related to outcome: those who experienced a sudden gain had significantly lower post-treatment scores on the PHQ-9. Furthermore, the proportion meeting the reliable and clinically significant change criteria at end of treatment was higher in the sudden gain group. These findings highlight the importance of understanding the mechanisms by which sudden gains relate to therapy outcome in behavioural activation.

  3. Adaptive Computing.

    Science.gov (United States)

    Harrell, William

    1999-01-01

    Provides information on various adaptive technology resources available to people with disabilities. (Contains 19 references, an annotated list of 129 websites, and 12 additional print resources.) (JOW)

  4. ADAPT Dataset

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced Diagnostics and Prognostics Testbed (ADAPT) Project Lead: Scott Poll Subject Fault diagnosis in electrical power systems Description The Advanced...

  5. The Flynn effect in Korea: large gains

    OpenAIRE

    te Nijenhuis, Jan; Cho, Sun Hee; Murphy, Raegan; Lee, Kun Ho

    2012-01-01

    Secular gains in IQ test scores have been reported for many Western countries. This is the first study of secular IQ gains in South Korea, using various datasets. The first question is what the size of the Flynn effect in South Korea is. The gains per decade are 7.7 points for persons born between 1970 and 1990. These gains on broad intelligence batteries are much larger than the gains in Western countries of about 3 IQ points per decade. The second question is whether the Korean IQ gains are...

  6. Spike-frequency adaptation generates intensity invariance in a primary auditory interneuron.

    Science.gov (United States)

    Benda, Jan; Hennig, R Matthias

    2008-04-01

    Adaptation of the spike-frequency response to constant stimulation, as observed on various timescales in many neurons, reflects high-pass filter properties of a neuron's transfer function. Adaptation in general, however, is not sufficient to make a neuron's response independent of the mean intensity of a sensory stimulus, since low frequency components of the stimulus are still transmitted, although with reduced gain. We here show, based on an analytically tractable model, that the response of a neuron is intensity invariant, if the fully adapted steady-state spike-frequency response to constant stimuli is independent of stimulus intensity. Electrophysiological recordings from the AN1, a primary auditory interneuron of crickets, show that for intensities above 60 dB SPL (sound pressure level) the AN1 adapted with a time-constant of approximately 40 ms to a steady-state firing rate of approximately 100 Hz. Using identical random amplitude-modulation stimuli we verified that the AN1's spike-frequency response is indeed invariant to the stimulus' mean intensity above 60 dB SPL. The transfer function of the AN1 is a band pass, resulting from a high-pass filter (cutoff frequency at 4 Hz) due to adaptation and a low-pass filter (100 Hz) determined by the steady-state spike frequency. Thus, fast spike-frequency adaptation can generate intensity invariance already at the first level of neural processing.

  7. Flood adaptive traits and processes : An overview

    NARCIS (Netherlands)

    Voesenek, Laurentius A C J; Bailey-Serres, Julia

    2015-01-01

    Unanticipated flooding challenges plant growth and fitness in natural and agricultural ecosystems. Here we describe mechanisms of developmental plasticity and metabolic modulation that underpin adaptive traits and acclimation responses to waterlogging of root systems and submergence of aerial tissue

  8. Adaptive holography for optical sensing applications

    Science.gov (United States)

    Residori, S.; Bortolozzo, U.; Peigné, A.; Molin, S.; Nouchi, P.; Dolfi, D.; Huignard, J. P.

    2016-03-01

    Adaptive holography is a promising method for high sensitivity phase modulation measurements in the presence of slow perturbations from the environment. The technique is based on the use of a nonlinear recombining medium, here an optically addressed spatial light modulator specifically realized to operate at 1.55 μm. Owing to the physical mechanisms involved, the interferometer adapts to slow phase variations within a range of 5-10 Hz, thus filtering out low frequency noise while transmitting higher frequency phase modulations. We present the basic principles of the adaptive interferometer and show that it can be used in association with a sensing fiber in order to detect phase modulations. Finally, a phase-OTDR architecture using the adaptive holographic interferometer is presented and shown to allows the detection of localized perturbations along the sensing fiber.

  9. Review of High Gain FELs

    International Nuclear Information System (INIS)

    For understanding on basic radiation mechanism of the high-gain FEL based on SASE, the author presents electron-crystal interpretation of FEL radiation. In the electron-crystal, electrons are localized at regularly spaced multi-layers, which represents micro-bunching, whose spacing is equal to the radiation wavelength, and the multi-layers are perpendicular to beam axis, thus, diffracted wave creates Bragg's spots in forward and backward directions. Due to the Doppler's effect, frequency of the back-scattered wave is up-converted, generates forwardly focused X-ray. The Bragg's effect contributes focusing the X-ray beam into a spot, thus peak power becomes extremely higher by factor of typically 107. This is the FEL radiation. As well known, the total numbers of scattered photons in Bragg's spots is equal to the total elastic scattering photons from the atoms contained in the crystal. Therefore, total power in the FEL laser is same as the spontaneous radiation power from the undulator for the same beam parameter. The FEL radiation phenomenon is simple interference effect. In today's presentations, we use the laser pointer, and we frequently experience difficulty in pointing precisely or steadily in one place on the screen, since the laser spot is very small and does not spread. Exactly same to this, X-ray FEL is a highly focused beam, and pointing stability dominates productivity of experiment, thus we need special care on beam stability from linear accelerator

  10. Adaptive algorithms of position and energy reconstruction in Anger-camera type detectors: experimental data processing in ANTS

    Science.gov (United States)

    Morozov, A.; Defendi, I.; Engels, R.; Fraga, F. A. F.; Fraga, M. M. F. R.; Gongadze, A.; Guerard, B.; Jurkovic, M.; Kemmerling, G.; Manzin, G.; Margato, L. M. S.; Niko, H.; Pereira, L.; Petrillo, C.; Peyaud, A.; Piscitelli, F.; Raspino, D.; Rhodes, N. J.; Sacchetti, F.; Schooneveld, E. M.; Solovov, V.; Van Esch, P.; Zeitelhack, K.

    2013-05-01

    The software package ANTS (Anger-camera type Neutron detector: Toolkit for Simulations), developed for simulation of Anger-type gaseous detectors for thermal neutron imaging was extended to include a module for experimental data processing. Data recorded with a sensor array containing up to 100 photomultiplier tubes (PMT) or silicon photomultipliers (SiPM) in a custom configuration can be loaded and the positions and energies of the events can be reconstructed using the Center-of-Gravity, Maximum Likelihood or Least Squares algorithm. A particular strength of the new module is the ability to reconstruct the light response functions and relative gains of the photomultipliers from flood field illumination data using adaptive algorithms. The performance of the module is demonstrated with simulated data generated in ANTS and experimental data recorded with a 19 PMT neutron detector. The package executables are publicly available at http://coimbra.lip.pt/~andrei/

  11. AN OVERVIEW OF THE DEVELOPMENT OF LOW GAIN FEEDBACK AND LOW-AND-HIGH GAIN FEEDBACK

    Institute of Scientific and Technical Information of China (English)

    Zongli LIN

    2009-01-01

    Low gain feedback refers to certain families of stabilizing state feedback gains that are parameterized in a scalar and go to zero as the scalar decreases to zero. Low gain feedback was initially proposed to achieve semi-global stabilization of linear systems subject to input saturation. It was then combined with high gain feedback in different ways for solving various control problems. The resulting feedback laws are referred to as low-and-high gain feedback. Since the introduction of low gain feedback in the context of semi-global stabilization of linear systems subject to input saturation,there has been effort to develop alternative methods for low gain design, to characterize key features of low gain feedback, and to explore new applications of the low gain and low-and-high gain feedback.This paper reviews the developments in low gain and low-and-high gain feedback designs.

  12. The Flynn effect in Korea: Large gains

    NARCIS (Netherlands)

    J. te Nijenhuis; S.H. Cho; R. Murphy; K.H. Lee

    2012-01-01

    Secular gains in IQ test scores have been reported for many Western countries. This is the first study of secular IQ gains in South Korea, using various datasets. The first question is what the size of the Flynn effect in South Korea is. The gains per decade are 7.7 points for persons born between 1

  13. Determination of optimal gains for constrained controllers

    Energy Technology Data Exchange (ETDEWEB)

    Kwan, C.M.; Mestha, L.K.

    1993-08-01

    In this report, we consider the determination of optimal gains, with respect to a certain performance index, for state feedback controllers where some elements in the gain matrix are constrained to be zero. Two iterative schemes for systematically finding the constrained gain matrix are presented. An example is included to demonstrate the procedures.

  14. Adaptive Large Neighbourhood Search

    DEFF Research Database (Denmark)

    Røpke, Stefan

    Large neighborhood search is a metaheuristic that has gained popularity in recent years. The heuristic repeatedly moves from solution to solution by first partially destroying the solution and then repairing it. The best solution observed during this search is presented as the final solution....... This tutorial introduces the large neighborhood search metaheuristic and the variant adaptive large neighborhood search that dynamically tunes parameters of the heuristic while it is running. Both heuristics belong to a broader class of heuristics that are searching a solution space using very large...... neighborhoods. The tutorial also present applications of the adaptive large neighborhood search, mostly related to vehicle routing problems for which the heuristic has been extremely successful. We discuss how the heuristic can be parallelized and thereby take advantage of modern desktop computers...

  15. Neural network with dynamically adaptable neurons

    Science.gov (United States)

    Tawel, Raoul (Inventor)

    1994-01-01

    This invention is an adaptive neuron for use in neural network processors. The adaptive neuron participates in the supervised learning phase of operation on a co-equal basis with the synapse matrix elements by adaptively changing its gain in a similar manner to the change of weights in the synapse IO elements. In this manner, training time is decreased by as much as three orders of magnitude.

  16. Characteristics of eye-position gain field populations determine geometry of visual space

    Directory of Open Access Journals (Sweden)

    Sidney R Lehky

    2016-01-01

    Full Text Available We have previously demonstrated differences in eye-position spatial maps for anterior inferotemporal cortex (AIT in the ventral stream and lateral intraparietal cortex (LIP in the dorsal stream, based on population decoding of gaze angle modulations of neural visual responses (i.e., eye-position gain fields. Here we explore the basis of such spatial encoding differences through modeling of gain field characteristics. We created a population of model neurons, each having a different eye-position gain field. This population was used to reconstruct eye-position visual space using multidimensional scaling. As gain field shapes have never been well established experimentally, we examined different functions, including planar, sigmoidal, elliptical, hyperbolic, and mixtures of those functions. All functions successfully recovered positions, indicating weak constraints on allowable gain field shapes. We then used a genetic algorithm to modify the characteristics of model gain field populations until the recovered spatial maps closely matched those derived from monkey neurophysiological data in AIT and LIP. The primary differences found between model AIT and LIP gain fields were that AIT gain fields were more foveally dominated. That is, gain fields in AIT operated on smaller spatial scales and smaller dispersions than in LIP. Thus we show that the geometry of eye-position visual space depends on the population characteristics of gain fields, and that differences in gain field characteristics for different cortical areas may underlie differences in the representation of space.

  17. High Resolution Open-Loop Adaptive Optics System for Retinal Imaging Based on Liquid Crystal Spatial Light Modulator%高分辨率开环液晶自适应光学视网膜成像系统

    Institute of Scientific and Technical Information of China (English)

    齐岳; 孔宁宁; 李大禹; 夏明亮; 宣丽

    2012-01-01

    利用液晶空间光调制器和夏克-哈特曼波前探测器作为核心器件搭建了一套开环双光源液晶自适应光学视网膜成像系统.系统采用人眼屈光0D基准设计并使用动态视标定位人眼,提高了人眼在测试时的稳定性,有效降低了由不同人眼个体差异带来的影响.通过补偿镜预补偿,配合微调照明光焦面,使照明光聚焦在眼底视觉细胞层,保证了像差探测精度和成像质量.利用人眼的偏振特性,采用偏振光照明的方式,将系统的能量利用率提高了20%.优化了系统的工作流程,优化后系统连续工作频率可超过20 Hz.对4名志愿者进行了实验,均获得了清晰的眼底视网膜细胞图像.%An open-loop adaptive optics system with liquid crystal spatial light modulator and Shark-Hartmann wavefront sensor is constructed. The system is designed according to zero diopter. Compared with the static target,the stability of the pupil increases obviously while staring at the dynamic target during the experiment. The impact of individual differences on human eyes has been reduced effectively. The focal plane of the light source can be axial shifted to ensure it can reach the photoreceptors layer of the retina with the help of trial lens. The fundus is illuminated by polarized light and the energy efficiency increases by 20% . The control flow of the system is optimized and the continuous working frequency of the system is above 20 Hz. Four volunteers are participated in the experiments. Both of them obtain the clear photoreceptor images after corrections.

  18. Small signal gain in DPAL systems

    Science.gov (United States)

    Galbally-Kinney, Kristin L.; Maser, Daniel L.; Kessler, William J.; Rawlins, Wilson T.; Davis, Steven J.

    2011-03-01

    In this paper we describe a platform for small signal gain measurements for alkali atom laser systems based on the DPAL excitation method. We present initial results that clearly show the transition from absorption on the alkali atom D1 lines in Cs and Rb to optical transparency and positive gain. The achievement of optical gain is critically dependent upon alkali cell conditions and collision partners. We also present the first spatially resolved gain measurements in a DPAL system. The small signal gain methods described will be valuable tools for power scaling of these laser systems.

  19. Do low-calorie sweeteners promote weight gain in rodents?

    Science.gov (United States)

    Glendinning, John I

    2016-10-01

    Low-calorie sweeteners (LCSs) are used globally to increase the palatability of foods and beverages, without the calories of sugar. Recently, however, there have been claims that LCSs promote obesity. Here, I review the literature linking LCS consumption to elevated body weight in rodents. A recent systematic review found when the LCSs were presented in water or chow, only a minority of the studies reported elevated weight gain. In contrast, when the LCSs were presented in yogurt, the majority of the studies reported elevated weight gain. This review focuses on this latter subset of studies, and asks why the combination of LCSs and yogurt promoted weight gain. First, LCSs have been hypothesized to induce metabolic derangement because they uncouple sweet taste and calories. However, the available evidence indicates that the LCS-treated yogurts did not actually taste sweet to rats in the published studies. Without a sweet taste, the concerns about uncoupling sweet taste and calories would not be relevant. Second, in several studies, the LCS-treated yogurt increased weight gain without increasing caloric intake. This indicates that caloric intake alone cannot explain the elevated weight gain. Third, there is evidence that LCSs and yogurt can each alter the gut microbiota of rodents. Given recent work indicating that changes in gut microbiota can modulate body weight, it is possible that the combination of LCS and yogurt alters the gut microbiota in ways that promote weight gain. While this hypothesis remains speculative, it is consistent with the observed rodent data. In human studies, LCSs are usually presented in beverages. Based on the rodent work, it might be worthwhile to evaluate the impact of LCS-treated yogurt in humans.

  20. Throughput Gain Using Threshold-Based Multiuser Scheduling in WiMAX OFDMA

    Directory of Open Access Journals (Sweden)

    Sulyman AhmedIyanda

    2011-01-01

    Full Text Available This paper presents the analysis of the throughput enhancement possible using threshold-based multiuser scheduling in WiMAX OFDMA. We consider a point-to-multipoint (PMP WiMAX network where base station (BS schedules downlink packets for simultaneous transmissions to multiple users using the WiMAX OFDMA system. WiMAX OFDMA standard specifies several subcarrier permutation options, such as the partial usage of subcarriers (PUSC, full usage of subcarrier (FUSC, and the band adaptive modulation and coding (band-AMC among others, for mapping the physical subcarriers into logical subchannels assigned to users by the BS schedulers. In this paper, we propose the use of threshold testing prior to the process of subchannel assignment to users by the BS scheduler, as a means of throughput enhancement. In the proposed threshold-based multiuser scheduling scheme, the BS scheduler selects at any time instant users whose channel gains in the available subchannels equal or exceed a predetermined energy threshold. Thus, only users who can maximize BS throughput on the available subchannels are assigned data transmission opportunities which enhance the BS data rate, albeit at the expense of fairness to users. We quantify the throughput enhancement of the proposed system and illustrate its benefits by numerical simulations.

  1. Extended High-Gain Observer for Mars Entry Guidance

    Directory of Open Access Journals (Sweden)

    Pingyuan Cui

    2013-02-01

    Full Text Available To deliver a Mars entry vehicle to the prescribed parachute deployment point, active entry guidance is essential. This paper addresses the problem of Mars atmospheric entry guidance through drag tracking method with extended high gain observer. First, an extended high gain observer combined with feedback linearization is applied in drag tracking for Mars entry longitudinal guidance.  The observer estimates the drag and drag rate for drag tracking, estimates the perturbation due to model uncertainty and disturbance, and compensate for the perturbation by canceling its estimate. Then, bank reversal is adopted in the lateral plane to reduce the cross-range error. Finally, Mars entry simulation is performed to assess the performance of the adaptive guidance law. The results demonstrate that the proposed guidance law exhibits good performance.

  2. Application of gain scheduling to the control of batch bioreactors

    Science.gov (United States)

    Cardello, Ralph; San, Ka-Yiu

    1987-01-01

    The implementation of control algorithms to batch bioreactors is often complicated by the inherent variations in process dynamics during the course of fermentation. Such a wide operating range may render the performance of fixed gain PID controllers unsatisfactory. In this work, a detailed study on the control of batch fermentation is performed. Furthermore, a simple batch controller design is proposed which incorporates the concept of gain-scheduling, a subclass of adaptive control, with oxygen uptake rate as an auxiliary variable. The control of oxygen tension in the biorector is used as a vehicle to convey the proposed idea, analysis and results. Simulation experiments indicate significant improvement in controller performance can be achieved by the proposed approach even in the presence of measurement noise.

  3. Multi-Directional Motion Adaptation

    Directory of Open Access Journals (Sweden)

    David Patrick McGovern

    2012-05-01

    Full Text Available The direction aftereffect (DAE is a phenomenon whereby prolonged exposure to a moving stimulus biases the perceived direction of subsequent stimuli. It is believed to arise through a selective suppression of directionally tuned neurons in the visual cortex, causing shifts in the population response away from the adapted direction. Whereas most studies consider only unidirectional adaptation, here we examine how concurrent adaptation to multiple directions affects the DAE. Observers were required to judge whether a random dot kinematogram (RDK moved clockwise or counter-clockwise relative to upwards. In different conditions, observers adapted to a stimulus comprised of directions drawn from a distribution or to bidirectional motion. Increasing the variance of normally distributed directions reduced the magnitude of the peak DAE and broadened its tuning profile. Asymmetric sampling of Gaussian and uniform distributions resulted in shifts of DAE tuning profiles consistent with changes in the perceived global direction of the adapting stimulus. Discrimination thresholds were elevated by an amount that related to the magnitude of the bias. For bidirectional adaptors, adding dots in directions away from the adapting motion led to a pronounced reduction in the DAE. This reduction was observed when dots were added in opposite or orthogonal directions to the adaptor suggesting that it may arise via inhibition from a broadly tuned normalisation pool. Preliminary simulations with a population coding model, where the gain of a direction-selective neuron is inversely proportional to its response to the adapting stimulus, suggest that it provides a parsimonious account of these adaptation effects.

  4. Adaptive Units of Learning and Educational Videogames

    Science.gov (United States)

    Moreno-Ger, Pablo; Thomas, Pilar Sancho; Martinez-Ortiz, Ivan; Sierra, Jose Luis; Fernandez-Manjon, Baltasar

    2007-01-01

    In this paper, we propose three different ways of using IMS Learning Design to support online adaptive learning modules that include educational videogames. The first approach relies on IMS LD to support adaptation procedures where the educational games are considered as Learning Objects. These games can be included instead of traditional content…

  5. STARS A Two Stage High Gain Harmonic Generation FEL Demonstrator

    Energy Technology Data Exchange (ETDEWEB)

    M. Abo-Bakr; W. Anders; J. Bahrdt; P. Budz; K.B. Buerkmann-Gehrlein; O. Dressler; H.A. Duerr; V. Duerr; W. Eberhardt; S. Eisebitt; J. Feikes; R. Follath; A. Gaupp; R. Goergen; K. Goldammer; S.C. Hessler; K. Holldack; E. Jaeschke; Thorsten Kamps; S. Klauke; J. Knobloch; O. Kugeler; B.C. Kuske; P. Kuske; A. Meseck; R. Mitzner; R. Mueller; M. Neeb; A. Neumann; K. Ott; D. Pfluckhahn; T. Quast; M. Scheer; Th. Schroeter; M. Schuster; F. Senf; G. Wuestefeld; D. Kramer; Frank Marhauser

    2007-08-01

    BESSY is proposing a demonstration facility, called STARS, for a two-stage high-gain harmonic generation free electron laser (HGHG FEL). STARS is planned for lasing in the wavelength range 40 to 70 nm, requiring a beam energy of 325 MeV. The facility consists of a normal conducting gun, three superconducting TESLA-type acceleration modules modified for CW operation, a single stage bunch compressor and finally a two-stage HGHG cascaded FEL. This paper describes the faciliy layout and the rationale behind the operation parameters.

  6. Laterally periodic resonator for large-area gain lasers.

    Science.gov (United States)

    Feng, Yan; Ueda, Ken-Ichi

    2003-03-24

    Laterally periodic resonators, which can be constructed by use of transversely periodic phase- or amplitude-modulating elements in a cavity, are proposed for stabilization and generation of transversely coherent output from large-area gain. Lasers with periodic resonators have the combined features of conventional cavities and laser arrays. Significant low-order transverse modes and mode discrimination of a sample resonator with intracavity periodic phase elements are investigated numerically by the iteration method. Wave-propagation calculations are carried out by use of a fast Fourier transform, and a modified Prony method is used to evaluate wave functions and losses of transverse modes. Results of numerical calculations are consistent with expectations.

  7. Performance Analysis of Blind Beamforming Algorithms in Adaptive Antenna Array in Rayleigh Fading Channel Model

    International Nuclear Information System (INIS)

    In this paper, we analyze the performance of adaptive blind algorithms – i.e. Kaiser Constant Modulus Algorithm (KCMA), Hamming CMA (HAMCMA) – with CMA in a wireless cellular communication system using digital modulation technique. These blind algorithms are used in digital signal processor of adaptive antenna to make it smart and change weights of the antenna array system dynamically. The simulation results revealed that KCMA and HAMCMA provide minimum mean square error (MSE) with 1.247 dB and 1.077 dB antenna gain enhancement, 75% reduction in bit error rate (BER) respectively over that of CMA. Therefore, KCMA and HAMCMA algorithms give a cost effective solution for a communication system

  8. Parity-time-antisymmetric atomic lattices without gain

    Science.gov (United States)

    Wu, Jin-Hui; Artoni, M.; La Rocca, G. C.

    2015-03-01

    Lossy atomic photonic crystals can be suitably tailored so that the real and imaginary parts of the susceptibility are, respectively, an odd and an even function of position. Such a parity-time (P T ) space antisymmetry in the susceptibility requires neither optical gain nor negative refraction, but is rather attained by a combined control of the spatial modulation of both the atomic density and their dynamic level shift. These passive photonic crystals made of dressed atoms are characterized by a tunable unidirectional reflectionlessness accompanied by an appreciable degree of transmission. Interestingly, such peculiar properties are associated with non-Hermitian degeneracies of the crystal scattering matrix, which can then be directly observed through reflectivity measurements via a straightforward phase modulation of the atomic dynamic level shift and even off resonance.

  9. Is adaptation. Truly an adaptation? Is adaptation. Truly an adaptation?

    Directory of Open Access Journals (Sweden)

    Thais Flores Nogueira Diniz

    2008-04-01

    Full Text Available The article begins by historicizing film adaptation from the arrival of cinema, pointing out the many theoretical approaches under which the process has been seen: from the concept of “the same story told in a different medium” to a comprehensible definition such as “the process through which works can be transformed, forming an intersection of textual surfaces, quotations, conflations and inversions of other texts”. To illustrate this new concept, the article discusses Spike Jonze’s film Adaptation. according to James Naremore’s proposal which considers the study of adaptation as part of a general theory of repetition, joined with the study of recycling, remaking, and every form of retelling. The film deals with the attempt by the scriptwriter Charles Kaufman, cast by Nicholas Cage, to adapt/translate a non-fictional book to the cinema, but ends up with a kind of film which is by no means what it intended to be: a film of action in the model of Hollywood productions. During the process of creation, Charles and his twin brother, Donald, undergo a series of adventures involving some real persons from the world of film, the author and the protagonist of the book, all of them turning into fictional characters in the film. In the film, adaptation then signifies something different from itstraditional meaning. The article begins by historicizing film adaptation from the arrival of cinema, pointing out the many theoretical approaches under which the process has been seen: from the concept of “the same story told in a different medium” to a comprehensible definition such as “the process through which works can be transformed, forming an intersection of textual surfaces, quotations, conflations and inversions of other texts”. To illustrate this new concept, the article discusses Spike Jonze’s film Adaptation. according to James Naremore’s proposal which considers the study of adaptation as part of a general theory of repetition

  10. MOS current gain cells with electronically variable gain and constant bandwidth

    NARCIS (Netherlands)

    Klumperink, Eric A.M.; Seevinck, Evert

    1989-01-01

    Two MOS current gain cells are proposed that provide linear amplification of currents supplied by several linear MOS V-I converters. The gain is electronically variable by a voltage or a current and can be made insensitive to temperature and IC processing. The gain cells have a constant (gain-indepe

  11. MOS current gain cells with electronically variable gain and constant bandwidth

    OpenAIRE

    Klumperink, Eric A.M.; Seevinck, Evert

    1989-01-01

    Two MOS current gain cells are proposed that provide linear amplification of currents supplied by several linear MOS V-I converters. The gain is electronically variable by a voltage or a current and can be made insensitive to temperature and IC processing. The gain cells have a constant (gain-independent) bandwidth

  12. Influences of finite gain bandwidth on pulse propagation in parabolic fiber amplifiers with distributed gain profiles

    Institute of Scientific and Technical Information of China (English)

    Zhao Jia-Sheng; Li Pan; Chen Xiao-Dong; Feng Su-Juan; Mao Qing-He

    2012-01-01

    The evolutions of the pulses propagating in decreasing and increasing gain distributed fiber amplifiers with finite gain bandwidths are investigated by simulations with the nonlinear Schrodinger equation.The results show that the parabolic pulse propagations in both the decreasing and the increasing gain amplifiers are restricted by the finite gain bandwidth.For a given input pulse,by choosing a small initial gain coefficient and gain variation rate,the whole gain for the pulse amplification limited by the gain bandwidth may be higher,which is helpful for the enhancement of the output linearly chirped pulse energy.Compared to the decreasing gain distributed fiber amplifier,the increasing gain distributed amplifier may be more conducive to suppress the pulse spectral broadening and increase the critical amplifier length for achieving a larger output linearly chirped pulse energy.

  13. Artificial emotion triggered stochastic behavior transitions with motivational gain effects for multi-objective robot tasks

    Science.gov (United States)

    Dağlarli, Evren; Temeltaş, Hakan

    2007-04-01

    This paper presents artificial emotional system based autonomous robot control architecture. Hidden Markov model developed as mathematical background for stochastic emotional and behavior transitions. Motivation module of architecture considered as behavioral gain effect generator for achieving multi-objective robot tasks. According to emotional and behavioral state transition probabilities, artificial emotions determine sequences of behaviors. Also motivational gain effects of proposed architecture can be observed on the executing behaviors during simulation.

  14. Sensory gain control (amplification) as a mechanism of selective attention: electrophysiological and neuroimaging evidence.

    OpenAIRE

    Hillyard, S. A.; Vogel, E K; Luck, S. J.

    1998-01-01

    Both physiological and behavioral studies have suggested that stimulus-driven neural activity in the sensory pathways can be modulated in amplitude during selective attention. Recordings of event-related brain potentials indicate that such sensory gain control or amplification processes play an important role in visual-spatial attention. Combined event-related brain potential and neuroimaging experiments provide strong evidence that attentional gain control operates at an early stage of visua...

  15. Random lasing with spatially nonuniform gain

    Science.gov (United States)

    Fan, Ting; Lü, Jiantao

    2016-07-01

    Spatial and spectral properties of random lasing with spatially nonuniform gain were investigated in two-dimensional (2D) disordered medium. The pumping light was described by an individual electric field and coupled into the rate equations by using the polarization equation. The spatially nonuniform gain comes from the multiple scattering of this pumping light. Numerical simulation of the random system with uniform and nonuniform gain were performed both in weak and strong scattering regime. In weak scattering sample, all the lasing modes correspond to those of the passive system whether the nonuniform gain is considered. However, in strong scattering regime, new lasing modes appear with nonuniform gain as the localization area changes. Our results show that it is more accurate to describe the random lasing behavior with introducing the nonuniform gain origins from the multiple light scattering.

  16. Gain Characteristics of Fiber Optical Parametric Amplifier

    Institute of Scientific and Technical Information of China (English)

    高明义; 姜淳; 胡卫生

    2004-01-01

    The theory model of fiber optical parametric amplifier (FOPA) was introduced, which is based on optical nonlinear effect. And then numerical simulation was done to analyze and discuss the gain spectral characteristics of one-pump and two-pump FOPA. The results show that for one-pump FOPA, when pump wavelength is near to fiber zero-dispersion wavelength(ZDW), the gain flatness is better, and with the increase of the pump power, fiber length and its nonlinear coefficient, the gain value will increase while the gain bandwidth will become narrow. For two-pump FOPA, when the pump central wavelength is near to fiber ZDW, the gain flatness is better. Moreover, by decreasing the space of two pumps wavelength, the gain flatness can be improved. Finally, some problems existing in FOPA were addressed.

  17. Measurement of Antenna Bore-Sight Gain

    Science.gov (United States)

    Fortinberry, Jarrod; Shumpert, Thomas H.

    2016-01-01

    The absolute or free-field gain of a simple antenna can be approximated using standard antenna theory formulae or for a more accurate prediction, numerical methods may be employed to solve for antenna parameters including gain. Both of these methods will result in relatively reasonable estimates but in practice antenna gain is usually verified and documented via measurements and calibration. In this paper, a relatively simple and low-cost, yet effective means of determining the bore-sight free-field gain of a VHF/UHF antenna is proposed by using the Brewster angle relationship.

  18. Energy Gaining Windows for Residental Buildings

    OpenAIRE

    Kragh, Jesper; Laustsen, Jacob Birck; Svendsen, Svend

    2008-01-01

    This paper presents some of the research done during the last 8 years at the Technical University of Denmark developing improved low-energy window solutions. The focus has been on maximizing the net energy gain of windows for residential buildings. The net energy gain of windows is the solar gain minus the heat loss integrated over the heating season. It is assumed that in northern cold climates all of the solar gain during the heating season can be utilized for space heating. Problems with o...

  19. Intelligent Communication Module for Wireless Biosensor Networks

    OpenAIRE

    Naik, R.; Singh, J.; Le, H. P.

    2010-01-01

    This chapter presented a new paradigm of biosensors which have processing capability with an intelligent and adaptive wireless communication module. The adaptive communication module efficiently reconfigures its hardware components according to the changes in operating environment in order to reduce system power consumption and optimally utilise resources. The chapter presented several significant applications of wireless biosensor networks which hold enormous potential to benefit the communi...

  20. Adaptive test

    DEFF Research Database (Denmark)

    Kjeldsen, Lars Peter; Eriksen, Mette Rose

    2010-01-01

    Artikelen er en evaluering af de adaptive tests, som blev indført i folkeskolen. Artiklen sætter særligt fokus på evaluering i folkeskolen, herunder bidrager den med vejledning til evaluering, evalueringsværktøjer og fagspecifkt evalueringsmateriale.......Artikelen er en evaluering af de adaptive tests, som blev indført i folkeskolen. Artiklen sætter særligt fokus på evaluering i folkeskolen, herunder bidrager den med vejledning til evaluering, evalueringsværktøjer og fagspecifkt evalueringsmateriale....

  1. Strategic Adaptation

    DEFF Research Database (Denmark)

    Andersen, Torben Juul

    2015-01-01

    This article provides an overview of theoretical contributions that have influenced the discourse around strategic adaptation including contingency perspectives, strategic fit reasoning, decision structure, information processing, corporate entrepreneurship, and strategy process. The related...... concepts of strategic renewal, dynamic managerial capabilities, dynamic capabilities, and strategic response capabilities are discussed and contextualized against strategic responsiveness. The insights derived from this article are used to outline the contours of a dynamic process of strategic adaptation....... This model incorporates elements of central strategizing, autonomous entrepreneurial behavior, interactive information processing, and open communication systems that enhance the organization's ability to observe exogenous changes and respond effectively to them....

  2. Adaptive management

    Science.gov (United States)

    Allen, Craig R.; Garmestani, Ahjond S.

    2015-01-01

    Adaptive management is an approach to natural resource management that emphasizes learning through management where knowledge is incomplete, and when, despite inherent uncertainty, managers and policymakers must act. Unlike a traditional trial and error approach, adaptive management has explicit structure, including a careful elucidation of goals, identification of alternative management objectives and hypotheses of causation, and procedures for the collection of data followed by evaluation and reiteration. The process is iterative, and serves to reduce uncertainty, build knowledge and improve management over time in a goal-oriented and structured process.

  3. MIMO Free-Space Optical Communication Employing Subcarrier Intensity Modulation in Atmospheric Turbulence Channels

    Science.gov (United States)

    Ghassemlooy, Zabih; Popoola, Wasiu O.; Ahmadi, Vahid; Leitgeb, Erich

    In this paper, we analyse the error performance of transmitter/receiver array free-space optical (FSO) communication system employing binary phase shift keying (BPSK) subcarrier intensity modulation (SIM) in clear but turbulent atmospheric channel. Subcarrier modulation is employed to eliminate the need for adaptive threshold detector. Direct detection is employed at the receiver and each subcarrier is subsequently demodulated coherently. The effect of irradiance fading is mitigated with an array of lasers and photodetectors. The received signals are linearly combined using the optimal maximum ratio combining (MRC), the equal gain combining (EGC) and the selection combining (SelC). The bit error rate (BER) equations are derived considering additive white Gaussian noise and log normal intensity fluctuations. This work is part of the EU COST actions and EU projects.

  4. Adaptive Effects on Locomotion Performance Following Exposure to a Rotating Virtual Environment

    Science.gov (United States)

    Mulavara, A. P.; Richards, J. T.; Marshburn, A. M.; Bucello, R.; Bloomberg, J. J.

    2003-01-01

    During long-duration spaceflight, astronauts experience alterations in vestibular and somatosensory cues that result in adaptive disturbances in balance and coordination upon return to Earth. These changes can pose a risk to crew safety and to mission objectives if nominal or emergency vehicle egress is required immediately following long-duration spaceflight. At present, no operational countermeasure is available to mitigate the adaptive sensorimotor component underlying the locomotor disturbances that occur after spaceflight. Therefore, the goal of this study is to develop an inflight training regimen that facilitates recovery of locomotor function after long-duration spaceflight. The countermeasure we are proposing is based on the concept of adaptive generalization. During this type of training the subject gains experience producing the appropriate adaptive motor behavior under a variety of sensory conditions and response constraints. As a result of this training a subject learns to solve a class of motor problems, rather than a specific motor solution to one problem, i.e., the subject learns response generalizability or the ability to "learn to learn." under a variety of environmental constraints. We are developing an inflight countermeasure built around treadmill exercise activities. By manipulating the sensory conditions of exercise by varying visual flow patterns, body load and speed we will systematically and repeatedly promote adaptive change in locomotor behavior. It has been shown that variable practice training increases adaptability to novel visuo-motor situations. While walking over ground in a stereoscopic virtual environment that oscillated in roll, subjects have shown compensatory torso rotation in the direction of scene rotation that resulted in positional variation away from a desired linear path. Thus, postural sway and locomotor stability in 1-g can be modulated by visual flow patterns and used during inflight treadmill training to promote

  5. Dynamic Gain-Clamped Amplifier with Backward-Injection of a Fabry-Perot Laser

    Institute of Scientific and Technical Information of China (English)

    Chien-Hung; Yeh; Chih-Yang; Chen; Chien-Chung; Lee; Sien; Chi

    2003-01-01

    We have been experimentally demonstrated an active control technique of dynamic gain-clamped spectra for theerbium-doped fiber amplifiers (EDFA's) by a backward-injected Fabry-Perot (F-P) laser into this EDFA. In addition, employing a short length erbium-doped fiber (EDF) that not cause any gain saturation for preamplification in front of this amplifier module, it can reduce the noise figure degradation and simultaneously achieve gain variation from 11.1 dB to 0.5 dB for 10 dB input power level change.

  6. An Algorithm for Quantitatively Calculating I/Q Gain and Phase Mismatch

    Directory of Open Access Journals (Sweden)

    Jin Liu

    2012-08-01

    Full Text Available The in-phase and quadrature modulator (IQ modulator is a key component in modern wireless transmitter. It provides a convenient method for modulating data bits or symbols onto an RF carrier. It has become the architecture of choice for implementing transmitter signal chains for end applications such as cellular, WiMAX, and wireless point-to-point. However, there are several non-ideal aspects of analog IQ modulator, include IQ gain imbalance, imperfect quadrature, and LO leakage. These imperfections will result in image spectral and degrade MER of the modulator, which in turn degrades bit error rate (BER. Gain matching and phase compensation both affect the total amount of image rejection. Factory calibration can detect the IQ gain and phase mismatch in different frequency and store the correction coefficients in nonvolatile memory. The key issue is how to get the exact mismatch. In this paper, a mathematical model of IQ modulator was established and an analytic solution is obtained about how to get the exact mismatch parameters.

  7. Pump-To-Signal Intensity Modulation Transfer Characteristics in FOPAs: Modulation Frequency and Saturation Effect

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Cristofori, Valentina; Lund-Hansen, Toke;

    2012-01-01

    This paper reports a comprehensive study of pump- to-signal intensity modulation transfer (IMT) in single-pump fiber optic parametric amplifiers (FOPAs). In particular, the IMT is studied for the first time for high-frequency fluctuations of the pump as well as in the saturated gain regime. The IMT......% in the gain saturation regime with respect to the linear gain operation. Experimental results confirm the validity of the numerical study....

  8. Maximum gain of Yagi-Uda arrays

    DEFF Research Database (Denmark)

    Bojsen, J.H.; Schjær-Jacobsen, Hans; Nilsson, E.;

    1971-01-01

    Numerical optimisation techniques have been used to find the maximum gain of some specific parasitic arrays. The gain of an array of infinitely thin, equispaced dipoles loaded with arbitrary reactances has been optimised. The results show that standard travelling-wave design methods are not optimum....... Yagi–Uda arrays with equal and unequal spacing have also been optimised with experimental verification....

  9. Gain Shift Corrections at Chi-Nu

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Tristan Brooks [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Massachusetts, Lowell, MA (United States). Dept. of Physics and Applied Physics; Devlin, Matthew James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-30

    Ambient conditions have the potential to cause changes in liquid scintillator detector gain that vary with time and temperature. These gain shifts can lead to poor resolution in both energy as well as pulse shape discrimination. In order to correct for these shifts in the Chi-Nu high energy array, a laser system has been developed for calibration of the pulse height signals.

  10. Gaining Mindshare and Timeshare : Marketing Public Libraries

    OpenAIRE

    Paul, Johnson; Kua, Lena; Narayanan, N. Varaprasad

    2005-01-01

    This presentation is an examination of how the National Library Board had successfully gained market share by redefining its market space and remaking the image of libraries and librarians. Libraries were repositioned to gain mindshare and timeshare among Singaporeans, competing against the cinema, TV, video games and other leisure activities, becoming the Third Place after home and work for many.

  11. Detailed Theoretical Model for Adjustable Gain-Clamped Semiconductor Optical Amplifier

    Directory of Open Access Journals (Sweden)

    Lin Liu

    2012-01-01

    Full Text Available The adjustable gain-clamped semiconductor optical amplifier (AGC-SOA uses two SOAs in a ring-cavity topology: one to amplify the signal and the other to control the gain. The device was designed to maximize the output saturated power while adjusting gain to regulate power differences between packets without loss of linearity. This type of subsystem can be used for power equalisation and linear amplification in packet-based dynamic systems such as passive optical networks (PONs. A detailed theoretical model is presented in this paper to simulate the operation of the AGC-SOA, which gives a better understanding of the underlying gain clamping mechanics. Simulations and comparisons with steady-state and dynamic gain modulation experimental performance are given which validate the model.

  12. Dwell scheduling algorithm for multifunction phased array radars based on the scheduling gain

    Institute of Scientific and Technical Information of China (English)

    Cheng Ting; He Zishu; Tang Ting

    2008-01-01

    A real-time dwell scheduling model, which takes the time and energy constraints into account is founded from the viewpoint of scheduling gain. Scheduling design is turned into a nonlinear programming procedure. The real-time dwell scheduling algorithm based on the scheduling gain is presented with the help of two heuristic rules. The simulation results demonstrate that compared with the conventional adaptive scheduling method, the algorithm proposed not only increases the scheduling gain and the time utility but also decreases the task drop rate.

  13. Energy Gaining Windows for Residental Buildings

    DEFF Research Database (Denmark)

    Kragh, Jesper; Laustsen, Jacob Birck; Svendsen, Svend

    This paper presents some of the research done during the last 8 years at the Technical University of Denmark developing improved low-energy window solutions. The focus has been on maximizing the net energy gain of windows for residential buildings. The net energy gain of windows is the solar gain...... windows have already been developed and prototypes constructed for laboratory test and a third generation of the window design is now in the developing and designing face in a new project. The first window constructed was made of wood profiles and a low-energy double glazing unit. The second and third...... and longer durability of the window. The glazing in these fiber reinforced polyester windows is both unsealed and sealed triple glazing units. To increase the net energy gain slim frame profiles have been developed to increase the glazing area and thereby the solar gain. The challenge when developing slim...

  14. Undergraduate Urban Metagenomics Research Module

    OpenAIRE

    Muth, Theodore R.; McEntee, Catherine M.

    2014-01-01

    The undergraduate urban metagenomics research module is an adaptable and tractable project that can be incorporated into exisiting microbiology, ecology, bioinformatics, introductory biology or other courses.  The module takes advantage of recent advances in metagenomics and next generation sequencing, giving students an opportunity to apply these current technologies to novel questions regarding microbial community diversity and dynamics.

  15. 某型雷达板级模块测试适配器的设计与实现%Design and Implementation of a radar board-level module testing adapter

    Institute of Scientific and Technical Information of China (English)

    郭锐

    2015-01-01

    某型雷达电路板测试适配器需要对二十多种电路板进行功能测试,被测电路板信号时序复杂,接口定义不统一,给适配器设计带来困难。本文采用通用适配器设计方案成功的解决了问题,实践证明,该适配器设计灵活,大大简化多电路板检测适配器的设计难度,具有一定的工程借鉴价值。%A radar circuit board test adapter requires two dozen board functional test, the measured signal timing circuit board complexity, the interface definition is not uniform, to the adapter design difficult. In this paper, universal adapter design successfully solved the problem, proved that the adapter is designed to be flexible, which greatly simplifies testing circuit boards and multi-adapter design difficulty, with some engineering reference value.

  16. A Model for Dynamic Adaptive Coscheduling

    Institute of Scientific and Technical Information of China (English)

    LU Sanglu; ZHOU Xiaobo; XIE Li

    1999-01-01

    This paper proposes a dynamic adaptive coscheduling modelDASIC to take advantage of excess available resources in anetwork of workstations (NOW). Besides coscheduling related subtasksdynamically, DASIC can scale up or down the process space dependingupon the number of available processors on an NOW. Based on thedynamic idle processor group (IPG), DASIC employs three modules: thecoscheduling module, the scalable scheduling module and the loadbalancing module, and uses six algorithms to achieve scalability. Asimplified DASIC was also implemented, and experimental results arepresented in this paper, which show that it can maximize systemutilization, and achieve task parallelism as much as possible.

  17. Adaptation Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Huq, Saleemul

    2011-11-15

    Efforts to help the world's poor will face crises in coming decades as climate change radically alters conditions. Action Research for Community Adapation in Bangladesh (ARCAB) is an action-research programme on responding to climate change impacts through community-based adaptation. Set in Bangladesh at 20 sites that are vulnerable to floods, droughts, cyclones and sea level rise, ARCAB will follow impacts and adaptation as they evolve over half a century or more. National and international 'research partners', collaborating with ten NGO 'action partners' with global reach, seek knowledge and solutions applicable worldwide. After a year setting up ARCAB, we share lessons on the programme's design and move into our first research cycle.

  18. Adaptive ethnography

    DEFF Research Database (Denmark)

    Berth, Mette

    2005-01-01

    This paper focuses on the use of an adaptive ethnography when studying such phenomena as young people's use of mobile media in a learning perspective. Mobile media such as PDAs and mobile phones have a number of affordances which make them potential tools for learning. However, before we begin...... formal and informal learning contexts. The paper also proposes several adaptive methodological techniques for studying young people's interaction with mobiles....... to design and develop educational materials for mobile media platforms we must first understand everyday use and behaviour with a medium such as a mobile phone. The paper outlines the research design for a PhD project on mobile learning which focuses on mobile phones as a way to bridge the gap between...

  19. Hedonic "adaptation"

    Directory of Open Access Journals (Sweden)

    Paul Rozin

    2008-02-01

    Full Text Available People live in a world in which they are surrounded by potential disgust elicitors such as ``used'' chairs, air, silverware, and money as well as excretory activities. People function in this world by ignoring most of these, by active avoidance, reframing, or adaptation. The issue is particularly striking for professions, such as morticians, surgeons, or sanitation workers, in which there is frequent contact with major disgust elicitors. In this study, we study the ``adaptation'' process to dead bodies as disgust elicitors, by measuring specific types of disgust sensitivity in medical students before and after they have spent a few months dissecting a cadaver. Using the Disgust Scale, we find a significant reduction in disgust responses to death and body envelope violation elicitors, but no significant change in any other specific type of disgust. There is a clear reduction in discomfort at touching a cold dead body, but not in touching a human body which is still warm after death.

  20. Adaptive noise

    OpenAIRE

    Viney, Mark; Reece, Sarah E.

    2013-01-01

    In biology, noise implies error and disorder and is therefore something which organisms may seek to minimize and mitigate against. We argue that such noise can be adaptive. Recent studies have shown that gene expression can be noisy, noise can be genetically controlled, genes and gene networks vary in how noisy they are and noise generates phenotypic differences among genetically identical cells. Such phenotypic differences can have fitness benefits, suggesting that evolution can shape noise ...

  1. Adaptable positioner

    International Nuclear Information System (INIS)

    This paper describes the circuits and programs in assembly language, developed to control the two DC motors that give mobility to a mechanical arm with two degrees of freedom. As a whole, the system is based in a adaptable regulator designed around a 8 bit microprocessor that, starting from a mode of regulation based in the successive approximation method, evolve to another mode through which, only one approximation is sufficient to get the right position of each motor. (Author) 22 fig. 6 ref

  2. An Overview of the Adaptive Robust DFT

    Directory of Open Access Journals (Sweden)

    Djurović Igor

    2010-01-01

    Full Text Available Abstract This paper overviews basic principles and applications of the robust DFT (RDFT approach, which is used for robust processing of frequency-modulated (FM signals embedded in non-Gaussian heavy-tailed noise. In particular, we concentrate on the spectral analysis and filtering of signals corrupted by impulsive distortions using adaptive and nonadaptive robust estimators. Several adaptive estimators of location parameter are considered, and it is shown that their application is preferable with respect to non-adaptive counterparts. This fact is demonstrated by efficiency comparison of adaptive and nonadaptive RDFT methods for different noise environments.

  3. TCAD simulation of Low Gain Avalanche Detectors

    Science.gov (United States)

    Dalal, Ranjeet; Jain, Geetika; Bhardwaj, Ashutosh; Ranjan, Kirti

    2016-11-01

    In the present work, detailed simulation using Technology Computer Aided Design (TCAD) tool, Silvaco for non-irradiated and irradiated LGAD (Low Gain Avalanche Detector) devices has been carried out. The effects of different design parameters and proton irradiation on LGAD operation are discussed in detail. An already published effective two trap bulk damage model is used to simulate the radiation damage without implementing any acceptor removal term. The TCAD simulation for irradiated LGAD devices produce decreasing gain with increasing fluence, similar to the measurement results. The space charge density and electric field distribution are used to illustrate the possible reasons for the degradation of gain of the irradiated LGAD devices.

  4. Nonunity gain minimal-disturbance measurement

    DEFF Research Database (Denmark)

    Sabuncu, Metin; Mišta, L.; Fiurášek, J.;

    2007-01-01

    We propose and experimentally demonstrate an optimal nonunity gain Gaussian scheme for partial measurement of an unknown coherent state that causes minimal disturbance of the state. The information gain and the state disturbance are quantified by the noise added to the measurement outcomes...... and to the output state, respectively. We derive the optimal trade-off relation between the two noises and we show that the tradeoff is saturated by nonunity gain teleportation. Optimal partial measurement is demonstrated experimentally using a linear optics scheme with feedforward....

  5. Tracking Neural Modulation Depth by Dual Sequential Monte Carlo Estimation on Point Processes for Brain-Machine Interfaces.

    Science.gov (United States)

    Wang, Yiwen; She, Xiwei; Liao, Yuxi; Li, Hongbao; Zhang, Qiaosheng; Zhang, Shaomin; Zheng, Xiaoxiang; Principe, Jose

    2016-08-01

    Classic brain-machine interface (BMI) approaches decode neural signals from the brain responsible for achieving specific motor movements, which subsequently command prosthetic devices. Brain activities adaptively change during the control of the neuroprosthesis in BMIs, where the alteration of the preferred direction and the modulation of the gain depth are observed. The static neural tuning models have been limited by fixed codes, resulting in a decay of decoding performance over the course of the movement and subsequent instability in motor performance. To achieve stable performance, we propose a dual sequential Monte Carlo adaptive point process method, which models and decodes the gradually changing modulation depth of individual neuron over the course of a movement. We use multichannel neural spike trains from the primary motor cortex of a monkey trained to perform a target pursuit task using a joystick. Our results show that our computational approach successfully tracks the neural modulation depth over time with better goodness-of-fit than classic static neural tuning models, resulting in smaller errors between the true kinematics and the estimations in both simulated and real data. Our novel decoding approach suggests that the brain may employ such strategies to achieve stable motor output, i.e., plastic neural tuning is a feature of neural systems. BMI users may benefit from this adaptive algorithm to achieve more complex and controlled movement outcomes. PMID:26584486

  6. Rapid Adaptation in Digital Transformation

    DEFF Research Database (Denmark)

    Hansen, Anne Mette; Kræmmergaard, Pernille; Mathiassen, Lars

    2011-01-01

    In today’s highly dynamic environments, organizational leaders need to quickly adapt existing approaches to digital transformation. However, without a shared mindset between IS and business leaders, it is difficult to adopt new approaches in response to changes in the competitive and technology...... landscape. In this article, we share insights gained from two public sector organizations in which IS and business leaders used the Participatory Process Model (PPM) designed by the authors to share their assumptions about IS leadership, challenge existing IT strategies and collaboration patterns and adapt...... the organization’s digitization approach. We demonstrate in detail how the leaders within these two organizations were engaged and offer recommendations for how other organizations can use the PPM to rapidly adapt their approaches to digital transformation through more effective IS leadership roles....

  7. Kids Gain from More 'Dad Time'

    Science.gov (United States)

    ... fullstory_159341.html Kids Gain From More 'Dad Time' Pediatricians' report details the many benefits To use ... children's development, a new report shows. Just in time for Father's Day, the American Academy of Pediatrics ...

  8. Gain Stabilization of SiPMs

    CERN Document Server

    Cvach, Jaroslav; Kvasnicka, Jiri; Polak, Ivo; van der Kraiij, Erik; Zalieckas, Justas

    2014-01-01

    The gain of SiPMs depends both on bias voltage and on temperature. For stable operations, both need to be kept constant. In an ILC calorimeter with millions of channels, this is a challenging task. It is, therefore, desirable to compensate for temperature variations by automatically readjusting the bias voltage. We have designed a bias voltage regulator board to achieve this task. We anticipate an uncertainty on the gain stability at the level of $< 1\\%$. First, we present measurements of the gain dependence on temperature and bias voltage for several SiPMs from three different manufacturers and determine their dV/dT dependence. Next, we demonstrate the performance of the gain stability with the bias voltage regulator test board on four SiPMs.

  9. Transient optical gain in germanium quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, Sangam; Lange, Christoph; Koester, Niko S.; Schaefer, Martin; Kira, Mackillo; Koch, Stephan W. [Faculty of Physics and Materials Sciences Center, Philipps-Universitaet Marburg (Germany); Chrastina, Daniel; Isella, Giovanni; Kaenel, Hans von [CNISM, Como (Italy); L-NESS, Dipartimento di Fisica del Politecnico di Milano, Como (Italy); Sigg, Hans [Laboratory for Micro and Nanotecnology, Paul Scherrer Institut, Villigen PSI (Switzerland)

    2010-07-01

    One of today's most-sought goals in semiconductor technology is the monolithic integration of microelectronics and photonics on Si. Optical gain is, in general, not expected for Si and Ge or its alloys due to the indirect nature of the band gap in this material system. Here, we show that Ge/SiGe QWs show transient optical gain and may thus be used as an optically-pumped amplifier at room temperature. Further, the nonequilibrium effects which govern the relaxation dynamics of the optically injected carrier distributions in this material were observed and analyzed using a microscopic many-body theory. Strong non-equilibrium gain was obtained on a sub-100 fs time scale. Long-lived gain arising from {gamma}-point transitions is overcompensated by a process bearing the character of free carrier absorption.

  10. Optical properties of nanowire metamaterials with gain

    DEFF Research Database (Denmark)

    Isidio de Lima, Joaquim Junior; Adam, Jost; Rego, Davi;

    2016-01-01

    The transmittance, reflectance and absorption of a nanowire metamaterial with optical gain are numerically simulated and investigated. It is assumed that the metamaterial is represented by aligned silver nanowires embedded into a semiconductor matrix, made of either silicon or gallium phosphide....... The gain in the matrix is modeled by adding a negative imaginary part to the dielectric function of the semiconductor. It is found that the optical coefficients of the metamaterial depend on the gain magnitude in a non-trivial way: they can both increase and decrease with gain depending on the lattice...... constant of the metamaterial. This peculiar behavior is explained by the field redistribution between the lossy metal nanowires and the amplifying matrix material. These findings are significant for a proper design of nanowire metamaterials with low optical losses for diverse applications....

  11. Active Microwave Metamaterials Incorporating Ideal Gain Devices

    Directory of Open Access Journals (Sweden)

    Hao Xin

    2010-12-01

    Full Text Available Incorporation of active devices/media such as transistors for microwave and gain media for optics may be very attractive for enabling desired low loss and broadband metamaterials. Such metamaterials can even have gain which may very well lead to new and exciting physical phenomena. We investigate microwave composite right/left-handed transmission lines (CRLH-TL incorporating ideal gain devices such as constant negative resistance. With realistic lumped element values, we have shown that the negative phase constant of this kind of transmission lines is maintained (i.e., left-handedness kept while gain can be obtained (negative attenuation constant of transmission line simultaneously. Possible implementation and challenging issues of the proposed active CRLH-TL are also discussed.

  12. Optical properties of nanowire metamaterials with gain

    Science.gov (United States)

    Lima, Joaquim; Adam, Jost; Rego, Davi; Esquerre, Vitaly; Bordo, Vladimir

    2016-11-01

    The transmittance, reflectance and absorption of a nanowire metamaterial with optical gain are numerically simulated and investigated. It is assumed that the metamaterial is represented by aligned silver nanowires embedded into a semiconductor matrix, made of either silicon or gallium phosphide. The gain in the matrix is modeled by adding a negative imaginary part to the dielectric function of the semiconductor. It is found that the optical coefficients of the metamaterial depend on the gain magnitude in a non-trivial way: they can both increase and decrease with gain depending on the lattice constant of the metamaterial. This peculiar behavior is explained by the field redistribution between the lossy metal nanowires and the amplifying matrix material. These findings are significant for a proper design of nanowire metamaterials with low optical losses for diverse applications.

  13. Energy intake and energy expenditure for determining excess weight gain in pregnant women

    Science.gov (United States)

    To conduct a secondary analysis designed to test whether gestational weight gain is the result of increased energy intake or adaptive changes in energy expenditures. In this secondary analysis, energy intake and energy expenditure of 45 pregnant women (body mass index [BMI] 18.5-24.9 [n=33] and BMI ...

  14. Graphene as Gain Medium for Broadband Lasers

    OpenAIRE

    Jago, Roland; Winzer, T.; Knorr, A.; Malic, Ermin

    2014-01-01

    Efficient nonradiative carrier recombination strongly counteracts the appearance of optical gain in graphene. Based on a microscopic and fully quantum-mechanical study of the coupled carrier, phonon, and photon dynamics in graphene, we present a strategy to obtain a long-lived gain: Integrating graphene into a high quality photonic crystal nanocavity and applying a high-dielectric substrate suppresses the nonradiative recombination channels and gives rise to pronounced coherent light emission...

  15. Productive coexistence and gain in agroforestry systems.

    OpenAIRE

    Huang, Wending

    1998-01-01

    Productive coexistence and coexistence gain of populations were studied using nine years' data from field experiments of Taxodium ascendens-intercrop systems in Lixiahe, Jiangsu Province, China. A theoretical framework for productive coexistence in agroforestry was developed. Interaction patterns between trees and intercrops were presented within this framework. A model framework was developed to describe the coexistence gain and interaction of populations in T. ascendens-intercrop systems. F...

  16. Abuse history and nonoptimal prenatal weight gain.

    OpenAIRE

    Johnson, Pamela Jo; Hellerstedt, Wendy L.; Pirie, Phyllis L.

    2002-01-01

    OBJECTIVE: The purpose of this study was to examine the differences between women who reported current and past physical or sexual abuse and those who did not in terms of mean total prenatal weight change, the odds for inadequate prenatal gain, and the odds for excessive prenatal gain. METHODS: This study used a matched retrospective cohort design. Data were from the charts of 578 clients of an urban prenatal care clinic. Multiple regression analyses, stratified by maternal age, were conducte...

  17. Enhanced Gain in Photonic Crystal Amplifiers

    DEFF Research Database (Denmark)

    Ek, Sara; Semenova, Elizaveta; Hansen, Per Lunnemann;

    2012-01-01

    study of a 1 QW photonic crystal amplifier. Net gain is achieved which enables laser oscillation in photonic crystal micro cavities. The ability to freely tailor the dispersion in a semiconductor optical amplifier makes it possible to raise the optical gain considerably over a certain bandwidth. These...... results are promising for short and efficient semiconductor optical amplifiers. This effect will also benefit other devices, such as mode locked lasers....

  18. Solitons supported by localized parametric gain

    OpenAIRE

    Ye, Fangwei; HUANG, CHANGMING; Kartashov, Yaroslav V.; Malomed, Boris A.

    2013-01-01

    We address the existence and properties of one-dimensional solitons maintained by localized parameter gain in focusing and defocusing lossy nonlinear media. Localized parametric gain supports both fundamental and multipole solitons. We found that the family of fundamental solitons is partly stable in focusing nonlinear medium, and completely stable in defocusing medium, while all higher-order solitons are unstable. In addition to numerical results, the existence threshold for the solitons, an...

  19. MODELING THE ADAPTION RULE IN CONTEXTAWARE SYSTEMS

    Directory of Open Access Journals (Sweden)

    Mao Zheng

    2016-08-01

    Full Text Available Context awareness is increasingly gaining applicability in interactive ubiquitous mobile computing systems. Each context-aware application has its own set of behaviors to react to context modifications. This paper is concerned with the context modeling and the development methodology for context-aware systems. We proposed a rule-based approach and use the adaption tree to model the adaption rule of context-aware systems. We illustrate this idea in an arithmetic game application.

  20. Irreducible Specht modules are signed Young modules

    OpenAIRE

    Hemmer, David J.

    2005-01-01

    Recently Donkin defined signed Young modules as a simultaneous generalization of Young and twisted Young modules for the symmetric group. We show that in odd characteristic, if a Specht module $S^\\lambda$ is irreducible, then $S^\\lambda$ is a signed Young module. Thus the set of irreducible Specht modules coincides with the set of irreducible signed Young modules. This provides evidence for our conjecture that the signed Young modules are precisely the class of indecomposable self-dual module...

  1. FEL gain optimisation and spontaneous radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bali, L.M.; Srivastava, A.; Pandya, T.P. [Lucknow Univ. (India)] [and others

    1995-12-31

    Colson have evaluated FEL gains for small deviations from perfect electron beam injection, with radiation of the same polarisation as that of the wiggler fields. We find that for optimum gain the polarisation of the optical field should be the same as that of the spontaneous emission under these conditions. With a helical wiggler the axial oscillations resulting from small departures from perfect electron beam injection lead to injection dependent unequal amplitudes and phases of the spontaneous radiation in the two transverse directions. Viewed along the axis therefore the spontaneous emission is elliptically polarised. The azimuth of the ellipse varies with the difference of phase of the two transverse components of spontaneous emission but the eccentricity remains the same. With planar wigglers the spontaneous emission viewed in the axial direction is linearly polarised, again with an injection dependent azimuth. For optimum coherent gain of a radiation field its polarisation characteristics must be the same as those of the spontaneous radiation with both types of wiggler. Thus, with a helical wiggler and the data reported earlier, an increase of 10% in the FEL gain at the fundamental frequency and of 11% at the fifth harmonic has been calculated in the small gain per pass limit. Larger enhancements in gain may result from more favourable values of input parameters.

  2. Modulated desynchronism in a free-electron laser oscillator

    CERN Document Server

    Calderón, O G; Smith, T I

    2001-01-01

    We study experimentally and theoretically, the effects of desynchronism modulation on short pulse free-electron laser (FEL) oscillators. We find that the output power and the micropulse length of the FEL beam oscillate periodically at the modulation frequency and the minimum micropulse length can be significantly shorter than that obtained without modulation. The FEL can operate during part of the modulation cycle in the normally inaccessible portion of the output power curve where the FEL gain is less than the cavity loss.

  3. Rapid brain responses independently predict gain maximization and loss minimization during economic decision making.

    Science.gov (United States)

    San Martín, René; Appelbaum, Lawrence G; Pearson, John M; Huettel, Scott A; Woldorff, Marty G

    2013-04-17

    Success in many decision-making scenarios depends on the ability to maximize gains and minimize losses. Even if an agent knows which cues lead to gains and which lead to losses, that agent could still make choices yielding suboptimal rewards. Here, by analyzing event-related potentials (ERPs) recorded in humans during a probabilistic gambling task, we show that individuals' behavioral tendencies to maximize gains and to minimize losses are associated with their ERP responses to the receipt of those gains and losses, respectively. We focused our analyses on ERP signals that predict behavioral adjustment: the frontocentral feedback-related negativity (FRN) and two P300 (P3) subcomponents, the frontocentral P3a and the parietal P3b. We found that, across participants, gain maximization was predicted by differences in amplitude of the P3b for suboptimal versus optimal gains (i.e., P3b amplitude difference between the least good and the best gains). Conversely, loss minimization was predicted by differences in the P3b amplitude to suboptimal versus optimal losses (i.e., difference between the worst and the least bad losses). Finally, we observed that the P3a and P3b, but not the FRN, predicted behavioral adjustment on subsequent trials, suggesting a specific adaptive mechanism by which prior experience may alter ensuing behavior. These findings indicate that individual differences in gain maximization and loss minimization are linked to individual differences in rapid neural responses to monetary outcomes.

  4. Solar Module Fabrication

    Directory of Open Access Journals (Sweden)

    A. El Amrani

    2007-04-01

    Full Text Available One of the most important steps in the photovoltaic industry is the encapsulation of the solar cells. It consists to connect the cells in order to provide useful power for any application and also protect them from environmental damages which cause corrosion, and mechanical shocks. In this paper, we present the encapsulation process we have developed at Silicon Technology Unit (UDTS for monocrystalline silicon solar cells. We will focus particularly on the thermal treatment, the most critical step in the process, which decides on the quality and the reliability of the module. This thermal treatment is conducted in two steps: the lamination and the polymerization. Several tests of EVA reticulation have been necessary for setting technological parameters such as the level of vacuum, the pressure, the temperature, and the time. The quality of our process has been confirmed by the tests conducted on our modules at the European Laboratory of Joint Research Centre (JRC of ISPRA (Italy. The electrical characterization of the modules has showed that after the encapsulation the current has been improved by a factor of 4% to 6% and the power gain by a factor of 4% to 7%. This is mainly due to the fact of using a treated glass, which reduces the reflection of the light at a level as low as 8%.

  5. *-Modules, co-*-modules and cotilting modules over Noetherian rings

    Institute of Scientific and Technical Information of China (English)

    汪明义; 许永华

    1996-01-01

    Let R be a Noetherian ring. The projectivity and injectivity of modules over R are discussed. The concept of modules is introduced and the descriptions for co-*-modules over R are given. At last, cotilting modules over R are characterized by means of co-*-modules.

  6. Adaptive Radiation for Lung Cancer

    Directory of Open Access Journals (Sweden)

    Daniel R. Gomez

    2011-01-01

    need to spare surrounding critical structures. Evolving radiotherapy technologies, such as four-dimensional (4D image-based motion management, daily on-board imaging and adaptive radiotherapy based on volumetric images over the course of radiotherapy, have enabled us to deliver higher dose to target while minimizing normal tissue toxicities. The image-guided radiotherapy adapted to changes of motion and anatomy has made the radiotherapy more precise and allowed ablative dose delivered to the target using novel treatment approaches such as intensity-modulated radiation therapy, stereotactic body radiation therapy, and proton therapy in lung cancer, techniques used to be considered very sensitive to motion change. Future clinical trials using real time tracking and biological adaptive radiotherapy based on functional images are proposed.

  7. Mechanisms of strength gain in a handgrip exercise programme in rheumatoid arthritis.

    Science.gov (United States)

    Speed, C A; Campbell, R

    2012-01-01

    In a progressive resistive strengthening programme, healthy individuals gain strength initially through neural adaptation followed by increases in muscle mass. Programmes are designed to maximise these responses. The physiological mechanisms of strength gain in RA are unknown, but their identification will help to develop more effective exercise programmes. The aim of this study was to investigate the responses to a 12-week isometric handgrip strengthening programme in female subjects with RA. Fourteen right-handed female subjects with RA and 14 age-matched female controls participated in a 12-week right handgrip strengthening programme. Maximum grip strength (MGS) and disease activity were measured serially over 12 weeks. Forearm muscle volume was measured using MRI at baseline and 12 weeks. Significant gains in right handgrip strength were noted in both groups, the gains being most marked in those with RA: mean (SD; range) MGS (mmHg) in RA group at baseline 105.1 (48.1; 34-108) and 174.8 (76.4; 50-340) at 12 weeks. Mean (SD; range) MGS in control group at baseline 311.7 (49.6; 220-370) and 357.0 (67.1; 250-540) at 12 weeks. Significant increases in forearm muscle volume occurred in the controls, correlating with gains in strength. No such changes were noted in the RA group, indicating that improvements were solely related to neural adaptation. Response to strength training in RA differs from those of healthy individuals. Significant gains in strength in individuals with RA can occur due to neural adaptation without gains in muscle mass during a strengthening programme. This has implications for the design of rehabilitation programmes for such subjects.

  8. Seasonal Variations of Cell Site Diversity Gain

    Directory of Open Access Journals (Sweden)

    Sharmini Enoch

    2016-08-01

    Full Text Available The broadband fixed wireless access (BFWA systems operate in microwave frequencies. In this frequency range, the wave propagation is highly influenced by precipitation caused especially by rain. With the use of cell site diversity (CSD, the rain attenuation effects can be mitigated. When the signal level falls below a certain threshold the subscriber station switches to another base station within the coverage area. This paper aims at demonstrating the performance improvements obtained with the use of cell site diversity during various seasons for measurements carried out from HYREX rain gauge network in UK. The parameters traditionally used to quantify cell site diversity are CSD gain and diversity improvement. This paper analyzes the CSD gain achieved. The gain increases with increasing frequency and distance. The link performance is compared for various seasons and the results show that the maximum attenuation occurs during summer, while the least attenuation occurs during winter. Therefore, maximum gain of up to 22 dB occurs at 54 GHz frequency during winter. The second observation is that when the angular separation between the diversity sites is 180° separation there is maximum gain for all seasons.

  9. Modeling of a Multiple Digital Automatic Gain Control System

    Institute of Scientific and Technical Information of China (English)

    WANG Jingdian; LU Xiuhong; ZHANG Li

    2008-01-01

    Automatic gain control (AGC) has been used in many applications. The key features of AGC, including a steady state output and static/dynamic timing response, depend mainly on key parameters such as the reference and the filter coefficients. A simple model developed to describe AGC systems based on several simple assumptions shows that AGC always converges to the reference and that the timing constant depends on the filter coefficients. Measures are given to prevent oscillations and limit cycle effects. The simple AGC system is adapted to a multiple AGC system for a TV tuner in a much more efficient model. Simulations using the C language are 16 times faster than those with MATLAB, and 10 times faster than those with a mixed register transfer level (RTL)-simulation program with integrated circuit emphasis (SPICE) model.

  10. Adaptive management

    DEFF Research Database (Denmark)

    Rist, Lucy; Campbell, Bruce Morgan; Frost, Peter

    2013-01-01

    in scientific articles, policy documents and management plans, but both understanding and application of the concept is mixed. This paper reviews recent literature from conservation and natural resource management journals to assess diversity in how the term is used, highlight ambiguities and consider how...... a management framework, as well as of identified challenges and pathologies, are needed. Further discussion and systematic assessment of the approach is required, together with greater attention to its definition and description, enabling the assessment of new approaches to managing uncertainty, and AM itself.......Adaptive management (AM) emerged in the literature in the mid-1970s in response both to a realization of the extent of uncertainty involved in management, and a frustration with attempts to use modelling to integrate knowledge and make predictions. The term has since become increasingly widely used...

  11. Signed Young Modules and Simple Specht Modules

    OpenAIRE

    Danz, Susanne; Lim, Kay Jin

    2015-01-01

    By a result of Hemmer, every simple Specht module of a finite symmetric group over a field of odd characteristic is a signed Young module. While Specht modules are parametrized by partitions, indecomposable signed Young modules are parametrized by certain pairs of partitions. The main result of this article establishes the signed Young module labels of simple Specht modules. Along the way we prove a number of results concerning indecomposable signed Young modules that are of independent inter...

  12. Loss-Gain Equalized Reconfigurable Phaser for Dynamic Radio Analog Signal Processing (R-ASP)

    CERN Document Server

    Zou, Lianfeng; Caloz, Christophe

    2015-01-01

    We present a loss-gain equalized reconfigurable phaser for dynamic radio analog signal processing (R-ASP). Such a phaser provides real-time tunable group delay response with all-pass transmission. We propose a lumped loss-gain implementation, where tuning and equalization are mostly easily achieved. A theoretical study derives the transfer function and the fundamental characteristics of the device. The phaser is finally experimentally demonstrated, first using a single loss-gain pair and finally a three cascaded loss-gain pair structure with full reconfigurability , where up-chirp and down-chirp group delays are shown for illustration. It is expected that this phaser will find wide applications in radio analog signal processing (R-ASP) systems requiring dynamic adaptability.

  13. Concurrent neuromechanical and functional gains following upper-extremity power training post-stroke

    Directory of Open Access Journals (Sweden)

    Patten Carolynn

    2013-01-01

    s p’s p Conclusions Functional and neuromechanical gains were greater following HYBRID vs. FPT. Improved stretch reflex modulation and increased neuromuscular activation indicate potent neural adaptations. Importantly, no deleterious consequences, including exacerbation of spasticity or musculoskeletal complaints, were associated with HYBRID. These results contribute to an evolving body of contemporary evidence regarding the efficacy of high-intensity training in neurorehabilitation and the physiological mechanisms that mediate neural recovery.

  14. An adaptive protocol for distributed beamforming

    OpenAIRE

    Sigg, Stephan; Beigl, Michael

    2011-01-01

    We study distributed adaptive beamforming in networks of wireless nodes. In particular, we observe that for the synchronisation of carrier phases, distinct algorithmic configurations are optimal in various environmental settings and propose a protocol that utilises organic computing principles to find optimum parameters. Furthermore, we study the impact of different modulation schemes on the bit error rate of a signal sequence transmitted collaboratively by distributed devices via adaptive be...

  15. Reducing gain shifts in photomultiplier tubes

    Science.gov (United States)

    Cohn, Charles E.

    1976-01-01

    A means is provided for reducing gain shifts in multiplier tubes due to varying event count rates. It includes means for limiting the number of cascaded, active dynodes of the multiplier tube to a predetermined number with the last of predetermined number of dynodes being the output terminal of the tube. This output is applied to an amplifier to make up for the gain sacrificed by not totally utilizing all available active stages of the tube. Further reduction is obtained by illuminating the predetermined number of dynodes with a light source of such intensity that noise appearing at the output dynode associated with the illumination is negligible.

  16. Gains from Cartelisation in the Oil Market

    OpenAIRE

    Berg, Elin; Kverndokk, Snorre; Rosendahl, Knut Einar

    1996-01-01

    In this paper we ask whether OPEC still gains from cartelisation in the oil market despite low producer prices and a modest market share. We apply two intertemporal equilibrium models of the global oil market; one consisting of a cartel and a fringe, and one describing a hypothetical competitive market. Comparing the outcome of these models we conclude that there are positive cartelisation gains of about 18 per cent in the oil market. In comparison with what Pindyck (1978) found for the 1970s...

  17. Speech perception of noise with binary gains

    DEFF Research Database (Denmark)

    Wang, DeLiang; Kjems, Ulrik; Pedersen, Michael Syskind;

    2008-01-01

    For a given mixture of speech and noise, an ideal binary time-frequency mask is constructed by comparing speech energy and noise energy within local time-frequency units. It is observed that listeners achieve nearly perfect speech recognition from gated noise with binary gains prescribed by the i...... by the ideal binary mask. Only 16 filter channels and a frame rate of 100 Hz are sufficient for high intelligibility. The results show that, despite a dramatic reduction of speech information, a pattern of binary gains provides an adequate basis for speech perception....

  18. Effect of gain nonlinearity in semiconductor lasers

    DEFF Research Database (Denmark)

    Jensen, Niels H.; Christiansen, Peter Leth; Skovgaard, Ove

    1988-01-01

    Semiconductor lasers are modeled by single-mode rate equations with Langevin noise terms and the influence of nonlinear gain is investigated. For cw operation the probability distribution for the carrier number and the photon number in the laser cavity is obtained. The corresponding (2+1)-dimensi......Semiconductor lasers are modeled by single-mode rate equations with Langevin noise terms and the influence of nonlinear gain is investigated. For cw operation the probability distribution for the carrier number and the photon number in the laser cavity is obtained. The corresponding (2...

  19. GAiN: Distributed Array Computation with Python

    Energy Technology Data Exchange (ETDEWEB)

    Daily, Jeffrey A. [Washington State Univ., Pullman, WA (United States)

    2009-05-01

    Scientific computing makes use of very large, multidimensional numerical arrays - typically, gigabytes to terabytes in size - much larger than can fit on even the largest single compute node. Such arrays must be distributed across a "cluster" of nodes. Global Arrays is a cluster-based software system from Battelle Pacific Northwest National Laboratory that enables an efficient, portable, and parallel shared-memory programming interface to manipulate these arrays. Written in and for the C and FORTRAN programming languages, it takes advantage of high-performance cluster interconnections to allow any node in the cluster to access data on any other node very rapidly. The "numpy" module is the de facto standard for numerical calculation in the Python programming language, a language whose use is growing rapidly in the scientific and engineering communities. numpy provides a powerful N-dimensional array class as well as other scientific computing capabilities. However, like the majority of the core Python modules, numpy is inherently serial. Our system, GAiN (Global Arrays in NumPy), is a parallel extension to Python that accesses Global Arrays through numpy. This allows parallel processing and/or larger problem sizes to be harnessed almost transparently within new or existing numpy programs.

  20. The V1 Population Gains Normalization

    NARCIS (Netherlands)

    Ganmor, Elad; Okun, Michael; Lampl, Ilan

    2009-01-01

    In this issue of Neuron, Busse et al. describe the population response to superimposed visual stimuli while Sit et al. examine the spatiotemporal evolution of cortical activation in response to small visual stimuli. Surprisingly, these two studies of V1 report that a single gain control model accoun

  1. Design for logistics to gain competitive advantage

    DEFF Research Database (Denmark)

    Chaudhuri, Atanu; Biskoptsø, Rogvi

    2015-01-01

    . Considering logistical requirements in design of a product which is heavy and bulky and involves significant logistics costs enabled to firm to gain competitiveness. The exercise underscored the importance of understanding logistical requirements, freight costs and dimensional constraints early in the design...

  2. Challenges and Gains in Cyber Security [video

    OpenAIRE

    Antonio Scurlock; Center for Homeland Defense and Security Naval Postgraduate School

    2015-01-01

    Cybersecurity is now at the forefront of Homeland Security threats. Antonio Scurlock, (Senior Cybersecurity Strategist Enhance Shared Situational Awareness (ESSA) Portfolio Lead Office of Strategy, Policy, & Plans National Protection and Programs Directorate) talks about the challenges and gains made in cybersecurity and cybersecurity programs over the years.

  3. Gaining Insights into Children's Geometric Knowledge

    Science.gov (United States)

    Mack, Nancy K.

    2007-01-01

    This article describes how research on children's geometric thinking was used in conjunction with the picture book "The Greedy Triangle" to gain valuable insights into children's prior geometric knowledge of polygons. Exercises focused on the names, visual appearance, and properties of polygons, as well as real-world connections for each, are…

  4. Capital Gains Taxation and House Price Fluctuations

    DEFF Research Database (Denmark)

    Fuest, Clemens; Nielsen, Søren Bo

    2004-01-01

    Recent years have seen large swings in house prices in many countries. Motivated by housing price variations, proposals for taxing capital gains on housing have repeatedly been put forth. The idea seems to be that such taxes would curb the redistribution occurring between those owning houses and ...

  5. Weight Gain Through Self-Control Procedures

    Science.gov (United States)

    Gulanick, Nancy; And Others

    1975-01-01

    Underweight subjects were assigned to either a self-reinforcement condition, a self-punishment condition, or to a discussion/reflection control condition. The subjects received one treatment session per week over a five-week period. After treatment, the self-reinforcement groups gained significantly more pounds (kilograms) than either of the other…

  6. Pleasure Reading and Reading Rate Gains

    Science.gov (United States)

    Beglar, David; Hunt, Alan

    2014-01-01

    This study investigated the effects of (a) the amount of pleasure reading completed, (b) the type of texts read (i.e., simplified or unsimplified books), and (c) the level of simplified texts read by 14 Japanese university students who made the largest reading rate gains over one academic year. The findings indicated that the participants who made…

  7. The Biology of Intron Gain and Loss

    DEFF Research Database (Denmark)

    Jeffares, Daniel C; Mourier, Tobias; Penny, David

    2006-01-01

    Intron density in eukaryote genomes varies by more than three orders of magnitude, so there must have been extensive intron gain and/or intron loss during evolution. A favored and partial explanation for this range of intron densities has been that introns have accumulated stochastically in large...... on introns depending on the biology of the organism and the gene involved....

  8. Shanghai Performing Arts Fair Gaining Global Popularity

    Institute of Scientific and Technical Information of China (English)

    TianZui; ZuZhongren

    2003-01-01

    China Shanghai International Arts Festival Performing Arts Fair is gaining popularity. In two months after the dates of the fair were announced, all the 120 booths were booked out, and for the first time in the event's four-year history, participants had to scramble to get in. When the trade fair opened, about 40 organizations were shut out.

  9. Measured stimulated Raman gain in methane

    International Nuclear Information System (INIS)

    This report is about the stimulated Raman effect in methane due to the nu1 vibration. For various gas pressures between 150 torr and 30 atm, the Raman lineshape function was both experimentally measured and synthesized using a computer model. The stimulated Raman gain was measured by sending a pump laser beam provided by an argon-ion laser and a weak probe beam provided by a tunable dye laser through a cell of methane gas. The stimulated Raman effect caused some of the energy from the pump beam to be transferred to the probe beam. The intensity of the pump beam was low so the gain of the probe beam was on the order of parts per million. A two detector arrangement and a differential amplifier system that had a feedback loop to balance the detectors was constructed to measure the small gains. A detailed description of this detection system that was able to measure gains as small as 0.2 parts per million is provided

  10. How to gain gain a reference book on triodes in audio pre-amps

    CERN Document Server

    Vogel, Burkhard

    2013-01-01

    The 34 chapters of the 2nd edition of How to Gain Gain give a detailed insight into a collection (54) of the most common gain producing, constant current generating possibilities, and electronic noise creation of triodes for audio pre-amplifier purposes. These chapters also offer complete sets of formulae to calculate gain, frequency and phase responses, and signal-to-noise ratios of certain building blocks built-up with this type of vacuum valve (tube). In all cases detailed derivations of the gain formulae are also presented. All what is needed are the data sheet valve characteristic figures of the triode's mutual conductance, the gain factor and the internal plate (anode) resistance. To calculate frequency and phase responses of gain stages the different data sheet based input and output capacitances have to be taken into account too. To calculate transfer functions and signal-to-noise ratios for any kind of triode driven gain stage, including all its bias setting, frequency, phase, and electronic noise in...

  11. 34 CFR 462.43 - How is educational gain measured?

    Science.gov (United States)

    2010-07-01

    ... ADULT EDUCATION, DEPARTMENT OF EDUCATION MEASURING EDUCATIONAL GAIN IN THE NATIONAL REPORTING SYSTEM FOR... 34 Education 3 2010-07-01 2010-07-01 false How is educational gain measured? 462.43 Section 462.43... Educational Gain? § 462.43 How is educational gain measured? (a)(1) Educational gain is measured by...

  12. A novel control method for on-off gain and gain tilt of fiber Raman amplifiers

    Institute of Scientific and Technical Information of China (English)

    Xue Feng(冯雪); Wei Zhang(张巍); Xiaoming Liu(刘小明); Jiangde Peng(彭江得)

    2004-01-01

    Considering spectrum tilt due to signal-to-signal Raman scattering (SSRS) in backward distributed fiber Raman amplifiers (B-DFRA), an inverse tilted on-off gain profile is adopted to achieve flat net gain. A simple approximate linear relationship of pump power at each wavelength versus on-off gain level and tilt was derived numerically and experimentally so that a novel control method was established. Since there are only 3 pre-determinable constants required for individual pump wave, it is easy to be realized. As an example, maximum errors less than 0.2 and 0.4 dB respectively for average gain and gain tilt were achieved over C+L band in 100-km back-pumped standard single-mode fiber (SMF) experimentally.

  13. Transient gain and cross talk in erbium-doped fiber amplifiers.

    Science.gov (United States)

    Giles, C R; Desurvire, E; Simpson, J R

    1989-08-15

    Transient gain saturation and recovery with 110-340-microsec time constants were observed in erbium-doped fiber amplifiers. This slow response reduces the effects of saturation-induced cross talk and intermodulation distortion associated with multichannel signal amplification. In a two-channel amplification experiment, negligible saturation-induced cross talk was measured at signal modulation frequencies >5 kHz. Increased suppression of saturation-induced cross talk was achieved through feed-forward compensation to reduce low-frequency gain fluctuations. PMID:19752999

  14. Pulse front adaptive optics in multiphoton microscopy

    Science.gov (United States)

    Sun, B.; Salter, P. S.; Booth, M. J.

    2016-03-01

    The accurate focusing of ultrashort laser pulses is extremely important in multiphoton microscopy. Using adaptive optics to manipulate the incident ultrafast beam in either the spectral or spatial domain can introduce significant benefits when imaging. Here we introduce pulse front adaptive optics: manipulating an ultrashort pulse in both the spatial and temporal domains. A deformable mirror and a spatial light modulator are operated in concert to modify contours of constant intensity in space and time within an ultrashort pulse. Through adaptive control of the pulse front, we demonstrate an enhancement in the measured fluorescence from a two photon microscope.

  15. Pulse front control with adaptive optics

    Science.gov (United States)

    Sun, B.; Salter, P. S.; Booth, M. J.

    2016-03-01

    The focusing of ultrashort laser pulses is extremely important for processes including microscopy, laser fabrication and fundamental science. Adaptive optic elements, such as liquid crystal spatial light modulators or membrane deformable mirrors, are routinely used for the correction of aberrations in these systems, leading to improved resolution and efficiency. Here, we demonstrate that adaptive elements used with ultrashort pulses should not be considered simply in terms of wavefront modification, but that changes to the incident pulse front can also occur. We experimentally show how adaptive elements may be used to engineer pulse fronts with spatial resolution.

  16. Customized PEC modules. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, Martin B. (DTI, Taastrup (Denmark))

    2012-07-01

    The purpose of the project ''Customized PEC modules'' was to move from the production hand-made individual DSCs (dye-sensitized solar cells) in the laboratory to the production of DSC modules in a semi-automated process. At the same time allowing sufficient variation in the product's specification for real tailoring of the product to the application. The tailoring can be related to the module's electrical output and size, but also to the possibility of designing patterns for decoration or communication purposes by playing around with the shape, size and layout of the individual cells forming the module. This was to be accomplished mainly by screen printing of DSC components on glass substrates at Mekoprint. For reaching this goal the work was divided into a number of steps. The central part of the work done was in the initial conception activity and the following manufacturing activity. An activity regarding optimization included several tasks of optimization and adaptation of the existing laboratory process for manufacturing of the DSCs. Finally, work focused on international activities was done. All the steps needed for the production of customized DSC modules have been demonstrated in this project. In combination with the development of a high performing printable sealant and sealing method all the prerequisites for producing customized DSC modules have been demonstrated. (LN)

  17. A general approach for temperature modulated thermogravimetry: Extension to non-periodical and event-controlled modulation

    International Nuclear Information System (INIS)

    Highlights: • The temperature modulated TGA technique is expanded to non-periodic modulation functions. • The use of a stochastic modulation function is tested. • The concept of the new technique, the event controlled temperature modulated TGA is introduced. • The event control adapted the intensity of the modulation function and the characteristic modulation time. The result is an optimized modulation. - Abstract: Sinusoidal temperature modulated thermogravimetric analysis (TMTGA) has been proposed to get kinetic data on reactions that were investigated by TGA 45 years ago by Flynn and later by Blaine and Hahn. Because of general uncertainties of this technique, we developed a generalized approach for TMTGA using any modulation function, i.e., periodic as well as non-periodic. As a consequence of an error discussion of a TMDSC experiment, we present a new concept of the event controlled modulation function

  18. Short-term adaptation of the VOR: non-retinal-slip error signals and saccade substitution

    Science.gov (United States)

    Eggers, Sscott D Z.; De Pennington, Nick; Walker, Mark F.; Shelhamer, Mark; Zee, David S.

    2003-01-01

    We studied short-term (30 min) adaptation of the vestibulo-ocular reflex (VOR) in five normal humans using a "position error" stimulus without retinal image motion. Both before and after adaptation a velocity gain (peak slow-phase eye velocity/peak head velocity) and a position gain (total eye movement during chair rotation/amplitude of chair motion) were measured in darkness using search coils. The vestibular stimulus was a brief ( approximately 700 ms), 15 degrees chair rotation in darkness (peak velocity 43 degrees /s). To elicit adaptation, a straight-ahead fixation target disappeared during chair movement and when the chair stopped the target reappeared at a new location in front of the subject for gain-decrease (x0) adaptation, or 10 degrees opposite to chair motion for gain-increase (x1.67) adaptation. This position-error stimulus was effective at inducing VOR adaptation, though for gain-increase adaptation the primary strategy was to substitute augmenting saccades during rotation while for gain-decrease adaptation both corrective saccades and a decrease in slow-phase velocity occurred. Finally, the presence of the position-error signal alone, at the end of head rotation, without any attempt to fix upon it, was not sufficient to induce adaptation. Adaptation did occur, however, if the subject did make a saccade to the target after head rotation, or even if the subject paid attention to the new location of the target without actually looking at it.

  19. Adaptation in the fuzzy self-organising controller

    DEFF Research Database (Denmark)

    Jantzen, Jan; Poulsen, Niels Kjølstad

    2003-01-01

    This simulation study provides an analysis of the adaptation mechanism in the self-organising fuzzy controller, SOC. The approach is to apply a traditional adaptive control viewpoint. A simplified performance measure in the SOC controller is used in a loss function, and thus the MIT rule implies...... an update mechanism similar to the SOC update mechanism. Two simulations of proportionally controlled systems show the behaviour of the proportional gain as it adapts to a specified behaviour....

  20. Impacts of cross-phase modulation on modulation instability of Airy pulses

    Science.gov (United States)

    Cheng, Yingkai; Fu, Xiquan; Bai, Yanfeng

    2016-10-01

    The modulation instability (MI) of Airy pulses with the influence of cross-phase modulation is studied based on the coupled nonlinear Schrödinger equations in nonlinear media. The main lobe of Airy pulses can be manifested as breakup of MI under interaction with higher power pumped solitons, although the power of Airy pulses is small. By comparing the main lobe's gain spectrum of MI, the gain spectrum has gradually improved with the increase of power of pumped solitons. The gain spectrum of MI of the main lobe is inversely proportional to the truncation coefficient, and then it gradually approaches to that of Gauss pulses with the truncation coefficient increasing to 1. For the side lobes of Airy pulses, there are similar MI but smaller gain spectrum than the main lobe when the pumped solitons is overlapping with corresponding ones of Airy pulses.

  1. Unity connecting module in SSPF

    Science.gov (United States)

    1998-01-01

    In the Space Station Processing Facility, the Unity connecting module, part of the International Space Station, is shown with Pressurized Mating Adapters 1 (left) and 2 (right) attached. Unity is scheduled to undergo testing of the common berthing mechanism to which other space station elements will dock. Unity is the primary payload on mission STS-88, targeted to launch Dec. 3, 1998. Other testing includes the Pad Demonstration Test to verify the compatibility of the module with the Space Shuttle as well as the ability of the astronauts to send and receive commands to Unity from the flight deck of the orbiter. Unity is expected to be ready for installation into the payload canister on Oct. 25, and transported to Launch Pad 39-A on Oct. 27. The Unity will be mated to the Russian-built Zarya control module which should already be in orbit at that time.

  2. Adaptable beam profiles from a dual-cavity Nd:YAG laser.

    Science.gov (United States)

    Kim, D J; Mackenzie, J I; Kim, J W

    2016-04-15

    We report a technique to tailor a laser beam profile from a donut to quasi-top-hat intensity distribution, directly from the laser, simply achieved by simultaneous excitation and control of the relative contributions of the fundamental (TEM00) and first-order Laguerre-Gaussian (LG01) transverse modes. Exploiting a dual-cavity configuration with a single Nd:YAG gain element, adaptable continuous-wave laser beam profiles from the primary cavity could be obtained by varying the diffraction loss of an acousto-optic modulator in the secondary cavity. We investigate the resultant beam profiles as a function of pump power and the AOM diffraction loss, and discuss the prospects for tunable laser beams profiles.

  3. Controlling Scattering Instabilities and Adapting to Unknown and Changing Plasma Conditions Using STUD Pulses

    Science.gov (United States)

    Afeyan, Bedros; Hüller, Stefan

    2012-10-01

    We will show the results of changing STUD pulse configurations in order to maintain strict control of parametric instabilities in high energy density plasmas (HEDP). Nonlinear optical processes (NLOP) in HEDP respond to changing plasma conditions which are unknown and not easily knowable by standard experimental procedures. Adapting to changing and unknown plasma conditions is one feature of STUD pulses which is absent in other beam conditioning techniques. We demonstrate this by simulating long enough that plasma conditions change, instability gains are altered and new STUD pulse configurations become necessary. Two such configurations are spliced together or run independently and compared. All available methods of changing STUD pulse characteristics are explored, such as duty cycle (20% vs 50%) and modulation period (cutting hot spots in half and into quarters) as well as phase scrambling and number of spikes before the spatial distribution of hot spots is randomized (1, 2, 3 and infinity).

  4. An Energy Efficient Semi-static Power Control and Link Adaptation Scheme in UMTS HSDPA

    CERN Document Server

    Huang, Yi; Qiu, Ling

    2012-01-01

    High speed downlink packet access (HSDPA) has been successfully applied in commercial systems and improves user experience significantly. However, it incurs substantial energy consumption. In this paper, we address this issue by proposing a novel energy efficient semi-static power control and link adaptation scheme in HSDPA. Through estimating the EE under different modulation and coding schemes (MCSs) and corresponding transmit power, the proposed scheme can determine the most energy efficient MCS level and transmit power at the Node B. And then the Node B configure the optimal MCS level and transmit power. In order to decrease the signaling overhead caused by the configuration, a dual trigger mechanism is employed. After that, we extend the proposed scheme to the multiple input multiple output (MIMO) scenarios. Simulation results confirm the significant EE improvement of our proposed scheme. Finally, we give a discussion on the potential EE gain and challenge of the energy efficient mode switching between s...

  5. Gain Variation with Raman Amplifier Parameters and Its Restoration

    Institute of Scientific and Technical Information of China (English)

    Zhaohui Li; Chao Lu; Jian Chen

    2003-01-01

    We demonstrate that gain profile of a distributed Raman amplifier is sensitive to its parameter variation, such as loss/gain coefficients change or partial pump failure. Gain flatness can be restored by adjusting power of pump lasers.

  6. An automated approach for solution based mesh adaptation to enhance numerical accuracy for a given number of grid cells

    NARCIS (Netherlands)

    Lucas, P.; Van Zuijlen, A.H.; Bijl, H.

    2009-01-01

    Mesh adaptation is a fairly established tool to obtain numerically accurate solutions for flow problems. Computational efficiency is, however, not always guaranteed for the adaptation strategies found in literature. Typically excessive mesh growth diminishes the potential efficiency gain. This paper

  7. Rack assembly for mounting solar modules

    Science.gov (United States)

    Plaisted, Joshua Reed; West, Brian

    2010-12-28

    A rack assembly is provided for mounting solar modules over an underlying body. The rack assembly may include a plurality of rail structures that are arrangeable over the underlying body to form an overall perimeter for the rack assembly. One or more retention structures may be provided with the plurality of rail structures, where each retention structure is configured to support one or more solar modules at a given height above the underlying body. At least some of the plurality of rail structures are adapted to enable individual rail structures o be sealed over the underlying body so as to constrain air flow underneath the solar modules. Additionally, at least one of (i) one or more of the rail structures, or (ii) the one or more retention structures are adjustable so as to adapt the rack assembly to accommodate solar modules of varying forms or dimensions.

  8. Generalized modular multilevel converter and modulation

    DEFF Research Database (Denmark)

    Liu, Hui; Loh, Poh Chiang; Blaabjerg, Frede

    2014-01-01

    Modular multilevel converter (MMC) has gained popularity recently with its modulation, capacitor voltage balancing and circulating current issues widely discussed. Contributing to this effort, a study is presented here to show how the MMC topology can be derived from the viewpoint of two series c...

  9. Modulational instability in periodic quadratic nonlinear materials

    DEFF Research Database (Denmark)

    Corney, Joel Frederick; Bang, Ole

    2001-01-01

    We investigate the modulational instability of plane waves in quadratic nonlinear materials with linear and nonlinear quasi-phase-matching gratings. Exact Floquet calculations, confirmed by numerical simulations, show that the periodicity can drastically alter the gain spectrum but never complete...

  10. The gain from improved market efficiency

    DEFF Research Database (Denmark)

    Ejrnæs, Mette; Persson, Karl Gunnar

    2010-01-01

    demand as well as excess supply, which triggered off the tâtonnement process. Over time, adjustments to equilibrium, as measured by the half-life of a shock, became faster and violations of the law of one price become smaller. There were significant gains from improved market efficiency, which took place......This article looks at the gains from improved market efficiency in long-distance grain trade in the second half of the nineteenth century, when violations of the law of one price were reduced due to improved information transmission. Two markets, a major export centre, Chicago, and a major importer......, Liverpool, are analysed. We show that the law of one price equilibrium was an ‘attractor equilibrium'. The implication is that prices converged to that equilibrium in a tâtonnement process. Because of asymmetrically timed information between markets separated by long distances there were periods of excess...

  11. Gain stabilization for radioactivity well logging apparatus

    International Nuclear Information System (INIS)

    Gain stabilization is provided for well logging apparatus of the type having a scintillation crystal optically coupled to a photomultiplier in a sonde to detect radiation in the borehole and formation elements in response to neutron bombardment. The gain stabilization apparatus includes a light emitting diode driven by a pulser to furnish regular scintillations to the photomultiplier, resulting in a stabilization pulse which is furnished to a spectrum stabilizer at the surface. The light emitting diode is provided with means for mounting the LED between the scintillation crystal and the photomultiplier, and for providing optical coupling such that the scintillations from the LED are sensed by and pass through the same system as the operative scintillations from the detector crystal. The mounting means may be provided with a groove for locating temperature-compensating elements. (author)

  12. Directionality switchable gain stabilized linear repeater

    Science.gov (United States)

    Ota, Takayuki; Ohmachi, Tadashi; Aida, Kazuo

    2004-10-01

    We propose a new approach to realize a bidirectional linear repeater suitable for future optical internet networks and fault location in repeater chain with OTDR. The proposed approach is the linear repeater of simple configuration whose directionality is rearranged dynamically by electrical control signal. The repeater is composed of a magneto-optical switch, a circulator, a dynamically gain stabilized unidirectional EDFA, and control circuits. The repeater directionality is rearranged as fast as 0.1ms by an electrical control pulse. It is experimentally confirmed that OTDR with the directionality switchable repeater is feasible for repeater chain. The detailed design and performance of the repeater are also discussed, including the multi-pass interference (MPI) which may arise in the proposed repeater, the effect of the MPI on SNR degradation of the repeater chain and the feed-forward EDFA gain control circuit.

  13. The Gains from Improved Market Efficiency

    DEFF Research Database (Denmark)

    Persson, Karl Gunnar; Ejrnæs, Mette

    faster, violations of the law of one price become smaller and hence less persistent. There were also significant gains from improved market efficiency but that improvement took place after the information ‘regime’ shifted from pre-telegraphic communication to a regime with swift transmission...... of information in an era which developed a sophisticated commercial press and telegraphic communication. Improved market efficiency probably stimulated trade more than falling transport costs......This paper looks at the gains from improved market efficiency in long-distance grain trade in the second half of the 19th century when violations of the law of one price were reduced due to improved information transmission. Two markets, a major export centre, Chicago, and a major importer...

  14. Pole placement with constant gain output feedback

    Science.gov (United States)

    Sridhar, B.; Lindorff, D. P.

    1972-01-01

    Given a linear time invariant multivariable system with m inputs and p outputs, it was shown that p closed loop poles of the system can be preassigned arbitrarily using constant gain output feedback provided (A circumflex, B circumflex) is controllable. These data show that if (A circumflex, B circumflex, C circumflex) is controllable and observable, and Rank B circumflex = m, Rank C circumflex = p, then max (m,p) poles of the system can be assigned arbitarily using constant gain output feedback. Further, it is shown that in some cases more than max (m,p) poles can be arbitrarily assigned. A least square design technique is outlined to approximate the desired pole locations when it is not possible to place all the poles.

  15. Sabbatical leave: who gains and how much?

    Science.gov (United States)

    Davidson, Oranit B; Eden, Dov; Westman, Mina; Cohen-Charash, Yochi; Hammer, Leslie B; Kluger, Avraham N; Krausz, Moshe; Maslach, Christina; O'Driscoll, Michael; Perrewé, Pamela L; Quick, James Campbell; Rosenblatt, Zehava; Spector, Paul E

    2010-09-01

    A rigorous quasi-experiment tested the ameliorative effects of a sabbatical leave, a special case of respite from routine work. We hypothesized that (a) respite increases resource level and well-being and (b) individual differences and respite features moderate respite effects. A sample of 129 faculty members on sabbatical and 129 matched controls completed measures of resource gain, resource loss, and well-being before, during, and after the sabbatical. Among the sabbatees, resource loss declined and resource gain and well-being rose during the sabbatical. The comparison group showed no change. Moderation analysis revealed that those who reported higher respite self-efficacy and greater control, were more detached, had a more positive sabbatical experience, and spent their sabbatical outside their home country enjoyed more enhanced well-being than others.

  16. Noise Gain Features of Fiber Raman Amplifier

    Directory of Open Access Journals (Sweden)

    Georgii S. Felinskyi

    2016-01-01

    Full Text Available The formation dynamics of the optical noise in a silica single mode fiber (SMF as function of the pump power variation in the counter pumped fiber Raman amplifier (FRA is experimentally studied. The ratio between the power of amplified spontaneous emission and the power of incoherent optical noise is quantitatively determined by detailed analysis of experimental data in the pump powers range of 100–300 mW within the full band of Stokes frequencies, including FRA working wavelengths over the C + L transparency windows. It is found out the maximum of Raman gain coefficient for optical noise does not exceed ~60% of corresponding peak at the gain profile maximum of coherent signal. It is shown that the real FRA noise figure may be considerably less than 3 dB over a wide wavelength range (100 nm at a pump power of several hundreds of mW.

  17. Feedback Loop Gains and Feedback Behavior (1996)

    DEFF Research Database (Denmark)

    Kampmann, Christian Erik

    2012-01-01

    Linking feedback loops and system behavior is part of the foundation of system dynamics, yet the lack of formal tools has so far prevented a systematic application of the concept, except for very simple systems. Having such tools at their disposal would be a great help to analysts in understanding...... large, complicated simulation models. The paper applies tools from graph theory formally linking individual feedback loop strengths to the system eigenvalues. The significance of a link or a loop gain and an eigenvalue can be expressed in the eigenvalue elasticity, i.e., the relative change...... of an eigenvalue resulting from a relative change in the gain. The elasticities of individual links and loops may be found through simple matrix operations on the linearized system. Even though the number of feedback loops can grow rapidly with system size, reaching astronomical proportions even for modest systems...

  18. Contrast Gain Control Model Fits Masking Data

    Science.gov (United States)

    Watson, Andrew B.; Solomon, Joshua A.; Null, Cynthia H. (Technical Monitor)

    1994-01-01

    We studied the fit of a contrast gain control model to data of Foley (JOSA 1994), consisting of thresholds for a Gabor patch masked by gratings of various orientations, or by compounds of two orientations. Our general model includes models of Foley and Teo & Heeger (IEEE 1994). Our specific model used a bank of Gabor filters with octave bandwidths at 8 orientations. Excitatory and inhibitory nonlinearities were power functions with exponents of 2.4 and 2. Inhibitory pooling was broad in orientation, but narrow in spatial frequency and space. Minkowski pooling used an exponent of 4. All of the data for observer KMF were well fit by the model. We have developed a contrast gain control model that fits masking data. Unlike Foley's, our model accepts images as inputs. Unlike Teo & Heeger's, our model did not require multiple channels for different dynamic ranges.

  19. CAPITAL GAINS: BLUE MACHINES AND RED MACHINES

    OpenAIRE

    LUÍS AGUIAR-CONRARIA; KARL SHELL

    2005-01-01

    Capital gains play an essential role in the intertemporal allocation of resources, but they can also fuel self-fulfilling bubbles. The simple case of 2 "identical" capitals is analyzed in an overlapping generations model. The only trajectory in which expectations are realized at every date is the one in which blue machines and red machines have the same price. If ever their prices differ, then there is a "bubble" which must burst in finite time.

  20. Capital gains taxation under different tax regimes

    OpenAIRE

    Sureth, Caren; Langeleh, Dirk

    2005-01-01

    This paper investigates the influence of different systems of current income and capital gains taxation on investor's decision to either carry out an investment in corporate shares or to invest funds alternatively on the capital market. Three basic tax systems are analyzed, a classical corporate tax system with double taxation of profits on corporate and personal level, a shareholder relief system, that reduces double taxation completely. It can be shown that general analytical solutions for ...

  1. Assessing gains from parallel computation on supercomputers

    OpenAIRE

    Lilia Maliar

    2013-01-01

    We assess gains from parallel computation on Backlight supercomputer. We find that information transfers are expensive. To make parallel computation efficient, a task per core must be sufficiently large, ranging from few seconds to one minute depending on the number of cores employed. For small problems, the shared memory programming (OpenMP) leads to a higher efficiency of parallelization than the distributive memory programming (MPI).

  2. The Persistence of Gaining and Losing Streams

    Science.gov (United States)

    McNamara, J. P.; Frye, A.

    2012-12-01

    Streams are commonly classified as "gaining" or "losing", according to their relationships with groundwater. However, the gaining and losing nature of a stream can vary in space and time. Understanding the spatial and temporal persistence of gaining and losing reaches is essential for understanding controls on stream health. This is particularly important during low flow conditions. Hydrologic models are typically designed to simulate high flows, and are challenged by low flow. This problem will become more important as hydrologists are asked to forecast the increasing occurrence of low flows as a consequence of climate change. Low flow discharges have been a focus of research as they are occurring earlier in the summer and have longer durations throughout the fall. A concern is how low flow will affect water resources and its users in the region when demand is at its highest. As low flow discharges continue to persist, debate over these rights will continue as well. This study we used chloride as a chemical tracer to monitor gains and losses of stream discharge of small watershed in Southwestern, Idaho. Six conductivity probes were spaced evenly 200m apart along a control reach 1200m in total length. Tracers were performed at least once a month at this site throughout the winter and spring and even more often during the summer dry down to understand the temporal changes occurring. Spatial variations were observed by performing basin wide tracers over a stream length of ~9km during the spring and late summer. Results show that stream baseflow is dependent on the winter snowpack and spring rains in order to recharge the deep groundwater systems and to create a hydrologic connection between the stream and local hillslopes. As a result, when winter snowpack's and spring rains are mild, this connectivity is cut off much sooner producing low flow conditions much earlier in the summer.

  3. Stock Price Booms and Expected Capital Gains

    OpenAIRE

    Adam, Klaus; Beutel, Johannes; Marcet, Albert

    2014-01-01

    The booms and busts in U.S. stock prices over the post-war period can to a large extent be explained by fluctuations in investors' subjective capital gains expectations. Survey measures of these expectations display excessive optimism at market peaks and excessive pessimism at market troughs. Formally incorporating subjective price beliefs into an otherwise standard asset pricing model with utility maximizing investors, we show how subjective belief dynamics can temporarily delink stock price...

  4. Real Estate and Capital Gains Debate

    OpenAIRE

    Michael Hudson; Kris Feder

    1997-01-01

    This working paper seeks to elucidate the role of real estate in the capital gains issue, indicating the quantitative orders of magnitude involved. We offer two main observations. First, generous capital consumption allowances (CCAs) greatly magnify the proportion newly constructed buildings, of course, but also on land and old buildings being sold and resold. Our tax code allows for properties to be re- depreciated by their new owners after a sale or swap, permitting real estate investors to...

  5. A Brain Gain with a Brain Drain

    OpenAIRE

    Stark, Oded; Prskawetz, Alexia; Helmenstein, Christian

    1997-01-01

    Abstract: We study human capital depletion and formation in an economy open to out-migration, as opposed to an economy which is closed. Under the natural assumption of asymmetric information, the enlarged opportunities and the associated different structure of incentives can give rise to a brain gain in conjunction with a brain drain. Migration by high-skill members of its workforce notwithstanding, the home country can end up with a higher average level of human capital per worker.;

  6. Majorana Edge Modes with Gain and Loss

    CERN Document Server

    Yuce, C

    2016-01-01

    We consider a non-Hermitian generalization of the Kitaev model and study the existence of stable Majorana zero energy modes. We show that they exist in the limit of zero chemical potential even if balanced gain and loss are randomly distributed along the lattice. We show that Majorana zero modes also appear if the chemical potential is different from zero provided that not the full Hamiltonian but the non-Hermitian part of the Hamiltonian is PT symmetric.

  7. Majorana edge modes with gain and loss

    Science.gov (United States)

    Yuce, C.

    2016-06-01

    We consider a non-Hermitian generalization of the Kitaev model and study the existence of stable Majorana zero energy modes. We show that they exist in the limit of zero chemical potential even if balanced gain and loss are randomly distributed along the lattice. We show that Majorana zero modes also appear if the chemical potential is different from zero provided that not the full Hamiltonian but the non-Hermitian part of the Hamiltonian is PT symmetric.

  8. Adaptive Liquid Crystal Windows

    Energy Technology Data Exchange (ETDEWEB)

    Taheri, Bahman; Bodnar, Volodymyr

    2011-12-31

    Energy consumption by private and commercial sectors in the U.S. has steadily grown over the last decade. The uncertainty in future availability of imported oil, on which the energy consumption relies strongly, resulted in a dramatic increase in the cost of energy. About 20% of this consumption are used to heat and cool houses and commercial buildings. To reduce dependence on the foreign oil and cut down emission of greenhouse gases, it is necessary to eliminate losses and reduce total energy consumption by buildings. To achieve this goal it is necessary to redefine the role of the conventional windows. At a minimum, windows should stop being a source for energy loss. Ideally, windows should become a source of energy, providing net gain to reduce energy used to heat and cool homes. It is possible to have a net energy gain from a window if its light transmission can be dynamically altered, ideally electronically without the need of operator assistance, providing optimal control of the solar gain that varies with season and climate in the U.S. In addition, the window must not require power from the building for operation. Resolution of this problem is a societal challenge and of national interest and will have a broad global impact. For this purpose, the year-round, allclimate window solution to provide an electronically variable solar heat gain coefficient (SHGC) with a wide dynamic range is needed. AlphaMicron, Inc. (AMI) developed and manufactured 1ft × 1ft prototype panels for the world’s first auto-adjusting Adaptive Liquid Crystal Windows (ALCWs) that can operate from sunlight without the need for external power source and demonstrate an electronically adjustable SHGC. This novel windows are based on AlphaMicron’s patented e-Tint® technology, a guesthost liquid crystal system implemented on flexible, optically clear plastic films. This technology is suitable both for OEM and aftermarket (retro-fitting) lamination to new and existing windows. Low level of

  9. Sensor management based on fisher information gain

    Institute of Scientific and Technical Information of China (English)

    Tian Kangsheng; Zhu Guangxi

    2006-01-01

    Multi-sensor system is becoming increasingly important in a variety of military and civilian applications. In general, single sensor system can only provide partial information about environment while multi-sensor system provides a synergistic effect, which improves the quality and availability of information. Data fusion techniques can effectively combine this environmental information from similar and/or dissimilar sensors. Sensor management, aiming at improving data fusion performance by controlling sensor behavior, plays an important role in a data fusion process. This paper presents a method using fisher information gain based sensor effectiveness metric for sensor assignment in multi-sensor and multi-target tracking applications. The fisher information gain is computed for every sensor-target pairing on each scan. The advantage for this metric over other ones is that the fisher information gain for the target obtained by multi-sensors is equal to the sum of ones obtained by the individual sensor, so standard transportation problem formulation can be used to solve this problem without importing the concept of pseudo sensor. The simulation results show the effectiveness of the method.

  10. Multiuser Diversity Gain in Cognitive Networks

    CERN Document Server

    Tajer, Ali

    2010-01-01

    Dynamic allocation of resources to the \\emph{best} link in large multiuser networks offers considerable improvement in spectral efficiency. This gain, often referred to as \\emph{multiuser diversity gain}, can be cast as double-logarithmic growth of the network throughput with the number of users. In this paper we consider large cognitive networks granted concurrent spectrum access with license-holding users. The primary network affords to share its under-utilized spectrum bands with the secondary users. We assess the optimal multiuser diversity gain in the cognitive networks by quantifying how the sum-rate throughput of the network scales with the number of secondary users. For this purpose we look at the optimal pairing of spectrum bands and secondary users, which is supervised by a central entity fully aware of the instantaneous channel conditions, and show that the throughput of the cognitive network scales double-logarithmically with the number of secondary users ($N$) and linearly with the number of avai...

  11. Signal Constellations for Multilevel Coded Modulation with Sparse Graph Codes

    NARCIS (Netherlands)

    Cronie, Harm S.

    2005-01-01

    A method to combine error-correction coding and spectral efficient modulation for transmission over channels with Gaussian noise is presented. The method of modulation leads to a signal constellation in which the constellation symbols have a nonuniform distribution. This gives a so-called shape gain

  12. Adaptive dual-layer super-twisting control and observation

    Science.gov (United States)

    Edwards, Christopher; Shtessel, Yuri

    2016-09-01

    In this paper, a super-twisting-like structure with adaptive gains is proposed. The structure is parameterised by two scalar gains, both of which adapt, and by an additional time-varying term. The magnitudes of the adaptive terms are allowed to both increase and decrease as appropriate so that they are as small as possible, in the sense that they do not unnecessarily over-bound the uncertainty, and yet are large enough to sustain a sliding motion. In the paper, a new time varying gain is incorporated into the traditional super-twisting architecture. The proposed adaption law has a dual-layer structure which is formally analyzed using Lyapunov techniques. The additional term has the effect of simplifying the stability analysis whilst guaranteeing the second-order sliding mode properties of the traditional super-twisting scheme.

  13. Adaptive Control Using Residual Mode Filters Applied to Wind Turbines

    Science.gov (United States)

    Frost, Susan A.; Balas, Mark J.

    2011-01-01

    Many dynamic systems containing a large number of modes can benefit from adaptive control techniques, which are well suited to applications that have unknown parameters and poorly known operating conditions. In this paper, we focus on a model reference direct adaptive control approach that has been extended to handle adaptive rejection of persistent disturbances. We extend this adaptive control theory to accommodate problematic modal subsystems of a plant that inhibit the adaptive controller by causing the open-loop plant to be non-minimum phase. We will augment the adaptive controller using a Residual Mode Filter (RMF) to compensate for problematic modal subsystems, thereby allowing the system to satisfy the requirements for the adaptive controller to have guaranteed convergence and bounded gains. We apply these theoretical results to design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed wind turbine that has minimum phase zeros.

  14. Photovoltaic module mounting system

    Science.gov (United States)

    Miros, Robert H. J.; Mittan, Margaret Birmingham; Seery, Martin N.; Holland, Rodney H.

    2012-04-17

    A solar array mounting system having unique installation, load distribution, and grounding features, and which is adaptable for mounting solar panels having no external frame. The solar array mounting system includes flexible, pedestal-style feet and structural links connected in a grid formation on the mounting surface. The photovoltaic modules are secured in place via the use of attachment clamps that grip the edge of the typically glass substrate. The panel mounting clamps are then held in place by tilt brackets and/or mid-link brackets that provide fixation for the clamps and align the solar panels at a tilt to the horizontal mounting surface. The tilt brackets are held in place atop the flexible feet and connected link members thus creating a complete mounting structure.

  15. Adaptively robust filtering with classified adaptive factors

    Institute of Scientific and Technical Information of China (English)

    CUI Xianqiang; YANG Yuanxi

    2006-01-01

    The key problems in applying the adaptively robust filtering to navigation are to establish an equivalent weight matrix for the measurements and a suitable adaptive factor for balancing the contributions of the measurements and the predicted state information to the state parameter estimates. In this paper, an adaptively robust filtering with classified adaptive factors was proposed, based on the principles of the adaptively robust filtering and bi-factor robust estimation for correlated observations. According to the constant velocity model of Kalman filtering, the state parameter vector was divided into two groups, namely position and velocity. The estimator of the adaptively robust filtering with classified adaptive factors was derived, and the calculation expressions of the classified adaptive factors were presented. Test results show that the adaptively robust filtering with classified adaptive factors is not only robust in controlling the measurement outliers and the kinematic state disturbing but also reasonable in balancing the contributions of the predicted position and velocity, respectively, and its filtering accuracy is superior to the adaptively robust filter with single adaptive factor based on the discrepancy of the predicted position or the predicted velocity.

  16. Dependence module of the MINI plus adapted for sugar dependence: psychometric properties Módulo de dependência do MINI plus adaptado para dependência de açúcar: propriedades psicométricas

    Directory of Open Access Journals (Sweden)

    Marco Aurélio Camargo da Rosa

    2013-01-01

    Full Text Available This study aimed to analyze the factorial structure and the scale of measurement of the items for dependence of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV adapted for sugar consumption in order to verify if the structural characteristics can be applied to sugar dependence. The questionnaire was applied to a sample of 500 subjects in Brazil (67% female; mean age: 38 y.o.; 43% from weight control clinics; 63% with normal BMI. An exploratory factor analysis was performed to determine the factorial structure and unidimensionality; and, a Rasch model analysis, to verify unidimensionality and items distribution. The model with best fit is unidimensional. All items had good fit to the Rasch model with a reliability of .99, infit between .86 and 1.14 and outfit from .71 to 1.20. The items of MINI Plus adapted for sugar dependence presented good psychometric properties, suggesting that the dependence criteria of DSM-IV support the verification of the construct for sugar addiction.Analisar a estrutura fatorial e a escala de medida dos critérios de dependência do DSM-IV adaptado para açúcar a fim de verificar se as características estruturais são aplicaveis para dependência de açúcar. O questionário foi aplicado numa amostra de 500 pessoas (67% mulheres; média idade: 38 anos; 43% de clínicas obesidade; 63% IMC normal. A análise fatorial exploratória determinou a estrutura fatorial e unidimensionalidade; a análise de Rasch, a unidimensionalidade e distribuição dos itens. O modelo com melhor ajuste era unidimensional. Todos os itens apresentaram ajustes adequados na análise de Rasch com confiabilidade de 0,99, infit entre 0,86 a 1,14 e outfit entre 0,71 e 1,20. Os itens de dependência do MINI Plus adaptados para açúcar apresentaram boas propriedades psicométricas, sugerindo que os critérios do DSM-IV contribuem na verificação do constructo dependência de açúcar.

  17. How to gain gain a reference book on triodes in audio pre-amps

    CERN Document Server

    Vogel, Burkhard

    2008-01-01

    This book gives a detailed insight into the most common gain producing and constant current generating possibilities (28) of triodes for audio pre-amplifier purposes. It shows how to calculate first and spend money for expensive components later.

  18. Gain control through divisive inhibition prevents abrupt transition to chaos in a neural mass model

    OpenAIRE

    Papasavvas, Christoforos A.; Wang, Yujiang; Trevelyan, Andrew J; Kaiser, Marcus

    2015-01-01

    Experimental results suggest that there are two distinct mechanisms of inhibition in cortical neuronal networks: subtractive and divisive inhibition. They modulate the input-output function of their target neurons either by increasing the input that is needed to reach maximum output or by reducing the gain and the value of maximum output itself, respectively. However, the role of these mechanisms on the dynamics of the network is poorly understood. We introduce a novel population model and nu...

  19. The influence of gain compression factor on dynamical properties of single level InAs/GaAs quantum dot lasers

    CERN Document Server

    Qorbani, Mostafa; Hajizadeh, Omid; Borji, Mahdi Ahmadi

    2016-01-01

    In this paper, by representing a single level rate equation model for InAs/GaAs quantum dot lasers and computations by fourth order Runge-Kutta method some characteristics of the output laser are considered. The change of photon number in time and current and also the output power versus current with different gain compression factors are investigated for lasing from ground state (GS). Afterwards, the response function of small signal modulation for ground state in constant current but different gain compressions is surveyed. At last, we find an optimum value for gain compression factor in lasing from GS.

  20. 40G and 100G modules enable next generation networks

    Science.gov (United States)

    Hong, Jin; Schmidt, Ted; Traverso, Matt; Yoshikazu, Era

    2009-11-01

    With the wide scale deployment of 40Gbps in carrier networks underway and 100Gbps products on the horizon, 40Gbps and 100Gbps modules based on Multi Source Agreements (MSA) are gaining considerable interest and market acceptance. This paper discusses developments in 40Gbps and 100Gbps line side DWDM MSA modules and CFP based client side MSA modules as suppliers strive to address various system and network applications.