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Sample records for adaptive interference suppression

  1. Eigenanalysis-based adaptive interference suppression for source localization

    NASA Astrophysics Data System (ADS)

    Ren, Suiling; Ge, Fengxiang; Guo, Xin; Guo, Lianghao

    2012-11-01

    Passive sonar detection in shallow water environments is very difficult due to strong interference. In this paper, an eigenanalysis-based adaptive interference suppression method (EAAIS) is presented for source localization. First, using beamforming for each eigenvector of the cross-spectral density matrix (CSDM) and a priori knowledge of the target's bearing interval, the proposed method constructs an appropriate rule to adaptively and robustly identify which eigenvector does not contain dominant contributions from the target of interest (TOI). Then, the identified eigenvectors are subtracted from the CSDM for interference suppression and source location. Numerical simulation results show that the proposed method could effectively detect the TOI even in the presence of strong interference. In comparison with other adaptive interference suppression methods, the proposed method has better interference rejection capability and wider range of applications without a priori knowledge of the interference's position.

  2. First-Order Adaptive Azimuthal Null-Steering for the Suppression of Two Directional Interferers

    NASA Astrophysics Data System (ADS)

    Derkx, René M. M.

    2010-12-01

    An azimuth steerable first-order superdirectional microphone response can be constructed by a linear combination of three eigenbeams: a monopole and two orthogonal dipoles. Although the response of a (rotation symmetric) first-order response can only exhibit a single null, we will look at a slice through this beampattern lying in the azimuthal plane. In this way, we can define maximally two nulls in the azimuthal plane which are symmetric with respect to the main-lobe axis. By placing these two nulls on maximally two directional sources to be rejected and compensating for the drop in level for the desired direction, we can effectively reject these directional sources without attenuating the desired source. We present an adaptive null-steering scheme for adjusting the beampattern so as to obtain this suppression of the two directional interferers automatically. Closed-form expressions for this optimal null-steering are derived, enabling the computation of the azimuthal angles of the interferers. It is shown that the proposed technique has a good directivity index when the angular difference between the desired source and each directional interferer is at least 90 degrees.

  3. Interference suppression of SRS

    SciTech Connect

    Kochanov, V P

    2011-01-24

    The theory of three-wave SRS is developed, which takes into account nonlinear dispersion of a medium for arbitrary phases of the pump waves at the input to the medium. The effect of interference suppression of SRS is predicted for values of the total phase of the three-wave pump (2n+1){pi} (n=0, {+-}1, {+-}2...), the effect being caused by the destructive interference of polarisations of the nonresonant dipole-allowed transitions. The relation between the contributions of the linear and nonlinear dispersions to the SRS is found. It is shown that at a sufficiently large wave detuning, the anti-Stokes wave amplitude experiences spatial oscillations. (nonlinear-optics phenomena)

  4. Limits of adaptation, residual interferences

    NASA Technical Reports Server (NTRS)

    Mokry, Miroslav (Editor); Erickson, J. C., Jr.; Goodyer, Michael J.; Mignosi, Andre; Russo, Giuseppe P.; Smith, J.; Wedemeyer, Erich H.; Newman, Perry A.

    1990-01-01

    Methods of determining linear residual wall interference appear to be well established theoretically; however they need to be validated, for example by comparative studies of test data on the same model in different adaptive-wall wind tunnels as well as in passive, ventilated-wall tunnels. The GARTEur CAST 7 and the CAST 10/DOA 2 investigations are excellent examples of such comparative studies. Results to date in both one-variable and two-variable methods for nonlinear wall interference indicate that a great deal more research and validation are required. The status in 2D flow is advanced over that in 3D flow as is the case generally with adaptive-wall development. Nevertheless, it is now well established that for transonic testing with extensive supercritical flow present, significant wall interference is likely to exist in conventional ventilated test sections. Consequently, residual correction procedures require further development hand-in-hand with further adaptive-wall development.

  5. Adaptive interference techniques for mobile antennas

    NASA Technical Reports Server (NTRS)

    Griffiths, Lloyd J.; Satorius, E.

    1988-01-01

    The results of a study performed to investigate effective, low cost adaptive signal processing techniques for suppressing mutual satellite interference that can arise in a mobile satellite (MSAT) communication system are discussed. The study focused on the use of adaptive sidelobe cancelling as a method to overcome undesired interference caused by a multiplicity of satellite transmissions within the field of view of the ground station. Results are presented which show that the conventional sidelobe canceller produces undesired reduction of the useful signal. This effect is due to the presence of the useful component in the reference antenna element. An alternative structure, the generalized sidelobe canceller (GSC), has been proposed to overcome this difficulty. A preliminary investigation of possible implementations of the GSC was conducted. It was found that at most 8 bits would be required to implement the GSC processor under conditions in which the desired signal-to-interference ratio is 25 dB.

  6. Near-least-squares radio frequency interference suppression

    NASA Astrophysics Data System (ADS)

    Miller, Timothy R.; McCorkle, John W.; Potter, Lee C.

    1995-06-01

    We present an algorithm for the removal of narrow-band interference from wideband signals. We apply the algorithm to suppress radio frequency interference encountered by ultra- wideband synthetic aperture radar systems used for foliage- and ground-penetrating imaging. For this application, we seek maximal reduction of interference energy, minimal loss and distortion of wideband target responses, and real-time implementation. To balance these competing objectives, we exploit prior information concerning the interference environment in designing an estimate-and-subtract-estimation algorithm. The use of prior knowledge allows fast, near-least-squares estimation of the interference and permits iterative target signature excision in the interference estimation procedure to decrease estimation bias. The results is greater interference suppression, less target signature loss and distortion, and faster computation than is provided by existing techniques.

  7. Suppression: sound and light interference with targeting

    NASA Astrophysics Data System (ADS)

    VanMeenen, Kirsten M.; Short, Kenneth R.; DeMarco, Robert M.; Chua, Florence B.; Janal, Malvin N.; Servatius, Richard J.

    2006-05-01

    Civilian law enforcement and military operations on urban terrain (MOUT) regularly enter into unknown situations where some unidentified subset of the populace may possess armaments that may be used against them. Ultimately, the most relevant test of the effectiveness of non-lethal energies in these situations is their ability to interfere with the targeting of those weapons on the friendly forces. It is also the test that offers the most immediate and tangible reward in the prevention of personnel injuries. Perceptual interference (e.g., light-induced flash blindness) or distractions from loud noises may contribute to targeting interference. How much do various energies or perceptual interventions actually interfere with targeting? We have devised a program of experimentation that allows for the pure and precise measurement of interference with the targeting process by any of a broad range of energies and stimuli. Our primary focus has been on sound and light interference with targeting, and experiments toward that purpose are described here. As expected, targeting accuracy decreased and targeting latency increased as the distance from fixation point to the target increased. The light flash interfered more with shots at more distant targets. Furthermore, as the angle between the fixation point and the flash increased, targeting latency increased but targeting accuracy was unaffected. Thus, light interference is greatest when the flash is not at the point of fixation. These studies suggest that foveal flashes are less disruptive than peripheral flashes, and that disruption increases as targeting task demands increase.

  8. 47 CFR 80.217 - Suppression of interference aboard ships.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Suppression of interference aboard ships. 80.217 Section 80.217 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL... interference aboard ships. (a) A voluntarily equipped ship station receiver must not cause harmful...

  9. 47 CFR 80.217 - Suppression of interference aboard ships.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Suppression of interference aboard ships. 80.217 Section 80.217 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL... interference aboard ships. (a) A voluntarily equipped ship station receiver must not cause harmful...

  10. 47 CFR 80.217 - Suppression of interference aboard ships.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Suppression of interference aboard ships. 80.217 Section 80.217 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL... interference aboard ships. (a) A voluntarily equipped ship station receiver must not cause harmful...

  11. 47 CFR 80.217 - Suppression of interference aboard ships.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Suppression of interference aboard ships. 80.217 Section 80.217 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL... interference aboard ships. (a) A voluntarily equipped ship station receiver must not cause harmful...

  12. 47 CFR 80.217 - Suppression of interference aboard ships.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Suppression of interference aboard ships. 80.217 Section 80.217 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL... interference aboard ships. (a) A voluntarily equipped ship station receiver must not cause harmful...

  13. Residual interference and wind tunnel wall adaption

    NASA Technical Reports Server (NTRS)

    Mokry, Miroslav

    1989-01-01

    Measured flow variables near the test section boundaries, used to guide adjustments of the walls in adaptive wind tunnels, can also be used to quantify the residual interference. Because of a finite number of wall control devices (jacks, plenum compartments), the finite test section length, and the approximation character of adaptation algorithms, the unconfined flow conditions are not expected to be precisely attained even in the fully adapted stage. The procedures for the evaluation of residual wall interference are essentially the same as those used for assessing the correction in conventional, non-adaptive wind tunnels. Depending upon the number of flow variables utilized, one can speak of one- or two-variable methods; in two dimensions also of Schwarz- or Cauchy-type methods. The one-variable methods use the measured static pressure and normal velocity at the test section boundary, but do not require any model representation. This is clearly of an advantage for adaptive wall test section, which are often relatively small with respect to the test model, and for the variety of complex flows commonly encountered in wind tunnel testing. For test sections with flexible walls the normal component of velocity is given by the shape of the wall, adjusted for the displacement effect of its boundary layer. For ventilated test section walls it has to be measured by the Calspan pipes, laser Doppler velocimetry, or other appropriate techniques. The interface discontinuity method, also described, is a genuine residual interference assessment technique. It is specific to adaptive wall wind tunnels, where the computation results for the fictitious flow in the exterior of the test section are provided.

  14. On interference suppression using complementary filters in DS-SSS

    NASA Astrophysics Data System (ADS)

    Lee, Bong Woon; Essman, Joseph E.

    An alternate interference suppression method used in conjunction with direct-sequence spread-spectrum systems (DS-SSS) is proposed. It consists of a complementary filter and reference loop using a scalar filter in the Walsh-Hadamard domain. Analytical expressions for chip-error probability (Pe) in the reference loop are given, and the performance of the complementary filter is compared with that of the other suppression filters via a simulation. The results show that the complementary filter is superior to the other filters when Pe is less than 0.25.

  15. Matrix filter design for passive sonar interference suppression

    NASA Astrophysics Data System (ADS)

    Vaccaro, Richard J.; Chhetri, Amit; Harrison, Brian F.

    2004-06-01

    The performance of passive acoustic signal-processing techniques can become severely degraded when the acoustic source of interest is obscured by strong interference. The application of matrix filters to suppress interference while passing a signal of interest with minimal distortion is presented. An algorithm for single-frequency matrix filter design is developed by converting a constrained convex optimization problem into a sequence of unconstrained problems. The approach is extended to broadband data by incoherently combining the responses of matrix filters designed at frequencies across a band of interest. The responses of single-frequency and multifrequency matrix filters are shown. Examples are given which demonstrate the effectiveness of matrix filtering applied to matched-field localization of a weak source in the presence of a strong interferer and noise. These examples show the matrix filter effectively suppressing the interference, thereby enabling the localization of the weak source. Standard matched-field processing, without matrix filtering, is not effective in localizing the weak source.

  16. Suppression laws for multiparticle interference in Sylvester interferometers

    NASA Astrophysics Data System (ADS)

    Crespi, Andrea

    2015-01-01

    Quantum interference of correlated particles is a fundamental quantum phenomenon which carries signatures of the statistics properties of the particles, such as bunching or antibunching. In the presence of particular symmetries, interference effects take place with high visibility, one of the simplest cases being the suppression of coincident detection in the Hong-Ou-Mandel effect. Tichy et al., [Phys. Rev. Lett. 104, 220405 (2010), 10.1103/PhysRevLett.104.220405] recently demonstrated a simple sufficient criterion for the suppression of output events in the more general case of Fourier multiport beam splitters. Here we study the case in which 2q particles (either bosonic or fermionic) are injected simultaneously in different ports of a Sylvester interferometer with 2p≥2q modes. In particular, we prove a necessary and sufficient criterion for a significant fraction of output states to be suppressed, for specific input configurations. This may find application in assessing the indistinguishability of multiple single-photon sources and in the validation of boson sampling machines.

  17. Elastic suppression in Brillouin imaging by destructive interference

    NASA Astrophysics Data System (ADS)

    Antonacci, Giuseppe; Lepert, Guillaume; Paterson, Carl; Török, Peter

    2015-08-01

    Brillouin microscopy is an emerging technique to yield high spatial resolution mechanical images in a non-contact manner. The main challenge in Brillouin spectroscopy is given by the detection and the localisation of the Brillouin peaks, in particular, when a high amount of elastic light is collected. We demonstrate a purely interferometric method to suppress the parasitic light which overwhelms the Brillouin spectrum using destructive interference in a Michelson interferometer. A suppression ratio of 35 dB is readily achieved. Both double and single stage virtually imaged phased array spectrometers are tested showing that the Brillouin peaks can still be measured when the intensity of the elastic light is higher by 53 dB, hence, enabling 3D mechanical imaging of thin biological systems such as cells.

  18. Suppression of biodynamic interference in head-tracked teleoperation

    NASA Technical Reports Server (NTRS)

    Lifshitz, S.; Merhav, S. J.; Grunwald, A. J.; Tucker, G. E.; Tischler, M. B.

    1991-01-01

    The utility of helmet-tracked sights to provide pointing commands for teleoperation of cameras, lasers, or antennas in aircraft is degraded by the presence of uncommanded, involuntary heat motion, referred to as biodynamic interference. This interference limits the achievable precision required in pointing tasks. The noise contributions due to biodynamic interference consists of an additive component which is correlated with aircraft vibration and an uncorrelated, nonadditive component, referred to as remnant. An experimental simulation study is described which investigated the improvements achievable in pointing and tracking precision using dynamic display shifting in the helmet-mounted display. The experiment was conducted in a six degree of freedom motion base simulator with an emulated helmet-mounted display. Highly experienced pilot subjects performed precision head-pointing tasks while manually flying a visual flight-path tracking task. Four schemes using adaptive and low-pass filtering of the head motion were evaluated to determine their effects on task performance and pilot workload in the presence of whole-body vibration characteristic of helicopter flight. The results indicate that, for tracking tasks involving continuously moving targets, improvements of up to 70 percent can be achieved in percent on-target dwelling time and of up to 35 percent in rms tracking error, with the adaptive plus low-pass filter configuration. The results with the same filter configuration for the task of capturing randomly-positioned, stationary targets show an increase of up to 340 percent in the number of targets captured and an improvement of up to 24 percent in the average capture time. The adaptive plus low-pass filter combination was considered to exhibit the best overall display dynamics by each of the subjects.

  19. Adaptive Modal Identification for Flutter Suppression Control

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan T.; Drew, Michael; Swei, Sean S.

    2016-01-01

    In this paper, we will develop an adaptive modal identification method for identifying the frequencies and damping of a flutter mode based on model-reference adaptive control (MRAC) and least-squares methods. The least-squares parameter estimation will achieve parameter convergence in the presence of persistent excitation whereas the MRAC parameter estimation does not guarantee parameter convergence. Two adaptive flutter suppression control approaches are developed: one based on MRAC and the other based on the least-squares method. The MRAC flutter suppression control is designed as an integral part of the parameter estimation where the feedback signal is used to estimate the modal information. On the other hand, the separation principle of control and estimation is applied to the least-squares method. The least-squares modal identification is used to perform parameter estimation.

  20. Eye gaze adaptation under interocular suppression.

    PubMed

    Stein, Timo; Peelen, Marius V; Sterzer, Philipp

    2012-01-01

    The perception of eye gaze is central to social interaction in that it provides information about another person's goals, intentions, and focus of attention. Direction of gaze has been found to reflexively shift the observer's attention in the corresponding direction, and prolonged exposure to averted eye gaze adapts the visual system, biasing perception of subsequent gaze in the direction opposite to the adapting face. Here, we tested the role of conscious awareness in coding eye gaze directions. To this end, we measured aftereffects induced by adapting faces with different eye gaze directions that were presented during continuous flash suppression, a potent interocular suppression technique. In some trials the adapting face was rendered fully invisible, whereas in others it became partially visible. In Experiment 1, the adapting and test faces were presented in identical sizes and to the same eye. Even fully invisible faces were capable of inducing significant eye gaze aftereffects, although these were smaller than aftereffects from partially visible faces. When the adapting and test faces were shown to different eyes in Experiment 2, significant eye gaze aftereffects were still observed for the fully invisible faces, thus showing interocular transfer. Experiment 3 disrupted the spatial correspondence between adapting and test faces by introducing a size change. Under these conditions, aftereffects were restricted to partially visible adapting faces. These results were replicated in Experiment 4 using a blocked adaptation design. Together, these findings indicate that size-dependent low-level components of eye gaze can be represented without awareness, whereas object-centered higher-level representations of eye gaze directions depend on visual awareness. PMID:22753441

  1. Adaptive flutter suppression, analysis and test

    NASA Technical Reports Server (NTRS)

    Johnson, E. H.; Hwang, C.; Joshi, D. S.; Harvey, C. A.; Huttsell, L. T.; Farmer, M. G.

    1983-01-01

    Methods of adaptive control have been applied to suppress a potentially violent flutter condition of a half-span model of a lightweight figher aircraft. This marked the confluence of several technologies with active flutter suppression, digital control and adaptive control theory the primary contributors. The control algorithm was required to adapt both to slowly varying changes, corresponding to changes in the flight condition or fuel loading and to rapid changes, corresponding to a store release or the transition from a stable to an unstable flight condition. The development of the adaptive control methods was followed by a simulation and checkout of the complete system and a wind tunnel demonstration. As part of the test, a store was released from the model wing tip, transforming the model abruptly from a stable configuration to a violent flutter condition. The adaptive algorithm recognized the unstable nature of the resulting configuration and implemented a stabilizing control law in a fraction of a second. The algorithm was also shown to provide system stability over a range of wind tunnel Mach numbers and dynamic pressures.

  2. Adaptive Suppression of Noise in Voice Communications

    NASA Technical Reports Server (NTRS)

    Kozel, David; DeVault, James A.; Birr, Richard B.

    2003-01-01

    A subsystem for the adaptive suppression of noise in a voice communication system effects a high level of reduction of noise that enters the system through microphones. The subsystem includes a digital signal processor (DSP) plus circuitry that implements voice-recognition and spectral- manipulation techniques. The development of the adaptive noise-suppression subsystem was prompted by the following considerations: During processing of the space shuttle at Kennedy Space Center, voice communications among test team members have been significantly impaired in several instances because some test participants have had to communicate from locations with high ambient noise levels. Ear protection for the personnel involved is commercially available and is used in such situations. However, commercially available noise-canceling microphones do not provide sufficient reduction of noise that enters through microphones and thus becomes transmitted on outbound communication links.

  3. Suppression of Bedbug's Reproduction by RNA Interference of Vitellogenin.

    PubMed

    Moriyama, Minoru; Hosokawa, Takahiro; Tanahashi, Masahiko; Nikoh, Naruo; Fukatsu, Takema

    2016-01-01

    Recent resurgence of the bedbug Cimex lectularius is a global problem on the public health. On account of the worldwide rise of insecticide-resistant bedbug populations, exploration of new approaches to the bedbug control and management is anticipated. In this context, gene silencing by RNA interference (RNAi) has been considered for its potential application to pest control and management, because RNAi enables specific suppression of target genes and thus flexible selection of target traits to be disrupted. In this study, in an attempt to develop a control strategy targeting reproduction of the bedbug, we investigated RNAi-mediated gene silencing of vitellogenin (Vg), a major yolk protein precursor essential for oogenesis. From the bedbug transcriptomes, we identified a typical Vg gene and a truncated Vg gene, which were designated as ClVg and ClVg-like, respectively. ClVg gene was highly expressed mainly in the fat body of adult females, which was more than 100 times higher than the expression level of ClVg-like gene, indicating that ClVg gene is the primary functional Vg gene in the bedbug. RNAi-mediated suppression of ClVg gene expression in adult females resulted in drastically reduced egg production, atrophied ovaries, and inflated abdomen due to hypertrophied fat bodies. These phenotypic consequences are expected not only to suppress the bedbug reproduction directly but also to deteriorate its feeding and survival indirectly via behavioral modifications. These results suggest the potential of ClVg gene as a promising target for RNAi-based population management of the bedbug. PMID:27096422

  4. Interference and Shaping in Sensorimotor Adaptations with Rewards

    PubMed Central

    Darshan, Ran; Leblois, Arthur; Hansel, David

    2014-01-01

    When a perturbation is applied in a sensorimotor transformation task, subjects can adapt and maintain performance by either relying on sensory feedback, or, in the absence of such feedback, on information provided by rewards. For example, in a classical rotation task where movement endpoints must be rotated to reach a fixed target, human subjects can successfully adapt their reaching movements solely on the basis of binary rewards, although this proves much more difficult than with visual feedback. Here, we investigate such a reward-driven sensorimotor adaptation process in a minimal computational model of the task. The key assumption of the model is that synaptic plasticity is gated by the reward. We study how the learning dynamics depend on the target size, the movement variability, the rotation angle and the number of targets. We show that when the movement is perturbed for multiple targets, the adaptation process for the different targets can interfere destructively or constructively depending on the similarities between the sensory stimuli (the targets) and the overlap in their neuronal representations. Destructive interferences can result in a drastic slowdown of the adaptation. As a result of interference, the time to adapt varies non-linearly with the number of targets. Our analysis shows that these interferences are weaker if the reward varies smoothly with the subject's performance instead of being binary. We demonstrate how shaping the reward or shaping the task can accelerate the adaptation dramatically by reducing the destructive interferences. We argue that experimentally investigating the dynamics of reward-driven sensorimotor adaptation for more than one sensory stimulus can shed light on the underlying learning rules. PMID:24415925

  5. Regularized Estimate of the Weight Vector of an Adaptive Interference Canceller

    NASA Astrophysics Data System (ADS)

    Ermolayev, V. T.; Sorokin, I. S.; Flaksman, A. G.; Yastrebov, A. V.

    2016-05-01

    We consider an adaptive multi-channel interference canceller, which ensures the minimum value of the average output power of interference. It is proposed to form the weight vector of such a canceller as the power-vector expansion. It is shown that this approach allows one to obtain an exact analytical solution for the optimal weight vector by using the procedure of the power-vector orthogonalization. In the case of a limited number of the input-process samples, the solution becomes ill-defined and its regularization is required. An effective regularization method, which ensures a high degree of the interference suppression and does not involve the procedure of inversion of the correlation matrix of interference, is proposed, which significantly reduces the computational cost of the weight-vector estimation.

  6. Regularized Estimate of the Weight Vector of an Adaptive Interference Canceller

    NASA Astrophysics Data System (ADS)

    Ermolayev, V. T.; Sorokin, I. S.; Flaksman, A. G.; Yastrebov, A. V.

    2016-06-01

    We consider an adaptive multi-channel interference canceller, which ensures the minimum value of the average output power of interference. It is proposed to form the weight vector of such a canceller as the power-vector expansion. It is shown that this approach allows one to obtain an exact analytical solution for the optimal weight vector by using the procedure of the power-vector orthogonalization. In the case of a limited number of the input-process samples, the solution becomes ill-defined and its regularization is required. An effective regularization method, which ensures a high degree of the interference suppression and does not involve the procedure of inversion of the correlation matrix of interference, is proposed, which significantly reduces the computational cost of the weight-vector estimation.

  7. Computerized Testing Software for Assessing Interference Suppression in Children and Adults: The Bivalent Shape Task (BST)

    PubMed Central

    Mueller, Shane T.; Esposito, Alena G.

    2015-01-01

    We describe the Bivalent Shape Task (BST), software using the Psychology Experiment Building Language (PEBL), for testing of cognitive interference and the ability to suppress interference. The test is available via the GNU Public License, Version 3 (GPLv3), is freely modifiable, and has been tested on both children and adults and found to provide a simple and fast non-verbal measure of cognitive interference and suppression that requires no reading. PMID:26702358

  8. Retrieval Induces Adaptive Forgetting of Competing Memories via Cortical Pattern Suppression

    PubMed Central

    Wimber, Maria; Alink, Arjen; Charest, Ian; Kriegeskorte, Nikolaus; Anderson, Michael C.

    2015-01-01

    Remembering a past experience can, surprisingly, cause forgetting. Forgetting arises when other competing traces interfere with retrieval, and inhibitory control mechanisms are engaged to suppress the distraction they cause. This form of forgetting is considered adaptive because it reduces future interference. The impact of this proposed inhibition process on competing memories has, however, never been observed both because behavioural methods are “blind” to retrieval dynamics and because neuroimaging methods have not isolated retrieval of individual memories. Here we introduce a canonical template tracking method to quantify the activation state of individual target memories and competitors during retrieval. This method revealed that repeatedly retrieving target memories suppressed cortical patterns unique to competitors. Pattern suppression was related to engagement of prefrontal regions implicated in resolving retrieval competition, and, critically, predicted later forgetting. We thus demonstrate a cortical pattern suppression mechanism through which remembering adaptively shapes which aspects of our past remain accessible. PMID:25774450

  9. Conditions for Interference Versus Facilitation During Sequential Sensorimotor Adaptation

    NASA Technical Reports Server (NTRS)

    Bock, Otmar; Schneider, Stefan; Bloomberg, Jacob

    2001-01-01

    We investigated how sensorimotor adaptation acquired during one experimental session influenced the adaptation in a subsequent session. The subjects' task was to track a visual target using a joystick-controlled cursor, while the relationship between joystick and cursor position was manipulated to introduce a sensorimotor discordance. Each subject participated in two sessions, separated by a pause of 2 min to 1 month duration. We found that adaptation was achieved within minutes, and persisted in the memory for at least a month, with only a small decay (experiment A). When the discordances administered in the two sessions were in mutual conflict, we found evidence for task interference (experiment B). However, when the discordances were independent, we found facilitation rather than interference (experiment C); the latter finding could not be explained by the use of an "easier" discordance in the second session (experiment D). We conclude that interference is due to an incompatibility between task requirements, and not to a competition of tasks for short-term memory. We further conclude that the ability to adapt to a sensorimotor discordance.

  10. UAV visual signature suppression via adaptive materials

    NASA Astrophysics Data System (ADS)

    Barrett, Ron; Melkert, Joris

    2005-05-01

    Visual signature suppression (VSS) methods for several classes of aircraft from WWII on are examined and historically summarized. This study shows that for some classes of uninhabited aerial vehicles (UAVs), primary mission threats do not stem from infrared or radar signatures, but from the amount that an aircraft visually stands out against the sky. The paper shows that such visual mismatch can often jeopardize mission success and/or induce the destruction of the entire aircraft. A psycho-physioptical study was conducted to establish the definition and benchmarks of a Visual Cross Section (VCS) for airborne objects. This study was centered on combining the effects of size, shape, color and luminosity or effective illumance (EI) of a given aircraft to arrive at a VCS. A series of tests were conducted with a 6.6ft (2m) UAV which was fitted with optically adaptive electroluminescent sheets at altitudes of up to 1000 ft (300m). It was shown that with proper tailoring of the color and luminosity, the VCS of the aircraft dropped from more than 4,200cm2 to less than 1.8cm2 at 100m (the observed lower limit of the 20-20 human eye in this study). In laypersons terms this indicated that the UAV essentially "disappeared". This study concludes with an assessment of the weight and volume impact of such a Visual Suppression System (VSS) on the UAV, showing that VCS levels on this class UAV can be suppressed to below 1.8cm2 for aircraft gross weight penalties of only 9.8%.

  11. Adaptive filters for suppressing irregular hostile jamming in direct sequence spread-spectrum system

    NASA Astrophysics Data System (ADS)

    Lee, Jung Hoon; Lee, Choong Woong

    A stable and high-performance adaptive filter for suppressing irregular hostile jamming in direct-sequence (DS) spread-spectrum systems is designed. A gradient-search fast converging algorithm (GFC) is suggested. For the case of a sudden parameter jump or incoming of an interference, the transient behaviors of the receiver using a GFC adaptive filter are investigated and compared with those of the receiver using a least-mean-square (LMS) or a lattice adaptive filter. The results are shown in the response graphs of the simulated receiver during the short period when the characteristic of a jammer is suddenly changed. Steady-state performances of those receivers are also evaluated in the sense of the excess mean-square error over that of an optimum receiver for suppressing stationary interferences.

  12. Interference suppression for 121.5/243 MHz SARSAT signals

    NASA Astrophysics Data System (ADS)

    Sun, Xiangqun

    2000-12-01

    When an aircraft or marine vessel is in distress, the emergency unit is activated either automatically or by manually setting a switch. The signal is then received by an orbiting satellite as it sweeps out a path over the search and rescue satellite aided tracking (SARSAT) region of interest. Due to the relative motion between the satellite and the Emergency Locator Transmitter (ELT) or the Emergency Position Indicating Radio Beacon (EPIRB) unit, the signal received at the spacecraft is Doppler shifted. New processing techniques for detecting ELT signals in an interfering background are investigated, based on not only computer simulations but also experimental data. The new methods involve the use of the Geometrically Averaged Spectrum (GAS) and the Harmonically Averaged Spectrum (HAS) in addition to the Arithmetically Averaged Spectrum (AAS) adopted by the existing system. Specifically, this thesis investigates the theoretical performance of AAS, GAS and HAS averaging in practical circumstances involving signals, noise and interference. It is shown that the carrier peaks of good ELT signals can be substantially enhanced in an interfering background. The treatise identifies certain types of interference such as Carrier interference with strong or weak AM, On-Off Modulation interference, Swept Carrier interference, and Ringing Response interference. Using computer simulation, it is demonstrated that under certain conditions the effects of background interference can be greatly reduced and the detection of ELT carrier peaks can be improved by employing a combination of AAS, GAS and HAS averaging. Real SARSAT pass data signals are fed into the computer and processed using AAS, GAS and HAS averaging. The background interference postulated in this thesis is found to exist and real ELT signals are identified. ELT signals representing the NIC model and a new model, called the Frequency Modulated ELT (FME) model, are identified along with a new ELT signal for which a model

  13. Adapting populations in space: clonal interference and genetic diversity

    NASA Astrophysics Data System (ADS)

    Weissman, Daniel; Barton, Nick

    Most species inhabit ranges much larger than the scales over which individuals interact. How does this spatial structure interact with adaptive evolution? We consider a simple model of a spatially-extended, adapting population and show that, while clonal interference severely limits the adaptation of purely asexual populations, even rare recombination is enough to allow adaptation at rates approaching those of well-mixed populations. We also find that the genetic hitchhiking produced by the adaptive alleles sweeping through the population has strange effects on the patterns of genetic diversity. In large spatial ranges, even low rates of adaptation cause all individuals in the population to rapidly trace their ancestry back to individuals living in a small region in the center of the range. The probability of fixation of an allele is thus strongly dependent on the allele's spatial location, with alleles from the center favored. Surprisingly, these effects are seen genome-wide (instead of being localized to the regions of the genome undergoing the sweeps). The spatial concentration of ancestry produces a power-law dependence of relatedness on distance, so that even individuals sampled far apart are likely to be fairly closely related, masking the underlying spatial structure.

  14. Interocular suppression prevents interference in a flanker task.

    PubMed

    Wu, Qiong; Lo Voi, Jonathan T H; Lee, Thomas Y; Mackie, Melissa-Ann; Wu, Yanhong; Fan, Jin

    2015-01-01

    Executive control of attention refers to processes that detect and resolve conflict among competing thoughts and actions. Despite the high-level nature of this faculty, the role of awareness in executive control of attention is not well understood. In this study, we used interocular suppression to mask the flankers in an arrow flanker task, in which the flankers and the target arrow were presented simultaneously in order to elicit executive control of attention. Participants were unable to detect the flanker arrows or to reliably identify their direction when masked. There was a typical conflict effect (prolonged reaction time and increased error rate under flanker-target incongruent condition compared to congruent condition) when the flanker arrows were unmasked, while the conflict effect was absent when the flanker arrows were masked with interocular suppression. These results suggest that blocking awareness of competing stimuli with interocular suppression prevents the involvement of executive control of attention. PMID:26321969

  15. Spatial suppression of interference in hybrid reflector antennas*

    NASA Astrophysics Data System (ADS)

    Kartsan, N.; Zelenkov, P. V.; Tyapkin, V. N.; Dmitriev, D. D.; Goncharov, E.

    2016-04-01

    The article describes a 7-beam hybrid reflector antenna with a 19-element feed element which forms a radiation pattern in the form of a cluster. During the research the synthesis of the amplitude-phase distribution of the antenna feed element has been conducted. A radiation pattern for three situations of interference: along the first side lobe, along the ramp of the main lobe, along the main lobe.

  16. Microwave Photonic Filters for Interference Cancellation and Adaptive Beamforming

    NASA Astrophysics Data System (ADS)

    Chang, John

    Wireless communication has experienced an explosion of growth, especially in the past half- decade, due to the ubiquity of wireless devices, such as tablets, WiFi-enabled devices, and especially smartphones. Proliferation of smartphones with powerful processors and graphic chips have given an increasing amount of people the ability to access anything from anywhere. Unfortunately, this ease of access has greatly increased mobile wireless bandwidth and have begun to stress carrier networks and spectra. Wireless interference cancellation will play a big role alongside the popularity of wire- less communication. In this thesis, we will investigate optical signal processing methods for wireless interference cancellation methods. Optics provide the perfect backdrop for interference cancellation. Mobile wireless data is already aggregated and transported through fiber backhaul networks in practice. By sandwiching the signal processing stage between the receiver and the fiber backhaul, processing can easily be done locally in one location. Further, optics offers the advantages of being instantaneously broadband and size, weight, and power (SWAP). We are primarily concerned with two methods for interference cancellation, based on microwave photonic filters, in this thesis. The first application is for a co-channel situation, in which a transmitter and receiver are co-located and transmitting at the same frequency. A novel analog optical technique extended for multipath interference cancellation of broadband signals is proposed and experimentally demonstrated in this thesis. The proposed architecture was able to achieve a maximum of 40 dB of cancellation over 200 MHz and 50 dB of cancellation over 10 MHz. The broadband nature of the cancellation, along with its depth, demonstrates both the precision of the optical components and the validity of the architecture. Next, we are interested in a scenario with dynamically changing interference, which requires an adaptive photonic

  17. Signal enhancement and background suppression using interference and entanglement

    SciTech Connect

    Kastella, Keith; Conti, Ralph S.

    2011-01-15

    We describe two-photon absorption processes excited by entangled pairs but not by nonentangled pairs of the same energy and polarization. Photon states are selected for destructive interference in the nonentangled process between different sequences of absorption via multiple intermediate states. A nonzero entangled absorption cross section is obtained by varying the entanglement time and pair delay parameters. Detailed energy and polarization requirements are derived for Rb 5S{sub 1/2}-5D{sub 3/2} transitions. Applications to quantum steganography, quantum illumination, and quantum key distribution are discussed.

  18. A Comparative Study of Co-Channel Interference Suppression Techniques

    NASA Technical Reports Server (NTRS)

    Hamkins, Jon; Satorius, Ed; Paparisto, Gent; Polydoros, Andreas

    1997-01-01

    We describe three methods of combatting co-channel interference (CCI): a cross-coupled phase-locked loop (CCPLL); a phase-tracking circuit (PTC), and joint Viterbi estimation based on the maximum likelihood principle. In the case of co-channel FM-modulated voice signals, the CCPLL and PTC methods typically outperform the maximum likelihood estimators when the modulation parameters are dissimilar. However, as the modulation parameters become identical, joint Viterbi estimation provides for a more robust estimate of the co-channel signals and does not suffer as much from "signal switching" which especially plagues the CCPLL approach. Good performance for the PTC requires both dissimilar modulation parameters and a priori knowledge of the co-channel signal amplitudes. The CCPLL and joint Viterbi estimators, on the other hand, incorporate accurate amplitude estimates. In addition, application of the joint Viterbi algorithm to demodulating co-channel digital (BPSK) signals in a multipath environment is also discussed. It is shown in this case that if the interference is sufficiently small, a single trellis model is most effective in demodulating the co-channel signals.

  19. Interference between adaptation to double steps and adaptation to rotated feedback in spite of differences in directional selectivity.

    PubMed

    Schmitz, Gerd

    2016-06-01

    Two key features of sensorimotor adaptation are the directional selectivity of adaptive changes and the interference of adaptations to opposite directions. The present study investigated whether directional selectivity and interference of adaptation are related to executive functions and whether these phenomena differ between two methods for visuomotor adaptation. Subjects adapted at three target directions to clockwise or counterclockwise rotated feedback or to clockwise or counterclockwise target displacements (double steps). Both adaptation methods induce rotations of movement trajectories into the same direction, but provide visual information differently. The results showed that adaptation progressed differently between three targets. When movements adapted clockwise, adaptation was best at the most clockwise located target, and when movements adapted counterclockwise, it was best at the most counterclockwise located target, suggesting that spatial generalization between target directions is related to the direction of motor adaptation. The two adaptation methods produced different adaptation patterns, which indicate a further impact of visual information. A second adaptation to the other and opposite-directed discordance was worse than naive adaptation and washed out the aftereffects from the first adaptation, confirming that both adaptation methods interfered. Executive functions were significant covariate for overall interference and interference of target-specific adaptation. The results suggest that directional selectivity of adaptation is shaped by the direction of motor adaptation and the visual information provided. The interference of both adaptation methods indicates that they share adaptive mechanisms for recalibration. The interference is the lower the better subjects are able to cognitively switch between tasks and to inhibit prepotent responses. Therefore, cognitive functions seem to be involved in the inhibition of non-adequate sensorimotor

  20. Antireflection effects at nanostructured material interfaces and the suppression of thin-film interference

    NASA Astrophysics Data System (ADS)

    Yang, Qiaoyin; Zhang, Xu A.; Bagal, Abhijeet; Guo, Wei; Chang, Chih-Hao

    2013-06-01

    Thin-film interference is a well-known effect, and it is commonly observed in the colored appearance of many natural phenomena. Caused by the interference of light reflected from the interfaces of thin material layers, such interference effects can lead to wavelength and angle-selective behavior in thin-film devices. In this work, we describe the use of interfacial nanostructures to eliminate interference effects in thin films. Using the same principle inspired by moth-eye structures, this approach creates an effective medium where the index is gradually varying between the neighboring materials. We present the fabrication process for such nanostructures at a polymer-silicon interface, and experimentally demonstrate its effectiveness in suppressing thin-film interference. The principle demonstrated in this work can lead to enhanced efficiency and reduce wavelength/angle sensitivity in multilayer optoelectronic devices.

  1. Distinct Neural Correlates for Two Types of Inhibition in Bilinguals: Response Inhibition versus Interference Suppression

    ERIC Educational Resources Information Center

    Luk, Gigi; Anderson, John A. E.; Craik, Fergus I. M.; Grady, Cheryl; Bialystok, Ellen

    2010-01-01

    To examine the effects of bilingualism on cognitive control, we studied monolingual and bilingual young adults performing a flanker task with functional MRI. The trial types of primary interest for this report were incongruent and no-go trials, representing interference suppression and response inhibition, respectively. Response times were similar…

  2. Suppression of Strong Background Interference on E-Nose Sensors in an Open Country Environment

    PubMed Central

    Tian, Fengchun; Zhang, Jian; Yang, Simon X.; Zhao, Zhenzhen; Liang, Zhifang; Liu, Yan; Wang, Di

    2016-01-01

    The feature extraction technique for an electronic nose (e-nose) applied in tobacco smell detection in an open country/outdoor environment with periodic background strong interference is studied in this paper. Principal component analysis (PCA), Independent component analysis (ICA), re-filtering and a priori knowledge are combined to separate and suppress background interference on the e-nose. By the coefficient of multiple correlation (CMC), it can be verified that a better separation of environmental temperature, humidity, and atmospheric pressure variation related background interference factors can be obtained with ICA. By re-filtering according to the on-site interference characteristics a composite smell curve was obtained which is more related to true smell information based on the tobacco curer’s experience. PMID:26891302

  3. Enhancement and suppression in a lexical interference fMRI-paradigm.

    PubMed

    Abel, Stefanie; Dressel, Katharina; Weiller, Cornelius; Huber, Walter

    2012-03-01

    Previous picture-word interference (PWI) fMRI-paradigms revealed ambiguous mechanisms underlying facilitation and inhibition in healthy subjects. Lexical distractors revealed increased (enhancement) or decreased (suppression) activation in language and monitoring/control areas. Performing a secondary examination and data analysis, we aimed to illuminate the relation between behavioral and neural interference effects comparing target-related distractors (REL) with unrelated distractors (UNREL). We hypothesized that interference involves both (A) suppression due to priming and (B) enhancement due to simultaneous distractor and target processing. Comparisons to UNREL should remain distractor unspecific even at a low threshold. (C) Distractor types with common characteristics should reveal overlapping brain areas. In a 3T MRI scanner, participants were asked to name pictures while auditory words were presented (stimulus onset asynchrony [SOA] = -200 msec). Associatively and phonologically related distractors speeded responses (facilitation), while categorically related distractors slowed them down (inhibition) compared to UNREL. As a result, (A) reduced brain activations indeed resembled previously reported patterns of neural priming. Each target-related distractor yielded suppressions at least in areas associated with vision and conflict/competition monitoring (anterior cingulate cortex [ACC]), revealing least priming for inhibitors. (B) Enhancements concerned language-related but distractor-unspecific regions. (C) Some wider brain regions were commonly suppressed for combinations of distractor types. Overlapping areas associated with conceptual priming were found for facilitatory distractors (inferior frontal gyri), and areas related to phonetic/articulatory processing (precentral gyri and left parietal operculum/insula) for distractors sharing feature overlap. Each distractor with semantic relatedness revealed nonoverlapping suppressions in lexical

  4. Adaptive Noise Suppression Using Digital Signal Processing

    NASA Technical Reports Server (NTRS)

    Kozel, David; Nelson, Richard

    1996-01-01

    A signal to noise ratio dependent adaptive spectral subtraction algorithm is developed to eliminate noise from noise corrupted speech signals. The algorithm determines the signal to noise ratio and adjusts the spectral subtraction proportion appropriately. After spectra subtraction low amplitude signals are squelched. A single microphone is used to obtain both eh noise corrupted speech and the average noise estimate. This is done by determining if the frame of data being sampled is a voiced or unvoiced frame. During unvoice frames an estimate of the noise is obtained. A running average of the noise is used to approximate the expected value of the noise. Applications include the emergency egress vehicle and the crawler transporter.

  5. Communication system with adaptive noise suppression

    NASA Technical Reports Server (NTRS)

    Kozel, David (Inventor); Devault, James A. (Inventor); Birr, Richard B. (Inventor)

    2007-01-01

    A signal-to-noise ratio dependent adaptive spectral subtraction process eliminates noise from noise-corrupted speech signals. The process first pre-emphasizes the frequency components of the input sound signal which contain the consonant information in human speech. Next, a signal-to-noise ratio is determined and a spectral subtraction proportion adjusted appropriately. After spectral subtraction, low amplitude signals can be squelched. A single microphone is used to obtain both the noise-corrupted speech and the average noise estimate. This is done by determining if the frame of data being sampled is a voiced or unvoiced frame. During unvoiced frames an estimate of the noise is obtained. A running average of the noise is used to approximate the expected value of the noise. Spectral subtraction may be performed on a composite noise-corrupted signal, or upon individual sub-bands of the noise-corrupted signal. Pre-averaging of the input signal's magnitude spectrum over multiple time frames may be performed to reduce musical noise.

  6. Suppression of interference in quantum Hall Mach-Zehnder geometry by upstream neutral modes

    NASA Astrophysics Data System (ADS)

    Gefen, Yuval; Goldstein, Moshe

    Mach-Zehnder interferometry has been suggested as a probe for anyonic quasiparticles in fractional quantum Hall states. However, all experimental attempts to measure such an interference signal have failed to date, despite the high visibility of interference fringes in the integer quantum Hall case. In our work we have studied the relation between this null result and another recent surprising experimental finding, namely the detection of upstream neutral modes in virtually all fractional quantum Hall states (including, e.g., filling 1/3), not only in hole-like filling factors (such as 2/3). We have found that the excitation of upstream modes makes the interference visibility in the Mach-Zehnder geometry decay exponentially with the total length of the interferometer arms, even when the lengths are exactly equal. We also suggest ways to overcome this suppression.

  7. Adaptive arrays for satellite communications

    NASA Technical Reports Server (NTRS)

    Gupta, I. J.; Ksienski, A. A.

    1984-01-01

    The suppression of interfering signals in a satellite communication system was studied. Adaptive arrays are used to suppress interference at the reception site. It is required that the interference be suppressed to very low levels and a modified adaptive circuit is used which accomplishes the desired objective. Techniques for the modification of the transmit patterns to minimize interference with neighboring communication links are explored.

  8. Analysis of the Throughput of the Cellular Radio-Communication Systems Using Coordinated Data Transmission to Suppress Mutual Unintended Interference

    NASA Astrophysics Data System (ADS)

    Morozov, G. V.; Davydov, A. V.; Mal'tsev, A. A.

    2014-08-01

    We present the results of the comparative analysis of two data-transmission schemes of the fourth-generation cellular communication standard LTE-A, which use the "quasistatic" and "dynamic" coordination at the neighbor base stations. Both schemes are used to suppress mutual unintended co-channel interference resulting from the repeated use of one frequency channel by the neighbor base stations. The general case of the heterogeneous cellular radio-communication system with different station types (macro- and picostations) is considered. In this work, the efficiency of the coordinated-transmission schemes is studied along with the adaptive algorithms for the dataflow planning and control. The use of both coordination schemes is comparatively analyzed. An original algorithm for redistribution of the user connections is proposed for the dynamic scheme and the dependence of the communication-system throughput on the radio-network configuration and the number of base stations, that participate in the coordination is studied.

  9. SPECKLE NOISE SUBTRACTION AND SUPPRESSION WITH ADAPTIVE OPTICS CORONAGRAPHIC IMAGING

    SciTech Connect

    Ren Deqing; Dou Jiangpei; Zhang Xi; Zhu Yongtian

    2012-07-10

    Future ground-based direct imaging of exoplanets depends critically on high-contrast coronagraph and wave-front manipulation. A coronagraph is designed to remove most of the unaberrated starlight. Because of the wave-front error, which is inherit from the atmospheric turbulence from ground observations, a coronagraph cannot deliver its theoretical performance, and speckle noise will limit the high-contrast imaging performance. Recently, extreme adaptive optics, which can deliver an extremely high Strehl ratio, is being developed for such a challenging mission. In this publication, we show that barely taking a long-exposure image does not provide much gain for coronagraphic imaging with adaptive optics. We further discuss a speckle subtraction and suppression technique that fully takes advantage of the high contrast provided by the coronagraph, as well as the wave front corrected by the adaptive optics. This technique works well for coronagraphic imaging with conventional adaptive optics with a moderate Strehl ratio, as well as for extreme adaptive optics with a high Strehl ratio. We show how to substrate and suppress speckle noise efficiently up to the third order, which is critical for future ground-based high-contrast imaging. Numerical simulations are conducted to fully demonstrate this technique.

  10. Adaptive Instability Suppression Controls in a Liquid-fueled Combustor

    NASA Technical Reports Server (NTRS)

    Kopasakis, George; DeLaat, John C.

    2002-01-01

    An adaptive control algorithm has been developed for the suppression of combustion thermo-acoustic instabilities. This technique involves modulating the fuel flow in the combustor with a control phase that continuously slides within the stable phase region, in a back and forth motion. The control method is referred to as Adaptive Sliding Phasor Averaged Control (ASPAC). The control method is evaluated against a simplified simulation of the combustion instability. Plans are to validate the control approach against a more physics-based model and an actual experimental combustor rig.

  11. RF interference suppression in a cardiac synchronization system operating in a high magnetic field NMR imaging system

    SciTech Connect

    Damji, A.A.; Snyder, R.E.; Ellinger, D.C.; Witkowski, F.X.; Allen, P.S.

    1988-11-01

    An electrocardiographic (ECG) unit suitable for cardiac-synchronized nuclear magnetic resonance imaging in high magnetic fields is presented. The unit includes lossy transmission lines as ECG leads in order to suppress radio frequency (RF) interference in the electrocardiogram. The unit's immunity to RF interference is demonstrated.

  12. All-optical tunable microwave interference suppression filter based on SOA

    NASA Astrophysics Data System (ADS)

    Xu, Enming; Zhang, Xinliang; Zhou, Lina; Huang, Dexiu

    2008-12-01

    An all-optical filter structure for interference suppression of microwave signals is presented. The filter is based on a recirculating delay line (RDL) loop consisting of a semiconductor optical amplifier (SOA) followed by a tunable narrowband optical filter, and a fiber Bragg grating connected after the RDL loop. Negative tap is generated in wavelength conversion process based on cross-gain modulation of amplified spontaneous emission spectrum of the SOA. A narrow passband filter with negative coefficients and a broadband all-pass filter are synthesized to achieve a narrow notch filter with flat passband which can excise interference with minimal impact on the wanted signal over a wide microwave range. Experimental results show that measured and theoretical frequency responses agree well and the filter is tunable.

  13. GPS receiver algorithms for suppression of narrowband and structured wideband interference

    NASA Astrophysics Data System (ADS)

    Madhani, Premal Harish

    This dissertation describes algorithms that enhance the acquisition and tracking performance of a GPS receiver in the presence of narrowband and structured wideband interference. As GPS becomes an essential element of the civil infrastructure in the areas of aviation, ground transportation, communications, and power distribution, its vulnerability to interference must be addressed. Unintentional interference typically takes the form of a narrowband signal. Structured wideband interference can result from the ground-based augmentation of GPS with pseudolites. Algorithms that enhance performance for these two situations are developed and described in detail. Pseudolites are a very useful augmentation to GPS that provide enhanced coverage in areas of high blockage or for critical missions such as aircraft landing. However, pseudolites may introduce what is known as near-far interference, where a pseudolite signal interferes with the acquisition and tracking of weaker satellite signals. I have applied the technique of successive interference cancellation (SIC) to improve acquisition performance in the presence of a pseudolite signal. An extension of SIC to the identification and cancellation of pseudolite multipath is also given. The performance of these algorithms is demonstrated on simulated and experimental data, showing significant improvement over conventional techniques. The low level of GPS signals makes them susceptible to narrowband interference, despite the inherent resistance to interference afforded by GPS spread spectrum modulation. In my research I have investigated a number of algorithms that can increase the robustness of GPS receivers in a hostile narrowband electromagnetic environment. This dissertation describes several adaptive estimators which are applied to simulated GPS data. Comparisons are made in terms of post-correlation signal-to-noise ratio, tracking errors, and computational requirements. Conventional techniques of high accuracy Doppler

  14. Inter-band interference suppression in multi-band OFDM-PON uplink transmission using window shaping

    NASA Astrophysics Data System (ADS)

    Kim, Chang-Hun; Jung, Sang-Min; Jung, Sun-Young; Kang, Soo-Min; Han, Sang-Kook

    2016-01-01

    We propose window shaping based inter-band interference suppression technique in multi-band orthogonal frequency division multiple access (MB-OFDMA) based passive optical network (PON) system. Conventional MB-OFDMA and raised-cosine (RC) windowed MB-OFDMA were compared in QPSK transmission and adaptive modulation scenario. The effect of OFDM clipping ratio is analyzed, which is used to mitigate peak to average power ratio (PAPR) problem at the transmitter. Also, the MB-OFDMA based multiple access performance is investigated according to the different roll-off factor of RC window in terms of error vector magnitude (EVM) and effective bit rate. Compared with the conventional MB-OFDMA which is rectangular windowed, the RC-windowed MB-OFDMA shows better performance by suppressed sidelobe which leads to IBI. The maximum effective bit rate of 10 Gbps was achieved for 20 km transmission scenario at optimum roll-off factor, while it was 9 Gbps in the conventional MB-OFDMA transmission.

  15. Kalman filtering to suppress spurious signals in Adaptive Optics control

    SciTech Connect

    Poyneer, L; Veran, J P

    2010-03-29

    In many scenarios, an Adaptive Optics (AO) control system operates in the presence of temporally non-white noise. We use a Kalman filter with a state space formulation that allows suppression of this colored noise, hence improving residual error over the case where the noise is assumed to be white. We demonstrate the effectiveness of this new filter in the case of the estimated Gemini Planet Imager tip-tilt environment, where there are both common-path and non-common path vibrations. We discuss how this same framework can also be used to suppress spatial aliasing during predictive wavefront control assuming frozen flow in a low-order AO system without a spatially filtered wavefront sensor, and present experimental measurements from Altair that clearly reveal these aliased components.

  16. Orthogonal on-off control of radar pulses for the suppression of mutual interference

    NASA Astrophysics Data System (ADS)

    Kim, Yong Cheol

    1998-10-01

    Intelligent vehicles of the future will be guided by radars and other sensors to avoid obstacles. When multiple vehicles move simultaneously in autonomous navigational mode, mutual interference among car radars becomes a serious problem. An obstacle is illuminated with electromagnetic pulses from several radars. The signal at a radar receiver is actually a mixture of the self-reflection and the reflection of interfering pulses emitted by others. When standardized pulse- type radars are employed on vehicles for obstacle avoidance and so self-pulse and interfering pulses have identical pulse repetition interval, this SI (synchronous Interference) is very difficult to separate from the true reflection. We present a method of suppressing such a synchronous interference. By controlling the pulse emission of a radar in a binary orthogonal ON, OFF pattern, the true self-reflection can be separated from the false one. Two range maps are generated, TRM (true-reflection map) and SIM (synchronous- interference map). TRM is updated for every ON interval and SIM is updated for every OFF interval of the self-radar. SIM represents the SI of interfering radars while TRM keeps a record of a mixture of the true self-reflection and SI. Hence the true obstacles can be identified by the set subtraction operation. The performance of the proposed method is compared with that of the conventional M of N method. Bayesian analysis shows that the probability of false alarm is improved by order of 103 to approximately 106 while the deterioration in the probability of detection is negligible.

  17. Inter-limb interference during bimanual adaptation to dynamic environments

    PubMed Central

    Casadio, Maura; Sanguineti, Vittorio; Squeri, Valentina; Masia, Lorenzo; Morasso, Pietro

    2015-01-01

    Skillful manipulation of objects often requires the spatio-temporal coordination of both hands and, at the same time, the compensation of environmental forces. In bimanual coordination, movements of the two hands may be coupled because each hand needs to compensate the forces generated by the other hand or by an object operated by both hands (dynamic coupling), or because the two hands share the same workspace (spatial coupling). We examined how spatial coupling influences bimanual coordination, by looking at the adaptation of velocity-dependent force fields during a task in which the two hands simultaneously perform center-out reaching movements with the same initial position and the same targets, equally spaced on a circle. Subjects were randomly allocated to two groups, which differed in terms of the force fields they were exposed to: in one group (CW-CW), force fields had equal clockwise orientations in both hands; in the other group (CCW-CW), they had opposite orientations. In both groups, in randomly selected trials (catch trials) of the adaptation phase, the force fields were unexpectedly removed. Adaptation was quantified in terms of the changes of directional error for both hand trajectories. Bimanual coordination was quantified in terms of inter-limb longitudinal and sideways displacements, in force field and in catch trials. Experimental results indicate that both arms could simultaneously adapt to the two force fields. However, in the CCW-CW group, adaptation was incomplete for the movements from the central position to the more distant targets with respect to the body. In addition, in this group the left hand systematically leads in the movements toward targets on the left of the starting position, whereas the right hand leads in the movements to targets on the right. We show that these effects are due to a gradual sideways shift of the hands, so that during movements the left hand tends to consistently remain at the left of the right hand. These

  18. Digital lock-in techniques for adaptive power-line interference extraction.

    PubMed

    Dobrev, Dobromir; Neycheva, Tatyana; Mudrov, Nikolay

    2008-07-01

    This paper presents a simple digital approach for adaptive power-line (PL) or other periodic interference extraction. By means of two digital square (or sine) wave mixers, the real and imaginary parts of the interference are found, and the interference waveform is synthesized and finally subtracted. The described technique can be implemented in an open-loop architecture where the interference is synthesized as a complex sinusoid or in a closed-loop architecture for automatic phase and gain control. The same approach can be used for removal of the fundamental frequency of the PL interference as well as its higher harmonics. It is suitable for real-time operation with popular low-cost microcontrollers. PMID:18560061

  19. Between-Trial Forgetting Due to Interference and Time in Motor Adaptation.

    PubMed

    Kim, Sungshin; Oh, Youngmin; Schweighofer, Nicolas

    2015-01-01

    Learning a motor task with temporally spaced presentations or with other tasks intermixed between presentations reduces performance during training, but can enhance retention post training. These two effects are known as the spacing and contextual interference effect, respectively. Here, we aimed at testing a unifying hypothesis of the spacing and contextual interference effects in visuomotor adaptation, according to which forgetting between trials due to either spaced presentations or interference by another task will promote between-trial forgetting, which will depress performance during acquisition, but will promote retention. We first performed an experiment with three visuomotor adaptation conditions: a short inter-trial-interval (ITI) condition (SHORT-ITI); a long ITI condition (LONG-ITI); and an alternating condition with two alternated opposite tasks (ALT), with the same single-task ITI as in LONG-ITI. In the SHORT-ITI condition, there was fastest increase in performance during training and largest immediate forgetting in the retention tests. In contrast, in the ALT condition, there was slowest increase in performance during training and little immediate forgetting in the retention tests. Compared to these two conditions, in the LONG-ITI, we found intermediate increase in performance during training and intermediate immediate forgetting. To account for these results, we fitted to the data six possible adaptation models with one or two time scales, and with interference in the fast, or in the slow, or in both time scales. Model comparison confirmed that two time scales and some degree of interferences in either time scale are needed to account for our experimental results. In summary, our results suggest that retention following adaptation is modulated by the degree of between-trial forgetting, which is due to time-based decay in single adaptation task and interferences in multiple adaptation tasks. PMID:26599075

  20. Fungal small RNAs suppress plant immunity by hijacking host RNA interference pathways.

    PubMed

    Weiberg, Arne; Wang, Ming; Lin, Feng-Mao; Zhao, Hongwei; Zhang, Zhihong; Kaloshian, Isgouhi; Huang, Hsien-Da; Jin, Hailing

    2013-10-01

    Botrytis cinerea, the causative agent of gray mold disease, is an aggressive fungal pathogen that infects more than 200 plant species. Here, we show that some B. cinerea small RNAs (Bc-sRNAs) can silence Arabidopsis and tomato genes involved in immunity. These Bc-sRNAs hijack the host RNA interference (RNAi) machinery by binding to Arabidopsis Argonaute 1 (AGO1) and selectively silencing host immunity genes. The Arabidopsis ago1 mutant exhibits reduced susceptibility to B. cinerea, and the B. cinerea dcl1 dcl2 double mutant that can no longer produce these Bc-sRNAs displays reduced pathogenicity on Arabidopsis and tomato. Thus, this fungal pathogen transfers "virulent" sRNA effectors into host plant cells to suppress host immunity and achieve infection, which demonstrates a naturally occurring cross-kingdom RNAi as an advanced virulence mechanism. PMID:24092744

  1. A New Approach to Interference Excision in Radio Astronomy: Real-Time Adaptive Cancellation

    NASA Astrophysics Data System (ADS)

    Barnbaum, Cecilia; Bradley, Richard F.

    1998-11-01

    Every year, an increasing amount of radio-frequency (RF) spectrum in the VHF, UHF, and microwave bands is being utilized to support new commercial and military ventures, and all have the potential to interfere with radio astronomy observations. Such services already cause problems for radio astronomy even in very remote observing sites, and the potential for this form of light pollution to grow is alarming. Preventive measures to eliminate interference through FCC legislation and ITU agreements can be effective; however, many times this approach is inadequate and interference excision at the receiver is necessary. Conventional techniques such as RF filters, RF shielding, and postprocessing of data have been only somewhat successful, but none has been sufficient. Adaptive interference cancellation is a real-time approach to interference excision that has not been used before in radio astronomy. We describe here, for the first time, adaptive interference cancellation in the context of radio astronomy instrumentation, and we present initial results for our prototype receiver. In the 1960s, analog adaptive interference cancelers were developed that obtain a high degree of cancellation in problems of radio communications and radar. However, analog systems lack the dynamic range, noised performance, and versatility required by radio astronomy. The concept of digital adaptive interference cancellation was introduced in the mid-1960s as a way to reduce unwanted noise in low-frequency (audio) systems. Examples of such systems include the canceling of maternal ECG in fetal electrocardiography and the reduction of engine noise in the passenger compartments of automobiles. These audio-frequency applications require bandwidths of only a few tens of kilohertz. Only recently has high-speed digital filter technology made high dynamic range adaptive canceling possible in a bandwidth as large as a few megahertz, finally opening the door to application in radio astronomy. We have

  2. Digital Terrestrial Video Broadcast Interference Suppression in Forward-Looking Ground Penetrating Radar Systems

    NASA Astrophysics Data System (ADS)

    Rial, F. I.; Mendez-Rial, Roi; Lawadka, Lukasz; Gonzalez-Huici, Maria A.

    2014-11-01

    In this paper we show how radio frequency interference (RFI) generated by digital video broadcasting terrestrial and digital audio broadcasting transmitters can be an important noise source for forward-looking ground penetrating radar (FLGPR) systems. Even in remote locations the average interference power sometimes exceeds ultra-wideband signals by many dB, becoming the limiting factor in the system sensitivity. The overall problem of RFI and its impact in GPR systems is briefly described and several signal processing approaches to removal of RFI are discussed. These include spectral estimation and coherent subtraction algorithms and various filter approaches which have been developed and applied by the research community in similar contexts. We evaluate the performance of these methods by simulating two different scenarios submitted to real RFI acquired with a FLGPR system developed at the Fraunhofer Institute for High Frequency Physics and Radar Techniques (FHR), (GER). The effectiveness of these algorithms in removing RFI is presented using some performance indices after suppression.

  3. Suppression of Bedbug’s Reproduction by RNA Interference of Vitellogenin

    PubMed Central

    Moriyama, Minoru; Hosokawa, Takahiro; Tanahashi, Masahiko; Nikoh, Naruo; Fukatsu, Takema

    2016-01-01

    Recent resurgence of the bedbug Cimex lectularius is a global problem on the public health. On account of the worldwide rise of insecticide-resistant bedbug populations, exploration of new approaches to the bedbug control and management is anticipated. In this context, gene silencing by RNA interference (RNAi) has been considered for its potential application to pest control and management, because RNAi enables specific suppression of target genes and thus flexible selection of target traits to be disrupted. In this study, in an attempt to develop a control strategy targeting reproduction of the bedbug, we investigated RNAi-mediated gene silencing of vitellogenin (Vg), a major yolk protein precursor essential for oogenesis. From the bedbug transcriptomes, we identified a typical Vg gene and a truncated Vg gene, which were designated as ClVg and ClVg-like, respectively. ClVg gene was highly expressed mainly in the fat body of adult females, which was more than 100 times higher than the expression level of ClVg-like gene, indicating that ClVg gene is the primary functional Vg gene in the bedbug. RNAi-mediated suppression of ClVg gene expression in adult females resulted in drastically reduced egg production, atrophied ovaries, and inflated abdomen due to hypertrophied fat bodies. These phenotypic consequences are expected not only to suppress the bedbug reproduction directly but also to deteriorate its feeding and survival indirectly via behavioral modifications. These results suggest the potential of ClVg gene as a promising target for RNAi-based population management of the bedbug. PMID:27096422

  4. Chemical Interference with Iron Transport Systems to Suppress Bacterial Growth of Streptococcus pneumoniae

    PubMed Central

    Zhang, Liang; Li, Nan; Han, Junlong; Zhang, Jing; Sun, Xuesong; He, Qing-Yu

    2014-01-01

    Iron is an essential nutrient for the growth of most bacteria. To obtain iron, bacteria have developed specific iron-transport systems located on the membrane surface to uptake iron and iron complexes such as ferrichrome. Interference with the iron-acquisition systems should be therefore an efficient strategy to suppress bacterial growth and infection. Based on the chemical similarity of iron and ruthenium, we used a Ru(II) complex R-825 to compete with ferrichrome for the ferrichrome-transport pathway in Streptococcus pneumoniae. R-825 inhibited the bacterial growth of S. pneumoniae and stimulated the expression of PiuA, the iron-binding protein in the ferrichrome-uptake system on the cell surface. R-825 treatment decreased the cellular content of iron, accompanying with the increase of Ru(II) level in the bacterium. When the piuA gene (SPD_0915) was deleted in the bacterium, the mutant strain became resistant to R-825 treatment, with decreased content of Ru(II). Addition of ferrichrome can rescue the bacterial growth that was suppressed by R-825. Fluorescence spectral quenching showed that R-825 can bind with PiuA in a similar pattern to the ferrichrome-PiuA interaction in vitro. These observations demonstrated that Ru(II) complex R-825 can compete with ferrichrome for the ferrichrome-transport system to enter S. pneumoniae, reduce the cellular iron supply, and thus suppress the bacterial growth. This finding suggests a novel antimicrobial approach by interfering with iron-uptake pathways, which is different from the mechanisms used by current antibiotics. PMID:25170896

  5. An experimental study of wall adaptation and interference assessment using Cauchy integral formula

    NASA Technical Reports Server (NTRS)

    Murthy, A. V.

    1991-01-01

    This paper summarizes the results of an experimental study of combined wall adaptation and residual interference assessment using the Cauchy integral formula. The experiments were conducted on a supercritical airfoil model in the Langley 0.3-m Transonic Cryogenic Tunnel solid flexible wall test section. The ratio of model chord to test section height was about 0.7. The method worked satisfactorily in reducing the blockage interference and demonstrated the primary requirement for correcting for the blockage effects at high model incidences to correctly determine high lift characteristics. The studies show that the method has potential for reducing the residual interference to considerably low levels. However, corrections to blockage and upwash velocities gradients may still be required for the final adapted wall shapes.

  6. Suppression of Speckles at High Adaptive Correction Using Speckle Symmetry

    NASA Technical Reports Server (NTRS)

    Bloemhof, Eric E.

    2006-01-01

    Focal-plane speckles set important sensitivity limits on ground- or space-based imagers and coronagraphs that may be used to search for faint companions, perhaps ultimately including exoplanets, around stars. As speckles vary with atmospheric fluctuations or with drifting beamtrain aberrations, they contribute speckle noise proportional to their full amplitude. Schemes to suppress speckles are thus of great interest. At high adaptive correction, speckles organize into species, represented by algebraic terms in the expansion of the phase exponential, that have distinct spatial symmetry, even or odd, under spatial inversion. Filtering speckle patterns by symmetry may eliminate a disproportionate fraction of the speckle noise while blocking (only) half of the image signal from the off-axis companion being sought. The fraction of speckle power and hence of speckle noise in each term will vary with degree of correction, and so also will the net symmetry in the speckle pattern.

  7. Enhancing nuclear quadrupole resonance (NQR) signature detection leveraging interference suppression algorithms

    NASA Astrophysics Data System (ADS)

    DeBardelaben, James A.; Miller, Jeremy K.; Myrick, Wilbur L.; Miller, Joel B.; Gilbreath, G. Charmaine; Bajramaj, Blerta

    2012-06-01

    Nuclear quadrupole resonance (NQR) is a radio frequency (RF) magnetic spectroscopic technique that has been shown to detect and identify a wide range of explosive materials containing quadrupolar nuclei. The NQR response signal provides a unique signature of the material of interest. The signal is, however, very weak and can be masked by non-stationary RF interference (RFI) and thermal noise, limiting detection distance. In this paper, we investigate the bounds on the NQR detection range for ammonium nitrate. We leverage a low-cost RFI data acquisition system composed of inexpensive B-field sensing and commercial-off-the-shelf (COTS) software-defined radios (SDR). Using collected data as RFI reference signals, we apply adaptive filtering algorithms to mitigate RFI and enable NQR detection techniques to approach theoretical range bounds in tactical environments.

  8. Consolidation through the looking-glass: sleep-dependent proactive interference on visuomotor adaptation in children.

    PubMed

    Urbain, Charline; Houyoux, Emeline; Albouy, Geneviève; Peigneux, Philippe

    2014-02-01

    Although a beneficial role of post-training sleep for declarative memory has been consistently evidenced in children, as in adults, available data suggest that procedural memory consolidation does not benefit from sleep in children. However, besides the absence of performance gains in children, sleep-dependent plasticity processes involved in procedural memory consolidation might be expressed through differential interference effects on the learning of novel but related procedural material. To test this hypothesis, 32 10-12-year-old children were trained on a motor rotation adaptation task. After either a sleep or a wake period, they were first retested on the same rotation applied at learning, thus assessing offline sleep-dependent changes in performance, then on the opposite (unlearned) rotation to assess sleep-dependent modulations in proactive interference coming from the consolidated visuomotor memory trace. Results show that children gradually improve performance over the learning session, showing effective adaptation to the imposed rotation. In line with previous findings, no sleep-dependent changes in performance were observed for the learned rotation. However, presentation of the opposite, unlearned deviation elicited significantly higher interference effects after post-training sleep than wakefulness in children. Considering that a definite feature of procedural motor memory and skill acquisition is the implementation of highly automatized motor behaviour, thus lacking flexibility, our results suggest a better integration and/or automation or motor adaptation skills after post-training sleep, eventually resulting in higher proactive interference effects on untrained material. PMID:24010959

  9. RNA Interference Using c-Myc-Conjugated Nanoparticles Suppresses Breast and Colorectal Cancer Models.

    PubMed

    Tangudu, Naveen K; Verma, Vinod K; Clemons, Tristan D; Beevi, Syed S; Hay, Trevor; Mahidhara, Ganesh; Raja, Meera; Nair, Rekha A; Alexander, Liza E; Patel, Anant B; Jose, Jedy; Smith, Nicole M; Zdyrko, Bogdan; Bourdoncle, Anne; Luzinov, Igor; Iyer, K Swaminathan; Clarke, Alan R; Dinesh Kumar, Lekha

    2015-05-01

    In this article, we report the development and preclinical validation of combinatorial therapy for treatment of cancers using RNA interference (RNAi). RNAi technology is an attractive approach to silence genes responsible for disease onset and progression. Currently, the critical challenge facing the clinical success of RNAi technology is in the difficulty of delivery of RNAi inducers, due to low transfection efficiency, difficulties of integration into host DNA and unstable expression. Using the macromolecule polyglycidal methacrylate (PGMA) as a platform to graft multiple polyethyleneimine (PEI) chains, we demonstrate effective delivery of small oligos (anti-miRs and mimics) and larger DNAs (encoding shRNAs) in a wide variety of cancer cell lines by successful silencing/activation of their respective target genes. Furthermore, the effectiveness of this therapy was validated for in vivo tumor suppression using two transgenic mouse models; first, tumor growth arrest and increased animal survival was seen in mice bearing Brca2/p53-mutant mammary tumors following daily intratumoral treatment with nanoparticles conjugated to c-Myc shRNA. Second, oral delivery of the conjugate to an Apc-deficient crypt progenitor colon cancer model increased animal survival and returned intestinal tissue to a non-wnt-deregulated state. This study demonstrates, through careful design of nonviral nanoparticles and appropriate selection of therapeutic gene targets, that RNAi technology can be made an affordable and amenable therapy for cancer. PMID:25695957

  10. Use of power-line interference for adaptive motion artifact removal in biopotential measurements.

    PubMed

    Xu, Lin; Rooijakkers, Michael J; Rabotti, Chiara; Peuscher, Jan; Mischi, Massimo

    2016-01-01

    Motion artifacts (MA) have long been a problem in biopotential measurements. Adaptive filtering is widely used for optimal noise removal in many biomedical applications. However, the existing adaptive filtering methods involve the use of additional sensors, limiting the applicability of adaptive filtering for MA reduction. In the present study, a novel adaptive filtering method without need for additional sensors is proposed. In biopotential measurements, movement of the electrodes and their leads may cause variations not only in the skin and half-cell potential (motion artifacts), but also in the electrode-skin impedance. Such impedance variations may also cause power-line interference modulation (PLIM), resulting in additional spectral components around the power-line interference (PLI) in the frequency domain. Demodulation of the PLI may reflect the movement-induced electrode-skin impedance variation, and can therefore represent a reference signal for the adaptive filter. Preliminary validation on ECG measurements with seven volunteers showed a high correlation coefficient (R  =  0.97) between MA and PLIM, and excellent MA removal by the proposed adaptive filter, possibly leading to improved analysis of biopotential signals. PMID:26641265

  11. Capabilities of wind tunnels with two-adaptive walls to minimize boundary interference in 3-D model testing

    NASA Technical Reports Server (NTRS)

    Rebstock, Rainer; Lee, Edwin E., Jr.

    1989-01-01

    An initial wind tunnel test was made to validate a new wall adaptation method for 3-D models in test sections with two adaptive walls. First part of the adaptation strategy is an on-line assessment of wall interference at the model position. The wall induced blockage was very small at all test conditions. Lift interference occurred at higher angles of attack with the walls set aerodynamically straight. The adaptation of the top and bottom tunnel walls is aimed at achieving a correctable flow condition. The blockage was virtually zero throughout the wing planform after the wall adjustment. The lift curve measured with the walls adapted agreed very well with interference free data for Mach 0.7, regardless of the vertical position of the wing in the test section. The 2-D wall adaptation can significantly improve the correctability of 3-D model data. Nevertheless, residual spanwise variations of wall interference are inevitable.

  12. Fabrication of two-dimensional micro patterns for adaptive optics by using laser interference lithography

    NASA Astrophysics Data System (ADS)

    Li, Xinghui; Cai, Yindi; Aihara, Ryo; Shimizu, Yuki; Ito, So; Gao, Wei

    2015-07-01

    This paper presents a fabrication method of two-dimensional micro patterns for adaptive optics with a micrometric or sub-micrometric period to be used for fabrication of micro lens array or two-dimensional diffraction gratings. A multibeam two-axis Lloyd's mirror interferometer is employed to carry out laser interference lithography for the fabrication of two-dimensional grating structures. In the proposed instrument, the optical setup consists of a light source providing a laser beam, a multi-beam generator, two plane mirrors to generate a two-dimensional XY interference pattern and a substrate on which the XY interference pattern is to be exposed. In this paper, pattern exposure tests are carried out by the developed optical configuration optimized by computer simulations. Some experimental results of the XY pattern fabrication will be reported.

  13. Virus infection suppresses Nicotiana benthamiana adaptive phenotypic plasticity.

    PubMed

    Bedhomme, Stéphanie; Elena, Santiago F

    2011-01-01

    Competition and parasitism are two important selective forces that shape life-histories, migration rates and population dynamics. Recently, it has been shown in various pathosystems that parasites can modify intraspecific competition, thus generating an indirect cost of parasitism. Here, we investigated if this phenomenon was present in a plant-potyvirus system using two viruses of different virulence (Tobacco etch virus and Turnip mosaic virus). Moreover, we asked if parasitism interacted with the shade avoidance syndrome, the plant-specific phenotypic plasticity in response to intraspecific competition. Our results indicate that the modification of intraspecific competition by parasitism is not present in the Nicotiana benthamiana--potyvirus system and suggests that this phenomenon is not universal but depends on the peculiarities of each pathosystem. However, whereas the healthy N. benthamiana presented a clear shade avoidance syndrome, this phenotypic plasticity totally disappeared when the plants were infected with TEV and TuMV, very likely resulting in a fitness loss and being another form of indirect cost of parasitism. This result suggests that the suppression or the alteration of adaptive phenotypic plasticity might be a component of virulence that is often overlooked. PMID:21359142

  14. Virus Infection Suppresses Nicotiana benthamiana Adaptive Phenotypic Plasticity

    PubMed Central

    Bedhomme, Stéphanie; Elena, Santiago F.

    2011-01-01

    Competition and parasitism are two important selective forces that shape life-histories, migration rates and population dynamics. Recently, it has been shown in various pathosystems that parasites can modify intraspecific competition, thus generating an indirect cost of parasitism. Here, we investigated if this phenomenon was present in a plant-potyvirus system using two viruses of different virulence (Tobacco etch virus and Turnip mosaic virus). Moreover, we asked if parasitism interacted with the shade avoidance syndrome, the plant-specific phenotypic plasticity in response to intraspecific competition. Our results indicate that the modification of intraspecific competition by parasitism is not present in the Nicotiana benthamiana – potyvirus system and suggests that this phenomenon is not universal but depends on the peculiarities of each pathosystem. However, whereas the healthy N. benthamiana presented a clear shade avoidance syndrome, this phenotypic plasticity totally disappeared when the plants were infected with TEV and TuMV, very likely resulting in a fitness loss and being another form of indirect cost of parasitism. This result suggests that the suppression or the alteration of adaptive phenotypic plasticity might be a component of virulence that is often overlooked. PMID:21359142

  15. Comparison of a two-dimensional adaptive-wall technique with analytical wall interference correction techniques

    NASA Technical Reports Server (NTRS)

    Mineck, Raymond E.

    1992-01-01

    A two dimensional airfoil model was tested in the adaptive wall test section of the NASA Langley 0.3 meter Transonic Cryogenic Tunnel (TCT) and in the ventilated test section of the National Aeronautical Establishment Two Dimensional High Reynold Number Facility (HRNF). The primary goal of the tests was to compare different techniques (adaptive test section walls and classical, analytical corrections) to account for wall interference. Tests were conducted over a Mach number range from 0.3 to 0.8 at chord Reynolds numbers of 10 x 10(exp 6), 15 x 10(exp 6), and 20 x 10(exp 6). The angle of attack was varied from about 12 degrees up to stall. Movement of the top and bottom test section walls was used to account for the wall interference in the HRNF tests. The test results are in good agreement.

  16. Decision Making in Concurrent Multitasking: Do People Adapt to Task Interference?

    PubMed Central

    Nijboer, Menno; Taatgen, Niels A.; Brands, Annelies; Borst, Jelmer P.; van Rijn, Hedderik

    2013-01-01

    While multitasking has received a great deal of attention from researchers, we still know little about how well people adapt their behavior to multitasking demands. In three experiments, participants were presented with a multicolumn subtraction task, which required working memory in half of the trials. This primary task had to be combined with a secondary task requiring either working memory or visual attention, resulting in different types of interference. Before each trial, participants were asked to choose which secondary task they wanted to perform concurrently with the primary task. We predicted that if people seek to maximize performance or minimize effort required to perform the dual task, they choose task combinations that minimize interference. While performance data showed that the predicted optimal task combinations indeed resulted in minimal interference between tasks, the preferential choice data showed that a third of participants did not show any adaptation, and for the remainder it took a considerable number of trials before the optimal task combinations were chosen consistently. On the basis of these results we argue that, while in principle people are able to adapt their behavior according to multitasking demands, selection of the most efficient combination of strategies is not an automatic process. PMID:24244527

  17. Reducing interferences in wireless communication systems by mobile agents with recurrent neural networks-based adaptive channel equalization

    NASA Astrophysics Data System (ADS)

    Beritelli, Francesco; Capizzi, Giacomo; Lo Sciuto, Grazia; Napoli, Christian; Tramontana, Emiliano; Woźniak, Marcin

    2015-09-01

    Solving channel equalization problem in communication systems is based on adaptive filtering algorithms. Today, Mobile Agents (MAs) with Recurrent Neural Networks (RNNs) can be also adopted for effective interference reduction in modern wireless communication systems (WCSs). In this paper MAs with RNNs are proposed as novel computing algorithms for reducing interferences in WCSs performing an adaptive channel equalization. The method to provide it is so called MAs-RNNs. We perform the implementation of this new paradigm for interferences reduction. Simulations results and evaluations demonstrates the effectiveness of this approach and as better transmission performance in wireless communication network can be achieved by using the MAs-RNNs based adaptive filtering algorithm.

  18. Adaptive wall technology for minimization of wall interferences in transonic wind tunnels

    NASA Technical Reports Server (NTRS)

    Wolf, Stephen W. D.

    1988-01-01

    Modern experimental techniques to improve free air simulations in transonic wind tunnels by use of adaptive wall technology are reviewed. Considered are the significant advantages of adaptive wall testing techniques with respect to wall interferences, Reynolds number, tunnel drive power, and flow quality. The application of these testing techniques relies on making the test section boundaries adjustable and using a rapid wall adjustment procedure. A historical overview shows how the disjointed development of these testing techniques, since 1938, is closely linked to available computer support. An overview of Adaptive Wall Test Section (AWTS) designs shows a preference for use of relatively simple designs with solid adaptive walls in 2- and 3-D testing. Operational aspects of AWTS's are discussed with regard to production type operation where adaptive wall adjustments need to be quick. Both 2- and 3-D data are presented to illustrate the quality of AWTS data over the transonic speed range. Adaptive wall technology is available for general use in 2-D testing, even in cryogenic wind tunnels. In 3-D testing, more refinement of the adaptive wall testing techniques is required before more widespread use can be planned.

  19. Study Of Adaptive-Array Signal Processing

    NASA Technical Reports Server (NTRS)

    Satorius, Edgar H.; Griffiths, Lloyd

    1990-01-01

    Report describes study of adaptive signal-processing techniques for suppression of mutual satellite interference in mobile (on ground)/satellite communication system. Presents analyses and numerical simulations of performances of two approaches to signal processing for suppression of interference. One approach, known as "adaptive side lobe canceling", second called "adaptive temporal processing".

  20. Direct calculation of wall interferences and wall adaptation for two-dimensional flow in wind tunnels with closed walls

    NASA Technical Reports Server (NTRS)

    Amecke, Juergen

    1986-01-01

    A method for the direct calculation of the wall induced interference velocity in two dimensional flow based on Cauchy's integral formula was derived. This one-step method allows the calculation of the residual corrections and the required wall adaptation for interference-free flow starting from the wall pressure distribution without any model representation. Demonstrated applications are given.

  1. Powerline interference reduction in ECG signals using empirical wavelet transform and adaptive filtering.

    PubMed

    Singh, Omkar; Sunkaria, Ramesh Kumar

    2015-01-01

    Separating an information-bearing signal from the background noise is a general problem in signal processing. In a clinical environment during acquisition of an electrocardiogram (ECG) signal, The ECG signal is corrupted by various noise sources such as powerline interference (PLI), baseline wander and muscle artifacts. This paper presents novel methods for reduction of powerline interference in ECG signals using empirical wavelet transform (EWT) and adaptive filtering. The proposed methods are compared with the empirical mode decomposition (EMD) based PLI cancellation methods. A total of six methods for PLI reduction based on EMD and EWT are analysed and their results are presented in this paper. The EWT-based de-noising methods have less computational complexity and are more efficient as compared with the EMD-based de-noising methods. PMID:25412942

  2. Adaptive suppression of subordinate reproduction in cooperative mammals.

    PubMed

    Clutton-Brock, Tim H; Hodge, Sarah J; Flower, Tom P; Spong, Goran F; Young, Andrew J

    2010-11-01

    Attempts to account for observed variation in the degree of reproductive skew among cooperative breeders have usually assumed that subordinate breeding has fitness costs to dominant females. They argue that dominant females concede reproductive opportunities to subordinates to retain them in the group or to dissuade them from challenging for the dominant position or that subordinate females breed where dominants are incapable of controlling them. However, an alternative possibility is that suppressing subordinate reproduction has substantive costs to the fitness of dominant females and that variation in these costs generates differences in the net benefits of suppression to dominants which are responsible for variation in the frequency of subordinate breeding that is not a consequence of either reproductive concessions or limitations in dominant control. Here, we show that, in wild Kalahari meerkats (Suricata suricatta), the frequency with which dominants evict subordinates or kill their pups varies with the costs and benefits to dominants of suppressing subordinate breeding, including the dominants' reproductive status, the size of their group, and the relatedness of subordinates. We review evidence from other studies that the suppression of reproduction by subordinates varies with the likely costs of subordinate breeding to dominants. PMID:20846043

  3. Effects of surround suppression on response adaptation of V1 neurons to visual stimuli

    PubMed Central

    LI, Peng; JIN, Cai-Hong; JIANG, San; LI, Miao-Miao; WANG, Zi-Lu; ZHU, Hui; CHEN, Cui-Yun; HUA, Tian-Miao

    2014-01-01

    The influence of intracortical inhibition on the response adaptation of visual cortical neurons remains in debate. To clarify this issue, in the present study the influence of surround suppression evoked through the local inhibitory interneurons on the adaptation effects of neurons in the primary visual cortex (V1) were observed. Moreover, the adaptations of V1 neurons to both the high-contrast visual stimuli presented in the classical receptive field (CRF) and to the costimulation presented in the CRF and the surrounding nonclassical receptive field (nCRF) were compared. The intensities of surround suppression were modulated with different sized grating stimuli. The results showed that the response adaptation of V1 neurons decreased significantly with the increase of surround suppression and this adaptation decrease was due to the reduction of the initial response of V1 neurons to visual stimuli. However, the plateau response during adaptation showed no significant changes. These findings indicate that the adaptation effects of V1 neurons may not be directly affected by surround suppression, but may be dynamically regulated by a negative feedback network and be finely adjusted by its initial spiking response to stimulus. This adaptive regulation is not only energy efficient for the central nervous system, but also beneficially acts to maintain the homeostasis of neuronal response to long-presenting visual signals. PMID:25297081

  4. Dispersion-flattened-fiber based optical thresholder for multiple-access-interference suppression in OCDMA system.

    PubMed

    Wang, Xu; Hamanaka, Taro; Wada, Naoya; Kitayama, Ken-Ichi

    2005-07-11

    An optical thresholding technique based on super-continuum generation in dispersion flattened fiber is proposed and experimentally demonstrated to enable data-rate detection in optical code division multiple access networks. The proposed scheme exhibits an excellent discrimination between a desired signal and interference signals with features of pulse reshaping, low insertion loss, polarization independency as well as reasonable operation power. PMID:19498545

  5. Investigation of RNA interference suppression of matrix metalloproteinase-9 in mouse model of atherosclerosis

    PubMed Central

    Jin, Zhe-Xiu; Xiong, Qiang; Jia, Fang; Sun, Chun-Ling; Zhu, Hong-Tao; Ke, Fu-Sheng

    2015-01-01

    Objective: To investigate the effect of RNA interference of matrix metalloproteinase (MMP)-9 on atherosclerosis on atherosclerosis in apolipoprotein E (ApoE)-/- mouse. Methods: ApoE-/- mouse strain and three cell lines (293T, NIH3T3 and Raw264.7) were used in the present study to investigate the effect of MMP-9 silencing by RNA interference. Thirty 10-week-old ApoE-/- mice were randomly assigned to a control group, lentiviruses with naked vector group and Lentiviruses-MMP-9 intervention group (n = 10). Aortic atherosclerotic plaques of the mice were stained with immunohistochemical techniques, the MMP-9 and high-sensitivity C-reactive protein levels of three groups were detected simultaneously. Expression of MMP-9 was significantly down-regulated in interference group. MMP-9 and high-sensitivity C-reactive protein levels in MMP-9 interference group were significantly lower than that of the control group. Conclusion: The expression of MMP-9 is closely related to vulnerability of atherosclerotic plaques. Silencing of MMP-9 expression acts as a positive role in maintenance of atherosclerotic plaque stability. The present study provides novel experimental insight for the treatment of vulnerable plaques in atherosclerosis. PMID:26131101

  6. Recovering fNIRS brain signals: physiological interference suppression with independent component analysis

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Shi, M.; Sun, J.; Yang, C.; Zhang, Yajuan; Scopesi, F.; Makobore, P.; Chin, C.; Serra, G.; Wickramasinghe, Y. A. B. D.; Rolfe, P.

    2015-02-01

    Brain activity can be monitored non-invasively by functional near-infrared spectroscopy (fNIRS), which has several advantages in comparison with other methods, such as flexibility, portability, low cost and fewer physical restrictions. However, in practice fNIRS measurements are often contaminated by physiological interference arising from cardiac contraction, breathing and blood pressure fluctuations, thereby severely limiting the utility of the method. Hence, further improvement is necessary to reduce or eliminate such interference in order that the evoked brain activity information can be extracted reliably from fNIRS data. In the present paper, the multi-distance fNIRS probe configuration has been adopted. The short-distance fNIRS measurement is treated as the virtual channel and the long-distance fNIRS measurement is treated as the measurement channel. Independent component analysis (ICA) is employed for the fNIRS recordings to separate the brain signals and the interference. Least-absolute deviation (LAD) estimator is employed to recover the brain activity signals. We also utilized Monte Carlo simulations based on a five-layer model of the adult human head to evaluate our methodology. The results demonstrate that the ICA algorithm has the potential to separate physiological interference in fNIRS data and the LAD estimator could be a useful criterion to recover the brain activity signals.

  7. Adaptive top-down suppression of hippocampal activity and the purging of intrusive memories from consciousness.

    PubMed

    Benoit, Roland G; Hulbert, Justin C; Huddleston, Ean; Anderson, Michael C

    2015-01-01

    When reminded of unwanted memories, people often attempt to suppress these experiences from awareness. Prior work indicates that control processes mediated by the dorsolateral prefrontal cortex (DLPFC) modulate hippocampal activity during such retrieval suppression. It remains unknown whether this modulation plays a role in purging an intrusive memory from consciousness. Here, we combined fMRI and effective connectivity analyses with phenomenological reports to scrutinize a role for adaptive top-down suppression of hippocampal retrieval processes in terminating mnemonic awareness of intrusive memories. Participants either suppressed or recalled memories of pictures depicting faces or places. After each trial, they reported their success at regulating awareness of the memory. DLPFC activation was greatest when unwanted memories intruded into consciousness and needed to be purged, and this increased engagement predicted superior control of intrusive memories over time. However, hippocampal activity was decreased during the suppression of place memories only. Importantly, the inhibitory influence of the DLPFC on the hippocampus was linked to the ensuing reduction in intrusions of the suppressed memories. Individuals who exhibited negative top-down coupling during early suppression attempts experienced fewer involuntary memory intrusions later on. Over repeated suppressions, the DLPFC-hippocampus connectivity grew less negative with the degree that they no longer had to purge unwanted memories from awareness. These findings support a role of DLPFC in countermanding the unfolding recollection of an unwanted memory via the suppression of hippocampal processing, a mechanism that may contribute to adaptation in the aftermath of traumatic experiences. PMID:25100219

  8. Hypercapnia Suppresses the HIF-dependent Adaptive Response to Hypoxia.

    PubMed

    Selfridge, Andrew C; Cavadas, Miguel A S; Scholz, Carsten C; Campbell, Eric L; Welch, Lynn C; Lecuona, Emilia; Colgan, Sean P; Barrett, Kim E; Sporn, Peter H S; Sznajder, Jacob I; Cummins, Eoin P; Taylor, Cormac T

    2016-05-27

    Molecular oxygen and carbon dioxide are the primary gaseous substrate and product of oxidative metabolism, respectively. Hypoxia (low oxygen) and hypercapnia (high carbon dioxide) are co-incidental features of the tissue microenvironment in a range of pathophysiologic states, including acute and chronic respiratory diseases. The hypoxia-inducible factor (HIF) is the master regulator of the transcriptional response to hypoxia; however, little is known about the impact of hypercapnia on gene transcription. Because of the relationship between hypoxia and hypercapnia, we investigated the effect of hypercapnia on the HIF pathway. Hypercapnia suppressed HIF-α protein stability and HIF target gene expression both in mice and cultured cells in a manner that was at least in part independent of the canonical O2-dependent HIF degradation pathway. The suppressive effects of hypercapnia on HIF-α protein stability could be mimicked by reducing intracellular pH at a constant level of partial pressure of CO2 Bafilomycin A1, a specific inhibitor of vacuolar-type H(+)-ATPase that blocks lysosomal degradation, prevented the hypercapnic suppression of HIF-α protein. Based on these results, we hypothesize that hypercapnia counter-regulates activation of the HIF pathway by reducing intracellular pH and promoting lysosomal degradation of HIF-α subunits. Therefore, hypercapnia may play a key role in the pathophysiology of diseases where HIF is implicated. PMID:27044749

  9. Suppression and enhancement of distortion-product otoacoustic emissions by interference tones above f(2). I. Basic findings in rabbits.

    PubMed

    Martin, G K; Stagner, B B; Jassir, D; Telischi, F F; Lonsbury-Martin, B L

    1999-10-01

    The present study measured interference-response areas (IRAs) for distortion-product otoacoustic emissions (DPOAEs) at 2f(1)-f(2), 3f(1)-2f(2), and 2f(2)-f(1). The IRAs were obtained in either awake or anesthetized rabbits, or in anesthetized guinea pigs and mice, by sweeping the frequencies and levels of an interference tone (IT) around a set of f(1) and f(2) primary tones, at several fixed frequencies and levels, while plotting the effects of the IT on DPOAE level. An unexpected outcome was the occurrence of regions of suppression and/or enhancement of DPOAE level when the IT was at a frequency slightly less than to more than an octave above f(2). The IRA of the 2f(1)-f(2) DPOAE typically displayed a high-frequency (HF) lobe of suppression, while the 2f(2)-f(1) emission often exhibited considerable amounts of enhancement. Moreover, for the 2f(2)-f(1) DPOAE, when enhancement was absent, its IRA usually tuned to a region above f(2). Whether or not suppression/enhancement was observed depended upon primary-tone level and frequency separation, as well as on the relative levels of the two primaries. Various physiological manipulations involving anesthesia, eighth-nerve section, diuretic administration, or pure-tone overstimulation showed that these phenomena were of cochlear origin, and were not dependent upon the acoustic reflex or cochlear-efferent activity. The aftereffects of applying diuretics or over-exposures revealed that suppression/enhancement required the presence of sensitive, low-level DPOAE-generator sources. Additionally, suppression/enhancement were general effects in that, in addition to rabbits, they were also observed in mice and guinea pigs. Further, corresponding plots of DPOAE phase often revealed areas of differing phase change in the vicinity of the primary tones as compared to regions above f(2). These findings, along with the effects of tonal exposures designed to fatigue regions above f(2), and instances in which DPOAE level was dependent

  10. Reversible suppression of an essential gene in adult mice using transgenic RNA interference

    PubMed Central

    McJunkin, Katherine; Mazurek, Anthony; Premsrirut, Prem K.; Zuber, Johannes; Dow, Lukas E.; Simon, Janelle; Stillman, Bruce; Lowe, Scott W.

    2011-01-01

    RNAi has revolutionized loss-of-function genetics by enabling sequence-specific suppression of virtually any gene. Furthermore, tetracycline response elements (TRE) can drive expression of short hairpin RNAs (shRNAs) for inducible and reversible target gene suppression. Here, we demonstrate the feasibility of transgenic inducible RNAi for suppression of essential genes. We set out to directly target cell proliferation by screening an RNAi library against DNA replication factors and identified multiple shRNAs against Replication Protein A, subunit 3 (RPA3). We generated transgenic mice with TRE-driven Rpa3 shRNAs whose expression enforced a reversible cell cycle arrest. In adult mice, the block in cell proliferation caused rapid atrophy of the intestinal epithelium which led to weight loss and lethality within 8–11 d of shRNA induction. Upon shRNA withdrawal, villus atrophy and weight loss were fully reversible. Thus, shRpa3 transgenic mice provide an interesting tool to study tissue maintenance and regeneration. Overall, we have established a robust system that serves the purpose of temperature-sensitive alleles in other model organisms, enabling inducible and reversible suppression of essential genes in a mammalian system. PMID:21482754

  11. A Re-Examination of Global Suppression of RNA Interference by HIV-1

    PubMed Central

    Sanghvi, Viraj R.; Steel, Laura F.

    2011-01-01

    The nature of the interaction between replicating HIV-1 and the cellular RNAi pathway has been controversial, but it is clear that it can be complex and multifaceted. It has been proposed that the interaction is bi-directional, whereby cellular silencing pathways can restrict HIV-1 replication, and in turn, HIV-1 can suppress silencing pathways. Overall suppression of RNAi has been suggested to occur via direct binding and inhibition of Dicer by the HIV-1 Tat protein or through sequestration of TRBP, a Dicer co-factor, by the structured TAR element of HIV-1 transcripts. The role of Tat as an inhibitor of Dicer has been questioned and our results support and extend the conclusion that Tat does not inhibit RNAi that is mediated by either exogenous or endogenous miRNAs. Similarly, we find no suppression of silencing pathways in cells with replicating virus, suggesting that viral products such as the TAR RNA elements also do not reduce the efficacy of cellular RNA silencing. However, knockdown of Dicer does allow increased viral replication and this occurs at a post-transcriptional level. These results support the idea that although individual miRNAs can act to restrict HIV-1 replication, the virus does not counter these effects through a global suppression of RNAi synthesis or processing. PMID:21386885

  12. Adaptive Radar Detection of a Subspace Signal Embedded in Subspace Structured Plus Gaussian Interference Via Invariance

    NASA Astrophysics Data System (ADS)

    De Maio, Antonio; Orlando, Danilo

    2016-04-01

    This paper deals with adaptive radar detection of a subspace signal competing with two sources of interference. The former is Gaussian with unknown covariance matrix and accounts for the joint presence of clutter plus thermal noise. The latter is structured as a subspace signal and models coherent pulsed jammers impinging on the radar antenna. The problem is solved via the Principle of Invariance which is based on the identification of a suitable group of transformations leaving the considered hypothesis testing problem invariant. A maximal invariant statistic, which completely characterizes the class of invariant decision rules and significantly compresses the original data domain, as well as its statistical characterization are determined. Thus, the existence of the optimum invariant detector is addressed together with the design of practically implementable invariant decision rules. At the analysis stage, the performance of some receivers belonging to the new invariant class is established through the use of analytic expressions.

  13. Adaptive Detection of Point-Like Targets in Spectrally Symmetric Interference

    NASA Astrophysics Data System (ADS)

    De Maio, Antonio; Orlando, Danilo; Hao, Chengpeng; Foglia, Goffredo

    2016-06-01

    We address adaptive radar detection of targets embedded in ground clutter dominated environments characterized by a symmetrically structured power spectral density. At the design stage, we leverage on the spectrum symmetry for the interference to come up with decision schemes capable of capitalizing the a-priori information on the covariance structure. To this end, we prove that the detection problem at hand can be formulated in terms of real variables and, then, we apply design procedures relying on the GLRT, the Rao test, and the Wald test. Specifically, the estimates of the unknown parameters under the target presence hypothesis are obtained through an iterative optimization algorithm whose convergence and quality guarantee is thoroughly proved. The performance analysis, both on simulated and on real radar data, confirms the superiority of the considered architectures over their conventional counterparts which do not take advantage of the clutter spectral symmetry.

  14. High-speed analog fiber-optic link for electromagnetic interference suppression in infrared power measurement

    NASA Astrophysics Data System (ADS)

    Liu, Fei; Strauch, Stefanie; Horton, Robert; Evans, Russell; Hwang, David

    2011-08-01

    Electromagnetic interference (EMI) is a common problem in a high-power pulsed infrared laser measurement. In order to eliminate susceptibility to radiated EMI, we developed, tested and implemented an infrared power measurement system using a high-speed analog fiber-optic link. Key components are commercially available parts designed for high-speed digital data transmission, but can be operated in analog mode. We successfully utilized the system for time-resolved measurements of high-power transversely-excited atmospheric-pressure CO2 lasers in amplifier and oscillator configurations. This paper presents experimental setup, testing results, and the details of the laser power measurements results.

  15. Channel estimation algorithm for interference suppression in IMDD-OQAM-OFDM transmission systems

    NASA Astrophysics Data System (ADS)

    Zhang, Lu; Xiao, Shilin; Bi, Meihua; Liu, Ling; Zhou, Zhao

    2016-04-01

    In this paper, we investigate the intrinsic interference caused by intra-symbol data and channel noise in the intensity-modulation direct-detection OQAM-OFDM (IMDD-OQAM-OFDM) system by theoretical derivation. Based on the analysis, we proposed and experimentally demonstrated a channel estimation algorithm with the combination of IAM-C and frequency-averaging method to combat the effect of these noises. Experimental results show that compared to the common channel estimation algorithms, our algorithm can greatly reduce the error vector magnitude (EVM) and achieve ~1.5 dB sensitivity improvement.

  16. Autophagy suppresses host adaptive immune responses toward Borrelia burgdorferi.

    PubMed

    Buffen, Kathrin; Oosting, Marije; Li, Yang; Kanneganti, Thirumala-Devi; Netea, Mihai G; Joosten, Leo A B

    2016-09-01

    We have previously demonstrated that inhibition of autophagy increased the Borrelia burgdorferi induced innate cytokine production in vitro, but little is known regarding the effect of autophagy on in vivo models of Borrelia infection. Here, we showed that ATG7-deficient mice that were intra-articular injected with Borrelia spirochetes displayed increased joint swelling, cell influx, and enhanced interleukin-1β and interleukin-6 production by inflamed synovial tissue. Because both interleukin-1β and interleukin-6 are linked to the development of adaptive immune responses, we examine the function of autophagy on Borrelia induced adaptive immunity. Human peripheral blood mononuclear cells treated with autophagy inhibitors showed an increase in interleukin-17, interleukin-22, and interferon-γ production in response to exposure to Borrelia burgdorferi. Increased IL-17 production was dependent on IL-1β release but, interestingly, not on interleukin-23 production. In addition, cytokine quantitative trait loci in ATG9B modulate the Borrelia induced interleukin-17 production. Because high levels of IL-17 have been found in patients with confirmed, severe, chronic borreliosis, we propose that the modulation of autophagy may be a potential target for anti-inflammatory therapy in patients with persistent Lyme disease. PMID:27101991

  17. Adaptive threshold harvesting and the suppression of transients.

    PubMed

    Segura, Juan; Hilker, Frank M; Franco, Daniel

    2016-04-21

    Fluctuations in population size are in many cases undesirable, as they can induce outbreaks and extinctions or impede the optimal management of populations. We propose the strategy of adaptive threshold harvesting (ATH) to control fluctuations in population size. In this strategy, the population is harvested whenever population size has grown beyond a certain proportion in comparison to the previous generation. Taking such population increases into account, ATH intervenes also at smaller population sizes than the strategy of threshold harvesting. Moreover, ATH is the harvesting version of adaptive limiter control (ALC) that has recently been shown to stabilize population oscillations in both experiments and theoretical studies. We find that ATH has similar stabilization properties as ALC and thus offers itself as a harvesting alternative for the control of pests, exploitation of biological resources, or when restocking interventions required from ALC are unfeasible. We present numerical simulations of ATH to illustrate its performance in the presence of noise, lattice effect, and Allee effect. In addition, we propose an adjustment to both ATH and ALC that restricts interventions when control seems unnecessary, i.e. when population size is too small or too large, respectively. This adjustment cancels prolonged transients. PMID:26854876

  18. Adaptive noise suppression for a dual-microphone hearing aid.

    PubMed

    Wouters, Jan; Berghe, Jeff Vanden; Maj, Jean-Baptiste

    2002-10-01

    An adaptive beamformer for behind-the-ear dual-microphone hearing aids has been optimized for speech intelligibility enhancement in the presence of disturbing sounds or noise. The noise reduction approach is based on the scheme presented by Vanden Berghe and Wouters (1998). A real-time implementation of the signal processing is realized in Audallion, a wearable, small digital signal processing (DSP) platform. After physical evaluation, speech-in-noise intelligibility tests have been carried out on three normally-hearing and two hearing-impaired subjects. A significant speech reception threshold improvement of 11.3 dB was obtained in a moderately reverberant environment for one jammer sound source (steady speech-weighted noise or multi-talker babble) in a direction of 90 degrees relative to the direction of the speech. PMID:12403608

  19. Reversible Suppression of Cyclooxygenase 2 (COX-2) Expression In Vivo by Inducible RNA Interference

    PubMed Central

    Zaiss, Anne K.; Zuber, Johannes; Chu, Chun; Machado, Hidevaldo B.; Jiao, Jing; Catapang, Arthur B.; Ishikawa, Tomo-o; Gil, Jose S.; Lowe, Scott W.; Herschman, Harvey R.

    2014-01-01

    Prostaglandin-endoperoxide synthase 2 (PTGS2), also known as cyclooxygenase 2 (COX-2), plays a critical role in many normal physiological functions and modulates a variety of pathological conditions. The ability to turn endogenous COX-2 on and off in a reversible fashion, at specific times and in specific cell types, would be a powerful tool in determining its role in many contexts. To achieve this goal, we took advantage of a recently developed RNA interference system in mice. An shRNA targeting the Cox2 mRNA 3′untranslated region was inserted into a microRNA expression cassette, under the control of a tetracycline response element (TRE) promoter. Transgenic mice containing the COX-2-shRNA were crossed with mice encoding a CAG promoter-driven reverse tetracycline transactivator, which activates the TRE promoter in the presence of tetracycline/doxycycline. To facilitate testing the system, we generated a knockin reporter mouse in which the firefly luciferase gene replaces the Cox2 coding region. Cox2 promoter activation in cultured cells from triple transgenic mice containing the luciferase allele, the shRNA and the transactivator transgene resulted in robust luciferase and COX-2 expression that was reversibly down-regulated by doxycycline administration. In vivo, using a skin inflammation-model, both luciferase and COX-2 expression were inhibited over 80% in mice that received doxycycline in their diet, leading to a significant reduction of infiltrating leukocytes. In summary, using inducible RNA interference to target COX-2 expression, we demonstrate potent, reversible Cox2 gene silencing in vivo. This system should provide a valuable tool to analyze cell type-specific roles for COX-2. PMID:24988319

  20. Adaptive control and noise suppression by a variable-gain gradient algorithm

    NASA Technical Reports Server (NTRS)

    Merhav, S. J.; Mehta, R. S.

    1987-01-01

    An adaptive control system based on normalized LMS filters is investigated. The finite impulse response of the nonparametric controller is adaptively estimated using a given reference model. Specifically, the following issues are addressed: The stability of the closed loop system is analyzed and heuristically established. Next, the adaptation process is studied for piecewise constant plant parameters. It is shown that by introducing a variable-gain in the gradient algorithm, a substantial reduction in the LMS adaptation rate can be achieved. Finally, process noise at the plant output generally causes a biased estimate of the controller. By introducing a noise suppression scheme, this bias can be substantially reduced and the response of the adapted system becomes very close to that of the reference model. Extensive computer simulations validate these and demonstrate assertions that the system can rapidly adapt to random jumps in plant parameters.

  1. High precision Pu isotope ratios using MC-ICPMS equipped with collision-cell technology to suppress U isobaric interferences

    NASA Astrophysics Data System (ADS)

    Granet, M.; Isnard, H.; Nonell, A.; Quidelleur, S.; Chartier, F.

    2009-04-01

    The measurement of Pu isotope ratios is of prime interest in both the environmental and nuclear research fields. First, new chronometric tracers need to be developed in order to understand and quantify the mechanisms and time-scales controlling the landscape evolution since it gives informations on climatic variations. Additionally, the analysis of Pu isotopes after irradiation of 235U is required in the transmutation field in order to determine basic neutronic data such as cross sections and reaction rates. High precision isotope ratios measurements are usually performed with sector field mass spectrometers, either by Thermal Ionization Mass Spectrometry (TIMS) or by Multiple Collection Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS). One of the major drawbacks in analysing Pu isotopes is the occurrence of U isobaric interferences: 238U-238Pu and 238UH+-239Pu. Here we propose to suppress these interferences by adding reactive gases in the collision-reaction cell of the MC-ICP-MS (Isoprobe, GV Instruments, Manchester, UK). The difference of reactivity for U and Pu towards these gases allows the measurement of Pu isotopes with precision and accuracy similar to those obtained after a previous chemical separation of Pu from U using anion-exchange resin. This study thus confirms that collision-reaction cells are powerful tools to perform isotopic measurements of soils, river sediments or irradiated materials without former systematic chemical separations as U interferences are completely removed in situ. References Granet et al. (2008), Spectrochimica Acta Part B 63, 1309-1314. Moureau et al. (2008), JAAS 23, 1538-1544.

  2. An Adaptive Instability Suppression Controls Method for Aircraft Gas Turbine Engine Combustors

    NASA Technical Reports Server (NTRS)

    Kopasakis, George; DeLaat, John C.; Chang, Clarence T.

    2008-01-01

    An adaptive controls method for instability suppression in gas turbine engine combustors has been developed and successfully tested with a realistic aircraft engine combustor rig. This testing was part of a program that demonstrated, for the first time, successful active combustor instability control in an aircraft gas turbine engine-like environment. The controls method is called Adaptive Sliding Phasor Averaged Control. Testing of the control method has been conducted in an experimental rig with different configurations designed to simulate combustors with instabilities of about 530 and 315 Hz. Results demonstrate the effectiveness of this method in suppressing combustor instabilities. In addition, a dramatic improvement in suppression of the instability was achieved by focusing control on the second harmonic of the instability. This is believed to be due to a phenomena discovered and reported earlier, the so called Intra-Harmonic Coupling. These results may have implications for future research in combustor instability control.

  3. Multi-Bit Nano-Electromechanical Nonvolatile Memory Cells (Zigzag T Cells) for the Suppression of Bit-to-Bit Interference.

    PubMed

    Choi, Woo Young; Han, Jae Hwan; Cha, Tae Min

    2016-05-01

    Multi-bit nano-electromechanical (NEM) nonvolatile memory cells such as T cells were proposed for higher memory density. However, they suffered from bit-to-bit interference (BI). In order to suppress BI without sacrificing cell size, this paper proposes zigzag T cell structures. The BI suppression of the proposed zigzag T cell is verified by finite-element modeling (FEM). Based on the FEM results, the design of zigzag T cells is optimized. PMID:27483893

  4. Geminivirus Rep protein interferes with the plant DNA methylation machinery and suppresses transcriptional gene silencing.

    PubMed

    Rodríguez-Negrete, Edgar; Lozano-Durán, Rosa; Piedra-Aguilera, Alvaro; Cruzado, Lucia; Bejarano, Eduardo R; Castillo, Araceli G

    2013-07-01

    Cytosine methylation is an epigenetic mark that promotes gene silencing and plays an important role in genome defence against transposons and invading DNA viruses. Previous data showed that the largest family of single-stranded DNA viruses, Geminiviridae, prevents methylation-mediated transcriptional gene silencing (TGS) by interfering with the proper functioning of the plant methylation cycle. Here, we describe a novel counter-defence strategy used by geminiviruses, which reduces the expression of the plant maintenance DNA methyltransferases, METHYLTRANSFERASE 1 (MET1) and CHROMOMETHYLASE 3 (CMT3), in both locally and systemically infected tissues. We demonstrated that the virus-mediated repression of these two maintenance DNA methyltransferases is widespread among geminivirus species. Additionally, we identified Rep (Replication associated protein) as the geminiviral protein responsible for the repression of MET1 and CMT3, and another viral protein, C4, as an ancillary player in MET1 down-regulation. The presence of Rep suppressed TGS of an Arabidopsis thaliana transgene and of host loci whose expression was strongly controlled by CG methylation. Bisulfite sequencing analyses showed that the expression of Rep caused a substantial reduction in the levels of DNA methylation at CG sites. Our findings suggest that Rep, the only viral protein essential for replication, displays TGS suppressor activity through a mechanism distinct from that thus far described for geminiviruses. PMID:23614786

  5. Powdery mildew suppresses herbivore-induced plant volatiles and interferes with parasitoid attraction in Brassica rapa.

    PubMed

    Desurmont, Gaylord A; Xu, Hao; Turlings, Ted C J

    2016-09-01

    The co-occurrence of different antagonists on a plant can greatly affect infochemicals with ecological consequences for higher trophic levels. Here we investigated how the presence of a plant pathogen, the powdery mildew Erysiphe cruciferarum, on Brassica rapa affects (1) plant volatiles emitted in response to damage by a specialist herbivore, Pieris brassicae; (2) the attraction of the parasitic wasp Cotesia glomerata and (3) the performance of P. brassicae and C. glomerata. Plant volatiles were significantly induced by herbivory in both healthy and mildew-infected plants, but were quantitatively 41% lower for mildew-infected plants compared to healthy plants. Parasitoids strongly preferred Pieris-infested plants to dually-infested (Pieris + mildew) plants, and preferred dually infested plants over only mildew-infected plants. The performance of P. brassicae was unaffected by powdery mildew, but C. glomerata cocoon mass was reduced when parasitized caterpillars developed on mildew-infected plants. Thus, avoidance of mildew-infested plants may be adaptive for C. glomerata parasitoids, whereas P. brassicae caterpillars may suffer less parasitism on mildew-infected plants in nature. From a pest management standpoint, the concurrent presence of multiple plant antagonists can affect the efficiency of specific natural enemies, which may in turn have a negative impact on the regulation of pest populations. PMID:27043839

  6. Calcineurin inhibitor tacrolimus does not interfere with the suppression of hepatitis C virus infection by interferon-alpha.

    PubMed

    Pan, Qiuwei; Metselaar, Herold J; de Ruiter, Petra; Kwekkeboom, Jaap; Tilanus, Hugo W; Janssen, Harry L A; van der Laan, Luc J W

    2010-04-01

    Immunosuppression considerably affects hepatitis C virus (HCV) recurrence and the outcome of antiviral treatment after liver transplantation. Recent findings have suggested that the calcineurin inhibitor tacrolimus (Tac), unlike cyclosporine A (CsA), interferes with the antiviral activity of interferon-alpha (IFN-alpha) in vitro. The aim of this study was to more extensively investigate the effects of calcineurin inhibitors on IFN-alpha signaling and antiviral activity in subgenomic and infectious HCV models. Treatment with Tac and CsA did not affect Huh7 cell proliferation at doses of 10 to 500 ng/mL; however, it completely inhibited T cell proliferation. In contrast to previous reports, Tac had no effect on IFN-alpha-stimulated reporter gene expression, even at the dose of 5 microg/mL. Furthermore, in Huh7 subgenomic HCV replicon cells, treatment with Tac had no significant effect on the suppression of viral replication by IFN-alpha. In the infectious HCV model, treatment with IFN-alpha effectively inhibited both viral RNA replication and de novo production of virus particles, and neither was attenuated at any concentration of Tac. CsA had no significant effect on IFN-alpha-stimulated reporter gene expression; however, as shown previously, a combination of CsA (at 500 ng/mL and higher) and IFN-alpha resulted in enhanced inhibition of viral replication in both the subgenomic and infectious HCV models. In conclusion, our study shows no evidence that Tac or CsA interferes with IFN-alpha-mediated inhibition of HCV replication and virion production in vitro. Therefore, no further mechanistic arguments have been found to break the clinical controversy about the choice of calcineurin inhibitors during posttransplantation antiviral therapy. PMID:20373462

  7. Brugia malayi Microfilariae Induce a Regulatory Monocyte/Macrophage Phenotype That Suppresses Innate and Adaptive Immune Responses

    PubMed Central

    Venugopal, Gopinath; Rao, Gopala B.; Lucius, Richard; Srikantam, Aparna; Hartmann, Susanne

    2014-01-01

    Background Monocytes and macrophages contribute to the dysfunction of immune responses in human filariasis. During patent infection monocytes encounter microfilariae in the blood, an event that occurs in asymptomatically infected filariasis patients that are immunologically hyporeactive. Aim To determine whether blood microfilariae directly act on blood monocytes and in vitro generated macrophages to induce a regulatory phenotype that interferes with innate and adaptive responses. Methodology and principal findings Monocytes and in vitro generated macrophages from filaria non-endemic normal donors were stimulated in vitro with Brugia malayi microfilarial (Mf) lysate. We could show that monocytes stimulated with Mf lysate develop a defined regulatory phenotype, characterised by expression of the immunoregulatory markers IL-10 and PD-L1. Significantly, this regulatory phenotype was recapitulated in monocytes from Wuchereria bancrofti asymptomatically infected patients but not patients with pathology or endemic normals. Monocytes from non-endemic donors stimulated with Mf lysate directly inhibited CD4+ T cell proliferation and cytokine production (IFN-γ, IL-13 and IL-10). IFN-γ responses were restored by neutralising IL-10 or PD-1. Furthermore, macrophages stimulated with Mf lysate expressed high levels of IL-10 and had suppressed phagocytic abilities. Finally Mf lysate applied during the differentiation of macrophages in vitro interfered with macrophage abilities to respond to subsequent LPS stimulation in a selective manner. Conclusions and significance Conclusively, our study demonstrates that Mf lysate stimulation of monocytes from healthy donors in vitro induces a regulatory phenotype, characterized by expression of PD-L1 and IL-10. This phenotype is directly reflected in monocytes from filarial patients with asymptomatic infection but not patients with pathology or endemic normals. We suggest that suppression of T cell functions typically seen in lymphatic

  8. RNA interference against MDM2 suppresses tumor growth and metastasis in pancreatic carcinoma SW1990HM cells.

    PubMed

    Shi, Weidong; Meng, Zhiqiang; Chen, Zhen; Hua, Yongqiang; Gao, Huifeng; Wang, Peng; Lin, Junhua; Zhou, Zhenhua; Luo, Jianmin; Liu, Luming

    2014-02-01

    In our previous study, the mouse double minute 2 (MDM2) was identified as one of the leading genes that promote the metastasis of pancreatic cancer (PC). However, the mechanism by which MDM2 promotes metastasis of PC is not understood. In this study, we show that down-regulation of MDM2 through lentivirus-mediated RNA interference could also suppress in vitro proliferation and in vivo tumor growth, and led to an obvious inhibition of both in vitro invasion and in vivo live metastases of SW1990HM cells which had an over-expression of MDM2 and a higher metastatic potential. Moreover, we also show that the down-regulation of MDM2 induced a significant decrease in MMP9, Ki-67 and increase in P53, E-Cadherin expression, and results in an altered expression of genes involved in metastasis, apoptosis, and cell proliferation. Our results suggest that MDM2 plays an important role in metastasis as well as tumor growth of PC. MDM2 could be a hopeful target for the control of PC. PMID:22200978

  9. Robust vibration suppression of an adaptive circular composite plate for satellite thrust vector control

    NASA Astrophysics Data System (ADS)

    Yan, Su; Ma, Kougen; Ghasemi-Nejhad, Mehrdad N.

    2008-03-01

    In this paper, a novel application of adaptive composite structures, a University of Hawaii at Manoa (UHM) smart composite platform, is developed for the Thrust Vector Control (TVC) of satellites. The device top plate of the UHM platform is an adaptive circular composite plate (ACCP) that utilizes integrated sensors/actuators and controllers to suppress low frequency vibrations during the thruster firing as well as to potentially isolate dynamic responses from the satellite structure bus. Since the disturbance due to the satellite thruster firing can be estimated, a combined strategy of an adaptive disturbance observer (DOB) and feed-forward control is proposed for vibration suppression of the ACCP with multi-sensors and multi-actuators. Meanwhile, the effects of the DOB cut-off frequency and the relative degree of the low-pass filter on the DOB performance are investigated. Simulations and experimental results show that higher relative degree of the low-pass filter with the required cut-off frequency will enhance the DOB performance for a high-order system control. Further, although the increase of the filter cut-off frequency can guarantee a sufficient stability margin, it may cause an undesirable increase of the control bandwidth. The effectiveness of the proposed adaptive DOB with feed-forward control strategy is verified through simulations and experiments using the ACCP system.

  10. Adaptive PI control strategy for flat permanent magnet linear synchronous motor vibration suppression

    NASA Astrophysics Data System (ADS)

    Meng, Fanwei; Liu, Chengying; Li, Zhijun; Wang, Liping

    2013-01-01

    Due to low damping ratio, flat permanent magnet linear synchronous motor's vibration is difficult to be damped and the accuracy is limited. The vibration suppressing results are not good enough in the existing research because only the longitudinal direction vibration is considered while the normal direction vibration is neglected. The parameters of the direct-axis current controller are set to be the same as those of the quadrature-axis current controller commonly. This causes contradiction between signal noise and response. To suppress the vibration, the electromagnetic force model of the flat permanent magnet synchronous linear motor is formulated first. Through the analysis of the effect that direct-axis current noise and quadrature-axis current noise have on both direction vibration, it can be declared that the conclusion that longitudinal direction vibration is only related to the quadrature-axis current noise while the normal direction vibration is related to both the quadrature-axis current noise and direct-axis current noise. Then, the simulation test on current loop with a low-pass filter is conducted and the results show that the low-pass filter can not suppress the vibration but makes the vibration more severe. So a vibration suppressing strategy that the proportional gain of direct-axis current controller adapted according to quadrature-axis reference current is proposed. This control strategy can suppress motor vibration by suppressing direct-axis current noise. The experiments results about the effect of K p and T i on normal direction vibration, longitudinal vibration and the position step response show that this strategy suppresses vibration effectively while the motor's motion performance is not affected. The maximum reduction of vibration can be up to 40%. In addition, current test under rated load condition is also conducted and the results show that the control strategy can avoid the conflict between the direct-axis current and the quadrature

  11. High Frequency Adaptive Instability Suppression Controls in a Liquid-Fueled Combustor

    NASA Technical Reports Server (NTRS)

    Kopasakis, George

    2003-01-01

    This effort extends into high frequency (>500 Hz), an earlier developed adaptive control algorithm for the suppression of thermo-acoustic instabilities in a liquidfueled combustor. The earlier work covered the development of a controls algorithm for the suppression of a low frequency (280 Hz) combustion instability based on simulations, with no hardware testing involved. The work described here includes changes to the simulation and controller design necessary to control the high frequency instability, augmentations to the control algorithm to improve its performance, and finally hardware testing and results with an experimental combustor rig developed for the high frequency case. The Adaptive Sliding Phasor Averaged Control (ASPAC) algorithm modulates the fuel flow in the combustor with a control phase that continuously slides back and forth within the phase region that reduces the amplitude of the instability. The results demonstrate the power of the method - that it can identify and suppress the instability even when the instability amplitude is buried in the noise of the combustor pressure. The successful testing of the ASPAC approach helped complete an important NASA milestone to demonstrate advanced technologies for low-emission combustors.

  12. Nociceptin/Orphanin FQ Suppresses Adaptive Immune Responses in Vivo and at Picomolar Levels in Vitro

    PubMed Central

    Anton, Benito; Calva, Juan C.; Acevedo, Rodolfo; Salazar, Alberto; Matus, Maura; Flores, Anabel; Martinez, Martin; Adler, Martin W.; Gaughan, John P.; Eisenstein, Toby K.

    2014-01-01

    Nociceptin/orphanin FQ (N/OFQ), added in vitro to murine spleen cells in the picomolar range, suppressed antibody formation to sheep red blood cells in a primary and a secondary plaque-forming cell (PFC) assay. The activity of the peptide was maximal at 10−12 M, with an asymmetric U-shaped dose response curve that extended activity to 10−14 M. Suppression was not blocked by pretreatment with naloxone. Specificity of the suppressive response was shown using affinity purified rabbit antibodies against two N/OFQ peptides, and with a pharmacological antagonist. Antisera against both peptides were active, in a dose related manner, in neutralizing N/OFQ -mediated immunosuppression, when the peptide was used at concentrations from 10−12.3 to 10−11.6 M. In addition, nociceptin given in vivo by osmotic pump for 48 hr suppressed the capacity of spleen cells placed ex vivo to make an anti-sheep red blood cell response. These studies show that nociceptin directly inhibits an adaptive immune response, i.e. antibody formation, both in vitro and in vivo. PMID:20119853

  13. Innovative Adaptive Control Method Demonstrated for Active Suppression of Instabilities in Engine Combustors

    NASA Technical Reports Server (NTRS)

    Kopasakis, George

    2005-01-01

    This year, an improved adaptive-feedback control method was demonstrated that suppresses thermoacoustic instabilities in a liquid-fueled combustor of a type used in aircraft engines. Extensive research has been done to develop lean-burning (low fuel-to-air ratio) combustors that can reduce emissions throughout the mission cycle to reduce the environmental impact of aerospace propulsion systems. However, these lean-burning combustors are susceptible to thermoacoustic instabilities (high-frequency pressure waves), which can fatigue combustor components and even downstream turbine blades. This can significantly decrease the safe operating life of the combustor and turbine. Thus, suppressing the thermoacoustic combustor instabilities is an enabling technology for meeting the low-emission goals of the NASA Ultra-Efficient Engine Technology (UEET) Project.

  14. Active vibration suppression of self-excited structures using an adaptive LMS algorithm

    NASA Astrophysics Data System (ADS)

    Danda Roy, Indranil

    The purpose of this investigation is to study the feasibility of an adaptive feedforward controller for active flutter suppression in representative linear wing models. The ability of the controller to suppress limit-cycle oscillations in wing models having root springs with freeplay nonlinearities has also been studied. For the purposes of numerical simulation, mathematical models of a rigid and a flexible wing structure have been developed. The rigid wing model is represented by a simple three-degree-of-freedom airfoil while the flexible wing is modelled by a multi-degree-of-freedom finite element representation with beam elements for bending and rod elements for torsion. Control action is provided by one or more flaps attached to the trailing edge and extending along the entire wing span for the rigid model and a fraction of the wing span for the flexible model. Both two-dimensional quasi-steady aerodynamics and time-domain unsteady aerodynamics have been used to generate the airforces in the wing models. An adaptive feedforward controller has been designed based on the filtered-X Least Mean Squares (LMS) algorithm. The control configuration for the rigid wing model is single-input single-output (SISO) while both SISO and multi-input multi-output (MIMO) configurations have been applied on the flexible wing model. The controller includes an on-line adaptive system identification scheme which provides the LMS controller with a reasonably accurate model of the plant. This enables the adaptive controller to track time-varying parameters in the plant and provide effective control. The wing models in closed-loop exhibit highly damped responses at airspeeds where the open-loop responses are destructive. Simulations with the rigid and the flexible wing models in a time-varying airstream show a 63% and 53% increase, respectively, over their corresponding open-loop flutter airspeeds. The ability of the LMS controller to suppress wing store flutter in the two models has

  15. Adaptive Controls Method Demonstrated for the Active Suppression of Instabilities in Engine Combustors

    NASA Technical Reports Server (NTRS)

    Kopasakis, George

    2004-01-01

    An adaptive feedback control method was demonstrated that suppresses thermoacoustic instabilities in a liquid-fueled combustor of a type used in aircraft engines. Extensive research has been done to develop lean-burning (low fuel-to-air ratio) combustors that can reduce emissions throughout the mission cycle to reduce the environmental impact of aerospace propulsion systems. However, these lean-burning combustors are susceptible to thermoacoustic instabilities (high-frequency pressure waves), which can fatigue combustor components and even the downstream turbine blades. This can significantly decrease the safe operating lives of the combustor and turbine. Thus, suppressing the thermoacoustic combustor instabilities is an enabling technology for lean, low-emissions combustors under NASA's Propulsion and Power Program. This control methodology has been developed and tested in a partnership of the NASA Glenn Research Center, Pratt & Whitney, United Technologies Research Center, and the Georgia Institute of Technology. Initial combustor rig testing of the controls algorithm was completed during 2002. Subsequently, the test results were analyzed and improvements to the method were incorporated in 2003, which culminated in the final status of this controls algorithm. This control methodology is based on adaptive phase shifting. The combustor pressure oscillations are sensed and phase shifted, and a high-frequency fuel valve is actuated to put pressure oscillations into the combustor to cancel pressure oscillations produced by the instability.

  16. Adaptive immunity does not strongly suppress spontaneous tumors in a Sleeping Beauty model of cancer

    PubMed Central

    Rogers, Laura M.; Olivier, Alicia K.; Meyerholz, David K.; Dupuy, Adam J.

    2013-01-01

    The tumor immunosurveillance hypothesis describes a process by which the immune system recognizes and suppresses the growth of transformed cancer cells. A variety of epidemiological and experimental evidence supports this hypothesis. Nevertheless, there are a number of conflicting reports regarding the degree of immune protection conferred, the immune cell types responsible for protection, and the potential contributions of immunosuppressive therapies to tumor induction. The purpose of this study was to determine whether the adaptive immune system actively suppresses tumorigenesis in a Sleeping Beauty (SB) mouse model of cancer. SB transposon mutagenesis was performed in either a wild-type or immunocompromised (Rag2-null) background. Tumor latency and multiplicity were remarkably similar in both immune cohorts, suggesting that the adaptive immune system is not efficiently suppressing tumor formation in our model. Exceptions included skin tumors, which displayed increased multiplicity in wild-type animals, and leukemias, which developed with shorter latency in immune-deficient mice. Overall tumor distribution was also altered such that tumors affecting the gastrointestinal tract were more frequent and hemangiosarcomas were less frequent in immune-deficient mice compared to wild-type mice. Finally, genetic profiling of transposon-induced mutations identified significant differences in mutation prevalence for a number of genes, including Uba1. Taken together, these results indicate that B- and T-cells function to shape the genetic profile of tumors in various tumor types, despite being ineffective at clearing SB-induced tumors. This study represents the first forward genetic screen designed to examine tumor immunosurveillance mechanisms. PMID:23475219

  17. Performance benefits of adaptive, multimicrophone, interference-canceling systems in everyday environments

    NASA Astrophysics Data System (ADS)

    Desloge, Joseph G.; Zimmer, Martin J.; Zurek, Patrick M.

    2001-05-01

    Adaptive multimicrophone systems are currently used for a variety of noise-cancellation applications (such as hearing aids) to preserve signals arriving from a particular (target) direction while canceling other (jammer) signals in the environment. Although the performance of these systems is known to degrade with increasing reverberation, there are few measurements of adaptive performance in everyday reverberant environments. In this study, adaptive performance was compared to that of a simple, nonadaptive cardioid microphone to determine a measure of adaptive benefit. Both systems used recordings (at an Fs of 22050 Hz) from the same two omnidirectional microphones, which were separated by 1 cm. Four classes of environment were considered: outdoors, household, parking garage, and public establishment. Sources were either environmental noises (e.g., household appliances, restaurant noise) or a controlled noise source. In all situations, no target was present (i.e., all signals were jammers) to obtain maximal jammer cancellation. Adaptive processing was based upon the Griffiths-Jim generalized sidelobe canceller using filter lengths up to 400 points. Average intelligibility-weighted adaptive benefit levels at a source distance of 1 m were, at most, 1.5 dB for public establishments, 2 dB for household rooms and the parking garage, and 3 dB outdoors. [Work supported by NIOSH.

  18. Suppression of the GLUT4 adaptive response to exercise in fructose-fed rats

    PubMed Central

    Goyaram, Veeraj; Kohn, Tertius A.

    2013-01-01

    Exercise-induced increase in skeletal muscle GLUT4 expression is associated with hyperacetylation of histone H3 within a 350-bp DNA region surrounding the myocyte enhancer factor 2 (MEF2) element on the Glut4 promoter and increased binding of MEF2A. Previous studies have hypothesized that the increase in MEF2A binding is a result of improved accessibility of this DNA segment. Here, we investigated the impact of fructose consumption on exercise-induced GLUT4 adaptive response and directly measured the accessibility of the above segment to nucleases. Male Wistar rats (n = 30) were fed standard chow or chow + 10% fructose or maltodextrin drinks ad libitum for 13 days. In the last 6 days five animals per group performed 3 × 17-min bouts of intermittent swimming daily and five remained untrained. Triceps muscles were harvested and used to measure 1) GLUT4, pAMPK, and HDAC5 contents by Western blot, 2) accessibility of the DNA segment from intact nuclei using nuclease accessibility assays, 3) acetylation level of histone H3 and bound MEF2A by ChIP assays, and 4) glycogen content. Swim training increased GLUT4 content by ∼66% (P < 0.05) but fructose and maltodextrin feeding suppressed the adaptation. Accessibility of the DNA region to MNase and DNase I was significantly increased by swimming (∼2.75- and 5.75-fold, respectively) but was also suppressed in trained rats that consumed fructose or maltodextrin. Histone H3 acetylation and MEF2A binding paralleled the accessibility pattern. These findings indicate that both fructose and maltodextrin modulate the GLUT4 adaptive response to exercise by mechanisms involving chromatin remodeling at the Glut4 promoter. PMID:24326422

  19. Resistance to HF jamming interference in mobile radio networks by an adaptive, distributed reconfiguration technique

    NASA Astrophysics Data System (ADS)

    Baker, D. J.; Wieselthier, J. E.; Ephremides, A.; McGregor, D. N.

    1984-08-01

    In radio communication, interference (and in particular jamming) represents an important limitation to the rate and range of information transfer. In a radio network environment, a combination of relaying and other classes of interference-combatting methods, such as spread spectrum signaling, may achieve highly robust resistance to jamming. Since the presence of relays is an inherent characteristic of a network, it is possible to use some nodes as relays when previously existing direct links are disabled as a result of jamming. The purpose of this report is to show how a distributed algorithm can enable an HF radio network to reconfigure itself to combat various jamming threats. We present models for the communication range that is achievable through the use of HF groundwave signals under both benign and stressed conditions and for cases of narrowband and wideband signaling. The models are used in our simulations. These simulations show that the choice of best frequency for communication in an HF network should not depend solely on communication range in a benign environment.

  20. Performance analysis of multiple interference suppression over asynchronous/synchronous optical code-division multiple-access system based on complementary/prime/shifted coding scheme

    NASA Astrophysics Data System (ADS)

    Nieh, Ta-Chun; Yang, Chao-Chin; Huang, Jen-Fa

    2011-08-01

    A complete complementary/prime/shifted prime (CPS) code family for the optical code-division multiple-access (OCDMA) system is proposed. Based on the ability of complete complementary (CC) code, the multiple-access interference (MAI) can be suppressed and eliminated via spectral amplitude coding (SAC) OCDMA system under asynchronous/synchronous transmission. By utilizing the shifted prime (SP) code in the SAC scheme, the hardware implementation of encoder/decoder can be simplified with a reduced number of optical components, such as arrayed waveguide grating (AWG) and fiber Bragg grating (FBG). This system has a superior performance as compared to previous bipolar-bipolar coding OCDMA systems.

  1. Oligoribonucleotide (ORN) Interference-PCR (ORNi-PCR): A Simple Method for Suppressing PCR Amplification of Specific DNA Sequences Using ORNs

    PubMed Central

    Tanigawa, Naoki; Fujita, Toshitsugu; Fujii, Hodaka

    2014-01-01

    Polymerase chain reaction (PCR) amplification of multiple templates using common primers is used in a wide variety of molecular biological techniques. However, abundant templates sometimes obscure the amplification of minor species containing the same primer sequences. To overcome this challenge, we used oligoribonucleotides (ORNs) to inhibit amplification of undesired template sequences without affecting amplification of control sequences lacking complementarity to the ORNs. ORNs were effective at very low concentrations, with IC50 values for ORN-mediated suppression on the order of 10 nM. DNA polymerases that retain 3′–5′ exonuclease activity, such as KOD and Pfu polymerases, but not those that retain 5′–3′ exonuclease activity, such as Taq polymerase, could be used for ORN-mediated suppression. ORN interference-PCR (ORNi-PCR) technology should be a useful tool for both molecular biology research and clinical diagnosis. PMID:25405983

  2. The adaptive functions of sexual plasticity: the suppression and surreptitious expression of human sociosexuality.

    PubMed

    Josephs, Lawrence

    2012-06-01

    Tendencies toward non-monogamy and bisexual expression may constitute primate-wide predispositions that have been conserved in humans. This observation is supported by studies of sexual development and behavior in our primate relatives and sexually permissive premodern tribal cultures including hunter-gatherers. Nevertheless, even in sexually permissive societies, there may be considerable sexual possessiveness and jealousy as well as attempts at parental control of children's marital choices. This is associated with punitive revenge against unfaithful spouses and mate poaching rivals and parent/offspring conflict around marital choices. There is no paradise lost despite the greater sexual freedom. Humans may be adaptively designed to suppress each other's sexuality due to sexual jealousy and parental desires to control children's sexuality but also to surreptitiously evade those restrictions, though there is considerable cross-cultural variability in the level of sexual restrictiveness. PMID:23006118

  3. Design of a nonlinear adaptive filter for suppression of shuttle pilot-induced oscillation tendencies

    NASA Technical Reports Server (NTRS)

    Smith, J. W.; Edwards, J. W.

    1980-01-01

    Analysis of a longitudinal pilot-induced oscillation (PIO) experienced just prior to touchdown on the final flight of the space shuttle's approach landing tests indicated that the source of the problem was a combination of poor basic handling qualities aggravated by time delays through the digital flight control computer and rate limiting of the elevator actuators due to high pilot gain. A nonlinear PIO suppression (PIOS) filter was designed and developed to alleviate the vehicle's PIO tendencies by reducing the gain in the command path. From analytical and simulator studies it was shown that the PIOS filter, in an adaptive fashion, can attenuate the command path gain without adding phase lag to the system. With the pitch attitude loop of a simulated shuttle model closed, the PIOS filter increased the gain margin by a factor of about two.

  4. Staphylococcal toxic shock syndrome: superantigen-mediated enhancement of endotoxin shock and adaptive immune suppression.

    PubMed

    Kulhankova, Katarina; King, Jessica; Salgado-Pabón, Wilmara

    2014-08-01

    Infectious diseases caused by Staphylococcus aureus present a significant clinical and public health problem. S. aureus causes some of the most severe hospital-associated and community-acquired illnesses. Specifically, it is the leading cause of infective endocarditis and osteomyelitis, and the second leading cause of sepsis in the USA. While pathogenesis of S. aureus infections is at the center of current research, many questions remain about the mechanisms underlying staphylococcal toxic shock syndrome (TSS) and associated adaptive immune suppression. Both conditions are mediated by staphylococcal superantigens (SAgs)-secreted staphylococcal toxins that are major S. aureus virulence factors. Toxic shock syndrome toxin-1 (TSST-1) is the SAg responsible for almost all menstrual TSS cases in the USA. TSST-1, staphylococcal enterotoxin B and C are also responsible for most cases of non-menstrual TSS. While SAgs mediate all of the hallmark features of TSS, such as fever, rash, hypotension, and multi-organ dysfunction, they are also capable of enhancing the toxic effects of endogenous endotoxin. This interaction appears to be critical in mediating the severity of TSS and related mortality. In addition, interaction between SAgs and the host immune system has been recognized to result in a unique form of adaptive immune suppression, contributing to poor outcomes of S. aureus infections. Utilizing rabbit models of S. aureus infective endocarditis, pneumonia and sepsis, and molecular genetics techniques, we aim to elucidate the mechanisms of SAg and endotoxin synergism in the pathogenesis of TSS, and examine the cellular and molecular mechanisms underlying SAg-mediated immune dysfunction. PMID:24816557

  5. Adaptive noise suppression technique for dense 3D point cloud reconstructions from monocular vision

    NASA Astrophysics Data System (ADS)

    Diskin, Yakov; Asari, Vijayan K.

    2012-10-01

    Mobile vision-based autonomous vehicles use video frames from multiple angles to construct a 3D model of their environment. In this paper, we present a post-processing adaptive noise suppression technique to enhance the quality of the computed 3D model. Our near real-time reconstruction algorithm uses each pair of frames to compute the disparities of tracked feature points to translate the distance a feature has traveled within the frame in pixels into real world depth values. As a result these tracked feature points are plotted to form a dense and colorful point cloud. Due to the inevitable small vibrations in the camera and the mismatches within the feature tracking algorithm, the point cloud model contains a significant amount of misplaced points appearing as noise. The proposed noise suppression technique utilizes the spatial information of each point to unify points of similar texture and color into objects while simultaneously removing noise dissociated with any nearby objects. The noise filter combines all the points of similar depth into 2D layers throughout the point cloud model. By applying erosion and dilation techniques we are able to eliminate the unwanted floating points while retaining points of larger objects. To reverse the compression process, we transform the 2D layer back into the 3D model allowing points to return to their original position without the attached noise components. We evaluate the resulting noiseless point cloud by utilizing an unmanned ground vehicle to perform obstacle avoidance tasks. The contribution of the noise suppression technique is measured by evaluating the accuracy of the 3D reconstruction.

  6. Selective suppression of the human aryl hydrocarbon receptor function can be mediated through binding interference at the C-terminal half of the receptor.

    PubMed

    Ren, Lina; Thompson, John D; Cheung, Michael; Ngo, Katherine; Sung, Sarah; Leong, Scott; Chan, William K

    2016-05-01

    The human aryl hydrocarbon receptor is a cytosolic signaling molecule which affects immune response and aberrant cell growth. Canonical signaling of the receptor requires the recruitment of coactivators to the promoter region to remodel local chromatin structure. We predicted that interference of this recruitment would block the aryl hydrocarbon receptor function. To prove that, we employed phage display to identify nine peptides of twelve-amino-acid in length which target the C-terminal half of the human aryl hydrocarbon receptor, including the region where coactivators bind. Eight 12mer peptides, in the form of GFP fusion, suppressed the ligand-dependent transcription of six AHR target genes (cyp1a1, cyp1a2, cyp1b1, ugt1a1, nqo1, and ahrr) in different patterns in Hep3B cells, whereas the AHR antagonist CH-223191 suppressed all these target genes similarly. Three of the 12mer peptides (namely 11-3, 1-7, and 7-3) suppressed the 3MC-induced, CYP1A1-dependent EROD activity and the ROS production caused by benzo[a]pyrene. These 12mer peptides suppressed the AHR function synergistically with CH-223191. In conclusion, we provide evidence that targeting the C-terminal half of the human aryl hydrocarbon receptor is a viable, new approach to selectively block the receptor function. PMID:26970402

  7. Advances in RNA interference: dsRNA treatment in trees and grapevines for insect pest population suppression

    Technology Transfer Automated Retrieval System (TEKTRAN)

    RNA interference (RNAi) is a breakthrough technology that has significantly impacted contemporary approaches to control the damage caused by insect pests. Most well-known RNAi studies continue to rely on injecting the dsRNA molecules directly into the organism; this approach is not suitable for use...

  8. Interference-free wind-tunnel flows by adaptive-wall technology

    NASA Technical Reports Server (NTRS)

    Sears, W. R.; Vidal, R. J.; Erickson, J. C., Jr.; Ritter, A.

    1976-01-01

    The adaptive-wall or self-correcting wind tunnel has been proposed for such regimes as transonic and V/STOL where wall effects are large and cannot be corrected for. The power and generality of the concept are pointed out. In a two-dimensional transonic embodiment in the Calspan One-Foot Tunnel, the scheme has been shown to work at lower transonic Mach numbers. Several practical problems are cited, including instrumentation, the nature of the wall modification, and convergence of the iterative procedure. Moreover, questions of shock-wave neutralization at the wall and probable configuration of three-dimensional embodiments are discussed.

  9. Bovine brucellosis in wildlife: using adaptive management to improve understanding, technology and suppression.

    PubMed

    White, P J; Treanor, J J; Geremia, C; Wallen, R L; Blanton, D W; Hallac, D E

    2013-04-01

    Eradication of brucellosis from bison (Bison bison) and elk (Cervus elaphus) populations in the Greater Yellowstone Area is not possible with current technology. There are considerable uncertainties regarding the effectiveness of management techniques and unintended effects on wildlife behaviour and demography. However, adaptive management provides a framework for learning about the disease, improving suppression techniques, and lowering brucellosis transmission among wildlife and to cattle. Since it takes approximately three years after birth for female bison to become reproductively active and contribute to brucellosis transmission, there is an opportunity to implement actions such as vaccination and the selective removal of infectious bison based on age and assay results to reduce the potential for transmission. Older adult bison that have been exposed to the bacteria, but recovered from acute infection, could be retained in the population to provide some immunity (resistance) against future transmission. Through careful predictions, research, and monitoring, our understanding and technology will be improved and management actions can be adjusted to better achieve desired outcomes. PMID:23837383

  10. Vibration suppression in cutting tools using collocated piezoelectric sensors/actuators with an adaptive control algorithm

    SciTech Connect

    Radecki, Peter P; Farinholt, Kevin M; Park, Gyuhae; Bement, Matthew T

    2008-01-01

    The machining process is very important in many engineering applications. In high precision machining, surface finish is strongly correlated with vibrations and the dynamic interactions between the part and the cutting tool. Parameters affecting these vibrations and dynamic interactions, such as spindle speed, cut depth, feed rate, and the part's material properties can vary in real-time, resulting in unexpected or undesirable effects on the surface finish of the machining product. The focus of this research is the development of an improved machining process through the use of active vibration damping. The tool holder employs a high bandwidth piezoelectric actuator with an adaptive positive position feedback control algorithm for vibration and chatter suppression. In addition, instead of using external sensors, the proposed approach investigates the use of a collocated piezoelectric sensor for measuring the dynamic responses from machining processes. The performance of this method is evaluated by comparing the surface finishes obtained with active vibration control versus baseline uncontrolled cuts. Considerable improvement in surface finish (up to 50%) was observed for applications in modern day machining.

  11. Characterization and Suppression of the Electromagnetic Interference Induced Phase Shift in the JLab FEL Photo - Injector Advanced Drive Laser System

    SciTech Connect

    F. G. Wilson, D. Sexton, S. Zhang

    2011-09-01

    The drive laser for the photo-cathode gun used in the JLab Free Electron Laser (FEL) facility had been experiencing various phase shifts on the order of tens of degrees (>20{sup o} at 1497 MHz or >40ps) when changing the Advanced Drive Laser (ADL) [2][3][4] micro-pulse frequencies. These phase shifts introduced multiple complications when trying to setup the accelerator for operation, ultimately inhibiting the robustness and overall performance of the FEL. Through rigorous phase measurements and systematic characterizations, we determined that the phase shifts could be attributed to electromagnetic interference (EMI) coupling into the ADL phase control loop, and subsequently resolved the issue of phase shift to within tenths of a degree (<0.5{sup o} at 1497 MHz or <1ps). The diagnostic method developed and the knowledge gained through the entire process will prove to be invaluable for future designs of similar systems.

  12. Fetal ECG Extraction from Abdominal Signals: A Review on Suppression of Fundamental Power Line Interference Component and Its Harmonics

    PubMed Central

    Ţarălungă, Dragoş-Daniel; Ungureanu, Georgeta-Mihaela; Gussi, Ilinca; Strungaru, Rodica; Wolf, Werner

    2014-01-01

    Interference of power line (PLI) (fundamental frequency and its harmonics) is usually present in biopotential measurements. Despite all countermeasures, the PLI still corrupts physiological signals, for example, electromyograms (EMG), electroencephalograms (EEG), and electrocardiograms (ECG). When analyzing the fetal ECG (fECG) recorded on the maternal abdomen, the PLI represents a particular strong noise component, being sometimes 10 times greater than the fECG signal, and thus impairing the extraction of any useful information regarding the fetal health state. Many signal processing methods for cancelling the PLI from biopotentials are available in the literature. In this review study, six different principles are analyzed and discussed, and their performance is evaluated on simulated data (three different scenarios), based on five quantitative performance indices. PMID:24660020

  13. RNA interference suppression of the receptor tyrosine kinase Torso gene impaired pupation and adult emergence in Leptinotarsa decemlineata.

    PubMed

    Zhu, Tao-Tao; Meng, Qing-Wei; Guo, Wen-Chao; Li, Guo-Qing

    2015-12-01

    In Drosophila melanogaster prothoracic gland (PG) cells, Torso mediates prothoracicotropic hormone (PTTH)-triggered mitogen activated protein kinase (MAPK) pathway (consisting of four core components Ras, Raf, MEK and ERK) to stimulate ecdysteroidogenesis. In this study, LdTorso, LdRas, LdRaf and LdERK were cloned in Leptinotarsa decemlineata. The four genes were highly or moderately expressed in the larval prothoracic glands. At the first- to third-instar stages, their expression levels were higher just before and right after the molt, and were lower in the mid instars. At the fourth-instar stage, their transcript levels were higher before prepupal stage. RNA interference-mediated knockdown of LdTorso delayed larval development, increased pupal weight, and impaired pupation and adult emergence. Moreover, knockdown of LdTorso decreased the mRNA levels of LdRas, LdRaf and LdERK, repressed the transcription of two ecdysteroidogenesis genes (LdPHM and LdDIB), lowered 20E titer, and downregulated the expression of several 20E-response genes (LdEcR, LdUSP, LdHR3 and LdFTZ-F1). Furthermore, silencing of LdTorso induced the expression of a JH biosynthesis gene LdJHAMT, increased JH titer, and activated the transcription of a JH early-inducible gene LdKr-h1. Thus, our results suggest that Torso transduces PTTH-triggered MAPK signal to regulate ecdysteroidogenesis in the PGs in a non-drosophiline insect. PMID:26518287

  14. In vivo gene silencing of CD81 by lentiviral expression of small interference RNAs suppresses cocaine-induced behaviour.

    PubMed

    Bahi, Amine; Boyer, Frederic; Kolira, Manoj; Dreyer, Jean-Luc

    2005-03-01

    The tetraspanin CD81 is induced in the mesolimbic dopaminergic pathway after cocaine administration. To further investigate its role, a regulatable lentivirus (Lenti-CD81) bearing the CD81 gene under the control of a tetracycline-inducible promoter and lentiviruses expressing short hairpin RNA (shRNA) targeted against CD81 (Lenti-CD81-shRNAs) have been prepared. Infection of HEK293T cells in vitro with Lenti-CD81-shRNAs resulted in 96.5% gene silencing (from quantitative real-time PCR(qRT-PCR) and immunocytochemistry). In vivo delivery of Lenti-CD81-shRNA into the nucleus accumbens or ventral tegmental area resulted in 91.3 and 94% silencing of endogenous CD81, respectively. Stereotaxic injection of Lenti-CD81 into these regions, resulting in CD81 overexpression, induced a four- to fivefold increase in locomotor activity after chronic cocaine administration, which returned to basal levels when Lenti-CD81-shRNA had been coinjected or when CD81 expression was blocked by doxycycline. Furthermore, silencing endogenous CD81 in vivo resulted in a significant decrease in locomotor activity over controls, again suppressing cocaine-induced behaviour. PMID:15715673

  15. Oroxin B selectively induces tumor-suppressive ER stress and concurrently inhibits tumor-adaptive ER stress in B-lymphoma cells for effective anti-lymphoma therapy.

    PubMed

    Yang, Ping; Fu, Shilong; Cao, Zhifei; Liao, Huaidong; Huo, Zihe; Pan, Yanyan; Zhang, Gaochuan; Gao, Aidi; Zhou, Quansheng

    2015-10-15

    Cancer cells have both tumor-adaptive and -suppressive endoplasmic reticulum (ER) stress machineries that determine cell fate. In malignant tumors including lymphoma, constant activation of tumor-adaptive ER stress and concurrent reduction of tumor-suppressive ER stress favors cancer cell proliferation and tumor growth. Current ER stress-based anti-tumor drugs typically activate both tumor-adaptive and -suppressive ER stresses, resulting in low anti-cancer efficacy; hence, selective induction of tumor-suppressive ER stress and inhibition of tumor-adaptive ER stress are new strategies for novel anti-cancer drug discovery. Thus far, specific tumor-suppressive ER stress therapeutics have remained absent in clinical settings. In this study, we explored unique tumor-suppressive ER stress agents from the traditional Chinese medicinal herb Oroxylum indicum, and found that a small molecule oroxin B selectively induced tumor-suppressive ER stress in malignant lymphoma cells, but not in normal cells, effectively inhibited lymphoma growth in vivo, and significantly prolonged overall survival of lymphoma-xenografted mice without obvious toxicity. Mechanistic studies have revealed that the expression of key tumor-adaptive ER-stress gene GRP78 was notably suppressed by oroxin B via down-regulation of up-stream key signaling protein ATF6, while tumor-suppressive ER stress master gene DDIT3 was strikingly activated through activating the MKK3-p38 signaling pathway, correcting the imbalance between tumor-suppressive DDIT3 and tumor-adaptive GRP78 in lymphoma. Together, selective induction of unique tumor-suppressive ER stress and concurrent inhibition of tumor-adaptive ER stress in malignant lymphoma are new and feasible approaches for novel anti-lymphoma drug discovery and anti-lymphoma therapy. PMID:26253462

  16. New concepts in immunity to Neisseria gonorrhoeae: innate responses and suppression of adaptive immunity favor the pathogen, not the host.

    PubMed

    Liu, Yingru; Feinen, Brandon; Russell, Michael W

    2011-01-01

    It is well-known that gonorrhea can be acquired repeatedly with no apparent development of protective immunity arising from previous episodes of infection. Symptomatic infection is characterized by a purulent exudate, but the host response mechanisms are poorly understood. While the remarkable antigenic variability displayed by Neisseria gonorrhoeae and its capacity to inhibit complement activation allow it to evade destruction by the host's immune defenses, we propose that it also has the capacity to avoid inducing specific immune responses. In a mouse model of vaginal gonococcal infection, N. gonorrhoeae elicits Th17-driven inflammatory-immune responses, which recruit innate defense mechanisms including an influx of neutrophils. Concomitantly, N. gonorrhoeae suppresses Th1- and Th2-dependent adaptive immunity, including specific antibody responses, through a mechanism involving TGF-β and regulatory T cells. Blockade of TGF-β alleviates the suppression of specific anti-gonococcal responses and allows Th1 and Th2 responses to emerge with the generation of immune memory and protective immunity. Genital tract tissues are naturally rich in TGF-β, which fosters an immunosuppressive environment that is important in reproduction. In exploiting this niche, N. gonorrhoeae exemplifies a well-adapted pathogen that proactively elicits from its host innate responses that it can survive and concomitantly suppresses adaptive immunity. Comprehension of these mechanisms of gonococcal pathogenesis should allow the development of novel approaches to therapy and facilitate the development of an effective vaccine. PMID:21833308

  17. Moving Stimuli Are Less Effectively Masked Using Traditional Continuous Flash Suppression (CFS) Compared to a Moving Mondrian Mask (MMM): A Test Case for Feature-Selective Suppression and Retinotopic Adaptation

    PubMed Central

    Moors, Pieter; Wagemans, Johan; de-Wit, Lee

    2014-01-01

    Continuous flash suppression (CFS) is a powerful interocular suppression technique, which is often described as an effective means to reliably suppress stimuli from visual awareness. Suppression through CFS has been assumed to depend upon a reduction in (retinotopically specific) neural adaptation caused by the continual updating of the contents of the visual input to one eye. In this study, we started from the observation that suppressing a moving stimulus through CFS appeared to be more effective when using a mask that was actually more prone to retinotopically specific neural adaptation, but in which the properties of the mask were more similar to those of the to-be-suppressed stimulus. In two experiments, we find that using a moving Mondrian mask (i.e., one that includes motion) is more effective in suppressing a moving stimulus than a regular CFS mask. The observed pattern of results cannot be explained by a simple simulation that computes the degree of retinotopically specific neural adaptation over time, suggesting that this kind of neural adaptation does not play a large role in predicting the differences between conditions in this context. We also find some evidence consistent with the idea that the most effective CFS mask is the one that matches the properties (speed) of the suppressed stimulus. These results question the general importance of retinotopically specific neural adaptation in CFS, and potentially help to explain an implicit trend in the literature to adapt one’s CFS mask to match one’s to-be-suppressed stimuli. Finally, the results should help to guide the methodological development of future research where continuous suppression of moving stimuli is desired. PMID:24879378

  18. Lentiviral miR30-based RNA Interference against Heparanase Suppresses Melanoma Metastasis with Lower Liver and Lung Toxicity

    PubMed Central

    Liu, Xiao-yan; Tang, Qiu-su; Chen, Hong-chao; Jiang, Xiao-ling; Fang, Hong

    2013-01-01

    Aim: To construct short hairpin RNAs (shRNAs) and miR30-based shRNAs against heparanase (HPSE) to compare their safety and their effects on HPSE down-modulation in vitro and in vivo to develop a more ideal therapeutic RNA interference (RNAi) vector targeting HPSE. Methods: First, we constructed shRNAs and miR30-based shRNAs against HPSE (HPSE-shRNAs and HPSE-miRNAs) and packed them into lentiviral vectors. Next, we observed the effects of the shRNAs on knockdown for HPSE expression, adhesion, migration and invasion abilities in human malignant melanoma A375 cells in vitro. Furthermore, we compared the effects of the shRNAs on melanoma growth, metastasis and safety in xenograft models. Results: Our data showed that these artificial miRNAs targeting HPSE could be effective RNAi agents mediated by Pol II promoters in vitro and in vivo, although these miRNAs were not more potent than the HPSE-shRNAs. It was noted that obvious lung injuries, rarely revealed previously, as well as hepatotoxicity could be caused by lentivirus-mediated shRNAs (LV shRNAs) rather than lentivirus-mediated miRNAs (LV miRNAs) in vivo. Furthermore, enhanced expression of pro-inflammatory cytokines IL-6 and TGF-β1 and endogenous mmu-miR-21a-5p were detected in lung tissues of shRNAs groups, whereas the expression of mmu-let-7a-5p, mmu-let-7b-5p and mmu-let-7c-5p were down-regulated. Conclusion: These findings suggest that artificial miRNAs display an improved safety profile of lowered lung injury or hepatotoxicity relative to shRNAs in vivo. The mechanism of lung injuries caused by shRNAs may be correlated with changes of endogenous miRNAs in the lung. Our data here increase the flexibility of a miRNA-based RNAi system for functional genomic and gene therapy applications. PMID:23847439

  19. Stable RNA interference of ErbB-2 gene synergistic with epirubicin suppresses breast cancer growth in vitro and in vivo

    SciTech Connect

    Hu Xiaoqu; Su Fengxi; Qin Li; Jia Weijuan; Gong Chang; Yu Fengyan; Guo Jujiang; Song Erwei . E-mail: songerwei02@yahoo.com.cn

    2006-08-04

    Overexpression of human epidermal growth factor receptor-2 (Her2, ErbB-2) contributes to the progression and metastasis of breast cancer, implying that Her2 gene is a suitable target of RNA interference (RNAi) for breast cancer therapy. Here, we employed plasmid-mediated expression of 2 different Her2-shRNAs (pU6-Her2shRNAs) efficiently silenced the target gene expression on Her2 expressing SKBR-3 breast cancer cells in both mRNA and protein levels. Consequently, pU6-Her2shRNA increased apoptosis and reduced proliferation of SKBR-3 cells assayed by TUNEL and MTT, respectively. In vivo, intra-tumor injection of pU6-Her2shRNA inhibited the growth of SKBR-3 tumors inoculated subcutaneously in nude mice. Furthermore, pU6-Her2shRNA synergized the tumor suppression effect of epirubicin to SKBR-3 cells in vitro and implanted subcutaneously in nude mice. Therefore, we concluded that stable silencing of Her2 gene expression with plasmid expressing shRNA may hold great promise as a novel therapy for Her2 expressing breast cancers alone or in combination with anthracycline chemotherapy.

  20. The interruption of thyroid and interrenal and the inter-hormonal interference in fish: does it promote physiologic adaptation or maladaptation?

    PubMed

    Peter, Valsa S; Peter, M C Subhash

    2011-12-01

    Endocrines, the chief components of chemical centers which produce hormones in tune with intrinsic and extrinsic clues, create a chemical bridge between the organism and the environment. In fishes also hormones integrate and modulate many physiologic functions and its synthesis, release, biological actions and metabolic clearance are well regulated. Consequently, thyroid hormones (THs) and cortisol, the products of thyroid and interrenal axes, have been identified for their common integrative actions on metabolic and osmotic functions in fish. On the other hand, many anthropogenic chemical substances, popularly known as endocrine disrupting chemicals, have been shown to disrupt the hormone-receptor signaling pathways in a number fish species. These chemicals which are known for their ability to induce endocrine disruption particularly on thyroid and interrenals can cause malfunction or maladaptation of many vital processes which are involved in the development, growth and reproduction in fish. On the contrary, evidence is presented that the endocrine interrupting agents (EIAs) can cause interruption of thyroid and interrenals, resulting in physiologic compensatory mechanisms which can be adaptive, though such hormonal interactions are less recognized in fishes. The EIAs of physical, chemical and biological origins can specifically interrupt and modify the hormonal interactions between THs and cortisol, resulting in specific patterns of inter-hormonal interference. The physiologic analysis of these inter-hormonal interruptions during acclimation and post-acclimation to intrinsic or extrinsic EIAs reveals that combinations of anti-hormonal, pro-hormonal or stati-hormonal interference may help the fish to fine-tune their metabolic and osmotic performances as part of physiologic adaptation. This novel hypothesis on the phenomenon of inter-hormonal interference and its consequent physiologic interference during thyroid and interrenal interruption thus forms the basis of

  1. Adaptive antenna arrays for weak interfering signals

    NASA Technical Reports Server (NTRS)

    Gupta, I. J.

    1985-01-01

    The interference protection provided by adaptive antenna arrays to an Earth station or satellite receive antenna system is studied. The case where the interference is caused by the transmission from adjacent satellites or Earth stations whose signals inadverently enter the receiving system and interfere with the communication link is considered. Thus, the interfering signals are very weak. To increase the interference suppression, one can either decrease the thermal noise in the feedback loops or increase the gain of the auxiliary antennas in the interfering signal direction. Both methods are examined. It is shown that one may have to reduce the noise correlation to impractically low values and if directive auxiliary antennas are used, the auxiliary antenna size may have to be too large. One can, however, combine the two methods to achieve the specified interference suppression with reasonable requirements of noise decorrelation and auxiliary antenna size. Effects of the errors in the steering vector on the adaptive array performance are studied.

  2. Adaptive center determination for effective suppression of ring artifacts in tomography images

    SciTech Connect

    Jha, D. Sørensen, H. O. Dobberschütz, S.; Stipp, S. L. S.; Feidenhans'l, R.

    2014-10-06

    Ring artifacts on tomogram slices hinder image interpretation. They are caused by minor variation in the response from individual elements in a two dimensional (2D) X-ray detector. Polar space decreases the suppression complexity by transforming the rings on the tomogram slice to linear stripes. However, it requires that the center of rings lie at the origin of polar transformation. If this is not the case, all methods employing polar space become ineffective. We developed a method based on Gaussian localization of the ring center in Hough parameter space to assign the origin for the polar transformation. Thus, obtained linear stripes can be effectively suppressed by already existing methods. This effectively suppresses ring artifacts in the data from a variety of experimental setups, sample types and also handles tomograms that are previously cropped. This approach functions automatically, avoids the need for assumptions and preserves fine details, all critical for synchrotron based nanometer resolution tomography.

  3. Suppression of Background Odor Effect in Odor Sensing System Using Olfactory Adaptation Model

    NASA Astrophysics Data System (ADS)

    Ohba, Tsuneaki; Yamanaka, Takao

    In this study, a new method for suppressing the background odor effect is proposed. Since odor sensors response to background odors in addition to a target odor, it is difficult to detect the target odor information. In the conventional odor sensing systems, the effect of the background odors are compensated by subtracting the response to the background odors (the baseline response). Although this simple subtraction method is effective for constant background odors, it fails in the compensation for time-varying background odors. The proposed method for the background suppression is effective even for the time-varying background odors.

  4. Wind tunnel wall interference

    NASA Technical Reports Server (NTRS)

    Newman, Perry A.; Mineck, Raymond E.; Barnwell, Richard W.; Kemp, William B., Jr.

    1986-01-01

    About a decade ago, interest in alleviating wind tunnel wall interference was renewed by advances in computational aerodynamics, concepts of adaptive test section walls, and plans for high Reynolds number transonic test facilities. Selection of NASA Langley cryogenic concept for the National Transonic Facility (NTF) tended to focus the renewed wall interference efforts. A brief overview and current status of some Langley sponsored transonic wind tunnel wall interference research are presented. Included are continuing efforts in basic wall flow studies, wall interference assessment/correction procedures, and adaptive wall technology.

  5. Attentional Interference by Threat and Posttraumatic Stress Disorder: The Role of Thought Control Strategies

    PubMed Central

    Wisco, Blair E.; Pineles, Suzanne L.; Shipherd, Jillian C.; Marx, Brian P.

    2013-01-01

    Attentional interference by threat is associated with PTSD, but the mechanisms of this relationship remain unclear. Attentional interference might be related to increased use of maladaptive thought control strategies, such as suppressing unwanted thoughts (thought suppression) or replacing threatening thoughts with everyday concerns (worry), which increase PTSD risk. Conversely, attentional interference might be associated with reduced use of adaptive strategies, such as talking about threatening thoughts (social control) which decrease PTSD risk. This study tested if thought control strategies mediate the relationship between attentional interference and PTSD. Sixty-one male Vietnam-era veterans completed measures of PTSD symptoms and thought control strategies. Participants also completed a visual search task measuring attentional interference, which required participants to identify a target letter string among a group of threat or neutral words. Attentional interference by threat was related to PTSD symptoms, and mediation analyses revealed significant indirect effects of attentional interference through thought suppression and worry. Attentional interference was related to reexperiencing and avoidance, but not hyperarousal, symptom clusters. Thought suppression was a unique mediator for reexperiencing, whereas thought suppression and worry both mediated the relationship with avoidance. These results offer evidence for maladaptive thought control strategies as a mechanism linking attentional biases for threat to PTSD. PMID:23517445

  6. RNA Interference

    MedlinePlus

    ... NIGMS Home > Science Education > RNA Interference Fact Sheet RNA Interference Fact Sheet Tagline (Optional) Middle/Main Content Area What is RNA interference? RNA interference (RNAi) is a natural process ...

  7. RNA Interference Suppression of Genes in Glycosyl Transferase Families 43 and 47 in Wheat Starchy Endosperm Causes Large Decreases in Arabinoxylan Content1[C][W][OPEN

    PubMed Central

    Lovegrove, Alison; Wilkinson, Mark D.; Freeman, Jackie; Pellny, Till K.; Tosi, Paola; Saulnier, Luc; Shewry, Peter R.; Mitchell, Rowan A.C.

    2013-01-01

    The cell walls of wheat (Triticum aestivum) starchy endosperm are dominated by arabinoxylan (AX), accounting for 65% to 70% of the polysaccharide content. Genes within two glycosyl transferase (GT) families, GT43 (IRREGULAR XYLEM9 [IRX9] and IRX14) and GT47 (IRX10), have previously been shown to be involved in the synthesis of the xylan backbone in Arabidopsis, and close homologs of these have been implicated in the synthesis of xylan in other species. Here, homologs of IRX10 TaGT47_2 and IRX9 TaGT43_2, which are highly expressed in wheat starchy endosperm cells, were suppressed by RNA interference (RNAi) constructs driven by a starchy endosperm-specific promoter. The total amount of AX was decreased by 40% to 50% and the degree of arabinosylation was increased by 25% to 30% in transgenic lines carrying either of the transgenes. The cell walls of starchy endosperm in sections of grain from TaGT43_2 and TaGT47_2 RNAi transgenics showed decreased immunolabeling for xylan and arabinoxylan epitopes and approximately 50% decreased cell wall thickness compared with controls. The proportion of AX that was water soluble was not significantly affected, but average AX polymer chain length was decreased in both TaGT43_2 and TaGT47_2 RNAi transgenics. However, the long AX chains seen in controls were absent in TaGT43_2 RNAi transgenics but still present in TaGT47_2 RNAi transgenics. The results support an emerging picture of IRX9-like and IRX10-like proteins acting as key components in the xylan synthesis machinery in both dicots and grasses. Since AX is the main component of dietary fiber in wheat foods, the TaGT43_2 and TaGT47_2 genes are of major importance to human nutrition. PMID:23878080

  8. Adaptive Noise Suppression of Pediatric Lung Auscultations With Real Applications to Noisy Clinical Settings in Developing Countries

    PubMed Central

    Emmanouilidou, Dimitra; McCollum, Eric D.; Park, Daniel E.

    2015-01-01

    Goal Chest auscultation constitutes a portable low-cost tool widely used for respiratory disease detection. Though it offers a powerful means of pulmonary examination, it remains riddled with a number of issues that limit its diagnostic capability. Particularly, patient agitation (especially in children), background chatter, and other environmental noises often contaminate the auscultation, hence affecting the clarity of the lung sound itself. This paper proposes an automated multiband denoising scheme for improving the quality of auscultation signals against heavy background contaminations. Methods The algorithm works on a simple two-microphone setup, dynamically adapts to the background noise and suppresses contaminations while successfully preserving the lung sound content. The proposed scheme is refined to offset maximal noise suppression against maintaining the integrity of the lung signal, particularly its unknown adventitious components that provide the most informative diagnostic value during lung pathology. Results The algorithm is applied to digital recordings obtained in the field in a busy clinic in West Africa and evaluated using objective signal fidelity measures and perceptual listening tests performed by a panel of licensed physicians. A strong preference of the enhanced sounds is revealed. Significance The strengths and benefits of the proposed method lie in the simple automated setup and its adaptive nature, both fundamental conditions for everyday clinical applicability. It can be simply extended to a real-time implementation, and integrated with lung sound acquisition protocols. PMID:25879837

  9. Suppression of Adaptive Immune Cell Activation Does Not Alter Innate Immune Adipose Inflammation or Insulin Resistance in Obesity

    PubMed Central

    Subramanian, Manikandan; Ozcan, Lale; Ghorpade, Devram Sampat; Ferrante, Anthony W.; Tabas, Ira

    2015-01-01

    Obesity-induced inflammation in visceral adipose tissue (VAT) is a major contributor to insulin resistance and type 2 diabetes. Whereas innate immune cells, notably macrophages, contribute to visceral adipose tissue (VAT) inflammation and insulin resistance, the role of adaptive immunity is less well defined. To address this critical gap, we used a model in which endogenous activation of T cells was suppressed in obese mice by blocking MyD88-mediated maturation of CD11c+ antigen-presenting cells. VAT CD11c+ cells from Cd11cCre+Myd88fl/fl vs. control Myd88fl/fl mice were defective in activating T cells in vitro, and VAT T and B cell activation was markedly reduced in Cd11cCre+Myd88fl/fl obese mice. However, neither macrophage-mediated VAT inflammation nor systemic inflammation were altered in Cd11cCre+Myd88fl/fl mice, thereby enabling a focused analysis on adaptive immunity. Unexpectedly, fasting blood glucose, plasma insulin, and the glucose response to glucose and insulin were completely unaltered in Cd11cCre+Myd88fl/fl vs. control obese mice. Thus, CD11c+ cells activate VAT T and B cells in obese mice, but suppression of this process does not have a discernible effect on macrophage-mediated VAT inflammation or systemic glucose homeostasis. PMID:26317499

  10. Adenosine and Prostaglandin E2 Cooperate in the Suppression of Immune Responses Mediated by Adaptive Regulatory T Cells*

    PubMed Central

    Mandapathil, Magis; Szczepanski, Miroslaw J.; Szajnik, Marta; Ren, Jin; Jackson, Edwin K.; Johnson, Jonas T.; Gorelik, Elieser; Lang, Stephan; Whiteside, Theresa L.

    2010-01-01

    Adaptive regulatory T cells (Tr1) are induced in the periphery upon encountering cognate antigens. In cancer, their frequency is increased; however, Tr1-mediated suppression mechanisms are not yet defined. Here, we evaluate the simultaneous involvement of ectonucleotidases (CD39/CD73) and cyclooxygenase 2 (COX-2) in Tr1-mediated suppression. Human Tr1 cells were generated from peripheral blood mononuclear cell-derived, sorted CD4+CD25− T cells and incubated with autologous immature dendritic cells, irradiated COX-2+ or COX-2− tumor cells, and IL-2, IL-10, and IL-15 (each at 10–15 IU/ml) for 10 days as described (Bergmann, C., Strauss, L., Zeidler, R., Lang, S., and Whiteside, T. L. (2007) Cancer Immunol. Immunother. 56, 1429–1442). Tr1 were phenotyped by multicolor flow cytometry, and suppression of proliferating responder cells was assessed in carboxyfluorescein diacetate succinimidyl ester-based assays. ATP hydrolysis was measured using a luciferase detection assay, and levels of adenosine or prostaglandin E2 (PGE2) in cell supernatants were analyzed by mass spectrometry or ELISA, respectively. Intracellular cAMP levels were measured by enzyme immunoassay. The COX-2+ tumor induced a greater number of Tr1 than COX-2− tumor (p < 0.05). Tr1 induced by COX-2+ tumor were more suppressive, hydrolyzed more exogenous ATP (p < 0.05), and produced higher levels of adenosine and PGE2 (p < 0.05) than Tr1 induced by COX-2− tumor. Inhibitors of ectonucleotidase activity, A2A and EP2 receptor antagonists, or an inhibitor of the PKA type I decreased Tr1-mediated suppression (p < 0.05), whereas rolipram, a PDE4 inhibitor, increased the intracellular cAMP level in responder cells and their susceptibility to Tr1-mediated suppression. Tr1 present in tumors or the peripheral blood of head and neck squamous cell carcinoma patients co-expressed COX-2, CD39, and CD73. A concomitant inhibition of PGE2 and adenosine via the common intracellular cAMP pathway might be a novel

  11. Effects of Adaptation Rate and Noise Suppression on the Intelligibility of Compressed-Envelope Based Speech

    PubMed Central

    Lai, Ying-Hui; Tsao, Yu; Chen, Fei

    2015-01-01

    Temporal envelope is the primary acoustic cue used in most cochlear implant (CI) speech processors to elicit speech perception for patients fitted with CI devices. Envelope compression narrows down envelope dynamic range and accordingly degrades speech understanding abilities of CI users, especially under challenging listening conditions (e.g., in noise). A new adaptive envelope compression (AEC) strategy was proposed recently, which in contrast to the traditional static envelope compression, is effective at enhancing the modulation depth of envelope waveform by making best use of its dynamic range and thus improving the intelligibility of envelope-based speech. The present study further explored the effect of adaptation rate in envelope compression on the intelligibility of compressed-envelope based speech. Moreover, since noise reduction is another essential unit in modern CI systems, the compatibility of AEC and noise reduction was also investigated. In this study, listening experiments were carried out by presenting vocoded sentences to normal hearing listeners for recognition. Experimental results demonstrated that the adaptation rate in envelope compression had a notable effect on the speech intelligibility performance of the AEC strategy. By specifying a suitable adaptation rate, speech intelligibility could be enhanced significantly in noise compared to when using static envelope compression. Moreover, results confirmed that the AEC strategy was suitable for combining with noise reduction to improve the intelligibility of envelope-based speech in noise. PMID:26196508

  12. Identification of heat stress-responsive genes in heat-adapted thermal Agrostis scabra by suppression subtractive hybridization.

    PubMed

    Tian, Jiang; Belanger, Faith C; Huang, Bingru

    2009-04-01

    To gain insights into molecular mechanisms of grass tolerance to heat stress, we constructed a suppression subtractive cDNA library to identify heat-responsive genes for a C(3) grass species, thermal Agrostis scabra adapted to heat stress in geothermal areas in Yellowstone National Park. Plants were exposed to 20 degrees C (control) or 35 degrees C for 12d. The SSH analysis was performed with control samples as the driver and heat-stressed samples as the tester. Differentially expressed cDNA fragments were cloned to screen the heat up-regulated library. The SSH analysis identified 120 non-redundant putative heat-responsive cDNAs out of 1180 clones. Genes with homology to known proteins were categorized into six functional groups, with the largest group of genes involved in stress/defense, followed by the group of genes related to protein metabolism. Immunoblot analysis confirmed increases in transcripts of selected genes under heat stress. Transcripts of seven and eight genes were strongly enhanced or induced in shoots and roots, respectively, while two genes were only induced in roots under heat stress. The heat up-regulated genes in thermal A. scabra adapted to long-term heat stress are potential candidate genes for engineering stress-tolerant grasses and for revealing molecular mechanisms of grass adaptation to heat stress. PMID:18950897

  13. Synchrony suppression in ensembles of coupled oscillators via adaptive vanishing feedback

    NASA Astrophysics Data System (ADS)

    Montaseri, Ghazal; Javad Yazdanpanah, Mohammad; Pikovsky, Arkady; Rosenblum, Michael

    2013-09-01

    Synchronization and emergence of a collective mode is a general phenomenon, frequently observed in ensembles of coupled self-sustained oscillators of various natures. In several circumstances, in particular in cases of neurological pathologies, this state of the active medium is undesirable. Destruction of this state by a specially designed stimulation is a challenge of high clinical relevance. Typically, the precise effect of an external action on the ensemble is unknown, since the microscopic description of the oscillators and their interactions are not available. We show that, desynchronization in case of a large degree of uncertainty about important features of the system is nevertheless possible; it can be achieved by virtue of a feedback loop with an additional adaptation of parameters. The adaptation also ensures desynchronization of ensembles with non-stationary, time-varying parameters. We perform the stability analysis of the feedback-controlled system and demonstrate efficient destruction of synchrony for several models, including those of spiking and bursting neurons.

  14. Development of Tremor Suppression Control System Using Adaptive Filter and Its Application to Meal-assist Robot

    NASA Astrophysics Data System (ADS)

    Yano, Ken'ichi; Ohara, Eiichi; Horihata, Satoshi; Aoki, Takaaki; Nishimoto, Yutaka

    A robot that supports independent living by assisting with eating and other activities which use the operator's own hand would be helpful for people suffering from tremors of the hand or any other body part. The proposed system using adaptive filter estimates tremor frequencies with a time-varying property and individual differences online. In this study, the estimated frequency is used to adjusting the tremor suppression filter which insulates the voluntary motion signal from the sensor signal containing tremor components. These system are integrated into the control system of the Meal-Assist Robot. As a result, the developed system makes it possible for the person with a tremor to manipulate the supporting robot without causing operability to deteriorate and without hazards due to improper operation.

  15. Multiscale model for the effects of adaptive immunity suppression on the viral therapy of cancer

    NASA Astrophysics Data System (ADS)

    Paiva, Leticia R.; Silva, Hallan S.; Ferreira, Silvio C.; Martins, Marcelo L.

    2013-04-01

    Oncolytic virotherapy—the use of viruses that specifically kill tumor cells—is an innovative and highly promising route for treating cancer. However, its therapeutic outcomes are mainly impaired by the host immune response to the viral infection. In this paper, we propose a multiscale mathematical model to study how the immune response interferes with the viral oncolytic activity. The model assumes that cytotoxic T cells can induce apoptosis in infected cancer cells and that free viruses can be inactivated by neutralizing antibodies or cleared at a constant rate by the innate immune response. Our simulations suggest that reprogramming the immune microenvironment in tumors could substantially enhance the oncolytic virotherapy in immune-competent hosts. Viable routes to such reprogramming are either in situ virus-mediated impairing of CD8+ T cells motility or blockade of B and T lymphocytes recruitment. Our theoretical results can shed light on the design of viral vectors or new protocols with neat potential impacts on the clinical practice.

  16. Forskolin Suppresses Delayed-Rectifier K+ Currents and Enhances Spike Frequency-Dependent Adaptation of Sympathetic Neurons

    PubMed Central

    Castro, Elena; Cruzblanca, Humberto

    2015-01-01

    In signal transduction research natural or synthetic molecules are commonly used to target a great variety of signaling proteins. For instance, forskolin, a diterpene activator of adenylate cyclase, has been widely used in cellular preparations to increase the intracellular cAMP level. However, it has been shown that forskolin directly inhibits some cloned K+ channels, which in excitable cells set up the resting membrane potential, the shape of action potential and regulate repetitive firing. Despite the growing evidence indicating that K+ channels are blocked by forskolin, there are no studies yet assessing the impact of this mechanism of action on neuron excitability and firing patterns. In sympathetic neurons, we find that forskolin and its derivative 1,9-Dideoxyforskolin, reversibly suppress the delayed rectifier K+ current (IKV). Besides, forskolin reduced the spike afterhyperpolarization and enhanced the spike frequency-dependent adaptation. Given that IKV is mostly generated by Kv2.1 channels, HEK-293 cells were transfected with cDNA encoding for the Kv2.1 α subunit, to characterize the mechanism of forskolin action. Both drugs reversible suppressed the Kv2.1-mediated K+ currents. Forskolin inhibited Kv2.1 currents and IKV with an IC50 of ~32 μM and ~24 µM, respectively. Besides, the drug induced an apparent current inactivation and slowed-down current deactivation. We suggest that forskolin reduces the excitability of sympathetic neurons by enhancing the spike frequency-dependent adaptation, partially through a direct block of their native Kv2.1 channels. PMID:25962132

  17. Protection of the main maximum in adaptive antenna arrays

    NASA Astrophysics Data System (ADS)

    Pistolkors, A. A.

    1980-12-01

    An adaptive algorithm based on the solution of the problem of minimizing the noise at the output of an array when a constraint is imposed on the main maximum direction is discussed. The suppression depth for the cases of one and two interferences and the enhancement of the direction-finding capability and resolution of an adaptive array are investigated.

  18. Automatic artifact suppression in simultaneous tDCS-EEG using adaptive filtering.

    PubMed

    Mancini, Matteo; Pellicciari, Maria Concetta; Brignani, Debora; Mauri, Piercarlo; De Marchis, Cristiano; Miniussi, Carlo; Conforto, Silvia

    2015-08-01

    Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method that can be used in cognitive and clinical protocols in order to modulate neural activity. Although some macro effects are known, the underlying mechanisms are still not clear. tDCS in combination with electroencephalography (EEG) could help to understand these mechanisms from a neural point of view. However, simultaneous tDCS-EEG still remains challenging because of the artifacts that affect the recorded signals. In this paper, an automated artifact cancellation method based on adaptive filtering is proposed. Using independent component analysis (ICA), the artifacts were characterized using data from both a phantom and a group of healthy subjects. The resulting filter can successfully remove tDCS-related artifacts during anodal and cathodal stimulations. PMID:26736856

  19. Suppression of antigen-specific adaptive immunity by IL-37 via induction of tolerogenic dendritic cells

    PubMed Central

    Luo, Yuchun; Cai, Xiangna; Liu, Sucai; Wang, Sen; Nold-Petry, Claudia A.; Nold, Marcel F.; Bufler, Philip; Norris, David; Dinarello, Charles A.; Fujita, Mayumi

    2014-01-01

    IL-1 family member IL-37 limits innate inflammation in models of colitis and LPS-induced shock, but a role in adaptive immunity remains unknown. Here, we studied mice expressing human IL-37b isoform (IL-37tg) subjected to skin contact hypersensitivity (CHS) to dinitrofluorobenzene. CHS challenge to the hapten was significantly decreased in IL-37tg mice compared with wild-type (WT) mice (−61%; P < 0.001 at 48 h). Skin dendritic cells (DCs) were present and migrated to lymph nodes after antigen uptake in IL-37tg mice. When hapten-sensitized DCs were adoptively transferred to WT mice, antigen challenge was greatly impaired in mice receiving DCs from IL-37tg mice compared with those receiving DCs from WT mice (−60%; P < 0.01 at 48 h). In DCs isolated from IL-37tg mice, LPS-induced increase of MHC II and costimulatory molecule CD40 was reduced by 51 and 31%, respectively. In these DCs, release of IL-1β, IL-6, and IL-12 was reduced whereas IL-10 secretion increased (37%). Consistent with these findings, DCs from IL-37tg mice exhibited a lower ability to stimulate syngeneic and allogeneic naive T cells as well as antigen-specific T cells and displayed enhanced induction of T regulatory (Treg) cells (86%; P < 0.001) in vitro. Histological analysis of CHS skin in mice receiving hapten-sensitized DCs from IL-37tg mice revealed a marked reduction in CD8+ T cells (−74%) but an increase in Treg cells (2.6-fold). Together, these findings reveal that DCs expressing IL-37 are tolerogenic, thereby impairing activation of effector T-cell responses and inducing Treg cells. IL-37 thus emerges as an inhibitor of adaptive immunity. PMID:25294929

  20. Suppression of hLRH-1 mediated by a DNA vector-based RNA interference results in cell cycle arrest and induction of apoptosis in hepatocellular carcinoma cell BEL-7402

    SciTech Connect

    Wang Shuiliang; Lan Fenghua; Huang Lianghu; Dong Lihong; Zhu Zhongyong; Li Zonghai; Xie Youhua; Fu Jiliang . E-mail: fu825@mail.tongji.edu.cn

    2005-08-05

    RNA interference (RNAi) is the process by which double-stranded RNA directs sequence-specific degradation of mRNA. A DNA vector-based approach has been shown to be able to trigger RNA interference in mammalian cells successfully. LRH-1 is an orphan nuclear receptor predominantly expressed in tissues of endodermal origin, where it controls development and cholesterol homeostasis. In the present study, we demonstrated that the expression of hLRH-1 and cyclin E1 in BEL-7402 cells could be suppressed by up to {approx}80% via DNA vector-based RNA interference. The suppression of hLRH-1 resulted in cell cycle arrest mediated by the down-regulation of cyclin E1. Induction of apoptosis and down-regulation of Gadd45{beta} were also shown in hLRH-1 knock down BEL-7402 cells. These results, together with the findings that Gadd45{beta} remained unchanged in cyclin E1 RNAi cells, suggested that the induction of apoptosis by knock down of hLRH-1 was closely related to the down-regulation of Gadd45{beta}.

  1. Suppression Measured from Chinchilla Auditory-Nerve-Fiber Responses Following Noise-Induced Hearing Loss: Adaptive-Tracking and Systems-Identification Approaches.

    PubMed

    Sayles, Mark; Walls, Michael K; Heinz, Michael G

    2016-01-01

    The compressive nonlinearity of cochlear signal transduction, reflecting outer-hair-cell function, manifests as suppressive spectral interactions; e.g., two-tone suppression. Moreover, for broadband sounds, there are multiple interactions between frequency components. These frequency-dependent nonlinearities are important for neural coding of complex sounds, such as speech. Acoustic-trauma-induced outer-hair-cell damage is associated with loss of nonlinearity, which auditory prostheses attempt to restore with, e.g., "multi-channel dynamic compression" algorithms.Neurophysiological data on suppression in hearing-impaired (HI) mammals are limited. We present data on firing-rate suppression measured in auditory-nerve-fiber responses in a chinchilla model of noise-induced hearing loss, and in normal-hearing (NH) controls at equal sensation level. Hearing-impaired (HI) animals had elevated single-fiber excitatory thresholds (by ~ 20-40 dB), broadened frequency tuning, and reduced-magnitude distortion-product otoacoustic emissions; consistent with mixed inner- and outer-hair-cell pathology. We characterized suppression using two approaches: adaptive tracking of two-tone-suppression threshold (62 NH, and 35 HI fibers), and Wiener-kernel analyses of responses to broadband noise (91 NH, and 148 HI fibers). Suppression-threshold tuning curves showed sensitive low-side suppression for NH and HI animals. High-side suppression thresholds were elevated in HI animals, to the same extent as excitatory thresholds. We factored second-order Wiener-kernels into excitatory and suppressive sub-kernels to quantify the relative strength of suppression. We found a small decrease in suppression in HI fibers, which correlated with broadened tuning. These data will help guide novel amplification strategies, particularly for complex listening situations (e.g., speech in noise), in which current hearing aids struggle to restore intelligibility. PMID:27080669

  2. Image copy-move forgery detection based on sped-up robust features descriptor and adaptive minimal-maximal suppression

    NASA Astrophysics Data System (ADS)

    Yang, Bin; Sun, Xingming; Xin, Xiangyang; Hu, Weifeng; Wu, Youxin

    2015-11-01

    Region duplication is a simple and effective operation to create digital image forgeries, where a continuous portion of pixels in an image is copied and pasted to a different location in the same image. Many prior copy-move forgery detection methods suffer from their inability to detect the duplicated region, which is subjected to various geometric transformations. A keypoint-based approach is proposed to detect the copy-move forgery in an image. Our method starts by extracting the keypoints through a fast Hessian detector. Then the adaptive minimal-maximal suppression (AMMS) strategy is developed for distributing the keypoints evenly throughout an image. By using AMMS and a sped-up robust feature descriptor, the proposed method is able to deal with the problem of insufficient keypoints in the almost uniform area. Finally, the geometric transformation performed in cloning is recovered by using the maximum likelihood estimation of the homography. Experimental results show the efficacy of this technique in detecting copy-move forgeries and estimating the geometric transformation parameters. Compared with the state of the art, our approach obtains a higher true positive rate and a lower false positive rate.

  3. Cerebellar cathodal tDCS interferes with recalibration and spatial realignment during prism adaptation procedure in healthy subjects.

    PubMed

    Panico, Francesco; Sagliano, Laura; Grossi, Dario; Trojano, Luigi

    2016-06-01

    The aim of this study is to clarify the specific role of the cerebellum during prism adaptation procedure (PAP), considering its involvement in early prism exposure (i.e., in the recalibration process) and in post-exposure phase (i.e., in the after-effect, related to spatial realignment). For this purpose we interfered with cerebellar activity by means of cathodal transcranial direct current stimulation (tDCS), while young healthy individuals were asked to perform a pointing task on a touch screen before, during and after wearing base-left prism glasses. The distance from the target dot in each trial (in terms of pixels) on horizontal and vertical axes was recorded and served as an index of accuracy. Results on horizontal axis, that was shifted by prism glasses, revealed that participants who received cathodal stimulation showed increased rightward deviation from the actual position of the target while wearing prisms and a larger leftward deviation from the target after prisms removal. Results on vertical axis, in which no shift was induced, revealed a general trend in the two groups to improve accuracy through the different phases of the task, and a trend, more visible in cathodal stimulated participants, to worsen accuracy from the first to the last movements in each phase. Data on horizontal axis allow to confirm that the cerebellum is involved in all stages of PAP, contributing to early strategic recalibration process, as well as to spatial realignment. On vertical axis, the improving performance across the different stages of the task and the worsening accuracy within each task phase can be ascribed, respectively, to a learning process and to the task-related fatigue. PMID:27031676

  4. Face adaptation depends on seeing the face.

    PubMed

    Moradi, Farshad; Koch, Christof; Shimojo, Shinsuke

    2005-01-01

    Retinal input that is suppressed from visual awareness can nevertheless produce measurable aftereffects, revealing neural processes that do not directly result in a conscious percept. We here report that the face identity-specific aftereffect requires a visible face; it is effectively cancelled by binocular suppression or by inattentional blindness of the inducing face. Conversely, the same suppression does not interfere with the orientation-specific aftereffect. Thus, the competition between incompatible or interfering visual inputs to reach awareness is resolved before those aspects of information that are exploited in face identification are processed. We also found that the face aftereffect remained intact when the visual distracters in the inattention experiment were replaced with auditory distracters. Thus, cross-modal or cognitive interference that does not affect the visibility of the face does not interfere with the face aftereffect. We conclude that adaptation to face identity depends on seeing the face. PMID:15629711

  5. Measured reflectance suppressed by thin-film interference of crude oil smeared on glass - as on vitrinite in coal or petroliferous rocks

    USGS Publications Warehouse

    Bostick, Neely

    2011-01-01

    The tool of measuring "vitrinite reflectance" under a microscope has great value in petroleum exploration and coal utilization, and the reflectance is a simple number, such as 1.4% Ro, with some slight variations depending on technique. Sample collection, preparation and measurement are simple and many sedimentary rocks yield vitrinite. However, the reported number can lead one astray if its origin and quality are not fully understood. I analyze here just one factor, "smear" of crude oil on the polished surface (from the sample), which may reduce reflectance because of thin-film interference. Some other causes of error are listed in an addendum to this note.

  6. Implementation of LSCMA adaptive array terminal for mobile satellite communications

    NASA Astrophysics Data System (ADS)

    Zhou, Shun; Wang, Huali; Xu, Zhijun

    2007-11-01

    This paper considers the application of adaptive array antenna based on the least squares constant modulus algorithm (LSCMA) for interference rejection in mobile SATCOM terminals. A two-element adaptive array scheme is implemented with a combination of ADI TS201S DSP chips and Altera Stratix II FPGA device, which makes a cooperating computation for adaptive beamforming. Its interference suppressing performance is verified via Matlab simulations. Digital hardware system is implemented to execute the operations of LSCMA beamforming algorithm that is represented by an algorithm flowchart. The result of simulations and test indicate that this scheme can improve the anti-jamming performance of terminals.

  7. Suppression of optical beat interference-noise in orthogonal frequency division multiple access-passive optical network link using self-homodyne balanced detection

    NASA Astrophysics Data System (ADS)

    Won, Yong-Yuk; Jung, Sang-Min; Han, Sang-Kook

    2014-08-01

    A new technique, which reduces optical beat interference (OBI) noise in orthogonal frequency division multiple access-passive optical network (OFDMA-PON) links, is proposed. A self-homodyne balanced detection, which uses a single laser for the optical line terminal (OLT) as well as for the optical network unit (ONU), reduces OBI noise and also improves the signal to noise ratio (SNR) of the discrete multi-tone (DMT) signal. The proposed scheme is verified by transmitting quadrature phase shift keying (QPSK)-modulated DMT signal over a 20-km single mode fiber. The optical signal to noise ratio (OSNR), that is required for BER of 10-5, is reduced by 2 dB in the balanced detection compared with a single channel due to the cancellation of OBI noise in conjunction with the local laser.

  8. Loss-of-function of OsSTN8 suppresses the photosystem II core protein phosphorylation and interferes with the photosystem II repair mechanism in rice (Oryza sativa).

    PubMed

    Nath, Krishna; Poudyal, Roshan Sharma; Eom, Joon-Seob; Park, Yu Shin; Zulfugarov, Ismayil S; Mishra, Sujata R; Tovuu, Altanzaya; Ryoo, Nayeoon; Yoon, Ho-Sung; Nam, Hong Gil; An, Gynheung; Jeon, Jong-Seong; Lee, Choon-Hwan

    2013-11-01

    STN8 kinase is involved in photosystem II (PSII) core protein phosphorylation (PCPP). To examine the role of PCPP in PSII repair during high light (HL) illumination, we characterized a T-DNA insertional knockout mutant of the rice (Oryza sativa) STN8 gene. In this osstn8 mutant, PCPP was significantly suppressed, and the grana were thin and elongated. Upon HL illumination, PSII was strongly inactivated in the mutants, but the D1 protein was degraded more slowly than in wild-type, and mobilization of the PSII supercomplexes from the grana to the stromal lamellae for repair was also suppressed. In addition, higher accumulation of reactive oxygen species and preferential oxidation of PSII reaction center core proteins in thylakoid membranes were observed in the mutants during HL illumination. Taken together, our current data show that the absence of STN8 is sufficient to abolish PCPP in osstn8 mutants and to produce all of the phenotypes observed in the double mutant of Arabidopsis, indicating the essential role of STN8-mediated PCPP in PSII repair. PMID:24103067

  9. Adaptation.

    PubMed

    Broom, Donald M

    2006-01-01

    The term adaptation is used in biology in three different ways. It may refer to changes which occur at the cell and organ level, or at the individual level, or at the level of gene action and evolutionary processes. Adaptation by cells, especially nerve cells helps in: communication within the body, the distinguishing of stimuli, the avoidance of overload and the conservation of energy. The time course and complexity of these mechanisms varies. Adaptive characters of organisms, including adaptive behaviours, increase fitness so this adaptation is evolutionary. The major part of this paper concerns adaptation by individuals and its relationships to welfare. In complex animals, feed forward control is widely used. Individuals predict problems and adapt by acting before the environmental effect is substantial. Much of adaptation involves brain control and animals have a set of needs, located in the brain and acting largely via motivational mechanisms, to regulate life. Needs may be for resources but are also for actions and stimuli which are part of the mechanism which has evolved to obtain the resources. Hence pigs do not just need food but need to be able to carry out actions like rooting in earth or manipulating materials which are part of foraging behaviour. The welfare of an individual is its state as regards its attempts to cope with its environment. This state includes various adaptive mechanisms including feelings and those which cope with disease. The part of welfare which is concerned with coping with pathology is health. Disease, which implies some significant effect of pathology, always results in poor welfare. Welfare varies over a range from very good, when adaptation is effective and there are feelings of pleasure or contentment, to very poor. A key point concerning the concept of individual adaptation in relation to welfare is that welfare may be good or poor while adaptation is occurring. Some adaptation is very easy and energetically cheap and

  10. RNA interference targeting against S100A4 suppresses cell growth and motility and induces apoptosis in human pancreatic cancer cells

    SciTech Connect

    Tabata, Takahiro; Tsukamoto, Nobukazu; Fooladi, Abbas Ali Imani; Yamanaka, Sumitaka; Furukawa, Toru; Ishida, Masaharu; Sato, Daisuke; Gu, Zhaodi; Nagase, Hiroki; Egawa, Shinichi; Sunamura, Makoto; Horii, Akira

    2009-12-18

    S100A4 protein belongs to the S100 subfamily, which has grown to be one of the large subfamilies of the EF-hand Ca{sup 2+}-binding proteins, and overexpression of S100A4 is suggested to associate with cell proliferation, invasion, and metastasis. We observed frequent overexpression of S100A4 in pancreatic cancer cell lines and further analyzed RNAi-mediated knockdown to address the possibility of its use as a therapeutic target for pancreatic cancer. The specific knockdown of S100A4 strongly suppressed cell growth, induced G2 arrest and eventual apoptosis, and decreased cell migration. Furthermore, microarray analyses revealed that knockdown of S100A4 induced expression of the tumor suppressor genes PRDM2 and VASH1. Our present results suggest the possibility that the inhibition of S100A4 can be utilized in antitumor applications for patients with pancreatic cancer.

  11. Alpha-synuclein interferes with cAMP/PKA-dependent upregulation of dopamine β-hydroxylase and is associated with abnormal adaptive responses to immobilization stress.

    PubMed

    Kim, Sasuk; Park, Ji-Min; Moon, Jisook; Choi, Hyun Jin

    2014-02-01

    Parkinson's disease (PD) is clinically characterized not only by motor symptoms but also by non-motor symptoms, such as anxiety and mood changes. Based on our previous study showing that overexpression of wild-type or mutant α-synuclein (α-SYN) interferes with cAMP/PKA-dependent transcriptional activation in norepinephrine (NE)-producing cells, the effect of wild-type and mutant α-SYN on cAMP response element (CRE)-mediated regulation of the NE-synthesizing enzyme dopamine β-hydroxylase (DBH) was evaluated in this study. Overexpression of wild-type or mutant α-SYN interfered with CRE-mediated regulation of DBH transcription in NE-producing SK-N-BE(2) cells. Upon entering the nucleus, α-SYN interacted with the DBH promoter region encompassing the CRE, which interfered with forskolin-induced CREB binding to the CRE region. Interestingly, mutant A53T α-SYN showed much higher tendency to nuclear translocation and interaction with the DBH promoter region encompassing the CRE than wild type. In addition, A53T α-SYN expressing transgenic mice exhibited increased anxiety-like behaviors under normal conditions and abnormal regulation of DBH expression in response to immobilization stress with abnormal adaptive responses. These data provide an insight into the physiological function of α-SYN in NErgic neuronal cells, which further indicates that the α-SYN mutation may play a causative role in the generation of non-motor symptoms in PD. PMID:24252179

  12. The status of supergenes in the 21st century: recombination suppression in Batesian mimicry and sex chromosomes and other complex adaptations.

    PubMed

    Charlesworth, Deborah

    2016-01-01

    I review theoretical models for the evolution of supergenes in the cases of Batesian mimicry in butterflies, distylous plants and sex chromosomes. For each of these systems, I outline the genetic evidence that led to the proposal that they involve multiple genes that interact during 'complex adaptations', and at which the mutations involved are not unconditionally advantageous, but show advantages that trade-off against some disadvantages. I describe recent molecular genetic studies of these systems and questions they raise about the evolution of suppressed recombination. Nonrecombining regions of sex chromosomes have long been known, but it is not yet fully understood why recombination suppression repeatedly evolved in systems in distantly related taxa, but does not always evolve. Recent studies of distylous plants are tending to support the existence of recombination-suppressed genome regions, which may include modest numbers of genes and resemble recently evolved sex-linked regions. For Batesian mimicry, however, molecular genetic work in two butterfly species suggests a new supergene scenario, with a single gene mutating to produce initial adaptive phenotypes, perhaps followed by modifiers specifically refining and perfecting the new phenotype. PMID:27087840

  13. A dual-plate ITO-ITO generator-collector microtrench sensor: surface activation, spatial separation and suppression of irreversible oxygen and ascorbate interference.

    PubMed

    Hasnat, Mohammad A; Gross, Andrew J; Dale, Sara E C; Barnes, Edward O; Compton, Richard G; Marken, Frank

    2014-02-01

    Generator-collector electrode systems are based on two independent working electrodes with overlapping diffusion fields where chemically reversible redox processes (oxidation and reduction) are coupled to give amplified current signals. A generator-collector trench electrode system prepared from two tin-doped indium oxide (ITO) electrodes placed vis-à-vis with a 22 μm inter-electrode gap is employed here as a sensor in aqueous media. The reversible 2-electron anthraquinone-2-sulfonate redox system is demonstrated to give well-defined collector responses even in the presence of oxygen due to the irreversible nature of the oxygen reduction. For the oxidation of dopamine on ITO, novel "Piranha-activation" effects are observed and chemically reversible generator-collector feedback conditions are achieved at pH 7, by selecting a more negative collector potential, again eliminating possible oxygen interference. Finally, dopamine oxidation in the presence of ascorbate is demonstrated with the irreversible oxidation of ascorbate at the "mouth" of the trench electrode and chemically reversible oxidation of dopamine in the trench "interior". This spatial separation of chemically reversible and irreversible processes within and outside the trench is discussed as a potential in situ microscale sensing and separation tool. PMID:24317451

  14. Hypoxia-inducible enhancer/alpha-fetoprotein promoter-driven RNA interference targeting STK15 suppresses proliferation and induces apoptosis in human hepatocellular carcinoma cells.

    PubMed

    Gao, Ping; Wang, Rui; Shen, Jian-Jun; Lin, Fang; Wang, Xi; Dong, Ke; Zhang, Hui-Zhong

    2008-11-01

    STK15 (Aurora A/BTAK) is an oncogenic serine/threonine kinase that plays a role in centrosome separation and in the formation of the mitotic bipolar spindle. It is highly expressed and constitutively activated in various human tumors including hepatocellular carcinoma (HCC). To investigate its possibility as a molecular target for future therapies directed against hepatocellular carcinoma, we constructed a tissue-specific RNA interference (RNAi) system mediated by hypoxia-inducible (HI) enhancer/alpha-fetoprotein (AFP) promoter and employed it to downregulate exogenous reporters (LUC and EGFP) and endogenous STK15 gene expression and analyzed the phenotypical changes in HCC cells. Results showed that the expression of exogenous reporters (LUC and EGFP) was specifically downregulated in hepatoma cells but not in non-hepatoma cells. Moreover, the specific downregulation of STK15 expression in hepatocellular carcinoma cells (HepG2) significantly inhibited in vitro cellular proliferation and in vivo tumorigenicity. Furthermore, we also found that the downregulation of STK15 expression led to cell arrest in the G(2)/M phase and finally apoptosis induction of HepG2 cells. Thus, the HI enhancer/AFP promoter-mediated RNAi targeting STK15 may be a potential therapeutic strategy for the treatment of hepatocellular carcinoma with tumor specificity and high efficacy. PMID:18803637

  15. IETS and quantum interference: Propensity rules in the presence of an interference feature

    SciTech Connect

    Lykkebo, Jacob; Solomon, Gemma C.; Gagliardi, Alessio; Pecchia, Alessandro

    2014-09-28

    Destructive quantum interference in single molecule electronics is an intriguing phenomenon; however, distinguishing quantum interference effects from generically low transmission is not trivial. In this paper, we discuss how quantum interference effects in the transmission lead to either low current or a particular line shape in current-voltage curves, depending on the position of the interference feature. Second, we consider how inelastic electron tunneling spectroscopy can be used to probe the presence of an interference feature by identifying vibrational modes that are selectively suppressed when quantum interference effects dominate. That is, we expand the understanding of propensity rules in inelastic electron tunneling spectroscopy to molecules with destructive quantum interference.

  16. IETS and quantum interference: propensity rules in the presence of an interference feature.

    PubMed

    Lykkebo, Jacob; Gagliardi, Alessio; Pecchia, Alessandro; Solomon, Gemma C

    2014-09-28

    Destructive quantum interference in single molecule electronics is an intriguing phenomenon; however, distinguishing quantum interference effects from generically low transmission is not trivial. In this paper, we discuss how quantum interference effects in the transmission lead to either low current or a particular line shape in current-voltage curves, depending on the position of the interference feature. Second, we consider how inelastic electron tunneling spectroscopy can be used to probe the presence of an interference feature by identifying vibrational modes that are selectively suppressed when quantum interference effects dominate. That is, we expand the understanding of propensity rules in inelastic electron tunneling spectroscopy to molecules with destructive quantum interference. PMID:25273424

  17. In-Flight Suppression of an Unstable F/A-18 Structural Mode Using the Space Launch System Adaptive Augmenting Control System

    NASA Technical Reports Server (NTRS)

    VanZwieten, Tannen S.; Gilligan, Eric T.; Wall, John H.; Miller, Christopher J.; Hanson, Curtis E.; Orr, Jeb S.

    2015-01-01

    NASA's Space Launch System (SLS) Flight Control System (FCS) includes an Adaptive Augmenting Control (AAC) component which employs a multiplicative gain update law to enhance the performance and robustness of the baseline control system for extreme off-nominal scenarios. The SLS FCS algorithm including AAC has been flight tested utilizing a specially outfitted F/A-18 fighter jet in which the pitch axis control of the aircraft was performed by a Non-linear Dynamic Inversion (NDI) controller, SLS reference models, and the SLS flight software prototype. This paper describes test cases from the research flight campaign in which the fundamental F/A-18 airframe structural mode was identified using post-flight frequency-domain reconstruction, amplified to result in closed loop instability, and suppressed in-flight by the SLS adaptive control system.

  18. In-Flight Suppression of a Destabilized F/A-18 Structural Mode Using the Space Launch System Adaptive Augmenting Control System

    NASA Technical Reports Server (NTRS)

    Wall, John H.; VanZwieten, Tannen S.; Gilligan, Eric T.; Miller, Christopher J.; Hanson, Curtis E.; Orr, Jeb S.

    2015-01-01

    NASA's Space Launch System (SLS) Flight Control System (FCS) includes an Adaptive Augmenting Control (AAC) component which employs a multiplicative gain update law to enhance the performance and robustness of the baseline control system for extreme off nominal scenarios. The SLS FCS algorithm including AAC has been flight tested utilizing a specially outfitted F/A-18 fighter jet in which the pitch axis control of the aircraft was performed by a Non-linear Dynamic Inversion (NDI) controller, SLS reference models, and the SLS flight software prototype. This paper describes test cases from the research flight campaign in which the fundamental F/A-18 airframe structural mode was identified using frequency-domain reconstruction of flight data, amplified to result in closed loop instability, and suppressed in-flight by the SLS adaptive control system.

  19. Adapt

    NASA Astrophysics Data System (ADS)

    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

  20. Adaptive antenna arrays for satellite communication

    NASA Technical Reports Server (NTRS)

    Gupta, Inder J.

    1989-01-01

    The feasibility of using adaptive antenna arrays to provide interference protection in satellite communications was studied. The feedback loops as well as the sample matric inversion (SMI) algorithm for weight control were studied. Appropriate modifications in the two were made to achieve the required interference suppression. An experimental system was built to test the modified feedback loops and the modified SMI algorithm. The performance of the experimental system was evaluated using bench generated signals and signals received from TVRO geosynchronous satellites. A summary of results is given. Some suggestions for future work are also presented.

  1. Supersonic flutter suppression of electrorheological fluid-based adaptive panels resting on elastic foundations using sliding mode control

    NASA Astrophysics Data System (ADS)

    Hasheminejad, Seyyed M.; Nezami, M.; Aryaee Panah, M. E.

    2012-04-01

    Brief reviews on suppressing panel flutter vibrations by various active control strategies as well as utilization tunable electrorheological fluids (ERFs) for vibration control of structural systems are presented. Active suppression of the supersonic flutter motion of a simply supported sandwich panel with a tunable ERF interlayer, and coupled to an elastic foundation, is subsequently investigated. The structural formulation is based on the classical beam theory along with the Winkler-Pasternak foundation model, the ER fluid core is modeled as a first-order Kelvin-Voigt material, and the quasi-steady first-order supersonic piston theory is employed to describe the aerodynamic loading. Hamilton’s principle is used to derive a set of fully coupled dynamic equations of motion. The generalized Fourier expansions in conjunction with the Galerkin method are then employed to formulate the governing equations in the state space domain. The critical dynamic pressures at which unstable panel oscillations (coalescence of eigenvalues) occur are obtained via the p-method for selected applied electric field strengths (E = 0,2,4 kV mm-1). The classical Runge-Kutta time integration algorithm is subsequently used to calculate the open-loop aeroelastic response of the system in various basic loading configurations (i.e. uniformly distributed blast, gust, sonic boom, and step loads), with or without an interacting soft/stiff elastic foundation. Finally, a sliding mode control synthesis (SMC) involving the first six natural modes of the structural system is set up to actively suppress the closed-loop system response in supersonic flight conditions and under the imposed excitations. Simulation results demonstrate performance, effectiveness, and insensitivity with respect to the spillover of the proposed SMC-based control system. Limiting cases are considered and good agreements with the data available in the literature as well as with the computations made by using the Rayleigh

  2. Industrial interference and radio astronomy

    NASA Astrophysics Data System (ADS)

    Jessner, A.

    2013-07-01

    The interferer - victim scenario is described for the case of industrial interference affecting radio astronomical observatories. The sensitivity of radio astronomical receivers and their interference limits are outlined. EMC above 30 MHz is a serious problem for Radio Astronomy. Interferer (CISPR) and victim (ITU-R RA 769) standards are not harmonised. The emissions from the interferer and their spectral characteristics are not defined sufficiently well by CISPR standards. The required minimum coupling losses (MCL) between an industrial device and radio astronomical antenna depends on device properties but is shown to exceed 140 dB in most cases. Spatial separation of a few km is insufficient on its own, the terrain must shield > 30-40 dB, additional mitigations such as extra shielding or suppression of high frequency emissions may be necessary. A case by case compatibility analysis and tailored EMC measures are required for individual installations. Aggregation of many weak rfi emitters can become serious problem. If deployment densities are high enough, the emission constraints can even exceed those for a single interferer at a short distance from the radio observatory. Compatibility studies must account not only for the single interferer but also for many widely distributed interference sources.

  3. Type I Interferon Induced Epigenetic Regulation of Macrophages Suppresses Innate and Adaptive Immunity in Acute Respiratory Viral Infection

    PubMed Central

    Kroetz, Danielle N.; Allen, Ronald M.; Schaller, Matthew A.; Cavallaro, Cleyton; Ito, Toshihiro; Kunkel, Steven L.

    2015-01-01

    Influenza A virus (IAV) is an airborne pathogen that causes significant morbidity and mortality each year. Macrophages (Mϕ) are the first immune population to encounter IAV virions in the lungs and are required to control infection. In the present study, we explored the mechanism by which cytokine signaling regulates the phenotype and function of Mϕ via epigenetic modification of chromatin. We have found that type I interferon (IFN-I) potently upregulates the lysine methyltransferase Setdb2 in murine and human Mϕ, and in turn Setdb2 regulates Mϕ-mediated immunity in response to IAV. The induction of Setdb2 by IFN-I was significantly impaired upon inhibition of the JAK-STAT signaling cascade, and chromatin immunoprecipitation revealed that both STAT1 and interferon regulatory factor 7 bind upstream of the transcription start site to induce expression. The generation of Setdb2LacZ reporter mice revealed that IAV infection results in systemic upregulation of Setdb2 in myeloid cells. In the lungs, alveolar Mϕ expressed the highest level of Setdb2, with greater than 70% lacZ positive on day 4 post-infection. Silencing Setdb2 activity in Mϕ in vivo enhanced survival in lethal IAV infection. Enhanced host protection correlated with an amplified antiviral response and less obstruction to the airways. By tri-methylating H3K9, Setdb2 silenced the transcription of Mx1 and Isg15, antiviral effectors that inhibit IAV replication. Accordingly, a reduced viral load in knockout mice on day 8 post-infection was linked to elevated Isg15 and Mx1 transcript in the lungs. In addition, Setdb2 suppressed the expression of a large number of other genes with proinflammatory or immunomodulatory function. This included Ccl2, a chemokine that signals through CCR2 to regulate monocyte recruitment to infectious sites. Consistently, knockout mice produced more CCL2 upon IAV infection and this correlated with a 2-fold increase in the number of inflammatory monocytes and alveolar Mϕ in the

  4. Type I Interferon Induced Epigenetic Regulation of Macrophages Suppresses Innate and Adaptive Immunity in Acute Respiratory Viral Infection.

    PubMed

    Kroetz, Danielle N; Allen, Ronald M; Schaller, Matthew A; Cavallaro, Cleyton; Ito, Toshihiro; Kunkel, Steven L

    2015-12-01

    Influenza A virus (IAV) is an airborne pathogen that causes significant morbidity and mortality each year. Macrophages (Mϕ) are the first immune population to encounter IAV virions in the lungs and are required to control infection. In the present study, we explored the mechanism by which cytokine signaling regulates the phenotype and function of Mϕ via epigenetic modification of chromatin. We have found that type I interferon (IFN-I) potently upregulates the lysine methyltransferase Setdb2 in murine and human Mϕ, and in turn Setdb2 regulates Mϕ-mediated immunity in response to IAV. The induction of Setdb2 by IFN-I was significantly impaired upon inhibition of the JAK-STAT signaling cascade, and chromatin immunoprecipitation revealed that both STAT1 and interferon regulatory factor 7 bind upstream of the transcription start site to induce expression. The generation of Setdb2LacZ reporter mice revealed that IAV infection results in systemic upregulation of Setdb2 in myeloid cells. In the lungs, alveolar Mϕ expressed the highest level of Setdb2, with greater than 70% lacZ positive on day 4 post-infection. Silencing Setdb2 activity in Mϕ in vivo enhanced survival in lethal IAV infection. Enhanced host protection correlated with an amplified antiviral response and less obstruction to the airways. By tri-methylating H3K9, Setdb2 silenced the transcription of Mx1 and Isg15, antiviral effectors that inhibit IAV replication. Accordingly, a reduced viral load in knockout mice on day 8 post-infection was linked to elevated Isg15 and Mx1 transcript in the lungs. In addition, Setdb2 suppressed the expression of a large number of other genes with proinflammatory or immunomodulatory function. This included Ccl2, a chemokine that signals through CCR2 to regulate monocyte recruitment to infectious sites. Consistently, knockout mice produced more CCL2 upon IAV infection and this correlated with a 2-fold increase in the number of inflammatory monocytes and alveolar Mϕ in the

  5. Adaptive Multi-Layer LMS Controller Design and Application to Active Vibration Suppression on a Truss and Proposed Impact Analysis Technique

    NASA Technical Reports Server (NTRS)

    Barney, Timothy A.; Shin, Y. S.; Agrawal, B. N.

    2001-01-01

    This research develops an adaptive controller that actively suppresses a single frequency disturbance source at a remote position and tests the system on the NPS Space Truss. The experimental results are then compared to those predicted by an ANSYS finite element model. The NPS space truss is a 3.7-meter long truss that simulates a space-borne appendage with sensitive equipment mounted at its extremities. One of two installed piezoelectric actuators and an Adaptive Multi-Layer LMS control law were used to effectively eliminate an axial component of the vibrations induced by a linear proof mass actuator mounted at one end of the truss. Experimental and analytical results both demonstrate reductions to the level of system noise. Vibration reductions in excess of 50dB were obtained through experimentation and over 100dB using ANSYS, demonstrating the ability to model this system with a finite element model. This report also proposes a method to use distributed quartz accelerometers to evaluate the location, direction, and energy of impacts on the NPS space truss using the dSPACE data acquisition and processing system to capture the structural response and compare it to known reference Signals.

  6. Higher-order ambulatory electrocardiogram identification and motion artifact suppression with adaptive second- and third-order Volterra filters

    NASA Astrophysics Data System (ADS)

    Sabry-Rizk, Madiha; Zgallai, Walid; El-Khafif, Sahar; Carson, Ewart; Grattan, Kenneth T. V.

    1998-10-01

    The objective of this paper is to demonstrate how, in a few seconds, a relatively simple ECG monitor, PC and advanced signal processing algorithms could pinpoint microvolts - late potentials - result from an infarct zone in the heart and is used as an indicator in identifying patients prone to ventricular tachycardia which, if left untreated, leads to ventricular fibrillation. We will characterize recorded ECG data obtained from the standard three vector electrodes during exercise in terms of their higher-order statistical features. Essentially we use adaptive LMS- and Kalman-based second- and third-order Volterra filters to model the non- linear low-frequency P and T waves and motion artifacts which might overlap with the QRS complex and lead to false positive QRS detection. We will illustrate the effectiveness of this new approach by mapping out bispectral regions with a strong bicoherence manifestation and showing their corresponding temporal/spatial origins. Furthermore, we will present a few examples of our own application of these non-invasive techniques to illustrate what we see as their promise for analysis of heart abnormality.

  7. Thiol dependent NF-κB suppression and inhibition of T-cell mediated adaptive immune responses by a naturally occurring steroidal lactone Withaferin A.

    PubMed

    Gambhir, Lokesh; Checker, Rahul; Sharma, Deepak; Thoh, M; Patil, Anand; Degani, M; Gota, Vikram; Sandur, Santosh K

    2015-12-01

    Withaferin A (WA), a steroidal lactone isolated from ayurvedic medicinal plant Withania somnifera, was shown to inhibit tumor growth by inducing oxidative stress and suppressing NF-κB pathway. However, its effect on T-cell mediated adaptive immune responses and the underlying mechanism has not been investigated. Since both T-cell responses and NF-κB pathway are known to be redox sensitive, the present study was undertaken to elucidate the effect of WA on adaptive immune responses in vitro and in vivo. WA inhibited mitogen induced T-cell and B-cell proliferation in vitro without inducing any cell death. It inhibited upregulation of T-cell (CD25, CD69, CD71 and CD54) and B-cell (CD80, CD86 and MHC-II) activation markers and secretion of Th1 and Th2 cytokines. WA induced oxidative stress by increasing the basal ROS levels and the immunosuppressive effects of WA were abrogated only by thiol anti-oxidants. The redox modulatory effects of WA in T-cells were attributed to its ability to directly interact with free thiols. WA inhibited NF-κB nuclear translocation in lymphocytes and prevented the direct binding of nuclear NF-κB to its consensus sequence. MALDI-TOF analysis using a synthetic NF-κB-p50 peptide containing Cys-62 residue suggested that WA can modify the cysteine residue of NF-κB. The pharmacokinetic studies for WA were also carried out and in vivo efficacy of WA was studied using mouse model of Graft-versus-host disease. In conclusion, WA is a potent inhibitor of T-cell responses and acts via a novel thiol dependent mechanism and inhibition of NF-κB pathway. PMID:26408225

  8. Inhibition of Translation Initiation by Protein 169: A Vaccinia Virus Strategy to Suppress Innate and Adaptive Immunity and Alter Virus Virulence

    PubMed Central

    Strnadova, Pavla; Ren, Hongwei; Valentine, Robert; Mazzon, Michela; Sweeney, Trevor R.; Brierley, Ian; Smith, Geoffrey L.

    2015-01-01

    Vaccinia virus (VACV) is the prototypic orthopoxvirus and the vaccine used to eradicate smallpox. Here we show that VACV strain Western Reserve protein 169 is a cytoplasmic polypeptide expressed early during infection that is excluded from virus factories and inhibits the initiation of cap-dependent and cap-independent translation. Ectopic expression of protein 169 causes the accumulation of 80S ribosomes, a reduction of polysomes, and inhibition of protein expression deriving from activation of multiple innate immune signaling pathways. A virus lacking 169 (vΔ169) replicates and spreads normally in cell culture but is more virulent than parental and revertant control viruses in intranasal and intradermal murine models of infection. Intranasal infection by vΔ169 caused increased pro-inflammatory cytokines and chemokines, infiltration of pulmonary leukocytes, and lung weight. These alterations in innate immunity resulted in a stronger CD8+ T-cell memory response and better protection against virus challenge. This work illustrates how inhibition of host protein synthesis can be a strategy for virus suppression of innate and adaptive immunity. PMID:26334635

  9. Inhibition of Translation Initiation by Protein 169: A Vaccinia Virus Strategy to Suppress Innate and Adaptive Immunity and Alter Virus Virulence.

    PubMed

    Strnadova, Pavla; Ren, Hongwei; Valentine, Robert; Mazzon, Michela; Sweeney, Trevor R; Brierley, Ian; Smith, Geoffrey L

    2015-09-01

    Vaccinia virus (VACV) is the prototypic orthopoxvirus and the vaccine used to eradicate smallpox. Here we show that VACV strain Western Reserve protein 169 is a cytoplasmic polypeptide expressed early during infection that is excluded from virus factories and inhibits the initiation of cap-dependent and cap-independent translation. Ectopic expression of protein 169 causes the accumulation of 80S ribosomes, a reduction of polysomes, and inhibition of protein expression deriving from activation of multiple innate immune signaling pathways. A virus lacking 169 (vΔ169) replicates and spreads normally in cell culture but is more virulent than parental and revertant control viruses in intranasal and intradermal murine models of infection. Intranasal infection by vΔ169 caused increased pro-inflammatory cytokines and chemokines, infiltration of pulmonary leukocytes, and lung weight. These alterations in innate immunity resulted in a stronger CD8+ T-cell memory response and better protection against virus challenge. This work illustrates how inhibition of host protein synthesis can be a strategy for virus suppression of innate and adaptive immunity. PMID:26334635

  10. Herschel's Interference Demonstration.

    ERIC Educational Resources Information Center

    Perkalskis, Benjamin S.; Freeman, J. Reuben

    2000-01-01

    Describes Herschel's demonstration of interference arising from many coherent rays. Presents a method for students to reproduce this demonstration and obtain beautiful multiple-beam interference patterns. (CCM)

  11. The Cas6e ribonuclease is not required for interference and adaptation by the E. coli type I-E CRISPR-Cas system

    PubMed Central

    Semenova, Ekaterina; Kuznedelov, Konstantin; Datsenko, Kirill A.; Boudry, Pierre M.; Savitskaya, Ekaterina E.; Medvedeva, Sofia; Beloglazova, Natalia; Logacheva, Maria; Yakunin, Alexander F.; Severinov, Konstantin

    2015-01-01

    CRISPR-Cas are small RNA-based adaptive prokaryotic immunity systems protecting cells from foreign DNA or RNA. Type I CRISPR-Cas systems are composed of a multiprotein complex (Cascade) that, when bound to CRISPR RNA (crRNA), can recognize double-stranded DNA targets and recruit the Cas3 nuclease to destroy target-containing DNA. In the Escherichia coli type I-E CRISPR-Cas system, crRNAs are generated upon transcription of CRISPR arrays consisting of multiple palindromic repeats and intervening spacers through the function of Cas6e endoribonuclease, which cleaves at specific positions of repeat sequences of the CRISPR array transcript. Cas6e is also a component of Cascade. Here, we show that when mature unit-sized crRNAs are provided in a Cas6e-independent manner by transcription termination, the CRISPR-Cas system can function without Cas6e. The results should allow facile interrogation of various targets by type I-E CRISPR-Cas system in E. coli using unit-sized crRNAs generated by transcription. PMID:26013814

  12. Motion compensation for adaptive horizontal line array processing

    NASA Astrophysics Data System (ADS)

    Yang, T. C.

    2003-01-01

    Large aperture horizontal line arrays have small resolution cells and can be used to separate a target signal from an interference signal by array beamforming. High-resolution adaptive array processing can be used to place a null at the interference signal so that the array gain can be much higher than that of conventional beamforming. But these nice features are significantly degraded by the source motion, which reduces the time period under which the environment can be considered stationary from the array processing point of view. For adaptive array processing, a large number of data samples are generally required to minimize the variance of the cross-spectral density, or the covariance matrix, between the array elements. For a moving source and interference, the penalty of integrating over a large number of samples is the spread of signal and interference energy to more than one or two eigenvalues. The signal and interference are no longer clearly identified by the eigenvectors and, consequently, the ability to suppress the interference suffers. We show in this paper that the effect of source motion can be compensated for the (signal) beam covariance matrix, thus allowing integration over a large number of data samples without loss in the signal beam power. We employ an equivalent of a rotating coordinate frame to track the signal bearing change and use the waveguide invariant theory to compensate the signal range change by frequency shifting.

  13. A Robust Approach For Acoustic Noise Suppression In Speech Using ANFIS

    NASA Astrophysics Data System (ADS)

    Martinek, Radek; Kelnar, Michal; Vanus, Jan; Bilik, Petr; Zidek, Jan

    2015-11-01

    The authors of this article deals with the implementation of a combination of techniques of the fuzzy system and artificial intelligence in the application area of non-linear noise and interference suppression. This structure used is called an Adaptive Neuro Fuzzy Inference System (ANFIS). This system finds practical use mainly in audio telephone (mobile) communication in a noisy environment (transport, production halls, sports matches, etc). Experimental methods based on the two-input adaptive noise cancellation concept was clearly outlined. Within the experiments carried out, the authors created, based on the ANFIS structure, a comprehensive system for adaptive suppression of unwanted background interference that occurs in audio communication and degrades the audio signal. The system designed has been tested on real voice signals. This article presents the investigation and comparison amongst three distinct approaches to noise cancellation in speech; they are LMS (least mean squares) and RLS (recursive least squares) adaptive filtering and ANFIS. A careful review of literatures indicated the importance of non-linear adaptive algorithms over linear ones in noise cancellation. It was concluded that the ANFIS approach had the overall best performance as it efficiently cancelled noise even in highly noise-degraded speech. Results were drawn from the successful experimentation, subjective-based tests were used to analyse their comparative performance while objective tests were used to validate them. Implementation of algorithms was experimentally carried out in Matlab to justify the claims and determine their relative performances.

  14. Neurogenesis-mediated forgetting minimizes proactive interference

    PubMed Central

    Epp, Jonathan R.; Silva Mera, Rudy; Köhler, Stefan; Josselyn, Sheena A.; Frankland, Paul W.

    2016-01-01

    Established memories may interfere with the encoding of new memories, particularly when existing and new memories overlap in content. By manipulating levels of hippocampal neurogenesis, here we show that neurogenesis regulates this form of proactive interference. Increasing hippocampal neurogenesis weakens existing memories and, in doing so, facilitates the encoding of new, conflicting (but not non-conflicting) information in mice. Conversely, decreasing neurogenesis stabilizes existing memories, and impedes the encoding of new, conflicting information. These results suggest that reduced proactive interference is an adaptive benefit of neurogenesis-induced forgetting. PMID:26917323

  15. Software Reduces Radio-Interference Effects in Radar Data

    NASA Technical Reports Server (NTRS)

    Le, Charles T-C; Hensley, Scott; Chapin, Elaine

    2004-01-01

    A computer program suppresses the effects of narrow-band radio-frequency interference (RFI) on the data collected by a wide-band radar system. The need for this program arises because some advanced wide-band synthetic-aperture radar systems utilize frequency bands that include frequencies used by other radio services. In this program, the RFI environment is represented by an auto-regressive process, the frequency band of which is narrow relative to that of the radar. Most of the RFI signals, both narrow- and wide-band, are estimated in one pass of a least-mean-square (LMS) adaptive filter. The program implements three popular LMS algorithms: the time-domain LMS, the frequency-domain LMS, and the filter-bank LMS adaptive-filter algorithms. The program can be run in a manual or automatic mode. In the manual mode, the user selects the filter parameters prior to execution. In the automatic mode, the program utilizes median-filter and spectral-estimation techniques plus the variable-step-size LMS algorithm for automatic determination of filter parameters, and the parameters are adaptively changed as functions of the inputs, resulting in better overall performance.

  16. Signal interference RF photonic bandstop filter.

    PubMed

    Aryanfar, Iman; Choudhary, Amol; Shahnia, Shayan; Pagani, Mattia; Liu, Yang; Marpaung, David; Eggleton, Benjamin J

    2016-06-27

    In the microwave domain, signal interference bandstop filters with high extinction and wide stopbands are achieved through destructive interference of two signals. Implementation of this filtering concept using RF photonics will lead to unique filters with high performance, enhanced tuning range and reconfigurability. Here we demonstrate an RF photonic signal interference filter, achieved through the combination of precise synthesis of stimulated Brillouin scattering (SBS) loss with advanced phase and amplitude tailoring of RF modulation sidebands. We achieve a square-shaped, 20-dB extinction RF photonic filter over a tunable bandwidth of up to 1 GHz with a central frequency tuning range of 16 GHz using a low SBS loss of ~3 dB. Wideband destructive interference in this novel filter leads to the decoupling of the filter suppression from its bandwidth and shape factor. This allows the creation of a filter with all-optimized qualities. PMID:27410650

  17. Furospinosulin-1, Marine Spongean Furanosesterterpene, Suppresses the Growth of Hypoxia-Adapted Cancer Cells by Binding to Transcriptional Regulators p54(nrb) and LEDGF/p75.

    PubMed

    Arai, Masayoshi; Kawachi, Takashi; Kotoku, Naoyuki; Nakata, Chiaki; Kamada, Haruhiko; Tsunoda, Shin-ichi; Tsutsumi, Yasuo; Endo, Hiroko; Inoue, Masahiro; Sato, Hiroki; Kobayashi, Motomasa

    2016-01-01

    Hypoxia-adapted cancer cells in tumors contribute to the pathological progression of cancer. Cancer research has therefore focused on the identification of molecules responsible for hypoxia adaptation in cancer cells, as well as the development of new compounds with action against hypoxia-adapted cancer cells. The marine natural product furospinosulin-1 (1) has displayed hypoxia-selective growth inhibition against cultured cancer cells, and has shown in vivo anti-tumor activity, although its precise mode of action and molecular targets remain unclear. In this study, we found that 1 is selectively effective against hypoxic regions of tumors, and that it directly binds to the transcriptional regulators p54(nrb) and LEDGF/p75, which have not been previously identified as mediators of hypoxia adaptation in cancer cells. PMID:26561285

  18. Knockdown of mTOR by lentivirus‑mediated RNA interference suppresses atherosclerosis and stabilizes plaques via a decrease of macrophages by autophagy in apolipoprotein E‑deficient mice.

    PubMed

    Wang, Xiaochuang; Li, Lingxia; Li, Manxiang; Dang, Xiaoyan; Wan, Lin; Wang, Ni; Bi, Xiaoju; Gu, Changwei; Qiu, Suijuan; Niu, Xiaolin; Zhu, Xinye; Wang, Lina

    2013-11-01

    Atherosclerotic plaque destabilization and rupture leads to acute coronary syndromes which cause serious damage to human health worldwide. However, there is currently a lack of efficient therapeutic methods. Mammalian target of rapamycin (mTOR) has been suggested to be involved in the development of atherosclerotic plaques and serves as a therapeutic target. The present study was performed to determine whether RNA interference (RNAi) of mTOR in vivo by LV‑mediated small hairpin RNA (shRNA) was capable of inhibiting the progression of atherosclerotic plaques. LV‑mediated shRNA against mTOR (LV‑shmTOR) was designed and obtained. Male apolipoprotein E‑deficient mice were fed a high‑fat diet and a constrictive collar was placed around the right carotid arteries of these mice to induce plaque formation. Eight weeks after surgery, mice were randomly divided into the mTOR RNA interference (LV‑shmTOR) group, receiving treatment with LV‑mTOR‑shRNA; the LV‑shCON group, receiving treatment with LV‑non‑specific‑shRNA; and the control group, receiving treatment with phosphate‑buffered saline. Following transfection, the mice were sacrificed to evaluate the effects of mTOR expression silencing on atherosclerosis. Transfection of LV‑mTOR‑shRNA markedly inhibited the mRNA and protein expression levels. Knockdown of mTOR ameliorated dysregulated blood lipid metabolism and stabilized aortic atherosclerotic plaques by decreasing the plaque area and increasing the fibrous cap and cap‑to‑core ratio. Furthermore, macrophages were decreased by silencing mTOR in atherosclerotic plaques. In addition, western blot analysis revealed that the knockdown of mTOR increased autophagy‑related protein 13 (Atg13) dephosphorylation and light chain 3‑I/light chain 3‑II (LC3‑I/LC3‑II) ratios, both of which were associated with a high activity of autophagy, suggesting an increase of autophagy in atherosclerotic plaques. Moreover, genes including matrix

  19. In-Flight Suppression of a De-Stabilized F/A-18 Structural Mode Using the Space Launch System Adaptive Augmenting Control System

    NASA Technical Reports Server (NTRS)

    Wall, John; VanZwieten, Tannen; Giiligan Eric; Miller, Chris; Hanson, Curtis; Orr, Jeb

    2015-01-01

    Adaptive Augmenting Control (AAC) has been developed for NASA's Space Launch System (SLS) family of launch vehicles and implemented as a baseline part of its flight control system (FCS). To raise the technical readiness level of the SLS AAC algorithm, the Launch Vehicle Adaptive Control (LVAC) flight test program was conducted in which the SLS FCS prototype software was employed to control the pitch axis of Dryden's specially outfitted F/A-18, the Full Scale Advanced Systems Test Bed (FAST). This presentation focuses on a set of special test cases which demonstrate the successful mitigation of the unstable coupling of an F/A-18 airframe structural mode with the SLS FCS.

  20. Silencing of hypoxia inducible factor-1α by RNA interference inhibits growth of SK-NEP-1 Wilms tumour cells in vitro, and suppresses tumourigenesis and angiogenesis in vivo.

    PubMed

    Shi, Bo; Li, Ying; Wang, Xiuli; Yang, Yi; Li, Dan; Liu, Xin; Yang, Xianghong

    2016-06-01

    Wilms tumour is the most common tumour of the pediatric kidney. Elevation of hypoxia-inducible factor 1α (HIF-1α) has been detected in 93% to 100% of human Wilms tumour specimens, suggesting a potential value of HIF-1α as a therapeutic target for Wilms tumour. In the present study, a stable HIF-1α-silenced Wilms tumour cell strain was established by introducing HIF-1α short-hairpin RNA (shRNA) into SK-NEP-1 cells. Silencing of HIF-1α significantly reduced single-cell growth capacity, suppressed proliferation and arrested cell cycle of SK-NEP-1 cells. In addition, reduction of HIF-1α expression induced apoptosis in SK-NEP-1 cells, which was accompanied by increased levels of cleaved caspase-3, cleaved poly (ADP-ribose) polymerase (PARP) and Bax as well as downregulation of Bcl-2 in the cells. Furthermore, when inoculated subcutaneously in nude mice, HIF-1α-silenced SK-NEP-1 cells displayed retarded tumour growth and impaired tumour angiogenesis. In summary, the findings of this study suggest that HIF-1α plays a critical role in the development of Wilms tumour, and it may serve as a candidate target of gene therapy for Wilms tumour. PMID:27015631

  1. Analysis of modified SMI method for adaptive array weight control

    NASA Technical Reports Server (NTRS)

    Dilsavor, R. L.; Moses, R. L.

    1989-01-01

    An adaptive array is applied to the problem of receiving a desired signal in the presence of weak interference signals which need to be suppressed. A modification, suggested by Gupta, of the sample matrix inversion (SMI) algorithm controls the array weights. In the modified SMI algorithm, interference suppression is increased by subtracting a fraction F of the noise power from the diagonal elements of the estimated covariance matrix. Given the true covariance matrix and the desired signal direction, the modified algorithm is shown to maximize a well-defined, intuitive output power ratio criterion. Expressions are derived for the expected value and variance of the array weights and output powers as a function of the fraction F and the number of snapshots used in the covariance matrix estimate. These expressions are compared with computer simulation and good agreement is found. A trade-off is found to exist between the desired level of interference suppression and the number of snapshots required in order to achieve that level with some certainty. The removal of noise eigenvectors from the covariance matrix inverse is also discussed with respect to this application. Finally, the type and severity of errors which occur in the covariance matrix estimate are characterized through simulation.

  2. The right posterior paravermis and the control of language interference

    PubMed Central

    Filippi, Roberto; Richardson, Fiona M.; Dick, Frederic; Leech, Robert; Green, David W.; Thomas, Michael S.C.; Price, Cathy J.

    2011-01-01

    Auditory and written language in humans' comprehension necessitates attention to the message of interest and suppression of interference from distracting sources. Investigating the brain areas associated with the control of interference is challenging because it is inevitable that activation of the brain regions that control interference co-occurs with activation related to interference per se. To isolate the mechanisms that control verbal interference, we used a combination of structural and functional imaging techniques in Italian and German participants who spoke English as a second language. First, we searched structural MRI images of Italian participants for brain regions where brain structure correlated with the ability to suppress interference from the unattended dominant language (Italian) while processing heard sentences in their weaker language (English). This revealed an area in the posterior paravermis of the right cerebellum where grey matter density was higher in individuals who were better at controlling verbal interference. Second, we found functional activation in the same region when our German participants made semantic decisions on written English words in the presence of interference from unrelated words in their dominant language (German). This combination of structural and functional imaging therefore highlights the contribution of the right posterior paravermis to the control of verbal interference. We suggest that the importance of this region for language processing has previously been missed because most fMRI studies limit the field of view to increase sensitivity; with the lower part of the cerebellum being the most likely region to be excluded. PMID:21775616

  3. Thick Film Interference.

    ERIC Educational Resources Information Center

    Trefil, James

    1983-01-01

    Discusses why interference effects cannot be seen with a thick film, starting with a review of the origin of interference patterns in thin films. Considers properties of materials in films, properties of the light source, and the nature of light. (JN)

  4. Prolonged inorganic arsenite exposure suppresses insulin-stimulated AKT S473 phosphorylation and glucose uptake in 3T3-L1 adipocytes: Involvement of the adaptive antioxidant response

    SciTech Connect

    Xue, Peng; Hou, Yongyong; Zhang, Qiang; Woods, Courtney G.; Yarborough, Kathy; Liu, Huiyu; Sun, Guifan; Andersen, Melvin E.; Pi, Jingbo

    2011-04-08

    Highlights: {yields} In 3T3-L1 adipocytes iAs{sup 3+} decreases insulin-stimulated glucose uptake. {yields} iAs{sup 3+} attenuates insulin-induced phosphorylation of AKT S473. {yields} iAs{sup 3+} activates the cellular adaptive oxidative stress response. {yields} iAs{sup 3+} impairs insulin-stimulated ROS signaling. {yields} iAs{sup 3+} decreases expression of adipogenic genes and GLUT4. -- Abstract: There is growing evidence that chronic exposure of humans to inorganic arsenic, a potent environmental oxidative stressor, is associated with the incidence of type 2 diabetes (T2D). One critical feature of T2D is insulin resistance in peripheral tissues, especially in mature adipocytes, the hallmark of which is decreased insulin-stimulated glucose uptake (ISGU). Despite the deleterious effects of reactive oxygen species (ROS), they have been recognized as a second messenger serving an intracellular signaling role for insulin action. Nuclear factor erythroid 2-related factor 2 (NRF2) is a central transcription factor regulating cellular adaptive response to oxidative stress. This study proposes that in response to arsenic exposure, the NRF2-mediated adaptive induction of endogenous antioxidant enzymes blunts insulin-stimulated ROS signaling and thus impairs ISGU. Exposure of differentiated 3T3-L1 cells to low-level (up to 2 {mu}M) inorganic arsenite (iAs{sup 3+}) led to decreased ISGU in a dose- and time-dependent manner. Concomitant to the impairment of ISGU, iAs{sup 3+} exposure significantly attenuated insulin-stimulated intracellular ROS accumulation and AKT S473 phosphorylation, which could be attributed to the activation of NRF2 and induction of a battery of endogenous antioxidant enzymes. In addition, prolonged iAs{sup 3+} exposure of 3T3-L1 adipocytes resulted in significant induction of inflammatory response genes and decreased expression of adipogenic genes and glucose transporter type 4 (GLUT4), suggesting chronic inflammation and reduction in GLUT4

  5. The proposed role of suppression in simultaneous interpretation

    PubMed Central

    Gernsbacher, Morton Ann; Shlesinger, Miriam

    2014-01-01

    In this paper we suggest that the cognitive mechanism of suppression attenuates interference in many language comprehension phenomena, and is particularly crucial when comprehension must share processing capacity with other cognitive tasks, as is manifestly the case in simultaneous interpreting. During lexical access, the mechanism of suppression attenuates the interference caused by the activation of other lexical information, such as the inappropriate meanings of homonyms. During anaphoric reference, the mechanism of suppression attenuates the interference caused by the activation of other potential referents. In this way, the referent to which the anaphor does refer becomes the most activated concept. During syntactic parsing, the mechanism of suppression attenuates the interference caused by a previous syntactic form. During metaphor comprehension, the mechanism of suppression attenuates the interference caused by a literal interpretation. During inferencing, the mechanism of suppression attenuates the interference caused by an initial but inappropriate inference. We propose therefore that suppression — a general, cognitive mechanism that attenuates interference — plays a crucial role in language comprehension and simultaneous interpretation. PMID:25520570

  6. Interference and Polarized Light.

    ERIC Educational Resources Information Center

    Charas, Seymour

    1988-01-01

    Discusses a demonstration of interference phenomena using three sheets of polaroid material, a light source, and a light meter. Describes instructional procedures with mathematical expressions and a diagram. (YP)

  7. Suppression effects on musical and verbal memory.

    PubMed

    Schendel, Zachary A; Palmer, Caroline

    2007-06-01

    Three experiments contrasted the effects of articulatory suppression on recognition memory for musical and verbal sequences. In Experiment 1, a standard/comparison task was employed, with digit or note sequences presented visually or auditorily while participants remained silent or produced intermittent verbal suppression (saying "the") or musical suppression (singing "la"). Both suppression types decreased performance by equivalent amounts, as compared with no suppression. Recognition accuracy was lower during suppression for visually presented digits than during that for auditorily presented digits (consistent with phonological loop predictions), whereas accuracy was equivalent for visually presented notes and auditory tones. When visual interference filled the retention interval in Experiment 2, performance with visually presented notes but not digits was impaired. Experiment 3 forced participants to translate visually presented music sequences by presenting comparison sequences auditorily. Suppression effects for visually presented music resembled those for digits only when the recognition task required sensory translation of cues. PMID:17848022

  8. Out-of-band and adjacent-channel interference reduction by analog nonlinear filters

    NASA Astrophysics Data System (ADS)

    Nikitin, Alexei V.; Davidchack, Ruslan L.; Smith, Jeffrey E.

    2015-12-01

    In a perfect world, we would have `brick wall' filters, no-distortion amplifiers and mixers, and well-coordinated spectrum operations. The real world, however, is prone to various types of unintentional and intentional interference of technogenic (man-made) origin that can disrupt critical communication systems. In this paper, we introduce a methodology for mitigating technogenic interference in communication channels by analog nonlinear filters, with an emphasis on the mitigation of out-of-band and adjacent-channel interference. Interference induced in a communications receiver by external transmitters can be viewed as wide-band non-Gaussian noise affecting a narrower-band signal of interest. This noise may contain a strong component within the receiver passband, which may dominate over the thermal noise. While the total wide-band interference seen by the receiver may or may not be impulsive, we demonstrate that the interfering component due to power emitted by the transmitter into the receiver channel is likely to appear impulsive under a wide range of conditions. We give an example of mechanisms of impulsive interference in digital communication systems resulting from the nonsmooth nature of any physically realizable modulation scheme for transmission of a digital (discontinuous) message. We show that impulsive interference can be effectively mitigated by nonlinear differential limiters (NDLs). An NDL can be configured to behave linearly when the input signal does not contain outliers. When outliers are encountered, the nonlinear response of the NDL limits the magnitude of the respective outliers in the output signal. The signal quality is improved in excess of that achievable by the respective linear filter, increasing the capacity of a communications channel. The behavior of an NDL, and its degree of nonlinearity, is controlled by a single parameter in a manner that enables significantly better overall suppression of the noise-containing impulsive components

  9. Analysis of Modified SMI Method for Adaptive Array Weight Control. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Dilsavor, Ronald Louis

    1989-01-01

    An adaptive array is used to receive a desired signal in the presence of weak interference signals which need to be suppressed. A modified sample matrix inversion (SMI) algorithm controls the array weights. The modification leads to increased interference suppression by subtracting a fraction of the noise power from the diagonal elements of the covariance matrix. The modified algorithm maximizes an intuitive power ratio criterion. The expected values and variances of the array weights, output powers, and power ratios as functions of the fraction and the number of snapshots are found and compared to computer simulation and real experimental array performance. Reduced-rank covariance approximations and errors in the estimated covariance are also described.

  10. Space-time adaptive decision feedback neural receivers with data selection for high-data-rate users in DS-CDMA systems.

    PubMed

    de Lamare, Rodrigo C; Sampaio-Neto, Raimundo

    2008-11-01

    A space-time adaptive decision feedback (DF) receiver using recurrent neural networks (RNNs) is proposed for joint equalization and interference suppression in direct-sequence code-division multiple-access (DS-CDMA) systems equipped with antenna arrays. The proposed receiver structure employs dynamically driven RNNs in the feedforward section for equalization and multiaccess interference (MAI) suppression and a finite impulse response (FIR) linear filter in the feedback section for performing interference cancellation. A data selective gradient algorithm, based upon the set-membership (SM) design framework, is proposed for the estimation of the coefficients of RNN structures and is applied to the estimation of the parameters of the proposed neural receiver structure. Simulation results show that the proposed techniques achieve significant performance gains over existing schemes. PMID:18990643

  11. Optical interference fringe reduction in frequency-modulation spectroscopy experiments

    NASA Astrophysics Data System (ADS)

    Hjelme, Dag Roar; Neegard, Steinar; Vartdal, Erling

    1995-08-01

    We show both theoretically and experimentally that interference fringe signals can always be suppressed to improve the signal-to-noise ratio, provided that the modulation frequency is of the order of the absorption linewidth or higher. Suppression of optical interference fringes by more than 1 order of magnitude and signal-to-noise ratio enhancement of more than 13 dB is demonstrated by use of a proper choice of laser modulation frequency. A further fringe reduction of 10 dB is possible by adjustment of the local oscillator phase.

  12. Subspace based adaptive denoising of surface EMG from neurological injury patients

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Ying, Dongwen; Zev Rymer, William; Zhou, Ping

    2014-10-01

    Objective: After neurological injuries such as spinal cord injury, voluntary surface electromyogram (EMG) signals recorded from affected muscles are often corrupted by interferences, such as spurious involuntary spikes and background noises produced by physiological and extrinsic/accidental origins, imposing difficulties for signal processing. Conventional methods did not well address the problem caused by interferences. It is difficult to mitigate such interferences using conventional methods. The aim of this study was to develop a subspace-based denoising method to suppress involuntary background spikes contaminating voluntary surface EMG recordings. Approach: The Karhunen-Loeve transform was utilized to decompose a noisy signal into a signal subspace and a noise subspace. An optimal estimate of EMG signal is derived from the signal subspace and the noise power. Specifically, this estimator is capable of making a tradeoff between interference reduction and signal distortion. Since the estimator partially relies on the estimate of noise power, an adaptive method was presented to sequentially track the variation of interference power. The proposed method was evaluated using both semi-synthetic and real surface EMG signals. Main results: The experiments confirmed that the proposed method can effectively suppress interferences while keep the distortion of voluntary EMG signal in a low level. The proposed method can greatly facilitate further signal processing, such as onset detection of voluntary muscle activity. Significance: The proposed method can provide a powerful tool for suppressing background spikes and noise contaminating voluntary surface EMG signals of paretic muscles after neurological injuries, which is of great importance for their multi-purpose applications.

  13. Suppression of radio frequency inteference (RFI) for synchronous impulse reconstruction ultra-wideband radar

    NASA Astrophysics Data System (ADS)

    Nguyen, Lam; Soumekh, Mehrdad

    2005-05-01

    This paper is concerned with the issues associated with the suppression of radio frequency interference (RFI) for a synchronous impulse reconstruction (SIRE) ultra-wideband (UWB) synthetic aperture radar (SAR) that is currently being designed and built at the Army Research Laboratory. In this effort, we are developing the next version of the UWB radar that can employ inexpensive A/D converters to digitize wideband signals using the equivalent time sampling technique. In this presentation, we provide an analytical model for the signature of the RFI sources that are measured via an equivalent time sampling scheme. This formulation reveals spectral as well as temporal properties of the measured RFI signals that would aid a user in developing sniff (passive) data collection strategies for constructing adaptive digital signal processing methods for suppressing RFI sources.

  14. CRISPR interference and priming varies with individual spacer sequences

    PubMed Central

    Xue, Chaoyou; Seetharam, Arun S.; Musharova, Olga; Severinov, Konstantin; J. Brouns, Stan J.; Severin, Andrew J.; Sashital, Dipali G.

    2015-01-01

    CRISPR–Cas (clustered regularly interspaced short palindromic repeats-CRISPR associated) systems allow bacteria to adapt to infection by acquiring ‘spacer’ sequences from invader DNA into genomic CRISPR loci. Cas proteins use RNAs derived from these loci to target cognate sequences for destruction through CRISPR interference. Mutations in the protospacer adjacent motif (PAM) and seed regions block interference but promote rapid ‘primed’ adaptation. Here, we use multiple spacer sequences to reexamine the PAM and seed sequence requirements for interference and priming in the Escherichia coli Type I-E CRISPR–Cas system. Surprisingly, CRISPR interference is far more tolerant of mutations in the seed and the PAM than previously reported, and this mutational tolerance, as well as priming activity, is highly dependent on spacer sequence. We identify a large number of functional PAMs that can promote interference, priming or both activities, depending on the associated spacer sequence. Functional PAMs are preferentially acquired during unprimed ‘naïve’ adaptation, leading to a rapid priming response following infection. Our results provide numerous insights into the importance of both spacer and target sequences for interference and priming, and reveal that priming is a major pathway for adaptation during initial infection. PMID:26586800

  15. Interference between conscious and unconscious facial expression information.

    PubMed

    Ye, Xing; He, Sheng; Hu, Ying; Yu, Yong Qiang; Wang, Kai

    2014-01-01

    There is ample evidence to show that many types of visual information, including emotional information, could be processed in the absence of visual awareness. For example, it has been shown that masked subliminal facial expressions can induce priming and adaptation effects. However, stimulus made invisible in different ways could be processed to different extent and have differential effects. In this study, we adopted a flanker type behavioral method to investigate whether a flanker rendered invisible through Continuous Flash Suppression (CFS) could induce a congruency effect on the discrimination of a visible target. Specifically, during the experiment, participants judged the expression (either happy or fearful) of a visible face in the presence of a nearby invisible face (with happy or fearful expression). Results show that participants were slower and less accurate in discriminating the expression of the visible face when the expression of the invisible flanker face was incongruent. Thus, facial expression information rendered invisible with CFS and presented a different spatial location could enhance or interfere with consciously processed facial expression information. PMID:25162153

  16. Quantum interference in polyenes

    SciTech Connect

    Tsuji, Yuta; Hoffmann, Roald; Movassagh, Ramis; Datta, Supriyo

    2014-12-14

    The explicit form of the zeroth Green's function in the Hückel model, approximated by the negative of the inverse of the Hückel matrix, has direct quantum interference consequences for molecular conductance. We derive a set of rules for transmission between two electrodes attached to a polyene, when the molecule is extended by an even number of carbons at either end (transmission unchanged) or by an odd number of carbons at both ends (transmission turned on or annihilated). These prescriptions for the occurrence of quantum interference lead to an unexpected consequence for switches which realize such extension through electrocyclic reactions: for some specific attachment modes the chemically closed ring will be the ON position of the switch. Normally the signs of the entries of the Green's function matrix are assumed to have no physical significance; however, we show that the signs may have observable consequences. In particular, in the case of multiple probe attachments – if coherence in probe connections can be arranged – in some cases new destructive interference results, while in others one may have constructive interference. One such case may already exist in the literature.

  17. N450 as a candidate neural marker for interference control deficits in children with learning disabilities.

    PubMed

    Liu, Chunlei; Yao, Ru; Wang, Zuowei; Zhou, Renlai

    2014-07-01

    A deficit in the ability to suppress irrelevant or interfering stimuli may account for a variety of dysfunctional behaviors in children with learning disabilities (LD). However, neural correlates underlying this deficit in interference control in the LD are still unknown. In this study, we recruited a group of children with LD (age: 10.78 ± 0.52) along with an age-matched control group (age: 10.74 ± 0.86) and asked them to perform a numerical Stroop task. During the task, we used electroencephalogram (EEG) to record their event-related potentials (ERPs). We further evaluated performance of these children on a battery of tests, including the Academic Adaptability Test (AAT), an adapted Chinese version of Pupil Rating Scale (PRS), and Raven's Standard Progressive Matrices (SPM). Children's scores on recent math and Chinese exams were also obtained. Results showed that: 1) children with LD had worse performance in the incongruent condition of the numerical Stroop task suggesting that children with LD had interference control deficits but not basic numerical cognition; 2) children with LD had larger N450 effects on the frontal and posterior sites, but did not show any difference in early ERP components, suggesting that the behavioral difference was related with interference control rather than early visual perception processing; and 3) N450 effects were correlated with accuracy in the numerical Stroop task, performance in Raven's SPM, as well as school math performance. These results suggest that N450 can serve as a potential electrophysiology marker for identifying and potentially, providing targeted intervention for children with LD. PMID:24858538

  18. Adaptive Arrays for Weak Interfering Signals: An Experimental System. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Ward, James

    1987-01-01

    An experimental adaptive antenna system was implemented to study the performance of adaptive arrays in the presence of weak interfering signals. It is a sidelobe canceler with two auxiliary elements. Modified feedback loops, which decorrelate the noise components of the two inputs to the loop correlators, control the array weights. Digital processing is used for algorithm implementation and performance evaluation. The results show that the system can suppress interfering signals which are 0 to 10 dB below the thermal noise level in the main channel by 20 to 30 dB. When the desired signal is strong in the auxiliary elements the amount of interference suppression decreases. The amount of degradation depends on the number of interfering signals incident on the communication system. A modified steering vector which overcomes this problem is proposed.

  19. Canada thistle (Cirsium arvense) suppession by sudangrass interference and defoliation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Canada thistle is difficult to manage in farming systems with reduced reliance on herbicides, including organic and low-external input systems. Previous field studies found that defoliation or sudangrass interference suppressed Canada thistle. Our objective was to understand the factors causing supp...

  20. Identifying separate components of surround suppression

    PubMed Central

    Schallmo, Michael-Paul; Murray, Scott O.

    2016-01-01

    Surround suppression is a well-known phenomenon in which the response to a visual stimulus is diminished by the presence of neighboring stimuli. This effect is observed in neural responses in areas such as primary visual cortex, and also manifests in visual contrast perception. Studies in animal models have identified at least two separate mechanisms that may contribute to surround suppression: one that is monocular and resistant to contrast adaptation, and another that is binocular and strongly diminished by adaptation. The current study was designed to investigate whether these two mechanisms exist in humans and if they can be identified psychophysically using eye-of-origin and contrast adaptation manipulations. In addition, we examined the prediction that the monocular suppression component is broadly tuned for orientation, while suppression between eyes is narrowly tuned. Our results confirmed that when center and surrounding stimuli were presented dichoptically (in opposite eyes), suppression was orientation-tuned. Following adaptation in the surrounding region, no dichoptic suppression was observed, and monoptic suppression no longer showed orientation selectivity. These results are consistent with a model of surround suppression that depends on both low-level and higher level components. This work provides a method to assess the separate contributions of these components during spatial context processing in human vision. PMID:26756172

  1. The Role of the Left Head of Caudate in Suppressing Irrelevant Words

    ERIC Educational Resources Information Center

    Ali, Nilufa; Green, David W.; Kherif, Ferath; Devlin, Joseph T.; Price, Cathy J.

    2010-01-01

    Suppressing irrelevant words is essential to successful speech production and is expected to involve general control mechanisms that reduce interference from task-unrelated processing. To investigate the neural mechanisms that suppress visual word interference, we used fMRI and a Stroop task, using a block design with an event-related analysis.…

  2. Parasitic interference in nulling interferometry

    NASA Astrophysics Data System (ADS)

    Matter, A.; Defrère, D.; Danchi, W. C.; Lopez, B.; Absil, O.

    2013-05-01

    Nulling interferometry aims to detect faint objects close to bright stars. Its principle is to produce a destructive interference along the line of sight so that the stellar flux is rejected, while the flux of the off-axis source can be transmitted. In practice, various instrumental perturbations can degrade the nulling performance. Any imperfection in phase, amplitude or polarization produces a spurious flux that leaks to the interferometer output and corrupts the transmitted off-axis flux. One of these instrumental perturbations is the crosstalk phenomenon, which occurs because of multiple parasitic reflections inside transmitting optics, and/or diffraction effects related to beam propagation along finite size optics. It can include a crosstalk of a beam with itself, and a mutual crosstalk between different beams. This can create a parasitic interference pattern, which degrades the intrinsic transmission map - or intensity response - of the interferometer. In this context, we describe how this instrumental effect impairs the performance of a Bracewell interferometer. A simple formalism is developed to derive the corresponding modified intensity response of the interferometer, as a function of the two parameters of interest: the crosstalk level (or contamination rate) and the phase shift between the primary and secondary - parasitic - beams. We then apply our mathematical approach to a few scientific cases, both analytically and using the GENIESIM simulation software, adapted to handle coherent crosstalk. Our results show that a coherent crosstalk level of about 1 per cent implies a 20 per cent drop of the signal-to-noise ratio at most. Careful attention should thus be paid to reduce the crosstalk level inside an interferometric instrument and ensure an instrumental stability that provides the necessary sensitivity through calibration procedures.

  3. Tilt aftereffect following adaptation to translational Glass patterns

    PubMed Central

    Pavan, Andrea; Hocketstaller, Johanna; Contillo, Adriano; Greenlee, Mark W.

    2016-01-01

    Glass patterns (GPs) consist of randomly distributed dot pairs (dipoles) whose orientations are determined by specific geometric transforms. We assessed whether adaptation to stationary oriented translational GPs suppresses the activity of orientation selective detectors producing a tilt aftereffect (TAE). The results showed that adaptation to GPs produces a TAE similar to that reported in previous studies, though reduced in amplitude. This suggests the involvement of orientation selective mechanisms. We also measured the interocular transfer (IOT) of the GP-induced TAE and found an almost complete IOT, indicating the involvement of orientation selective and binocularly driven units. In additional experiments, we assessed the role of attention in TAE from GPs. The results showed that distraction during adaptation similarly modulates the TAE after adapting to both GPs and gratings. Moreover, in the case of GPs, distraction is likely to interfere with the adaptation process rather than with the spatial summation of local dipoles. We conclude that TAE from GPs possibly relies on visual processing levels in which the global orientation of GPs has been encoded by neurons that are mostly binocularly driven, orientation selective and whose adaptation-related neural activity is strongly modulated by attention. PMID:27005949

  4. Tilt aftereffect following adaptation to translational Glass patterns.

    PubMed

    Pavan, Andrea; Hocketstaller, Johanna; Contillo, Adriano; Greenlee, Mark W

    2016-01-01

    Glass patterns (GPs) consist of randomly distributed dot pairs (dipoles) whose orientations are determined by specific geometric transforms. We assessed whether adaptation to stationary oriented translational GPs suppresses the activity of orientation selective detectors producing a tilt aftereffect (TAE). The results showed that adaptation to GPs produces a TAE similar to that reported in previous studies, though reduced in amplitude. This suggests the involvement of orientation selective mechanisms. We also measured the interocular transfer (IOT) of the GP-induced TAE and found an almost complete IOT, indicating the involvement of orientation selective and binocularly driven units. In additional experiments, we assessed the role of attention in TAE from GPs. The results showed that distraction during adaptation similarly modulates the TAE after adapting to both GPs and gratings. Moreover, in the case of GPs, distraction is likely to interfere with the adaptation process rather than with the spatial summation of local dipoles. We conclude that TAE from GPs possibly relies on visual processing levels in which the global orientation of GPs has been encoded by neurons that are mostly binocularly driven, orientation selective and whose adaptation-related neural activity is strongly modulated by attention. PMID:27005949

  5. Language control in bilinguals: The adaptive control hypothesis

    PubMed Central

    Abutalebi, Jubin

    2013-01-01

    Speech comprehension and production are governed by control processes. We explore their nature and dynamics in bilingual speakers with a focus on speech production. Prior research indicates that individuals increase cognitive control in order to achieve a desired goal. In the adaptive control hypothesis we propose a stronger hypothesis: Language control processes themselves adapt to the recurrent demands placed on them by the interactional context. Adapting a control process means changing a parameter or parameters about the way it works (its neural capacity or efficiency) or the way it works in concert, or in cascade, with other control processes (e.g., its connectedness). We distinguish eight control processes (goal maintenance, conflict monitoring, interference suppression, salient cue detection, selective response inhibition, task disengagement, task engagement, opportunistic planning). We consider the demands on these processes imposed by three interactional contexts (single language, dual language, and dense code-switching). We predict adaptive changes in the neural regions and circuits associated with specific control processes. A dual-language context, for example, is predicted to lead to the adaptation of a circuit mediating a cascade of control processes that circumvents a control dilemma. Effective test of the adaptive control hypothesis requires behavioural and neuroimaging work that assesses language control in a range of tasks within the same individual. PMID:25077013

  6. Language control in bilinguals: The adaptive control hypothesis.

    PubMed

    Green, David W; Abutalebi, Jubin

    2013-08-01

    Speech comprehension and production are governed by control processes. We explore their nature and dynamics in bilingual speakers with a focus on speech production. Prior research indicates that individuals increase cognitive control in order to achieve a desired goal. In the adaptive control hypothesis we propose a stronger hypothesis: Language control processes themselves adapt to the recurrent demands placed on them by the interactional context. Adapting a control process means changing a parameter or parameters about the way it works (its neural capacity or efficiency) or the way it works in concert, or in cascade, with other control processes (e.g., its connectedness). We distinguish eight control processes (goal maintenance, conflict monitoring, interference suppression, salient cue detection, selective response inhibition, task disengagement, task engagement, opportunistic planning). We consider the demands on these processes imposed by three interactional contexts (single language, dual language, and dense code-switching). We predict adaptive changes in the neural regions and circuits associated with specific control processes. A dual-language context, for example, is predicted to lead to the adaptation of a circuit mediating a cascade of control processes that circumvents a control dilemma. Effective test of the adaptive control hypothesis requires behavioural and neuroimaging work that assesses language control in a range of tasks within the same individual. PMID:25077013

  7. Differential interference contrast tomography.

    PubMed

    Vishnyakov, Gennady; Levin, Gennady; Minaev, Vladimir; Latushko, Mikhail; Nekrasov, Nikolay; Pickalov, Valery

    2016-07-01

    We present a new approach to optical tomography of phase objects that is referred to as differential interference contrast tomography (DICT). The main feature of DICT is that the result of tomographic reconstruction is a 3D DIC image. This image is described by partial derivative of 3D refractive index distribution in one direction. The DICT setup consists of a lateral shearing phase-shifting interference microscope with low-coherent LED illumination. To create projections of the sample at various illumination angles, an angular scanning beam was used. 3D DIC tomograms of a white blood cell are presented. The comparison between the reconstructed DIC tomogram slices and the conventional DIC images of the same sample at the same depths are also represented. PMID:27367095

  8. Exploiting Genetic Interference for Antiviral Therapy.

    PubMed

    Tanner, Elizabeth J; Kirkegaard, Karla A; Weinberger, Leor S

    2016-05-01

    Rapidly evolving viruses are a major threat to human health. Such viruses are often highly pathogenic (e.g., influenza virus, HIV, Ebola virus) and routinely circumvent therapeutic intervention through mutational escape. Error-prone genome replication generates heterogeneous viral populations that rapidly adapt to new selection pressures, leading to resistance that emerges with treatment. However, population heterogeneity bears a cost: when multiple viral variants replicate within a cell, they can potentially interfere with each other, lowering viral fitness. This genetic interference can be exploited for antiviral strategies, either by taking advantage of a virus's inherent genetic diversity or through generating de novo interference by engineering a competing genome. Here, we discuss two such antiviral strategies, dominant drug targeting and therapeutic interfering particles. Both strategies harness the power of genetic interference to surmount two particularly vexing obstacles-the evolution of drug resistance and targeting therapy to high-risk populations-both of which impede treatment in resource-poor settings. PMID:27149616

  9. Exploiting Genetic Interference for Antiviral Therapy

    PubMed Central

    Kirkegaard, Karla A.; Weinberger, Leor S.

    2016-01-01

    Rapidly evolving viruses are a major threat to human health. Such viruses are often highly pathogenic (e.g., influenza virus, HIV, Ebola virus) and routinely circumvent therapeutic intervention through mutational escape. Error-prone genome replication generates heterogeneous viral populations that rapidly adapt to new selection pressures, leading to resistance that emerges with treatment. However, population heterogeneity bears a cost: when multiple viral variants replicate within a cell, they can potentially interfere with each other, lowering viral fitness. This genetic interference can be exploited for antiviral strategies, either by taking advantage of a virus’s inherent genetic diversity or through generating de novo interference by engineering a competing genome. Here, we discuss two such antiviral strategies, dominant drug targeting and therapeutic interfering particles. Both strategies harness the power of genetic interference to surmount two particularly vexing obstacles—the evolution of drug resistance and targeting therapy to high-risk populations—both of which impede treatment in resource-poor settings. PMID:27149616

  10. Wind Tunnel Wall Interference Assessment and Correction, 1983

    NASA Technical Reports Server (NTRS)

    Newman, P. A. (Editor); Barnwell, R. W. (Editor)

    1984-01-01

    Technical information focused upon emerging wall interference assessment/correction (WIAC) techniques applicable to transonic wind tunnels with conventional and passively or partially adapted walls is given. The possibility of improving the assessment and correction of data taken in conventional transonic wind tunnels by utilizing simultaneously obtained flow field data (generally taken near the walls) appears to offer a larger, nearer-term payoff than the fully adaptive wall concept. Development of WIAC procedures continues, and aspects related to validating the concept need to be addressed. Thus, the scope of wall interference topics discussed was somewhat limited.

  11. Interference competition and species coexistence.

    PubMed Central

    Amarasekare, Priyanga

    2002-01-01

    Interference competition is ubiquitous in nature. Yet its effects on resource exploitation remain largely unexplored for species that compete for dynamic resources. Here, I present a model of exploitative and interference competition with explicit resource dynamics. The model incorporates both biotic and abiotic resources. It considers interference competition both in the classical sense (i.e. each species suffers a net reduction in per capita growth rate via interference from, and interference on, the other species) and in the broad sense (i.e. each species suffers a net reduction in per capita growth rate via interference from, but can experience an increase in growth rate via interference on, the other species). Coexistence cannot occur under classical interference competition even when the species inferior at resource exploitation is superior at interference. Such a trade-off can, however, change the mechanism of competitive exclusion from dominance by the superior resource exploiter to a priority effect. Now the inferior resource exploiter can exclude the superior resource exploiter provided it has a higher initial abundance. By contrast, when interference is beneficial to the interacting species, coexistence is possible via a trade-off between exploitation and interference. These results hold regardless of whether the resource is biotic or abiotic, indicating that the outcome of exploitative and interference competition does not depend on the exact nature of resource dynamics. The model makes two key predictions. First, species that engage in costly interference mechanisms (e.g. territoriality, overgrowth or undercutting, allelopathy and other forms of chemical competition) should not be able to coexist unless they also engage in beneficial interference mechanisms (e.g. predation or parasitism). Second, exotic invasive species that displace native biota should be superior resource exploiters that have strong interference effects on native species with little

  12. Groups of bats improve sonar efficiency through mutual suppression of pulse emissions.

    PubMed

    Jarvis, Jenna; Jackson, William; Smotherman, Michael

    2013-01-01

    How bats adapt their sonar behavior to accommodate the noisiness of a crowded day roost is a mystery. Some bats change their pulse acoustics to enhance the distinction between theirs and another bat's echoes, but additional mechanisms are needed to explain the bat sonar system's exceptional resilience to jamming by conspecifics. Variable pulse repetition rate strategies offer one potential solution to this dynamic problem, but precisely how changes in pulse rate could improve sonar performance in social settings is unclear. Here we show that bats decrease their emission rates as population density increases, following a pattern that reflects a cumulative mutual suppression of each other's pulse emissions. Playback of artificially-generated echolocation pulses similarly slowed emission rates, demonstrating that suppression was mediated by hearing the pulses of other bats. Slower emission rates did not support an antiphonal emission strategy but did reduce the relative proportion of emitted pulses that overlapped with another bat's emissions, reducing the relative rate of mutual interference. The prevalence of acoustic interferences occurring amongst bats was empirically determined to be a linear function of population density and mean emission rates. Consequently as group size increased, small reductions in emission rates spread across the group partially mitigated the increase in interference rate. Drawing on lessons learned from communications networking theory we show how modest decreases in pulse emission rates can significantly increase the net information throughput of the shared acoustic space, thereby improving sonar efficiency for all individuals in a group. We propose that an automated acoustic suppression of pulse emissions triggered by bats hearing each other's emissions dynamically optimizes sonar efficiency for the entire group. PMID:23781208

  13. Groups of bats improve sonar efficiency through mutual suppression of pulse emissions

    PubMed Central

    Jarvis, Jenna; Jackson, William; Smotherman, Michael

    2013-01-01

    How bats adapt their sonar behavior to accommodate the noisiness of a crowded day roost is a mystery. Some bats change their pulse acoustics to enhance the distinction between theirs and another bat's echoes, but additional mechanisms are needed to explain the bat sonar system's exceptional resilience to jamming by conspecifics. Variable pulse repetition rate strategies offer one potential solution to this dynamic problem, but precisely how changes in pulse rate could improve sonar performance in social settings is unclear. Here we show that bats decrease their emission rates as population density increases, following a pattern that reflects a cumulative mutual suppression of each other's pulse emissions. Playback of artificially-generated echolocation pulses similarly slowed emission rates, demonstrating that suppression was mediated by hearing the pulses of other bats. Slower emission rates did not support an antiphonal emission strategy but did reduce the relative proportion of emitted pulses that overlapped with another bat's emissions, reducing the relative rate of mutual interference. The prevalence of acoustic interferences occurring amongst bats was empirically determined to be a linear function of population density and mean emission rates. Consequently as group size increased, small reductions in emission rates spread across the group partially mitigated the increase in interference rate. Drawing on lessons learned from communications networking theory we show how modest decreases in pulse emission rates can significantly increase the net information throughput of the shared acoustic space, thereby improving sonar efficiency for all individuals in a group. We propose that an automated acoustic suppression of pulse emissions triggered by bats hearing each other's emissions dynamically optimizes sonar efficiency for the entire group. PMID:23781208

  14. Sensors Locate Radio Interference

    NASA Technical Reports Server (NTRS)

    2009-01-01

    After receiving a NASA Small Business Innovation Research (SBIR) contract from Kennedy Space Center, Soneticom Inc., based in West Melbourne, Florida, created algorithms for time difference of arrival and radio interferometry, which it used in its Lynx Location System (LLS) to locate electromagnetic interference that can disrupt radio communications. Soneticom is collaborating with the Federal Aviation Administration (FAA) to install and test the LLS at its field test center in New Jersey in preparation for deploying the LLS at commercial airports. The software collects data from each sensor in order to compute the location of the interfering emitter.

  15. Adaptive Structures Flight Experiments

    NASA Technical Reports Server (NTRS)

    Martin, Maurice

    1992-01-01

    The topics are presented in viewgraph form and include the following: adaptive structures flight experiments; enhanced resolution using active vibration suppression; Advanced Controls Technology Experiment (ACTEX); ACTEX program status; ACTEX-2; ACTEX-2 program status; modular control patch; STRV-1b Cryocooler Vibration Suppression Experiment; STRV-1b program status; Precision Optical Bench Experiment (PROBE); Clementine Spacecraft Configuration; TECHSAT all-composite spacecraft; Inexpensive Structures and Materials Flight Experiment (INFLEX); and INFLEX program status.

  16. Adaptive structures flight experiments

    NASA Astrophysics Data System (ADS)

    Martin, Maurice

    The topics are presented in viewgraph form and include the following: adaptive structures flight experiments; enhanced resolution using active vibration suppression; Advanced Controls Technology Experiment (ACTEX); ACTEX program status; ACTEX-2; ACTEX-2 program status; modular control patch; STRV-1b Cryocooler Vibration Suppression Experiment; STRV-1b program status; Precision Optical Bench Experiment (PROBE); Clementine Spacecraft Configuration; TECHSAT all-composite spacecraft; Inexpensive Structures and Materials Flight Experiment (INFLEX); and INFLEX program status.

  17. Electromagnetic Interference on Pacemakers

    PubMed Central

    Erdogan, Okan

    2002-01-01

    External sources, either within or outside the hospital environment, may interfere with the appropriate function of pacemakers which are being implanted all around the world in current medical practice. The patient and the physician who is responsible for follow-up of the pacing systems may be confronted with some specific problems regarding the various types of electromagnetic interference (EMI). To avoid these unwanted EMI effects one must be aware of this potential problem and need to take some precautions. The effects of EMI on pacemaker function and precautions to overcome some specific problems were discussed in this review article. There are many sources of EMI interacting with pacemakers. Magnetic resonance imaging creates real problem and should be avoided in pacemaker patients. Cellular phones might be responsible for EMI when they were held on the same side with the pacemaker. Otherwise they don't cause any specific type of interaction with pacemakers. Sale security systems are not a problem if one walks through it without lingering in or near it. Patients having unipolar pacemaker systems are prone to develop EMI because of pectoral muscle artifacts during vigorous active physical exercise. PMID:17006562

  18. GNSS space-time interference mitigation and attitude determination in the presence of interference signals.

    PubMed

    Daneshmand, Saeed; Jahromi, Ali Jafarnia; Broumandan, Ali; Lachapelle, Gérard

    2015-01-01

    The use of Space-Time Processing (STP) in Global Navigation Satellite System (GNSS) applications is gaining significant attention due to its effectiveness for both narrowband and wideband interference suppression. However, the resulting distortion and bias on the cross correlation functions due to space-time filtering is a major limitation of this technique. Employing the steering vector of the GNSS signals in the filter structure can significantly reduce the distortion on cross correlation functions and lead to more accurate pseudorange measurements. This paper proposes a two-stage interference mitigation approach in which the first stage estimates an interference-free subspace before the acquisition and tracking phases and projects all received signals into this subspace. The next stage estimates array attitude parameters based on detecting and employing GNSS signals that are less distorted due to the projection process. Attitude parameters enable the receiver to estimate the steering vector of each satellite signal and use it in the novel distortionless STP filter to significantly reduce distortion and maximize Signal-to-Noise Ratio (SNR). GPS signals were collected using a six-element antenna array under open sky conditions to first calibrate the antenna array. Simulated interfering signals were then added to the digitized samples in software to verify the applicability of the proposed receiver structure and assess its performance for several interference scenarios. PMID:26016909

  19. GNSS Space-Time Interference Mitigation and Attitude Determination in the Presence of Interference Signals

    PubMed Central

    Daneshmand, Saeed; Jahromi, Ali Jafarnia; Broumandan, Ali; Lachapelle, Gérard

    2015-01-01

    The use of Space-Time Processing (STP) in Global Navigation Satellite System (GNSS) applications is gaining significant attention due to its effectiveness for both narrowband and wideband interference suppression. However, the resulting distortion and bias on the cross correlation functions due to space-time filtering is a major limitation of this technique. Employing the steering vector of the GNSS signals in the filter structure can significantly reduce the distortion on cross correlation functions and lead to more accurate pseudorange measurements. This paper proposes a two-stage interference mitigation approach in which the first stage estimates an interference-free subspace before the acquisition and tracking phases and projects all received signals into this subspace. The next stage estimates array attitude parameters based on detecting and employing GNSS signals that are less distorted due to the projection process. Attitude parameters enable the receiver to estimate the steering vector of each satellite signal and use it in the novel distortionless STP filter to significantly reduce distortion and maximize Signal-to-Noise Ratio (SNR). GPS signals were collected using a six-element antenna array under open sky conditions to first calibrate the antenna array. Simulated interfering signals were then added to the digitized samples in software to verify the applicability of the proposed receiver structure and assess its performance for several interference scenarios. PMID:26016909

  20. Flexible beam control using an adaptive truss

    NASA Technical Reports Server (NTRS)

    Warrington, Thomas J.; Horner, C. Garnett

    1990-01-01

    To demonstrate the feasibility of adaptive trusses for vibration suppression, a 12-ft-long beam is attached to a single cell of an adaptive truss which has three active battens. With the base of the adaptive truss attached to the laboratory frame, the measured strain of the vibrating beam shows the adaptive truss to be very effective in suppressing vibration when subjected to initial conditions. Control is accomplished by a PC/XT computer that implements an LQR-designed control law.

  1. Beamforming design with proactive interference cancelation in MISO interference channels

    NASA Astrophysics Data System (ADS)

    Li, Yang; Tian, Yafei; Yang, Chenyang

    2015-12-01

    In this paper, we design coordinated beamforming at base stations (BSs) to facilitate interference cancelation at users in interference networks, where each BS is equipped with multiple antennas and each user is with a single antenna. By assuming that each user can select the best decoding strategy to mitigate the interference, either canceling the interference after decoding when it is strong or treating it as noise when it is weak, we optimize the beamforming vectors that maximize the sum rate for the networks under different interference scenarios and find the solutions of beamforming with closed-form expressions. The inherent design principles are then analyzed, and the performance gain over passive interference cancelation is demonstrated through simulations in heterogeneous cellular networks.

  2. Total rod ERG suppression with high dose compassionate Fenretinide usage.

    PubMed

    Marmor, Michael F; Jain, Atul; Moshfeghi, Darius

    2008-11-01

    Fenretinide is a synthetic retinoid that interferes with the attachment of retinol to retinol binding protein. It may inhibit accumulation of A2E and lipofuscin, and is proposed as therapy for Stargardt disease. It is currently used for cancer therapy, and mild depression of rod function and dark adaptation is a side effect at standard dosage. We studied two youngsters (aged between 12 and 13) receiving high doses as compassionate treatment for neuroblastoma: 800 mg daily for 1 out of every 3 weeks, for roughly 2 years. Goldmann-Weekers dark adaptometry, ISCEV standard ERG and mfERG were performed, and blood was analyzed for vitamin A. Neither child complained of night blindness or showed retinal fundus abnormalities. On initial exam, dark adaptation thresholds were elevated by 3 log units, and there were no detectable rod ERG responses. However, cone responses and mfERG were normal. Retesting one subject 3 months after stopping the drug revealed normal rod thresholds (slightly delayed) and low normal rod ERG responses. Serum vitamin A levels were normal from both subjects, but there is no record of whether the samples were drawn during cycles on or off drug. Our study demonstrates that high dose Fenretinide can suppress rod function quite completely, although serum vitamin A and rod function apparently return to normal or near normal levels rapidly once the drug is stopped. It is intriguing that cone function and access to vitamin A seems largely independent of Fenretinide effects on retinol availability. PMID:18523815

  3. Graphene quantum interference photodetector

    PubMed Central

    Voss, Paul L

    2015-01-01

    Summary In this work, a graphene quantum interference (QI) photodetector was simulated in two regimes of operation. The structure consists of a graphene nanoribbon, Mach–Zehnder interferometer (MZI), which exhibits a strongly resonant transmission of electrons of specific energies. In the first regime of operation (that of a linear photodetector), low intensity light couples two resonant energy levels, resulting in scattering and differential transmission of current with an external quantum efficiency of up to 5.2%. In the second regime of operation, full current switching is caused by the phase decoherence of the current due to a strong photon flux in one or both of the interferometer arms in the same MZI structure. Graphene QI photodetectors have several distinct advantages: they are of very small size, they do not require p- and n-doped regions, and they exhibit a high external quantum efficiency. PMID:25821713

  4. Single-plasmon interferences.

    PubMed

    Dheur, Marie-Christine; Devaux, Eloïse; Ebbesen, Thomas W; Baron, Alexandre; Rodier, Jean-Claude; Hugonin, Jean-Paul; Lalanne, Philippe; Greffet, Jean-Jacques; Messin, Gaétan; Marquier, François

    2016-03-01

    Surface plasmon polaritons are electromagnetic waves coupled to collective electron oscillations propagating along metal-dielectric interfaces, exhibiting a bosonic character. Recent experiments involving surface plasmons guided by wires or stripes allowed the reproduction of quantum optics effects, such as antibunching with a single surface plasmon state, coalescence with a two-plasmon state, conservation of squeezing, or entanglement through plasmonic channels. We report the first direct demonstration of the wave-particle duality for a single surface plasmon freely propagating along a planar metal-air interface. We develop a platform that enables two complementary experiments, one revealing the particle behavior of the single-plasmon state through antibunching, and the other one where the interferences prove its wave nature. This result opens up new ways to exploit quantum conversion effects between different bosonic species as shown here with photons and polaritons. PMID:26998521

  5. Single-plasmon interferences

    PubMed Central

    Dheur, Marie-Christine; Devaux, Eloïse; Ebbesen, Thomas W.; Baron, Alexandre; Rodier, Jean-Claude; Hugonin, Jean-Paul; Lalanne, Philippe; Greffet, Jean-Jacques; Messin, Gaétan; Marquier, François

    2016-01-01

    Surface plasmon polaritons are electromagnetic waves coupled to collective electron oscillations propagating along metal-dielectric interfaces, exhibiting a bosonic character. Recent experiments involving surface plasmons guided by wires or stripes allowed the reproduction of quantum optics effects, such as antibunching with a single surface plasmon state, coalescence with a two-plasmon state, conservation of squeezing, or entanglement through plasmonic channels. We report the first direct demonstration of the wave-particle duality for a single surface plasmon freely propagating along a planar metal-air interface. We develop a platform that enables two complementary experiments, one revealing the particle behavior of the single-plasmon state through antibunching, and the other one where the interferences prove its wave nature. This result opens up new ways to exploit quantum conversion effects between different bosonic species as shown here with photons and polaritons. PMID:26998521

  6. High efficiency and low electromagnetic interference boost DC-DC converter

    NASA Astrophysics Data System (ADS)

    Yajun, Li; Xinquan, Lai; Qiang, Ye; Bing, Yuan

    2014-04-01

    A synchronous boost DC-DC converter with an adaptive dead time control (DTC) circuit and anti-ringing circuit is presented. The DTC circuit is used to provide adjustable dead time and zero inductor current detection for power transistors and therefore, a high efficiency is achieved by minimizing power losses, such as the shoot-through current loss, the body diode conduction loss, the charge-sharing loss and the reverse inductor current loss. Simultaneously, a novel anti-ringing circuit controlled by the switching sequence of power transistors is developed to suppress the ringing when the converter enters the discontinuous conduction mode (DCM) for low electromagnetic interference (EMI) and additional power savings. The proposed converter has been fabricated in a 0.6 μm CDMOS technology. Simulation and experimental results show that the power efficiency of the boost converter is above 81% under different load currents from 10 to 250 mA and a peak efficiency of 90% is achieved at about 100 mA. Moreover, the ringing is easily suppressed by the anti-ringing circuit and therefore the EMI noise is attenuated.

  7. Adaptive Control For Flexible Structures

    NASA Technical Reports Server (NTRS)

    Bayard, David S.; Ih, Che-Hang Charles; Wang, Shyh Jong

    1988-01-01

    Paper discusses ways to cope with measurement noise in adaptive control system for large, flexible structure in outer space. System generates control signals for torque and thrust actuators to turn all or parts of structure to desired orientations while suppressing torsional and other vibrations. Main result of paper is general theory for introduction of filters to suppress measurement noise while preserving stability.

  8. Interference Among Group A Arboviruses

    PubMed Central

    Zebovitz, Eugene; Brown, Arthur

    1968-01-01

    Interference among group A arboviruses is described which does not involve the mediation of interferon. Interference was observed only if the interfering virus had an advantage over the challenge virus, either in time or in multiplicity of infection. Adsorption, penetration, and uncoating of challenge virus did not appear to be inhibited, but the synthesis of infectious viral ribonucleic acid of the challenge virus was significantly retarded. It was shown with temperature-sensitive viruses or mutants that the replication of viral ribonucleic acid by the interfering virus was required to establish interference. A mechanism of interference based on a competition for replication sites or substrates is compared with other possible explanations. PMID:5701825

  9. Quantum Interference in Graphene Nanoconstrictions.

    PubMed

    Gehring, Pascal; Sadeghi, Hatef; Sangtarash, Sara; Lau, Chit Siong; Liu, Junjie; Ardavan, Arzhang; Warner, Jamie H; Lambert, Colin J; Briggs, G Andrew D; Mol, Jan A

    2016-07-13

    We report quantum interference effects in the electrical conductance of chemical vapor deposited graphene nanoconstrictions fabricated using feedback controlled electroburning. The observed multimode Fabry-Pérot interferences can be attributed to reflections at potential steps inside the channel. Sharp antiresonance features with a Fano line shape are observed. Theoretical modeling reveals that these Fano resonances are due to localized states inside the constriction, which couple to the delocalized states that also give rise to the Fabry-Pérot interference patterns. This study provides new insight into the interplay between two fundamental forms of quantum interference in graphene nanoconstrictions. PMID:27295198

  10. [shRNAs driven by K14 promoter induce tissue-specific RNA interference].

    PubMed

    Dai, Rong; Shen, Si-Jun; Wan, Peng-Cheng; Shi, Guo-Qing; Meng, Qing-Yong; Liu, Shou-Ren

    2011-07-01

    RNA interference is an efficient method for exploring gene function. Accumulating evidence suggests that RNA Pol II promoters can direct cell- or tissue-specific gene silencing. A eGFP-shRNA fusion construct transcribed from an RNA Pol II promoter (K14 promoter) was used to induce gene-specific shRNA silencing ofBMP4 gene expression. Recombinant vectors (pEGFP-C1-shRNA, psiCHECK-BMP4, and pEGFP-K14-shRNA) were constructed. Vectors pEGFP-C1-shRNA and psiCHECK-BMP4 were cotransfected into Hela cells (in vitro) and shRNA-induced inhibition efficiency was tested by a luciferase assay. The results showed that all the six interference sequences inhibited the expression of BMP4 with high efficiency (>60%), and the interference sequence 5# showed the highest efficiency. For in vivo screening of JB6-C41 cells transfected with vector pEGFP-K14-shRNA, the inhibition efficiency was assayed by quantitative RT-PCR and Western blotting analyses. The results showed that the mRNA and protein products of the exogenous BMP4 gene were efficiently and specifically inhibited. The efficiency of gene silencing was greater than 60%, except for sequence 3#. The declines in mRNA and protein expression levels were significantly correlated during gene silence by the shRNA. This system may be adapted for in vivo shRNA expression and gene silencing. This method may provide a novel approach for the application of RNAi technology in suppressing gene expression in the analysis of the mechanisms of hair follicle development in sheep. PMID:22049690

  11. The role of suppression in figurative language comprehension✩

    PubMed Central

    Gemsbacher, Morton Ann; Robertson, Rachel R.W.

    2014-01-01

    In this paper, we describe the crucial role that suppression plays in many aspects of language comprehension. We define suppression as a general, cognitive mechanism, the purpose of which is to attenuate the interference caused by the activation of extraneous, unnecessary, or inappropriate information. We illustrate the crucial role that suppression plays in general comprehension by reviewing numerous experiments. These experiments demonstrate that suppression attenuates interference during lexical access (how word meanings are ‘accessed’), anaphoric reference (how referents for anaphors, like pronouns, are computed), cataphoric reference (how concepts that are marked by devices, such as spoken stress, gain a privileged status), syntactic parsing (how grammatical forms of sentences are decoded), and individual differences in (adult) language comprehension skill. We also review research that suggests that suppression plays a crucial role in the understanding of figurative language, in particular, metaphors, idioms, and proverbs. PMID:25520540

  12. FPGA-based RF interference reduction techniques for simultaneous PET–MRI

    NASA Astrophysics Data System (ADS)

    Gebhardt, P.; Wehner, J.; Weissler, B.; Botnar, R.; Marsden, P. K.; Schulz, V.

    2016-05-01

    The combination of positron emission tomography (PET) and magnetic resonance imaging (MRI) as a multi-modal imaging technique is considered very promising and powerful with regard to in vivo disease progression examination, therapy response monitoring and drug development. However, PET–MRI system design enabling simultaneous operation with unaffected intrinsic performance of both modalities is challenging. As one of the major issues, both the PET detectors and the MRI radio-frequency (RF) subsystem are exposed to electromagnetic (EM) interference, which may lead to PET and MRI signal-to-noise ratio (SNR) deteriorations. Early digitization of electronic PET signals within the MRI bore helps to preserve PET SNR, but occurs at the expense of increased amount of PET electronics inside the MRI and associated RF field emissions. This raises the likelihood of PET-related MRI interference by coupling into the MRI RF coil unwanted spurious signals considered as RF noise, as it degrades MRI SNR and results in MR image artefacts. RF shielding of PET detectors is a commonly used technique to reduce PET-related RF interferences, but can introduce eddy-current-related MRI disturbances and hinder the highest system integration. In this paper, we present RF interference reduction methods which rely on EM field coupling–decoupling principles of RF receive coils rather than suppressing emitted fields. By modifying clock frequencies and changing clock phase relations of digital circuits, the resulting RF field emission is optimised with regard to a lower field coupling into the MRI RF coil, thereby increasing the RF silence of PET detectors. Our methods are demonstrated by performing FPGA-based clock frequency and phase shifting of digital silicon photo-multipliers (dSiPMs) used in the PET modules of our MR-compatible Hyperion II D PET insert. We present simulations and magnetic-field map scans visualising the impact of altered clock phase pattern on the spatial RF field

  13. FPGA-based RF interference reduction techniques for simultaneous PET-MRI.

    PubMed

    Gebhardt, P; Wehner, J; Weissler, B; Botnar, R; Marsden, P K; Schulz, V

    2016-05-01

    The combination of positron emission tomography (PET) and magnetic resonance imaging (MRI) as a multi-modal imaging technique is considered very promising and powerful with regard to in vivo disease progression examination, therapy response monitoring and drug development. However, PET-MRI system design enabling simultaneous operation with unaffected intrinsic performance of both modalities is challenging. As one of the major issues, both the PET detectors and the MRI radio-frequency (RF) subsystem are exposed to electromagnetic (EM) interference, which may lead to PET and MRI signal-to-noise ratio (SNR) deteriorations. Early digitization of electronic PET signals within the MRI bore helps to preserve PET SNR, but occurs at the expense of increased amount of PET electronics inside the MRI and associated RF field emissions. This raises the likelihood of PET-related MRI interference by coupling into the MRI RF coil unwanted spurious signals considered as RF noise, as it degrades MRI SNR and results in MR image artefacts. RF shielding of PET detectors is a commonly used technique to reduce PET-related RF interferences, but can introduce eddy-current-related MRI disturbances and hinder the highest system integration. In this paper, we present RF interference reduction methods which rely on EM field coupling-decoupling principles of RF receive coils rather than suppressing emitted fields. By modifying clock frequencies and changing clock phase relations of digital circuits, the resulting RF field emission is optimised with regard to a lower field coupling into the MRI RF coil, thereby increasing the RF silence of PET detectors. Our methods are demonstrated by performing FPGA-based clock frequency and phase shifting of digital silicon photo-multipliers (dSiPMs) used in the PET modules of our MR-compatible Hyperion II (D) PET insert. We present simulations and magnetic-field map scans visualising the impact of altered clock phase pattern on the spatial RF field

  14. The RNA interference revolution.

    PubMed

    Lenz, G

    2005-12-01

    The discovery of double-stranded RNA-mediated gene silencing has rapidly led to its use as a method of choice for blocking a gene, and has turned it into one of the most discussed topics in cell biology. Although still in its infancy, the field of RNA interference has already produced a vast array of results, mainly in Caenorhabditis elegans, but recently also in mammalian systems. Micro-RNAs are short hairpins of RNA capable of blocking translation, which are transcribed from genomic DNA and are implicated in several aspects from development to cell signaling. The present review discusses the main methods used for gene silencing in cell culture and animal models, including the selection of target sequences, delivery methods and strategies for a successful silencing. Expected developments are briefly discussed, ranging from reverse genetics to therapeutics. Thus, the development of the new paradigm of RNA-mediated gene silencing has produced two important advances: knowledge of a basic cellular mechanism present in the majority of eukaryotic cells and access to a potent and specific new method for gene silencing. PMID:16302089

  15. Serum indices: managing assay interference.

    PubMed

    Farrell, Christopher-John L; Carter, Andrew C

    2016-09-01

    Clinical laboratories frequently encounter samples showing significant haemolysis, icterus or lipaemia. Technical advances, utilizing spectrophotometric measurements on automated chemistry analysers, allow rapid and accurate identification of such samples. However, accurate quantification of haemolysis, icterus and lipaemia interference is of limited value if laboratories do not set rational alert limits, based on sound interference testing experiments. Furthermore, in the context of increasing consolidation of laboratories and the formation of laboratory networks, there is an increasing requirement for harmonization of the handling of haemolysis, icterus and lipaemia-affected samples across different analytical platforms. Harmonization may be best achieved by considering both the analytical aspects of index measurement and the possible variations in the effects of haemolysis, icterus and lipaemia interferences on assays from different manufacturers. Initial verification studies, followed up with ongoing quality control testing, can help a laboratory ensure the accuracy of haemolysis, icterus and lipaemia index results, as well as assist in managing any biases in index results from analysers from different manufacturers. Similarities, and variations, in the effect of haemolysis, icterus and lipaemia interference in assays from different manufacturers can often be predicted from the mechanism of interference. Nevertheless, interference testing is required to confirm expected similarities or to quantify differences. It is important that laboratories are familiar with a number of interference testing protocols and the particular strengths and weaknesses of each. A rigorous approach to all aspects of haemolysis, icterus and lipaemia interference testing allows the analytical progress in index measurement to be translated into improved patient care. PMID:27147624

  16. Interference Phenomenon with Mobile Displays

    ERIC Educational Resources Information Center

    Trantham, Kenneth

    2015-01-01

    A simple experiment is presented in which the spacing and geometric pattern of pixels in mobile displays is measured. The technique is based on optical constructive interference. While the experiment is another opportunity to demonstrate wave interference from a grating-like structure, this can also be used to demonstrate concepts of solid state…

  17. Supersonic Wave Interference Affecting Stability

    NASA Technical Reports Server (NTRS)

    Love, Eugene S.

    1958-01-01

    Some of the significant interference fields that may affect stability of aircraft at supersonic speeds are briefly summarized. Illustrations and calculations are presented to indicate the importance of interference fields created by wings, bodies, wing-body combinations, jets, and nacelles.

  18. Output Interference in Recognition Memory

    ERIC Educational Resources Information Center

    Criss, Amy H.; Malmberg, Kenneth J.; Shiffrin, Richard M.

    2011-01-01

    Dennis and Humphreys (2001) proposed that interference in recognition memory arises solely from the prior contexts of the test word: Interference does not arise from memory traces of other words (from events prior to the study list or on the study list, and regardless of similarity to the test item). We evaluate this model using output…

  19. Transient electromagnetic interference in substations

    SciTech Connect

    Wiggins, C.M.; Thomas, D.E.; Nickel, F.S.; Salas, T.M. ); Wright, S.E. )

    1994-10-01

    Electromagnetic interference levels on sensitive electronic equipment are quantified experimentally and theoretically in air and gas insulated substations of different voltages. Measurement techniques for recording interference voltages and currents and electric and magnetic fields are reviewed and actual interference data are summarized. Conducted and radiated interference coupling mechanisms and levels in substation control wiring are described using both measurement results and electromagnetic models validated against measurements. The nominal maximum field and control wire interference levels expected in the switchyard and inside the control house from switching operations, faults, and an average lightning strike are estimated using high frequency transient coupling models. Comparisons with standards are made and recommendations given concerning equipment shielding and surge protection.

  20. Sagnac interference in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Bishara, Waheb; Refael, Gil; Bockrath, Marc

    2008-10-01

    The Sagnac interference mode arises when two interfering counterpropogating beams traverse a loop, but with their velocities detuned by a small amount 2u , with vR/L=vF±u . In this paper we perform a perturbative nonequilibrium calculation of Sagnac interference in single-channel wires as well as armchair nanotube loops. We study the dependence of the Sagnac conductance oscillations on temperature and interactions. We find that the Sagnac interference is not destroyed by strong interactions, but becomes weakly dependent on the velocity detuning u . In armchairs nanotubes with typical interaction strength, 0.25≤g≤0.5 , we find that the necessary temperature for observing the interference effect, TSAG is also only weakly dependent on the interaction, and is enhanced by a factor of 8 relative to the temperature necessary for observing Fabry-Pérot interference in the same system, TFP .

  1. Reproductive interference between animal species.

    PubMed

    Gröning, Julia; Hochkirch, Axel

    2008-09-01

    Although sexual interactions between species (reproductive interference) have been reported from a wide range of animal taxa, their potential for determining species coexistence is often disregarded. Here, we review evidence from laboratory and field studies illustrating that heterospecific sexual interactions are frequently associated with fitness loss and can have severe ecological and evolutionary consequences. We define reproductive interference as any kind of interspecific interaction during the process of mate acquisition that adversely affects the fitness of at least one of the species involved and that is caused by incomplete species recognition. We distinguish seven types of reproductive interference: signal jamming, heterospecific rivalry, misdirected courtship, heterospecific mating attempts, erroneous female choice, heterospecific mating, and hybridization. We then discuss the sex-specific costs of these types and highlight two typical features of reproductive interference: density-dependence and asymmetry. Similar to competition, reproductive interference can lead to displacement of one species (sexual exclusion), spatial, temporal, or habitat segregation, changes in life history parameters, and reproductive character displacement. In many cases, patterns of coexistence might be shaped by reproductive interference rather than by resource competition, as the presence of a few heterospecifics might substantially decrease reproductive success. Therefore, interspecific sexual interactions should receive more attention in ecological research. Reproductive interference has mainly been discussed in the context of invasive species or hybrid zones, whereas its influence on naturally-occurring sympatric species pairs has rarely been addressed. To improve our knowledge of the ecological significance of reproductive interference, findings from laboratory experiments should be validated in the field. Future studies should also focus on ecological mechanisms, such

  2. Isolation and Adaptation in Passage Memory.

    ERIC Educational Resources Information Center

    Hertel, Paula T.

    1985-01-01

    Examines the phenomena of isolation and adaptation in the context of two recognition experiments investigating retroactive interference. Results suggest a framework for predicting errors and accuracies in passage memory based on integrative processing. (DF)

  3. Adaptation to (non)valent task disturbance.

    PubMed

    Kunde, Wilfried; Augst, Susanne; Kleinsorge, Thomas

    2012-12-01

    The cognitive system adapts to disturbances caused by task-irrelevant information. For example, interference due to irrelevant spatial stimulation (e.g., the spatial Simon effect) typically diminishes right after a spatially incongruent event. These adaptation effects reflect processes that help to overcome the impact of task-irrelevant information. Interference with (or interruption of) task processing can also result from valent (i.e., positive or negative) stimuli, such as in the "affective Simon" task. In the present study, we tested whether the resolution of valence-based task disturbances generalizes to the resolution of other cognitive (spatial) types of interference, and vice versa. Experiments 1 and 2 explored the interplay of adaptation effects triggered by spatial and affective interference. Incongruent spatial information modified the spatial Simon effect but not affective interference effects, whereas incongruent affective information modified affective interference effects to some extent, but not spatial Simon effects. In Experiment 3, we investigated the interplay of adaptation effects triggered by spatial interference and by the interruption of task processing from valent information that did not overlap with the main task ("emotional Stroop" effect). Again we observed domain-specific adaptation for the spatial Simon effect but found no evidence for cross-domain modulations. We assume that the processes used to resolve task disturbance from irrelevant affective and spatial information operate in largely independent manners. PMID:22936069

  4. RNA Interference in Infectious Tropical Diseases

    PubMed Central

    Hong, Young S.

    2008-01-01

    Introduction of double-stranded RNA (dsRNA) into some cells or organisms results in degradation of its homologous mRNA, a process called RNA interference (RNAi). The dsRNAs are processed into short interfering RNAs (siRNAs) that subsequently bind to the RNA-induced silencing complex (RISC), causing degradation of target mRNAs. Because of this sequence-specific ability to silence target genes, RNAi has been extensively used to study gene functions and has the potential to control disease pathogens or vectors. With this promise of RNAi to control pathogens and vectors, this paper reviews the current status of RNAi in protozoans, animal parasitic helminths and disease-transmitting vectors, such as insects. Many pathogens and vectors cause severe parasitic diseases in tropical regions and it is difficult to control once the host has been invaded. Intracellularly, RNAi can be highly effective in impeding parasitic development and proliferation within the host. To fully realize its potential as a means to control tropical diseases, appropriate delivery methods for RNAi should be developed, and possible off-target effects should be minimized for specific gene suppression. RNAi can also be utilized to reduce vector competence to interfere with disease transmission, as genes critical for pathogenesis of tropical diseases are knockdowned via RNAi. PMID:18344671

  5. Optical interference with digital holograms

    NASA Astrophysics Data System (ADS)

    Gossman, David; Perez-Garcia, Benjamin; Hernandez-Aranda, Raul I.; Forbes, Andrew

    2016-07-01

    In 1804, Thomas Young reported the observation of fringes in the intensity of light, and attributed it to the concept of interference between coherent sources. In this paper, we revisit this famous experiment and show how it can easily be demonstrated with digital holography. We look closely at the concept of interference with light and ask, "fringes in what?" We then show that depending on how light interferes, fringe patterns in observables other than intensity can be seen. We explain this conceptually and demonstrate it experimentally. We provide a holistic approach to the topic, aided by modern laboratory practices for a straightforward demonstration of the underlying physics.

  6. Age Differences in Implicit Interference

    PubMed Central

    Ikier, Simay; Hasher, Lynn

    2006-01-01

    We assessed age differences in interference effects in priming by using fragment completion. In Experiment 1, noninterfering filler words preceded critical targets at study, and priming was age invariant. In Experiment 2, the same target items had interfering competitors at the beginning of the list, such that both the target and the competitor were legitimate solutions to a fragment. Having two responses to a cue was disruptive for older adults, but not for younger adults. Younger and older adults differ in their susceptibility to interference in implicit tasks, and interference may play a role in influencing the magnitude of age differences in priming. PMID:16960231

  7. The Skin Microbiome: Is It Affected by UV-induced Immune Suppression?

    PubMed Central

    Patra, VijayKumar; Byrne, Scott N.; Wolf, Peter

    2016-01-01

    Human skin apart from functioning as a physical barricade to stop the entry of pathogens, also hosts innumerable commensal organisms. The skin cells and the immune system constantly interact with microbes, to maintain cutaneous homeostasis, despite the challenges offered by various environmental factors. A major environmental factor affecting the skin is ultraviolet radiation (UV-R) from sunlight. UV-R is well known to modulate the immune system, which can be both beneficial and deleterious. By targeting the cells and molecules within skin, UV-R can trigger the production and release of antimicrobial peptides, affect the innate immune system and ultimately suppress the adaptive cellular immune response. This can contribute to skin carcinogenesis and the promotion of infectious agents such as herpes simplex virus and possibly others. On the other hand, a UV-established immunosuppressive environment may protect against the induction of immunologically mediated skin diseases including some of photodermatoses such as polymorphic light eruption. In this article, we share our perspective about the possibility that UV-induced immune suppression may alter the landscape of the skin’s microbiome and its components. Alternatively, or in concert with this, direct UV-induced DNA and membrane damage to the microbiome may result in pathogen associated molecular patterns (PAMPs) that interfere with UV-induced immune suppression. PMID:27559331

  8. The Skin Microbiome: Is It Affected by UV-induced Immune Suppression?

    PubMed

    Patra, VijayKumar; Byrne, Scott N; Wolf, Peter

    2016-01-01

    Human skin apart from functioning as a physical barricade to stop the entry of pathogens, also hosts innumerable commensal organisms. The skin cells and the immune system constantly interact with microbes, to maintain cutaneous homeostasis, despite the challenges offered by various environmental factors. A major environmental factor affecting the skin is ultraviolet radiation (UV-R) from sunlight. UV-R is well known to modulate the immune system, which can be both beneficial and deleterious. By targeting the cells and molecules within skin, UV-R can trigger the production and release of antimicrobial peptides, affect the innate immune system and ultimately suppress the adaptive cellular immune response. This can contribute to skin carcinogenesis and the promotion of infectious agents such as herpes simplex virus and possibly others. On the other hand, a UV-established immunosuppressive environment may protect against the induction of immunologically mediated skin diseases including some of photodermatoses such as polymorphic light eruption. In this article, we share our perspective about the possibility that UV-induced immune suppression may alter the landscape of the skin's microbiome and its components. Alternatively, or in concert with this, direct UV-induced DNA and membrane damage to the microbiome may result in pathogen associated molecular patterns (PAMPs) that interfere with UV-induced immune suppression. PMID:27559331

  9. RNA Interference in Ticks

    PubMed Central

    Kocan, Katherine M.; Blouin, Edmour; de la Fuente, José

    2011-01-01

    Ticks are obligate hematophagous ectoparasites of wild and domestic animals and humans, and are considered to be second worldwide to mosquitoes as vectors of human diseases1 and the most important vectors affecting cattle industry worldwide2. Ticks are classified in the subclass Acari, order Parasitiformes, suborder Ixodida and are distributed worldwide from Arctic to tropical regions3. Despite efforts to control tick infestations, these ectoparasites remain a serious problem for human and animal health4,5. RNA interference (RNAi)6 is a nucleic acid-based reverse genetic approach that involves disruption of gene expression in order to determine gene function or its effect on a metabolic pathway. Small interfering RNAs (siRNAs) are the effector molecules of the RNAi pathway that is initiated by double-stranded RNA (dsRNA) and results in a potent sequence-specific degradation of cytoplasmic mRNAs containing the same sequence as the dsRNA trigger7-9. Post-transcriptional gene silencing mechanisms initiated by dsRNA have been discovered in all eukaryotes studied thus far, and RNAi has been rapidly developed in a variety of organisms as a tool for functional genomics studies and other applications10. RNAi has become the most widely used gene-silencing technique in ticks and other organisms where alternative approaches for genetic manipulation are not available or are unreliable5,11. The genetic characterization of ticks has been limited until the recent application of RNAi12,13. In the short time that RNAi has been available, it has proved to be a valuable tool for studying tick gene function, the characterization of the tick-pathogen interface and the screening and characterization of tick protective antigens14. Herein, a method for RNAi through injection of dsRNA into unfed ticks is described. It is likely that the knowledge gained from this experimental approach will contribute markedly to the understanding of basic biological systems and the development of vaccines

  10. Wind tunnel wall interference (January 1980 - May 1988): A selected, annotated bibliography

    NASA Technical Reports Server (NTRS)

    Tuttle, Marie H.; Cole, Karen L.

    1988-01-01

    This selected bibliography lists 423 entries on the subject of wall interference during testing in wind tunnels. It is the third in a series of bibliographies on the subject. The first, NASA TM-87639, August 1986, is concerned with the reduction of wall interference by the use of adaptive walls. The second, NASA TP-89066, December 1986, is on wall interference in V/STOL and high lift testing. This, the third in the series, covers the wall interference literature published during the period January 1980 through May 1988, generally excluding those topics covered in the first two parts.

  11. Interference colors with ''hidden'' polarizers

    NASA Astrophysics Data System (ADS)

    Silverman, Mark P.

    1981-09-01

    The author demonstrates the importance of polarizers when investigating interference colors in birefringence by considering a special case of cellophane placed on a smooth kitchen table illuminated from behind by an open window.(AIP)

  12. Interference Colors in Thin Films.

    ERIC Educational Resources Information Center

    Armstrong, H. L.

    1979-01-01

    Explains interference colors in thin films as being due to the removal, or considerable reduction, of a certain color by destructive inteference that results in the complementary color being seen. (GA)

  13. Electromagnetic Interference In New Aircraft

    NASA Technical Reports Server (NTRS)

    Larsen, William E.

    1991-01-01

    Report reviews plans to develop tests and standards to ensure that digital avionics systems in new civil aircraft immune to electromagnetic interference (EMI). Updated standards reflect more severe environment and vulnerabilities of modern avionics.

  14. Modeling Interference in Genetic Recombination

    PubMed Central

    McPeek, M. S.; Speed, T. P.

    1995-01-01

    In analyzing genetic linkage data it is common to assume that the locations of crossovers along a chromosome follow a Poisson process, whereas it has long been known that this assumption does not fit the data. In many organisms it appears that the presence of a crossover inhibits the formation of another nearby, a phenomenon known as ``interference.'' We discuss several point process models for recombination that incorporate position interference but assume no chromatid interference. Using stochastic simulation, we are able to fit the models to a multilocus Drosophila dataset by the method of maximum likelihood. We find that some biologically inspired point process models incorporating one or two additional parameters provide a dramatically better fit to the data than the usual ``no-interference'' Poisson model. PMID:7713406

  15. Neural correlates of stimulus and response interference in a 2-1 mapping stroop task.

    PubMed

    Chen, Antao; Bailey, Kira; Tiernan, Brandy N; West, Robert

    2011-05-01

    Two sources of interference (i.e., stimulus and response) are believed to contribute to the Stroop interference effect. Some neurophysiological evidence reveals that different neuro-cognitive processes are related to stimulus and response interference in the Stroop and related tasks. However, other evidence indicates that similar patterns of neural recruitment may be associated with these two types interference. Given these discrepant findings, the current study used a 2-1 mapping Stroop task in combination with event-related brain potentials (ERPs) to examine the neural correlates of stimulus and response interference. The response time data revealed that stimulus interference was constant across the response time distribution. In contrast, response interference increased in magnitude across the response time distribution for all but the slowest trials. The stimulus-locked ERP data revealed that early and later modulations of the medial frontal negativity may be sensitive to response interference, but not stimulus interference. These data also revealed that the conflict slow potential (SP) over the parietal and right lateral frontal regions was sensitive to both stimulus and response interference; in contrast, the conflict SP over the left lateral frontal region was only sensitive to response interference. Together the stimulus- and response-locked data lead to the conclusion that the parietal region is primarily involved in response selection in the Stroop task, and that the lateral frontal regions may participate in response monitoring and conflict adaption. PMID:21356252

  16. Optical Realization of Double-Continuum Fano Interference and Coherent Control in Plasmonic Metasurfaces

    NASA Astrophysics Data System (ADS)

    Arju, Nihal; Ma, Tzuhsuan; Khanikaev, Alexander; Purtseladze, David; Shvets, Gennady

    2015-06-01

    Classical realization of a ubiquitous quantum mechanical phenomenon of double-continuum Fano interference using metasurfaces is experimentally demonstrated by engineering the near-field interaction between two bright and one dark plasmonic modes. The competition between the bright modes, one of them effectively suppressing the Fano interference for the orthogonal light polarization, is discovered. Coherent control of optical energy concentration and light absorption by the ellipticity of the incident light is theoretically predicted.

  17. Optical Realization of Double-Continuum Fano Interference and Coherent Control in Plasmonic Metasurfaces.

    PubMed

    Arju, Nihal; Ma, Tzuhsuan; Khanikaev, Alexander; Purtseladze, David; Shvets, Gennady

    2015-06-12

    Classical realization of a ubiquitous quantum mechanical phenomenon of double-continuum Fano interference using metasurfaces is experimentally demonstrated by engineering the near-field interaction between two bright and one dark plasmonic modes. The competition between the bright modes, one of them effectively suppressing the Fano interference for the orthogonal light polarization, is discovered. Coherent control of optical energy concentration and light absorption by the ellipticity of the incident light is theoretically predicted. PMID:26196826

  18. Engineered decoherence: Characterization and suppression

    NASA Astrophysics Data System (ADS)

    Hegde, Swathi S.; Mahesh, T. S.

    2014-06-01

    Due to omnipresent environmental interferences, quantum coherences inevitably undergo irreversible transformations over certain time scales, thus leading to the loss of encoded information. This process, known as decoherence, has been a major obstacle in realizing efficient quantum information processors. Understanding the mechanism of decoherence is crucial in developing tools to inhibit it. Here we utilize a method proposed by Teklemariam et al. [Phys. Rev. A 67, 062316 (2003), 10.1103/PhysRevA.67.062316] to engineer artificial decoherence in the system qubits by randomly perturbing their surrounding ancilla qubits. Using a two-qubit nuclear magnetic resonance quantum register, we characterize the artificial decoherence by noise spectroscopy and quantum process tomography. Further, we study the efficacy of dynamical decoupling sequences in suppressing the artificial decoherence. Here we describe the experimental results and their comparisons with theoretical simulations.

  19. Adaptive high temperature superconducting filters for interference rejection

    SciTech Connect

    Raihn, K.F.; Fenzi, N.O.; Hey-Shipton, G.L.; Saito, E.R.; Loung, P.V.; Aidnik, D.L.

    1996-07-01

    An optically switched high temperature superconducting (HTS) band-reject filter bank is presented. Fast low loss switching of high quality (Q) factor HTS filter elements enables digital selection of arbitrary pass-bands and stop-bands. Patterned pieces of GaAs and silicon are used in the manufacture of the photosensitive switches. Fiber optic cabling is used to transfer the optical energy from an LED to the switch. The fiber optic cable minimizes the thermal loading of the filter package and de-couples the switch`s power source from the RF circuit. This paper will discuss the development of a computer-controlled HTS bank of optically switchable, narrow band, high Q bandstop filters which incorporates a cryocooler to maintain the 77 K operating temperature of the HTS microwave circuit.

  20. Growth hormone suppression test

    MedlinePlus

    The growth hormone suppression test determines whether growth hormone production is being suppressed by high blood sugar. ... away. The lab measures the glucose and growth hormone (GH) levels in each sample.

  1. Dexamethasone suppression test

    MedlinePlus

    Dexamethasone suppression test measures whether adrenocorticotrophic hormone ( ACTH ) secretion by the pituitary can be suppressed. ... During this test, you will receive dexamethasone. This is a strong ... your blood is drawn so that the cortisol level in your blood ...

  2. Dexamethasone suppression test

    MedlinePlus

    DST; ACTH suppression test; Cortisol suppression test ... During this test, you will receive dexamethasone. This is a strong man-made (synthetic) glucocorticoid medication. Afterward, your blood is drawn ...

  3. Growth hormone suppression test

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/003376.htm Growth hormone suppression test To use the sharing features on this page, please enable JavaScript. The growth hormone suppression test determines whether growth hormone production is ...

  4. [Decomposition of Interference Hyperspectral Images Using Improved Morphological Component Analysis].

    PubMed

    Wen, Jia; Zhao, Jun-suo; Wang, Cai-ling; Xia, Yu-li

    2016-01-01

    As the special imaging principle of the interference hyperspectral image data, there are lots of vertical interference stripes in every frames. The stripes' positions are fixed, and their pixel values are very high. Horizontal displacements also exist in the background between the frames. This special characteristics will destroy the regular structure of the original interference hyperspectral image data, which will also lead to the direct application of compressive sensing theory and traditional compression algorithms can't get the ideal effect. As the interference stripes signals and the background signals have different characteristics themselves, the orthogonal bases which can sparse represent them will also be different. According to this thought, in this paper the morphological component analysis (MCA) is adopted to separate the interference stripes signals and background signals. As the huge amount of interference hyperspectral image will lead to glow iterative convergence speed and low computational efficiency of the traditional MCA algorithm, an improved MCA algorithm is also proposed according to the characteristics of the interference hyperspectral image data, the conditions of iterative convergence is improved, the iteration will be terminated when the error of the separated image signals and the original image signals are almost unchanged. And according to the thought that the orthogonal basis can sparse represent the corresponding signals but cannot sparse represent other signals, an adaptive update mode of the threshold is also proposed in order to accelerate the computational speed of the traditional MCA algorithm, in the proposed algorithm, the projected coefficients of image signals at the different orthogonal bases are calculated and compared in order to get the minimum value and the maximum value of threshold, and the average value of them is chosen as an optimal threshold value for the adaptive update mode. The experimental results prove that

  5. Ipsilateral medial olivocochlear reflex adaptation of the primary-source DPOAE component measured with pulsed tones

    NASA Astrophysics Data System (ADS)

    Dalhoff, Ernst; Zelle, Dennis; Gummer, Anthony W.

    2015-12-01

    Measurement of contralateral suppression or ipsilateral adaptation of DPOAE due to the medial olivocochlear reflex (MOCR) in humans has so far been complicated by interference between the two major contributors to a DPOAE signal, namely, the nonlinear and the reflection-source components. For instance, while the MOCR has been shown to act inhibitory to the cochlear amplifier, a considerable share of the measured responses has been reported to be of the excitatory type (e.g. 22% for contralateral adaptation in [11]), and it has been shown that the magnitudes of ipsilateral adaptation as well as contralateral suppression depend on the precise frequency choice relative to the position of dips in the DPOAE fine structure [3, 8]. To separate MOCR effects on both source components, we developed a paradigm consisting of five short f2 pulses presented during a 0.35 s on-period of the f1 primary within blocks of 1.35 s length. The responses at f1 and f2 were cancelled using the primary-tone phase variation technique [13]. In 16 normal-hearing subjects, we measured MOCR-induced ipsilateral adaptation at three near-by frequencies in the DPOAE fine structure, corresponding roughly to characteristic interference states between the two major source components of a DPOAE, i.e. constructive, destructive and quadrature interference. Measurements were performed in the frequency range 1.7 ≤ f2 ≤ 2 kHz, f2/f1 = 1.2, and with moderate primary-tone levels (L2 = 45 dB SPL, L1 = 57 dB SPL). Analysis of the DPOAE time traces showed that the nonlinear component typically presents inhibitory adaptation between the 1st and the 5th pulses (median: 0.92 dB). Fitting a single exponential function to the pooled data yielded adaptation of 1.49 dB. From 26 statistically significant MOCR effects (P < 0.1) ranging between 0.29 and 2.81 dB, no excitatory response was detected. The separation of the DPOAE sources when analysing MOCR effects on ipsilateral DPOAE offers the potential of investigating

  6. Theory of psychological adaptive modes.

    PubMed

    Lehti, Juha

    2016-05-01

    When an individual is facing a stressor and normal stress-response mechanism cannot guarantee sufficient adaptation, special emotional states, adaptive modes, are activated (for example a depressive reaction). Adaptive modes are involuntary states of mind, they are of comprehensive nature, they interfere with normal functioning, and they cannot be repressed or controlled the same way as many emotions. Their transformational nature differentiates them from other emotional states. The object of the adaptive mode is to optimize the problem-solving abilities according to the situation that has provoked the mode. Cognitions and emotions during the adaptive mode are different than in a normal mental state. These altered cognitions and emotional reactions guide the individual to use the correct coping skills in order to deal with the stressor. Successful adaptation will cause the adaptive mode to fade off since the adaptive mode is no longer necessary, and the process as a whole will lead to raised well-being. However, if the adaptation process is inadequate, then the transformation period is prolonged, and the adaptive mode will turn into a dysfunctional state. Many psychiatric disorders are such maladaptive processes. The maladaptive processes can be turned into functional ones by using adaptive skills that are used in functional adaptive processes. PMID:27063089

  7. Response selection involves executive control: evidence from the selective interference paradigm.

    PubMed

    Szmalec, Arnaud; Vandierendonck, André; Kemps, Eva

    2005-04-01

    In the present study, we investigated whether response selection involves executive control, using the selective interference paradigm within Baddeley's (1986) working memory framework. The interference from response selection was estimated by comparing the patterns of dual-task interference of simple and choice RT tasks with those of a number of established working memory tasks. In Experiment 1, we compared impairment of forward and backward verbal serial recall from the RT tasks and articulatory suppression. Experiment 2 measured the adverse effects of the RT tasks and matrix tapping on forward and backward visuospatial serial recall. Finally, in Experiment 3, we examined the impairment from the RT tasks with two measures of executive control--namely, letter and category fluency. Altogether, the three experiments demonstrated that response selection interferes with executive control and that the interference is not produced at the level of working memory's slave systems, which supports the assumption of executive involvement in response selection. PMID:16156187

  8. Feature-based attention modulates surround suppression

    PubMed Central

    Flevaris, Anastasia V.; Murray, Scott O.

    2015-01-01

    Stimuli appearing in the surround of the classical receptive field (CRF) can reduce neuronal firing and perceived contrast of a preferred stimulus in the CRF, a phenomenon referred to as surround suppression. Suppression is greatest when the surrounding stimulus has the same orientation and spatial frequency (SF) as the central target. Although spatial attention has been shown to influence surround suppression, the effects of feature-based attention have yet to be characterized. Using behavioral contrast adaptation in humans, we examined center-surround interactions between SF and orientation, and asked whether attending to one feature dimension versus the other influenced suppression. A center-surround triplet comprised of a central target Gabor and two flanking Gabors were used for adaptation. The flankers could have the same SF and orientation as the target, or differ in one or both of the feature dimensions. Contrast thresholds were measured for the target before and after adapting to center-surround triplets, and postadaptation thresholds were taken as an indirect measure of surround suppression. Both feature dimensions contributed to surround suppression and did not summate. Moreover, when center and surround had the same feature value in one dimension (e.g., same orientation) but had different values in the other dimension (e.g., different SF), there was more suppression when attention was directed to the feature dimension that matched between center and surround than when attention was directed to the feature dimension that differed. These results demonstrate that feature-based attention can influence center-surround interactions by enhancing the effects of the attended dimension. PMID:25630380

  9. Analyzing the Generality of Conflict Adaptation Effects

    ERIC Educational Resources Information Center

    Funes, Maria Jesus; Lupianez, Juan; Humphreys, Glyn

    2010-01-01

    Conflict adaptation effects refer to the reduction of interference when the incongruent stimulus occurs immediately after an incongruent trial, compared with when it occurs after a congruent trial. The present study analyzes the key conditions that lead to adaptation effects that are specific to the type of conflict involved versus those that are…

  10. Whirling waves in Interference experiments

    NASA Astrophysics Data System (ADS)

    Sinha, Urbasi; Sawant, Rahul; Samuel, Joseph; Sinha, Aninda; Sinha, Supurna

    2014-03-01

    In a double slit interference experiment, the wave function at the screen with both slits open is not exactly the sum of the wave functions with the slits individually open one at a time. The three scenarios represent three different boundary conditions and as such, the superposition principle should not be applicable. However, most well- known text books in quantum mechanics implicitly and/or explicitly use this assumption, the wave function hypothesis, which is only approximately true. In our present study, we have used the Feynman path integral formalism to quantify contributions from non-classical paths in interference experiments which provide a measurable deviation from the wave function hypothesis. A direct experimental demonstration for the existence of these non-classical paths is hard. We find that contributions from such paths can be significant and we propose simple three-slit interference experiments to directly confirm their existence. I will also describe some ongoing experimental efforts towards testing our theoretical findings.

  11. Design of an L-band Microwave Radiometer with Active Mitigation of Interference

    NASA Technical Reports Server (NTRS)

    Ellingson, S. W.; Johnson, J. T.

    2003-01-01

    Radio frequency interference (RFI) impairs L-band radiometry outside the protected 20 MHz frequency band around 1413 MHz. However, bandwidths of 100 MHz or more are desired for certain remote sensing applications as well as certain astronomy applications. Because much of the RFI in this band is from radars with pulse lengths on the order of microseconds, traditional radiometers (i.e., those which directly measure total power or power spectral density integrated over time scales of milliseconds or greater) are poorly-suited to this task. Simply reducing integration time and discarding contaminated outputs may not be a practical answer due to the wide variety of modulations and pulse lengths observed in L-band RFI signals, the dynamic and complex nature of the associated propagation channels, and the logistical effort associated with post-measurement data editing. This motivates the design and development of radiometers capable of coherent sampling and adaptive, real-time mitigation of interference. Such a radiometer will be described in this presentation. This design is capable of coherently-sampling up to 100 MHz bandwidth at L-band. RFI mitigation is implemented in FPGA components so that real-time suppression is achieved. The system currently uses a cascade of basic time- and frequency- domain detection and blanking techniques; more advanced algorithms are un- der consideration. The modular FPGA-based architecture provides other benefits, such as the ability to implement extremely stable digital filters and the ability to reconfigure the system "on the fly". An overview of the basic design along with on-the-air results from an initial implementation will be provided in the presentation. Related L-band RFI surveys will be described to illustrate the relevance of this approach in a variety of operating conditions.

  12. Design of an L-band Microwave Radiometer with Active Mitigation of Interference

    NASA Technical Reports Server (NTRS)

    Hampson, G. A.; Ellingson, S. W.; Johnson, J. T.

    2003-01-01

    Radio frequency interference (RFI) impairs L-band radiometry outside the protected 20 MHz frequency band around 1413 MHz. However, bandwidths of 100 MHz or more are desired for certain remote sensing applications as well as certain astronomy applications. Because much of the RFI in this band is from radars with pulse lengths on the order of microseconds, traditional radiometers (i.e., those which directly measure total power or power spectral density integrated over time scales of milliseconds or greater) are poorly-suited to this task. Simply reducing integration time and discarding contaminated outputs may not be a practical answer due to the wide variety of modulations and pulse lengths observed in L-band RFI signals, the dynamic and complex nature of the associated propagation channels, and the logistical effort associated with post-measurement data editing. This motivates the design and development of radiometers capable of coherent sampling and adaptive, real-time mitigation of interference. Such a radiometer will be described in this presentation. This design is capable of coherently-sampling up to 100 MHz bandwidth at L-band. RFI mitigation is implemented in FPGA components so that real-time suppression is achieved. The system currently uses a cascade of basic time- and frequency-domain detection and blanking techniques; more advanced algorithms are under consideration. The modular FPGA-based architecture provides other benefits, such as the ability to implement extremely stable digital filters and the ability to reconfigure the system "on the fly". An overview of the basic design along with on-the-air results from an initial implementation will be provided in the presentation. Related L-band RFI surveys will be described to illustrate the relevance of this approach in a variety of operating conditions.

  13. Water Mist fire suppression experiment

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Water Mist commercial research program is scheduled to fly an investigation on STS-107 in 2002. This investigation will be flown as an Experimental Mounting Structure (EMS) insert into the updated Combustion Module (CM-2), a sophisticated combustion chamber plus diagnostic equipment. (The investigation hardware is shown here mounted in a non-flight frame similar to the EMS.) Water Mist is a commercial research program by the Center for Commercial Applications of Combustion in Space (CCACS), a NASA Commercial Space Center located at the Colorado School of Mines, in Golden, CO and Industry Partner Environmental Engineering Concepts. The program is focused on developing water mist as a replacement for bromine-based chemical fire suppression agents (halons). By conducting the experiments in microgravity, interference from convection currents is minimized and fundamental knowledge can be gained. This knowledge is incorporated into models, which can be used to simulate a variety of physical environments. The immediate objective of the project is to study the effect of a fine water mist on a laminar propagating flame generated in a propane-air mixture at various equivalence ratios. The effects of droplet size and concentration on the speed of the flame front is used as a measure of the effectiveness of fire suppression in this highly controlled experimental environment.

  14. Intralist interference in recognition memory.

    PubMed

    Kim, K; Glanzer, M

    1995-09-01

    Three experiments on recognition memory were carried out to define the nature of intralist interference effects. Experiment 1 replicated the findings of an earlier study (A. I. Schulman, 1971) on what appeared to be combined study (input) and test (output) order effects and added information on the presence of speed-accuracy trade-off effects. Experiment 2 demonstrated that only test order was effective and that study order effects did not occur. Experiment 3 demonstrated again that only test order was effective and also showed that the effect remained when response times were controlled. Attention/likelihood theory was fitted to the data of the final, clarified interference effect. PMID:8744957

  15. Interference of probabilities in dynamics

    SciTech Connect

    Zak, Michail

    2014-08-15

    A new class of dynamical systems with a preset type of interference of probabilities is introduced. It is obtained from the extension of the Madelung equation by replacing the quantum potential with a specially selected feedback from the Liouville equation. It has been proved that these systems are different from both Newtonian and quantum systems, but they can be useful for modeling spontaneous collective novelty phenomena when emerging outputs are qualitatively different from the weighted sum of individual inputs. Formation of language and fast decision-making process as potential applications of the probability interference is discussed.

  16. Diffractive interference optical analyzer (DiOPTER)

    NASA Astrophysics Data System (ADS)

    Sasikumar, Harish; Prasad, Vishnu; Pal, Parama; Varma, Manoj M.

    2016-03-01

    This report demonstrates a method for high-resolution refractometric measurements using, what we have termed as, a Diffractive Interference Optical Analyzer (DiOpter). The setup consists of a laser, polarizer, a transparent diffraction grating and Si-photodetectors. The sensor is based on the differential response of diffracted orders to bulk refractive index changes. In these setups, the differential read-out of the diffracted orders suppresses signal drifts and enables time-resolved determination of refractive index changes in the sample cell. A remarkable feature of this device is that under appropriate conditions, the measurement sensitivity of the sensor can be enhanced by more than two orders of magnitude due to interference between multiply reflected diffracted orders. A noise-equivalent limit of detection (LoD) of 6x10-7 RIU was achieved in glass. This work focuses on devices with integrated sample well, made on low-cost PDMS. As the detection methodology is experimentally straightforward, it can be used across a wide array of applications, ranging from detecting changes in surface adsorbates via binding reactions to estimating refractive index (and hence concentration) variations in bulk samples. An exciting prospect of this technique is the potential integration of this device to smartphones using a simple interface based on transmission mode configuration. In a transmission configuration, we were able to achieve an LoD of 4x10-4 RIU which is sufficient to explore several applications in food quality testing and related fields. We are envisioning the future of this platform as a personal handheld optical analyzer for applications ranging from environmental sensing to healthcare and quality testing of food products.

  17. Protease inhibitors interfere with the necessary factors of carcinogenesis.

    PubMed Central

    Troll, W

    1989-01-01

    Many tumor promoters are inflammatory agents that stimulate the formation of oxygen radicals (.O2-) and hydrogen peroxide (H2O2) in phagocytic neutrophils. The neutrophils use the oxygen radicals to kill bacteria, which are recognized by the cell membrane of phagocytic cells causing a signal to mount the oxygen response. The tumor promoter isolated from croton oil, 12-O-tetradecanoylphorbol-13-acetate (TPA), mimics the signal, causing an oxygen radical release that is intended to kill bacteria; instead, it injures cells in the host. Oxygen radicals cause single strand breaks in DNA and modify DNA bases. These damaging reactions appear to be related to tumor promotion, as three types of chemopreventive agents, retinoids, onion oil, and protease inhibitors, suppress the induction of oxygen radicals in phagocytic neutrophils and suppress tumor promotion in skin cancer in mice. Protease inhibitors also suppress breast and colon cancers in mice. Protease inhibitors capable of inhibiting chymotrypsin show a greater suppression of the oxygen effect and are better suppressors of tumor promotion. In addition, oxygen radicals may be one of the many agents that cause activation of oncogenes. Since retinoids and protease inhibitors suppress the expression of the ras oncogene in NIH 3T3 cells, NIH 3T3 cells may serve as a relatively facile model for finding and measuring chemopreventive agents that interfere with the carcinogenic process. PMID:2667986

  18. Empirical mode decomposition based background removal and de-noising in polarization interference imaging spectrometer.

    PubMed

    Zhang, Chunmin; Ren, Wenyi; Mu, Tingkui; Fu, Lili; Jia, Chenling

    2013-02-11

    Based on empirical mode decomposition (EMD), the background removal and de-noising procedures of the data taken by polarization interference imaging interferometer (PIIS) are implemented. Through numerical simulation, it is discovered that the data processing methods are effective. The assumption that the noise mostly exists in the first intrinsic mode function is verified, and the parameters in the EMD thresholding de-noising methods is determined. In comparison, the wavelet and windowed Fourier transform based thresholding de-noising methods are introduced. The de-noised results are evaluated by the SNR, spectral resolution and peak value of the de-noised spectrums. All the methods are used to suppress the effect from the Gaussian and Poisson noise. The de-noising efficiency is higher for the spectrum contaminated by Gaussian noise. The interferogram obtained by the PIIS is processed by the proposed methods. Both the interferogram without background and noise free spectrum are obtained effectively. The adaptive and robust EMD based methods are effective to the background removal and de-noising in PIIS. PMID:23481716

  19. Effective knockdown of Drosophila long non-coding RNAs by CRISPR interference.

    PubMed

    Ghosh, Sanjay; Tibbit, Charlotte; Liu, Ji-Long

    2016-05-19

    Long non-coding RNAs (lncRNAs) have emerged as regulators of gene expression across metazoa. Interestingly, some lncRNAs function independently of their transcripts - the transcription of the lncRNA locus itself affects target genes. However, current methods of loss-of-function analysis are insufficient to address the role of lncRNA transcription from the transcript which has impeded analysis of their function. Using the minimal CRISPR interference (CRISPRi) system, we show that coexpression of the catalytically inactive Cas9 (dCas9) and guide RNAs targeting the endogenous roX locus in the Drosophila cells results in a robust and specific knockdown of roX1 and roX2 RNAs, thus eliminating the need for recruiting chromatin modifying proteins for effective gene silencing. Additionally, we find that the human and Drosophila codon optimized dCas9 genes are functional and show similar transcription repressive activity. Finally, we demonstrate that the minimal CRISPRi system suppresses roX transcription efficiently in vivo resulting in loss-of-function phenotype, thus validating the method for the first time in a multicelluar organism. Our analysis expands the genetic toolkit available for interrogating lncRNA function in situ and is adaptable for targeting multiple genes across model organisms. PMID:26850642

  20. Effective knockdown of Drosophila long non-coding RNAs by CRISPR interference

    PubMed Central

    Ghosh, Sanjay; Tibbit, Charlotte; Liu, Ji-Long

    2016-01-01

    Long non-coding RNAs (lncRNAs) have emerged as regulators of gene expression across metazoa. Interestingly, some lncRNAs function independently of their transcripts – the transcription of the lncRNA locus itself affects target genes. However, current methods of loss-of-function analysis are insufficient to address the role of lncRNA transcription from the transcript which has impeded analysis of their function. Using the minimal CRISPR interference (CRISPRi) system, we show that coexpression of the catalytically inactive Cas9 (dCas9) and guide RNAs targeting the endogenous roX locus in the Drosophila cells results in a robust and specific knockdown of roX1 and roX2 RNAs, thus eliminating the need for recruiting chromatin modifying proteins for effective gene silencing. Additionally, we find that the human and Drosophila codon optimized dCas9 genes are functional and show similar transcription repressive activity. Finally, we demonstrate that the minimal CRISPRi system suppresses roX transcription efficiently in vivo resulting in loss-of-function phenotype, thus validating the method for the first time in a multicelluar organism. Our analysis expands the genetic toolkit available for interrogating lncRNA function in situ and is adaptable for targeting multiple genes across model organisms. PMID:26850642

  1. Metameric interference security image structures.

    PubMed

    Baloukas, Bill; Martinu, Ludvik

    2008-04-01

    We study innovative interference security image structures based on metamerism. We have designed, fabricated, and evaluated different structures that can be used in transmission or in reflection. These metameric structures are either a combination of two different interference filters or of an interference filter and a noniridescent colored material. In the latter case, by closely matching the spectra, the sensitivity of the device to changes in light sources and observers is minimized. Because of the intrinsic color shift of interference filters, one can create a hidden image that appears at a specific observation angle. The presence of the hidden image, as well as in some cases of the noniridescent material, which serves as a color reference, increases the complexity of such devices while facilitating the user's authentication process as well as automatized detection by using a laser at a specific angle. We present the design approach, analyze the filters' sensitivity to deposition errors, and evaluate the performance of prototype devices prepared by dual ion beam sputtering. PMID:18382590

  2. Fano Interference in Classical Oscillators

    ERIC Educational Resources Information Center

    Satpathy, S.; Roy, A.; Mohapatra, A.

    2012-01-01

    We seek to illustrate Fano interference in a classical coupled oscillator by using classical analogues of the atom-laser interaction. We present an analogy between the dressed state picture of coherent atom-laser interaction and a classical coupled oscillator. The Autler-Townes splitting due to the atom-laser interaction is analogous to the…

  3. "Quantum Interference with Slits" Revisited

    ERIC Educational Resources Information Center

    Rothman, Tony; Boughn, Stephen

    2011-01-01

    Marcella has presented a straightforward technique employing the Dirac formalism to calculate single- and double-slit interference patterns. He claims that no reference is made to classical optics or scattering theory and that his method therefore provides a purely quantum mechanical description of these experiments. He also presents his…

  4. Suprasegmental Aspects of Reading Interference.

    ERIC Educational Resources Information Center

    Westbrook, Colston R.

    Information is presented in this paper regarding suprasegmental features of Black English thay may cause reading interference for some Black children. Much of the research concerning reading problems of many Afro-American students stresses the segmental differences of the phonology, the morphology, the syntax, and lexical selection between two…

  5. Frequency-doubling optoelectronic oscillator based on destructive interference

    NASA Astrophysics Data System (ADS)

    Jiang, Jun; Chen, Fushen; Fan, Mengqiu; Li, Chengxin; Dong, Qimeng

    2015-12-01

    A frequency-doubling optoelectronic oscillator (OEO) using two cascaded modulators based on destructive interference is proposed and experimentally demonstrated. In the proposed system, we utilize a cascaded modulator including a phase modulator and an intensity modulator, which implements a carrier-suppressed double-sideband modulation based on destructive interference to generate a frequency-doubled microwave signal. Meanwhile, the phase modulator is connected by a chirp fiber Bragg grating in the loop, which forms a microwave photonic filter to select the fundamental frequency signal in the OEO loop. As a result, a frequency-doubled microwave signal at 17.9 and 20.5 GHz is generated, respectively. The phase noises and the long-term stability of the generated microwave signals are also investigated.

  6. Constrained crosstalk resistant adaptive noise canceller

    NASA Astrophysics Data System (ADS)

    Parsa, V.; Parker, P.

    1994-08-01

    The performance of an adaptive noise canceller (ANC) is sensitive to the presence of signal `crosstalk' in the reference channel. The authors propose a novel approach to crosstalk resistant adaptive noise cancellation, namely the constrained crosstalk resistant adaptive noise canceller (CCRANC). The theoretical analysis of the CCRANC along with the constrained algorithm is presented. The performance of the CCRANC in recovering somatosensory evoked potentials (SEPs) from myoelectric interference is then evaluated through simulations.

  7. Adaptive Detector Arrays for Optical Communications Receivers

    NASA Technical Reports Server (NTRS)

    Vilnrotter, V.; Srinivasan, M.

    2000-01-01

    The structure of an optimal adaptive array receiver for ground-based optical communications is described and its performance investigated. Kolmogorov phase screen simulations are used to model the sample functions of the focal-plane signal distribution due to turbulence and to generate realistic spatial distributions of the received optical field. This novel array detector concept reduces interference from background radiation by effectively assigning higher confidence levels at each instant of time to those detector elements that contain significant signal energy and suppressing those that do not. A simpler suboptimum structure that replaces the continuous weighting function of the optimal receiver by a hard decision on the selection of the signal detector elements also is described and evaluated. Approximations and bounds to the error probability are derived and compared with the exact calculations and receiver simulation results. It is shown that, for photon-counting receivers observing Poisson-distributed signals, performance improvements of approximately 5 dB can be obtained over conventional single-detector photon-counting receivers, when operating in high background environments.

  8. Fire Suppression and Response

    NASA Technical Reports Server (NTRS)

    Ruff, Gary A.

    2004-01-01

    This report is concerned with the following topics regarding fire suppression:What is the relative effectiveness of candidate suppressants to extinguish a representative fire in reduced gravity, including high-O2 mole fraction, low -pressure environments? What are the relative advantages and disadvantages of physically acting and chemically-acting agents in spacecraft fire suppression? What are the O2 mole fraction and absolute pressure below which a fire cannot exist? What effect does gas-phase radiation play in the overall fire and post-fire environments? Are the candidate suppressants effective to extinguish fires on practical solid fuels? What is required to suppress non-flaming fires (smoldering and deep seated fires) in reduced gravity? How can idealized space experiment results be applied to a practical fire scenario? What is the optimal agent deployment strategy for space fire suppression?

  9. Measurement and suppression of secondary waves caused by high-order modes in a photonic bandgap fiber-optic gyroscope.

    PubMed

    Xu, Xiaobin; Gao, Fuyu; Song, Ningfang; Jin, Jing

    2016-05-16

    Air-core photonic bandgap fiber (PBF) is a good choice for fiber-optic gyroscopes (FOGs) owing to the fact that it can be adapted to a wide variety of environments. However, its multimode properties are disadvantageous for the application to FOGs. An interference-based method is proposed to precisely determine the secondary waves caused by the high-order modes and their coupling. Based on the method, two groups of secondary waves have been found, having optical path differences (OPDs) of ~1.859 m and ~0.85 m, respectively, relative to the primary waves in a PBFOG that consists of a 7-cell PBF coil, approximately 180 m in length. Multi-turn bends of the PBF at both ends of the PBF coil after the fusion splicing points are shown to suppress the intensity of these secondary waves by approximately 10 dB. PMID:27409849

  10. Constructive and destructive interferences of Stark resonances induced by an ac field in atomic hydrogen

    SciTech Connect

    Pawlak, Mariusz; Bylicki, Miroslaw; Moiseyev, Nimrod; Sindelka, Milan

    2010-12-15

    We study theoretically the problem of a hydrogen atom exposed both to a static dc field and to a monochromatic ac field. We show that, in the presence of an ac field, a constructive (or destructive) interference occurs between the excited (Rydberg) Stark resonance states and the hydrogenic ground state. This mechanism is responsible for dramatic enhancement (or suppression) of the corresponding photoionization rates.

  11. Applications of minimum redundancy arrays in adaptive beamforming

    NASA Astrophysics Data System (ADS)

    Fattouche, M.; Nichols, S. T.; Jorgenson, M. B.

    1991-10-01

    It is shown, through analysis and simulation, that the use of a minimum redundancy array (MRA) in conjunction with an adaptive beamformer results in performance superior to that attained by a comparable system based on an array with uniformly spaced elements, or uniform array (UA) in terms of rejecting interferences located in close angular proximity to the look direction. Further, it is demonstrated that choosing the adaptive elements of a thinned adaptive array (TAA) based on a minimum spatial redundancy criterion, rather than spacing them uniformly, results in improved rejection of main lobe interferences, with negligible degradation in sidelobe interference rejection capabilities.

  12. Neural Tuning Functions Underlie Both Generalization and Interference.

    PubMed

    Howard, Ian S; Franklin, David W

    2015-01-01

    In sports, the role of backswing is considered critical for generating a good shot, even though it plays no direct role in hitting the ball. We recently demonstrated the scientific basis of this phenomenon by showing that immediate past movement affects the learning and recall of motor memories. This effect occurred regardless of whether the past contextual movement was performed actively, passively, or shown visually. In force field studies, it has been shown that motor memories generalize locally and that the level of compensation decays as a function of movement angle away from the trained movement. Here we examine if the contextual effect of past movement exhibits similar patterns of generalization and whether it can explain behavior seen in interference studies. Using a single force-field learning task, the directional tuning curves of both the prior contextual movement and the subsequent force field adaptive movements were measured. The adaptation movement direction showed strong directional tuning, decaying to zero by 90° relative to the training direction. The contextual movement direction exhibited a similar directional tuning, although the effect was always above 60%. We then investigated the directional tuning of the passive contextual movement using interference tasks, where the contextual movements that uniquely specified the force field direction were separated by ±15° or ±45°. Both groups showed a pronounced tuning effect, which could be well explained by the directional tuning functions for single force fields. Our results show that contextual effect of past movement influences predictive force compensation, even when adaptation does not require contextual information. However, when such past movement contextual information is crucial to the task, such as in an interference study, it plays a strong role in motor memory learning and recall. This work demonstrates that similar tuning responses underlie both generalization of movement direction

  13. Neural Tuning Functions Underlie Both Generalization and Interference

    PubMed Central

    Howard, Ian S.; Franklin, David W.

    2015-01-01

    In sports, the role of backswing is considered critical for generating a good shot, even though it plays no direct role in hitting the ball. We recently demonstrated the scientific basis of this phenomenon by showing that immediate past movement affects the learning and recall of motor memories. This effect occurred regardless of whether the past contextual movement was performed actively, passively, or shown visually. In force field studies, it has been shown that motor memories generalize locally and that the level of compensation decays as a function of movement angle away from the trained movement. Here we examine if the contextual effect of past movement exhibits similar patterns of generalization and whether it can explain behavior seen in interference studies. Using a single force-field learning task, the directional tuning curves of both the prior contextual movement and the subsequent force field adaptive movements were measured. The adaptation movement direction showed strong directional tuning, decaying to zero by 90° relative to the training direction. The contextual movement direction exhibited a similar directional tuning, although the effect was always above 60%. We then investigated the directional tuning of the passive contextual movement using interference tasks, where the contextual movements that uniquely specified the force field direction were separated by ±15° or ±45°. Both groups showed a pronounced tuning effect, which could be well explained by the directional tuning functions for single force fields. Our results show that contextual effect of past movement influences predictive force compensation, even when adaptation does not require contextual information. However, when such past movement contextual information is crucial to the task, such as in an interference study, it plays a strong role in motor memory learning and recall. This work demonstrates that similar tuning responses underlie both generalization of movement direction

  14. Resolving semantic and proactive interference in memory over the short-term

    PubMed Central

    Reuter-Lorenz, Patricia A.; Lewis, Richard L.; Jonides, John

    2011-01-01

    Interference is a major source of short-term errors of memory. The present investigation explores the relationship between two important forms of interference: proactive interference (PI), induced by the need to reject recently studied items no longer relevant to task performance, and semantic interference (SI), induced by the need to reject lures sharing a meaningful relationship with current memoranda. We explore the possibility that shared cognitive control processes are recruited to resolve both forms of interference. In Experiment 1, we find that the requirement to engage in articulatory suppression during the retention interval of tasks that induce either PI or SI increases both forms of interference similarly and selectively. In Experiment 2, we develop a task to examine PI and SI within the same experimental context. The results show interactive effects between factors that lead to the two forms of interference. Taken together, these findings support contextual-cuing models of short-term remembering (Nairne, Annual Review of Psychology, 53, 53–81 2002), where the context in which retrieval occurs can influence susceptibility to interference. Lastly, we discuss several theoretical hypotheses concerning the cognitive control processes that are recruited to resolve SI and PI in short-term remembering. PMID:21327614

  15. EASI - EQUILIBRIUM AIR SHOCK INTERFERENCE

    NASA Technical Reports Server (NTRS)

    Glass, C. E.

    1994-01-01

    New research on hypersonic vehicles, such as the National Aero-Space Plane (NASP), has raised concerns about the effects of shock-wave interference on various structural components of the craft. State-of-the-art aerothermal analysis software is inadequate to predict local flow and heat flux in areas of extremely high heat transfer, such as the surface impingement of an Edney-type supersonic jet. EASI revives and updates older computational methods for calculating inviscid flow field and maximum heating from shock wave interference. The program expands these methods to solve problems involving the six shock-wave interference patterns on a two-dimensional cylindrical leading edge with an equilibrium chemically reacting gas mixture (representing, for example, the scramjet cowl of the NASP). The inclusion of gas chemistry allows for a more accurate prediction of the maximum pressure and heating loads by accounting for the effects of high temperature on the air mixture. Caloric imperfections and specie dissociation of high-temperature air cause shock-wave angles, flow deflection angles, and thermodynamic properties to differ from those calculated by a calorically perfect gas model. EASI contains pressure- and temperature-dependent thermodynamic and transport properties to determine heating rates, and uses either a calorically perfect air model or an 11-specie, 7-reaction reacting air model at equilibrium with temperatures up to 15,000 K for the inviscid flowfield calculations. EASI solves the flow field and the associated maximum surface pressure and heat flux for the six common types of shock wave interference. Depending on the type of interference, the program solves for shock-wave/boundary-layer interaction, expansion-fan/boundary-layer interaction, attaching shear layer or supersonic jet impingement. Heat flux predictions require a knowledge (from experimental data or relevant calculations) of a pertinent length scale of the interaction. Output files contain flow

  16. Nondominant-to-dominant hand interference in bimanual movements is facilitated by gradual visuomotor perturbation.

    PubMed

    Kagerer, F A

    2016-03-24

    In simultaneous bimanual movements, interference between the hands is always a possibility, particularly when movements are spatially incongruent. In a previous study using bimanual target-directed movements and abrupt visual feedback perturbation of one hand, I showed asymmetric interference from the dominant to the nondominant hand. The signature of that interference reflected the directional control strength of the dominant hand, supporting a recent theory of functional lateralization of arm movements, and extending it to a bimanual context. Nondominant-to-dominant interference was not observed in this task. The current study in healthy young adults used a bimanual paradigm in which one hand had to adapt to a gradual visuomotor perturbation, while the other hand operated under kinesthetic control, without visual feedback. In this arrangement, the kinesthetically guided hand provides a canvas on which the visually guided, and perturbed hand can 'paint' its interference. Results of this study showed two patterns of interference: in some participants the nonvisible hand deviated in the same direction (isodirectional) relative to the perturbed hand, in others it mirrored the direction (anisodirectional) of the perturbed hand. In isodirectional participants, dominant-to-nondominant and nondominant-to-dominant hand interference was symmetrical and relatively weak, whereas there was strong nondominant-to-dominant hand interference in anisodirectional participants, suggesting interference in the form of endpoint accuracy control strength of the nondominant hand. Based on these findings, the study discusses potential mechanisms enabling the nondominant hand to exert this control strength onto the dominant hand. PMID:26779835

  17. Suppression of the HSF1-mediated proteotoxic stress response by the metabolic stress sensor AMPK

    PubMed Central

    Dai, Siyuan; Tang, Zijian; Cao, Junyue; Zhou, Wei; Li, Huawen; Sampson, Stephen; Dai, Chengkai

    2015-01-01

    Numerous extrinsic and intrinsic insults trigger the HSF1-mediated proteotoxic stress response (PSR), an ancient transcriptional program that is essential to proteostasis and survival under such conditions. In contrast to its well-recognized mobilization by proteotoxic stress, little is known about how this powerful adaptive mechanism reacts to other stresses. Surprisingly, we discovered that metabolic stress suppresses the PSR. This suppression is largely mediated through the central metabolic sensor AMPK, which physically interacts with and phosphorylates HSF1 at Ser121. Through AMPK activation, metabolic stress represses HSF1, rendering cells vulnerable to proteotoxic stress. Conversely, proteotoxic stress inactivates AMPK and thereby interferes with the metabolic stress response. Importantly, metformin, a metabolic stressor and popular anti-diabetic drug, inactivates HSF1 and provokes proteotoxic stress within tumor cells, thereby impeding tumor growth. Thus, these findings uncover a novel interplay between the metabolic stress sensor AMPK and the proteotoxic stress sensor HSF1 that profoundly impacts stress resistance, proteostasis, and malignant growth. PMID:25425574

  18. REM sleep rescues learning from interference.

    PubMed

    McDevitt, Elizabeth A; Duggan, Katherine A; Mednick, Sara C

    2015-07-01

    Classical human memory studies investigating the acquisition of temporally-linked events have found that the memories for two events will interfere with each other and cause forgetting (i.e., interference; Wixted, 2004). Importantly, sleep helps consolidate memories and protect them from subsequent interference (Ellenbogen, Hulbert, Stickgold, Dinges, & Thompson-Schill, 2006). We asked whether sleep can also repair memories that have already been damaged by interference. Using a perceptual learning paradigm, we induced interference either before or after a consolidation period. We varied brain states during consolidation by comparing active wake, quiet wake, and naps with either non-rapid eye movement sleep (NREM), or both NREM and REM sleep. When interference occurred after consolidation, sleep and wake both produced learning. However, interference prior to consolidation impaired memory, with retroactive interference showing more disruption than proactive interference. Sleep rescued learning damaged by interference. Critically, only naps that contained REM sleep were able to rescue learning that was highly disrupted by retroactive interference. Furthermore, the magnitude of rescued learning was correlated with the amount of REM sleep. We demonstrate the first evidence of a process by which the brain can rescue and consolidate memories damaged by interference, and that this process requires REM sleep. We explain these results within a theoretical model that considers how interference during encoding interacts with consolidation processes to predict which memories are retained or lost. PMID:25498222

  19. Task duration in contextual interference.

    PubMed

    Smith, Peter J K

    2002-12-01

    Duration of practice trial on a pursuit rotor task in contextual interference was investigated. Participants practiced at each of 4 angular velocities, with 24 participants completing 28 trials lasting 20 sec., and 24 participants completing 112 trials of 5 sec. Half of the participants in each trial-duration condition practiced in a blocked format and half practiced in a random format. After random practice posttest performance was better than blocked practice when practice-trial duration was 20 sec., but worse when practice-trial duration was 5 sec. This result is not consistent with theoretical explanations of the contextual interference effect and is discussed with reference to the task characteristics and demands of the pursuit rotor. PMID:12578255

  20. Scaling behavior in interference lithography

    SciTech Connect

    Agayan, R.R.; Banyai, W.C.; Fernandez, A.

    1998-02-27

    Interference lithography is an emerging, technology that provides a means for achieving high resolution over large exposure areas (approximately 1 m{sup 2}) with virtually unlimited depth of field. One- and two-dimensional arrays of deep submicron structures can be created using near i-line wavelengths and standard resist processing. In this paper, we report on recent advances in the development of this technology, focusing, in particular, on how exposure latitude and resist profile scale with interference period We present structure width vs dose curves for periods ranging from 200 nm to 1 um, demonstrating that deep submicron structures can be generated with exposure latitudes exceeding 30%. Our experimental results are compared to simulations based on PROLITIV2.

  1. Silicon superconducting quantum interference device

    SciTech Connect

    Duvauchelle, J. E.; Francheteau, A.; Marcenat, C.; Lefloch, F.; Chiodi, F.; Débarre, D.; Hasselbach, K.; Kirtley, J. R.

    2015-08-17

    We have studied a Superconducting Quantum Interference Device (SQUID) made from a single layer thin film of superconducting silicon. The superconducting layer is obtained by heavily doping a silicon wafer with boron atoms using the gas immersion laser doping technique. The SQUID is composed of two nano-bridges (Dayem bridges) in a loop and shows magnetic flux modulation at low temperature and low magnetic field. The overall behavior shows very good agreement with numerical simulations based on the Ginzburg-Landau equations.

  2. Interference techniques in fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Dogan, Mehmet

    We developed a set of interference-based optical microscopy techniques to study biological structures through nanometer-scale axial localization of fluorescent biomarkers. Spectral self-interference fluorescence microscopy (SSFM) utilizes interference of direct and reflected waves emitted from fluorescent molecules in the vicinity of planar reflectors to reveal the axial position of the molecules. A comprehensive calculation algorithm based on Green's function formalism is presented to verify the validity of approximations used in a far-field approach that describes the emission of fluorescent markers near interfaces. Using the validated model, theoretical limits of axial localization were determined with emphasis given to numerical aperture (NA) dependence of localization uncertainty. SSFM was experimentally demonstrated in conformational analysis of nucleoproteins. In particular, interaction between surface-tethered 75-mer double strand DNA and integration host factor (IHF) protein was probed on Si-SiO2 substrates by determining the axial position of fluorescent labels attached to the free ends of DNA molecules. Despite its sub-nanometer precision axial localization capability, SSFM lacks high lateral resolution due to the low-NA requirement for planar reflectors. We developed a second technique, 4Pi-SSFM, which improves the lateral resolution of a conventional SSFM system by an order of magnitude while achieving nanometer-scale axial localization precision. Using two opposing high-NA objectives, fluorescence signal is interferometrically collected and spectral interference pattern is recorded. Axial position of emitters is found from analysis of the spectra. The 4Pi-SSFM technique was experimentally demonstrated by determining the surface profiles of fabricated glass surfaces and outer membranes of Shigella, a type of Gram-negative bacteria. A further discussion is presented to localize surface O antigen, which is an important oligosaccharide structure in the

  3. Quantum interference in plasmonic circuits.

    PubMed

    Heeres, Reinier W; Kouwenhoven, Leo P; Zwiller, Valery

    2013-10-01

    Surface plasmon polaritons (plasmons) are a combination of light and a collective oscillation of the free electron plasma at metal/dielectric interfaces. This interaction allows subwavelength confinement of light beyond the diffraction limit inherent to dielectric structures. As a result, the intensity of the electromagnetic field is enhanced, with the possibility to increase the strength of the optical interactions between waveguides, light sources and detectors. Plasmons maintain non-classical photon statistics and preserve entanglement upon transmission through thin, patterned metallic films or weakly confining waveguides. For quantum applications, it is essential that plasmons behave as indistinguishable quantum particles. Here we report on a quantum interference experiment in a nanoscale plasmonic circuit consisting of an on-chip plasmon beamsplitter with integrated superconducting single-photon detectors to allow efficient single plasmon detection. We demonstrate a quantum-mechanical interaction between pairs of indistinguishable surface plasmons by observing Hong-Ou-Mandel (HOM) interference, a hallmark non-classical interference effect that is the basis of linear optics-based quantum computation. Our work shows that it is feasible to shrink quantum optical experiments to the nanoscale and offers a promising route towards subwavelength quantum optical networks. PMID:23934097

  4. Interference in multilayer relativistic mirrors

    NASA Astrophysics Data System (ADS)

    Mirzanejhad, Saeed; Sohbatzadeh, Farshad; Babaei, Javad; Taghipour, Meisam; Mohammadzadeh, Zahra

    2015-10-01

    In this paper, reflection coefficient of a relativistic ultra-thin electron multilayer is calculated using electromagnetic interference procedures. The relativistic electron layers are assumed to be formed by nonlinear plasma wake waves that constitute the electron density cusps. It is shown that the interference between successive relativistic mirrors is restricted by the condition, τ p ≫ ( 2 γ 0 ) 5 / 2 / ω p 0 , where τp is the laser pulse duration. The results showed that tailoring the pulse amplitude, incident wave frequency value, incidence angle, and plasma density leads to increasing reflection coefficient a few orders of magnitudes. This constructive interference condition can be used for increasing conversion efficiency in the reflected energy from relativistic mirrors for the purpose of generating ultra-short coherence pulses in the extreme ultraviolet and x-ray regions. We also performed reflection from relativistic thin electron layers using relativistic 1D3V electromagnetic particle-in-cell (PIC) simulation. It was found that the results of PIC simulation are in agreement with analytical considerations.

  5. Oculomotor interference of bimodal distractors.

    PubMed

    Heeman, Jessica; Nijboer, Tanja C W; Van der Stoep, Nathan; Theeuwes, Jan; Van der Stigchel, Stefan

    2016-06-01

    When executing an eye movement to a target location, the presence of an irrelevant distracting stimulus can influence the saccade metrics and latency. The present study investigated the influence of distractors of different sensory modalities (i.e. auditory, visual and audiovisual) which were presented at various distances (i.e. close or remote) from a visual target. The interfering effects of a bimodal distractor were more pronounced in the spatial domain than in the temporal domain. The results indicate that the direction of interference depended on the spatial layout of the visual scene. The close bimodal distractor caused the saccade endpoint and saccade trajectory to deviate towards the distractor whereas the remote bimodal distractor caused a deviation away from the distractor. Furthermore, saccade averaging and trajectory deviation evoked by a bimodal distractor was larger compared to the effects evoked by a unimodal distractor. This indicates that a bimodal distractor evoked stronger spatial oculomotor competition compared to a unimodal distractor and that the direction of the interference depended on the distance between the target and the distractor. Together, these findings suggest that the oculomotor vector to irrelevant bimodal input is enhanced and that the interference by multisensory input is stronger compared to unisensory input. PMID:27164053

  6. Quantum interference in plasmonic circuits

    NASA Astrophysics Data System (ADS)

    Heeres, Reinier W.; Kouwenhoven, Leo P.; Zwiller, Valery

    2013-10-01

    Surface plasmon polaritons (plasmons) are a combination of light and a collective oscillation of the free electron plasma at metal/dielectric interfaces. This interaction allows subwavelength confinement of light beyond the diffraction limit inherent to dielectric structures. As a result, the intensity of the electromagnetic field is enhanced, with the possibility to increase the strength of the optical interactions between waveguides, light sources and detectors. Plasmons maintain non-classical photon statistics and preserve entanglement upon transmission through thin, patterned metallic films or weakly confining waveguides. For quantum applications, it is essential that plasmons behave as indistinguishable quantum particles. Here we report on a quantum interference experiment in a nanoscale plasmonic circuit consisting of an on-chip plasmon beamsplitter with integrated superconducting single-photon detectors to allow efficient single plasmon detection. We demonstrate a quantum-mechanical interaction between pairs of indistinguishable surface plasmons by observing Hong-Ou-Mandel (HOM) interference, a hallmark non-classical interference effect that is the basis of linear optics-based quantum computation. Our work shows that it is feasible to shrink quantum optical experiments to the nanoscale and offers a promising route towards subwavelength quantum optical networks.

  7. Cognitive interference can be mitigated by consonant music and facilitated by dissonant music

    PubMed Central

    Masataka, Nobuo; Perlovsky, Leonid

    2013-01-01

    Debates on the origins of consonance and dissonance in music have a long history. While some scientists argue that consonance judgments are an acquired competence based on exposure to the musical-system-specific knowledge of a particular culture, others favor a biological explanation for the observed preference for consonance. Here we provide experimental confirmation that this preference plays an adaptive role in human cognition: it reduces cognitive interference. The results of our experiment reveal that exposure to a Mozart minuet mitigates interference, whereas, conversely, when the music is modified to consist of mostly dissonant intervals the interference effect is intensified. PMID:23778307

  8. Cognitive interference can be mitigated by consonant music and facilitated by dissonant music.

    PubMed

    Masataka, Nobuo; Perlovsky, Leonid

    2013-01-01

    Debates on the origins of consonance and dissonance in music have a long history. While some scientists argue that consonance judgments are an acquired competence based on exposure to the musical-system-specific knowledge of a particular culture, others favor a biological explanation for the observed preference for consonance. Here we provide experimental confirmation that this preference plays an adaptive role in human cognition: it reduces cognitive interference. The results of our experiment reveal that exposure to a Mozart minuet mitigates interference, whereas, conversely, when the music is modified to consist of mostly dissonant intervals the interference effect is intensified. PMID:23778307

  9. Interference of Wing and Fuselage from Tests of 17 Combinations in the NACA Variable-density Tunnel Combination with Special Junctures

    NASA Technical Reports Server (NTRS)

    Sherman, Albert

    1938-01-01

    As part of the wing-fuselage interference program in progress in the NACA variable-density wind tunnel, a method of eliminating the interference bubble associated with critical mid wing combinations was investigated. The interference bubble of the critical mid wing combination was shown to respond to modification at the nose of the juncture and to be entirely suppressed with little or no adverse effect on the high-speed drag by special leading edge fillets.

  10. 49 CFR 193.2633 - Interference currents.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Interference currents. 193.2633 Section 193.2633...: FEDERAL SAFETY STANDARDS Maintenance § 193.2633 Interference currents. (a) Each component that is subject to electrical current interference must be protected by a continuing program to minimize...

  11. 49 CFR 193.2633 - Interference currents.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Interference currents. 193.2633 Section 193.2633...: FEDERAL SAFETY STANDARDS Maintenance § 193.2633 Interference currents. (a) Each component that is subject to electrical current interference must be protected by a continuing program to minimize...

  12. 49 CFR 193.2633 - Interference currents.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Interference currents. 193.2633 Section 193.2633...: FEDERAL SAFETY STANDARDS Maintenance § 193.2633 Interference currents. (a) Each component that is subject to electrical current interference must be protected by a continuing program to minimize...

  13. 49 CFR 193.2633 - Interference currents.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Interference currents. 193.2633 Section 193.2633...: FEDERAL SAFETY STANDARDS Maintenance § 193.2633 Interference currents. (a) Each component that is subject to electrical current interference must be protected by a continuing program to minimize...

  14. 49 CFR 193.2633 - Interference currents.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Interference currents. 193.2633 Section 193.2633...: FEDERAL SAFETY STANDARDS Maintenance § 193.2633 Interference currents. (a) Each component that is subject to electrical current interference must be protected by a continuing program to minimize...

  15. Radio Science Measurements with Suppressed Carrier

    NASA Technical Reports Server (NTRS)

    Asmar, Sami; Divsalar, Dariush; Oudrhiri, Kamal

    2013-01-01

    Radio Science started when it became apparent with early Solar missions that occultations by planetary atmospheres would affect the quality of radio communications. Since then the atmospheric properties and other aspects of planetary science, solar science, and fundamental physics were studied by scientists. Radio Science data was always extracted from a received pure residual carrier (without data modulation). For some missions, it is very desirable to obtain Radio Science data from a suppressed carrier modulation. In this paper we propose a method to extract Radio Science data when a coded suppressed carrier modulation is used in deep space communications. Type of modulation can be BPSK, QPSK, OQPSK, MPSK or even GMSK. However we concentrate mostly on BPSK modulation. The proposed method for suppressed carrier simply tries to wipe out data that acts as an interference for Radio Science measurements. In order to measure the estimation errors in amplitude and phase of the Radio Science data we use Cramer-Rao bound (CRB). The CRB for the suppressed carrier modulation with non-ideal data wiping is then compared with residual carrier modulation under the same noise condition. The method of derivation of CRB for non-ideal data wiping is an innovative method that presented here. Some numerical results are provided for coded system.

  16. Polyphosphate suppresses complement via the terminal pathway

    PubMed Central

    Wat, Jovian M.; Foley, Jonathan H.; Krisinger, Michael J.; Ocariza, Linnette Mae; Lei, Victor; Wasney, Gregory A.; Lameignere, Emilie; Strynadka, Natalie C.; Smith, Stephanie A.; Morrissey, James H.

    2014-01-01

    Polyphosphate, synthesized by all cells, is a linear polymer of inorganic phosphate. When released into the circulation, it exerts prothrombotic and proinflammatory activities by modulating steps in the coagulation cascade. We examined the role of polyphosphate in regulating the evolutionarily related proteolytic cascade complement. In erythrocyte lysis assays, polyphosphate comprising more than 1000 phosphate units suppressed total hemolytic activity with a concentration to reduce maximal lysis to 50% that was 10-fold lower than with monophosphate. In the ion- and enzyme-independent terminal pathway complement assay, polyphosphate suppressed complement in a concentration- and size-dependent manner. Phosphatase-treated polyphosphate lost its ability to suppress complement, confirming that polymer integrity is required. Sequential addition of polyphosphate to the terminal pathway assay showed that polyphosphate interferes with complement only when added before formation of the C5b-7 complex. Physicochemical analyses using native gels, gel filtration, and differential scanning fluorimetry revealed that polyphosphate binds to and destabilizes C5b,6, thereby reducing the capacity of the membrane attack complex to bind to and lyse the target cell. In summary, we have added another function to polyphosphate in blood, demonstrating that it dampens the innate immune response by suppressing complement. These findings further establish the complex relationship between coagulation and innate immunity. PMID:24335501

  17. Renormalization screening and collision-induced quantum interference in dense plasmas

    SciTech Connect

    Jung, Young-Dae; Rasheed, A.; Jamil, M.

    2014-07-15

    The influence of renormalization screening and collision-induced quantum interference in electron-electron collisions is investigated in partially ionized dense hydrogen plasmas. The effective interaction potential with the total spin-states of the collision system is considered to obtain the differential electron-electron scattering cross section. The results show that the renormalization plasma screening effect suppresses the electron-electron scattering cross section, including the quantum interference effect, especially, except for the forward and backward scattering directions. It is also shown that the renormalization plasma screening effect on the scattering cross section decreases with increasing collision energy. However, the renormalization screening effect is found to be important for the forward directions in the scattering cross section neglecting the quantum interference effect. The variations of the renormalization screening and collision-induced quantum interference effects are also discussed.

  18. Dissipative time-dependent quantum transport theory: Quantum interference and phonon induced decoherence dynamics

    SciTech Connect

    Zhang, Yu Chen, GuanHua; Yam, ChiYung

    2015-04-28

    A time-dependent inelastic electron transport theory for strong electron-phonon interaction is established via the equations of motion method combined with the small polaron transformation. In this work, the dissipation via electron-phonon coupling is taken into account in the strong coupling regime, which validates the small polaron transformation. The corresponding equations of motion are developed, which are used to study the quantum interference effect and phonon-induced decoherence dynamics in molecular junctions. Numerical studies show clearly quantum interference effect of the transport electrons through two quasi-degenerate states with different couplings to the leads. We also found that the quantum interference can be suppressed by the electron-phonon interaction where the phase coherence is destroyed by phonon scattering. This indicates the importance of electron-phonon interaction in systems with prominent quantum interference effect.

  19. A dedicated system for topographical working memory: evidence from domain-specific interference tests.

    PubMed

    Piccardi, L; Nori, R; Boccia, M; Barbetti, S; Verde, P; Guariglia, C; Ferlazzo, F

    2015-08-01

    In the present study, we used single- and dual-task conditions to investigate the nature of topographical working memory to better understand what type of task can hamper performance during navigation. During dual-task conditions, we considered four different sources of interference: motor (M), spatial motor (SM), verbal (i.e. articulatory suppression AS) and spatial environmental (SE). In order to assess the nature of topographical working memory, we used the Walking Corsi Test, asking the participants to perform two tasks simultaneously (M, SM, AS and SE). Our results showed that only spatial-environmental interference hampers the execution of a topographical working memory task, suggesting a task-domain-specific effect. We also found general gender differences in the topographical working memory capabilities: men were more proficient than women, regardless of the type of interferences. However, like men, women performed worse when a spatial-environmental interference was present. PMID:26003128

  20. Many-particle interference beyond many-boson and many-fermion statistics

    NASA Astrophysics Data System (ADS)

    Tichy, Malte C.; Tiersch, Markus; Mintert, Florian; Buchleitner, Andreas

    2012-09-01

    Identical particles exhibit correlations even in the absence of inter-particle interaction, due to the exchange (anti)symmetry of the many-particle wavefunction. Two fermions obey the Pauli principle and anti-bunch, whereas two bosons favor bunched, doubly occupied states. Here, we show that the collective interference of three or more particles leads to much more diverse behavior than expected from the boson-fermion dichotomy known from quantum statistical mechanics. The emerging complexity of many-particle interference is tamed by a simple law for the strict suppression of events in the Bell multiport beam splitter. The law shows that counting events are governed by widely species-independent interference, such that bosons and fermions can even exhibit identical interference signatures, while their statistical character remains subordinate. Recent progress in the preparation of tailored many-particle states of bosonic and fermionic atoms promises experimental verification and applications in novel many-particle interferometers.

  1. A hybrid method for strong low-frequency noise suppression in prestack seismic data

    NASA Astrophysics Data System (ADS)

    Hu, Chunhua; Lu, Wenkai

    2014-09-01

    Low-frequency components are important portion of seismic data in exploration geophysics, and have great effects on seismic imaging of deep subsurface and full waveform inversion. Unfortunately, seismic data usually suffers from various kinds of noises and has low signal to noise ratio (SNR) in low-frequency band, although this situation has been improved by developments of acquisition technology. In this paper, we propose a low-frequency cascade filter (LFCF) in Fourier domain for strong low-frequency noise suppression in prestack gathers. LFCF includes a 1D adaptive median filter in f-x domain and a 2D notch filter in f-k domain, which is able to process high-amplitude swell noise, random noise, and seismic interference noise. We employ traces rearrangement and spike-detection mechanisms in adaptive f-x median filter, which can handle strong noise specifically, such as wide-spreading swell noise and tug noise. And a notch filter in f-k domain is designed to separate reflection signal and random noise by different apparent velocities. Through these means, our method can effectively attenuate low-frequency random and coherent noise while simultaneously protect the signal. Experiments on synthetic example and field data are conducted, and the results demonstrate that our method is practical and effective and can preserve signal down to 2 Hz.

  2. Adaptive Management

    EPA Science Inventory

    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 managem...

  3. IIR filtering based adaptive active vibration control methodology with online secondary path modeling using PZT actuators

    NASA Astrophysics Data System (ADS)

    Boz, Utku; Basdogan, Ipek

    2015-12-01

    Structural vibrations is a major cause for noise problems, discomfort and mechanical failures in aerospace, automotive and marine systems, which are mainly composed of plate-like structures. In order to reduce structural vibrations on these structures, active vibration control (AVC) is an effective approach. Adaptive filtering methodologies are preferred in AVC due to their ability to adjust themselves for varying dynamics of the structure during the operation. The filtered-X LMS (FXLMS) algorithm is a simple adaptive filtering algorithm widely implemented in active control applications. Proper implementation of FXLMS requires availability of a reference signal to mimic the disturbance and model of the dynamics between the control actuator and the error sensor, namely the secondary path. However, the controller output could interfere with the reference signal and the secondary path dynamics may change during the operation. This interference problem can be resolved by using an infinite impulse response (IIR) filter which considers feedback of the one or more previous control signals to the controller output and the changing secondary path dynamics can be updated using an online modeling technique. In this paper, IIR filtering based filtered-U LMS (FULMS) controller is combined with online secondary path modeling algorithm to suppress the vibrations of a plate-like structure. The results are validated through numerical and experimental studies. The results show that the FULMS with online secondary path modeling approach has more vibration rejection capabilities with higher convergence rate than the FXLMS counterpart.

  4. Neural-Network Controller For Vibration Suppression

    NASA Technical Reports Server (NTRS)

    Boussalis, Dhemetrios; Wang, Shyh Jong

    1995-01-01

    Neural-network-based adaptive-control system proposed for vibration suppression of flexible space structures. Controller features three-layer neural network and utilizes output feedback. Measurements generated by various sensors on structure. Feed forward path also included to speed up response in case plant exhibits predominantly linear dynamic behavior. System applicable to single-input single-output systems. Work extended to multiple-input multiple-output systems as well.

  5. A Cognitive Framework for Understanding and Improving Interference Resolution in the Brain

    PubMed Central

    Mishra, Jyoti; Anguera, Joaquin A.; Ziegler, David A.; Gazzaley, Adam

    2014-01-01

    All of us are familiar with the negative impact of interference on achieving our task goals. We are referring to interference by information, which either impinges on our senses from an external environmental source or is internally generated by our thoughts. Informed by more than a decade of research on the cognitive and neural processing of interference, we have developed a framework for understanding how interference impacts our neural systems and especially how it is regulated and suppressed during efficient on-task performance. Importantly, externally and internally generated interferences have distinct neural signatures, and further, distinct neural processing emerges depending on whether individuals must ignore and suppress the interference, as for distractions, or engage with them in a secondary task, as during multitasking. Here, we elaborate on this cognitive framework and how it changes throughout the human lifespan, focusing mostly on research evidence from younger adults and comparing these findings to data from older adults, children, and cognitively impaired populations. With insights gleaned from our growing understanding, we then describe three novel translational efforts in our lab directed at improving distinct aspects of interference resolution using cognitive training. Critically, these training approaches were specifically developed to target improved interference resolution based on neuroplasticity principles and have shown much success in randomized controlled first version evaluations in healthy aging. Our results show not only on-task training improvements but also robust generalization of benefit to other cognitive control abilities. This research showcases how an in-depth understanding of neural mechanisms can then inform the development of effective deficit-targeted interventions, which can in turn benefit both healthy and cognitively impaired populations. PMID:24309262

  6. New cardiac MRI gating method using event-synchronous adaptive digital filter.

    PubMed

    Park, Hodong; Park, Youngcheol; Cho, Sungpil; Jang, Bongryoel; Lee, Kyoungjoung

    2009-11-01

    When imaging the heart using MRI, an artefact-free electrocardiograph (ECG) signal is not only important for monitoring the patient's heart activity but also essential for cardiac gating to reduce noise in MR images induced by moving organs. The fundamental problem in conventional ECG is the distortion induced by electromagnetic interference. Here, we propose an adaptive algorithm for the suppression of MR gradient artefacts (MRGAs) in ECG leads of a cardiac MRI gating system. We have modeled MRGAs by assuming a source of strong pulses used for dephasing the MR signal. The modeled MRGAs are rectangular pulse-like signals. We used an event-synchronous adaptive digital filter whose reference signal is synchronous to the gradient peaks of MRI. The event detection processor for the event-synchronous adaptive digital filter was implemented using the phase space method-a sort of topology mapping method-and least-squares acceleration filter. For evaluating the efficiency of the proposed method, the filter was tested using simulation and actual data. The proposed method requires a simple experimental setup that does not require extra hardware connections to obtain the reference signals of adaptive digital filter. The proposed algorithm was more effective than the multichannel approach. PMID:19644754

  7. Interference in astronomical speckle patterns

    NASA Technical Reports Server (NTRS)

    Breckinridge, J. B.

    1976-01-01

    Astronomical speckle patterns are examined in an atmospheric-optics context in order to determine what kind of image quality is to be expected from several different imaging techniques. The model used to describe the instantaneous complex field distribution across the pupil of a large telescope regards the pupil as a deep phase grating with a periodicity given by the size of the cell of uniform phase or the refractive index structure function. This model is used along with an empirical formula derived purely from the physical appearance of the speckle patterns to discuss the orders of interference in astronomical speckle patterns.

  8. Optical Path, Phase, and Interference

    NASA Astrophysics Data System (ADS)

    Newburgh, Ronald

    2005-11-01

    A powerful tool in wave optics is the concept of optical path length, a notion usually introduced with Fermat's principle.1-3 The analysis of Fermat's principle requires the application of the calculus of variations and the concept of an extremum, ideas too advanced for beginning students. However, the concept has proven its usefulness in the analysis4 of interference experiments such as those of Michelson and Fabry-Perot. In this paper we shall show how optical path length can aid in the analysis of a modified two-slit Young experiment.

  9. Long working distance interference microscope

    DOEpatents

    Sinclair, Michael B.; DeBoer, Maarten P.; Smith, Norman F.

    2004-04-13

    Disclosed is a long working distance interference microscope suitable for three-dimensional imaging and metrology of MEMS devices and test structures on a standard microelectronics probe station. The long working distance of 10-30 mm allows standard probes or probe cards to be used. This enables nanometer-scale 3-D height profiles of MEMS test structures to be acquired across an entire wafer. A well-matched pair of reference/sample objectives is not required, significantly reducing the cost of this microscope, as compared to a Linnik microinterferometer.

  10. A wall interference assessment/correction system

    NASA Technical Reports Server (NTRS)

    Lo, C. F.; Erickson, J. C.; Ulbrich, N.

    1991-01-01

    The Hackett method (a Wall Pressure Signature Method) was selected to be adapted for the 12 ft Wind Tunnel WIAC system. This method uses limited measurements of the static pressure at the wall, in conjunction with the solid wall boundary condition, to determine the strength and distribution of singularities representing the test article. The singularities are used in term for estimating wall interference at the model location. Hackett's method will have to be formulated for application to the unique geometry of the 12 ft tunnel. The WIAC code will be validated by conducting numerically simulated experiments rather than actual wind tunnel experiments. The simulations will be used to generate both free air and confined wind tunnel flow fields for each of the test articles over a range of test configurations. Specifically the pressure signature at the test section wall will be computed for the confined case to provide the simulated 'measured' data. These data will serve as the input for the WIAC method. The performance of the WIAC method then may be evaluated by comparing the corrected parameters with those for the free air simulation.

  11. Transcriptional interference among the murine β-like globin genes

    PubMed Central

    Hu, Xiao; Eszterhas, Susan; Pallazzi, Nicolas; Bouhassira, Eric E.; Fields, Jennifer; Tanabe, Osamu; Gerber, Scott A.; Bulger, Michael; Engel, James Douglas; Groudine, Mark

    2007-01-01

    Mammalian β-globin loci contain multiple genes that are activated at different developmental stages. Studies have suggested that the transcription of one gene in a locus can influence the expression of the other locus genes. The prevalent model to explain this transcriptional interference is that all potentially active genes compete for locus control region (LCR) activity. To investigate the influence of transcription by the murine embryonic genes on transcription of the other β-like genes, we generated mice with deletions of the promoter regions of Ey and βh1 and measured transcription of the remaining genes. Deletion of the Ey and βh1 promoters increased transcription of βmajor and βminor 2-fold to 3-fold during primitive erythropoiesis. Deletion of Ey did not affect βh1 nor did deletion of βh1 affect Ey, but Ey deletion uniquely activated transcription from βh0, a β-like globin gene immediately downstream of Ey. Protein analysis showed that βh0 encodes a translatable β-like globin protein that can pair with alpha globin. The lack of transcriptional interference between Ey and βh1 and the gene-specific repression of βh0 did not support LCR competition among the embryonic genes and suggested that direct transcriptional interference from Ey suppressed βh0. PMID:17077320

  12. Beamforming and interference canceling with very large wideband arrays

    NASA Astrophysics Data System (ADS)

    Ellingson, S. W.

    2003-06-01

    Future radio telescopes are envisioned to be beamforming arrays containing hundreds to millions of elements distributed over thousands of km2, with bandwidths that are 10% or more of the RF center frequency. It is awkward to analyze such systems using traditional narrowband beamforming theory. This paper presents a frequency-domain model that includes relevant features such as true time delay, distributed Doppler effects, and nonideal instrumental frequency response. Conventional beamforming - i.e., maximizing the gain in a certain direction subject to no other constraints - is analyzed in the context of the model. A simple method for suppressing interference in the beamformer output is also analyzed. In this method, a second beam is formed in the direction of the interference and subtracted from the output of the desired beam. Although the concept is sound, two problems are identified. First is the potential for partial or complete canceling of the desired source, along with the interference. The second problem is coloring of the noise spectrum, which may thwart the detection of weak spectral features. These problems are shown to be closely related to the array geometry, and some workarounds are suggested.

  13. Perceptual interference decays over short unfilled intervals.

    PubMed

    Schulkind, M D

    2000-09-01

    The perceptual interference effect refers to the fact that object identification is directly related to the amount of information available at initial exposure. The present article investigated whether perceptual interference would dissipate when a short, unfilled interval was introduced between exposures to a degraded object. Across three experiments using both musical and pictorial stimuli, identification performance increased directly with the length of the unfilled interval. Consequently, significant perceptual interference was obtained only when the interval between exposures was relatively short (< 500 msec for melodies; < 300 msec for pictures). These results are consistent with explanations that attribute perceptual interference to increased perceptual noise created by exposures to highly degraded objects. The data also suggest that perceptual interference is mediated by systems that are not consciously controlled by the subject and that perceptual interference in the visual domain decays more rapidly than perceptual interference in the auditory domain. PMID:11105520

  14. Interferences in automated phenol red method for determination of bromide in water

    USGS Publications Warehouse

    Basel, C.L.; Defreese, J.D.; Whittemore, D.O.

    1982-01-01

    The phenol red method for the determination of bromide in water has been automated by segmented flow analysis. Samples can be analyzed at a rate of 20 samples/h with a method detection limit, defined, as the concentration giving a signal about three times the standard deviation of replicate anaiyte determinations in reagent water, of 10 ??g/L. Samples studied include oil-field brines, halite solution brines, ground-waters contaminated with these brines, and fresh groundwaters. Chloride and bicarbonate cause significant positive interferences at levels as low as 100 mg/L and 50 mg/L, respectively. Ammonia gives a negative interference that is important at levels as low as 0.05 mg/L. An ionic strength buffer is used to suppress a positive ionic strength interference, correction curves are used to compensate for the chloride interference, the bicarbonate interference is minimized by acidification, and the ammonia interference is eliminated by its removal by ion exchange. Reaction product studies are used to suggest a plausible mode of chloride interference. ?? 1982 American Chemical Society.

  15. Selenite suppression of cadmium-induced testicular apoptosis.

    PubMed

    Jones, M M; Xu, C; Ladd, P A

    1997-01-15

    The characteristic apoptotic ladder-like patterns of rat testicular DNA on agarose gel electrophoresis which results from treatment with CdCl2 are suppressed by the administration of Na2SeO3. The examination of testicular tissue using an ELISA programmed cell death detection procedure confirmed this selenite suppression of cadmium-induced apoptosis. The administration of the Na2SeO3 at either 0.5, 1, 2 h prior to or 0.5, 1, 2 h after the administration of the CdCl2 appear to be almost equally effective at suppressing the apoptotic response. These results are in accord with previous studies on the Na2SeO3 suppression of cadmium induced necrotic changes in tissues and suggest that Na2SeO3 interferes with both necrosis and apoptosis. PMID:9020518

  16. The role of the left head of caudate in suppressing irrelevant words.

    PubMed

    Ali, Nilufa; Green, David W; Kherif, Ferath; Devlin, Joseph T; Price, Cathy J

    2010-10-01

    Suppressing irrelevant words is essential to successful speech production and is expected to involve general control mechanisms that reduce interference from task-unrelated processing. To investigate the neural mechanisms that suppress visual word interference, we used fMRI and a Stroop task, using a block design with an event-related analysis. Participants indicated with a finger press whether a visual stimulus was colored pink or blue. The stimulus was either the written word "BLUE," the written word "PINK," or a string of four Xs, with word interference introduced when the meaning of the word and its color were "incongruent" (e.g., BLUE in pink hue) relative to congruent (e.g., BLUE in blue) or neutral (e.g., XXXX in pink). The participants also made color decisions in the presence of spatial interference rather than word interference (i.e., the Simon task). By blocking incongruent, congruent, and neutral trials, we identified activation related to the mechanisms that suppress interference as that which was greater at the end relative to the start of incongruency. This highlighted the role of the left head of caudate in the control of word interference but not spatial interference. The response in the left head of caudate contrasted to bilateral inferior frontal activation that was greater at the start than at the end of incongruency, and to the dorsal anterior cingulate gyrus which responded to a change in the motor response. Our study therefore provides novel insights into the role of the left head of caudate in the mechanisms that suppress word interference. PMID:19803688

  17. The challenge of adaptive structures

    NASA Astrophysics Data System (ADS)

    Breitbach, E. J.; Wimmel, R.

    Future lightweight design in space structure technology has to pay more attention to vibration suppression, to position control, or, more generally, to structure-inherent adaptability. These properties are often called "intelligent" or "smart", ignoring the fact that only creatures can have mental abilities. Having adaptation mechanisms for every dynamic process, living nature indeed teaches us that it is inexpedient if technical structural systems dispense with adaptability. Vibration and stability phenomena are making performance restrictions in space systems more and more evident. The DLR project ARES (Actively Reacting Flexible Structures) intends to overcome these limitations by developing a new class of technical systems. The ARES concept essentially consists of two new technologies: new kinds of integrated sensors and actuators working as components lying in the structural load path, and adaptive controllers consisting of digital filters which are adaptive in that they react against changing environmental influences as well as changes within the structure itself.

  18. Familiarity interferes with filial imprinting.

    PubMed

    van Kampen, H S; de Vos, G J

    1996-10-01

    The present study was performed to investigate whether and how pre-exposure to an object affects subsequent filial imprinting to that object. In Experiment 1 junglefowl chicks (Gallus gallus spadiceus) were first exposed to either a red object alone (control group), or a red and a yellow object simultaneously (experimental group; phase 1). Subsequently, all chicks were exposed to the yellow object in the presence of a black and blue one (phase 2). At the end of phase 1, most experimental chicks had developed a preference for the red object over the yellow one. At the end of phase 2, preferences of experimental chicks were shifted away from the yellow object towards the novel black and blue object, relative to preferences of control chicks. This shows that pre-exposure may interfere with imprinting. Experiment 2 revealed that when control chicks were tested with the yellow object at the end of phase 1, filial responses were as strong as in experimental chicks. This shows that the yellow object had not acquired control over filial behaviour during phase 1, and also that the relatively impaired imprinting on that object in phase 2 was not due to reduced generalization from the red object. One possible explanation why pre-exposure may interfere with imprinting is that familiarity alters the level of attention attracted by an object, a mechanism suggested to underlie 'latent inhibition' in conditioning. PMID:24897630

  19. Motor interference in interactive contexts.

    PubMed

    Chinellato, Eris; Castiello, Umberto; Sartori, Luisa

    2015-01-01

    Action observation and execution share overlapping neural substrates, so that simultaneous activation by observation and execution modulates motor performance. Previous literature on simple prehension tasks has revealed that motor influence can be two-sided: facilitation for observed and performed congruent actions and interference for incongruent actions. But little is known of the specific modulations of motor performance in complex forms of interaction. Is it possible that the very same observed movement can lead either to interference or facilitation effects on a temporally overlapping congruent executed action, depending on the context? To answer this question participants were asked to perform a reach-to-grasp movement adopting a precision grip (PG) while: (i) observing a fixation cross, (ii) observing an actor performing a PG with interactive purposes, (iii) observing an actor performing a PG without interactive purposes. In particular, in the interactive condition the actor was shown trying to pour some sugar on a large cup located out of her reach but close to the participant watching the video, thus eliciting in reaction a complementary whole-hand grasp. Notably, fine-grained kinematic analysis for this condition revealed a specific delay in the grasping and reaching components and an increased trajectory deviation despite the observed and executed movement's congruency. Moreover, early peaks of trajectory deviation seem to indicate that socially relevant stimuli are acknowledged by the motor system very early. These data suggest that interactive contexts can determine a prompt modulation of stimulus-response compatibility effects. PMID:26113835

  20. Cough suppression disorders spectrum.

    PubMed

    Reich, Jerome M

    2014-02-01

    Volitional cough suppression, identified exclusively in females, is an unusual causal mechanism for instances of lobar atalectasis and bronchiectasis. It is a postulated mechanism for the genesis of Lady Windermere Syndrome. PMID:24462261

  1. Jet Noise Suppression

    NASA Technical Reports Server (NTRS)

    Gliebe, P. R.; Brausch, J. F.; Majjigi, R. K.; Lee, R.

    1991-01-01

    The objectives of this chapter are to review and summarize the jet noise suppression technology, to provide a physical and theoretical model to explain the measured jet noise suppression characteristics of different concepts, and to provide a set of guidelines for evolving jet noise suppression designs. The underlying principle for all jet noise suppression devices is to enhance rapid mixing (i.e., diffusion) of the jet plume by geometric and aerothermodynamic means. In the case of supersonic jets, the shock-cell broadband noise reduction is effectively accomplished by the elimination or mitigation of the shock-cell structure. So far, the diffusion concepts have predominantly concentrated on jet momentum and energy (kinetic and thermal) diffusion, in that order, and have yielded better noise reduction than the simple conical nozzles. A critical technology issue that needs resolution is the effect of flight on the noise suppression potential of mechanical suppressor nozzles. A more thorough investigation of this mechanism is necessary for the successful development and design of an acceptable noise suppression device for future high-speed civil transports.

  2. Thermopower signatures and spectroscopy of the canyon of conductance suppression

    NASA Astrophysics Data System (ADS)

    Kiršanskas, G.; Hammarberg, S.; Karlström, O.; Wacker, A.

    2016-07-01

    Interference effects in quantum dots between different transport channels can lead to a strong suppression of conductance, which cuts like a canyon through the common conductance plot [Phys. Rev. Lett. 104, 186804 (2010), 10.1103/PhysRevLett.104.186804]. In the present work we consider the thermoelectric transport properties of the canyon of conductance suppression using the second-order von Neumann approach. We observe a characteristic signal for the zeros of the thermopower. This demonstrates that thermoelectric measurements are an interesting complimentary tool to study complex phenomena for transport through confined systems.

  3. Null steering of adaptive beamforming using linear constraint minimum variance assisted by particle swarm optimization, dynamic mutated artificial immune system, and gravitational search algorithm.

    PubMed

    Darzi, Soodabeh; Kiong, Tiong Sieh; Islam, Mohammad Tariqul; Ismail, Mahamod; Kibria, Salehin; Salem, Balasem

    2014-01-01

    Linear constraint minimum variance (LCMV) is one of the adaptive beamforming techniques that is commonly applied to cancel interfering signals and steer or produce a strong beam to the desired signal through its computed weight vectors. However, weights computed by LCMV usually are not able to form the radiation beam towards the target user precisely and not good enough to reduce the interference by placing null at the interference sources. It is difficult to improve and optimize the LCMV beamforming technique through conventional empirical approach. To provide a solution to this problem, artificial intelligence (AI) technique is explored in order to enhance the LCMV beamforming ability. In this paper, particle swarm optimization (PSO), dynamic mutated artificial immune system (DM-AIS), and gravitational search algorithm (GSA) are incorporated into the existing LCMV technique in order to improve the weights of LCMV. The simulation result demonstrates that received signal to interference and noise ratio (SINR) of target user can be significantly improved by the integration of PSO, DM-AIS, and GSA in LCMV through the suppression of interference in undesired direction. Furthermore, the proposed GSA can be applied as a more effective technique in LCMV beamforming optimization as compared to the PSO technique. The algorithms were implemented using Matlab program. PMID:25147859

  4. Null Steering of Adaptive Beamforming Using Linear Constraint Minimum Variance Assisted by Particle Swarm Optimization, Dynamic Mutated Artificial Immune System, and Gravitational Search Algorithm

    PubMed Central

    Sieh Kiong, Tiong; Tariqul Islam, Mohammad; Ismail, Mahamod; Salem, Balasem

    2014-01-01

    Linear constraint minimum variance (LCMV) is one of the adaptive beamforming techniques that is commonly applied to cancel interfering signals and steer or produce a strong beam to the desired signal through its computed weight vectors. However, weights computed by LCMV usually are not able to form the radiation beam towards the target user precisely and not good enough to reduce the interference by placing null at the interference sources. It is difficult to improve and optimize the LCMV beamforming technique through conventional empirical approach. To provide a solution to this problem, artificial intelligence (AI) technique is explored in order to enhance the LCMV beamforming ability. In this paper, particle swarm optimization (PSO), dynamic mutated artificial immune system (DM-AIS), and gravitational search algorithm (GSA) are incorporated into the existing LCMV technique in order to improve the weights of LCMV. The simulation result demonstrates that received signal to interference and noise ratio (SINR) of target user can be significantly improved by the integration of PSO, DM-AIS, and GSA in LCMV through the suppression of interference in undesired direction. Furthermore, the proposed GSA can be applied as a more effective technique in LCMV beamforming optimization as compared to the PSO technique. The algorithms were implemented using Matlab program. PMID:25147859

  5. Adaptive SPECT

    PubMed Central

    Barrett, Harrison H.; Furenlid, Lars R.; Freed, Melanie; Hesterman, Jacob Y.; Kupinski, Matthew A.; Clarkson, Eric; Whitaker, Meredith K.

    2008-01-01

    Adaptive imaging systems alter their data-acquisition configuration or protocol in response to the image information received. An adaptive pinhole single-photon emission computed tomography (SPECT) system might acquire an initial scout image to obtain preliminary information about the radiotracer distribution and then adjust the configuration or sizes of the pinholes, the magnifications, or the projection angles in order to improve performance. This paper briefly describes two small-animal SPECT systems that allow this flexibility and then presents a framework for evaluating adaptive systems in general, and adaptive SPECT systems in particular. The evaluation is in terms of the performance of linear observers on detection or estimation tasks. Expressions are derived for the ideal linear (Hotelling) observer and the ideal linear (Wiener) estimator with adaptive imaging. Detailed expressions for the performance figures of merit are given, and possible adaptation rules are discussed. PMID:18541485

  6. Spatial light interference tomography (SLIT).

    PubMed

    Wang, Zhuo; Marks, Daniel L; Carney, Paul Scott; Millet, Larry J; Gillette, Martha U; Mihi, Agustin; Braun, Paul V; Shen, Zhen; Prasanth, Supriya G; Popescu, Gabriel

    2011-10-10

    We present spatial light interference tomography (SLIT), a label-free method for 3D imaging of transparent structures such as live cells. SLIT uses the principle of interferometric imaging with broadband fields and combines the optical gating due to the micron-scale coherence length with that of the high numerical aperture objective lens. Measuring the phase shift map associated with the object as it is translated through focus provides full information about the 3D distribution associated with the refractive index. Using a reconstruction algorithm based on the Born approximation, we show that the sample structure may be recovered via a 3D, complex field deconvolution. We illustrate the method with reconstructed tomographic refractive index distributions of microspheres, photonic crystals, and unstained living cells. PMID:21996999

  7. Quasiparticle interference from magnetic impurities

    NASA Astrophysics Data System (ADS)

    Derry, Philip G.; Mitchell, Andrew K.; Logan, David E.

    2015-07-01

    Fourier transform scanning tunneling spectroscopy (FT-STS) measures the scattering of conduction electrons from impurities and defects, giving information about the electronic structure of both the host material and adsorbed impurities. We interpret such FT-STS measurements in terms of the quasiparticle interference (QPI), here investigating in detail the QPI due to single magnetic impurities adsorbed on a range of representative nonmagnetic host surfaces, and contrasting with the case of a simple scalar impurity or point defect. We demonstrate how the electronic correlations present for magnetic impurities markedly affect the QPI, showing, e.g., a large intensity enhancement due to the Kondo effect, and universality at low temperatures/scanning energies. The commonly used joint density of states interpretation of FT-STS measurements is also considered, and shown to be insufficient in many cases, including that of magnetic impurities.

  8. Graphene Superconducting Quantum Interference Device

    NASA Astrophysics Data System (ADS)

    Girit, Çaǧlar; Bouchiat, Vincent; Naaman, Ofer; Zhang, Yuanbo; Crommie, Michael; Zettl, Alex; Siddiqi, Irfan

    2010-03-01

    Graphene can support Cooper pair transport when contacted with two superconducting electrodes, resulting in the well-known Josephson effect. By depositing aluminum/palladium electrodes in the geometry of a loop onto a single graphene sheet, we fabricate a two junction dc superconducting quantum interference device (SQUID). Not only an the supercurrent in this device be increased by moving the electrostatic gate away from the Dirac point, but it can also be modulated periodically by an applied magnetic field---a potentially powerful probe of electronic transport in graphene. We analyze the magnetic field modulation of the critical current with the asymmetric/inductive SQUID model of Fulton and Dynes and discuss the variation of the fitting parameters with gate voltage.

  9. Filtering algorithm for dotted interferences

    NASA Astrophysics Data System (ADS)

    Osterloh, K.; Bücherl, T.; Lierse von Gostomski, Ch.; Zscherpel, U.; Ewert, U.; Bock, S.

    2011-09-01

    An algorithm has been developed to remove reliably dotted interferences impairing the perceptibility of objects within a radiographic image. This particularly is a major challenge encountered with neutron radiographs collected at the NECTAR facility, Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II): the resulting images are dominated by features resembling a snow flurry. These artefacts are caused by scattered neutrons, gamma radiation, cosmic radiation, etc. all hitting the detector CCD directly in spite of a sophisticated shielding. This makes such images rather useless for further direct evaluations. One approach to resolve this problem of these random effects would be to collect a vast number of single images, to combine them appropriately and to process them with common image filtering procedures. However, it has been shown that, e.g. median filtering, depending on the kernel size in the plane and/or the number of single shots to be combined, is either insufficient or tends to blur sharp lined structures. This inevitably makes a visually controlled processing image by image unavoidable. Particularly in tomographic studies, it would be by far too tedious to treat each single projection by this way. Alternatively, it would be not only more comfortable but also in many cases the only reasonable approach to filter a stack of images in a batch procedure to get rid of the disturbing interferences. The algorithm presented here meets all these requirements. It reliably frees the images from the snowy pattern described above without the loss of fine structures and without a general blurring of the image. It consists of an iterative, within a batch procedure parameter free filtering algorithm aiming to eliminate the often complex interfering artefacts while leaving the original information untouched as far as possible.

  10. Coping with Radio Frequency Interference

    NASA Astrophysics Data System (ADS)

    Lewis, B. M.

    2009-01-01

    The radio spectrum is a finite resource, on which humanity makes many demands. And pressure on it is ever increasing with the development of new technology and ideas for radio services. After all, we all benefit from wifi and cell phones. Radio astronomers have a small percentage of the spectrum allocated to them at octave intervals in the metre-centimetre bands, and at important frequencies, such as that of the 21cm line of HI. Signals from other services, as well as from our own poorly-engineered equipment, sometimes contaminate our bands: these signals constitute RFI. These may totally obliterate the astronomical signal, or, in the case of CLOUDSAT, may be capable of completely destroying a receiver, which introduces us to the new possibility of 'destructive interference'. A geo-stationary satellite can block access to a piece of sky from one site. Good equipment design eliminates self-inflicted interference, while physical separation often provides adequate practical mitigation at many frequencies. However, new observatories end up being located in the West Australian desert or Antarctica. In future they may be on the back side of the Moon. But there is no Earth-bound protection via physical separation against satellite signals. Some mitigation can be achieved by frequent data dumps and the excision of RFI, or by real-time detection and blanking of the receiver, or by more sophisticated algoriths. Astronomers of necessity aim to achieve mitigation via coordination, at the local level, and by participating in spectrum management at the national and international levels. This involves them spending a lot of time in Geneva at the International Telegraphic Union protecting their access to spectrum, and access to clean spectrum from the L3 point and the far side of the Moon.

  11. CDMA with interference cancellation for multiprobe missions

    NASA Technical Reports Server (NTRS)

    Divsalar, D.; Simon, M. K.

    1995-01-01

    Code division multiple-access spread spectrum has been proposed for use in future multiprobe/multispacecraft missions. This article considers a general parallel interference-cancellation scheme that significantly reduces the degradation effect of probe (user) interference but with a lesser implementation complexity than the maximum-likelihood technique. The scheme operates on the fact that parallel processing simultaneously removes from each probe (user) the total interference produced by the remaining most reliably received probes (users) accessing the channel. The parallel processing can be done in multiple stages. The proposed scheme uses tentative decision devices with different optimum thresholds at the multiple stages to produce the most reliably received data for generation and cancellation of probe/spacecraft interference. The one-stage interference cancellation was analyzed for two types of tentative decision devices, namely, hard and null zone decisions. Simulation results are given for one- and two-stage interference cancellation for equal as well as unequal received power probes.

  12. Effects of additional interfering signals on adaptive array performance

    NASA Technical Reports Server (NTRS)

    Moses, Randolph L.

    1989-01-01

    The effects of additional interference signals on the performance of a fully adaptive array are considered. The case where the number of interference signals exceeds the number of array degrees of freedom is addressed. It is shown how performance is affected as a function of the number of array elements, the number of interference signals, and the directivity of the array antennas. By using directive auxiliary elements, the performance of the array can be as good as the performance when the additional interference signals are not present.

  13. Hyperspectral imaging camera using wavefront division interference.

    PubMed

    Bahalul, Eran; Bronfeld, Asaf; Epshtein, Shlomi; Saban, Yoram; Karsenty, Avi; Arieli, Yoel

    2016-03-01

    An approach for performing hyperspectral imaging is introduced. The hyperspectral imaging is based on Fourier transform spectroscopy, where the interference is performed by wavefront division interference rather than amplitude division interference. A variable phase delay between two parts of the wavefront emanating from each point of an object is created by a spatial light modulator (SLM) to obtain variable interference patterns. The SLM is placed in the exit pupil of an imaging system, thus enabling conversion of a general imaging optical system into an imaging hyperspectral optical system. The physical basis of the new approach is introduced, and an optical apparatus is built. PMID:26974085

  14. Three-slit interference: A duality relation

    NASA Astrophysics Data System (ADS)

    Asad Siddiqui, Mohd; Qureshi, Tabish

    2015-08-01

    The issue of interference and which-way information is addressed in the context of three-slit interference experiments. A new path distinguishability DQ is introduced, based on unambiguous quantum state discrimination. An inequality connecting the interference visibility and path distinguishability, V + {2D_Qover 3- D_Q} ≤ 1, is derived which puts a bound on how much fringe visibility and which-way information can be simultaneously obtained. It is argued that this bound is tight. For two-slit interference, we derive a new duality relation which reduces to Englert's duality relation and the Greenberger-Yasin duality relation, in different limits.

  15. The perirhinal cortex and recognition memory interference

    PubMed Central

    Watson, H.C.; Lee, A. C. H.

    2013-01-01

    There has recently been an increase in interest in the effects of visual interference on memory processing, with the aim of eluciating the role of the perirhinal cortex (PRC) in recognition memory. One view argues that the PRC processes highly complex conjunctions of object features, and recent evidence from rodents suggests that these representations may be vital for buffering against the effects of pre-retrieval interference on object recognition memory. To investigate whether PRC-dependent object representations play a similar role in humans, we used functional magnetic resonance imaging to scan neurologically healthy participants while they carried out a novel interference-match-to-sample task. This paradigm was specifically designed to concurrently assess the impact of object vs. spatial interference, on recognition memory for objects or scenes, while keeping constant the amount of object and scene information presented across all trials. Activity at retrieval was examined, within an anatomically defined PRC region of interest, according to the demand for object or scene memory, following a period of object compared to spatial interference. Critically, we found greater PRC activity for object memory following object interference, compared to object memory following scene interference, and no difference between object and scene interference for scene recognition. These data demonstrate a role for the human PRC following a period of object, but not scene, interference, during object recognition memory, and emphasize the importance of representational content to mnemonic processing. PMID:23447626

  16. Radio frequency selection and interference prevention

    NASA Technical Reports Server (NTRS)

    Degroot, N. F.

    1982-01-01

    The bands available for deep-space communications, and the choice of particular mission frequencies are discussed. The more general susceptibility of deep-space Earth stations to various kinds of interference is then presented. An associated topic is the development of protection criteria that specify maximum allowable levels of interference. Next, the prediction of interference from near-Earth satellites is described, with particular emphasis on the problems and uncertainties of such predictions. Finally, a brief description of other activities aimed at the prevention or avoidance of interference to deep-space radio communications is given.

  17. Programmable two-photon quantum interference in 103 channels in opaque scattering media

    NASA Astrophysics Data System (ADS)

    Wolterink, Tom A. W.; Uppu, Ravitej; Ctistis, Georgios; Vos, Willem L.; Boller, Klaus-J.; Pinkse, Pepijn W. H.

    2016-05-01

    We investigate two-photon quantum interference in an opaque scattering medium that intrinsically supports a large number of transmission channels. By adaptive spatial phase modulation of the incident wave fronts, the photons are directed at targeted speckle spots or output channels. From 103 experimentally available coupled channels, we select two channels and enhance their transmission to realize the equivalent of a fully programmable 2 ×2 beam splitter. By sending pairs of single photons from a parametric down-conversion source through the opaque scattering medium, we observe two-photon quantum interference. The programed beam splitter need not fulfill energy conservation over the two selected output channels and hence could be nonunitary. Consequently, we have the freedom to tune the quantum interference from bunching (Hong-Ou-Mandel-like) to antibunching. Our results establish opaque scattering media as a platform for high-dimensional quantum interference that is notably relevant for boson sampling and physical-key-based authentication.

  18. Anodal motor cortex stimulation paired with movement repetition increases anterograde interference but not savings.

    PubMed

    Leow, Li-Ann; Hammond, Geoff; de Rugy, Aymar

    2014-10-01

    Retention of motor adaptation is evident in savings, where initial learning improves subsequent learning, and anterograde interference, where initial learning impairs subsequent learning. Previously, we proposed that use-dependent movement biases induced by movement repetition contribute to anterograde interference, but not to savings. Here, we evaluate this proposal by limiting or extending movement repetition while stimulating the motor cortex (M1) with anodal transcranial direct current stimulation (tDCS), a brain stimulation technique known to increase use-dependent plasticity when applied during movement repetition. Participants first adapted to a counterclockwise rotation of visual feedback imposed either abruptly (extended repetition) or gradually (limited repetition) in a first block (A1), during which either sham or anodal tDCS (2 mA) was applied over M1. Anterograde interference was then assessed in a second block (B) with a clockwise rotation, and savings in a third block (A2) with a counterclockwise rotation. Anodal M1 tDCS elicited more anterograde interference than sham stimulation with extended but not with limited movement repetition. Conversely, anodal M1 tDCS did not affect savings with either limited or extended repetition of the adapted movement. Crucially, the effect of anodal M1 tDCS on anterograde interference did not require large errors evoked by an abrupt perturbation schedule, as anodal M1 tDCS combined with extended movement repetition within a gradual perturbation schedule similarly increased anterograde interference but not savings. These findings demonstrate that use-dependent plasticity contributes to anterograde interference but not to savings. PMID:25160706

  19. Spectrum recovery method analysis on nonuniform sampling interference data

    NASA Astrophysics Data System (ADS)

    Huang, Fengzhen; Li, Jingzhen; Cao, Jun

    2015-02-01

    Temporally and Spatially Modulated Fourier Transform Imaging Spectrometer (TSMFTIS) is a new imaging spectrometer without moving mirrors and slits. The interferogram of the target point can be consisted by sequentially arranging the interference information extracted from the same target point of the sequential images, and the spectrum can be recovered by using fast Fourier transform. In the practical application, there is nonuniform sampling in the interference data, and many researchers have carried out researches on nonuniform sampling with the fast Fourier transform algorithm. As to the issue of interference data in the nonuniform sampling, the nonuniform sampling degree's impact on the recovered spectrum precision is currently and mainly analyzed. This paper has adapted several typical nonuniform fast Fourier transform (NUFFT) methods, carried out spectrum recovery precision comparison on the interferogram of the nonuniform sampling point with the above methods, and further analyzed the impact of kernel function type, oversampling ratio and kernel function width's on spectrum recovery precision in the above mentioned methods. The experiment result indicates that, when the oversampling ratio is 4 and the kernel function width is 4, the spectrum recovery precision with NUFFT based on Blackman type kernel function is optimal, however, the Gaussian kernel function is stable.

  20. Shock interference studies on a circular cylinder at Mach 16

    NASA Technical Reports Server (NTRS)

    Prabhu, Ramadas K.; Thareja, Rajiv R.; Stewart, James R.

    1990-01-01

    This paper presents the results of a computational study on the shock interference problems on a cylindrical body typical of an engine inlet cowl leading edge at a nominal Mach number of 16. The two-dimensional Navier-Stokes equations are solved assuming the flow to be in chemical and thermal equilibrium and using a finite element method. The algorithm employs a cell-centered fully implicit upwind scheme. Adaptively generated unstructured meshes of triangles and quadrilaterals are employed. Under certain conditions the finite element code resulted in oscillatory solutions for shock interference at Mach 16. Some of the causes of the unsteady behavior are identified, and to the extent possible, such situations are avoided in the present application. Two shock interference conditions involving a Type IV (supersonic jet) and a Type III (attaching shear layer) are solved. The results are compared with available experimental data and reasonable agreement is observed. A semi-empirical method is also used to estimate the maximum surface heat flux and static pressure.

  1. Explosion suppression system

    DOEpatents

    Sapko, Michael J.; Cortese, Robert A.

    1992-01-01

    An explosion suppression system and triggering apparatus therefor are provided for quenching gas and dust explosions. An electrically actuated suppression mechanism which dispenses an extinguishing agent into the path ahead of the propagating flame is actuated by a triggering device which is light powered. This triggering device is located upstream of the propagating flame and converts light from the flame to an electrical actuation signal. A pressure arming device electrically connects the triggering device to the suppression device only when the explosion is sensed by a further characteristic thereof beside the flame such as the pioneer pressure wave. The light powered triggering device includes a solar panel which is disposed in the path of the explosion and oriented between horizontally downward and vertical. Testing mechanisms are also preferably provided to test the operation of the solar panel and detonator as well as the pressure arming mechanism.

  2. Suppression of Odorant Responses by Odorants in Olfactory Receptor Cells

    NASA Astrophysics Data System (ADS)

    Kurahashi, Takashi; Lowe, Graeme; Gold, Geoffrey H.

    1994-07-01

    Odorants activate an inward current in vertebrate olfactory receptor cells. Here it is shown, in receptor cells from the newt, that odorants can also suppress this current, by a mechanism that is distinct from inhibition and adaptation. Suppression provides a simple explanation for two seemingly unrelated phenomena: the anomalously long latency of olfactory transduction and the existence of an "off response" at the end of a prolonged stimulus. Suppression may influence the perception of odorants by masking odorant responses and by sharpening the odorant specificities of single cells.

  3. Repetition suppression and its contextual determinants in predictive coding.

    PubMed

    Auksztulewicz, Ryszard; Friston, Karl

    2016-07-01

    This paper presents a review of theoretical and empirical work on repetition suppression in the context of predictive coding. Predictive coding is a neurobiologically plausible scheme explaining how biological systems might perform perceptual inference and learning. From this perspective, repetition suppression is a manifestation of minimising prediction error through adaptive changes in predictions about the content and precision of sensory inputs. Simulations of artificial neural hierarchies provide a principled way of understanding how repetition suppression - at different time scales - can be explained in terms of inference and learning implemented under predictive coding. This formulation of repetition suppression is supported by results of numerous empirical studies of repetition suppression and its contextual determinants. PMID:26861557

  4. Ambroxol interferes with Pseudomonas aeruginosa quorum sensing.

    PubMed

    Lu, Qi; Yu, Jialin; Yang, Xiqiang; Wang, Jiarong; Wang, Lijia; Lin, Yayin; Lin, Lihua

    2010-09-01

    The mucolytic agent ambroxol has been reported to interfere with the formation of Pseudomonas aeruginosa-derived biofilms in addition to reducing alginate production by undefined mechanisms. Since quorum sensing is a key regulator of virulence and biofilm formation, we examined the effects of ambroxol on P. aeruginosa PAO1 wild-type bacterial clearance rates, adhesion profiles and biofilm formation compared with the quorum sensing-deficient, double-mutant strains DeltalasR DeltarhlR and DeltalasI DeltarhlI. Data presented in this report demonstrated that ambroxol treatment reduced survival rates of the double-mutant strains compared with the wild-type strain in a dose-dependent manner even though the double-mutants had increased adhesion in the presence of ambroxol compared with the wild-type strain. The PAO1 wild-type strain produced a significantly thicker biofilm (21.64+/-0.57 microm) compared with the biofilms produced by the DeltalasR DeltarhlR (7.36+/-0.2 microm) and DeltalasI DeltarhlI (6.62+/-0.31 microm) isolates. Ambroxol treatment reduced biofilm thickness, increased areal porosity, and decreased the average diffusion distance and textual entropy of wild-type and double-mutant strains. However, compared with the double-mutant strains, the changes observed for the wild-type strain were more clearly defined. Finally, ambroxol exhibited significant antagonistic quorum-sensing properties, suggesting that it could be adapted for use clinically in the treatment of cystic fibrosis and to reduce biofilm formation and in the colonisation of indwelling devices. PMID:20580207

  5. A Rapid Convergent Low Complexity Interference Alignment Algorithm for Wireless Sensor Networks

    PubMed Central

    Jiang, Lihui; Wu, Zhilu; Ren, Guanghui; Wang, Gangyi; Zhao, Nan

    2015-01-01

    Interference alignment (IA) is a novel technique that can effectively eliminate the interference and approach the sum capacity of wireless sensor networks (WSNs) when the signal-to-noise ratio (SNR) is high, by casting the desired signal and interference into different signal subspaces. The traditional alternating minimization interference leakage (AMIL) algorithm for IA shows good performance in high SNR regimes, however, the complexity of the AMIL algorithm increases dramatically as the number of users and antennas increases, posing limits to its applications in the practical systems. In this paper, a novel IA algorithm, called directional quartic optimal (DQO) algorithm, is proposed to minimize the interference leakage with rapid convergence and low complexity. The properties of the AMIL algorithm are investigated, and it is discovered that the difference between the two consecutive iteration results of the AMIL algorithm will approximately point to the convergence solution when the precoding and decoding matrices obtained from the intermediate iterations are sufficiently close to their convergence values. Based on this important property, the proposed DQO algorithm employs the line search procedure so that it can converge to the destination directly. In addition, the optimal step size can be determined analytically by optimizing a quartic function. Numerical results show that the proposed DQO algorithm can suppress the interference leakage more rapidly than the traditional AMIL algorithm, and can achieve the same level of sum rate as that of AMIL algorithm with far less iterations and execution time. PMID:26230697

  6. Constructive interference in the spectrum of bremsstrahlung on two amorphous targets

    NASA Astrophysics Data System (ADS)

    Bondarenco, M. V.; Shul'ga, N. F.

    2014-12-01

    We investigate the interference pattern in the spectrum of nondipole bremsstrahlung on two amorphous foils. It contains a suppression at lowest photon energies, an enhancement in the neighboring region, and subsequent evanescent oscillations. The net effect of suppressions and enhancements proves to be zero. The location and the origin of the spectral features is explained. Predictions of the rigorous Molière averaging are compared with those of the Gaussian averaging with Coulomb contributions to the rms multiple scattering angle. Comparison with experimental data and with previous theoretical predictions is included.

  7. Suppression of splenic lymphocyte proliferation by Eucommia ulmoides and genipin.

    PubMed

    Yang, Gabsik; Kyoung Seo, Eun; Lee, Je-Hyun; Young Lee, Joo

    2015-04-01

    We investigated the modulation of innate and adaptive immune cell activation by Eucommia ulmoides Oliver extract (EUE) and its ingredient genipin. As an innate immunity indicator, the phagocytic activity of macrophages was determined by measuring engulfed, fluorescently labeled Escherichia coli. As a surrogate marker for the respective activation of cellular and humoral adaptive immunity, concanavalin A (Con A) and lipopolysaccharide (LPS) induction of primary splenocyte proliferation was assayed in in vitro and ex vivo systems. EUE and genipin suppressed the proliferation of primary splenic lymphocytes induced by Con A or LPS, but not macrophage phagocytosis. Oral administration of EUE and genipin to mice decreased splenic lymphocyte proliferation induced by Con A or LPS. These results revealed that E. ulmoides and genipin suppressed cellular and humoral adaptive immunity, and they suggest that E. ulmoides and genipin are promising candidates for immunosuppressive drugs that target diseases that involve excessive activation of adaptive immunity. PMID:25879499

  8. Resonance--Continuum Interference in Light Higgs Boson Production at a Photon Collider

    SciTech Connect

    Dixon, Lance J.; Sofianatos, Yorgos; /SLAC /Stanford U., Phys. Dept.

    2009-01-06

    We study the effect of interference between the Standard Model Higgs boson resonance and the continuum background in the process {gamma}{gamma} {yields} H {yields} b{bar b} at a photon collider. Taking into account virtual gluon exchange between the final-state quarks, we calculate the leading corrections to the height of the resonance for the case of a light (m{sub H} < 160 GeV) Higgs boson. We find that the interference is destructive and around 0.1-0.2% of the peak height, depending on the mass of the Higgs and the scattering angle. This suppression is smaller by an order of magnitude than the anticipated experimental accuracy at a photon collider. However, the fractional suppression can be significantly larger if the Higgs coupling to b quarks is increased by physics beyond the Standard Model.

  9. The Contextual Interference Effect in Applied Settings

    ERIC Educational Resources Information Center

    Barreiros, Joao; Figueiredo, Teresa; Godinho, Mario

    2007-01-01

    This paper analyses the research literature that approaches the contextual interference effect in applied settings. In contrast to the laboratory settings, in which high interference conditions depress acquisition and promote learning evaluated in retention and transfer tests, in applied settings most of the studies (60%) fail to observe positive…

  10. Assessment and control of spacecraft electromagnetic interference

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Design criteria are presented to provide guidance in assessing electromagnetic interference from onboard sources and establishing requisite control in spacecraft design, development, and testing. A comprehensive state-of-the-art review is given which covers flight experience, sources and transmission of electromagnetic interference, susceptible equipment, design procedure, control techniques, and test methods.

  11. The Nature and Diagnosis of Interference Phenomena.

    ERIC Educational Resources Information Center

    Denison, Norman

    1966-01-01

    The recognition of the systematic nature of the interference of the mother tongue when learning a second language is among the most significant advances in linguistics for the teaching and learning of foreign languages. The work of Weinreich showed that interference between language systems--the absorption of loan words, calques, and phonological,…

  12. Interference and the Law of Energy Conservation

    ERIC Educational Resources Information Center

    Drosd, Robert; Minkin, Leonid; Shapovalov, Alexander S.

    2014-01-01

    Introductory physics textbooks consider interference to be a process of redistribution of energy from the wave sources in the surrounding space resulting in constructive and destructive interferences. As one can expect, the total energy flux is conserved. However, one case of apparent non-conservation energy attracts great attention. Imagine that…

  13. Photoimmune suppression and photocarcinogenesis.

    PubMed

    Ullrich, Stephen E

    2002-03-01

    The primary cause of non-melanoma skin cancer, the most prevalent form of human neoplasia, is the ultraviolet (UV) radiation found in sunlight. Exposing mice to UV radiation induces skin cancers that are highly antigenic. Upon transfer of an UV-induced skin cancer to a normal syngeneic mouse, the tumor cells are recognized and rapidly destroyed by the immune system of the recipient. This raises the question of how these cancers avoided immune destruction during their development in the UV-irradiated host. This question was answered when it was discovered that in addition to being carcinogenic, UV radiation was also immunosuppressive. Studies with immune suppressed transplantation recipients, and biopsy proven skin cancer patients have confirmed that UV-induced immune suppression is a risk factor for skin cancer development in humans. It is of great importance, therefore, to understand the mechanisms underlying UV-induced immune suppression. The focus of this manuscript will be to use some examples from the more recent scientific literature to review the mechanisms by which UV radiation suppresses the immune response and allows for the progressive outgrowth of antigenic skin tumors. PMID:11861222

  14. Parasitic suppressing circuit

    NASA Technical Reports Server (NTRS)

    Fowler, J. T.; Raposa, F. L. (Inventor)

    1973-01-01

    A circuit for suppressing parasitic oscillations across an inductor operating in a resonant mode is described. The circuit includes a switch means and resistive means connected serially across the inductor. A unidirectional resistive-capacitive network is also connected across the inductor and to the switch means to automatically render the switch means conducting when inductive current through the inductor ceases to flow.

  15. Frequency Adaptability and Waveform Design for OFDM Radar Space-Time Adaptive Processing

    SciTech Connect

    Sen, Satyabrata; Glover, Charles Wayne

    2012-01-01

    We propose an adaptive waveform design technique for an orthogonal frequency division multiplexing (OFDM) radar signal employing a space-time adaptive processing (STAP) technique. We observe that there are inherent variabilities of the target and interference responses in the frequency domain. Therefore, the use of an OFDM signal can not only increase the frequency diversity of our system, but also improve the target detectability by adaptively modifying the OFDM coefficients in order to exploit the frequency-variabilities of the scenario. First, we formulate a realistic OFDM-STAP measurement model considering the sparse nature of the target and interference spectra in the spatio-temporal domain. Then, we show that the optimal STAP-filter weight-vector is equal to the generalized eigenvector corresponding to the minimum generalized eigenvalue of the interference and target covariance matrices. With numerical examples we demonstrate that the resultant OFDM-STAP filter-weights are adaptable to the frequency-variabilities of the target and interference responses, in addition to the spatio-temporal variabilities. Hence, by better utilizing the frequency variabilities, we propose an adaptive OFDM-waveform design technique, and consequently gain a significant amount of STAP-performance improvement.

  16. Phonon-Mediated Nonclassical Interference in Diamond

    NASA Astrophysics Data System (ADS)

    England, Duncan G.; Fisher, Kent A. G.; MacLean, Jean-Philippe W.; Bustard, Philip J.; Heshami, Khabat; Resch, Kevin J.; Sussman, Benjamin J.

    2016-08-01

    Quantum interference of single photons is a fundamental aspect of many photonic quantum processing and communication protocols. Interference requires that the multiple pathways through an interferometer be temporally indistinguishable to within the coherence time of the photon. In this Letter, we use a diamond quantum memory to demonstrate interference between quantum pathways, initially temporally separated by many multiples of the optical coherence time. The quantum memory can be viewed as a light-matter beam splitter, mapping a THz-bandwidth single photon to a variable superposition of the output optical mode and stored phononic mode. Because the memory acts both as a beam splitter and as a buffer, the relevant coherence time for interference is not that of the photon, but rather that of the memory. We use this mechanism to demonstrate nonclassical single-photon and two-photon interference between quantum pathways initially separated by several picoseconds, even though the duration of the photons themselves is just ˜250 fs .

  17. Interference control in children with reading difficulties.

    PubMed

    Wang, Shinmin; Gathercole, Susan E

    2015-01-01

    Two studies investigated whether the greater Stroop interference reported in children with reading difficulties compared to typical readers of the same age represents a generalized deficit in interference control or a consequence of their reading problems. In Study 1, a color-word Stroop task and a nonverbal task involving responses to locations associated with pictures were administered to 23 children with single word reading difficulties and 22 typically developing children matched for age and nonverbal ability. Children with reading difficulties showed disproportionate interference effects in the color-word Stroop but not the nonverbal task. In Study 2, groups of poor and typical readers completed a spatial Stroop task with printed input that did not require a verbal response and a nonverbal analogue. Both groups showed comparable interference in these two tasks. Thus, the reported problems in the color-word Stroop task in children with reading difficulties do not appear to entail general impairments in interference control. PMID:24852235

  18. Improved CDMA Performance Using Parallel Interference Cancellation

    NASA Technical Reports Server (NTRS)

    Simon, Marvin; Divsalar, Dariush

    1995-01-01

    This report considers a general parallel interference cancellation scheme that significantly reduces the degradation effect of user interference but with a lesser implementation complexity than the maximum-likelihood technique. The scheme operates on the fact that parallel processing simultaneously removes from each user the interference produced by the remaining users accessing the channel in an amount proportional to their reliability. The parallel processing can be done in multiple stages. The proposed scheme uses tentative decision devices with different optimum thresholds at the multiple stages to produce the most reliably received data for generation and cancellation of user interference. The 1-stage interference cancellation is analyzed for three types of tentative decision devices, namely, hard, null zone, and soft decision, and two types of user power distribution, namely, equal and unequal powers. Simulation results are given for a multitude of different situations, in particular, those cases for which the analysis is too complex.

  19. Noise suppression methods for robust speech processing

    NASA Astrophysics Data System (ADS)

    Boll, S. F.; Kajiya, J.; Youngberg, J.; Petersen, T. L.; Ravindra, H.; Done, W.; Cox, B. V.; Cohen, E.

    1981-04-01

    Robust speech processing in practical operating environments requires effective environmental and processor noise suppression. This report describes the technical findings and accomplishments during the reporting period for the research program funded to develop real-time, compressed speech analysis-synthesis algorithms whose performance is invariant under signal contamination. Fulfillment of this requirement is necessary to insure reliable secure compressed speech transmission within realistic military command and control environments. Overall contributions resulting from this research program include the understanding of how environmental noise degrades narrow band, coded speech, development of appropriate real-time noise suppression algorithms, and development of speech parameter identification methods that consider signal contamination as a fundamental element in the estimation process. This report describes the research and results in the areas of noise suppression using the dual input adaptive noise cancellation articulation rate change techniques, spectral subtraction and a description of an experiment which demonstrated that the spectral substraction noise suppression algorithm can improve the intelligibility of 2400 bps, LPC-10 coded, helicopter speech by 10.6 points. In addition summaries are included of prior studies in Constant-Q signal analysis and synthesis, perceptual modelling, speech activity detection, and pole-zero modelling of noisy signals. Three recent studies in speech modelling using the critical band analysis-synthesis transform and using splines are then presented. Finally a list of major publications generated under this contract is given.

  20. Fano interference governs wave transport in disordered systems

    PubMed Central

    Poddubny, Alexander N.; Rybin, Mikhail V.; Limonov, Mikhail F.; Kivshar, Yuri S.

    2012-01-01

    Light localization in disordered systems and Bragg scattering in regular periodic structures are considered traditionally as two entirely opposite phenomena: disorder leads to degradation of coherent Bragg scattering whereas Anderson localization is suppressed by periodicity. Here we reveal a non-trivial link between these two phenomena, through the Fano interference between Bragg scattering and disorder-induced scattering, that triggers both localization and de-localization in random systems. We find unexpected transmission enhancement and spectrum inversion when the Bragg stop-bands are transformed into the Bragg pass-bands solely owing to disorder. Fano resonances are always associated with coherent scattering in regular systems, but our discovery of disorder-induced Fano resonances may provide novel insights into many features of the transport phenomena of photons, phonons, and electrons. Owning to ergodicity, the Fano resonance is a fingerprint feature for any realization of the structure with a certain degree of disorder. PMID:22735442

  1. Quantum interference in a driven two-level atom

    NASA Astrophysics Data System (ADS)

    Ficek, Z.; Rudolph, T.

    1999-12-01

    We show that a dynamical suppression of spontaneous emission, predicted for a three-level atom [S.-Y. Zhu and M. O. Scully, Phys. Rev. Lett. 76, 388 (1996)] can occur in a two-level atom driven by a polychromatic field. We find that the quantum interference, responsible for the cancellation of spontaneous emission, appears between different channels of transitions among the dressed states of the driven atom. We discuss the effect for bichromatic and trichromatic (amplitude-modulated) fields and find that these two cases lead to the cancellation of spontaneous emission in different parts of the fluorescence spectrum. Our system has the advantage of being easily accessible by current experiments.

  2. RNA Interference Prevents Autosomal-Dominant Hearing Loss.

    PubMed

    Shibata, Seiji B; Ranum, Paul T; Moteki, Hideaki; Pan, Bifeng; Goodwin, Alexander T; Goodman, Shawn S; Abbas, Paul J; Holt, Jeffrey R; Smith, Richard J H

    2016-06-01

    Hearing impairment is the most common sensory deficit. It is frequently caused by the expression of an allele carrying a single dominant missense mutation. Herein, we show that a single intracochlear injection of an artificial microRNA carried in a viral vector can slow progression of hearing loss for up to 35 weeks in the Beethoven mouse, a murine model of non-syndromic human deafness caused by a dominant gain-of-function mutation in Tmc1 (transmembrane channel-like 1). This outcome is noteworthy because it demonstrates the feasibility of RNA-interference-mediated suppression of an endogenous deafness-causing allele to slow progression of hearing loss. Given that most autosomal-dominant non-syndromic hearing loss in humans is caused by this mechanism of action, microRNA-based therapeutics might be broadly applicable as a therapy for this type of deafness. PMID:27236922

  3. A fast, robust algorithm for power line interference cancellation in neural recording

    NASA Astrophysics Data System (ADS)

    Keshtkaran, Mohammad Reza; Yang, Zhi

    2014-04-01

    Objective. Power line interference may severely corrupt neural recordings at 50/60 Hz and harmonic frequencies. The interference is usually non-stationary and can vary in frequency, amplitude and phase. To retrieve the gamma-band oscillations at the contaminated frequencies, it is desired to remove the interference without compromising the actual neural signals at the interference frequency bands. In this paper, we present a robust and computationally efficient algorithm for removing power line interference from neural recordings. Approach. The algorithm includes four steps. First, an adaptive notch filter is used to estimate the fundamental frequency of the interference. Subsequently, based on the estimated frequency, harmonics are generated by using discrete-time oscillators, and then the amplitude and phase of each harmonic are estimated by using a modified recursive least squares algorithm. Finally, the estimated interference is subtracted from the recorded data. Main results. The algorithm does not require any reference signal, and can track the frequency, phase and amplitude of each harmonic. When benchmarked with other popular approaches, our algorithm performs better in terms of noise immunity, convergence speed and output signal-to-noise ratio (SNR). While minimally affecting the signal bands of interest, the algorithm consistently yields fast convergence (<100 ms) and substantial interference rejection (output SNR >30 dB) in different conditions of interference strengths (input SNR from -30 to 30 dB), power line frequencies (45-65 Hz) and phase and amplitude drifts. In addition, the algorithm features a straightforward parameter adjustment since the parameters are independent of the input SNR, input signal power and the sampling rate. A hardware prototype was fabricated in a 65 nm CMOS process and tested. Software implementation of the algorithm has been made available for open access at https://github.com/mrezak/removePLI. Significance. The proposed

  4. Application of isothermal titration calorimeter for screening bitterness-suppressing molecules of quinine.

    PubMed

    Zhang, Yifan; Zhu, Youwei; Zhao, Na; Wu, Jinhui; Hu, Yiqiao

    2016-01-01

    Bitterness-suppressing molecules have drawn ever-increasing attention these years for some unique advantages like low molecular weight, tastelessness and no interference on drug bioavailability. L-Arg was reported to suppress the bitterness of quinine, and we happened to find that the suppressing effects could be demonstrated by isothermal titration calorimeter (ITC). In this study, we investigated the possibility of using ITC to screen bitterness-suppressing molecules for quinine. Among the amino acids we screened, L-Lys bond quinine with high affinity. The results of ITC correlated well with the results of human sensory experiments. L-Arg and L-Lys could suppress the bitterness of quinine while other amino acids could not. Therefore, ITC has the potential to screen bitterness-suppressing molecules. PMID:26213068

  5. Cognitive Load Undermines Thought Suppression in Acute Stress Disorder.

    PubMed

    Nixon, Reginald D V; Rackebrandt, Julie

    2016-05-01

    Thought suppression studies demonstrate that attempts to suppress can be undermined by cognitive load. We report the first instance in which this has been tested experimentally in a sample of recently traumatized individuals. Individuals with and without acute stress disorder (ASD) were recruited following recent trauma and randomized to load or no load conditions (N=56). They monitored intrusive memories during baseline, suppression, and think anything phases. The impact of suppression and load on self-reported intrusions, attention bias (dot-probe), and memory priming (word-stem task) was assessed. The ASD load group were less able to suppress memories (d=0.32, CI95 [-0.15, 0.83], p=.088) than the ASD no load group (d=0.63, CI95 [0.08, 1.24], p<.001). In the think anything phase, the ASD load group reported more intrusions than the ASD no load or non-ASD groups (with and without load). No consistent findings were observed in relation to attentional bias. ASD load individuals exhibited stronger priming responses for motor vehicle accident and assault words than all other groups (ds between 0.35-0.73). Working memory did not moderate any outcomes of interest. The findings indicate that cognitive load interferes with suppression and may enhance access to trauma memories and associated material. The study extends previous research by demonstrating these effects for the first time in a clinical sample of recent survivors of trauma. PMID:27157032

  6. Rote of adaptation exercises in clinical practice.

    PubMed

    Kirtane, M V

    1999-04-01

    Adaptation, habitution and compensation are the mechanisms involved in rehabilitation of vertigo patients. In Vestibular Rehabilitation Therapy (VRT), patients are advised to perform a series of maneuvers involving head, eye and body movements which stimulate the in-built adaptive mechanisms. Cawthorne and Cooksey were the first to describe adaptation exercises, which are further modified. Norre has designed VRT test battery of specific exercises. Drug treatment used along with VRT should not interfere with the compensation mechanism. Anti-vertigo drug Betahistine has been shown to hasten the compensation and hence is suitable for use with VRT. PMID:23119512

  7. Assessment of interference in biosorption of a heavy metal.

    PubMed

    Figueira, M M; Volesky, B; Ciminelli, V S

    1997-05-20

    Nonliving biomass of Sargassum, a brown marine alga, is capable of binding more than 10% of its dry weight in toxic cadmium ions. Although ubiquitous iron interferes with Cd uptake, only approximately 4.5% of it is sequestered (biomass dry weight). Biosorption of both metals at ph 4.5 could be described by Langmuir-type isotherms with b, the affinity-related coefficient (Cd: b = 0.015; Fe: b = 0.027). The interference of Fe with Cd uptake, and vice versa, was assessed by deriving three-dimensional equilibrium two-metal sorption isotherm surfaces, smoothed and "cut" to reveal the inhibition effect of Fe on biosorption of Cd: at the equilibrium concentration Cf[Cd] = 1.5 mM, the presence of Fe at 1.5 mM equilibrium concentration suppressed the Cd uptake to only 76% of the original value. For 50% Cd uptake reduction, a very high equilibrium Fe presence of 4.5 mM was required. The Cd presence affected the uptake of Fe very strongly. To obtain equal values of uptake for each metal in the biosorbent, the ratio of equilibrium concentrations of 0.42 Cd to 1 Fe is necessary in the liquid phase. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 344-350, 1997. PMID:18634101

  8. Suppressive mechanisms in visual motion processing: From perception to intelligence.

    PubMed

    Tadin, Duje

    2015-10-01

    Perception operates on an immense amount of incoming information that greatly exceeds the brain's processing capacity. Because of this fundamental limitation, the ability to suppress irrelevant information is a key determinant of perceptual efficiency. Here, I will review a series of studies investigating suppressive mechanisms in visual motion processing, namely perceptual suppression of large, background-like motions. These spatial suppression mechanisms are adaptive, operating only when sensory inputs are sufficiently robust to guarantee visibility. Converging correlational and causal evidence links these behavioral results with inhibitory center-surround mechanisms, namely those in cortical area MT. Spatial suppression is abnormally weak in several special populations, including the elderly and individuals with schizophrenia-a deficit that is evidenced by better-than-normal direction discriminations of large moving stimuli. Theoretical work shows that this abnormal weakening of spatial suppression should result in motion segregation deficits, but direct behavioral support of this hypothesis is lacking. Finally, I will argue that the ability to suppress information is a fundamental neural process that applies not only to perception but also to cognition in general. Supporting this argument, I will discuss recent research that shows individual differences in spatial suppression of motion signals strongly predict individual variations in IQ scores. PMID:26299386

  9. Applying contextual interference to the Pawlata roll.

    PubMed

    Smith, P J; Davies, M

    1995-12-01

    Contextual interference is manipulated by changing the practice order of a number of similar motor tasks, so that the learning context of each interferes with that of the other. The effect has been found to generalize to baseball batting, badminton serving and volleyball skills. The present study examined whether this practice technique could be applied to a Pawlata roll in a kayak. The study was further motivated by the fact that many instructors in Britain currently advocate learning the Pawlata roll in one direction only to a criterion of accuracy, thereafter transferring to the opposite direction. Contextual interference literature predicts that skill retention would be better served by practising on alternate sides. Accordingly, 16 undergraduate students with no kayaking experience were randomly allocated to either a low contextual interference group, which followed U'ren's (1993) recommendations, or a high contextual interference group, which practised the skill on alternate sides. The high contextual interference group took less time to acquire the skill, and were also quicker to achieve successful performance in retention (full roll) and transfer (half roll) tests, regardless of the direction of the roll, 1 week later. The time savings in practice were not expected, as acquisition under high contextual interference was improved rather than impaired. This finding suggests that bilateral transfer was increased by randomizing practice. These results are worthy of further investigation, in that they suggest that the recommended training methods may not be optimal. PMID:8850571

  10. Mechanisms and ecological consequences of plant defence induction and suppression in herbivore communities

    PubMed Central

    Kant, M. R.; Jonckheere, W.; Knegt, B.; Lemos, F.; Liu, J.; Schimmel, B. C. J.; Villarroel, C. A.; Ataide, L. M. S.; Dermauw, W.; Glas, J. J.; Egas, M.; Janssen, A.; Van Leeuwen, T.; Schuurink, R. C.; Sabelis, M. W.; Alba, J. M.

    2015-01-01

    give rise to exploitative competition and facilitation within ecological communities “inhabiting” a plant. Conclusions Herbivores have evolved diverse strategies, which are not mutually exclusive, to decrease the negative effects of plant defences in order to maximize the conversion of plant material into offspring. Numerous adaptations have been found in herbivores, enabling them to dismantle or bypass defensive barriers, to avoid tissues with relatively high levels of defensive chemicals or to metabolize these chemicals once ingested. In addition, some herbivores interfere with the onset or completion of induced plant defences, resulting in the plant’s resistance being partly or fully suppressed. The ability to suppress induced plant defences appears to occur across plant parasites from different kingdoms, including herbivorous arthropods, and there is remarkable diversity in suppression mechanisms. Suppression may strongly affect the structure of the food web, because the ability to suppress the activation of defences of a communal host may facilitate competitors, whereas the ability of a herbivore to cope with activated plant defences will not. Further characterization of the mechanisms and traits that give rise to suppression of plant defences will enable us to determine their role in shaping direct and indirect interactions in food webs and the extent to which these determine the coexistence and persistence of species. PMID:26019168

  11. A modification of the successive projections algorithm for spectral variable selection in the presence of unknown interferents.

    PubMed

    Soares, Sófacles Figueredo Carreiro; Galvão, Roberto Kawakami Harrop; Araújo, Mário César Ugulino; da Silva, Edvan Cirino; Pereira, Claudete Fernandes; de Andrade, Stéfani Iury Evangelista; Leite, Flaviano Carvalho

    2011-03-01

    This work proposes a modification to the successive projections algorithm (SPA) aimed at selecting spectral variables for multiple linear regression (MLR) in the presence of unknown interferents not included in the calibration data set. The modified algorithm favours the selection of variables in which the effect of the interferent is less pronounced. The proposed procedure can be regarded as an adaptive modelling technique, because the spectral features of the samples to be analyzed are considered in the variable selection process. The advantages of this new approach are demonstrated in two analytical problems, namely (1) ultraviolet-visible spectrometric determination of tartrazine, allure red and sunset yellow in aqueous solutions under the interference of erythrosine, and (2) near-infrared spectrometric determination of ethanol in gasoline under the interference of toluene. In these case studies, the performance of conventional MLR-SPA models is substantially degraded by the presence of the interferent. This problem is circumvented by applying the proposed Adaptive MLR-SPA approach, which results in prediction errors smaller than those obtained by three other multivariate calibration techniques, namely stepwise regression, full-spectrum partial-least-squares (PLS) and PLS with variables selected by a genetic algorithm. An inspection of the variable selection results reveals that the Adaptive approach successfully avoids spectral regions in which the interference is more intense. PMID:21338751

  12. Pressure suppression containment system

    DOEpatents

    Gluntz, Douglas M.; Townsend, Harold E.

    1994-03-15

    A pressure suppression containment system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and a gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel. The wetwell pool includes a plenum for receiving the non-condensable gas carried with steam from the drywell following a loss-of coolant-accident (LOCA). The wetwell plenum is vented to a plenum above the GDCS pool following the LOCA for suppressing pressure rise within the containment vessel. A method of operation includes channeling steam released into the drywell following the LOCA into the wetwell pool for cooling along with the non-condensable gas carried therewith. The GDCS pool is then drained by gravity, and the wetwell plenum is vented into the GDCS plenum for channeling the non-condensable gas thereto.

  13. Pressure suppression containment system

    DOEpatents

    Gluntz, D.M.; Townsend, H.E.

    1994-03-15

    A pressure suppression containment system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and a gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel. The wetwell pool includes a plenum for receiving the non-condensable gas carried with steam from the drywell following a loss-of-coolant-accident (LOCA). The wetwell plenum is vented to a plenum above the GDCS pool following the LOCA for suppressing pressure rise within the containment vessel. A method of operation includes channeling steam released into the drywell following the LOCA into the wetwell pool for cooling along with the non-condensable gas carried therewith. The GDCS pool is then drained by gravity, and the wetwell plenum is vented into the GDCS plenum for channeling the non-condensable gas thereto. 6 figures.

  14. Adaptive noise estimation and suppression for improving microseismic event detection

    NASA Astrophysics Data System (ADS)

    Mousavi, S. Mostafa; Langston, Charles A.

    2016-09-01

    Microseismic data recorded by surface arrays are often strongly contaminated by unwanted noise. This background noise makes the detection of small magnitude events difficult. A noise level estimation and noise reduction algorithm is presented for microseismic data analysis based upon minimally controlled recursive averaging and neighborhood shrinkage estimators. The method might not be compared with more sophisticated and computationally expensive denoising algorithm in terms of preserving detailed features of seismic signal. However, it is fast and data-driven and can be applied in real-time processing of continuous data for event detection purposes. Results from application of this algorithm to synthetic and real seismic data show that it holds a great promise for improving microseismic event detection.

  15. Gut physiology mediates a trade-off between adaptation to malnutrition and susceptibility to food-borne pathogens.

    PubMed

    Vijendravarma, Roshan K; Narasimha, Sunitha; Chakrabarti, Sveta; Babin, Aurelie; Kolly, Sylvain; Lemaitre, Bruno; Kawecki, Tadeusz J

    2015-10-01

    The animal gut plays a central role in tackling two common ecological challenges, nutrient shortage and food-borne parasites, the former by efficient digestion and nutrient absorption, the latter by acting as an immune organ and a barrier. It remains unknown whether these functions can be independently optimised by evolution, or whether they interfere with each other. We report that Drosophila melanogaster populations adapted during 160 generations of experimental evolution to chronic larval malnutrition became more susceptible to intestinal infection with the opportunistic bacterial pathogen Pseudomonas entomophila. However, they do not show suppressed immune response or higher bacterial loads. Rather, their increased susceptibility to P. entomophila is largely mediated by an elevated predisposition to loss of intestinal barrier integrity upon infection. These results may reflect a trade-off between the efficiency of nutrient extraction from poor food and the protective function of the gut, in particular its tolerance to pathogen-induced damage. PMID:26249109

  16. Adaptive detection method of infrared small target based on target-background separation via robust principal component analysis

    NASA Astrophysics Data System (ADS)

    Wang, Chuanyun; Qin, Shiyin

    2015-03-01

    Motivated by the robust principal component analysis, infrared small target image is regarded as low-rank background matrix corrupted by sparse target and noise matrices, thus a new target-background separation model is designed, subsequently, an adaptive detection method of infrared small target is presented. Firstly, multi-scale transform and patch transform are used to generate an image patch set for infrared small target detection; secondly, target-background separation of each patch is achieved by recovering the low-rank and sparse matrices using adaptive weighting parameter; thirdly, the image reconstruction and fusion are carried out to obtain the entire separated background and target images; finally, the infrared small target detection is realized by threshold segmentation of template matching similarity measurement. In order to validate the performance of the proposed method, three experiments: target-background separation, background clutter suppression and infrared small target detection, are performed over different clutter background with real infrared small targets in single-frame or sequence images. A series of experiment results demonstrate that the proposed method can not only suppress background clutter effectively even if with strong noise interference but also detect targets accurately with low false alarm rate.

  17. Wave and Particle in Molecular Interference Lithography

    SciTech Connect

    Juffmann, Thomas; Truppe, Stefan; Geyer, Philipp; Major, Andras G.; Arndt, Markus; Deachapunya, Sarayut; Ulbricht, Hendrik

    2009-12-31

    The wave-particle duality of massive objects is a cornerstone of quantum physics and a key property of many modern tools such as electron microscopy, neutron diffraction or atom interferometry. Here we report on the first experimental demonstration of quantum interference lithography with complex molecules. Molecular matter-wave interference patterns are deposited onto a reconstructed Si(111) 7x7 surface and imaged using scanning tunneling microscopy. Thereby both the particle and the quantum wave character of the molecules can be visualized in one and the same image. This new approach to nanolithography therefore also represents a sensitive new detection scheme for quantum interference experiments.

  18. Wave and particle in molecular interference lithography.

    PubMed

    Juffmann, Thomas; Truppe, Stefan; Geyer, Philipp; Major, András G; Deachapunya, Sarayut; Ulbricht, Hendrik; Arndt, Markus

    2009-12-31

    The wave-particle duality of massive objects is a cornerstone of quantum physics and a key property of many modern tools such as electron microscopy, neutron diffraction or atom interferometry. Here we report on the first experimental demonstration of quantum interference lithography with complex molecules. Molecular matter-wave interference patterns are deposited onto a reconstructed Si(111) 7x7 surface and imaged using scanning tunneling microscopy. Thereby both the particle and the quantum wave character of the molecules can be visualized in one and the same image. This new approach to nanolithography therefore also represents a sensitive new detection scheme for quantum interference experiments. PMID:20366311

  19. Gas Interference in Sucker Rod Pump

    NASA Astrophysics Data System (ADS)

    Samad, Abdus

    2010-10-01

    Commonly used artificial lift or dewatering system is sucker rod pump and gas interference of the pump is the biggest issue in the oil and gas industry. Gas lock or fluid pound problems occur due to the gas interference when the pump has partially or completely unfilled plunger barrel. There are several techniques available in the form of patents to solve these problems but those techniques have positive as well as negative aspects. Some of the designs rely on the leakage and some of the designs rely on the mechanical arrangements etc to break the gas lock. The present article compares the existing gas interference handling techniques.

  20. Menstrual suppression: current perspectives

    PubMed Central

    Hillard, Paula Adams

    2014-01-01

    Menstrual suppression to provide relief of menstrual-related symptoms or to manage medical conditions associated with menstrual morbidity or menstrual exacerbation has been used clinically since the development of steroid hormonal therapies. Options range from the extended or continuous use of combined hormonal oral contraceptives, to the use of combined hormonal patches and rings, progestins given in a variety of formulations from intramuscular injection to oral therapies to intrauterine devices, and other agents such as gonadotropin-releasing hormone (GnRH) antagonists. The agents used for menstrual suppression have variable rates of success in inducing amenorrhea, but typically have increasing rates of amenorrhea over time. Therapy may be limited by side effects, most commonly irregular, unscheduled bleeding. These therapies can benefit women’s quality of life, and by stabilizing the hormonal milieu, potentially improve the course of underlying medical conditions such as diabetes or a seizure disorder. This review addresses situations in which menstrual suppression may be of benefit, and lists options which have been successful in inducing medical amenorrhea. PMID:25018654

  1. Vibrotactile suppression of tinnitus

    NASA Astrophysics Data System (ADS)

    Lenhardt, Martin L.

    2002-05-01

    At the Society's 142nd meeting, the efficacy of high frequency bone conducted stimulation in suppressing tinnitus was presented. The hypothesized mechanism was the reprogramming of frequency tuning of auditory neurons in the central nervous system, secondarily to peripheral hearing loss. This mechanism is unlikely in cases of tinnitus in the presence of normal audiometric sensitivity. There is the possibility that hearing loss above 10 kHz can play a role in tinnitus, an association not thoroughly explored. Somatomotor stimulation influencing the quality of tinnitus has been reported, as have interconnections of the auditory and somatosensory systems. There would appear to be an evolutionary advantage of linking the sensorimotor organization of the external ear and the auditory function of the brainstem in sound localization. Thus, stimulation of the pinna and post auricular area may be a means of suppressing tinnitus. To that end a thin aluminum ceramic bimorph was constructed to fit on the inner surface of the pinna. When driven by low (<100 Hz) and high (>10 kHz) frequencies multiplied by MHz carriers, demodulation in the skin resulted in vibrotactile stimulation. Tactile stimulation was an adjunct to the high frequencies resulting in a multimodal suppressive effect in a small pilot study.

  2. COMPARISON OF RADIO-FREQUENCY INTERFERENCE MITIGATION STRATEGIES FOR DISPERSED PULSE DETECTION

    SciTech Connect

    Hogden, John; Vander Wiel, Scott; Michalak, Sarah; Bower, Geoffrey C.; Siemion, Andrew; Werthimer, Daniel

    2012-03-10

    Impulsive radio-frequency signals from astronomical sources are dispersed by the frequency-dependent index of refraction of the interstellar media and so appear as chirped signals when they reach Earth. Searches for dispersed impulses have been limited by false detections due to radio-frequency interference (RFI) and, in some cases, artifacts of the instrumentation. Many authors have discussed techniques to excise or mitigate RFI in searches for fast transients, but comparisons between different approaches are lacking. This work develops RFI mitigation techniques for use in searches for dispersed pulses, employing data recorded in a 'Fly's Eye' mode of the Allen Telescope Array as a test case. We gauge the performance of several RFI mitigation techniques by adding dispersed signals to data containing RFI and comparing false alarm rates at the observed signal-to-noise ratios of the added signals. We find that Huber filtering is most effective at removing broadband interferers, while frequency centering is most effective at removing narrow frequency interferers. Neither of these methods is effective over a broad range of interferers. A method that combines Huber filtering and adaptive interference cancelation provides the lowest number of false positives over the interferers considered here. The methods developed here have application to other searches for dispersed pulses in incoherent spectra, especially those involving multiple beam systems.

  3. Comparison of Radio-frequency Interference Mitigation Strategies for Dispersed Pulse Detection

    NASA Astrophysics Data System (ADS)

    Hogden, John; Vander Wiel, Scott; Bower, Geoffrey C.; Michalak, Sarah; Siemion, Andrew; Werthimer, Daniel

    2012-03-01

    Impulsive radio-frequency signals from astronomical sources are dispersed by the frequency-dependent index of refraction of the interstellar media and so appear as chirped signals when they reach Earth. Searches for dispersed impulses have been limited by false detections due to radio-frequency interference (RFI) and, in some cases, artifacts of the instrumentation. Many authors have discussed techniques to excise or mitigate RFI in searches for fast transients, but comparisons between different approaches are lacking. This work develops RFI mitigation techniques for use in searches for dispersed pulses, employing data recorded in a "Fly's Eye" mode of the Allen Telescope Array as a test case. We gauge the performance of several RFI mitigation techniques by adding dispersed signals to data containing RFI and comparing false alarm rates at the observed signal-to-noise ratios of the added signals. We find that Huber filtering is most effective at removing broadband interferers, while frequency centering is most effective at removing narrow frequency interferers. Neither of these methods is effective over a broad range of interferers. A method that combines Huber filtering and adaptive interference cancelation provides the lowest number of false positives over the interferers considered here. The methods developed here have application to other searches for dispersed pulses in incoherent spectra, especially those involving multiple beam systems.

  4. Two-color interference effect involving three-photon atomic excitation and four-wave mixing in crossed laser beams

    SciTech Connect

    Peet, V.

    2007-09-15

    Through multiphoton ionization measurements, the polarization effects in destructive quantum interference under three-photon resonant excitation have been studied. Recent observations [V. Peet, Phys. Rev. A 74, 033406 (2006)] have indicated that contrary to the well-known pattern of a total suppression of resonance excitation, the destructive interference becomes incomplete if three-photon transition is driven by crossed beams with orthogonal polarization planes. These observations have been tested for a more general case of two-color excitation and very similar polarization-dependent anomalies in the interference character have been registered. It has been shown that the destructive interference is modified and the resonance excitation does occur if two crossed laser beams have opposite circular polarizations. The pressure-induced evolution of the uncanceled ionization peaks has the ratio of blue shift to width close to 0.5 exactly as it is known for resonance ionization peaks registered under excitation by counterpropagating laser beams.

  5. Long-Term and Transitory Interference Effects

    ERIC Educational Resources Information Center

    Glazer, Howard I.; Weiss, Jay M.

    1976-01-01

    If animals receive inescapable electric shocks, their subsequent avoidance-escape learning is poor. This phenomenon, which can be called "the interference effect", was studied in four experiments. (Editor)

  6. Two Further Experiments on Electron Interference

    ERIC Educational Resources Information Center

    Matteucci, G.; Pozzi, G.

    1978-01-01

    Presents the results of two experiments concerning the phenomena of the interference of probabilities and of the so called Aharonov-Bohm effect. An electron biprism and a standard electron microscope have been used for the experiments. (Author/GA)

  7. 47 CFR 27.1221 - Interference protection.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Interference protection. 27.1221 Section 27.1221 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband...

  8. 47 CFR 27.1221 - Interference protection.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Interference protection. 27.1221 Section 27.1221 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband...

  9. 47 CFR 27.1221 - Interference protection.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Interference protection. 27.1221 Section 27.1221 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband...

  10. 47 CFR 27.1221 - Interference protection.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Interference protection. 27.1221 Section 27.1221 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband...

  11. 47 CFR 27.1221 - Interference protection.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Interference protection. 27.1221 Section 27.1221 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband...

  12. [FT4 immunoassay interference : A case report].

    PubMed

    Chaabouni, Khansa; Hargafi, Khaoula; Elleuch, Aida; Messedi, Mariem; Turki, Mouna; Lahyani, Amina; Ayedi, Fatma

    2015-04-01

    Measurement of thyrotropin and free thyroxin made using immunoassays are usually needed in clinical endocrinology. Here, we report a case of a patient with type 2 diabetes who presented a weight loss. To eliminate hyperthyroidism, thyroid function tests were performed. Free thyroxin (FT4) was decreased using two automated immunoassays TOSOH AIA 1800 and Roche ELECSYS 2010, with a normal thyrotropin value. Thyroid function tests repeated a month later were normal. The patient's history revealed contact with sheep, which may partly explain the interference. Investigations into the patient's serum were carried out using both the PEG test and dilution test. Interference factors were probably antibodies. Despite progress in immunoassays, we should be aware of interference occurrence since it can lead to false results, unnecessary investigations and incorrect treatment. Thus, simple tests must be carried out as if interference in immunoassays were suspected. Dilutions and PEG tests are generally performed as first line investigations. PMID:26375746

  13. Small Aircraft RF Interference Path Loss Measurements

    NASA Technical Reports Server (NTRS)

    Nguyen, Truong X.; Koppen, Sandra V.; Ely, Jay J.; Szatkowski, George N.; Mielnik, John J.; Salud, Maria Theresa P.

    2007-01-01

    Interference to aircraft radio receivers is an increasing concern as more portable electronic devices are allowed onboard. Interference signals are attenuated as they propagate from inside the cabin to aircraft radio antennas mounted on the outside of the aircraft. The attenuation level is referred to as the interference path loss (IPL) value. Significant published IPL data exists for transport and regional category airplanes. This report fills a void by providing data for small business/corporate and general aviation aircraft. In this effort, IPL measurements are performed on ten small aircraft of different designs and manufacturers. Multiple radio systems are addressed. Along with the typical worst-case coupling values, statistical distributions are also reported that could lead to more meaningful interference risk assessment.

  14. Small Aircraft RF Interference Path Loss

    NASA Technical Reports Server (NTRS)

    Nguyen, Truong X.; Koppen, Sandra V.; Ely, Jay J.; Szatkowski, George N.; Mielnik, John J.; Salud, Maria Theresa P.

    2007-01-01

    Interference to aircraft radio receivers is an increasing concern as more portable electronic devices are allowed onboard. Interference signals are attenuated as they propagate from inside the cabin to aircraft radio antennas mounted on the outside of the aircraft. The attenuation level is referred to as the interference path loss (IPL) value. Significant published IPL data exists for transport and regional category airplanes. This report fills a void by providing data for small business/corporate and general aviation aircraft. In this effort, IPL measurements are performed on ten small aircraft of different designs and manufacturers. Multiple radio systems are addressed. Along with the typical worst-case coupling values, statistical distributions are also reported that could lead to better interference risk assessment.

  15. 47 CFR 74.1203 - Interference.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... service of its primary station or cause such interference within the boundaries of the principal community... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES FM Broadcast Translator Stations...

  16. Parallel interference cancellation for CDMA applications

    NASA Technical Reports Server (NTRS)

    Divsalar, Dariush (Inventor); Simon, Marvin K. (Inventor); Raphaeli, Dan (Inventor)

    1997-01-01

    The present invention provides a method of decoding a spread spectrum composite signal, the composite signal comprising plural user signals that have been spread with plural respective codes, wherein each coded signal is despread, averaged to produce a signal value, analyzed to produce a tentative decision, respread, summed with other respread signals to produce combined interference signals, the method comprising scaling the combined interference signals with a weighting factor to produce a scaled combined interference signal, scaling the composite signal with the weighting factor to produce a scaled composite signal, scaling the signal value by the complement of the weighting factor to produce a leakage signal, combining the scaled composite signal, the scaled combined interference signal and the leakage signal to produce an estimate of a respective user signal.

  17. Interference Analysis Process in Military Aircraft Industry

    NASA Astrophysics Data System (ADS)

    Rothenhaeusler, M.; Poisel, W.

    2012-05-01

    As flying platforms do have limited space for integration and increasing demands for antennas, interference and EMC analysis becomes ever more relevant for optimised antenna concepts. Of course aerodynamic and operational aspects are still important and can not be neglected, but interference can also be a performance killer if it is not analysed in a proper way. This paper describes an interference analysis process which is based on the electrical data of all transmitters and receivers, in- and out-of-band numerical simulation of the decoupling values of all involved antennas and includes EMC relevant data of conducted and radiated emissions, based on EMC standards like MIL-STD-461. Additionally hardware based interference cancellation is also taken into account as the last opportunity for the antenna engineer to reach the required decoupling for undisturbed communication.

  18. Devices That May Interfere with Pacemakers

    MedlinePlus

    ... and the devices that may interfere with pulse generators. Carry your pacemaker ID card to prove that ... 3 watts) don't appear to damage pulse generators or affect how the pacemaker works. Technology is ...

  19. Automotive radar - investigation of mutual interference mechanisms

    NASA Astrophysics Data System (ADS)

    Goppelt, M.; Blöcher, H.-L.; Menzel, W.

    2010-09-01

    In the past mutual interference between automotive radar sensors has not been regarded as a major problem. With an increasing number of such systems, however, this topic is receiving more and more attention. The investigation of mutual interference and countermeasures is therefore one topic of the joint project "Radar on Chip for Cars" (RoCC) funded by the German Federal Ministry of Education and Research (BMBF). RoCC's goal is to pave the way for the development of high-performance, low-cost 79 GHz radar sensors based on Silicon-Germanium (SiGe) Monolithic Microwave Integrated Circuits (MMICs). This paper will present some generic interference scenarios and report on the current status of the analysis of interference mechanisms.

  20. Adaptive Development

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The goal of this research is to develop and demonstrate innovative adaptive seal technologies that can lead to dramatic improvements in engine performance, life, range, and emissions, and enhance operability for next generation gas turbine engines. This work is concentrated on the development of self-adaptive clearance control systems for gas turbine engines. Researchers have targeted the high-pressure turbine (HPT) blade tip seal location for following reasons: Current active clearance control (ACC) systems (e.g., thermal case-cooling schemes) cannot respond to blade tip clearance changes due to mechanical, thermal, and aerodynamic loads. As such they are prone to wear due to the required tight running clearances during operation. Blade tip seal wear (increased clearances) reduces engine efficiency, performance, and service life. Adaptive sealing technology research has inherent impact on all envisioned 21st century propulsion systems (e.g. distributed vectored, hybrid and electric drive propulsion concepts).

  1. Understanding conoscopic interference patterns in anisotropic crystals

    NASA Astrophysics Data System (ADS)

    Olorunsola, Oluwatobi Gabriel

    The interference patterns observed in conoscopy are important in studying the optical and geometrical properties of anisotropic materials. They have also been used to identify minerals and to explore the structure of biological tissues. In a conoscopic interferometer, an optically anisotropic specimen is placed between two crossed linear polarizers and illuminated by a convergent light beam. The interference patterns are produced because in an anisotropic material an incident light is split into two eigenwaves, namely the ordinary and the extraordinary waves. We report our work on the theoretical simulation and experimental observation of the conoscopic interference patterns in anisotropic crystals. In our simulation, the interference patterns are decomposed into fringes of isogyres and isochromates. For each light propagation direction inside the crystal there exist two eigenwaves that have their own characteristic velocities and vibration directions. The isogyres are obtained by computing the angle between the polarization of the incident light and the vibration directions of the two eigenwaves. The isochromates are obtained by computing the phase retardance between the two eigenwaves inside the crystal. The interference patterns are experimentally observed in several crystals, with their optic axes either parallel or perpendicular to their surfaces. An external electric field is applied to deform the crystals from uniaxial to biaxial. The results of our experimental observation agree well with our computer simulation. In conventional interferometers the isochromatic interference fringes are observed by using a circular polarizer and a circular analyzer, both constructed by a linear polarizer and a quarter wave plate. However, due to the dispersion of the quarter wave plates, the phase-retardance between the two light waves inside the quarter wave plates is wavelength-dependent, which results in different conoscopic interference patterns for different colors of

  2. Spatial-temporal control of interferences of multiple tunneling photoelectron wave packets

    NASA Astrophysics Data System (ADS)

    Li, Min; Geng, Ji-Wei; Liu, Ming-Ming; Zheng, Xu; Peng, Liang-You; Gong, Qihuang; Liu, Yunquan

    2015-07-01

    We theoretically study the control of the interferences of multiple tunneling photoelectron wave packets in both temporal and spatial domains by an orthogonally polarized two-color laser pulse. Profound carpetlike and stripelike interference patterns can be turned on or off in the momentum spectra using a weak streaking field at half the frequency of a strong fundamental field. The modulations of the interference patterns with respect to the relative phase between the two frequency components are well recaptured by both a semiclassical interference model and an ab initio simulation with numerically solving the time-dependent Schrödinger equation. We highlight the importance of the ionic Coulomb potential on the photoelectron angular distributions of atoms in the orthogonally polarized two-color pulses. It is shown that the interference induced by the forward rescattering trajectories is enhanced while the contribution of the direct trajectories is suppressed. This study offers alternative routes toward probing and controlling the ultrafast ionization dynamics of atoms and molecules.

  3. Theory and simulation of multi-channel interference (MCI) widely tunable lasers.

    PubMed

    Chen, Quanan; Lu, Qiaoyin; Guo, Weihua

    2015-07-13

    A novel design of an InP-based monolithic widely tunable laser, multi-channel interference (MCI) laser, is proposed and presented for the first time. The device is comprised of a gain section, a common phase section and a multi-channel interference section. The multi-channel interference section contains a 1x8 splitter based on cascaded 1 × 2 multi-mode interferometers (MMIs) and eight arms with unequal length difference. The rear part of each arm is integrated with a one-port multi-mode interference reflector (MIR). Mode selection of the MCI laser is realized by the constructive interference of the lights reflected back by the eight arms. Through optimizing the arm length difference, a tuning range of more than 40 nm covering the whole C band, a threshold current around 11.5 mA and an side-mode-suppression-ratio (SMSR) up to 48 dB have been predicted for this widely tunable laser. Detailed design principle and numerical simulation results are presented. PMID:26191863

  4. Interference Fit Life Factors for Roller Bearings

    NASA Technical Reports Server (NTRS)

    Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

    2008-01-01

    The effect of hoop stresses in reducing cylindrical roller bearing fatigue life was determined for various classes of inner ring interference fit. Calculations were performed for up to seven interference fit classes for each of ten bearing sizes. Each fit was taken at tightest, average and loosest values within the fit class for RBEC-5 tolerance, thus requiring 486 separate analyses. The hoop stresses were superimposed on the Hertzian principal stresses created by the applied radial load to calculate roller bearing fatigue life. The method was developed through a series of equations to calculate the life reduction for cylindrical roller bearings based on interference fit. All calculated lives are for zero initial bearing internal clearance. Any reduction in bearing clearance due to interference fit was compensated by increasing the initial (unmounted) clearance. Results are presented as tables and charts of life factors for bearings with light, moderate and heavy loads and interference fits ranging from extremely light to extremely heavy and for bearing accuracy class RBEC 5 (ISO class 5). Interference fits on the inner bearing ring of a cylindrical roller bearing can significantly reduce bearing fatigue life. In general, life factors are smaller (lower life) for bearings running under light load where the unfactored life is highest. The various bearing series within a particular bore size had almost identical interference fit life factors for a particular fit. The tightest fit at the high end of the RBEC-5 tolerance band defined in ANSI/ABMA shaft fit tables produces a life factor of approximately 0.40 for an inner-race maximum Hertz stress of 1200 MPa (175 ksi) and a life factor of 0.60 for an inner-race maximum Hertz stress of 2200 MPa (320 ksi). Interference fits also impact the maximum Hertz stress-life relation.

  5. Simulating interference and diffraction in instructional laboratories

    NASA Astrophysics Data System (ADS)

    Maurer, L.

    2013-03-01

    Studieshave shown that standard lectures and instructional laboratory experiments are not effective at teaching interference and diffraction. In response, the author created an interactive computer program that simulates interference and diffraction effects using the finite difference time domain method. The software allows students to easily control, visualize and quantitatively measure the effects. Students collected data from simulations as part of their laboratory exercise, and they performed well on a subsequent quiz, showing promise for this approach.

  6. Three-spin coherent oscillations and interference

    NASA Astrophysics Data System (ADS)

    Poulin-Lamarre, G.; Thorgrimson, J.; Studenikin, S. A.; Aers, G. C.; Kam, A.; Zawadzki, P.; Wasilewski, Z. R.; Sachrajda, A. S.

    2015-03-01

    We utilize magnetic field dependencies to identify two hitherto unobserved quantum interference processes in a triple quantum dot circuit. The first observation involves the interplay of Landau-Zener-Stückelberg behavior from two separate anticrossings between two energy levels that anticross twice as a function of a detuning parameter. The second process involves quantum interference between all-exchange and hyperfine qubits activated in a three-spin system.

  7. A new orientation-adaptive interpolation method.

    PubMed

    Wang, Qing; Ward, Rabab Kreidieh

    2007-04-01

    We propose an isophote-oriented, orientation-adaptive interpolation method. The proposed method employs an interpolation kernel that adapts to the local orientation of isophotes, and the pixel values are obtained through an oriented, bilinear interpolation. We show that, by doing so, the curvature of the interpolated isophotes is reduced, and, thus, zigzagging artifacts are largely suppressed. Analysis and experiments show that images interpolated using the proposed method are visually pleasing and almost artifact free. PMID:17405424

  8. Interference in the processing of adjunct control.

    PubMed

    Parker, Dan; Lago, Sol; Phillips, Colin

    2015-01-01

    Recent research on the memory operations used in language comprehension has revealed a selective profile of interference effects during memory retrieval. Dependencies such as subject-verb agreement show strong facilitatory interference effects from structurally inappropriate but feature-matching distractors, leading to illusions of grammaticality (Pearlmutter et al., 1999; Wagers et al., 2009; Dillon et al., 2013). In contrast, dependencies involving reflexive anaphors are generally immune to interference effects (Sturt, 2003; Xiang et al., 2009; Dillon et al., 2013). This contrast has led to the proposal that all anaphors that are subject to structural constraints are immune to facilitatory interference. Here we use an animacy manipulation to examine whether adjunct control dependencies, which involve an interpreted anaphoric relation between a null subject and its licensor, are also immune to facilitatory interference effects. Our results show reliable facilitatory interference in the processing of adjunct control dependencies, which challenges the generalization that anaphoric dependencies as a class are immune to such effects. To account for the contrast between adjunct control and reflexive dependencies, we suggest that variability within anaphora could reflect either an inherent primacy of animacy cues in retrieval processes, or differential degrees of match between potential licensors and the retrieval probe. PMID:26441723

  9. Investigation of Interference Models for RFID Systems.

    PubMed

    Zhang, Linchao; Ferrero, Renato; Gandino, Filippo; Rebaudengo, Maurizio

    2016-01-01

    The reader-to-reader collision in an RFID system is a challenging problem for communications technology. In order to model the interference between RFID readers, different interference models have been proposed, mainly based on two approaches: single and additive interference. The former only considers the interference from one reader within a certain range, whereas the latter takes into account the sum of all of the simultaneous interferences in order to emulate a more realistic behavior. Although the difference between the two approaches has been theoretically analyzed in previous research, their effects on the estimated performance of the reader-to-reader anti-collision protocols have not yet been investigated. In this paper, the influence of the interference model on the anti-collision protocols is studied by simulating a representative state-of-the-art protocol. The results presented in this paper highlight that the use of additive models, although more computationally intensive, is mandatory to improve the performance of anti-collision protocols. PMID:26861326

  10. Interference in the processing of adjunct control

    PubMed Central

    Parker, Dan; Lago, Sol; Phillips, Colin

    2015-01-01

    Recent research on the memory operations used in language comprehension has revealed a selective profile of interference effects during memory retrieval. Dependencies such as subject–verb agreement show strong facilitatory interference effects from structurally inappropriate but feature-matching distractors, leading to illusions of grammaticality (Pearlmutter et al., 1999; Wagers et al., 2009; Dillon et al., 2013). In contrast, dependencies involving reflexive anaphors are generally immune to interference effects (Sturt, 2003; Xiang et al., 2009; Dillon et al., 2013). This contrast has led to the proposal that all anaphors that are subject to structural constraints are immune to facilitatory interference. Here we use an animacy manipulation to examine whether adjunct control dependencies, which involve an interpreted anaphoric relation between a null subject and its licensor, are also immune to facilitatory interference effects. Our results show reliable facilitatory interference in the processing of adjunct control dependencies, which challenges the generalization that anaphoric dependencies as a class are immune to such effects. To account for the contrast between adjunct control and reflexive dependencies, we suggest that variability within anaphora could reflect either an inherent primacy of animacy cues in retrieval processes, or differential degrees of match between potential licensors and the retrieval probe. PMID:26441723

  11. Ethical Perspectives on RNA Interference Therapeutics

    PubMed Central

    Ebbesen, Mette; Jensen, Thomas G.; Andersen, Svend; Pedersen, Finn Skou

    2008-01-01

    RNA interference is a mechanism for controlling normal gene expression which has recently begun to be employed as a potential therapeutic agent for a wide range of disorders, including cancer, infectious diseases and metabolic disorders. Clinical trials with RNA interference have begun. However, challenges such as off-target effects, toxicity and safe delivery methods have to be overcome before RNA interference can be considered as a conventional drug. So, if RNA interference is to be used therapeutically, we should perform a risk-benefit analysis. It is ethically relevant to perform a risk-benefit analysis since ethical obligations about not inflicting harm and promoting good are generally accepted. But the ethical issues in RNA interference therapeutics not only include a risk-benefit analysis, but also considerations about respecting the autonomy of the patient and considerations about justice with regard to the inclusion criteria for participation in clinical trials and health care allocation. RNA interference is considered a new and promising therapeutic approach, but the ethical issues of this method have not been greatly discussed, so this article analyses these issues using the bioethical theory of principles of the American bioethicists, Tom L. Beauchamp and James F. Childress. PMID:18612370

  12. Antigen-specific suppression of inflammatory arthritis using liposomes.

    PubMed

    Capini, Christelle; Jaturanpinyo, Montree; Chang, Hsin-I; Mutalik, Srinivas; McNally, Alice; Street, Shayna; Steptoe, Raymond; O'Sullivan, Brendan; Davies, Nigel; Thomas, Ranjeny

    2009-03-15

    Existing therapies for rheumatoid arthritis and other autoimmune diseases are not Ag specific, which increases the likelihood of systemic toxicity. We show that egg phosphatidylcholine liposomes loaded with Ag (OVA or methylated BSA) and a lipophilic NF-kappaB inhibitor (curcumin, quercetin, or Bay11-7082) suppress preexisting immune responses in an Ag-specific manner. We injected loaded liposomes into mice primed with Ag or into mice suffering from Ag-induced inflammatory arthritis. The liposomes targeted APCs in situ, suppressing the cells' responsiveness to NF-kappaB and inducing Ag-specific FoxP3(+) regulatory T cells. This regulatory mechanism suppressed effector T cell responses and the clinical signs of full-blown Ag-induced arthritis. Thus, liposomes encapsulate Ags and NF-kappaB inhibitors stably and efficiently and could be readily adapted to deliver Ags and inhibitors for Ag-specific suppression of other autoimmune and allergic diseases. PMID:19265134

  13. Sweet corn hybrid influences outcomes of wild proso millet suppression with sethoxydim

    Technology Transfer Automated Retrieval System (TEKTRAN)

    he extent to which crop interference can reduce reliance on other forms of weed control are poorly known. Observed variation in weed suppressive ability among sweet corn hybrids, coupled with the need for new approaches to manage annual grasses, provide incentive to quantify the effect of crop hybr...

  14. Investigating Mechanisms of Suppression in Preschool Children with Specific Language Impairment

    ERIC Educational Resources Information Center

    Spaulding, Tammie J.

    2010-01-01

    Purpose: This study investigated 2 suppression mechanisms--(a) resistance to distracter interference and (b) inhibition of a prepotent response--in preschool children with specific language impairment (SLI) and their typically developing peers. Method: Twenty-two preschool children with SLI and 22 typically developing controls participated in this…

  15. Next generation fire suppressants

    NASA Technical Reports Server (NTRS)

    Brown, Jerry A.

    1995-01-01

    Spectrex, Inc., located in Cedar Grove, NJ is a manufacturer of fire detection and suppression equipment. Spectrex is one of the original pioneers in high speed fire detection and suppression systems for combat vehicles. Spectrex has installed fire suppressions systems in thousands of combat vehicles and ships throughout the world. Additionally, they manufacture flame explosion detectors, ship damage control systems, and optical gas and vapor detectors. The culmination of several years of research and development has recently produced an innovative electro-optical continuous monitoring systems called SharpEye 20/20I IR(sup 3) and SAFEYE that provide fast and reliable gas, vapor, aerosol, flame, and explosion detection. SharpEye 20/20I IR(sup 3) is a self-contained triple spectrum flame detector which scans for oscillating IR radiation (1 to 10 Hz) in the spectral bands ranging from 4.0 to 5.0 microns and uses programmed algorithms to check the ratio and correlation of data received by the three sensors to make the system highly immune to false alarms. It is extremely sensitive as it can detect a 1 x 1 square foot gasoline pan fire at 200 feet in less than 3 seconds. The sensitivity is user programmable, offering 4 ranges of detection. SAFEYE is comprised of a selected number of multispectral ban microprocessors controlled detectors which are in communication with one or more radiation sources that is projected along a 600 feet optical path. The signals from the selected narrow bands are processed and analyzed by highly sophisticated algorithms. It is ideal for high risk, remote, large areas such as petroleum and chemical manufacturing sites, waste dumps, aircraft cargo bays, and ship compartments. The SAFEYE will perform direct readings of the presence or rate of rise of concentrations of gases, vapors, or aerosols at the range of parts per million and provide alarms at various set points at different levels of concentrations.

  16. Next generation fire suppressants

    SciTech Connect

    Brown, J.A.

    1995-03-01

    Spectrex, Inc., located in Cedar Grove, NJ is a manufacturer of fire detection and suppression equipment. Spectrex is one of the original pioneers in high speed fire detection and suppression systems for combat vehicles. Spectrex has installed fire suppressions systems in thousands of combat vehicles and ships throughout the world. Additionally, they manufacture flame explosion detectors, ship damage control systems, and optical gas and vapor detectors. The culmination of several years of research and development has recently produced an innovative electro-optical continuous monitoring systems called SharpEye 20/20I IR(sup 3) and SAFEYE that provide fast and reliable gas, vapor, aerosol, flame, and explosion detection. SharpEye 20/20I IR(sup 3) is a self-contained triple spectrum flame detector which scans for oscillating IR radiation (1 to 10 Hz) in the spectral bands ranging from 4.0 to 5.0 microns and uses programmed algorithms to check the ratio and correlation of data received by the three sensors to make the system highly immune to false alarms. It is extremely sensitive as it can detect a 1 x 1 square foot gasoline pan fire at 200 feet in less than 3 seconds. The sensitivity is user programmable, offering 4 ranges of detection. SAFEYE is comprised of a selected number of multispectral band microprocessor controlled detectors which are in communication with one or more radiation sources that is projected along a 600 feet optical path. The signals from the selected narrow bands are processed and analyzed by highly sophisticated algorithms. It is ideal for high risk, remote, large areas such as petroleum and chemical manufacturing sites, waste dumps, aircraft cargo bays, and ship compartments. The SAFEYE will perform direct readings of the presence or rate of rise of concentrations of gases, vapors, or aerosols at the range of parts per million and provide alarms at various set points at different levels of concentrations.

  17. Suppression of quantum phase interference in the molecular magnet Fe8 with dipolar-dipolar interaction

    NASA Astrophysics Data System (ADS)

    Chen, Zhi-De; Liang, J.-Q.; Shen, Shun-Qing

    2002-09-01

    Renormalized tunnel splitting with a finite distribution in the biaxial spin model for molecular magnets is obtained by taking into account the dipolar interaction of enviromental spins. Oscillation of the resonant tunnel splitting with a transverse magnetic field along the hard axis is smeared by the finite distribution, which subsequently affects the quantum steps of the hysteresis curve evaluated in terms of the modified Landau-Zener model of spin flipping induced by the sweeping field. We conclude that the dipolar-dipolar interaction drives decoherence of quantum tunneling in the molecular magnet Fe8, which explains why the quenching points of tunnel splitting between odd and even resonant tunneling predicted theoretically were not observed experimentally.

  18. RNA Interference Screen to Identify Kinases That Suppress Rescue of ΔF508-CFTR*

    PubMed Central

    Trzcińska-Daneluti, Agata M.; Chen, Anthony; Nguyen, Leo; Murchie, Ryan; Jiang, Chong; Moffat, Jason; Pelletier, Lawrence; Rotin, Daniela

    2015-01-01

    Cystic Fibrosis (CF) is an autosomal recessive disorder caused by mutations in the gene encoding the Cystic fibrosis transmembrane conductance regulator (CFTR). ΔF508-CFTR, the most common disease-causing CF mutant, exhibits folding and trafficking defects and is retained in the endoplasmic reticulum, where it is targeted for proteasomal degradation. To identify signaling pathways involved in ΔF508-CFTR rescue, we screened a library of endoribonuclease-prepared short interfering RNAs (esiRNAs) that target ∼750 different kinases and associated signaling proteins. We identified 20 novel suppressors of ΔF508-CFTR maturation, including the FGFR1. These were subsequently validated by measuring channel activity by the YFP halide-sensitive assay following shRNA-mediated knockdown, immunoblotting for the mature (band C) ΔF508-CFTR and measuring the amount of surface ΔF508-CFTR by ELISA. The role of FGFR signaling on ΔF508-CFTR trafficking was further elucidated by knocking down FGFRs and their downstream signaling proteins: Erk1/2, Akt, PLCγ-1, and FRS2. Interestingly, inhibition of FGFR1 with SU5402 administered to intestinal organoids (mini-guts) generated from the ileum of ΔF508-CFTR homozygous mice resulted in a robust ΔF508-CFTR rescue. Moreover, combination of SU5402 and VX-809 treatments in cells led to an additive enhancement of ΔF508-CFTR rescue, suggesting these compounds operate by different mechanisms. Chaperone array analysis on human bronchial epithelial cells harvested from ΔF508/ΔF508-CFTR transplant patients treated with SU5402 identified altered expression of several chaperones, an effect validated by their overexpression or knockdown experiments. We propose that FGFR signaling regulates specific chaperones that control ΔF508-CFTR maturation, and suggest that FGFRs may serve as important targets for therapeutic intervention for the treatment of CF. PMID:25825526

  19. Eye Movement Suppression Interferes with Construction of Object-Centered Spatial Reference Frames in Working Memory

    ERIC Educational Resources Information Center

    Wallentin, Mikkel; Kristensen, Line Burholt; Olsen, Jacob Hedeager; Nielsen, Andreas Hojlund

    2011-01-01

    The brain's frontal eye fields (FEF), responsible for eye movement control, are known to be involved in spatial working memory (WM). In a previous fMRI experiment (Wallentin, Roepstorff & Burgess, Neuropsychologia, 2008) it was found that FEF activation was primarily related to the formation of an object-centered, rather than egocentric, spatial…

  20. Suppression of flutter

    NASA Technical Reports Server (NTRS)

    Nissim, E. (Inventor)

    1973-01-01

    An active aerodynamic control system to control flutter over a large range of oscillatory frequencies is described. The system is not affected by mass, stiffness, elastic axis, or center of gravity location of the system, mode of vibration, or Mach number. The system consists of one or more pairs of leading edge and trailing edge hinged or deformable control surfaces, each pair operated in concert by a stability augmentation system. Torsion and bending motions are sensed and converted by the stability augmentation system into leading and trailing edge control surface deflections which produce lift forces and pitching moments to suppress flutter.

  1. Adapting Animals.

    ERIC Educational Resources Information Center

    Wedman, John; Wedman, Judy

    1985-01-01

    The "Animals" program found on the Apple II and IIe system master disk can be adapted for use in the mathematics classroom. Instructions for making the necessary changes and suggestions for using it in lessons related to geometric shapes are provided. (JN)

  2. Adaptive Thresholds

    SciTech Connect

    Bremer, P. -T.

    2014-08-26

    ADAPT is a topological analysis code that allow to compute local threshold, in particular relevance based thresholds for features defined in scalar fields. The initial target application is vortex detection but the software is more generally applicable to all threshold based feature definitions.

  3. Adaptive homeostasis.

    PubMed

    Davies, Kelvin J A

    2016-06-01

    Homeostasis is a central pillar of modern Physiology. The term homeostasis was invented by Walter Bradford Cannon in an attempt to extend and codify the principle of 'milieu intérieur,' or a constant interior bodily environment, that had previously been postulated by Claude Bernard. Clearly, 'milieu intérieur' and homeostasis have served us well for over a century. Nevertheless, research on signal transduction systems that regulate gene expression, or that cause biochemical alterations to existing enzymes, in response to external and internal stimuli, makes it clear that biological systems are continuously making short-term adaptations both to set-points, and to the range of 'normal' capacity. These transient adaptations typically occur in response to relatively mild changes in conditions, to programs of exercise training, or to sub-toxic, non-damaging levels of chemical agents; thus, the terms hormesis, heterostasis, and allostasis are not accurate descriptors. Therefore, an operational adjustment to our understanding of homeostasis suggests that the modified term, Adaptive Homeostasis, may be useful especially in studies of stress, toxicology, disease, and aging. Adaptive Homeostasis may be defined as follows: 'The transient expansion or contraction of the homeostatic range in response to exposure to sub-toxic, non-damaging, signaling molecules or events, or the removal or cessation of such molecules or events.' PMID:27112802

  4. Prefrontal inhibition of threat processing reduces working memory interference

    PubMed Central

    Clarke, Robert; Johnstone, Tom

    2013-01-01

    Bottom-up processes can interrupt ongoing cognitive processing in order to adaptively respond to emotional stimuli of high potential significance, such as those that threaten wellbeing. However it is vital that this interference can be modulated in certain contexts to focus on current tasks. Deficits in the ability to maintain the appropriate balance between cognitive and emotional demands can severely impact on day-to-day activities. This fMRI study examined this interaction between threat processing and cognition; 18 adult participants performed a visuospatial working memory (WM) task with two load conditions, in the presence and absence of anxiety induction by threat of electric shock. Threat of shock interfered with performance in the low cognitive load condition; however interference was eradicated under high load, consistent with engagement of emotion regulation mechanisms. Under low load the amygdala showed significant activation to threat of shock that was modulated by high cognitive load. A directed top-down control contrast identified two regions associated with top-down control; ventrolateral PFC and dorsal ACC. Dynamic causal modeling provided further evidence that under high cognitive load, top-down inhibition is exerted on the amygdala and its outputs to prefrontal regions. Additionally, we hypothesized that individual differences in a separate, non-emotional top-down control task would predict the recruitment of dorsal ACC and ventrolateral PFC during top-down control of threat. Consistent with this, performance on a separate dichotic listening task predicted dorsal ACC and ventrolateral PFC activation during high WM load under threat of shock, though activation in these regions did not directly correlate with WM performance. Together, the findings suggest that under high cognitive load and threat, top-down control is exerted by dACC and vlPFC to inhibit threat processing, thus enabling WM performance without threat-related interference. PMID

  5. Modified Beamformers for Coherent Source Region Suppression

    PubMed Central

    Sekihara, Kensuke; Nagarajan, Srikantan S.

    2011-01-01

    Many tomographic source localization algorithms used in biomagnetic imaging assume, explicitly or sometimes implicitly, that the source activity at different brain locations are either independent or that the correlation structure between sources is known. Among these algorithms is a class of adaptive spatial filters known as beamformers, which have superior spatiotemporal resolution abilities. The performance of beamformers is robust to weakly coherent sources. However, these algorithms are extremely sensitive to the presence of strongly coherent sources. A frequent mode of failure in beamformers occurs with reconstruction of auditory evoked fields (AEFs), in which bilateral auditory cortices are highly coherent in their activation. Here, we present a novel beamformer that suppresses activation from regions with interfering coherent sources. First, a volume containing the interfering sources is defined. The lead field matrix for this volume is computed and reduced into a few significant columns using singular value decomposition (SVD). A vector beamformer is then constructed by rejecting the contribution of sources in the suppression region while allowing for source reconstruction at other specified regions. Performance of this algorithm was first validated with simulated data. Subsequent tests of this modified beamformer were performed on bilateral AEF data. An unmodified vector beamformer using whole head coverage misplaces the source medially. After defining a suppression region containing the temporal cortex on one side, the described method consistently results in clear focal activations at expected regions of the contralateral superior temporal plane. PMID:16830939

  6. Recombination Suppression by Heterozygous Robertsonian Chromosomes in the Mouse

    PubMed Central

    Davisson, M. T.; Akeson, E. C.

    1993-01-01

    Robertsonian chromosomes are metacentric chromosomes formed by the joining of two telocentric chromosomes at their centromere ends. Many Robertsonian chromosomes of the mouse suppress genetic recombination near the centromere when heterozygous. We have analyzed genetic recombination and meiotic pairing in mice heterozygous for Robertsonian chromosomes and genetic markers to determine (1) the reason for this recombination suppression and (2) whether there are any consistent rules to predict which Robertsonian chromosomes will suppress recombination. Meiotic pairing was analyzed using synaptonemal complex preparations. Our data provide evidence that the underlying mechanism of recombination suppression is mechanical interference in meiotic pairing between Robertsonian chromosomes and their telocentric partners. The fact that recombination suppression is specific to individual Robertsonian chromosomes suggests that the pairing delay is caused by minor structural differences between the Robertsonian chromosomes and their telocentric homologs and that these differences arise during Robertsonian formation. Further understanding of this pairing delay is important for mouse mapping studies. In 10 mouse chromosomes (3, 4, 5, 6, 8, 9, 10, 11, 15 and 19) the distances from the centromeres to first markers may still be underestimated because they have been determined using only Robertsonian chromosomes. Our control linkage studies using C-band (heterochromatin) markers for the centromeric region provide improved estimates for the centromere-to-first-locus distance in mouse chromosomes 1, 2 and 16. PMID:8454207

  7. Juggling reveals a decisional component to tactile suppression.

    PubMed

    Juravle, Georgiana; Spence, Charles

    2011-08-01

    Goal-directed movements are characterized by sensory suppression, that is, by decreased sensitivity to tactile stimuli. In the present study, we investigated tactile suppression during movement using a complex motor task: basic 3-ball juggling. It was hypothesized that a decrease in tactile sensitivity would be observed, together with a shift in participants' response bias while juggling. In a first experiment, participants had to detect a short gap in an otherwise continuous vibratory stimulus, which was delivered to their wrist under conditions of rest or else while juggling. In a second experiment, participants detected a short time gap in a continuous auditory signal, under the same conditions. In a final control experiment performed at rest, participants detected a short time gap in an auditory or tactile signal. In an additional condition, the detection of a gap in tactile stimulation was required under conditions of intramodal tactile interference. Participants were significantly less sensitive to detect a gap in tactile stimulation whilst juggling. Most importantly, these results were paired with a significant shift toward participants adopting a more conservative criterion when responding to the presence of the gap (i.e. they were more likely to say that a gap was not present). Taken together, these results demonstrate movement-related tactile sensory suppression and point to a decisional component in tactile suppression, thus suggesting that tactile suppression could already be triggered in the brain ahead of the motor command. PMID:21717097

  8. Skeletal Muscle Hypertrophy with Concurrent Exercise Training: Contrary Evidence for an Interference Effect.

    PubMed

    Murach, Kevin A; Bagley, James R

    2016-08-01

    Over the last 30+ years, it has become axiomatic that performing aerobic exercise within the same training program as resistance exercise (termed concurrent exercise training) interferes with the hypertrophic adaptations associated with resistance exercise training. However, a close examination of the literature reveals that the interference effect of concurrent exercise training on muscle growth in humans is not as compelling as previously thought. Moreover, recent studies show that, under certain conditions, concurrent exercise may augment resistance exercise-induced hypertrophy in healthy human skeletal muscle. The purpose of this article is to outline the contrary evidence for an acute and chronic interference effect of concurrent exercise on skeletal muscle growth in humans and provide practical literature-based recommendations for maximizing hypertrophy when training concurrently. PMID:26932769

  9. Akima splines for minimization of breathing interference in aortic rheography data

    NASA Astrophysics Data System (ADS)

    Tsoy, Maria O.; Stiukhina, Elena S.; Klochkov, Victor A.; Postnov, Dmitry E.

    2015-03-01

    The elimination of low-frequency noise of breath and motion artifacts is one of the most difficult challenges of preprocessing rheographic signal. The data filtering is the conventional way to separate useful signal from noise and interferences. Conventionally, linear filtering is used to easy design and implementation. However, in some cases such techniques are difficult, if possible, to apply, since the data frequency range is overlapped with one of interferences. Specifically, it happens in aortic rheography, where some breathing process and pulmonary blood flow contributions are unavoidable. We suggest an alternative approach for breathing interference reduction, based on adaptive reconstruction of baseline deviation. Specifically, the computational scheme based on multiple calculation of Akima splines is suggested, implemented using C# language and validated using surrogate data. The applications of proposed technique to the real data processing deliver the better quality of aortic valve opening detection.

  10. Planck-suppressed operators

    SciTech Connect

    Assassi, Valentin; Baumann, Daniel; Green, Daniel; McAllister, Liam E-mail: dbaumann@damtp.cam.ac.uk E-mail: mcallister@cornell.edu

    2014-01-01

    We show that the recent Planck limits on primordial non-Gaussianity impose strong constraints on light hidden sector fields coupled to the inflaton via operators suppressed by a high mass scale Λ. We study a simple effective field theory in which a hidden sector field is coupled to a shift-symmetric inflaton via arbitrary operators up to dimension five. Self-interactions in the hidden sector lead to non-Gaussianity in the curvature perturbations. To be consistent with the Planck limit on local non-Gaussianity, the coupling to any hidden sector with light fields and natural cubic couplings must be suppressed by a very high scale Λ > 10{sup 5}H. Even if the hidden sector has Gaussian correlations, nonlinearities in the mixing with the inflaton still lead to non-Gaussian curvature perturbations. In this case, the non-Gaussianity is of the equilateral or orthogonal type, and the Planck data requires Λ > 10{sup 2}H.

  11. Spin-independent interferences and spin-dependent interactions with scalar dark matter

    NASA Astrophysics Data System (ADS)

    Martinez, R.; Ochoa, F.

    2016-05-01

    We explore mechanisms of interferences under which the spin-independent interaction in the scattering of scalar dark matter with nucleus is suppressed in relation to the spin-dependent one. We offer a detailed derivation of the nuclear amplitudes based on the interactions with quarks in the framework of a nonuniversal U(1)' extension of the standard model. By assuming a range of parameters compatible with collider searches, electroweak observables and dark matter abundance, we find scenarios for destructive interferences with and without isospin symmetry. The model reveals solutions with mutually interfering scalar particles, canceling the effective spin-independent coupling with only scalar interactions, which requires an extra Higgs boson with mass M H > 125 GeV. The model also possesses scenarios with only vector interactions through two neutral gauge bosons, Z and Z', which do not exhibit interference effects. Due to the nonuniversality of the U(1)' symmetry, we distinguish two family structures of the quark sector with different numerical predictions. In one case, we obtain cross sections that pass all the Xenon-based detector experiments. In the other case, limits from LUX experiment enclose an exclusion region for dark matter between 9 and 800 GeV. We examine a third scenario with isospin-violating couplings where interferences between scalar and vector boson exchanges cancel the scattering. We provide solutions where interactions with Xenon-based detectors is suppressed for light dark matter, below 6 GeV, while interactions with Germanium- and Silicon-based detectors exhibit solutions up to the regions of interest for positive signals reported by CoGeNT and CDMS-Si experiments, and compatible with the observed DM relic density for DM mass in the range 8 .3-10 GeV. Spin-dependent interactions become the dominant source of scattering around the interference regions, where Maxwellian speed distribution is considered.

  12. Mood states influence cognitive control: the case of conflict adaptation.

    PubMed

    Schuch, Stefanie; Koch, Iring

    2015-09-01

    Conflict adaptation can be measured by the "congruency sequence effect", denoting the reduction of congruency effects after incongruent trials (where response conflict occurs) relative to congruent trials (without response conflict). Recently, it has been reported that conflict adaptation is larger in negative mood than in positive mood (van Steenbergen et al., Psychological Science 21:1629-1634, 2010). We conducted two experiments further investigating this important finding. Two different interference paradigms were applied to measure conflict adaptation: Experiment 1 was a Flanker task, Experiment 2 was a Stroop-like task. To get as pure a measure of conflict adaptation as possible, we minimized the influence of trial-to-trial priming effects by excluding all kinds of stimulus repetitions. Mood states were induced by presenting film clips with emotional content prior to the interference task. Three mood states were manipulated between subjects: amused, anxious, and sad. Across both interference paradigms, we consistently found conflict adaptation in negative, but not in positive mood. Taken together with van Steenbergen et al. (Psychological Science 21:1629-1634, 2010) findings, the results suggest that the negative-mood-triggered increase in conflict adaptation is a general phenomenon that occurs independently of the particular mood-induction procedure and interference paradigm involved. PMID:25100233

  13. A New Method to Cancel RFI---The Adaptive Filter

    NASA Astrophysics Data System (ADS)

    Bradley, R.; Barnbaum, C.

    1996-12-01

    An increasing amount of precious radio frequency spectrum in the VHF, UHF, and microwave bands is being utilized each year to support new commercial and military ventures, and all have the potential to interfere with radio astronomy observations. Some radio spectral lines of astronomical interest occur outside the protected radio astronomy bands and are unobservable due to heavy interference. Conventional approaches to deal with RFI include legislation, notch filters, RF shielding, and post-processing techniques. Although these techniques are somewhat successful, each suffers from insufficient interference cancellation. One concept of interference excision that has not been used before in radio astronomy is adaptive interference cancellation. The concept of adaptive interference canceling was first introduced in the mid-1970s as a way to reduce unwanted noise in low frequency (audio) systems. Examples of such systems include the canceling of maternal ECG in fetal electrocardiography and the reduction of engine noise in the passenger compartment of automobiles. Only recently have high-speed digital filter chips made adaptive filtering possible in a bandwidth as large a few megahertz, finally opening the door to astronomical uses. The system consists of two receivers: the main beam of the radio telescope receives the desired signal corrupted by RFI coming in the sidelobes, and the reference antenna receives only the RFI. The reference antenna is processed using a digital adaptive filter and then subtracted from the signal in the main beam, thus producing the system output. The weights of the digital filter are adjusted by way of an algorithm that minimizes, in a least-squares sense, the power output of the system. Through an adaptive-iterative process, the interference canceler will lock onto the RFI and the filter will adjust itself to minimize the effect of the RFI at the system output. We are building a prototype 100 MHz receiver and will measure the cancellation

  14. Anomalous adaptive conditions associated with strabismus.

    PubMed

    Verma, Arun

    2007-01-01

    Anomalous adaptive conditions (AAC) associated with strabismus include: suppression, amblyopia, abnormal retinal correspondence, eccentric fixation, retinal rivalry, horror fusionis, and suspension. This article poses the hypothesis that AAC, in certain cases, may be the cause of strabismus rather than the result of strabismus. PMID:17984497

  15. Autobiographical Thinking Interferes with Episodic Memory Consolidation

    PubMed Central

    Craig, Michael; Della Sala, Sergio; Dewar, Michaela

    2014-01-01

    New episodic memories are retained better if learning is followed by a few minutes of wakeful rest than by the encoding of novel external information. Novel encoding is said to interfere with the consolidation of recently acquired episodic memories. Here we report four experiments in which we examined whether autobiographical thinking, i.e. an ‘internal’ memory activity, also interferes with episodic memory consolidation. Participants were presented with three wordlists consisting of common nouns; one list was followed by wakeful rest, one by novel picture encoding and one by autobiographical retrieval/future imagination, cued by concrete sounds. Both novel encoding and autobiographical retrieval/future imagination lowered wordlist retention significantly. Follow-up experiments demonstrated that the interference by our cued autobiographical retrieval/future imagination delay condition could not be accounted for by the sound cues alone or by executive retrieval processes. Moreover, our results demonstrated evidence of a temporal gradient of interference across experiments. Thus, we propose that rich autobiographical retrieval/future imagination hampers the consolidation of recently acquired episodic memories and that such interference is particularly likely in the presence of external concrete cues. PMID:24736665

  16. Pattern-integrated interference lithography instrumentation

    NASA Astrophysics Data System (ADS)

    Burrow, G. M.; Leibovici, M. C. R.; Kummer, J. W.; Gaylord, T. K.

    2012-06-01

    Multi-beam interference (MBI) provides the ability to form a wide range of sub-micron periodic optical-intensity distributions with applications to a variety of areas, including photonic crystals (PCs), nanoelectronics, biomedical structures, optical trapping, metamaterials, and numerous subwavelength structures. Recently, pattern-integrated interference lithography (PIIL) was presented as a new lithographic method that integrates superposed pattern imaging with interference lithography in a single-exposure step. In the present work, the basic design and systematic implementation of a pattern-integrated interference exposure system (PIIES) is presented to realize PIIL by incorporating a projection imaging capability in a novel three-beam interference configuration. A fundamental optimization methodology is presented to model the system and predict MBI-patterning performance. To demonstrate the PIIL method, a prototype PIIES experimental configuration is presented, including detailed alignment techniques and experimental procedures. Examples of well-defined PC structures, fabricated with a PIIES prototype, are presented to demonstrate the potential of PIIL for fabricating dense integrated optical circuits, as well as numerous other subwavelength structures.

  17. Phonon-Mediated Nonclassical Interference in Diamond.

    PubMed

    England, Duncan G; Fisher, Kent A G; MacLean, Jean-Philippe W; Bustard, Philip J; Heshami, Khabat; Resch, Kevin J; Sussman, Benjamin J

    2016-08-12

    Quantum interference of single photons is a fundamental aspect of many photonic quantum processing and communication protocols. Interference requires that the multiple pathways through an interferometer be temporally indistinguishable to within the coherence time of the photon. In this Letter, we use a diamond quantum memory to demonstrate interference between quantum pathways, initially temporally separated by many multiples of the optical coherence time. The quantum memory can be viewed as a light-matter beam splitter, mapping a THz-bandwidth single photon to a variable superposition of the output optical mode and stored phononic mode. Because the memory acts both as a beam splitter and as a buffer, the relevant coherence time for interference is not that of the photon, but rather that of the memory. We use this mechanism to demonstrate nonclassical single-photon and two-photon interference between quantum pathways initially separated by several picoseconds, even though the duration of the photons themselves is just ∼250  fs. PMID:27563963

  18. Remote sensing of nearshore wave interference

    NASA Astrophysics Data System (ADS)

    Smit, P. B.; Bland, R.; Janssen, T. T.; Laughlin, B.

    2016-05-01

    Wave focusing of energetic swell fields can result in small-scale variations associated with coherent interference that can be important for nearshore circulation and beach dynamics. However, coherent interference is difficult to measure with conventional in situ instruments and is not accounted for in operational wave models. As a result, such effects are generally ignored. In this work, we analyze X-band radar observations collected at Ocean Beach, San Francisco using a Wigner-Ville or coupled-mode spectrum, to show how long-dwell remote sensing technology allows us to identify coherent wave interference. Our analysis demonstrates that during energetic swell events, the nearshore wave field consists of two noncollinear, but coherent, swell patterns that originate from the same offshore source but are directionally separated due to refraction over the San Francisco Bar. The length scale of the associated alongshore wave height variability (200 m) is consistent with the wavenumber separation obtained from the coupled mode analysis. This confirms that the small-scale variability is primarily due to coherent interference. In addition, our analysis shows that the shoreline exhibits a strong localized response near the radar site on the 200 m scale, which suggests that coherent interference effects can affect wave-driven nearshore transport processes and localized erosion.

  19. [Interference of ethylene glycol on lactate assays].

    PubMed

    Graïne, H; Toumi, K; Roullier, V; Capeau, J; Lefèvre, G

    2007-01-01

    Ethylene glycol is broken down to three main organic acids: glycolic acid, glyoxylic acid and oxalic acid which cause severe metabolic acidosis. Effect of these three acids on lactate assays was evaluated in five blood gas analysers and two clinical chemistry analysers. For all systems, no influence of oxalic acid on lactate results could be demonstrated. No interference of glycolic acid could be observed on lactate assay performed with Rapid Lab 1265 (R: 104,9 +/- 12,1%), Vitros 950 (R: 105,7 +/- 5,3 %) and Architect ci8200 (R: 104,9 +/- 4,7%), but on the contrary, CCX 4, OMNI S, ABL 725 and 825 demonstrated a concentration-dependent interference. No interference of glyoxylic acid could be observed with Vitros 950, but a positive interference could be observed with ABL 725 and 825, OMNI S, CCX4 and Architect ci8200 A linear relationship between apparent lactate concentration found with ABL 725 and 825, OMNI S, CCX 4, and glyoxylic acid could be observed (0,94 < r < 0,99), a weaker interference being observed with Rapid Lab 1265 and Architect ci 8200. Our results demonstrated that in case of ethylene glycol poisoning, cautious interpretation of lactate assay should be done, since wrong results of lactacidemia could lead to misdiagnostic and delay patient treatment. PMID:17627925

  20. General Quantum Interference Principle and Duality Computer

    NASA Astrophysics Data System (ADS)

    Long, Gui-Lu

    2006-05-01

    In this article, we propose a general principle of quantum interference for quantum system, and based on this we propose a new type of computing machine, the duality computer, that may outperform in principle both classical computer and the quantum computer. According to the general principle of quantum interference, the very essence of quantum interference is the interference of the sub-waves of the quantum system itself. A quantum system considered here can be any quantum system: a single microscopic particle, a composite quantum system such as an atom or a molecule, or a loose collection of a few quantum objects such as two independent photons. In the duality computer, the wave of the duality computer is split into several sub-waves and they pass through different routes, where different computing gate operations are performed. These sub-waves are then re-combined to interfere to give the computational results. The quantum computer, however, has only used the particle nature of quantum object. In a duality computer, it may be possible to find a marked item from an unsorted database using only a single query, and all NP-complete problems may have polynomial algorithms. Two proof-of-the-principle designs of the duality computer are presented: the giant molecule scheme and the nonlinear quantum optics scheme. We also propose thought experiment to check the related fundamental issues, the measurement efficiency of a partial wave function.

  1. Interference of light from independent sources

    SciTech Connect

    Pegg, David T.

    2006-12-15

    We extend and generalize previous work on the interference of light from independent cavities that began with the suggestion of Pfleegor and Mandel [Phys. Rev. 159, 1084 (1967)] that their observed interference of laser beams should not be associated too closely with particular states of the beams but more with the detection process itself. In particular we examine how the detection of interference induces a nonrandom-phase difference between internal cavity states with initial random phases for a much broader range of such states than has previously been considered. We find that a subsequent interference measurement should give results consistent with the induced phase difference. The inclusion of more cavities in the interference measurements enables the construction in principle of a laboratory in the sense used by Aharonov and Susskind, made up of cavity fields that can serve as frames of phase reference. We also show reasonably simply how intrinsic phase coherence of a beam of light leaking from a single cavity arises for any internal cavity state, even a photon number state. Although the work presented here may have some implications for the current controversy over whether or not a typical laboratory laser produces a coherent state, it is not the purpose of this paper to enter this controversy; rather it is to examine the interesting quantum physics that arises for cavities with more general internal states.

  2. Connector adapter

    NASA Technical Reports Server (NTRS)

    Hacker, Scott C. (Inventor); Dean, Richard J. (Inventor); Burge, Scott W. (Inventor); Dartez, Toby W. (Inventor)

    2007-01-01

    An adapter for installing a connector to a terminal post, wherein the connector is attached to a cable, is presented. In an embodiment, the adapter is comprised of an elongated collet member having a longitudinal axis comprised of a first collet member end, a second collet member end, an outer collet member surface, and an inner collet member surface. The inner collet member surface at the first collet member end is used to engage the connector. The outer collet member surface at the first collet member end is tapered for a predetermined first length at a predetermined taper angle. The collet includes a longitudinal slot that extends along the longitudinal axis initiating at the first collet member end for a predetermined second length. The first collet member end is formed of a predetermined number of sections segregated by a predetermined number of channels and the longitudinal slot.

  3. Sleep facilitates long-term face adaptation.

    PubMed

    Ditye, Thomas; Javadi, Amir Homayoun; Carbon, Claus-Christian; Walsh, Vincent

    2013-10-22

    Adaptation is an automatic neural mechanism supporting the optimization of visual processing on the basis of previous experiences. While the short-term effects of adaptation on behaviour and physiology have been studied extensively, perceptual long-term changes associated with adaptation are still poorly understood. Here, we show that the integration of adaptation-dependent long-term shifts in neural function is facilitated by sleep. Perceptual shifts induced by adaptation to a distorted image of a famous person were larger in a group of participants who had slept (experiment 1) or merely napped for 90 min (experiment 2) during the interval between adaptation and test compared with controls who stayed awake. Participants' individual rapid eye movement sleep duration predicted the size of post-sleep behavioural adaptation effects. Our data suggest that sleep prevented decay of adaptation in a way that is qualitatively different from the effects of reduced visual interference known as 'storage'. In the light of the well-established link between sleep and memory consolidation, our findings link the perceptual mechanisms of sensory adaptation--which are usually not considered to play a relevant role in mnemonic processes--with learning and memory, and at the same time reveal a new function of sleep in cognition. PMID:23986109

  4. Optical compensation of distorted data image caused by interference fringe distortion in holographic data storage.

    PubMed

    Muroi, Tetsuhiko; Kinoshita, Nobuhiro; Ishii, Norihiko; Kamijo, Koji; Shimidzu, Naoki

    2009-07-01

    Photopolymer materials shrink because of photopolymerization. This shrinkage distorts the recorded interference fringes in a medium made of such material, which in turn degrades the reconstructed image quality. Adaptive optics controlled by a genetic algorithm was developed to optimize the wavefront of the reference beam while reproducing in order to compensate for the interference fringe distortion. We defined a fitness measure for this genetic algorithm that involves the mean brightness and coefficients of the variations of bit data "1" and "0". In an experiment, the adaptive optics improved the reconstructed image to the extent that data could be reproduced from the entire area of the image, and the signal to noise ratio of the reproduced data could be improved. PMID:19571923

  5. Adaptive sampler

    DOEpatents

    Watson, Bobby L.; Aeby, Ian

    1982-01-01

    An adaptive data compression device for compressing data having variable frequency content, including a plurality of digital filters for analyzing the content of the data over a plurality of frequency regions, a memory, and a control logic circuit for generating a variable rate memory clock corresponding to the analyzed frequency content of the data in the frequency region and for clocking the data into the memory in response to the variable rate memory clock.

  6. Adaptive sampler

    DOEpatents

    Watson, B.L.; Aeby, I.

    1980-08-26

    An adaptive data compression device for compressing data is described. The device has a frequency content, including a plurality of digital filters for analyzing the content of the data over a plurality of frequency regions, a memory, and a control logic circuit for generating a variable rate memory clock corresponding to the analyzed frequency content of the data in the frequency region and for clocking the data into the memory in response to the variable rate memory clock.

  7. Mitigation of 50-60 Hz power line interference in geophysical data

    NASA Astrophysics Data System (ADS)

    Cohen, M. B.; Said, R. K.; Inan, U. S.

    2010-12-01

    The analysis of ELF/VLF radio data has broad applications for ionospheric and magnetospheric phenomena, lightning activity, long-range communications, and geophysical prospecting. However, recordings of ELF/VLF data on the ground are adversely affected by the presence of electromagnetic fields from 50-60 Hz power lines, whose harmonics can extend to many kilohertz and interfere with the detection of natural and man-made signals. Removal of this interference is complicated by the time-varying fundamental frequency of power lines and strongly varying characteristics across different power grids. We discuss two methods for isolation and then subtraction of this interference, by an adaptive filtering technique and with least squares matrix analysis. Methods for estimating the time-varying frequency are also discussed. A few variants of these techniques are applied both to simulated data and then to real data. It is found that least squares isolation gives superior results, although the adaptive filter is potentially more effective for poorly behaved power line interference with rapidly changing fundamental frequencies as well as being computationally more efficient.

  8. Adaptive antennas

    NASA Astrophysics Data System (ADS)

    Barton, P.

    1987-04-01

    The basic principles of adaptive antennas are outlined in terms of the Wiener-Hopf expression for maximizing signal to noise ratio in an arbitrary noise environment; the analogy with generalized matched filter theory provides a useful aid to understanding. For many applications, there is insufficient information to achieve the above solution and thus non-optimum constrained null steering algorithms are also described, together with a summary of methods for preventing wanted signals being nulled by the adaptive system. The three generic approaches to adaptive weight control are discussed; correlation steepest descent, weight perturbation and direct solutions based on sample matrix conversion. The tradeoffs between hardware complexity and performance in terms of null depth and convergence rate are outlined. The sidelobe cancellor technique is described. Performance variation with jammer power and angular distribution is summarized and the key performance limitations identified. The configuration and performance characteristics of both multiple beam and phase scan array antennas are covered, with a brief discussion of performance factors.

  9. Delaying Interference Training Has Equivalent Effects in Various Pavlovian Interference Paradigms

    ERIC Educational Resources Information Center

    Powell, Elizabeth J.; Escobar, Martha; Kimble, Whitney

    2013-01-01

    Spontaneous recovery in extinction appears to be inversely related to the acquisition-to-extinction interval, but it remains unclear why this is the case. Rat subjects trained with one of three interference paradigms exhibited less spontaneous recovery of the original response after delayed than immediate interference, regardless of whether…

  10. An experimental SMI adaptive antenna array for weak interfering signals

    NASA Technical Reports Server (NTRS)

    Dilsavor, R. L.; Gupta, I. J.

    1989-01-01

    A modified sample matrix inversion (SMI) algorithm designed to increase the suppression of weak interference is implemented on an existing experimental array system. The algorithm itself is fully described as are a number of issues concerning its implementation and evaluation, such as sample scaling, snapshot formation, weight normalization, power calculation, and system calibration. Several experiments show that the steady state performance (i.e., many snapshots are used to calculate the array weights) of the experimental system compares favorably with its theoretical performance. It is demonstrated that standard SMI does not yield adequate suppression of weak interference. Modified SMI is then used to experimentally increase this suppression by as much as 13dB.

  11. Factors influencing dust suppressant effectiveness

    SciTech Connect

    Copeland, C.R.; Eisele, T.C.; Chesney, D.J.; Kawatra, S.K.

    2008-11-15

    Water sprays are a common method used to reduce particulate matter (PM) emissions. Various factors such as wettability, surface area coverage, fine particle engulfment rates, interparticle adhesion forces, suppressant penetration and suppressant longevity have all been suggested as critical factors in achieving effective PM control. However, it has not been established which of these factors are the most important. Experimental work indicated that suppressant penetration is the most critical of these factors. The length of time after application that suppressants were effective was also improved by using hygroscopic reagents that retained moisture to prevent evaporation. Maximizing suppressant penetration and improving suppressant longevity led to an average 86% reduction in PM10 concentrations in laboratory dust tower tests.

  12. ZERO SUPPRESSION FOR RECORDERS

    DOEpatents

    Fort, W.G.S.

    1958-12-30

    A zero-suppression circuit for self-balancing recorder instruments is presented. The essential elements of the circuit include a converter-amplifier having two inputs, one for a reference voltage and the other for the signal voltage under analysis, and a servomotor with two control windings, one coupled to the a-c output of the converter-amplifier and the other receiving a reference input. Each input circuit to the converter-amplifier has a variable potentiometer and the sliders of the potentiometer are ganged together for movement by the servoinotor. The particular noveity of the circuit resides in the selection of resistance values for the potentiometer and a resistor in series with the potentiometer of the signal circuit to ensure the full value of signal voltage variation is impressed on a recorder mechanism driven by servomotor.

  13. Pressure suppression system

    DOEpatents

    Gluntz, D.M.

    1994-10-04

    A pressure suppression system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and an enclosed gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel. The GDCS pool includes a plenum for receiving through an inlet the non-condensable gas carried with steam from the drywell following a loss-of-coolant accident (LOCA). A condenser is disposed in the GDCS plenum for condensing the steam channeled therein and to trap the non-condensable gas therein. A method of operation includes draining the GDCS pool following the LOCA and channeling steam released into the drywell following the LOCA into the GDCS plenum for cooling along with the non-condensable gas carried therewith for trapping the gas therein. 3 figs.

  14. Pressure suppression system

    DOEpatents

    Gluntz, Douglas M.

    1994-01-01

    A pressure suppression system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and an enclosed gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel. The GDCS pool includes a plenum for receiving through an inlet the non-condensable gas carried with steam from the drywell following a loss-of-coolant accident (LOCA). A condenser is disposed in the GDCS plenum for condensing the steam channeled therein and to trap the non-condensable gas therein. A method of operation includes draining the GDCS pool following the LOCA and channeling steam released into the drywell following the LOCA into the GDCS plenum for cooling along with the non-condensable gas carried therewith for trapping the gas therein.

  15. Reading Ability Is Negatively Related to Stroop Interference

    ERIC Educational Resources Information Center

    Protopapas, Athanassios; Archonti, Anastasia; Skaloumbakas, Christos

    2007-01-01

    Stroop interference is often taken as evidence for reading automaticity even though young and poor readers, who presumably lack reading automaticity, present strong interference. Here the relationship between reading skills and Stroop interference was studied in a 7th-grade sample. Greater interference was observed in children diagnosed with…

  16. 37 CFR 2.98 - Adding party to interference.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2011-07-01 2011-07-01 false Adding party to interference....98 Adding party to interference. A party may be added to an interference only upon petition to the... interference is not added, the examiner may suspend action on the application pending termination of...

  17. 37 CFR 2.98 - Adding party to interference.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2010-07-01 2010-07-01 false Adding party to interference....98 Adding party to interference. A party may be added to an interference only upon petition to the... interference is not added, the examiner may suspend action on the application pending termination of...

  18. 37 CFR 2.98 - Adding party to interference.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2014-07-01 2014-07-01 false Adding party to interference....98 Adding party to interference. A party may be added to an interference only upon petition to the... interference is not added, the examiner may suspend action on the application pending termination of...

  19. 37 CFR 2.98 - Adding party to interference.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2012-07-01 2012-07-01 false Adding party to interference....98 Adding party to interference. A party may be added to an interference only upon petition to the... interference is not added, the examiner may suspend action on the application pending termination of...

  20. 37 CFR 2.98 - Adding party to interference.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2013-07-01 2013-07-01 false Adding party to interference....98 Adding party to interference. A party may be added to an interference only upon petition to the... interference is not added, the examiner may suspend action on the application pending termination of...