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Sample records for activities avoid redundancies

  1. Obstacle avoidance for redundant robots using configuration control

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun (Inventor); Colbaugh, Richard D. (Inventor); Glass, Kristin L. (Inventor)

    1992-01-01

    A redundant robot control scheme is provided for avoiding obstacles in a workspace during the motion of an end effector along a preselected trajectory by stopping motion of the critical point on the robot closest to the obstacle when the distance between is reduced to a predetermined sphere of influence surrounding the obstacle. Algorithms are provided for conveniently determining the critical point and critical distance.

  2. Evolution of ribonuclease H genes in prokaryotes to avoid inheritance of redundant genes

    PubMed Central

    Kochiwa, Hiromi; Tomita, Masaru; Kanai, Akio

    2007-01-01

    Background A theoretical model of genetic redundancy has proposed that the fates of redundant genes depend on the degree of functional redundancy, and that functionally redundant genes will not be inherited together. However, no example of actual gene evolution has been reported that can be used to test this model. Here, we analyzed the molecular evolution of the ribonuclease H (RNase H) family in prokaryotes and used the results to examine the implications of functional redundancy for gene evolution. Results In prokaryotes, RNase H has been classified into RNase HI, HII, and HIII on the basis of amino acid sequences. Using 353 prokaryotic genomes, we identified the genes encoding the RNase H group and examined combinations of these genes in individual genomes. We found that the RNase H group may have evolved in such a way that the RNase HI and HIII genes will not coexist within a single genome – in other words, these genes are inherited in a mutually exclusive manner. Avoiding the simultaneous inheritance of the RNase HI and HIII genes is remarkable when RNase HI contains an additional non-RNase H domain, double-stranded RNA, and an RNA-DNA hybrid-binding domain, which is often observed in eukaryotic RNase H1. This evolutionary process may have resulted from functional redundancy of these genes, because the substrate preferences of RNase HI and RNase HIII are similar. Conclusion We provide two possible evolutionary models for RNase H genes in which functional redundancy contributes to the exclusion of redundant genes from the genome of a species. This is the first empirical study to show the effect of functional redundancy on changes in gene constitution during the course of evolution. PMID:17663799

  3. An obstacle avoidance method for a redundant manipulator controlled through a recurrent neural network

    NASA Astrophysics Data System (ADS)

    Arena, Paolo; Cruse, Holk; Fortuna, Luigi; Patané, Luca

    2007-05-01

    In this paper we study the problem of obstacle avoidance for a redundant manipulator. The manipulator is controlled through an already developed recurrent neural network, called MMC-model (Mean of Multiple Computation), able to solve the kinematics of manipulators in any configuration. This approach solves both problems of direct and inverse kinematics by simple numerical iterations. The MMC-model here proposed is constituted by a linear part that performs the topological analysis without any constraint and by a second layer, with nonlinear blocks used to add the constraints related to both the mechanical structure of the manipulator and the obstacles located in the operative space. The control architecture was evaluated in simulation for a planar manipulator with three links. The robot starting from a given initial configuration is able to reach a target position chosen in the operative space avoiding collisions with an obstacle placed in the plane. The obstacle is identified by simulated sensors placed on each link, they can measure the distance between link and obstacle. The reaction to the obstacle proximity can be modulated through a damping factor that improves the smoothing of the robot trajectory. The good results obtained open the way to a hardware implementation for the real-time control of a redundant manipulator.

  4. Active parallel redundancy for electronic integrator-type control circuits

    NASA Technical Reports Server (NTRS)

    Peterson, R. A.

    1971-01-01

    Circuit extends concept of redundant feedback control from type-0 to type-1 control systems. Inactive channels are slaves to the active channel, if latter fails, it is rejected and slave channel is activated. High reliability and elimination of single-component catastrophic failure are important in closed-loop control systems.

  5. Dynamic active constraints for hyper-redundant flexible robots.

    PubMed

    Kwok, Ka-Wai; Mylonas, George P; Sun, Loi Wah; Lerotic, Mirna; Clark, James; Athanasiou, Thanos; Darzi, Ara; Yang, Guang-Zhong

    2009-01-01

    In robot-assisted procedures, the surgeon's ability can be enhanced by navigation guidance through the use of virtual fixtures or active constraints. This paper presents a real-time modeling scheme for dynamic active constraints with fast and simple mesh adaptation under cardiac deformation and changes in anatomic structure. A smooth tubular pathway is constructed which provides assistance for a flexible hyper-redundant robot to circumnavigate the heart with the aim of undertaking bilateral pulmonary vein isolation as part of a modified maze procedure for the treatment of debilitating arrhythmia and atrial fibrillation. In contrast to existing approaches, the method incorporates detailed geometrical constraints with explicit manipulation margins of the forbidden region for an entire articulated surgical instrument, rather than just the end-effector itself. Detailed experimental validation is conducted to demonstrate the speed and accuracy of the instrument navigation with and without the use of the proposed dynamic constraints.

  6. Active Collision Avoidance for Planetary Landers

    NASA Technical Reports Server (NTRS)

    Rickman, Doug; Hannan, Mike; Srinivasan, Karthik

    2014-01-01

    Present day robotic missions to other planets require precise, a priori knowledge of the terrain to pre-determine a landing spot that is safe. Landing sites can be miles from the mission objective, or, mission objectives may be tailored to suit landing sites. Future robotic exploration missions should be capable of autonomously identifying a safe landing target within a specified target area selected by mission requirements. Such autonomous landing sites must (1) 'see' the surface, (2) identify a target, and (3) land the vehicle. Recent advances in radar technology have resulted in small, lightweight, low power radars that are used for collision avoidance and cruise control systems in automobiles. Such radar systems can be adapted for use as active hazard avoidance systems for planetary landers. The focus of this CIF proposal is to leverage earlier work on collision avoidance systems for MSFC's Mighty Eagle lander and evaluate the use of automotive radar systems for collision avoidance in planetary landers.

  7. Design and evaluation of an electrohydraulic servoactuator using active standby redundancy

    NASA Technical Reports Server (NTRS)

    Anderson, R. L.; Cover, W. E.

    1972-01-01

    The application is described of active standby redundancy techniques to a large electrohydraulic servoactuator. The advantages and limitations of active standby redundancy are identified. Special areas of investigation during the development test phase of the program were the evaluation of output transients as a function of channel switching and the nuisance switching characteristics of the system. The feasibility of constructing large electrohydraulic servoactuators using active standby redundancy was successfully demonstrated. In particular the stability and predictability of a properly designed hydromechanical failure detector was demonstrated.

  8. Redundant kinase activation and resistance of EGFR-tyrosine kinase inhibitors

    PubMed Central

    Luo, Min; Fu, Li-Wu

    2014-01-01

    Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have shown dramatic effects against that tumors harboring EGFR activating mutations in the EGFR intracytoplasmic tyrosine kinase domain and resulted in cell apoptosis. Unfortunately, a number of patients ultimately developed resistance by multiple mechanisms. Thus, elucidation of the mechanism of resistance to EGFR-TKIs can provide strategies for blocking or reversing the situation. Recent studies suggested that redundant kinase activation plays pivotal roles in escaping from the effects of EGFR-TKIs. Herein, we aimed to characterize several molecular events involved in the resistance to EGFR-TKIs mediated by redundant kinase activation. PMID:25520855

  9. Assessment of the Minimum Sampling Frequency to Avoid Measurement Redundancy in Microclimate Field Surveys in Museum Buildings.

    PubMed

    García-Diego, Fernando-Juan; Verticchio, Elena; Beltrán, Pedro; Siani, Anna Maria

    2016-01-01

    Monitoring temperature and relative humidity of the environment to which artefacts are exposed is fundamental in preventive conservation studies. The common approach in setting measuring instruments is the choice of a high sampling rate to detect short fluctuations and increase the accuracy of statistical analysis. However, in recent cultural heritage standards the evaluation of variability is based on moving average and short fluctuations and therefore massive acquisition of data in slowly-changing indoor environments could end up being redundant. In this research, the sampling frequency to set a datalogger in a museum room and inside a microclimate frame is investigated by comparing the outcomes obtained from datasheets associated with different sampling conditions. Thermo-hygrometric data collected in the Sorolla room of the Pio V Museum of Valencia (Spain) were used and the widely consulted recommendations issued in UNI 10829:1999 and EN 15757:2010 standards and in the American Society of Heating, Air-Conditioning and Refrigerating Engineers (ASHRAE) guidelines were applied. Hourly sampling proved effective in obtaining highly reliable results. Furthermore, it was found that in some instances daily means of data sampled every hour can lead to the same conclusions as those of high frequency. This allows us to improve data logging design and manageability of the resulting datasheets. PMID:27537886

  10. Assessment of the Minimum Sampling Frequency to Avoid Measurement Redundancy in Microclimate Field Surveys in Museum Buildings

    PubMed Central

    García-Diego, Fernando-Juan; Verticchio, Elena; Beltrán, Pedro; Siani, Anna Maria

    2016-01-01

    Monitoring temperature and relative humidity of the environment to which artefacts are exposed is fundamental in preventive conservation studies. The common approach in setting measuring instruments is the choice of a high sampling rate to detect short fluctuations and increase the accuracy of statistical analysis. However, in recent cultural heritage standards the evaluation of variability is based on moving average and short fluctuations and therefore massive acquisition of data in slowly-changing indoor environments could end up being redundant. In this research, the sampling frequency to set a datalogger in a museum room and inside a microclimate frame is investigated by comparing the outcomes obtained from datasheets associated with different sampling conditions. Thermo-hygrometric data collected in the Sorolla room of the Pio V Museum of Valencia (Spain) were used and the widely consulted recommendations issued in UNI 10829:1999 and EN 15757:2010 standards and in the American Society of Heating, Air-Conditioning and Refrigerating Engineers (ASHRAE) guidelines were applied. Hourly sampling proved effective in obtaining highly reliable results. Furthermore, it was found that in some instances daily means of data sampled every hour can lead to the same conclusions as those of high frequency. This allows us to improve data logging design and manageability of the resulting datasheets. PMID:27537886

  11. Production-on-the-Go Practice: Storyboarding as a Retrospective and Redundant School Literacy Activity

    ERIC Educational Resources Information Center

    Tan, Lynde

    2013-01-01

    Storyboarding is one common strategy used in teaching young people digital media. This paper argues that in adolescents' literacy practices, they engage in production on the go. The metaphor is described in this paper to put forward the argument that storyboarding can be a retrospective and redundant literacy activity in adolescents'…

  12. Neural correlates of active avoidance behavior in superior colliculus

    PubMed Central

    Cohen, Jeremy D.; Castro-Alamancos, Manuel A.

    2010-01-01

    Active avoidance of harmful situations seems highly adaptive, but the underlying neural mechanisms are largely unknown. Rats can effectively use the superior colliculus during active avoidance to detect a salient whisker conditioned stimulus (WCS) that signals an aversive event. Here, we recorded unit and field potential activity in the intermediate layers of the superior colliculus of rats during active avoidance behavior. During the period preceding the onset of the WCS, avoids are associated with a higher firing rate than escapes (unsuccessful avoids), indicating that a prepared superior colliculus is more likely to detect the WCS and lead to an avoid. Moreover, during the WCS, a robust ramping up of overall firing rate is observed for trials leading to avoids. The firing rate ramping is not due to shuttling, and may serve to drive downstream circuits to avoid. Therefore, a robust neural correlate of active avoidance behavior is found in the superior colliculus, emphasizing its role in the detection of salient sensory signals that require immediate action. PMID:20573897

  13. Two enzymes with redundant fructose bisphosphatase activity sustain gluconeogenesis and virulence in Mycobacterium tuberculosis

    PubMed Central

    Ganapathy, Uday; Marrero, Joeli; Calhoun, Susannah; Eoh, Hyungjin; de Carvalho, Luiz Pedro Sorio; Rhee, Kyu; Ehrt, Sabine

    2015-01-01

    The human pathogen Mycobacterium tuberculosis (Mtb) likely utilizes host fatty acids as a carbon source during infection. Gluconeogenesis is essential for the conversion of fatty acids into biomass. A rate-limiting step in gluconeogenesis is the conversion of fructose 1,6-bisphosphate to fructose 6-phosphate by a fructose bisphosphatase (FBPase). The Mtb genome contains only one annotated FBPase gene, glpX. Here we show that, unexpectedly, an Mtb mutant lacking GLPX grows on gluconeogenic carbon sources and has detectable FBPase activity. We demonstrate that the Mtb genome encodes an alternative FBPase (GPM2, Rv3214) that can maintain gluconeogenesis in the absence of GLPX. Consequently, deletion of both GLPX and GPM2 is required for disruption of gluconeogenesis and attenuation of Mtb in a mouse model of infection. Our work affirms a role for gluconeogenesis in Mtb virulence and reveals previously unidentified metabolic redundancy at the FBPase-catalysed reaction step of the pathway. PMID:26258286

  14. Nucleus accumbens core lesions enhance two-way active avoidance

    PubMed Central

    Lichtenberg, Nina T.; Kashtelyan, Vadim; Burton, Amanda C.; Bissonette, Gregory B.; Roesch, Matthew R.

    2014-01-01

    The majority of work examining nucleus accumbens core (NAc) has focused on functions pertaining to behaviors guided by appetitive outcomes. These studies have pointed to NAc as being critical for motivating behavior toward desirable outcomes. For example, we have recently shown that lesions of NAc impaired performance on a reward-guided decision-making task that required rats to choose between differently valued rewards. Unfortunately, much less is known about the role that NAc plays in motivating behavior when aversive outcomes are predicted. To address this issue we asked if NAc lesions impact performance on a two-way active avoidance task in which rats must learn to shuttle back and forth in a behavioral training box in order to avoid a footshock predicted by an auditory tone. Although bilateral NAc lesions initially impaired reward-guided decision-making, we found that the same lesions improved acquisition and retention of two-way active avoidance. PMID:24275320

  15. Phospholipase C Epsilon (PLCε) Induced TRPC6 Activation: A Common but Redundant Mechanism in Primary Podocytes

    PubMed Central

    Kalwa, Hermann; Storch, Ursula; Demleitner, Jana; Fiedler, Susanne; Mayer, Tim; Kannler, Martina; Fahlbusch, Meike; Barth, Holger; Smrcka, Alan; Hildebrandt, Friedhelm; Gudermann, Thomas; Dietrich, Alexander

    2016-01-01

    In eukaryotic cells, activation of phospholipase C (PLC)-coupled membrane receptors by hormones leads to an increase in the intracellular Ca2+ concentration [Ca2+]i. Catalytic activity of PLCs results in the hydrolysis of phosphatidylinositol 4,5-bisphosphate to generate inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG) which opens DAG-sensitive classical transient receptor channels 3, 6, and 7 (TRPC3/6/7), initiating Ca2+ influx from the extracellular space. Patients with focal segmental glomerulosclerosis (FSGS) express gain-of-function mutants of TRPC6, while others carry loss-of-function mutants of PLCε, raising the intriguing possibility that both proteins interact and might work in the same signalling pathway. While TRPC6 activation by PLCβ and PLCγ isozymes was extensively studied, the role of PLCε in TRPC6 activation remains elusive. TRPC6 was co-immunoprecipitated with PLCε in a heterologous overexpression system in HEK293 cells as well as in freshly isolated murine podocytes. Receptor-operated TRPC6 currents in HEK293 cells expressing TRPC6 were reduced by a specific PLCε siRNA and by a PLCε loss-of-function mutant isolated from a patient with FSGS. PLCε-induced TRPC6 activation was also identified in murine embryonic fibroblasts (MEFs) lacking Gαq/11 proteins. Further analysis of the signal transduction pathway revealed a Gα12/13 Rho-GEF activation which induced Rho-mediated PLCε stimulation. Therefore, we identified a new pathway for TRPC6 activation by PLCε. PLCε-/- podocytes however, were undistinguishable from WT podocytes in their angiotensin II-induced formation of actin stress fibers and their GTPγS-induced TRPC6 activation, pointing to a redundant role of PLCε-mediated TRPC6 activation at least in podocytes. PMID:25521631

  16. Identification of seven hydrophobic clusters in GCN4 making redundant contributions to transcriptional activation.

    PubMed Central

    Jackson, B M; Drysdale, C M; Natarajan, K; Hinnebusch, A G

    1996-01-01

    GCN4 is a transcriptional activator in the bZIP family that regulates amino acid biosynthetic genes in the yeast Saccharomyces cerevisiae. The N-terminal 100 amino acids of GCN4 contains a potent activation function that confers high-level transcription in the absence of the centrally located acidic activation domain (CAAD) delineated in previous studies. To identify specific amino acids important for activation by the N-terminal domain, we mutagenized a GCN4 allele lacking the CAAD and screened alleles in vivo for reduced expression of the HIS3 gene. We found four pairs of closely spaced phenylalanines and a leucine residue distributed throughout the N-terminal 100 residues of GCN4 that are required for high-level activation in the absence of the CAAD. Trp, Leu, and Tyr were highly functional substitutions for the Phe residue at position 45. Combined with our previous findings, these results indicate that GCN4 contains seven clusters of aromatic or bulky hydrophobic residues which make important contributions to transcriptional activation at HIS3. None of the seven hydrophobic clusters is essential for activation by full-length GCN4, and the critical residues in two or three clusters must be mutated simultaneously to observe a substantial reduction in GCN4 function. Numerous combinations of four or five intact clusters conferred high-level transcription of HIS3. We propose that many of the hydrophobic clusters in GCN4 act independently of one another to provide redundant means of stimulating transcription and that the functional contributions of these different segments are cumulative at the HIS3 promoter. On the basis of the primacy of bulky hydrophobic residues throughout the activation domain, we suggest that GCN4 contains multiple sites that mediate hydrophobic contacts with one or more components of the transcription initiation machinery. PMID:8816468

  17. Ethernet redundancy

    SciTech Connect

    Burak, K.

    2006-07-01

    We describe the Ethernet systems and their evolution: LAN Segmentation, DUAL networks, network loops, network redundancy and redundant network access. Ethernet (IEEE 802.3) is an open standard with no licensing fees and its specifications are freely available. As a result, it is the most popular data link protocol in use. It is important that the network be redundant and standard Ethernet protocols like RSTP (IEEE 802.1w) provide the fast network fault detection and recovery times that is required today. As Ethernet does continue to evolve, network redundancy is and will be a mixture of technology standards. So it is very important that both end-stations and networking devices be Ethernet (IEEE 802.3) compliant. Then when new technologies, such as the IEEE 802.1aq Shortest Path Bridging protocol, come to market they can be easily deployed in the network without worry.

  18. Ara h 2 and Ara h 6 have similar allergenic activity1 and are substantially redundant

    PubMed Central

    Chen, Xueni; Wang, Qian; El-Mezayen, Rabab; Zhuang, Yonghua; Dreskin, Stephen. C.

    2013-01-01

    Background The moderately homologous (~60%) proteins, Ara h 2 and Ara h 6, are the most potent peanut allergens. This study was designed to define the relative individual contributions of Ara h 2 and Ara h 6 to the overall allergenic activity of a crude peanut extract (CPE). Methods Ara h 2 and Ara h 6 were removed from CPE by gel filtration chromatography. Ara h 2.01, Ara h 2.02, and Ara h 6 were further purified (>99%). The potency of each allergen and the ability of these allergens to reconstitute the allergenic activity of CPE depleted of Ara h 2 and Ara h 6 was measured with RBL SX-38 cells sensitized with IgE from sensitized peanut allergic patients. Results The potency of the native proteins were significantly different (p<0.0001) although not dramatically so, with a rank order of Ara h 2.01 > Ara h 2.02 > Ara h 6. The addition of either purified Ara h 2 or Ara h 6 independently at their original concentration to CPE depleted of both Ara h 2 and Ara h 6 restored 80–100% of the original CPE allergenic activity. Addition of both Ara h 2 and Ara h 6 consistently completely restored the allergenic activity of CPE. Conclusions These studies indicate that either Ara h 2 or Ara h 6 independently can account for most of the allergenic activity in a CPE and demonstrate important redundancy in the allergenic activity of these related molecules. PMID:23075924

  19. Disruption avoidance through active magnetic feedback in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Paccagnella, Roberto; Zanca, Paolo; Yanovskiy, Vadim; Finotti, Claudio; Manduchi, Gabriele; Piron, Chiara; Carraro, Lorella; Franz, Paolo; RFX Team

    2014-10-01

    Disruptions avoidance and mitigation is a fundamental need for a fusion relevant tokamak. In this paper a new experimental approach for disruption avoidance using active magnetic feedback is presented. This scheme has been implemented and tested on the RFX-mod device operating as a circular tokamak. RFX-mod has a very complete system designed for active mode control that has been proved successful for the stabilization of the Resistive Wall Modes (RWMs). In particular the current driven 2/1 mode, unstable when the edge safety factor, qa, is around (or even less than) 2, has been shown to be fully and robustly stabilized. However, at values of qa (qa > 3), the control of the tearing 2/1 mode has been proved difficult. These results suggested the idea to prevent disruptions by suddenly lowering qa to values around 2 where the tearing 2/1 is converted to a RWM. Contrary to the universally accepted idea that the tokamaks should disrupt at low qa, we demonstrate that in presence of a well designed active control system, tokamak plasmas can be driven to low qa actively stabilized states avoiding plasma disruption with practically no loss of the plasma internal energy.

  20. Minimum-Time and Vibration Avoidance Attitude Maneuver for Spacecraft with Torque and Momentum Limit Constraints in Redundant Reaction Wheel Configuration

    NASA Technical Reports Server (NTRS)

    Ha, Kong Q.; Femiano, Michael D.; Mosier, Gary E.

    2004-01-01

    This viewgraph presentation presents an algorithm for trajectory control of a spacecraft that minimizes the time to perform slews, including settling, by avoiding reaction wheel torque and momentum limits that would excite flexible structural modes. This algorithm was validated by simulation during the design of the NGST 'Yardstick' (precursor to JWST). Performance verification of a reduced form for single-axis slews was carried out using the MIT Origins Testbed. It is currently baselined for use by TPF-Coronagraph.

  1. Minimum-Time and Vibration Avoidance Attitude Maneuver for Spacecraft with Torque and Momentum Limit Constraints in Redundant Reaction Wheel Configuration

    NASA Technical Reports Server (NTRS)

    Ha, Kong Q.; Femiano, Michael D.; Mosier, Gary E.

    2004-01-01

    In this paper, we present an optimal open-loop slew trajectory algorithm developed at GSFC for the so-called "Yardstick design" of the James Webb Space Telescope (JWST). JWST is an orbiting infrared observatory featuring a lightweight, segmented primary mirror approximately 6 meters in diameter and a sunshield approximately the size of a tennis court. This large, flexible structure will have significant number of lightly damped, dominant flexible modes. With very stringent requirements on pointing accuracy and image quality, it is important that slewing be done within the required time constraint and with minimal induced vibration in order to maximize observing efficiency. With reaction wheels as control actuators, initial wheel speeds as well as individual wheel torque and momentum limits become dominant constraints in slew performance. These constraints must be taken into account when performing slews to ensure that unexpected reaction wheel saturation does not occur, since such saturation leads to control failure in accurately tracking commanded motion and produces high frequency torque components capable of exciting structural modes. A minimum-time constraint is also included and coupled with reaction wheel limit constraints in the optimization to minimize both the effect of the control torque on the flexible body motion and the maneuver time. The optimization is on slew command parameters, such as maximum slew velocity and acceleration, for a given redundant reaction wheel configuration and is based on the dynamic interaction between the spacecraft and reaction wheel motion. Analytical development of the slew algorithm to generate desired slew position, rate, and acceleration profiles to command a feedback/feed forward control system is described. High-fidelity simulation and experimental results are presented to show that the developed slew law achieves the objectives.

  2. Kinematically redundant robot manipulators

    NASA Technical Reports Server (NTRS)

    Baillieul, J.; Hollerbach, J.; Brockett, R.; Martin, D.; Percy, R.; Thomas, R.

    1987-01-01

    Research on control, design and programming of kinematically redundant robot manipulators (KRRM) is discussed. These are devices in which there are more joint space degrees of freedom than are required to achieve every position and orientation of the end-effector necessary for a given task in a given workspace. The technological developments described here deal with: kinematic programming techniques for automatically generating joint-space trajectories to execute prescribed tasks; control of redundant manipulators to optimize dynamic criteria (e.g., applications of forces and moments at the end-effector that optimally distribute the loading of actuators); and design of KRRMs to optimize functionality in congested work environments or to achieve other goals unattainable with non-redundant manipulators. Kinematic programming techniques are discussed, which show that some pseudo-inverse techniques that have been proposed for redundant manipulator control fail to achieve the goals of avoiding kinematic singularities and also generating closed joint-space paths corresponding to close paths of the end effector in the workspace. The extended Jacobian is proposed as an alternative to pseudo-inverse techniques.

  3. Redundant disc

    NASA Technical Reports Server (NTRS)

    Barack, W. N.; Domas, P. A.; Beekman, S. W. (Inventor)

    1978-01-01

    A rotatable disc is described that consists of parallel plates tightly joined together for rotation about a hub. Each plate is provided with several angularly projecting spaced lands. The lands of each plate are interposed in alternating relationship between the lands of the next adjacent plate. In this manner, circumferential displacement of adjacent sectors in any one plate is prevented in the event that a crack develops. Each plate is redundantly sized so that, in event of structural failure of one plate, the remaining plates support a proportionate share of the load of the failed plate. The plates are prevented from separating laterally through the inclusion of generally radially extending splines which are inserted to interlock cooperating, circumferentially adjacent lands.

  4. Radiation and Dual Checkpoint Blockade Activates Non-Redundant Immune Mechanisms in Cancer

    PubMed Central

    Victor, Christina Twyman-Saint; Rech, Andrew J.; Maity, Amit; Rengan, Ramesh; Pauken, Kristen E.; Stelekati, Erietta; Benci, Joseph L.; Xu, Bihui; Dada, Hannah; Odorizzi, Pamela M.; Herati, Ramin S.; Mansfield, Kathleen D.; Patsch, Dana; Amaravadi, Ravi K.; Schuchter, Lynn M.; Ishwaran, Hemant; Mick, Rosemarie; Pryma, Daniel A.; Xu, Xiaowei; Feldman, Michael D.; Gangadhar, Tara C.; Hahn, Stephen M.; Wherry, E. John; Vonderheide, Robert H.; Minn, Andy J.

    2015-01-01

    Immune checkpoint inhibitors1 result in impressive clinical responses2–5 but optimal results will require combination with each other6 and other therapies. This raises fundamental questions about mechanisms of non-redundancy and resistance. Here, we report major tumor regressions in a subset of patients with metastatic melanoma treated with an anti-CTLA4 antibody (anti-CTLA4) and radiation (RT) and reproduced this effect in mouse models. Although combined treatment improved responses in irradiated and unirradiated tumors, resistance was common. Unbiased analyses of mice revealed that resistance was due to upregulation of PD-L1 on melanoma cells and associated with T cell exhaustion. Accordingly, optimal response in melanoma and other cancer types requires RT, anti-CTLA4, and anti-PD-L1/PD-1. Anti-CTLA4 predominantly inhibits T regulatory cells (Tregs) to increase the CD8 T cell to Treg (CD8/Treg) ratio. RT enhances the diversity of the T cell receptor (TCR) repertoire of intratumoral T cells. Together, anti-CTLA4 promotes expansion of T cells, while RT shapes the TCR repertoire of the expanded peripheral clones. Addition of PD-L1 blockade reverses T cell exhaustion to mitigate depression in the CD8/Treg ratio and further encourages oligo-clonal T cell expansion. Similar to results from mice, patients on our clinical trial with melanoma showing high PD-L1 did not respond to RT + anti-CTLA4, demonstrated persistent T cell exhaustion, and rapidly progressed. Thus, PD-L1 on melanoma cells allows tumors to escape anti-CTLA4-based therapy, and the combination of RT, anti-CTLA4, and anti-PD-L1 promotes response and immunity through distinct mechanisms. PMID:25754329

  5. Hierarchical Brain Networks Active in Approach and Avoidance Goal Pursuit

    PubMed Central

    Spielberg, Jeffrey M.; Heller, Wendy; Miller, Gregory A.

    2013-01-01

    Effective approach/avoidance goal pursuit is critical for attaining long-term health and well-being. Research on the neural correlates of key goal-pursuit processes (e.g., motivation) has long been of interest, with lateralization in prefrontal cortex being a particularly fruitful target of investigation. However, this literature has often been limited by a lack of spatial specificity and has not delineated the precise aspects of approach/avoidance motivation involved. Additionally, the relationships among brain regions (i.e., network connectivity) vital to goal-pursuit remain largely unexplored. Specificity in location, process, and network relationship is vital for moving beyond gross characterizations of function and identifying the precise cortical mechanisms involved in motivation. The present paper integrates research using more spatially specific methodologies (e.g., functional magnetic resonance imaging) with the rich psychological literature on approach/avoidance to propose an integrative network model that takes advantage of the strengths of each of these literatures. PMID:23785328

  6. How to Make an Active Zone: Unexpected Universal Functional Redundancy between RIMs and RIM-BPs.

    PubMed

    Acuna, Claudio; Liu, Xinran; Südhof, Thomas C

    2016-08-17

    RIMs and RIM-binding proteins (RBPs) are evolutionary conserved multidomain proteins of presynaptic active zones that are known to recruit Ca(2+) channels; in addition, RIMs perform well-recognized functions in tethering and priming synaptic vesicles for exocytosis. However, deletions of RIMs or RBPs in mice cause only partial impairments in various active zone functions and have no effect on active zone structure, as visualized by electron micrographs, suggesting that their contribution to active zone functions is limited. Here, we show in synapses of the calyx of Held in vivo and hippocampal neurons in culture that combined, but not individual, deletions of RIMs and RBPs eliminate tethering and priming of synaptic vesicles, deplete presynaptic Ca(2+) channels, and ablate active zone complexes, as analyzed by electron microscopy of chemically fixed synapses. Thus, RBPs perform unexpectedly broad roles at the active zone that together with those of RIMs are essential for all active zone functions. PMID:27537484

  7. How to Make an Active Zone: Unexpected Universal Functional Redundancy between RIMs and RIM-BPs.

    PubMed

    Acuna, Claudio; Liu, Xinran; Südhof, Thomas C

    2016-08-17

    RIMs and RIM-binding proteins (RBPs) are evolutionary conserved multidomain proteins of presynaptic active zones that are known to recruit Ca(2+) channels; in addition, RIMs perform well-recognized functions in tethering and priming synaptic vesicles for exocytosis. However, deletions of RIMs or RBPs in mice cause only partial impairments in various active zone functions and have no effect on active zone structure, as visualized by electron micrographs, suggesting that their contribution to active zone functions is limited. Here, we show in synapses of the calyx of Held in vivo and hippocampal neurons in culture that combined, but not individual, deletions of RIMs and RBPs eliminate tethering and priming of synaptic vesicles, deplete presynaptic Ca(2+) channels, and ablate active zone complexes, as analyzed by electron microscopy of chemically fixed synapses. Thus, RBPs perform unexpectedly broad roles at the active zone that together with those of RIMs are essential for all active zone functions.

  8. Active core rewarming avoids bioelectrical impedance changes in postanesthetic patients

    PubMed Central

    2011-01-01

    Background Postoperative hypothermia is a common cause of complications in patients who underwent laparoscopic cholecystectomy. Hypothermia is known to elicit electrophysiological, biochemical, and cellular alterations thus leading to changes in the active and passive membrane properties. These changes might influence the bioelectrical impedance (BI). Our aim was to determine whether the BI depends on the core temperature. Methods We studied 60 patients (52 female and 8 male) age 40 to 80 years with an ASA I-II classification that had undergone laparoscopic cholecystectomy under balanced inhalation anesthesia. The experimental group (n = 30) received active core rewarming during the transanesthetic and postanesthesic periods. The control group (n = 30) received passive external rewarming. The BI was recorded by using a 4-contact electrode system to collect dual sets of measurements in the deltoid muscle. The body temperature, hemodynamic variables, respiratory rate, blood-gas levels, biochemical parameters, and shivering were also measured. The Mann-Whitney unpaired t-test was used to determine the differences in shivering between each group at each measurement period. Measurements of body temperature, hemodynamics variables, respiratory rate, and BI were analyzed using the two-way repeated-measures ANOVA. Results The gradual decrease in the body temperature was followed by the BI increase over time. The highest BI values (95 ± 11 Ω) appeared when the lowest values of the temperature (35.5 ± 0.5°C) were reached. The active core rewarming kept the body temperature within the physiological range (over 36.5°C). This effect was accompanied by low stable values (68 ± 3 Ω) of BI. A significant decrease over time in the hemodynamic values, respiratory rate, and shivering was seen in the active core-rewarming group when compared with the controls. The temporal course of shivering was different from those of body temperatue and BI. The control patients showed a

  9. Graduated Exposure and Positive Reinforcement to Overcome Setting and Activity Avoidance in an Adolescent with Autism

    ERIC Educational Resources Information Center

    Schmidt, Jonathan D.; Luiselli, James K.; Rue, Hanna; Whalley, Katherine

    2013-01-01

    Some students who have developmental disabilities avoid settings and activities that can improve their learning and quality of life. This two-phase study concerned an adolescent boy with autism who avoided the gross-motor exercise room, gymnasium, and music room at his school; he demonstrated distress, agitation, and problem behaviors when…

  10. Antecedents of Approach-Avoidance Achievement Goal Adoption: An Analysis of Two Physical Education Activities

    ERIC Educational Resources Information Center

    Warburton, Victoria; Spray, Christopher

    2013-01-01

    The purpose of this study was to determine the relationship between implicit theories of ability and competence perceptions to changes in approach-avoidance goal adoption in two specific activities in the curriculum. Four hundred and thirty pupils, aged 11-15 years, completed measures of approach-avoidance goals, perceived competence and implicit…

  11. Individual differences in sensitivity to reward and punishment and neural activity during reward and avoidance learning.

    PubMed

    Kim, Sang Hee; Yoon, HeungSik; Kim, Hackjin; Hamann, Stephan

    2015-09-01

    In this functional neuroimaging study, we investigated neural activations during the process of learning to gain monetary rewards and to avoid monetary loss, and how these activations are modulated by individual differences in reward and punishment sensitivity. Healthy young volunteers performed a reinforcement learning task where they chose one of two fractal stimuli associated with monetary gain (reward trials) or avoidance of monetary loss (avoidance trials). Trait sensitivity to reward and punishment was assessed using the behavioral inhibition/activation scales (BIS/BAS). Functional neuroimaging results showed activation of the striatum during the anticipation and reception periods of reward trials. During avoidance trials, activation of the dorsal striatum and prefrontal regions was found. As expected, individual differences in reward sensitivity were positively associated with activation in the left and right ventral striatum during reward reception. Individual differences in sensitivity to punishment were negatively associated with activation in the left dorsal striatum during avoidance anticipation and also with activation in the right lateral orbitofrontal cortex during receiving monetary loss. These results suggest that learning to attain reward and learning to avoid loss are dependent on separable sets of neural regions whose activity is modulated by trait sensitivity to reward or punishment.

  12. Redundant Asynchronous Microprocessor System

    NASA Technical Reports Server (NTRS)

    Meyer, G.; Johnston, J. O.; Dunn, W. R.

    1985-01-01

    Fault-tolerant computer structure called RAMPS (for redundant asynchronous microprocessor system) has simplicity of static redundancy but offers intermittent-fault handling ability of complex, dynamically redundant systems. New structure useful wherever several microprocessors are employed for control - in aircraft, industrial processes, robotics, and automatic machining, for example.

  13. Anxiety, not anger, induces inflammatory activity: An avoidance/approach model of immune system activation.

    PubMed

    Moons, Wesley G; Shields, Grant S

    2015-08-01

    Psychological stressors reliably trigger systemic inflammatory activity as indexed by levels of proinflammatory cytokines. This experiment demonstrates that one's specific emotional reaction to a stressor may be a significant determinant of whether an inflammatory reaction occurs in response to that stressor. Based on extant correlational evidence and theory, a causal approach was used to determine whether an avoidant emotion (anxiety) triggers more inflammatory activity than an approach emotion (anger). In an experimental design (N = 40), a 3-way Emotion Condition × Time × Analyte interaction revealed that a writing-based anxiety induction, but not a writing-based anger induction, increased mean levels of interferon-γ (IFN- γ) and interleukin-1β (IL-1β), but not interleukin-6 (IL-6) in oral mucous, F(2, 54) = 4.64, p = .01, ηp(²) = .15. Further, self-reported state anxiety predicted elevated levels of proinflammatory cytokines, all ΔR(²) >.06, ps <.04, but self-reported state anger did not. These results constitute the first evidence to our knowledge that specific negative emotions can differentially cause inflammatory activity and support a theoretical model explaining these effects based on the avoidance or approach motivations associated with emotions. PMID:26053247

  14. Anxiety, not anger, induces inflammatory activity: An avoidance/approach model of immune system activation.

    PubMed

    Moons, Wesley G; Shields, Grant S

    2015-08-01

    Psychological stressors reliably trigger systemic inflammatory activity as indexed by levels of proinflammatory cytokines. This experiment demonstrates that one's specific emotional reaction to a stressor may be a significant determinant of whether an inflammatory reaction occurs in response to that stressor. Based on extant correlational evidence and theory, a causal approach was used to determine whether an avoidant emotion (anxiety) triggers more inflammatory activity than an approach emotion (anger). In an experimental design (N = 40), a 3-way Emotion Condition × Time × Analyte interaction revealed that a writing-based anxiety induction, but not a writing-based anger induction, increased mean levels of interferon-γ (IFN- γ) and interleukin-1β (IL-1β), but not interleukin-6 (IL-6) in oral mucous, F(2, 54) = 4.64, p = .01, ηp(²) = .15. Further, self-reported state anxiety predicted elevated levels of proinflammatory cytokines, all ΔR(²) >.06, ps <.04, but self-reported state anger did not. These results constitute the first evidence to our knowledge that specific negative emotions can differentially cause inflammatory activity and support a theoretical model explaining these effects based on the avoidance or approach motivations associated with emotions.

  15. Graduated exposure and positive reinforcement to overcome setting and activity avoidance in an adolescent with autism.

    PubMed

    Schmidt, Jonathan D; Luiselli, James K; Rue, Hanna; Whalley, Katherine

    2013-01-01

    Some students who have developmental disabilities avoid settings and activities that can improve their learning and quality of life. This two-phase study concerned an adolescent boy with autism who avoided the gross-motor exercise room, gymnasium, and music room at his school; he demonstrated distress, agitation, and problem behaviors when prompted to enter these areas. Using graduated exposure combined with positive reinforcement, he learned to enter these settings without resisting and eventually to participate in activities within the settings. This article discusses this intervention approach for reducing and eliminating avoidant behavior.

  16. A Modular Approach to Redundant Robot Control

    SciTech Connect

    Anderson, R.J.

    1997-12-01

    This paper describes a modular approach for computing redundant robot kinematics. First some conventional redundant control methods are presented and shown to be `passive control laws`, i.e. they can be represented by a network consisting of passive elements. These networks are then put into modular form by applying scattering operator techniques. Additional subnetwork modules can then be added to further shape the motion. Modules for obstacle detection, joint limit avoidance, proximity sensing, and for imposing nonlinear velocity constraints are presented. The resulting redundant robot control system is modular, flexible and robust.

  17. Context-dependent activation of reduced autobiographical memory specificity as an avoidant coping style.

    PubMed

    Debeer, Elise; Raes, Filip; Williams, J Mark G; Hermans, Dirk

    2011-12-01

    According to the affect-regulation hypothesis (Williams et al., 2007), reduced autobiographical memory specificity (rAMS) or overgeneral memory (OGM) might be considered a cognitive avoidance strategy; that is, people learn to avoid the emotionally painful consequences associated with the retrieval of specific negative memories. Based on this hypothesis, one would predict significant negative associations between AMS and avoidant coping. However, studies investigating this prediction have led to equivocal results. In the present study we tested a possible explanation for these contradictory findings. It was hypothesized that rAMS (in part) reflects an avoidant coping strategy, which might only become apparent under certain conditions, that is, conditions that signal the possibility of 'danger.' To test this hypothesis, we assessed AMS and behavioral avoidance but experimentally manipulated the instructions. In the neutral condition, two parallel versions of the Autobiographical Memory Test (AMT) were presented under neutral instructions. In the threat condition, the first AMT was presented under neutral instructions, while the second AMT was presented under 'threat instructions.' Results showed no significant correlations between avoidance and OGM under neutral conditions but significant and markedly stronger correlations under threat conditions, with more avoidance being associated with fewer specific and more categoric memories. In addition, high avoiders showed a stronger reduction in AMS in the threat condition as compared with the neutral condition, while low avoiders showed no such difference between conditions. The data confirm that OGM can be considered as part of a broader avoidant coping style. However, more importantly, they show that, at least in nonclinical individuals, the activation of this coping style may depend on the context.

  18. Vulnerability factors in anxiety determined through differences in active-avoidance behavior.

    PubMed

    Beck, Kevin D; Jiao, Xilu; Pang, Kevin C H; Servatius, Richard J

    2010-08-16

    The risk for developing anxiety disorders is greater in females and those individuals exhibiting a behaviorally inhibited temperament. Growth of behavioral avoidance in people is a significant predictor of symptom severity in anxiety disorders, including post-traumatic stress disorder. Using an animal model, our lab is examining how the process of learning avoidant behavior may lead certain individuals to develop anxiety. Here we examined whether the known vulnerabilities of female sex and behaviorally inhibited temperament have individual or additive effects upon the acquisition of an active-avoidance response. A discrete trial lever-press escape-avoidance protocol was used to examine the acquisition of behavioral avoidance in male and female Sprague-Dawley (SD) rats and behaviorally inhibited inbred Wistar-Kyoto (WKY) rats. Overall, WKY rats of both sexes were indistinguishable in their behavior during the acquisition of an active-avoidance response, exhibiting quicker acquisition of reinforced responses both between and within session compared to SD rats. Further WKY rats emitted more non-reinforced responses than SD rats. Sex differences were evident in SD rats in both the acquisition of the reinforced response and the emission of non-reinforced responses, with SD females acquiring the response quicker and emitting more non-reinforced responses following lever presses that led to an escape from shock. As vulnerability factors, behavioral inhibition and female sex were each associated with more prevalent reinforced and non-reinforced avoidant behavior, but an additive effect of these 2 factors was not observed. These data illustrate the importance of genetics (both strain and sex) in the assessment and modeling of anxiety vulnerability through the acquisition of active-avoidance responses and the persistence of emitting those responses in periods of non-reinforcement.

  19. PSD Camera Based Position and Posture Control of Redundant Robot Considering Contact Motion

    NASA Astrophysics Data System (ADS)

    Oda, Naoki; Kotani, Kentaro

    The paper describes a position and posture controller design based on the absolute position by external PSD vision sensor for redundant robot manipulator. The redundancy enables a potential capability to avoid obstacle while continuing given end-effector jobs under contact with middle link of manipulator. Under contact motion, the deformation due to joint torsion obtained by comparing internal and external position sensor, is actively suppressed by internal/external position hybrid controller. The selection matrix of hybrid loop is given by the function of the deformation. And the detected deformation is also utilized in the compliant motion controller for passive obstacle avoidance. The validity of the proposed method is verified by several experimental results of 3link planar redundant manipulator.

  20. New spatial cognition tests for mice: passive place avoidance on stable and active place avoidance on rotating arenas.

    PubMed

    Cimadevilla, J M; Fenton, A A; Bures, J

    2001-03-15

    Dry arenas are a convenient tool for assessing the spatial navigation abilities of rodents. In this paper, mice must avoid a punished sector of a dry arena from which they are expelled by a puff of compressed air. The position of the punished sector is defined relative to the coordinate system of the room. In a stable environment the mice can use both extramaze and intramaze landmarks to orient themselves accurately. However, when the shock area is defined by extramaze landmarks, continuous rotation of the arena at 1 rpm makes it impossible to solve the avoidance task using arena-based cues or idiothesis. The avoidance can only be solved by paying attention to extramaze cues. Our protocol tested spatial abilities on stable and rotating arenas. The acquisition of the task was manifested under both conditions by a significant improvement of performance within the first session (short-term memory component) and at the beginning of the 24-h delayed second session (long-term memory component).

  1. Functional Extended Redundancy Analysis

    ERIC Educational Resources Information Center

    Hwang, Heungsun; Suk, Hye Won; Lee, Jang-Han; Moskowitz, D. S.; Lim, Jooseop

    2012-01-01

    We propose a functional version of extended redundancy analysis that examines directional relationships among several sets of multivariate variables. As in extended redundancy analysis, the proposed method posits that a weighed composite of each set of exogenous variables influences a set of endogenous variables. It further considers endogenous…

  2. Coaxial Redundant Drives

    NASA Technical Reports Server (NTRS)

    Brissette, R.

    1983-01-01

    Harmonic drives allow redundancy and high out put torque in small package. If main drive fails, standby drive takes over and produces torque along same axis as main drive. Uses include power units in robot for internal pipeline inspection, manipulators in deep submersible probes or other applications in which redundancy protects against costly failures.

  3. The Role of Amygdala Nuclei in the Expression of Auditory Signaled Two-Way Active Avoidance in Rats

    ERIC Educational Resources Information Center

    Choi, June-Seek; Cain, Christopher K.; LeDoux, Joseph E.

    2010-01-01

    Using a two-way signaled active avoidance (2-AA) learning procedure, where rats were trained in a shuttle box to avoid a footshock signaled by an auditory stimulus, we tested the contributions of the lateral (LA), basal (B), and central (CE) nuclei of the amygdala to the expression of instrumental active avoidance conditioned responses (CRs).…

  4. Interhemispheric transfer of extinction of the active avoidance reaction in rats.

    PubMed

    Islam, S; Bures, J; Buresová, O

    1975-07-01

    Cortical spreading depression (CSD) was employed in rats to study the lateralization of extinction of a jumping avoidance reaction. Under unilateral CSD, 181 nonreinforced trials were needed to extinguish the avoidance reaction acquired in three 100-trial sessions of intact-brain training. During a second extinction session, either with the same or with the contralateral hemisphere depressed, the mean number of trials to the extinction criterion (9/10) was 39 (n = 12) or 186 (n = 15), respectively. Five extinction trials performed with the brain intact 1 hr before extinction with contralateral CSD decreased the number of trials to extinction of 98 (n = 11). Thus, extinction of active avoidance can be lateralized and interhemispherically transferred in the same way as acquisition of this habit.

  5. Resolution of seven-axis manipulator redundancy: A heuristic issue

    NASA Technical Reports Server (NTRS)

    Chen, I.

    1990-01-01

    An approach is presented for the resolution of the redundancy of a seven-axis manipulator arm from the AI and expert systems point of view. This approach is heuristic, analytical, and globally resolves the redundancy at the position level. When compared with other approaches, this approach has several improved performance capabilities, including singularity avoidance, repeatability, stability, and simplicity.

  6. Mindfulness, Physical Activity and Avoidance of Secondhand Smoke: A Study of College Students in Shanghai

    PubMed Central

    Gao, Yu; Shi, Lu

    2015-01-01

    Introduction: To better understand the documented link between mindfulness and longevity, we examine the association between mindfulness and conscious avoidance of secondhand smoke (SHS), as well as the association between mindfulness and physical activity. Method: In Shanghai University of Finance and Economics (SUFE) we surveyed a convenience sample of 1516 college freshmen. We measured mindfulness, weekly physical activity, and conscious avoidance of secondhand smoke, along with demographic and behavioral covariates. We used a multilevel logistic regression to test the association between mindfulness and conscious avoidance of secondhand smoke, and used a Tobit regression model to test the association between mindfulness and metabolic equivalent hours per week. In both models the home province of the student respondent was used as the cluster variable, and demographic and behavioral covariates, such as age, gender, smoking history, household registration status (urban vs. rural), the perceived smog frequency in their home towns, and the asthma diagnosis. Results: The logistic regression of consciously avoiding SHS shows that a higher level of mindfulness was associated with an increase in the odds ratio of conscious SHS avoidance (logged odds: 0.22, standard error: 0.07, p < 0.01). The Tobit regression shows that a higher level of mindfulness was associated with more metabolic equivalent hours per week (Tobit coefficient: 4.09, standard error: 1.13, p < 0.001). Discussion: This study is an innovative attempt to study the behavioral issue of secondhand smoke from the perspective of the potential victim, rather than the active smoker. The observed associational patterns here are consistent with previous findings that mindfulness is associated with healthier behaviors in obesity prevention and substance use. Research designs with interventions are needed to test the causal link between mindfulness and these healthy behaviors. PMID:26308029

  7. Telencephalic neural activation following passive avoidance learning in a terrestrial toad.

    PubMed

    Puddington, Martín M; Daneri, M Florencia; Papini, Mauricio R; Muzio, Rubén N

    2016-12-15

    The present study explores passive avoidance learning and its neural basis in toads (Rhinella arenarum). In Experiment 1, two groups of toads learned to move from a lighted compartment into a dark compartment. After responding, animals in the experimental condition were exposed to an 800-mM strongly hypertonic NaCl solution that leads to weight loss. Control animals received exposure to a 300-mM slightly hypertonic NaCl solution that leads to neither weight gain nor loss. After 10 daily acquisition trials, animals in the experimental group showed significantly longer latency to enter the dark compartment. Additionally, 10 daily trials in which both groups received the 300-mM NaCl solution after responding eliminated this group effect. Thus, experimental animals showed gradual acquisition and extinction of a passive avoidance respond. Experiment 2 replicated the gradual acquisition effect, but, after the last trial, animals were sacrificed and neural activation was assessed in five brain regions using AgNOR staining for nucleoli-an index of brain activity. Higher activation in the experimental animals, relative to controls, was observed in the amygdala and striatum. Group differences in two other regions, lateral pallium and septum, were borderline, but nonsignificant, whereas group differences in the medial pallium were nonsignificant. These preliminary results suggest that a striatal-amygdala activation could be a key component of the brain circuit controlling passive avoidance learning in amphibians. The results are discussed in relation to the results of analogous experiments with other vertebrates.

  8. Inhibition of memory consolidation after active avoidance conditioning by antisense intervention with ependymin gene expression.

    PubMed

    Schmidt, R; Brysch, W; Rother, S; Schlingensiepen, K H

    1995-10-01

    A rapid increase in ependymin mRNA expression demonstrated by semiquantitative in situ hybridization after avoidance conditioning on goldfish suggested a molecular demand for newly synthesized ependymin translation product. To inhibit de novo synthesis of ependymin molecules without interference with preexisting ones, 18 mer anti-ependymin mRNA-phosphorothioate oligodeoxynucleotides (S-ODNs) were injected into the perimeningeal brain fluid before active avoidance training. S-ODN-injected animals learned the avoidance response; however, they were amnesic in the test. When injected into overtrained animals, S-ODNs did not interfere with retrieval or performance of the avoidance response. Fish treated with randomized S-ODN sequences served as further controls. Incorporation of S-ODNs was analyzed by injection of fluorescein isothiocyanate (FITC)-conjugated oligodeoxynucleotide probes. Microscopic observation revealed strong FITC-S-ODN fluorescence in reticular-shaped fibroblasts, the only known site of ependymin synthesis. Results demonstrate that selective inhibition of ependymin gene expression in vivo can specifically prevent memory formation. We conclude that in particular the newly synthesized ependymin molecules are involved in memory consolidation, possibly because they have not yet undergone irreversible molecular changes, which have been reported of this glycoprotein in a low-calcium microenvironment.

  9. Functional redundancy between the transcriptional activation domains of E2A is mediated by binding to the KIX domain of CBP/p300.

    PubMed

    Denis, Christopher M; Langelaan, David N; Kirlin, Alyssa C; Chitayat, Seth; Munro, Kim; Spencer, Holly L; LeBrun, David P; Smith, Steven P

    2014-06-01

    The E-protein transcription factors play essential roles in lymphopoiesis, with E12 and E47 (hereafter called E2A) being particularly important in B cell specification and maturation. The E2A gene is also involved in a chromosomal translocation that results in the leukemogenic oncoprotein E2A-PBX1. The two activation domains of E2A, AD1 and AD2, display redundant, independent, and cooperative functions in a cell-dependent manner. AD1 of E2A functions by binding the transcriptional co-activator CBP/p300; this interaction is required in oncogenesis and occurs between the conserved ϕ-x-x-ϕ-ϕ motif in AD1 and the KIX domain of CBP/p300. However, co-activator recruitment by AD2 has not been characterized. Here, we demonstrate that the first of two conserved ϕ-x-x-ϕ-ϕ motifs within AD2 of E2A interacts at the same binding site on KIX as AD1. Mutagenesis uncovered a correspondence between the KIX-binding affinity of AD2 and transcriptional activation. Although AD2 is dispensable for oncogenesis, experimentally increasing the affinity of AD2 for KIX uncovered a latent potential to mediate immortalization of primary hematopoietic progenitors by E2A-PBX1. Our findings suggest that redundancy between the two E2A activation domains with respect to transcriptional activation and oncogenic function is mediated by binding to the same surface of the KIX domain of CBP/p300.

  10. Avoidant symptoms in PTSD predict fear circuit activation during multimodal fear extinction.

    PubMed

    Sripada, Rebecca K; Garfinkel, Sarah N; Liberzon, Israel

    2013-01-01

    Convergent evidence suggests that individuals with posttraumatic stress disorder (PTSD) exhibit exaggerated avoidance behaviors as well as abnormalities in Pavlonian fear conditioning. However, the link between the two features of this disorder is not well understood. In order to probe the brain basis of aberrant extinction learning in PTSD, we administered a multimodal classical fear conditioning/extinction paradigm that incorporated affectively relevant information from two sensory channels (visual and tactile) while participants underwent fMRI scanning. The sample consisted of fifteen OEF/OIF veterans with PTSD. In response to conditioned cues and contextual information, greater avoidance symptomatology was associated with greater activation in amygdala, hippocampus, vmPFC, dmPFC, and insula, during both fear acquisition and fear extinction. Heightened responses to previously conditioned stimuli in individuals with more severe PTSD could indicate a deficiency in safety learning, consistent with PTSD symptomatology. The close link between avoidance symptoms and fear circuit activation suggests that this symptom cluster may be a key component of fear extinction deficits in PTSD and/or may be particularly amenable to change through extinction-based therapies.

  11. Children's Avoidance of Interrupting Others' Activities in Requesting Help: Cultural Aspects of Considerateness.

    PubMed

    Ruvalcaba, Omar; Rogoff, Barbara; López, Angélica; Correa-Chávez, Maricela; Gutiérrez, Kris

    2015-01-01

    To be able to collaborate skillfully, people need to coordinate well with others, taking into account how their actions fit with those of their partners. This is a key aspect of an approach to learning called Learning by Observing and Pitching In, hypothesized to be common in many Indigenous-heritage communities of the Americas. This chapter considers cultural values that emphasize considerateness and awareness of how one's actions impact others such as the Mexican cultural value of respeto and cultural differences in children's efforts to avoid interrupting others' activity. US Mexican-heritage children showed more evidence of avoiding interrupting the ongoing activity of an adult when they requested help, compared with European American children from families with extensive schooling experience. Most of the Mexican-heritage children's requests for help that gave evidence of avoiding interruption were made nonverbally, which may facilitate unobtrusive requests. There were no significant differences among children from two US Mexican-heritage backgrounds varying in experience with Western schooling and likely experience with Indigenous-American practices, suggesting that the Mexican cultural value of respeto and associated considerateness is widespread even among US Mexican-heritage families with extensive experience with Western schooling and life in the United States.

  12. Gustatory-mediated avoidance of bacterial lipopolysaccharides via TRPA1 activation in Drosophila

    PubMed Central

    Soldano, Alessia; Alpizar, Yeranddy A; Boonen, Brett; Franco, Luis; López-Requena, Alejandro; Liu, Guangda; Mora, Natalia; Yaksi, Emre; Voets, Thomas; Vennekens, Rudi; Hassan, Bassem A; Talavera, Karel

    2016-01-01

    Detecting pathogens and mounting immune responses upon infection is crucial for animal health. However, these responses come at a high metabolic price (McKean and Lazzaro, 2011, Kominsky et al., 2010), and avoiding pathogens before infection may be advantageous. The bacterial endotoxins lipopolysaccharides (LPS) are important immune system infection cues (Abbas et al., 2014), but it remains unknown whether animals possess sensory mechanisms to detect them prior to infection. Here we show that Drosophila melanogaster display strong aversive responses to LPS and that gustatory neurons expressing Gr66a bitter receptors mediate avoidance of LPS in feeding and egg laying assays. We found the expression of the chemosensory cation channel dTRPA1 in these cells to be necessary and sufficient for LPS avoidance. Furthermore, LPS stimulates Drosophila neurons in a TRPA1-dependent manner and activates exogenous dTRPA1 channels in human cells. Our findings demonstrate that flies detect bacterial endotoxins via a gustatory pathway through TRPA1 activation as conserved molecular mechanism. DOI: http://dx.doi.org/10.7554/eLife.13133.001 PMID:27296646

  13. Visual processing of nonlinguistic strings: redundancy effects and reading ability.

    PubMed

    Mason, M; Katz, L

    1976-12-01

    Visual redundancy effects were investigated in two experiments using nonalphabetic material. Experiment 1 had adult subjects search for the presence or absence of a predetermined target symbol through single six-symbol linear arrays. Reaction times were significantly faster in both a distributional redundancy and a spatial redundancy condition than in a no-redundancy condition. Experiment 2 had good and poor sixth-grade readers serve in the no-redundancy and spatial redundancy conditions of Experment 1. Poor readers were equivalent to good readers in the no-redundancy condition but were significantly slower in the spatial redundancy condition. Thus, spatial redundancy was shown to be operative in single symbol search time in a paradigm that avoided confounding by higher order linguistic variables. The present experiments, in conjunction with prior findings that good and poor readers differ in letter search time by their ability to use spatial redundancy, suggest that processes involved in the component skill of letter identification cannot be considered trivial to the reading process.

  14. High precision redundant robotic manipulator

    DOEpatents

    Young, K.K.D.

    1998-09-22

    A high precision redundant robotic manipulator for overcoming contents imposed by obstacles or imposed by a highly congested work space is disclosed. One embodiment of the manipulator has four degrees of freedom and another embodiment has seven degrees of freedom. Each of the embodiments utilize a first selective compliant assembly robot arm (SCARA) configuration to provide high stiffness in the vertical plane, a second SCARA configuration to provide high stiffness in the horizontal plane. The seven degree of freedom embodiment also utilizes kinematic redundancy to provide the capability of avoiding obstacles that lie between the base of the manipulator and the end effector or link of the manipulator. These additional three degrees of freedom are added at the wrist link of the manipulator to provide pitch, yaw and roll. The seven degrees of freedom embodiment uses one revolute point per degree of freedom. For each of the revolute joints, a harmonic gear coupled to an electric motor is introduced, and together with properly designed based servo controllers provide an end point repeatability of less than 10 microns. 3 figs.

  15. High precision redundant robotic manipulator

    DOEpatents

    Young, Kar-Keung David

    1998-01-01

    A high precision redundant robotic manipulator for overcoming contents imposed by obstacles or imposed by a highly congested work space. One embodiment of the manipulator has four degrees of freedom and another embodiment has seven degreed of freedom. Each of the embodiments utilize a first selective compliant assembly robot arm (SCARA) configuration to provide high stiffness in the vertical plane, a second SCARA configuration to provide high stiffness in the horizontal plane. The seven degree of freedom embodiment also utilizes kinematic redundancy to provide the capability of avoiding obstacles that lie between the base of the manipulator and the end effector or link of the manipulator. These additional three degrees of freedom are added at the wrist link of the manipulator to provide pitch, yaw and roll. The seven degrees of freedom embodiment uses one revolute point per degree of freedom. For each of the revolute joints, a harmonic gear coupled to an electric motor is introduced, and together with properly designed based servo controllers provide an end point repeatability of less than 10 microns.

  16. Equalization in redundant channels

    NASA Technical Reports Server (NTRS)

    Tulpule, Bhalchandra R. (Inventor); Collins, Robert E. (Inventor); Cominelli, Donald F. (Inventor); O'Neill, Richard D. (Inventor)

    1988-01-01

    A miscomparison between a channel's configuration data base and a voted system configuration data base in a redundant channel system having identically operating, frame synchronous channels triggers autoequalization of the channel's historical signal data bases in a hierarchical, chronological manner with that of a correctly operating channel. After equalization, symmetrization of the channel's configuration data base with that of the system permits upgrading of the previously degraded channel to full redundancy. An externally provided equalization command, e.g., manually actuated, can also trigger equalization.

  17. Telencephalic neural activation following passive avoidance learning in a terrestrial toad.

    PubMed

    Puddington, Martín M; Daneri, M Florencia; Papini, Mauricio R; Muzio, Rubén N

    2016-12-15

    The present study explores passive avoidance learning and its neural basis in toads (Rhinella arenarum). In Experiment 1, two groups of toads learned to move from a lighted compartment into a dark compartment. After responding, animals in the experimental condition were exposed to an 800-mM strongly hypertonic NaCl solution that leads to weight loss. Control animals received exposure to a 300-mM slightly hypertonic NaCl solution that leads to neither weight gain nor loss. After 10 daily acquisition trials, animals in the experimental group showed significantly longer latency to enter the dark compartment. Additionally, 10 daily trials in which both groups received the 300-mM NaCl solution after responding eliminated this group effect. Thus, experimental animals showed gradual acquisition and extinction of a passive avoidance respond. Experiment 2 replicated the gradual acquisition effect, but, after the last trial, animals were sacrificed and neural activation was assessed in five brain regions using AgNOR staining for nucleoli-an index of brain activity. Higher activation in the experimental animals, relative to controls, was observed in the amygdala and striatum. Group differences in two other regions, lateral pallium and septum, were borderline, but nonsignificant, whereas group differences in the medial pallium were nonsignificant. These preliminary results suggest that a striatal-amygdala activation could be a key component of the brain circuit controlling passive avoidance learning in amphibians. The results are discussed in relation to the results of analogous experiments with other vertebrates. PMID:27498147

  18. Redundancy of hydraulic flight control actuators

    NASA Technical Reports Server (NTRS)

    Chenoweth, C. C.; Ryder, D. R.

    1976-01-01

    The constraint of requiring airplanes to have inherent aerodynamic stability can be removed by using active control systems. The resulting airplane requires control system reliability approaching that of the basic airframe. Redundant control actuators can be used to achieve the required reliability, but create mechanization and operational problems. Of numerous candidate systems, two different approaches to solving the problems associated with redundant actuators which appear the most likely to be used in advanced airplane control systems are described.

  19. Potassium inhibits nitric oxide and adenosine arteriolar vasodilatation via K(IR) and Na(+)/K(+) ATPase: implications for redundancy in active hyperaemia.

    PubMed

    Lamb, Iain R; Murrant, Coral L

    2015-12-01

    Redundancy, in active hyperaemia, where one vasodilator can compensate for another if the first is missing, would require that one vasodilator inhibits the effects of another; therefore, if the first vasodilator is inhibited, its inhibitory influence on the second vasodilator is removed and the second vasodilator exerts a greater vasodilatory effect. We aimed to determine whether vasodilators relevant to skeletal muscle contraction [potassium chloride (KCl), adenosine (ADO) and nitric oxide] inhibit one another and, in addition, to investigate the mechanisms for this interaction. We used the hamster cremaster muscle and intravital microscopy to directly visualize 2A arterioles when exposed to a range of concentrations of one vasodilator [10(-8) to 10(-5) M S-nitroso-N-acetyl penicillamine (SNAP), 10(-8) to 10(-5) M ADO, 10 and 20 mM KCl] in the absence and then in the presence of a second vasodilator (10(-7) M ADO, 10(-7) M SNAP, 10 mM KCl). We found that KCl significantly attenuated SNAP-induced vasodilatations by ∼65.8% and vasodilatations induced by 10(-8) to 10(-6) M ADO by ∼72.8%. Furthermore, we observed that inhibition of KCl vasodilatation, by antagonizing either Na(+)/K(+) ATPase using ouabain or inward rectifying potassium channels using barium chloride, could restore the SNAP-induced vasodilatation by up to ∼53.9% and 30.6%, respectively, and also restore the ADO-induced vasodilatations by up to ∼107% and 76.7%, respectively. Our data show that vasodilators relevant to muscle contraction can interact in a way that alters the effectiveness of other vasodilators. These data suggest that active hyperaemia may be the result of complex interactions between multiple vasodilators via a redundant control paradigm.

  20. Socio-demographic, health-related and psychosocial correlates of fear of falling and avoidance of activity in community-living older persons who avoid activity due to fear of falling

    PubMed Central

    Kempen, Gertrudis IJM; van Haastregt, Jolanda CM; McKee, Kevin J; Delbaere, Kim; Zijlstra, GA Rixt

    2009-01-01

    Background Fear of falling and avoidance of activity are common in old age and are suggested to be (public) health problems of equal importance to falls. Earlier studies of correlates of fear of falling and avoidance of activity did hardly differentiate between severe and mild levels of fear of falling and avoidance of activity which may be relevant from clinical point of view. Furthermore, most studies focused only on socio-demographics and/or health-related variables and hardly incorporated an extensive range of potential correlates of fear of falling including psychosocial variables. This study analyzes the univariate and multivariate associations between five socio-demographic, seven health-related and six psychosocial variables and levels of fear of falling and avoidance of activity in older persons who avoid activity due to fear of falling. Methods Cross-sectional study in 540 community-living older people aged ≥ 70 years with at least mild fear of falling and avoidance of activity. Chi-squares, t-tests and logistics regression analyses were performed to study the associations between the selected correlates and both outcomes. Results Old age, female sex, limitations in activity of daily living, impaired vision, poor perceived health, chronic morbidity, falls, low general self-efficacy, low mastery, loneliness, feelings of anxiety and symptoms of depression were identified as univariate correlates of severe fear of falling and avoidance of activity. Female sex, limitations in activity of daily living and one or more falls in the previous six months correlated independently with severe fear of falling. Higher age and limitations in activity of daily living correlated independently with severe avoidance of activity. Conclusion Psychosocial variables did not contribute independently to the difference between mild and severe fear of falling and to the difference between mild and severe avoidance of activity due to fear of falling. Although knowledge about the

  1. Time Out from Sex or Romance: Sexually Experienced Adolescents' Decisions to Purposefully Avoid Sexual Activity or Romantic Relationships.

    PubMed

    Byers, E Sandra; O'Sullivan, Lucia F; Brotto, Lori A

    2016-05-01

    Researchers have given significant attention to abstinence among adolescents, but far less is known about purposeful avoidance of sexual activity (and relationship involvement). Typically, it is assumed that, once adolescents have initiated sexual activity, they will thereafter engage in sexual activity if given the opportunity. However, it is unclear whether that is true as some research indicates that many adolescents engage in sexual activity intermittently. Sexually experienced adolescents may purposefully avoid engaging in sexual activity for a period of time and, if so, this has implications for understanding their sexual decision-making. We used a mixed methods approach to investigate sexually experienced adolescents' decisions to purposefully avoid further sexual activity and/or romantic relationships with a focus on how common these decisions are and factors influencing them. Participants were 411 (56 % female) adolescents (16-21 years old) who completed an on-line survey that assessed reasons for each type of avoidance, religiosity, sexual esteem, sexual distress, sexual coercion, and dysfunctional sexual beliefs. Overall, 27 % of participants had engaged in sexual avoidance and 47 % had engaged in romantic avoidance. Significantly more female than male adolescents reported sexual and romantic avoidance. Adolescents' reasons for sexual avoidance included: lack of sexual pleasure or enjoyment, relationship reasons, negative emotions, values, fear of negative outcomes, negative physical experience, and other priorities. Reasons for romantic avoidance included: effects of previous relationship, not interested in commitment, wrong time, other priorities, negative emotions, no one was good enough, and sexual concerns. Logistical regressions were used to assess associations between age, religiosity, sexual esteem, sexual distress, experience of sexual coercion, and dysfunctional sexual beliefs and having engaged in romantic and/or sexual avoidance. The

  2. Time Out from Sex or Romance: Sexually Experienced Adolescents' Decisions to Purposefully Avoid Sexual Activity or Romantic Relationships.

    PubMed

    Byers, E Sandra; O'Sullivan, Lucia F; Brotto, Lori A

    2016-05-01

    Researchers have given significant attention to abstinence among adolescents, but far less is known about purposeful avoidance of sexual activity (and relationship involvement). Typically, it is assumed that, once adolescents have initiated sexual activity, they will thereafter engage in sexual activity if given the opportunity. However, it is unclear whether that is true as some research indicates that many adolescents engage in sexual activity intermittently. Sexually experienced adolescents may purposefully avoid engaging in sexual activity for a period of time and, if so, this has implications for understanding their sexual decision-making. We used a mixed methods approach to investigate sexually experienced adolescents' decisions to purposefully avoid further sexual activity and/or romantic relationships with a focus on how common these decisions are and factors influencing them. Participants were 411 (56 % female) adolescents (16-21 years old) who completed an on-line survey that assessed reasons for each type of avoidance, religiosity, sexual esteem, sexual distress, sexual coercion, and dysfunctional sexual beliefs. Overall, 27 % of participants had engaged in sexual avoidance and 47 % had engaged in romantic avoidance. Significantly more female than male adolescents reported sexual and romantic avoidance. Adolescents' reasons for sexual avoidance included: lack of sexual pleasure or enjoyment, relationship reasons, negative emotions, values, fear of negative outcomes, negative physical experience, and other priorities. Reasons for romantic avoidance included: effects of previous relationship, not interested in commitment, wrong time, other priorities, negative emotions, no one was good enough, and sexual concerns. Logistical regressions were used to assess associations between age, religiosity, sexual esteem, sexual distress, experience of sexual coercion, and dysfunctional sexual beliefs and having engaged in romantic and/or sexual avoidance. The

  3. [The dependence of learning an active avoidance reaction on overcoming a problem-solving situation in a shuttle box].

    PubMed

    Savonenko, A V; Zieliński, K

    1998-01-01

    The two-way avoidance procedure dramatically differs from the one-way procedure in rate of learning. The present study was conducted to prove that retardation of the two-way avoidance acquisition resulted from development of the behavioral conflict tendency not to reenter the previous shock compartment. Cluster analysis of avoidance response indices divided rats into three distinctive classes. The occurrence of avoidance, escape, and freezing responses in the first session was analyzed in these three groups. Freezing during the shock action reflected the conflict tendency and showed a negative correlation with avoidance response indices. Only the rats which overcame the conflict and performed at least one avoidance reaction toward the end of the first session significantly improved their avoidance score in the following session. Discriminant analysis of indices of the three reaction types in the first session revealed sufficiency of these indices for prediction of the success in avoidance learning in subsequent sessions. Our results proved the hypothesis formulated previously that the conflict situation inherent to the two-way shuttle box procedure retarded the active avoidance acquisition. A number of trials have to be reserved in the first session for solving the conflict situation (direct effect on the rate of learning). The conflict intensity which directly effects the avoidance performance in the first session, presumably, influences learning in subsequent sessions (secondary effect on learning).

  4. Redundancy and Transposition in English.

    ERIC Educational Resources Information Center

    Sarhady, T.

    2003-01-01

    Investigates the relationship between redundancy and transposition in scientific texts. Highlights different traditional and discoursal theories of redundancy. Analyzed 20 self-contained scientific texts; results show that most of the sample texts follow similar organization. (Author/VWL)

  5. Remote Maneuver of Space Debris Using Photon Pressure for Active Collision Avoidance

    NASA Astrophysics Data System (ADS)

    Smith, C.

    2014-09-01

    The Space Environment Research Corporation (SERC) is a consortium of companies and research institutions that have joined together to pursue research and development of technologies and capabilities that will help to preserve the orbital space environment. The consortium includes, Electro Optics Systems (Australia), Lockheed Martin Australia, Optus Satellite Systems (Australia), The Australian national University, RMIT University, National Institute of Information and Communications Technology (NICT, Japan) as well as affiliates from NASA Ames and ESA. SERC is also the recipient of and Australian Government Cooperative Research Centre grant. SERC will pursue a wide ranging research program including technologies to improve tracking capability and capacity, orbit determination and propagation algorithms, conjunction analysis and collision avoidance. All of these technologies will contribute to the flagship program to demonstrate active collision avoidance using photon pressure to provide remote maneuver of space debris. This project joins of the proposed NASA Lightforce concept with infrastructure and capabilities provided by SERC. This paper will describe the proposed research and development program to provide an on-orbit demonstration within the next five years for remote maneuver of space debris.

  6. Patterns of Theta Activity in Limbic Anxiety Circuit Preceding Exploratory Behavior in Approach-Avoidance Conflict

    PubMed Central

    Jacinto, Luis R.; Cerqueira, João J.; Sousa, Nuno

    2016-01-01

    Theta oscillations within the hippocampus-amygdala-medial prefrontal cortex (HPC-AMY-mPFC) circuit have been consistently implicated in the regulation of anxiety behaviors, including risk-assessment. To study if theta activity during risk-assessment was correlated with exploratory behavior in an approach/avoidance paradigm we recorded simultaneous local field potentials from this circuit in rats exploring the elevated-plus maze (EPM). Opposing patterns of power variations in the ventral hippocampus (vHPC), basolateral amygdala (BLA), and prelimbic (PrL) mPFC, but not in the dorsal hippocampus (dHPC), during exploratory risk-assessment of the open arms preceded further exploration of the open arms or retreat back to the safer closed arms. The same patterns of theta power variations in the HPC-BLA-mPFC(PrL) circuit were also displayed by animals submitted to chronic unpredictable stress protocol known to induce an anxious state. Diverging patterns of vHPC-mPFC(PrL) theta coherence were also significantly correlated with forthcoming approach or avoidance behavior in the conflict situation in both controls and stressed animals; interestingly, vHPC-BLA, and BLA-mPFC(PrL) theta coherence correlated with future behavior only in stressed animals, underlying the pivotal role of the amygdala on the stress response. PMID:27713693

  7. Src kinase activity is required for avoidance memory formation and recall.

    PubMed

    Bevilaqua, L R M; Rossato, J I; Medina, J H; Izquierdo, I; Cammarota, M

    2003-12-01

    Using 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-D]pyrimidine (PP2), a specific inhibitor of the Src family of tyrosine kinases, here we show a direct involvement of these enzymes in memory formation and recall. When infused into the CA1 region of the dorsal hippocampus, immediately or 30 min after training rats in a one-trial inhibitory avoidance task, PP2 but not its inactive analog 4-amino-7-phenylpyrazol[3,4-D]pyrimidine (PP3), blocked short- (STM) and long-term memory (LTM) formation, as tested 2 or 24 h post-training, respectively. PP2 had no effect on STM when given at 60 min post-training or on LTM when administered at 60, 120 or 180 min after the training session, but blocked memory recall when infused into CA1 15 min before a LTM expression test. Hence, activity of the Src family of tyrosine kinases is required in the CA1 region of the rat dorsal hippocampus for the normal formation and retrieval of one-trial inhibitory avoidance memory.

  8. Behavioral effects of cocoa and its main active compound theobromine: evaluation by ambulatory activity and discrete avoidance in mice.

    PubMed

    Kuribara, H; Tadokoro, S

    1992-04-01

    Effects of cocoa and its main CNS active constituent methylxanthine theobromine as well as caffeine were evaluated by ambulatory activity, and discrete lever-press and shuttle avoidance in mice. Cocoa (1 g/kg p.o.) and theobromine (10 mg/kg p.o.) significantly increased ambulatory activity. However, the other doses of cocoa and theobromine had no effect on the ambulatory activity. Caffeine increased ambulatory activity with the maximum action at 30 mg/kg p.o. Furthermore, cocoa (0.1, 0.3 and 1 g/kg), theobromine (3, 10, 30 and 100 mg/kg) and caffeine (3, 10, 30 and 100 mg/kg) enhanced the ambulation-increasing effect of methamphetamine (2 mg/kg s.c.). The ambulation-increasing effect of cocaine (20 mg/kg s.c.) was also enhanced by cocoa (1 g/kg), theobromine (10, 30 and 100 mg/kg) and caffeine (10, 30 and 100 mg/kg). On the other hand, comparatively higher doses of theobromine and caffeine disrupted the well established avoidance response. Thus, the avoidance rate was significantly decreased by theobromine (100 mg/kg and more) and caffeine (30 mg/kg and more) under the lever-press situation, and by theobromine (100 mg/kg and more) and caffeine (100 mg/kg) under the shuttle situation. These dose effect relationships revealed that cocoa contains about 1% theobromine. The present results indicate that we may receive the CNS action of theobromine through consumption of theobromine-containing foodstuffs or beverages in our every day life. PMID:1586288

  9. Hippocampus and two-way active avoidance conditioning: Contrasting effects of cytotoxic lesion and temporary inactivation.

    PubMed

    Wang, Jia; Bast, Tobias; Wang, Yu-Cong; Zhang, Wei-Ning

    2015-12-01

    Hippocampal lesions tend to facilitate two-way active avoidance (2WAA) conditioning, where rats learn to cross to the opposite side of a conditioning chamber to avoid a tone-signaled footshock. This classical finding has been suggested to reflect that hippocampus-dependent place/context memory inhibits 2WAA (a crossing response to the opposite side is inhibited by the memory that this is the place where a shock was received on the previous trial). However, more recent research suggests other aspects of hippocampal function that may support 2WAA learning. More specifically, the ventral hippocampus has been shown to contribute to behavioral responses to aversive stimuli and to positively modulate the meso-accumbens dopamine system, whose activation has been implicated in 2WAA learning. Permanent hippocampal lesions may not reveal these contributions because, following complete and permanent loss of hippocampal output, other brain regions may mediate these processes or because deficits could be masked by lesion-induced extra-hippocampal changes, including an upregulation of accumbal dopamine transmission. Here, we re-examined the hippocampal role in 2WAA learning in Wistar rats, using permanent NMDA-induced neurotoxic lesions and temporary functional inhibition by muscimol or tetrodotoxin (TTX) infusion. Complete hippocampal lesions tended to facilitate 2WAA learning, whereas ventral (VH) or dorsal hippocampal (DH) lesions had no effect. In contrast, VH or DH muscimol or TTX infusions impaired 2WAA learning. Ventral infusions caused an immediate impairment, whereas after dorsal infusions rats showed intact 2WAA learning for 40-50 min, before a marked deficit emerged. These data show that functional inhibition of ventral hippocampus disrupts 2WAA learning, while the delayed impairment following dorsal infusions may reflect the time required for drug diffusion to ventral hippocampus. Overall, using temporary functional inhibition, our study shows that the ventral

  10. Active faults crossing trunk pipeline routes: some important steps to avoid the disaster

    NASA Astrophysics Data System (ADS)

    Besstrashnov, Vladimir; Strom, Alexander

    2010-05-01

    Trunk pipelines that pass through tectonically active areas connecting oil and gas reservoirs with terminals and refineries cross active faults that can produce large earthquakes. Besides strong motion affecting vast areas, these earthquakes are often associated with surface faulting that provides additional hazard to pipelines. To avoid significant economic losses and environmental pollution, pipelines should be designed to sustain both effects (shaking and direct rupturing) without pipe damage and spill. Special studies aimed to provide necessary input data for the designers should be performed in the course of engineering survey. However, our experience on conducting and review of such studies for several oil and gas trunk pipelines in Russia show urgent need of more strict definition of basic conceptions and approaches used for identification and localization of these potentially hazardous tectonic features. Identification of active faults (fault zones) considered as causative faults - sources of strong motion caused by seismic waves that affect dozens kilometers of pipeline route can be done by use of both direct and indirect evidence of Late Pleistocene - Holocene activity of faults and fault zones. Since strong motion parameters can be considered as constant within the near-field zone, which width in case of large earthquake is up to dozens kilometers, accuracy of active fault location is not so critical and ±1-2 km precision provided by use of indirect evidence is acceptable. In contrast, if one have to identify and characterize zones of potential surface rupturing that require special design of the endangered pipeline section, only direct evidence of such activity can provide reliable input data for crossing design with relevant accuracy of fault location, amount and direction of displacement. Only traces of surface faults displacing Late Pleistocene - Holocene sediments and/or geomorphic features are considered as direct evidence of fault activity. Just

  11. The effect of delta 9-tetrahydrocannabinol and LSD on the acquisition of an active avoidance response in the rat.

    PubMed

    Waser, P G; Martin, A; Heer-Carcano, L

    1976-04-15

    The course of active avoidance learning of rats in a symmetrical Y-maze under the influence of 1, 3, and 9 mg/kg of delta 9-THC i.p., and 5, 20, and mug/kg of LSD was investigated. Delta-THC in a dosage of 1 mg/kg had no effect on avoidance learning. Three to a lesser extent 9 mg/kg produced more rapid learning with a significantly better performance. Learning under delta 9-THC proved to be state-dependent. The withdrawal of delta 9-THC caused a decrease in the avoidance rate, which was dependent on the dosage. Upon renewal of the THC doses, the animals reattained their earlier preformance. In the course of the experiment there was rapid tolerance development, especially of the sedative properties of THC. LSD retarded the rate of acquisition of the active avoidance response. Whereas the control animals displayed over 80% successful active avoidance from the 14th session onwards, this was achieved by the LSD groups only after the 20th session. However, in contrast to the control group the LSD animals were able to increase their avoidance rate to over 90%, and this was maintained to the end of the experiment (a total of 24 sessions with LSD). The sudden withdrawal of LSD produced a fall in avoidance rate, which was dependent on the pervious training dosage; as with delta 9-THC state-dependent learning can also be assumed for LSD.

  12. The habenulo-raphe serotonergic circuit encodes an aversive expectation value essential for adaptive active avoidance of danger.

    PubMed

    Amo, Ryunosuke; Fredes, Felipe; Kinoshita, Masae; Aoki, Ryo; Aizawa, Hidenori; Agetsuma, Masakazu; Aoki, Tazu; Shiraki, Toshiyuki; Kakinuma, Hisaya; Matsuda, Masaru; Yamazaki, Masako; Takahoko, Mikako; Tsuboi, Takashi; Higashijima, Shin-ichi; Miyasaka, Nobuhiko; Koide, Tetsuya; Yabuki, Yoichi; Yoshihara, Yoshihiro; Fukai, Tomoki; Okamoto, Hitoshi

    2014-12-01

    Anticipation of danger at first elicits panic in animals, but later it helps them to avoid the real threat adaptively. In zebrafish, as fish experience more and more danger, neurons in the ventral habenula (vHb) showed tonic increase in the activity to the presented cue and activated serotonergic neurons in the median raphe (MR). This neuronal activity could represent the expectation of a dangerous outcome and be used for comparison with a real outcome when the fish is learning how to escape from a dangerous to a safer environment. Indeed, inhibiting synaptic transmission from vHb to MR impaired adaptive avoidance learning, while panic behavior induced by classical fear conditioning remained intact. Furthermore, artificially triggering this negative outcome expectation signal by optogenetic stimulation of vHb neurons evoked place avoidance behavior. Thus, vHb-MR circuit is essential for representing the level of expected danger and behavioral programming to adaptively avoid potential hazard.

  13. Heterogeneity in signaled active avoidance learning: substantive and methodological relevance of diversity in instrumental defensive responses to threat cues

    PubMed Central

    Galatzer-Levy, Isaac R.; Moscarello, Justin; Blessing, Esther M.; Klein, JoAnna; Cain, Christopher K.; LeDoux, Joseph E.

    2014-01-01

    Individuals exposed to traumatic stressors follow divergent patterns including resilience and chronic stress. However, researchers utilizing animal models that examine learned or instrumental threat responses thought to have translational relevance for Posttraumatic Stress Disorder (PTSD) and resilience typically use central tendency statistics that assume population homogeneity. This approach potentially overlooks fundamental differences that can explain human diversity in response to traumatic stressors. The current study tests this assumption by identifying and replicating common heterogeneous patterns of response to signaled active avoidance (AA) training. In this paradigm, rats are trained to prevent an aversive outcome (shock) by performing a learned instrumental behavior (shuttling between chambers) during the presentation of a conditioned threat cue (tone). We test the hypothesis that heterogeneous trajectories of threat avoidance provide more accurate model fit compared to a single mean trajectory in two separate studies. Study 1 conducted 3 days of signaled AA training (n = 81 animals) and study 2 conducted 5 days of training (n = 186 animals). We found that four trajectories in both samples provided the strongest model fit. Identified populations included animals that acquired and retained avoidance behavior on the first day (Rapid Avoiders: 22 and 25%); those who never successfully acquired avoidance (Non-Avoiders; 20 and 16%); a modal class who acquired avoidance over 3 days (Modal Avoiders; 37 and 50%); and a population who demonstrated a slow pattern of avoidance, failed to fully acquire avoidance in study 1 and did acquire avoidance on days 4 and 5 in study 2 (Slow Avoiders; 22.0 and 9%). With the exception of the Slow Avoiders in Study 1, populations that acquired demonstrated rapid step-like increases leading to asymptotic levels of avoidance. These findings indicate that avoidance responses are heterogeneous in a way that may be informative for

  14. The Dense Core Vesicle Protein IA-2, but not IA-2β, is Required for Active Avoidance Learning

    PubMed Central

    Carmona, Gilberto Nepthali; Nishimura, Takuya; Schindler, Charles Weber; Panlilio, Leigh Vincent; Notkins, Abner Louis

    2014-01-01

    The islet-antigens IA-2 and IA-2β are major autoantigens in type-1 diabetes and transmembrane proteins in dense core vesicles (DCV). Recently we showed that deletion of both IA-2 and IA-2β alters the secretion of hormones and neurotransmitters and impairs behavior and learning. The present study was designed to evaluate the contribution to learning of each of these genes by using single knockout (SKO) and double knockout (DKO) mice in an active avoidance test. After 5 days of training, wild type (WT) mice showed 60–70% active avoidance responses, whereas the DKO mice showed only 10–15% active avoidance responses. The degree of active avoidance responses in the IA-2 SKO mice was similar to that of the DKO mice, but in contrast, the IA-2β SKO mice behaved like WT mice showing 60–70% active avoidance responses. Molecular studies revealed a marked decrease in the phosphorylation of the cAMP Response Element-Binding Protein (CREB) and Ca2+/Calmodulin-Dependent Protein Kinase II (CAMKII) in the striatum and hippocampus of the IA-2 SKO and DKO mice, but not in the IA-2β SKO mice. To evaluate the role of CREB and CAMKII in the SKO and DKO mice, GBR-12909, which selectively blocks the dopamine uptake transporter and increases CREB and CAMKII phosphorylation, was administered. GBR-12909 restored the phosphorylation of CREB and CAMKII and increased active avoidance learning in the DKO and IA-2 SKO to near the normal levels found in the WT and IA-2β SKO mice. We conclude that in the absence of the DCV protein IA-2, active avoidance learning is impaired. PMID:24662847

  15. The dense core vesicle protein IA-2, but not IA-2β, is required for active avoidance learning.

    PubMed

    Carmona, G N; Nishimura, T; Schindler, C W; Panlilio, L V; Notkins, A L

    2014-06-01

    The islet-antigens IA-2 and IA-2β are major autoantigens in type-1 diabetes and transmembrane proteins in dense core vesicles (DCV). Recently we showed that deletion of both IA-2 and IA-2β alters the secretion of hormones and neurotransmitters and impairs behavior and learning. The present study was designed to evaluate the contribution to learning of each of these genes by using single knockout (SKO) and double knockout (DKO) mice in an active avoidance test. After 5 days of training, wild-type (WT) mice showed 60-70% active avoidance responses, whereas the DKO mice showed only 10-15% active avoidance responses. The degree of active avoidance responses in the IA-2 SKO mice was similar to that of the DKO mice, but in contrast, the IA-2β SKO mice behaved like WT mice showing 60-70% active avoidance responses. Molecular studies revealed a marked decrease in the phosphorylation of the cAMP response element-binding protein (CREB) and Ca(2+)/calmodulin-dependent protein kinase II (CAMKII) in the striatum and hippocampus of the IA-2 SKO and DKO mice, but not in the IA-2β SKO mice. To evaluate the role of CREB and CAMKII in the SKO and DKO mice, GBR-12909, which selectively blocks the dopamine uptake transporter and increases CREB and CAMKII phosphorylation, was administered. GBR-12909 restored the phosphorylation of CREB and CAMKII and increased active avoidance learning in the DKO and IA-2 SKO to near the normal levels found in the WT and IA-2β SKO mice. We conclude that in the absence of the DCV protein IA-2, active avoidance learning is impaired.

  16. Two Redundant Receptor-Like Cytoplasmic Kinases Function Downstream of Pattern Recognition Receptors to Regulate Activation of SA Biosynthesis.

    PubMed

    Kong, Qing; Sun, Tongjun; Qu, Na; Ma, Junling; Li, Meng; Cheng, Yu-Ti; Zhang, Qian; Wu, Di; Zhang, Zhibin; Zhang, Yuelin

    2016-06-01

    Salicylic acid (SA) serves as a critical signaling molecule in plant defense. Two transcription factors, SARD1 and CBP60g, control SA biosynthesis through regulating pathogen-induced expression of Isochorismate Synthase1, which encodes a key enzyme for SA biosynthesis. Here, we report that Pattern-Triggered Immunity Compromised Receptor-like Cytoplasmic Kinase1 (PCRK1) and PCRK2 function as key regulators of SA biosynthesis. In the pcrk1 pcrk2 double mutant, pathogen-induced expression of SARD1, CBP60g, and ICS1 is greatly reduced. The pcrk1 pcrk2 double mutant, but neither of the single mutants, exhibits reduced accumulation of SA and enhanced disease susceptibility to bacterial pathogens. Both PCRK1 and PCRK2 interact with the pattern recognition receptor FLS2, and treatment with pathogen-associated molecular patterns leads to rapid phosphorylation of PCRK2. Our data suggest that PCRK1 and PCRK2 function downstream of pattern recognition receptor in a signal relay leading to the activation of SA biosynthesis. PMID:27208222

  17. Active avoidance from a crude oil soluble fraction by an Andean paramo copepod.

    PubMed

    Araújo, Cristiano V M; Moreira-Santos, Matilde; Sousa, José P; Ochoa-Herrera, Valeria; Encalada, Andrea C; Ribeiro, Rui

    2014-09-01

    Several oil spills due to ruptures in the pipeline oil systems have occurred at the Andean paramo. A sample of this crude oil was mixed with water from a nearby Andean lagoon and the toxicity of the soluble fraction was assessed through lethal and avoidance assays with a locally occurring copepod (Boeckella occidentalis intermedia). The integration of mortality and avoidance aimed at predicting the immediate decline of copepod populations facing an oil leakage. The 24-h median lethal PAH concentration was 42.7 (26.4-91.6) µg L(-1). In the 12-h avoidance assay, 30% avoidance was recorded at the highest PAH concentration (19.4 µg L(-1)). The mortality at this PAH concentration would be of 25% and, thus, the population immediate decline would be of 55%. The inclusion of non-forced exposure testing with the quantification of the avoidance response in environmental risk assessments is, therefore, supported due to underestimation of the lethal assays.

  18. Avoidance and activation as keys to depression: adaptation of the Behavioral Activation for Depression Scale in a Spanish sample.

    PubMed

    Barraca, Jorge; Pérez-Alvarez, Marino; Lozano Bleda, José Héctor

    2011-11-01

    In this paper we present the adaptation of the Behavioral Activation for Depression Scale (BADS), developed by Kanter, Mulick, Busch, Berlin, and Martell (2007), in a Spanish sample. The psychometric properties were tested in a sample of 263 participants (124 clinical and 139 non-clinical). The results show that, just as in the original English version, the Spanish BADS is a valid and internally consistent scale. Construct validity was examined by correlation with the BDI-II, AAQ, ATQ, MCQ-30, STAI and EROS. Factor analysis justified the four-dimensions of the original instrument (Activation, Avoidance/Rumination, Work/School Impairment and Social Impairment), although with some differences in the factor loadings of the items. Further considerations about the usefulness of the BADS in the clinical treatment of depressed patients are also suggested.

  19. A MarR-Type Regulator Directly Activates Transcription from the Brucella abortus virB Promoter by Sharing a Redundant Role with HutC

    PubMed Central

    Arocena, Gastón M.; Zorreguieta, Angeles; Comerci, Diego J.; Ugalde, Rodolfo A.

    2012-01-01

    Type IV secretion systems (T4SS) are multiprotein structures that direct the translocation of specific molecules across the bacterial cell envelope. As in other bacteria, pathogenicity of the genus Brucella essentially depends on the integrity of the T4SS-encoding virB operon, whose expression is regulated by multiple transcription factors belonging to different families. Previously, we identified IHF and HutC, two direct regulators of the virB genes that were isolated from total protein extracts of Brucella. Here, we report the identification of MdrA, a third regulatory element that was isolated using the same screening procedure. This transcription factor, which belongs to the MarR-family of transcriptional regulators, binds at two different sites of the virB promoter and regulates expression in a growth phase-dependent manner. Like other members of the MarR family, specific ligands were able to dissociate MdrA from DNA in vitro. Determination of the MdrA-binding sites by DNase I footprinting and analyses of protein-DNA complexes by electrophoresis mobility shift assays (EMSAs) showed that MdrA competes with IHF and HutC for the binding to the promoter because their target DNA sequences overlap. Unlike IHF, both MdrA and HutC bound to the promoter without inducing bending of DNA. Moreover, the two latter transcription factors activated virB expression to similar extents, and in doing so, they are functionally redundant. Taken together, our results show that MdrA is a regulatory element that directly modulates the activity of the virB promoter and is probably involved in coordinating gene expression in response to specific environmental signals. PMID:23002224

  20. BROTHER OF FT AND TFL1 (BFT) has TFL1-like activity and functions redundantly with TFL1 in inflorescence meristem development in Arabidopsis.

    PubMed

    Yoo, Seong Jeon; Chung, Kyung Sook; Jung, Seung Hye; Yoo, So Yeon; Lee, Jong Seob; Ahn, Ji Hoon

    2010-07-01

    The FLOWERING LOCUS T (FT)/TERMINAL FLOWER 1 (TFL1) family is a small gene family that encodes important regulators that control flower development in Arabidopsis. Here, we investigated the biological role of the product of BROTHER OF FT AND TFL1 (BFT), a member of this family, whose function remains unknown. Comparison of the critical residues that play a role in distinguishing FT- or TFL1-like activity revealed that BFT is more similar to FT. Similar to FT expression, BFT expression showed a diurnal oscillation pattern, peaking in the evening. In situ hybridization revealed BFT expression in the shoot apical meristem, young leaf and axillary inflorescence meristem. Transgenic plants over-expressing BFT exhibited delayed flowering and severe floral defects (floral indeterminacy and compact inflorescences surrounded by serrate leaves), similar to 35S::TFL1 plants. LEAFY (LFY) and APETALA1 (AP1) expression was significantly reduced in 35S::BFT plants. BFT over-expression failed to rescue the terminal flower phenotype of tfl1 mutants; however, it delayed both terminal flower formation in the primary inflorescence and axillary inflorescence development in the tfl1 mutant background. Consistent with this, the loss-of-function BFT alleles, bft-2 and an BFT RNAi line, accelerated termination of the primary inflorescence and formation of axillary inflorescences in the tfl1 mutant background. Taken together, our results suggest that, despite similarities in the critical residues of BFT and FT, BFT possesses a TFL1-like activity and functions redundantly with TFL1 in inflorescence meristem development, and possibly contributes to the regulation of plant architecture.

  1. Memory retrieval of inhibitory avoidance requires histamine H1 receptor activation in the hippocampus.

    PubMed

    Fabbri, Roberta; Furini, Cristiane Regina Guerino; Passani, Maria Beatrice; Provensi, Gustavo; Baldi, Elisabetta; Bucherelli, Corrado; Izquierdo, Ivan; de Carvalho Myskiw, Jociane; Blandina, Patrizio

    2016-05-10

    Retrieval represents a dynamic process that may require neuromodulatory signaling. Here, we report that the integrity of the brain histaminergic system is necessary for retrieval of inhibitory avoidance (IA) memory, because rats depleted of histamine through lateral ventricle injections of α-fluoromethylhistidine (a-FMHis), a suicide inhibitor of histidine decarboxylase, displayed impaired IA memory when tested 2 d after training. a-FMHis was administered 24 h after training, when IA memory trace was already formed. Infusion of histamine in hippocampal CA1 of brain histamine-depleted rats (hence, amnesic) 10 min before the retention test restored IA memory but was ineffective when given in the basolateral amygdala (BLA) or the ventral medial prefrontal cortex (vmPFC). Intra-CA1 injections of selective H1 and H2 receptor agonists showed that histamine exerted its effect by activating the H1 receptor. Noteworthy, the H1 receptor antagonist pyrilamine disrupted IA memory retrieval in rats, thus strongly supporting an active involvement of endogenous histamine; 90 min after the retention test, c-Fos-positive neurons were significantly fewer in the CA1s of a-FMHis-treated rats that displayed amnesia compared with in the control group. We also found reduced levels of phosphorylated cAMP-responsive element binding protein (pCREB) in the CA1s of a-FMHis-treated animals compared with in controls. Increases in pCREB levels are associated with retrieval of associated memories. Targeting the histaminergic system may modify the retrieval of emotional memory; hence, histaminergic ligands might reduce dysfunctional aversive memories and improve the efficacy of exposure psychotherapies.

  2. Global optimum path planning for a redundant space robot

    NASA Astrophysics Data System (ADS)

    Agrawal, Om P.; Xu, Yangsheng

    1991-12-01

    Robotic manipulators will play a significant role in the maintenance and repair of space stations and satellites, and other future space missions. Robot path planning and control for the above applications should be optimum, since any inefficiency in the planning may considerably risk the success of the space mission. This paper presents a global optimum path planning scheme for redundant space robotic manipulators to be used in such missions. In this formulation, a variational approach is used to minimize the objective functional. Two optimum path planning problems are considered: first, given the end-effector trajectory, find the optimum trajectories of the joints, and second, given the terminal conditions of the end-effector, find the optimum trajectories for the end-effector and the joints. It is explicitly assumed that the gravity is zero in, and the robotic manipulator is mounted on a completely free-flying base (spacecraft) and the attitude control (reaction wheels or thrust jets) is off. Linear and angular momentum conditions for this system lead to a set of mixed holonomic an nonholonomic constraints. These equations are adjoined to the objective functional using a Lagrange multiplier technique. The formulation leads to a system of Differential and Algebraic Equations (DAEs) and a set of terminal conditions. A numerical scheme is presented for forward integration of the above system of DAEs, and an iterative shooting method is used to satisfy the terminal conditions. This approach is significant since most space robots that have been developed so far are redundant. The kinematic redundancy of space robots offers efficient control and provides the necessary dexterity for extra-vehicular activity or avoidance of potential obstacles in space stations.

  3. Redundant Design in Interdependent Networks

    PubMed Central

    2016-01-01

    Modern infrastructure networks are often coupled together and thus could be modeled as interdependent networks. Overload and interdependent effect make interdependent networks more fragile when suffering from attacks. Existing research has primarily concentrated on the cascading failure process of interdependent networks without load, or the robustness of isolated network with load. Only limited research has been done on the cascading failure process caused by overload in interdependent networks. Redundant design is a primary approach to enhance the reliability and robustness of the system. In this paper, we propose two redundant methods, node back-up and dependency redundancy, and the experiment results indicate that two measures are effective and costless. Two detailed models about redundant design are introduced based on the non-linear load-capacity model. Based on the attributes and historical failure distribution of nodes, we introduce three static selecting strategies-Random-based, Degree-based, Initial load-based and a dynamic strategy-HFD (historical failure distribution) to identify which nodes could have a back-up with priority. In addition, we consider the cost and efficiency of different redundant proportions to determine the best proportion with maximal enhancement and minimal cost. Experiments on interdependent networks demonstrate that the combination of HFD and dependency redundancy is an effective and preferred measure to implement redundant design on interdependent networks. The results suggest that the redundant design proposed in this paper can permit construction of highly robust interactive networked systems. PMID:27764174

  4. New Algorithms Manage Fourfold Redundancy

    NASA Technical Reports Server (NTRS)

    Gelderloos, H. C.

    1982-01-01

    Redundant sensors, actuators, and computers improve reliability of complex control systems, such as those in nuclear powerplants and aircraft. If one or more redundant elements fail, another takes over so that normal operation is not interrupted. Quad selection filter rejects data from null-failed and hardover-failed and hardover-failed units.

  5. Active avoidance from a crude oil soluble fraction by an Andean paramo copepod.

    PubMed

    Araújo, Cristiano V M; Moreira-Santos, Matilde; Sousa, José P; Ochoa-Herrera, Valeria; Encalada, Andrea C; Ribeiro, Rui

    2014-09-01

    Several oil spills due to ruptures in the pipeline oil systems have occurred at the Andean paramo. A sample of this crude oil was mixed with water from a nearby Andean lagoon and the toxicity of the soluble fraction was assessed through lethal and avoidance assays with a locally occurring copepod (Boeckella occidentalis intermedia). The integration of mortality and avoidance aimed at predicting the immediate decline of copepod populations facing an oil leakage. The 24-h median lethal PAH concentration was 42.7 (26.4-91.6) µg L(-1). In the 12-h avoidance assay, 30% avoidance was recorded at the highest PAH concentration (19.4 µg L(-1)). The mortality at this PAH concentration would be of 25% and, thus, the population immediate decline would be of 55%. The inclusion of non-forced exposure testing with the quantification of the avoidance response in environmental risk assessments is, therefore, supported due to underestimation of the lethal assays. PMID:24898412

  6. Symmetrization for redundant channels

    NASA Technical Reports Server (NTRS)

    Tulplue, Bhalchandra R. (Inventor); Collins, Robert E. (Inventor)

    1988-01-01

    A plurality of redundant channels in a system each contain a global image of all the configuration data bases in each of the channels in the system. Each global image is updated periodically from each of the other channels via cross channel data links. The global images of the local configuration data bases in each channel are separately symmetrized using a voting process to generate a system signal configuration data base which is not written into by any other routine and is available for indicating the status of the system within each channel. Equalization may be imposed on a suspect signal and a number of chances for that signal to heal itself are provided before excluding it from future votes. Reconfiguration is accomplished upon detecting a channel which is deemed invalid. A reset function is provided which permits an externally generated reset signal to permit a previously excluded channel to be reincluded within the system. The updating of global images and/or the symmetrization process may be accomplished at substantially the same time within a synchronized time frame common to all channels.

  7. Improving Active and Passive Avoidance Memories Deficits Due to Permanent Cerebral Ischemia by Pomegranate Seed Extract in Female Rats

    PubMed Central

    Sarkaki, Alireza; Rezaiei, Moslem; Gharib naseri, MohammadKazem; Rafieirad, Maryam

    2013-01-01

    Background: This study aimed to evaluate the effect of two weeks oral administration of pomegranate seed extract (PGSE) on active and passive avoidance memories after permanent bilateral common carotid arteries occlusion (2CCAO) to induce permanent cerebral ischemia in adult female rats. Methods: Seventy adult female Wistar rats (250 ± 20 g) were used. Animals were divided randomly into seven groups with 10 in each: 1) Sham-operated; 2) Ischemic; 3–6) Ischemic received PGSE (100, 200, 400, and 800 mg/2mL/kg, orally) for 14 days; 7) Ischemic received vehicle. In order to create 2CCAO, carotid arteries were ligatured and then cut bilaterally. Active and passive avoidance task were measured using criterion condition responses (CCRs) in Y-maze and step-through latency (STL) in two-way shuttle box in all female rats. Results: Both active and passive avoidance memories were significantly impaired in rats after cerebral hypoxia-ischemia (CHI) (P < 0.001). PGSE treatment significantly improved passive and active memory impairments with 2CCAO (P < 0.05, P < 0.01, and P < 0.001). No toxicity was observed even with high-dose PGSE consumption (800 mg/kg, for 14 days). Conclusion: PGSE exhibits therapeutic potential for avoidance memories, which is most likely related at least in part to its antioxidative and free radical scavenging actions. PMID:23983574

  8. Bilateral injection of fasciculin into the amygdala of rats: effects on two avoidance tasks, acetylcholinesterase activity, and cholinergic muscarinic receptors.

    PubMed

    Quillfeldt, J; Raskovsky, S; Dalmaz, C; Dias, M; Huang, C; Netto, C A; Schneider, F; Izquierdo, I; Medina, J H; Silveira, R

    1990-11-01

    These experiments examined the effects of the bilateral injection of fasciculin-2 (FAS), a natural acetylcholinesterase (AChE) inhibitory peptide, into the amygdala of rats on acquisition and retention of two avoidance behaviors. Intraamygdala injection of FAS (150 ng/amygdala) produced a pronounced and long-lasting inhibition of AChE activity: 85% and 74% on day 2 and day 5, respectively. After 48 hr, FAS-treated animals showed no changes in training or test session performance in a step-down inhibitory avoidance task (training-test interval was 24 hr). In a 2-way shuttle avoidance task, intraamygdala FAS slightly reduced retention test performance without modifying training session scores. Two and five days after FAS injections into the amygdala, the density of muscarinic receptor decreased about 50% as measured by the specific bindings of 3H-quinuclidinyl benzilate and 3H-oxotremorine. No alterations were observed in the apparent dissociation constants. On the other hand, the central-type benzodiazepine receptor population of the amygdala remained unchanged, suggesting that FAS microinjection did not produce damage to neuronal components of these nuclei. In conclusion, the results presented have indicated that a clear-cut and long-lasting inhibition of AChE activity in the amygdala is not accompanied by a facilitation of learning and memory of two different avoidance tasks. Compensation of the increased cholinergic activity by a down-regulation of muscarinic receptors could account for these findings.

  9. Redundancy management of inertial systems.

    NASA Technical Reports Server (NTRS)

    Mckern, R. A.; Musoff, H.

    1973-01-01

    The paper reviews developments in failure detection and isolation techniques applicable to gimballed and strapdown systems. It examines basic redundancy management goals of improved reliability, performance and logistic costs, and explores mechanizations available for both input and output data handling. The meaning of redundant system reliability in terms of available coverage, system MTBF, and mission time is presented and the practical hardware performance limitations of failure detection and isolation techniques are explored. Simulation results are presented illustrating implementation coverages attainable considering IMU performance models and mission detection threshold requirements. The implications of a complete GN&C redundancy management method on inertial techniques are also explored.

  10. Redundant structures at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Guidry, L. I.; Mintz, G. H.

    1980-01-01

    In many structural systems, it is desirable to perform analysis to determine how safe structure is when subjected to "yielding" loads. FRAME1 computer program analyzes, in both plastic and elastic ranges, redundant structures subjected to thermal and mechanical loads.

  11. Verification of redundancy management design

    NASA Technical Reports Server (NTRS)

    Gelderloos, H. C.; Wilson, D. V.

    1978-01-01

    Statistical method checks designs by simulating system operating conditions and adding error factors. Method has potential applicability to commercial and industrial situations where redundancy management system is used to detect and isolate failed components.

  12. Temporal and spatial strategies in an active place avoidance task on Carousel: a study of effects of stability of arena rotation speed in rats.

    PubMed

    Bahník, Štěpán; Stuchlík, Aleš

    2015-01-01

    The active place avoidance task is a dry-arena task used to assess spatial navigation and memory in rodents. In this task, a subject is put on a rotating circular arena and avoids an invisible sector that is stable in relation to the room. Rotation of the arena means that the subject's avoidance must be active, otherwise the subject will be moved in the to-be-avoided sector by the rotation of the arena and a slight electric shock will be administered. The present experiment explored the effect of variable arena rotation speed on the ability to avoid the to-be-avoided sector. Subjects in a group with variable arena rotation speed learned to avoid the sector with the same speed and attained the same avoidance ability as rats in a group with a stable arena rotation speed. Only a slight difference in preferred position within the room was found between the two groups. No difference was found between the two groups in the dark phase, where subjects could not use orientation cues in the room. Only one rat was able to learn the avoidance of the to-be-avoided sector in this phase. The results of the experiment suggest that idiothetic orientation and interval timing are not crucial for learning avoidance of the to-be-avoided sector. However, idiothetic orientation might be sufficient for avoiding the sector in the dark. PMID:26417540

  13. Exaggerated Redundancy Gain in the Split Brain: A Hemispheric Coactivation Account

    ERIC Educational Resources Information Center

    Miller, Jeff

    2004-01-01

    Recent studies of redundancy gain indicate that it is especially large when redundant stimuli are presented to different hemispheres of an individual without a functioning corpus callosum. This suggests the hypothesis that responses to redundant stimuli are speeded partly because both hemispheres are involved in the activation of the response. A…

  14. Active Power Rescheduling for Avoiding Voltage Collapse Using Modified Bare Bones Particle Swarm Optimization

    NASA Astrophysics Data System (ADS)

    Arya, Rajesh; Purey, Pradeep

    2016-06-01

    MW-generation rescheduling is being considered for voltage stability improvement under stressed operating condition. At times it can avoid voltage collapse. This paper describes an algorithm for determination of optimum MW-generation participation pattern for static voltage stability margin enhancement. The optimum search direction has been obtained by employing modified bare born particle swarm optimization technique. Optimum search direction is based on maximization of distance to point of collapse in generation space. Developed algorithm has been implemented on a standard 25 bus test system. Results obtained have been compared with those obtained using standard particle swarm optimization.

  15. Inhibition of long-term memory formation by anti-ependymin antisera after active shock-avoidance learning in goldfish.

    PubMed

    Piront, M L; Schmidt, R

    1988-02-23

    Ependymins are acidic glycoprotein constituents of goldfish brain cytoplasm and extracellular fluid which are known to participate in biochemical reactions of long-term memory formation. In earlier experiments, anti-ependymin antisera were found to cause amnesia when injected into goldfish brain ventricles after the acquisition of a vestibulomotoric training task. To investigate whether they also inhibit memory consolidation after other learning events the anti-ependymin antisera were injected after an active shock-avoidance learning paradigm, as follows: goldfish were trained in a shuttle-box to cross a barrier in order to avoid electric shocks (unconditioned stimulus) applied shortly after a light signal (conditioned stimulus). Anti-ependymin antisera blocked retention of the learned avoidance when injected 0.5, 4.5 or 24 h after acquisition of the new behavior. They had no effect, however, when injected 72 h after learning. Apparently, long-term memory was already consolidated at this point. Antisera injected 0.5 or 72 h prior to training, also did not influence learning or memory. Thirteen percent of the goldfish fled the light stimulus spontaneously. These fish therefore did not experience the unconditioned stimulus and thus were unable to learn the task. When they were treated with the anti-ependymin antisera and tested 3 days later, the spontaneous escape reaction was not affected (active control group). The ability of anti-ependymin antisera to inhibit memory consolidation and their efficacy after administration at specific time intervals are very similar for the active shock-avoidance learning and for the vestibulomotoric training. We conclude that ependymins are not task-specific, but serve a general function in biochemical reactions essential for long-term memory formation.

  16. Training bottlenose dolphins to overcome avoidance of environmental enrichment objects in order to stimulate play activities.

    PubMed

    Neto, Márcia P; Silveira, Miguel; Dos Santos, Manuel E

    2016-05-01

    Enrichment programs may contribute to the quality of life and stress reduction in bottlenose dolphins (Tursiops truncatus) kept in zoos and aquaria. The results of these programs are generally positive in terms of welfare, but the magnitude of their effects may vary greatly between individuals of the same species, especially when the enrichment plans are based on the introduction of manipulative objects. Some animals will interact spontaneously with novel objects, even without food rewards and in the absence of the trainers, while others show no interest or even aversion toward the objects. To determine if formal training can improve these conditions, we measured the effects of an operant conditioning program in the manipulation of objects by dolphins that initially avoided them. This program took place between April and October 2013 at Zoomarine Portugal. Subjects were two female and two male bottlenose dolphins (adults with ages from 17 to 35 years) that after a preliminary analysis showed avoidance or low interest in the manipulation of various toys. The level of interaction with introduced enrichment objects was observed before and after formal training to explore the toys (sixteen 20-min observation sessions per animal "before" and "after training"). In all subjects, an index of interest in object manipulation, in the absence of trainers, increased significantly after the application of the training techniques. The results show that an initial reinforcement program focused on the manipulation of toys may overcome resistance, improving the effects of environmental enrichment plans, and it is a potentially useful strategy to increase the welfare of some captive animals. Zoo Biol. 35:210-215, 2016. © 2016 Wiley Periodicals, Inc.

  17. Training bottlenose dolphins to overcome avoidance of environmental enrichment objects in order to stimulate play activities.

    PubMed

    Neto, Márcia P; Silveira, Miguel; Dos Santos, Manuel E

    2016-05-01

    Enrichment programs may contribute to the quality of life and stress reduction in bottlenose dolphins (Tursiops truncatus) kept in zoos and aquaria. The results of these programs are generally positive in terms of welfare, but the magnitude of their effects may vary greatly between individuals of the same species, especially when the enrichment plans are based on the introduction of manipulative objects. Some animals will interact spontaneously with novel objects, even without food rewards and in the absence of the trainers, while others show no interest or even aversion toward the objects. To determine if formal training can improve these conditions, we measured the effects of an operant conditioning program in the manipulation of objects by dolphins that initially avoided them. This program took place between April and October 2013 at Zoomarine Portugal. Subjects were two female and two male bottlenose dolphins (adults with ages from 17 to 35 years) that after a preliminary analysis showed avoidance or low interest in the manipulation of various toys. The level of interaction with introduced enrichment objects was observed before and after formal training to explore the toys (sixteen 20-min observation sessions per animal "before" and "after training"). In all subjects, an index of interest in object manipulation, in the absence of trainers, increased significantly after the application of the training techniques. The results show that an initial reinforcement program focused on the manipulation of toys may overcome resistance, improving the effects of environmental enrichment plans, and it is a potentially useful strategy to increase the welfare of some captive animals. Zoo Biol. 35:210-215, 2016. © 2016 Wiley Periodicals, Inc. PMID:26969822

  18. Eliciting Student Perceptions regarding Curriculum Redundancy

    ERIC Educational Resources Information Center

    Dalton, Bruce; Wright, Lois

    2004-01-01

    The issue of redundancy has not been well explored in the social work curriculum. The Curriculum Policy Statement requires redundancy in the form of infusion of material across content areas and addresses redundancy vertically between levels of education and year of program. Further, redundancy in the form of repetition with the purpose of…

  19. An approach to modeling a kinematically redundant dual manipulator closed chain system using pseudovelocities

    SciTech Connect

    Unseren, M.A.

    1996-05-01

    The paper discusses the problem of resolving the kinematic redundancy in the closed chain formed when two redundant manipulators mutually lift a rigid body object. The positional degrees of freedom (DOF) in the closed chain are parameterized by a set of independent variables termed pseudovelocities. Due to the redundancy there are more DOF and thus more pseudovelocities than are required to specify the motion of the held object. The additional ``redundant`` pseudovelocities are used to minimize the distance between the vector of unknown joint velocities and a vector of ``corrective`` joint velocities in a Euclidean norm sense. This leads to an optimal solution for the joint velocities as a linear function of the Cartesian object velocities and the corrective velocities. The problem of determining the corrective velocities to avoid collisions of the links with a wall located in the workspace and to avoid joint range limits is illustrated by an example of two redundant planar revolute joint manipulators mutually lifting a rigid object.

  20. Protein synthesis is not required for acquisition, consolidation, and extinction of high foot-shock active avoidance training.

    PubMed

    González-Salinas, Sofía; Medina, Andrea C; Marín-Vignando, Vera; Ruiz-López, Clyo X; Quirarte, Gina L; Prado-Alcalá, Roberto A

    2015-01-01

    Long-term memory of active avoidance in mice is not disturbed by administration of protein synthesis inhibitors (PSIs) when relatively high levels of training are used, whereas a detrimental effect is produced with lower levels of training. PSIs also disrupt extinction of avoidance behaviors in rodents, but it is not clear whether PSIs also affect this form of learning when the behavior to be extinguished was produced by a high level of training. Experiment 1 demonstrated that rats treated with the PSI cycloheximide (CXM) 30 min before training developed normal acquisition after training with either high or low foot-shock stimulation, but that memory consolidation was hindered only after low foot-shock training. Experiment 2 demonstrated that CXM disrupted extinction when administered before the first of a series of extinction sessions when low foot-shock intensity was used during training; in contrast, after training with a higher foot-shock, the PSI treatment only interfered transiently with extinction. These results indicate that acquisition, consolidation, and extinction of active avoidance learning produced by high aversive stimulation are not dependent on protein synthesis and that these processes are governed by mechanisms different from those underlying moderate forms of learning.

  1. An optimal resolved rate law for kinematically redundant manipulators

    NASA Technical Reports Server (NTRS)

    Bourgeois, B. J.

    1987-01-01

    The resolved rate law for a manipulator provides the instantaneous joint rates required to satisfy a given instantaneous hand motion. When the joint space has more degrees of freedom than the task space, the manipulator is kinematically redundant and the kinematic rate equations are underdetermined. These equations can be locally optimized, but the resulting pseudo-inverse solution has been found to cause large joint rates in some cases. A weighting matrix in the locally optimized (pseudo-inverse) solution is dynamically adjusted to control the joint motion as desired. Joint reach limit avoidance is demonstrated in a kinematically redundant planar arm model. The treatment is applicable to redundant manipulators with any number of revolute joints and to non-planar manipulators.

  2. An optimal resolved rate law for kindematically redundant manipulators

    NASA Technical Reports Server (NTRS)

    Bourgeois, B. J.

    1987-01-01

    The resolved rate law for a manipulator provides the instantaneous joint rates required to satisfy a given instantaneous hand motion. When the joint space has more degrees of freedom than the task space, the manipulator is kinematically redundant and the kinematic rate equations are underdetermined. These equations can be locally optimized, but the resulting pseudo-inverse solution was found to cause large joint rates in some case. A weighting matrix in the locally optimized (pseudo-inverse) solution is dynamically adjusted to control the joint motion as desired. Joint reach limit avoidance is demonstrated in a kinematically redundant planar arm model. The treatment is applicable to redundant manipulators with any number of revolute joints and to nonplanar manipulators.

  3. Are fear-avoidance beliefs in low back pain patients a risk factor for low physical activity or vice versa? A cross-lagged panel analysis

    PubMed Central

    Leonhardt, Corinna; Lehr, Dirk; Chenot, Jean-François; Keller, Stefan; Luckmann, Judith; Basler, Heinz-Dieter; Baum, Erika; Donner-Banzhoff, Norbert; Pfingsten, Michael; Hildebrandt, Jan; Kochen, Michael M.; Becker, Annette

    2009-01-01

    Objective: The assumption that low back pain (LBP) patients suffer from “disuse” as a consequence of high fear-avoidance beliefs is currently under debate. A secondary analysis served to investigate whether fear-avoidance beliefs are associated cross-sectionally and longitudinally with the physical activity level (PAL) in LBP patients. Methods: A total of 787 individuals (57% acute and 43% chronic LBP) were followed up over a period of one year with measurements of fear-avoidance beliefs and physical activity level. Fear-avoidance beliefs concerning physical activity were measured by the physical-activity subscale of the FABQ (Fear-Avoidance Beliefs Questionnaire), the physical activity level was assessed in weighted metabolic equivalents (MET) hours/week with a German self-report questionnaire. Data were investigated by structural equation modelling in a cross-lagged panel design for the whole sample and separately for acute and chronic LBP. Results: The acute and chronic sub sample increased their total physical activity level significantly after one year. The structural equation modelling results did not support the disuse-aspect inherent in the fear-avoidance belief model. Cross-lagged path coefficients were low (.04 and .05 respectively) and, therefore, did not allow to predict final physical activity by initial fear-avoidance beliefs or vice versa. Discussion: Consequently, due to missing links between fear-avoidance beliefs and physical activity in a longitudinal design, the assumptions of the fear-avoidance belief model have to be questioned. These findings are in line with other investigations published recently. Most probably, “fear-avoidance belief” represents a cognitive scheme that does not limit activity per se, but only is directed to the avoidance of specific movements. PMID:19742047

  4. On controlling robots with redundancy

    NASA Technical Reports Server (NTRS)

    Colbaugh, R.; Glass, K.

    1991-01-01

    An adaptive position control scheme for manipulators possessing either kinematic or actuator redundancy is presented. The controller is developed by considering the end-effector position control problem and redundancy resolution problem separately. The end-effector position control problem is solved by using an adaptive scheme to generate the Cartesian-space control input required to track the desired end-effector position trajectory; this control problem is nonredundant even for redundant robots. The Cartesian-space position controller is derived using a model reference adaptive control (MRAC) approach, and does not require knowledge of the complex robot dynamic model or parameter values for the robot or the payload. As a result, the scheme is applicable to both open-chain and closed-chain robots, and is computationally efficient for on-line implementations.

  5. Redundant computing for exascale systems.

    SciTech Connect

    Stearley, Jon R.; Riesen, Rolf E.; Laros, James H., III; Ferreira, Kurt Brian; Pedretti, Kevin Thomas Tauke; Oldfield, Ron A.; Brightwell, Ronald Brian

    2010-12-01

    Exascale systems will have hundred thousands of compute nodes and millions of components which increases the likelihood of faults. Today, applications use checkpoint/restart to recover from these faults. Even under ideal conditions, applications running on more than 50,000 nodes will spend more than half of their total running time saving checkpoints, restarting, and redoing work that was lost. Redundant computing is a method that allows an application to continue working even when failures occur. Instead of each failure causing an application interrupt, multiple failures can be absorbed by the application until redundancy is exhausted. In this paper we present a method to analyze the benefits of redundant computing, present simulation results of the cost, and compare it to other proposed methods for fault resilience.

  6. Redundant variables and Granger causality

    NASA Astrophysics Data System (ADS)

    Angelini, L.; de Tommaso, M.; Marinazzo, D.; Nitti, L.; Pellicoro, M.; Stramaglia, S.

    2010-03-01

    We discuss the use of multivariate Granger causality in presence of redundant variables: the application of the standard analysis, in this case, leads to under estimation of causalities. Using the un-normalized version of the causality index, we quantitatively develop the notions of redundancy and synergy in the frame of causality and propose two approaches to group redundant variables: (i) for a given target, the remaining variables are grouped so as to maximize the total causality and (ii) the whole set of variables is partitioned to maximize the sum of the causalities between subsets. We show the application to a real neurological experiment, aiming to a deeper understanding of the physiological basis of abnormal neuronal oscillations in the migraine brain. The outcome by our approach reveals the change in the informational pattern due to repetitive transcranial magnetic stimulations.

  7. Redundant variables and Granger causality.

    PubMed

    Angelini, L; de Tommaso, M; Marinazzo, D; Nitti, L; Pellicoro, M; Stramaglia, S

    2010-03-01

    We discuss the use of multivariate Granger causality in presence of redundant variables: the application of the standard analysis, in this case, leads to under estimation of causalities. Using the un-normalized version of the causality index, we quantitatively develop the notions of redundancy and synergy in the frame of causality and propose two approaches to group redundant variables: (i) for a given target, the remaining variables are grouped so as to maximize the total causality and (ii) the whole set of variables is partitioned to maximize the sum of the causalities between subsets. We show the application to a real neurological experiment, aiming to a deeper understanding of the physiological basis of abnormal neuronal oscillations in the migraine brain. The outcome by our approach reveals the change in the informational pattern due to repetitive transcranial magnetic stimulations.

  8. Avoiding Ticks

    MedlinePlus

    ... Avoiding ticks On people On pets In the yard Removing a tick Symptoms of tickborne illness Geographic ... ticks on your pets Preventing ticks in the yard File Formats Help: How do I view different ...

  9. Constrained Stochastic Extended Redundancy Analysis.

    PubMed

    DeSarbo, Wayne S; Hwang, Heungsun; Stadler Blank, Ashley; Kappe, Eelco

    2015-06-01

    We devise a new statistical methodology called constrained stochastic extended redundancy analysis (CSERA) to examine the comparative impact of various conceptual factors, or drivers, as well as the specific predictor variables that contribute to each driver on designated dependent variable(s). The technical details of the proposed methodology, the maximum likelihood estimation algorithm, and model selection heuristics are discussed. A sports marketing consumer psychology application is provided in a Major League Baseball (MLB) context where the effects of six conceptual drivers of game attendance and their defining predictor variables are estimated. Results compare favorably to those obtained using traditional extended redundancy analysis (ERA). PMID:24327066

  10. Constrained Stochastic Extended Redundancy Analysis.

    PubMed

    DeSarbo, Wayne S; Hwang, Heungsun; Stadler Blank, Ashley; Kappe, Eelco

    2015-06-01

    We devise a new statistical methodology called constrained stochastic extended redundancy analysis (CSERA) to examine the comparative impact of various conceptual factors, or drivers, as well as the specific predictor variables that contribute to each driver on designated dependent variable(s). The technical details of the proposed methodology, the maximum likelihood estimation algorithm, and model selection heuristics are discussed. A sports marketing consumer psychology application is provided in a Major League Baseball (MLB) context where the effects of six conceptual drivers of game attendance and their defining predictor variables are estimated. Results compare favorably to those obtained using traditional extended redundancy analysis (ERA).

  11. Engager and Avoider Behaviour in Types of Activities Performed by Out-of-Class Learning Groups

    ERIC Educational Resources Information Center

    Yan, Louisa; Kember, David

    2004-01-01

    This study examines the out-of-class learning activities undertaken, at the students' volition, by groups of students. Data were gathered through 57 individual and 15 focus group interviews with university students in Hong Kong. Group activities reported included: copying, sharing material, consulting peers, consulting teachers, studying and…

  12. Amplification, Redundancy, and Quantum Chernoff Information

    NASA Astrophysics Data System (ADS)

    Zwolak, Michael; Riedel, C. Jess; Zurek, Wojciech H.

    2014-04-01

    Amplification was regarded, since the early days of quantum theory, as a mysterious ingredient that endows quantum microstates with macroscopic consequences, key to the "collapse of the wave packet," and a way to avoid embarrassing problems exemplified by Schrödinger's cat. Such a bridge between the quantum microworld and the classical world of our experience was postulated ad hoc in the Copenhagen interpretation. Quantum Darwinism views amplification as replication, in many copies, of the information about quantum states. We show that such amplification is a natural consequence of a broad class of models of decoherence, including the photon environment we use to obtain most of our information. This leads to objective reality via the presence of robust and widely accessible records of selected quantum states. The resulting redundancy (the number of copies deposited in the environment) follows from the quantum Chernoff information that quantifies the information transmitted by a typical elementary subsystem of the environment.

  13. Amplification, redundancy, and quantum Chernoff information.

    PubMed

    Zwolak, Michael; Riedel, C Jess; Zurek, Wojciech H

    2014-04-11

    Amplification was regarded, since the early days of quantum theory, as a mysterious ingredient that endows quantum microstates with macroscopic consequences, key to the "collapse of the wave packet," and a way to avoid embarrassing problems exemplified by Schrödinger's cat. Such a bridge between the quantum microworld and the classical world of our experience was postulated ad hoc in the Copenhagen interpretation. Quantum Darwinism views amplification as replication, in many copies, of the information about quantum states. We show that such amplification is a natural consequence of a broad class of models of decoherence, including the photon environment we use to obtain most of our information. This leads to objective reality via the presence of robust and widely accessible records of selected quantum states. The resulting redundancy (the number of copies deposited in the environment) follows from the quantum Chernoff information that quantifies the information transmitted by a typical elementary subsystem of the environment.

  14. Post-traumatic stress avoidance is attenuated by corticosterone and associated with brain levels of steroid receptor co-activator-1 in rats.

    PubMed

    Whitaker, Annie M; Farooq, Muhammad A; Edwards, Scott; Gilpin, Nicholas W

    2016-01-01

    Individuals with post-traumatic stress disorder (PTSD) avoid trauma-related stimuli and exhibit blunted hypothalamic-pituitary-adrenal (HPA) axis activation at the time of stress. Our rodent model of stress mimics the avoidance symptom cluster of PTSD. Rats are classified as "Avoiders" or "Non-Avoiders" post-stress based on the avoidance of a predator-odor paired context. Previously, we found Avoiders exhibit an attenuated HPA stress response to predator odor. We hypothesized that corticosterone administration before stress would reduce the magnitude and incidence of stress-paired context avoidance. Furthermore, we also predicted that Avoiders would exhibit altered expression of glucocorticoid receptor (GR) signaling machinery elements, including steroid receptor co-activator (SRC)-1. Male Wistar rats (n = 16) were pretreated with corticosterone (25 mg/kg) or saline and exposed to predator-odor stress paired with a context and tested for avoidance 24 h later. A second group of corticosterone-naïve rats (n = 24) were stressed (or not), indexed for avoidance 24 h later, and killed 48 h post-odor exposure to measure phosphorylated GR, FKBP51 and SRC-1 levels in the paraventricular nucleus (PVN), central amygdala (CeA) and ventral hippocampus (VH), all brain sites that highly express GRs and regulate HPA function. Corticosterone pretreatment reduced the magnitude and incidence of avoidance. In Avoiders, predator-odor exposure led to lower SRC-1 expression in the PVN and CeA, and higher SRC-1 expression in the VH. SRC-1 expression in PVN, CeA and VH was predicted by prior avoidance behavior. Hence, a blunted HPA stress response may contribute to stress-induced neuroadaptations in central SRC-1 levels and behavioral dysfunction in Avoider rats.

  15. Habituation of dairy heifers to milking routine-Effects on human avoidance distance, behavior, and cardiac activity during milking.

    PubMed

    Kutzer, T; Steilen, M; Gygax, L; Wechsler, B

    2015-08-01

    The onset of lactation marks a significant turning point in a heifer's life, and prior experience with the milking routine could have positive effects on animal welfare and productivity. The objectives of this multifarm (n=5) study were to investigate (1) whether prelactation training sessions affected behavior during milking, cardiac activity, human avoidance distance, and milk yield, and (2) whether these responses would be modified by the heifer's initial level of fear of humans. Trained heifers (TH, n=30) experienced the routine in the milking parlor on at least 10 d prepartum, whereas untrained heifers (UH, n=29) entered the parlor for the first time after calving. Behavior and cardiac activity were recorded on d 1 and 7 after calving, and an avoidance test was carried out on the day of integration into the dairy herd as well as on d 1, 7, and 28 postpartum. Each animal's initial level of fear of humans was classified as high or low based on the first human avoidance distance measured toward an unknown person. Results showed that TH showed less stepping and kicking during the udder preparation phase in the parlor and UH had higher probabilities to put their ears flat on the head, clamp their tail between the hind legs, and have their eyes wide open throughout the different phases in the milking parlor. Heart rate decreased from d 1 to 7, increased from before to during and to after milking and was slightly elevated in TH compared with UH. Milk yield did not differ between TH and UH. Human avoidance distance was not influenced by training, but distance decreased in heifers with a high initial level of fear of humans across repetitions of the test, whereas heifers with a low initial level of fear of humans had generally short avoidance distances. However, initial level of fear of humans neither determined behavior and heart rate during milking nor milk yield of TH and UH. The results indicate that the training regimen applied in the present study habituated

  16. Redundant actuator development program. [for flight control

    NASA Technical Reports Server (NTRS)

    Chenoweth, C. C.; Fain, D. M.; Svensson, C. I.

    1975-01-01

    Two concepts of redundant secondary actuator mechanization, applicable to future advanced flight control systems, were studied to quantitatively assess their design applicability to an AST. The two actuator concepts, a four-channel, force summed system and a three-channel, active/standby system have been developed and evaluated through analysis, analog computer simulation, and piloted motion simulation. The quantitative comparison of the two concepts indicates that the force summed concept better meet performance requirements, although the active/standby is superior in other respects. Both concepts are viable candidates for advanced control application dependent on the specific performance requirements.

  17. [Influence of chronic melipramine administration abolition on locomotion and defensive conditioned reflexes in passive and active avoidance in rats].

    PubMed

    Orlova, N V; Folomkina, A A; Koshtoiants, O Kh; Bazian, A S

    2005-01-01

    The chronic (21 days duration) administration of tricyclic antidepressant melipramine of Wistar rats strain (15 mg/kg daily, intraperitoneally) evoked weight loss of animals. The 7 days after melipramine abolition its sedative effect was observed in the "open field" test by decrease of locomotion and the number of boles. The 7 and 14 days after melipramine abolition the difference between control and melipramine treated animals in passive and active avoidance learning and memory not found. The experimental results comparison with the literature data show, that chronic melipramine administration of intact animals evokes a sedative state. This conclusion does not contradict to idea of punishment function of brain serotoninergic system. PMID:15828425

  18. Molecular pathways activation in coronary artery bypass surgery: which role for pump avoidance?

    PubMed

    Parolari, Alessandro; Poggio, Paolo; Myasoedova, Veronika; Songia, Paola; Pilozzi, Alberto; Alamanni, Francesco; Tremoli, Elena

    2016-01-01

    In this study, we review current knowledge regarding molecular pathways activation and their possible mechanisms in the perioperative period of coronary artery bypass surgery (CABG). We also highlight the role of off-pump CABG as a possible way to better understand these biological changes.We show that, after both on-pump and off-pump CABG, there is a marked and protracted activation of several molecular pathways indicating increased inflammatory status, haemostasis activation, as well as increased oxidative stress and unfavourable endothelial milieu. These changes persist for days and even weeks after surgery. Interestingly, a relatively limited number of these pathways show a more pronounced activation in case of cardiopulmonary bypass use, and these markers are mainly associated with oxidative stress activation; on the contrary, the vast majority of the pathways has a similar course both in on and off-pump procedures. Surgical stress accounts for more protracted and marked molecular pathway perturbations overall, being the effect of cardiopulmonary, if any, limited to the very early hours after surgery. The near future of the translational research in coronary bypass surgery is to develop therapeutic strategies aimed at reducing this response, that is largely unrelated to cardiopulmonary bypass use, in order to reduce perioperative complications and to speed up patients' recovery.

  19. On the participation of hippocampal p38 mitogen-activated protein kinase in extinction and reacquisition of inhibitory avoidance memory.

    PubMed

    Rossato, J I; Bevilaqua, L R M; Lima, R H; Medina, J H; Izquierdo, I; Cammarota, M

    2006-11-17

    Inhibitory avoidance (IA) learning relies on the formation of an association between stepping down from a platform present in a certain context (conditioned stimulus; CS) with an aversive unconditioned stimulus (US; i.e. a footshock). A single CS-US pairing establishes a robust long-term memory expressed as an increase in step-down latency at testing. However, repeated retrieval of the avoidance response in the absence of the US induces extinction of IA memory. That is, recurring presentation of the CS alone results in a new learning indicating that the CS no longer predicts the US. Although the signaling pathways involved in the consolidation of IA and other fear-motivated memories have been profusely studied, little is known about the molecular requirements of fear memory extinction. Here we report that, as happens with its consolidation, extinction of IA long-term memory requires activity of the p38 subfamily of mitogen-activated protein kinases (MAPK) in the CA1 region of the dorsal hippocampus. Moreover, we found that inhibition of hippocampal p38MAPK blocked memory reacquisition after extinction without affecting either the increase in IA memory retention induced by a second training session or animal's locomotor/exploratory activity and anxiety state.

  20. Detecting short-term responses to weekend recreation activity: desert bighorn sheep avoidance of hiking trails

    USGS Publications Warehouse

    Longshore, Kathleen; Lowrey, Chris; Thompson, Daniel B.

    2013-01-01

    To study potential effects of recreation activity on habitat use of desert bighorn sheep (Ovis canadensis nelsoni), we placed Global Positioning System collars on 10 female bighorn sheep within the Wonderland of Rocks–Queen Mountain region of Joshua Tree National Park (JOTR), California, USA, from 2002 to 2004. Recreation use was highest from March to April and during weekends throughout the year. Daily use of recreation trails was highest during midday. By comparing habitat use (slope, ruggedness, distance to water, and distance to recreation trails) of female bighorn sheep on weekdays versus weekends, we were able to detect short-term shifts in behavior in response to recreation. In a logistic regression of bighorn sheep locations versus random locations for March and April, female locations at midday (1200 hours) were significantly more distant from recreation trails on weekends compared with weekdays. Our results indicate that within this region of JOTR, moderate to high levels of human recreation activity may temporarily exclude bighorn females from their preferred habitat. However, the relative proximity of females to recreation trails during the weekdays before and after such habitat shifts indicates that these anthropogenic impacts were short-lived. Our results have implications for management of wildlife on public lands where the co-existence of wildlife and recreational use is a major goal.

  1. Functional Redundancy Instead of Species Redundancy Determines Community Stability in a Typical Steppe of Inner Mongolia

    PubMed Central

    Kang, Saruul; Ma, Wenjing; Li, Frank Yonghong; Zhang, Qing; Niu, Jianming; Ding, Yong; Han, Fang; Sun, Xiaoli

    2015-01-01

    Background The redundancy hypothesis predicts that the species redundancy in a plant community enhances community stability. However, numerous studies in recent years questioned the positive correlation between redundancy and stability. Methodology We explored the relationship between the species redundancy, functional redundancy and community stability in typical steppe grassland in Northern China by sampling grassland vegetation along a gradient of resource availability caused by micro-topography. We aimed to test whether community redundancy enhanced community stability, and to quantify the relative importance of species redundancy and functional redundancy in maintaining community stability. Results Our results showed that the spatial stability of plant community production increases with increased supply of soil resources, and the functional redundancy instead of species diversity or species redundancy is correlated with the community stability. Our results supported the redundancy hypothesis and have implications for sustainable grassland management. PMID:26699133

  2. Shade Avoidance

    PubMed Central

    Casal, Jorge J.

    2012-01-01

    The presence of neighboring vegetation modifies the light environment experienced by plants, generating signals that are perceived by phytochromes and cryptochromes. These signals cause large changes in plant body form and function, including enhanced growth of the hypocotyl and petioles, a more erect position of the leaves and early flowering in Arabidopsis thaliana. Collectively, these so-called shade-avoidance responses tend to reduce the degree of current or future shade by neighbors. Shade light signals increase the abundance of PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and PIF5 proteins, promote the synthesis and redirection of auxin, favor the degradation of DELLA proteins and increase the expression of auxin, gibberellins and brassinosteroid-promoted genes, among other events downstream the photoreceptors. Selectively disrupting these events by genetic or pharmacological approaches affects shade-avoidance responses with an intensity that depends on the developmental context and the environment. Shade-avoidance responses provide a model to investigate the signaling networks used by plants to take advantage of the cues provided by the environment to adjust to the challenges imposed by the environment itself. PMID:22582029

  3. RelB activation in anti-inflammatory decidual endothelial cells: a master plan to avoid pregnancy failure?

    PubMed

    Masat, Elisa; Gasparini, Chiara; Agostinis, Chiara; Bossi, Fleur; Radillo, Oriano; De Seta, Francesco; Tamassia, Nicola; Cassatella, Marco A; Bulla, Roberta

    2015-01-01

    It is known that excessive inflammation at fetal-maternal interface is a key contributor in a compromised pregnancy. Female genital tract is constantly in contact with microorganisms and several strategies must be adopted to avoid pregnancy failure. Decidual endothelial cells (DECs) lining decidual microvascular vessels are the first cells that interact with pro-inflammatory stimuli released into the environment by microorganisms derived from gestational tissues or systemic circulation. Here, we show that DECs are hypo-responsive to LPS stimulation in terms of IL-6, CXCL8 and CCL2 production. Our results demonstrate that DECs express low levels of TLR4 and are characterized by a strong constitutive activation of the non-canonical NF-κB pathway and a low responsiveness of the canonical pathway to LPS. In conclusion, DECs show a unique hypo-responsive phenotype to the pro-inflammatory stimulus LPS in order to control the inflammatory response at feto-maternal interface. PMID:26463648

  4. When Threat Is Near, Get Out of Here: Dynamics of Defensive Behavior During Freezing and Active Avoidance.

    PubMed

    Löw, Andreas; Weymar, Mathias; Hamm, Alfons O

    2015-11-01

    When detecting a threat, humans and other animals engage in defensive behaviors and supporting physiological adjustments that vary with threat imminence and potential response options. In the present study, we shed light on the dynamics of defensive behaviors and associated physiological adjustments in humans using multiple psychophysiological and brain measures. When participants were exposed to a dynamically approaching, uncontrollable threat, attentive freezing was augmented, as indicated by an increase in skin conductance, fear bradycardia, and potentiation of the startle reflex. In contrast, when participants had the opportunity to actively avoid the approaching threat, attention switched to response preparation, as indicated by an inhibition of the startle magnitude and by a sharp drop of the probe-elicited P3 component of the evoked brain potentials. These new findings on the dynamics of defensive behaviors form an important intersection between animal and human research and have important implications for understanding fear and anxiety-related disorders.

  5. Normal inhibitory avoidance learning and anxiety, but increased locomotor activity in mice devoid of PrP(C).

    PubMed

    Roesler, R; Walz, R; Quevedo, J; de-Paris, F; Zanata, S M; Graner, E; Izquierdo, I; Martins, V R; Brentani, R R

    1999-08-25

    Prions are the causative agents of transmissible spongiform encephalopathies. The transmissible agent (PrP(Sc)) is an abnormal form of PrP(C), a normal neuronal protein. The physiological role of PrP(C) remains unclear. In the present report, we evaluated behavioral parameters in Prnp(0/0) mice devoid of PrP(C). Prnp(0/0) mice showed normal short- and long-term retention of a step-down inhibitory avoidance task and normal behavior in an elevated plus maze test of anxiety. During a 5-min exploration of an open field, Prnp(0/0) mice showed normal number of rearings, defecation, and latency to initiate locomotion, but a significant increase in the number of crossings. The results suggest that Prnp(0/0) mice show normal fear-motivated memory, anxiety and exploratory behavior, and a slight increase in locomotor activity during exploration of a novel environment.

  6. Caenorhabditis elegans glutamylating enzymes function redundantly in male mating

    PubMed Central

    Chawla, Daniel G.; Shah, Ruchi V.; Barth, Zachary K.; Lee, Jessica D.; Badecker, Katherine E.; Naik, Anar; Brewster, Megan M.; Salmon, Timothy P.

    2016-01-01

    ABSTRACT Microtubule glutamylation is an important modulator of microtubule function and has been implicated in the regulation of centriole stability, neuronal outgrowth and cilia motility. Glutamylation of the microtubules is catalyzed by a family of tubulin tyrosine ligase-like (TTLL) enzymes. Analysis of individual TTLL enzymes has led to an understanding of their specific functions, but how activities of the TTLL enzymes are coordinated to spatially and temporally regulate glutamylation remains relatively unexplored. We have undertaken an analysis of the glutamylating TTLL enzymes in C. elegans. We find that although all five TTLL enzymes are expressed in the embryo and adult worm, loss of individual enzymes does not perturb microtubule function in embryonic cell divisions. Moreover, normal dye-filling, osmotic avoidance and male mating behavior indicate the presence of functional amphid cilia and male-specific neurons. A ttll-4(tm3310); ttll-11(tm4059); ttll-5(tm3360) triple mutant, however, shows reduced male mating efficiency due to a defect in the response step, suggesting that these three enzymes function redundantly, and that glutamylation is required for proper function of the male-specific neurons. PMID:27635036

  7. Caenorhabditis elegans glutamylating enzymes function redundantly in male mating.

    PubMed

    Chawla, Daniel G; Shah, Ruchi V; Barth, Zachary K; Lee, Jessica D; Badecker, Katherine E; Naik, Anar; Brewster, Megan M; Salmon, Timothy P; Peel, Nina

    2016-01-01

    Microtubule glutamylation is an important modulator of microtubule function and has been implicated in the regulation of centriole stability, neuronal outgrowth and cilia motility. Glutamylation of the microtubules is catalyzed by a family of tubulin tyrosine ligase-like (TTLL) enzymes. Analysis of individual TTLL enzymes has led to an understanding of their specific functions, but how activities of the TTLL enzymes are coordinated to spatially and temporally regulate glutamylation remains relatively unexplored. We have undertaken an analysis of the glutamylating TTLL enzymes in C. elegans We find that although all five TTLL enzymes are expressed in the embryo and adult worm, loss of individual enzymes does not perturb microtubule function in embryonic cell divisions. Moreover, normal dye-filling, osmotic avoidance and male mating behavior indicate the presence of functional amphid cilia and male-specific neurons. A ttll-4(tm3310); ttll-11(tm4059); ttll-5(tm3360) triple mutant, however, shows reduced male mating efficiency due to a defect in the response step, suggesting that these three enzymes function redundantly, and that glutamylation is required for proper function of the male-specific neurons. PMID:27635036

  8. Caenorhabditis elegans glutamylating enzymes function redundantly in male mating.

    PubMed

    Chawla, Daniel G; Shah, Ruchi V; Barth, Zachary K; Lee, Jessica D; Badecker, Katherine E; Naik, Anar; Brewster, Megan M; Salmon, Timothy P; Peel, Nina

    2016-09-15

    Microtubule glutamylation is an important modulator of microtubule function and has been implicated in the regulation of centriole stability, neuronal outgrowth and cilia motility. Glutamylation of the microtubules is catalyzed by a family of tubulin tyrosine ligase-like (TTLL) enzymes. Analysis of individual TTLL enzymes has led to an understanding of their specific functions, but how activities of the TTLL enzymes are coordinated to spatially and temporally regulate glutamylation remains relatively unexplored. We have undertaken an analysis of the glutamylating TTLL enzymes in C. elegans We find that although all five TTLL enzymes are expressed in the embryo and adult worm, loss of individual enzymes does not perturb microtubule function in embryonic cell divisions. Moreover, normal dye-filling, osmotic avoidance and male mating behavior indicate the presence of functional amphid cilia and male-specific neurons. A ttll-4(tm3310); ttll-11(tm4059); ttll-5(tm3360) triple mutant, however, shows reduced male mating efficiency due to a defect in the response step, suggesting that these three enzymes function redundantly, and that glutamylation is required for proper function of the male-specific neurons.

  9. Plasma Hypoxanthine-Guanine Phosphoribosyl Transferase Activity in Bottlenose Dolphins Contributes to Avoiding Accumulation of Non-recyclable Purines

    PubMed Central

    López-Cruz, Roberto I.; Crocker, Daniel E.; Gaxiola-Robles, Ramón; Bernal, Jaime A.; Real-Valle, Roberto A.; Lugo-Lugo, Orlando; Zenteno-Savín, Tania

    2016-01-01

    Marine mammals are exposed to ischemia/reperfusion and hypoxia/reoxygenation during diving. During oxygen deprivation, adenosine triphosphate (ATP) breakdown implies purine metabolite accumulation, which in humans is associated with pathological conditions. Purine recycling in seals increases in response to prolonged fasting and ischemia. Concentrations of metabolites and activities of key enzymes in purine metabolism were examined in plasma and red blood cells from bottlenose dolphins (Tursiops truncatus) and humans. Hypoxanthine and inosine monophosphate concentrations were higher in plasma from dolphins than humans. Plasma hypoxanthine-guanine phosphoribosyl transferase (HGPRT) activity in dolphins suggests an elevated purine recycling rate, and a mechanism for avoiding accumulation of non-recyclable purines (xanthine and uric acid). Red blood cell concentrations of hypoxanthine, adenosine diphosphate, ATP and guanosine triphosphate were lower in dolphins than in humans; adenosine monophosphate and nicotinamide adenine dinucleotide concentrations were higher in dolphins. HGPRT activity in red blood cells was higher in humans than in dolphins. The lower concentrations of purine catabolism and recycling by-products in plasma from dolphins could be beneficial in providing substrates for recovery of ATP depleted during diving or vigorous swimming. These results suggest that purine salvage in dolphins could be a mechanism for delivering nucleotide precursors to tissues with high ATP and guanosine triphosphate requirements. PMID:27375492

  10. Plasma Hypoxanthine-Guanine Phosphoribosyl Transferase Activity in Bottlenose Dolphins Contributes to Avoiding Accumulation of Non-recyclable Purines.

    PubMed

    López-Cruz, Roberto I; Crocker, Daniel E; Gaxiola-Robles, Ramón; Bernal, Jaime A; Real-Valle, Roberto A; Lugo-Lugo, Orlando; Zenteno-Savín, Tania

    2016-01-01

    Marine mammals are exposed to ischemia/reperfusion and hypoxia/reoxygenation during diving. During oxygen deprivation, adenosine triphosphate (ATP) breakdown implies purine metabolite accumulation, which in humans is associated with pathological conditions. Purine recycling in seals increases in response to prolonged fasting and ischemia. Concentrations of metabolites and activities of key enzymes in purine metabolism were examined in plasma and red blood cells from bottlenose dolphins (Tursiops truncatus) and humans. Hypoxanthine and inosine monophosphate concentrations were higher in plasma from dolphins than humans. Plasma hypoxanthine-guanine phosphoribosyl transferase (HGPRT) activity in dolphins suggests an elevated purine recycling rate, and a mechanism for avoiding accumulation of non-recyclable purines (xanthine and uric acid). Red blood cell concentrations of hypoxanthine, adenosine diphosphate, ATP and guanosine triphosphate were lower in dolphins than in humans; adenosine monophosphate and nicotinamide adenine dinucleotide concentrations were higher in dolphins. HGPRT activity in red blood cells was higher in humans than in dolphins. The lower concentrations of purine catabolism and recycling by-products in plasma from dolphins could be beneficial in providing substrates for recovery of ATP depleted during diving or vigorous swimming. These results suggest that purine salvage in dolphins could be a mechanism for delivering nucleotide precursors to tissues with high ATP and guanosine triphosphate requirements.

  11. Plasma Hypoxanthine-Guanine Phosphoribosyl Transferase Activity in Bottlenose Dolphins Contributes to Avoiding Accumulation of Non-recyclable Purines.

    PubMed

    López-Cruz, Roberto I; Crocker, Daniel E; Gaxiola-Robles, Ramón; Bernal, Jaime A; Real-Valle, Roberto A; Lugo-Lugo, Orlando; Zenteno-Savín, Tania

    2016-01-01

    Marine mammals are exposed to ischemia/reperfusion and hypoxia/reoxygenation during diving. During oxygen deprivation, adenosine triphosphate (ATP) breakdown implies purine metabolite accumulation, which in humans is associated with pathological conditions. Purine recycling in seals increases in response to prolonged fasting and ischemia. Concentrations of metabolites and activities of key enzymes in purine metabolism were examined in plasma and red blood cells from bottlenose dolphins (Tursiops truncatus) and humans. Hypoxanthine and inosine monophosphate concentrations were higher in plasma from dolphins than humans. Plasma hypoxanthine-guanine phosphoribosyl transferase (HGPRT) activity in dolphins suggests an elevated purine recycling rate, and a mechanism for avoiding accumulation of non-recyclable purines (xanthine and uric acid). Red blood cell concentrations of hypoxanthine, adenosine diphosphate, ATP and guanosine triphosphate were lower in dolphins than in humans; adenosine monophosphate and nicotinamide adenine dinucleotide concentrations were higher in dolphins. HGPRT activity in red blood cells was higher in humans than in dolphins. The lower concentrations of purine catabolism and recycling by-products in plasma from dolphins could be beneficial in providing substrates for recovery of ATP depleted during diving or vigorous swimming. These results suggest that purine salvage in dolphins could be a mechanism for delivering nucleotide precursors to tissues with high ATP and guanosine triphosphate requirements. PMID:27375492

  12. Analytic redundancy management for large flexible structures

    NASA Technical Reports Server (NTRS)

    Shenhar, J.; Montgomery, R. C.

    1992-01-01

    An analytic redundancy management approach for on-line component failure detection is described and illustrated using a simulation of the NASA Langley Spacecaft Control Laboratory Experiment (SCOLE) research facility. The SCOLE experimental apparatus simulated is a functional model of the Space Shuttle with a large, flexible, offset-feed antenna cantilevered from the payload bay. This approach uses a single, active, Kalman filter selected from a bank of filters, each element of which was previously designed to accommodate a specific failure condition. The residuals of this active filter are processed through a sequential probability ratio test (SPRT) filter to identify the failure state of the system and, hence, closing the failure accommodation loop, to select the active filter. Results are presented that illustrate the ability of the system to detect and recover from failures introduced in the angular rate and linear acceleration sensors on the SCOLE facility.

  13. α1-Adrenoceptors in the hippocampal dentate gyrus involved in learning-dependent long-term potentiation during active-avoidance learning in rats.

    PubMed

    Lv, Jing; Zhan, Su-Yang; Li, Guang-Xie; Wang, Dan; Li, Ying-Shun; Jin, Qing-Hua

    2016-11-01

    The hippocampus is the key structure for learning and memory in mammals and long-term potentiation (LTP) is an important cellular mechanism responsible for learning and memory. The influences of norepinephrine (NE) on the modulation of learning and memory, as well as LTP, through β-adrenoceptors are well documented, whereas the role of α1-adrenoceptors in learning-dependent LTP is not yet clear. In the present study, we measured extracellular concentrations of NE in the hippocampal dentate gyrus (DG) region using an in-vivo brain microdialysis and high-performance liquid chromatography techniques during the acquisition and extinction of active-avoidance behavior in freely moving conscious rats. Next, the effects of prazosin (an antagonist of α1-adrenoceptor) and phenylephrine (an agonist of the α1-adrenoceptor) on amplitudes of field excitatory postsynaptic potential were measured in the DG region during the active-avoidance behavior. Our results showed that the extracellular concentration of NE in the DG was significantly increased during the acquisition of active-avoidance behavior and gradually returned to the baseline level following extinction training. A local microinjection of prazosin into the DG significantly accelerated the acquisition of the active-avoidance behavior, whereas a local microinjection of phenylephrine retarded the acquisition of the active-avoidance behavior. Furthermore, in all groups, the changes in field excitatory postsynaptic potential amplitude were accompanied by corresponding changes in active-avoidance behavior. Our results suggest that NE activation of α1-adrenoceptors in the hippocampal DG inhibits active-avoidance learning by modulation of synaptic efficiency in rats.

  14. α1-Adrenoceptors in the hippocampal dentate gyrus involved in learning-dependent long-term potentiation during active-avoidance learning in rats.

    PubMed

    Lv, Jing; Zhan, Su-Yang; Li, Guang-Xie; Wang, Dan; Li, Ying-Shun; Jin, Qing-Hua

    2016-11-01

    The hippocampus is the key structure for learning and memory in mammals and long-term potentiation (LTP) is an important cellular mechanism responsible for learning and memory. The influences of norepinephrine (NE) on the modulation of learning and memory, as well as LTP, through β-adrenoceptors are well documented, whereas the role of α1-adrenoceptors in learning-dependent LTP is not yet clear. In the present study, we measured extracellular concentrations of NE in the hippocampal dentate gyrus (DG) region using an in-vivo brain microdialysis and high-performance liquid chromatography techniques during the acquisition and extinction of active-avoidance behavior in freely moving conscious rats. Next, the effects of prazosin (an antagonist of α1-adrenoceptor) and phenylephrine (an agonist of the α1-adrenoceptor) on amplitudes of field excitatory postsynaptic potential were measured in the DG region during the active-avoidance behavior. Our results showed that the extracellular concentration of NE in the DG was significantly increased during the acquisition of active-avoidance behavior and gradually returned to the baseline level following extinction training. A local microinjection of prazosin into the DG significantly accelerated the acquisition of the active-avoidance behavior, whereas a local microinjection of phenylephrine retarded the acquisition of the active-avoidance behavior. Furthermore, in all groups, the changes in field excitatory postsynaptic potential amplitude were accompanied by corresponding changes in active-avoidance behavior. Our results suggest that NE activation of α1-adrenoceptors in the hippocampal DG inhibits active-avoidance learning by modulation of synaptic efficiency in rats. PMID:27603730

  15. Vulnerability factors in anxiety: Strain and sex differences in the use of signals associated with non-threat during the acquisition and extinction of active-avoidance behavior.

    PubMed

    Beck, Kevin D; Jiao, Xilu; Ricart, Thomas M; Myers, Catherine E; Minor, Thomas R; Pang, Kevin C H; Servatius, Richard J

    2011-08-15

    Rats that exhibit a behaviorally inhibited temperament acquire active-avoidance behaviors quicker, and extinguish them slower, than normal outbred rats. Here we explored the contribution of stimuli that signal periods of non-threat (i.e. safety signals) in the process of acquiring active-avoidance behavior. Utilizing a discrete lever-press escape-avoidance protocol, outbred Sprague-Dawley (SD) rats and inbred, behaviorally inhibited, Wistar-Kyoto (WKY) rats were tested under conditions where a flashing light was either presented or not during periods of non-threat (the inter-trial interval, ITI). For males, we found the absence of the ITI-signal slowed the acquisition of avoidance behavior selectively in WKY rats. However, extinction of the avoidance behavior was not influenced by training with or without the ITI-signal; WKY males extinguished slower than SD males. For females, the presence of the ITI-signal did not affect acquisition in either strain. However, after training with the ITI-signal, females of both strains extinguished quicker in its absence than in its presence. In order to determine if facilitated acquisition of avoidance learning in male WKY rats was due to a paradigm-independent influence of the visual stimulus used as ITI-signal upon associative learning, we conducted eyeblink conditioning in the presence or absence of a similar visual stimulus. No differences in acquisition, as a function of this visual stimulus, were observed within the male WKY rats, but, as was observed in avoidance learning, male WKY rats extinguished slower than male SD rats. Thus, avoidance susceptibility for male WKY rats may be tied both to the presence of non-threat signals as well as a resistance to extinguish Pavlovian-conditioned associations. Female susceptibility to resist extinguishing avoidant behavior is discussed with respect to the possible role of stimuli serving as occasion setters for threat contexts.

  16. Electrical Stimulation of Lateral Habenula during Learning: Frequency-Dependent Effects on Acquisition but Not Retrieval of a Two-Way Active Avoidance Response

    PubMed Central

    Wetzel, Wolfram; Scheich, Henning; Ohl, Frank W.

    2013-01-01

    The lateral habenula (LHb) is an epithalamic structure involved in signaling reward omission and aversive stimuli, and it inhibits dopaminergic neurons during motivated behavior. Less is known about LHb involvement in the acquisition and retrieval of avoidance learning. Our previous studies indicated that brief electrical stimulation of the LHb, time-locked to the avoidance of aversive footshock (presumably during the positive affective “relief” state that occurs when an aversive outcome is averted), inhibited the acquisition of avoidance learning. In the present study, we used the same paradigm to investigate different frequencies of LHb stimulation. The effect of 20 Hz vs. 50 Hz vs. 100 Hz stimulation was investigated during two phases, either during acquisition or retrieval in Mongolian gerbils. The results indicated that 50 Hz, but not 20 Hz, was sufficient to produce a long-term impairment in avoidance learning, and was somewhat more effective than 100 Hz in this regard. None of the stimulation parameters led to any effects on retrieval of avoidance learning, nor did they affect general motor activity. This suggests that, at frequencies in excess of the observed tonic firing rates of LHb neurons (>1–20 Hz), LHb stimulation may serve to interrupt the consolidation of new avoidance memories. However, these stimulation parameters are not capable of modifying avoidance memories that have already undergone extensive consolidation. PMID:23840355

  17. Pre- and postnatally administered ACTH, Organon 2766 and CRF facilitate or inhibit active avoidance task performance in young adult mice.

    PubMed

    Honour, L C; White, M H

    1988-01-01

    This study investigated the effect of learning/memory-related neuropeptides on behavioral task performance in later life. A 1 mg/kg dosage of adrenocorticotropic hormone 4-9, Organon 2766, ACTH/MSH 4-10, ACTH 1-24, CRF, or diluent was subcutaneously injected into either pregnant females or into newborn pups during specific neural developmental windows. Each of the progeny was trained in an active-avoidance task and tested for acquisition on postpartum days 35-37. The mice were then tested for memory task performance and reacquisition on days 42-44 postpartum using the identical experimental paradigm as that used in the training sessions. Prenatal treatment with these memory-related neuropeptides resulted in significant facilitation of learning/memory task performance in male and female mice treated with Organon 2766 (p less than 0.001), and a significant inhibition of learning/memory task performance in males and females treated with ACTH 1-24 (p less than 0.01). Additional sex-specific performance facilitations and inhibitions resulted from the pre- or postnatal administration of the various neuropeptides used in this study. These results suggest that neuropeptides, when available in increased amounts during specific neural developmental windows, can significantly improve or suppress related behavioral performance capability in later life.

  18. Redundancy in the World of MAP Kinases: All for One

    PubMed Central

    Saba-El-Leil, Marc K.; Frémin, Christophe; Meloche, Sylvain

    2016-01-01

    The protein kinases ERK1 and ERK2 are the effector components of the prototypical ERK1/2 mitogen-activated protein (MAP) kinase pathway. This signaling pathway regulates cell proliferation, differentiation and survival, and is essential for embryonic development and cellular homeostasis. ERK1 and ERK2 homologs share similar biochemical properties but whether they exert specific physiological functions or act redundantly has been a matter of controversy. However, recent studies now provide compelling evidence in support of functionally redundant roles of ERK1 and ERK2 in embryonic development and physiology. In this review, we present a critical assessment of the evidence for the functional specificity or redundancy of MAP kinase isoforms. We focus on the ERK1/ERK2 pathway but also discuss the case of JNK and p38 isoforms. PMID:27446918

  19. Facilitation and nonfacilitation of active avoidance behavior of rats with septal lesions in the shuttle box and running wheel.

    PubMed

    Blatt, R C

    1976-07-01

    It was hypothesized that facilitation of avoidance performance of rats with septal lesions occurs only in tasks that punish responses having the same topography as the avoidance response, such as intertrial responses, or tasks that have aversive consequences for making the avoidance response, such as a brightly illuminated safe compartment. Twenty-eight male rats were trained in two shuttle box tasks, and 24 were trained in two running-wheel avoidance tasks under conditions of punishment or nonpunishment of intertrial responses. Rats with septal lesions performed better than control rats in both the shuttle box and the wheel tasks when intertrial responses were punished. When intertrial responding was not punished, experimental and control groups did not differ in avoidance performance. Avoidance performance of punished and unpunished rats with septal lesions did not differ from each other or from unpunished control rats in either wheel or shuttle box tasks. These results were discussed in the context of the species-specific defense reaction (SSDR) avoidance theory of Bolles. It was suggested that septal lesions interfere with the suppression of ineffective SSDRs.

  20. Active and Avoidant Coping and Coping Efficacy as Mediators of the Relation of Maternal Involvement to Depressive Symptoms among Urban Adolescents

    ERIC Educational Resources Information Center

    Mosher, Catherine E.; Prelow, Hazel M.

    2007-01-01

    Our study tested an extension of the social resource model in an urban sample of 129 African American and 114 European American adolescents. Maternal involvement was positively related to the use of active and avoidant coping strategies among youth of both ethnicities. Additionally, use of active coping strategies was related to greater coping…

  1. Ten weeks of physical-cognitive-mindfulness training reduces fear-avoidance beliefs about work-related activity: Randomized controlled trial.

    PubMed

    Jay, Kenneth; Brandt, Mikkel; Jakobsen, Markus Due; Sundstrup, Emil; Berthelsen, Kasper Gymoese; Schraefel, Mc; Sjøgaard, Gisela; Andersen, Lars L

    2016-08-01

    People with chronic musculoskeletal pain often experience pain-related fear of movement and avoidance behavior. The Fear-Avoidance model proposes a possible mechanism at least partly explaining the development and maintenance of chronic pain. People who interpret pain during movement as being potentially harmful to the organism may initiate a vicious behavioral cycle by generating pain-related fear of movement accompanied by avoidance behavior and hyper-vigilance.This study investigates whether an individually adapted multifactorial approach comprised of biopsychosocial elements, with a focus on physical exercise, mindfulness, and education on pain and behavior, can decrease work-related fear-avoidance beliefs.As part of a large scale 10-week worksite randomized controlled intervention trial focusing on company initiatives to combat work-related musculoskeletal pain and stress, we evaluated fear-avoidance behavior in 112 female laboratory technicians with chronic neck, shoulder, upper back, lower back, elbow, and hand/wrist pain using the Fear-Avoidance Beliefs Questionnaire at baseline, before group allocation, and again at the post intervention follow-up 10 weeks later.A significant group by time interaction was observed (P < 0.05) for work-related fear-avoidance beliefs. The between-group difference at follow-up was -2.2 (-4.0 to -0.5), corresponding to a small to medium effect size (Cohen's d = 0.30).Our study shows that work-related, but not leisure time activity-related, fear-avoidance beliefs, as assessed by the Fear-avoidance Beliefs Questionnaire, can be significantly reduced by 10 weeks of physical-cognitive-mindfulness training in female laboratory technicians with chronic pain.

  2. Ten weeks of physical-cognitive-mindfulness training reduces fear-avoidance beliefs about work-related activity: Randomized controlled trial.

    PubMed

    Jay, Kenneth; Brandt, Mikkel; Jakobsen, Markus Due; Sundstrup, Emil; Berthelsen, Kasper Gymoese; Schraefel, Mc; Sjøgaard, Gisela; Andersen, Lars L

    2016-08-01

    People with chronic musculoskeletal pain often experience pain-related fear of movement and avoidance behavior. The Fear-Avoidance model proposes a possible mechanism at least partly explaining the development and maintenance of chronic pain. People who interpret pain during movement as being potentially harmful to the organism may initiate a vicious behavioral cycle by generating pain-related fear of movement accompanied by avoidance behavior and hyper-vigilance.This study investigates whether an individually adapted multifactorial approach comprised of biopsychosocial elements, with a focus on physical exercise, mindfulness, and education on pain and behavior, can decrease work-related fear-avoidance beliefs.As part of a large scale 10-week worksite randomized controlled intervention trial focusing on company initiatives to combat work-related musculoskeletal pain and stress, we evaluated fear-avoidance behavior in 112 female laboratory technicians with chronic neck, shoulder, upper back, lower back, elbow, and hand/wrist pain using the Fear-Avoidance Beliefs Questionnaire at baseline, before group allocation, and again at the post intervention follow-up 10 weeks later.A significant group by time interaction was observed (P < 0.05) for work-related fear-avoidance beliefs. The between-group difference at follow-up was -2.2 (-4.0 to -0.5), corresponding to a small to medium effect size (Cohen's d = 0.30).Our study shows that work-related, but not leisure time activity-related, fear-avoidance beliefs, as assessed by the Fear-avoidance Beliefs Questionnaire, can be significantly reduced by 10 weeks of physical-cognitive-mindfulness training in female laboratory technicians with chronic pain. PMID:27559939

  3. Initiation of phospholipomannan β-1,2 mannosylation involves Bmts with redundant activity, influences its cell wall location and regulates β-glucans homeostasis but is dispensable for Candida albicans systemic infection.

    PubMed

    Courjol, F; Mille, C; Hall, R A; Masset, A; Aijjou, R; Gow, N A R; Poulain, D; Jouault, T; Fradin, C

    2016-01-01

    Pathogenic and non-pathogenic fungi synthesize glycosphingolipids, which have a crucial role in growth and viability. Glycosphingolipids also contribute to fungal-associated pathogenesis. The opportunistic yeast pathogen Candida albicans synthesizes phospholipomannan (PLM), which is a glycosphingolipid of the mannosylinositol phosphorylceramide family. Through its lipid and glycan moieties, PLM contributes to the initial recognition of the yeast, causing immune system disorder and persistent fungal disease through activation of host signaling pathways. The lipid moiety of PLM activates the deregulation signaling pathway involved in yeast phagocytosis whereas its glycan moiety, composed of β-1,2 mannosides (β-Mans), participates to inflammatory processes through a mechanism involving Galectin-3. Biosynthesis of PLM β-Mans involves two β-1,2 mannosyltransferases (Bmts) that initiate (Bmt5) and elongate (Bmt6) the glycan chains. After generation of double bmtsΔ mutants, we show that Bmt5 has redundant activity with Bmt2, which can replace Bmt5 in bmt5Δ mutant. We also report that PLM is located in the inner layer of the yeast cell wall. PLM seems to be not essential for systemic infection of the yeast. However, defect of PLM β-mannosylation increases resistance of C. albicans to inhibitors of β-glucans and chitin synthesis, highlighting a role of PLM in cell wall homeostasis.

  4. Training in the step-down inhibitory avoidance task time-dependently increases cAMP-dependent protein kinase activity in the entorhinal cortex.

    PubMed

    Pereira, P; Ardenghi, P; Mello e Souza, T; Medina, J H; Izquierdo, I

    2001-06-01

    The cAMP/cAMP-dependent protein kinase (PKA) signaling pathway has been implicated in synaptic plasticity changes and memory consolidation. Several cortical structures are involved in the consolidation of memory for inhibitory avoidance. The aim of the present work was to observe the effects of training in the inhibitory avoidance task on the levels of PKA activity in the entorhinal, parietal and posterior cingulate cortex (EC, PARIET and PC), and the medial precentral area (Fr2) of the rat, at different post-training times (0, 1.5, 3 and 6h). PKA activity, assayed using [gamma-32P]ATP and kemptide, a selective substrate, increased in the EC 3 h after training, but no changes were observed in PARIET, PC and Fr2. These results suggest that the late phase of memory consolidation of inhibitory avoidance requires a functional PKA signaling pathway in the EC in a way that a 'peak' of PKA activity is observed.

  5. In-flight performance optimization for rotorcraft with redundant controls

    NASA Astrophysics Data System (ADS)

    Ozdemir, Gurbuz Taha

    establish a schedule. The method has been expanded to search a two-dimensional control space. Simulation results demonstrate the ability to maximize range by optimizing stabilator deflection and an airspeed set point. Another set of results minimize power required in high speed flight by optimizing collective pitch and stabilator deflection. Results show that the control laws effectively hold the flight condition while the FTO method is effective at improving performance. Optimizations show there can be issues when the control laws regulating altitude push the collective control towards it limits. So a modification was made to the control law to regulate airspeed and altitude using propeller pitch and angle of attack while the collective is held fixed or used as an optimization variable. A dynamic trim limit avoidance algorithm is applied to avoid control saturation in other axes during optimization maneuvers. Range and power optimization FTO simulations are compared with comprehensive sweeps of trim solutions and FTO optimization shown to be effective and reliable in reaching an optimal when optimizing up to two redundant controls. Use of redundant controls is shown to be beneficial for improving performance. The search method takes almost 25 minutes of simulated flight for optimization to be complete. The optimization maneuver itself can sometimes drive the power required to high values, so a power limit is imposed to restrict the search to avoid conditions where power is more than5% higher than that of the initial trim state. With this modification, the time the optimization maneuver takes to complete is reduced down to 21 minutes without any significant change in the optimal power value.

  6. Timing control by redundant inhibitory neuronal circuits

    SciTech Connect

    Tristan, I. Rulkov, N. F.; Huerta, R.; Rabinovich, M.

    2014-03-15

    Rhythms and timing control of sequential activity in the brain is fundamental to cognition and behavior. Although experimental and theoretical studies support the understanding that neuronal circuits are intrinsically capable of generating different time intervals, the dynamical origin of the phenomenon of functionally dependent timing control is still unclear. Here, we consider a new mechanism that is related to the multi-neuronal cooperative dynamics in inhibitory brain motifs consisting of a few clusters. It is shown that redundancy and diversity of neurons within each cluster enhances the sensitivity of the timing control with the level of neuronal excitation of the whole network. The generality of the mechanism is shown to work on two different neuronal models: a conductance-based model and a map-based model.

  7. Timing control by redundant inhibitory neuronal circuits

    NASA Astrophysics Data System (ADS)

    Tristan, I.; Rulkov, N. F.; Huerta, R.; Rabinovich, M.

    2014-03-01

    Rhythms and timing control of sequential activity in the brain is fundamental to cognition and behavior. Although experimental and theoretical studies support the understanding that neuronal circuits are intrinsically capable of generating different time intervals, the dynamical origin of the phenomenon of functionally dependent timing control is still unclear. Here, we consider a new mechanism that is related to the multi-neuronal cooperative dynamics in inhibitory brain motifs consisting of a few clusters. It is shown that redundancy and diversity of neurons within each cluster enhances the sensitivity of the timing control with the level of neuronal excitation of the whole network. The generality of the mechanism is shown to work on two different neuronal models: a conductance-based model and a map-based model.

  8. Reduced Redundancy as a Language Testing Tool.

    ERIC Educational Resources Information Center

    Spolsky, Bernard

    Redundancy in language reduces the possiblity of error and permits communication where there is interference in the communicating channel. The relationship between creativity (the basic distinction between language-like behavior and knowing a language) and redundancy has been clearly established. Knowledge of rules is the key factor in creativity…

  9. Synchronous transfer circuits for redundant systems

    NASA Technical Reports Server (NTRS)

    Nagano, S.

    1978-01-01

    Circuit arrangements for flip-flops, counters, and clock drivers in redundant systems ensure that control is synchronously transferred to surviving components when failure occurs. In addition to original application to spacecraft systems, redundant circuits have terrestrial uses in power generators, solar-energy converters, computers, vehicle controllers, and other systems demanding high reliability.

  10. RGS Redundancy and Implications in GPCR-GIRK Signaling.

    PubMed

    Doupnik, Craig A

    2015-01-01

    Regulators of G protein signaling (RGS proteins) are key components of GPCR complexes, interacting directly with G protein α-subunits to enhance their intrinsic GTPase activity. The functional consequence is an accelerated termination of G protein effectors including certain ion channels. RGS proteins have a profound impact on the membrane-delimited gating behavior of G-protein-activated inwardly rectifying K(+) (GIRK) channels as demonstrated in reconstitution assays and recent RGS knockout mice studies. Akin to GPCRs and G protein αβγ subunits, multiple RGS isoforms are expressed within single GIRK-expressing neurons, suggesting functional redundancy and/or specificity in GPCR-GIRK channel signaling. The extent and impact of RGS redundancy in neuronal GPCR-GIRK channel signaling is currently not fully appreciated; however, recent studies from RGS knockout mice are providing important new clues on the impact of individual endogenous RGS proteins and the extent of RGS functional redundancy. Incorporating "tools" such as engineered RGS-resistant Gαi/o subunits provide an important assessment method for determining the impact of all endogenous RGS proteins on a given GPCR response and an accounting benchmark to assess the impact of individual RGS knockouts on overall RGS redundancy within a given neuron. Elucidating the degree of regulation attributable to specific RGS proteins in GIRK channel function will aid in the assessment of individual RGS proteins as viable therapeutic targets in epilepsy, ataxia's, memory disorders, and a growing list of neurological disorders.

  11. Absence of "Warm-Up" during Active Avoidance Learning in a Rat Model of Anxiety Vulnerability: Insights from Computational Modeling.

    PubMed

    Myers, Catherine E; Smith, Ian M; Servatius, Richard J; Beck, Kevin D

    2014-01-01

    Avoidance behaviors, in which a learned response causes omission of an upcoming punisher, are a core feature of many psychiatric disorders. While reinforcement learning (RL) models have been widely used to study the development of appetitive behaviors, less attention has been paid to avoidance. Here, we present a RL model of lever-press avoidance learning in Sprague-Dawley (SD) rats and in the inbred Wistar Kyoto (WKY) rat, which has been proposed as a model of anxiety vulnerability. We focus on "warm-up," transiently decreased avoidance responding at the start of a testing session, which is shown by SD but not WKY rats. We first show that a RL model can correctly simulate key aspects of acquisition, extinction, and warm-up in SD rats; we then show that WKY behavior can be simulated by altering three model parameters, which respectively govern the tendency to explore new behaviors vs. exploit previously reinforced ones, the tendency to repeat previous behaviors regardless of reinforcement, and the learning rate for predicting future outcomes. This suggests that several, dissociable mechanisms may contribute independently to strain differences in behavior. The model predicts that, if the "standard" inter-session interval is shortened from 48 to 24 h, SD rats (but not WKY) will continue to show warm-up; we confirm this prediction in an empirical study with SD and WKY rats. The model further predicts that SD rats will continue to show warm-up with inter-session intervals as short as a few minutes, while WKY rats will not show warm-up, even with inter-session intervals as long as a month. Together, the modeling and empirical data indicate that strain differences in warm-up are qualitative rather than just the result of differential sensitivity to task variables. Understanding the mechanisms that govern expression of warm-up behavior in avoidance may lead to better understanding of pathological avoidance, and potential pathways to modify these processes. PMID:25183956

  12. Intra-Amygdala ZIP Injections Impair the Memory of Learned Active Avoidance Responses and Attenuate Conditioned Taste-Aversion Acquisition in Rats

    ERIC Educational Resources Information Center

    Gamiz, Fernando; Gallo, Milagros

    2011-01-01

    We have investigated the effect of protein kinase Mzeta (PKM[zeta]) inhibition in the basolateral amygdala (BLA) upon the retention of a nonspatial learned active avoidance response and conditioned taste-aversion (CTA) acquisition in rats. ZIP (10 nmol/[mu]L) injected into the BLA 24 h after training impaired retention of a learned…

  13. Fully redundant mechanical release actuator

    NASA Technical Reports Server (NTRS)

    Lucy, Melvin H. (Inventor)

    1987-01-01

    A system is described for performing a mechanical release function exhibiting low shock. This system includes two pyrotechnic detents fixed mounted in opposing axial alignment within a cylindrical housing having two mechanical bellows. Two mechanical bellow assemblies, each having one end hermetically bonded to the housing and the other to the respective actuator pin extending from either end of the housing, ensure that all outgassing and contamination from the operation of the pyrotechnic devices will be contained within the housing and bellows. The pin on one end of the assembly is fixed mounted and supported, via a bolt or ball-and-socket joint so that when the charge corresponding to that pin ignites, the entire assembly will exhibit rectilinear movement, including the opposing pin providing the unlatching motion. The release detent pin is supported by a linear bearing and when its corresponding pyrotechnic charge ignites the pin is retracted within the housing producing the same unlatching motion without movement of the entire assembly, thus providing complete mechanical, electrical and pyrotechnic redundancy for the unlatching pin.

  14. Redundant arrays of IDE drives

    SciTech Connect

    D.A. Sanders et al.

    2002-01-02

    The authors report tests of redundant arrays of IDE disk drives for use in offline high energy physics data analysis. Parts costs of total systems using commodity EIDE disks are now at the $4000 per Terabyte level. Disk storage prices have now decreased to the point where they equal the cost per Terabyte of Storage Technology tape silos. The disks, however, offer far better granularity; even small institutions can afford to deploy systems. The tests include reports on software RAID-5 systems running under Linux 2.4 using Promise Ultra 100{trademark} disk controllers. RAID-5 protects data in case of a single disk failure by providing parity bits. Tape backup is not required. Journaling file systems are used to allow rapid recovery from crashes. The data analysis strategy is to encapsulate data and CPU processing power. Analysis for a particular part of a data set takes place on the PC where the data resides. The network is only used to put results together. They explore three methods of moving data between sites; internet transfers, not pluggable IDE disks in FireWire cases, and DVD-R disks.

  15. Two Redundant Receptor-Like Cytoplasmic Kinases Function Downstream of Pattern Recognition Receptors to Regulate Activation of SA Biosynthesis1[OPEN

    PubMed Central

    Kong, Qing; Qu, Na; Ma, Junling; Li, Meng; Cheng, Yu-ti; Zhang, Qian; Wu, Di; Zhang, Zhibin; Zhang, Yuelin

    2016-01-01

    Salicylic acid (SA) serves as a critical signaling molecule in plant defense. Two transcription factors, SARD1 and CBP60g, control SA biosynthesis through regulating pathogen-induced expression of Isochorismate Synthase1, which encodes a key enzyme for SA biosynthesis. Here, we report that Pattern-Triggered Immunity Compromised Receptor-like Cytoplasmic Kinase1 (PCRK1) and PCRK2 function as key regulators of SA biosynthesis. In the pcrk1 pcrk2 double mutant, pathogen-induced expression of SARD1, CBP60g, and ICS1 is greatly reduced. The pcrk1 pcrk2 double mutant, but neither of the single mutants, exhibits reduced accumulation of SA and enhanced disease susceptibility to bacterial pathogens. Both PCRK1 and PCRK2 interact with the pattern recognition receptor FLS2, and treatment with pathogen-associated molecular patterns leads to rapid phosphorylation of PCRK2. Our data suggest that PCRK1 and PCRK2 function downstream of pattern recognition receptor in a signal relay leading to the activation of SA biosynthesis. PMID:27208222

  16. Redundant information encoding in primary motor cortex during natural and prosthetic motor control.

    PubMed

    So, Kelvin; Ganguly, Karunesh; Jimenez, Jessica; Gastpar, Michael C; Carmena, Jose M

    2012-06-01

    Redundant encoding of information facilitates reliable distributed information processing. To explore this hypothesis in the motor system, we applied concepts from information theory to quantify the redundancy of movement-related information encoded in the macaque primary motor cortex (M1) during natural and neuroprosthetic control. Two macaque monkeys were trained to perform a delay center-out reaching task controlling a computer cursor under natural arm movement (manual control, 'MC'), and using a brain-machine interface (BMI) via volitional control of neural ensemble activity (brain control, 'BC'). During MC, we found neurons in contralateral M1 to contain higher and more redundant information about target direction than ipsilateral M1 neurons, consistent with the laterality of movement control. During BC, we found that the M1 neurons directly incorporated into the BMI ('direct' neurons) contained the highest and most redundant target information compared to neurons that were not incorporated into the BMI ('indirect' neurons). This effect was even more significant when comparing to M1 neurons of the opposite hemisphere. Interestingly, when we retrained the BMI to use ipsilateral M1 activity, we found that these neurons were more redundant and contained higher information than contralateral M1 neurons, even though ensembles from this hemisphere were previously less redundant during natural arm movement. These results indicate that ensembles most associated to movement contain highest redundancy and information encoding, which suggests a role for redundancy in proficient natural and prosthetic motor control.

  17. File I/O for MPI Applications in Redundant Execution Scenarios

    SciTech Connect

    Boehm, Swen; Engelmann, Christian

    2012-01-01

    As multi-petascale and exa-scale high-performance computing (HPC) systems inevitably have to deal with a number of resilience challenges, such as a significant growth in component count and smaller circuit sizes with lower circuit voltages, redundancy may offer an acceptable level of resilience that traditional fault tolerance techniques, such as checkpoint/restart, do not. Although redundancy in HPC is quite controversial due to the associated cost for redundant components, the constantly increasing number of cores-per-processor is tilting this cost calculation toward a system design where computation, such as for redundancy, is much cheaper and communication, needed for checkpoint/restart, is much more expensive. Recent research and development activities in redundancy for Message Passing Interface (MPI) applications focused on availability/reliability models and replication algorithms. This paper takes a first step toward solving an open research problem associated with running a parallel application redundantly, which is file I/O under redundancy. The approach intercepts file I/O calls made by a redundant application to employ coordination protocols that execute file I/O operations in a redundancy-oblivious fashion when accessing a node-local file system, or in a redundancy-aware fashion when accessing a shared networked file system. A proof-of concept prototype is presented and a number of coordination protocols are described and evaluated. The results show the performance impact for redundantly accessing a shared networked file system, but also demonstrate the capability to regain performance by utilizing MPI communication between replicas and parallel file I/O.

  18. Effects of ionizing radiation and restraint stress on activity, avoidance conditioning, and stomach ulcers in albino rats. Final report October 1980-December 1981

    SciTech Connect

    Lanum, J.; Blick, D.W.; Campbell, M.E.; Wheeler, T.G.; Koger, S.A.

    1984-03-01

    In an experiment with albino rats, we have tried to model a nuclear attack scenario in which military personnel receiving 600 to 800 rads of ionizing radiation would be making a counterattack under the stress of an emergency situation. We used a dose of radiation that, though higher than the human exposure field, was estimated to be its physiological equivalent. Restraining the rat in an immobile position, a technique previously shown to have stressing qualities for rats, was chosen as an analogy to the stress of being in a war emergency. Activity and conditioned avoidance acquisition were chosen as test responses. Performance in the activity maze was affected only to a minor degree and in the direction of considering irradiation as activating. However, all irradiated groups showed retarded conditioned avoidance acquisition, which can be interpreted as decreased adaptability to a stressful situation. Further, our results support the expectation of performance decrements in the military scenario that could not be predicted by considering ionizing radiation in isolation. On the avoidance task, male rats in the combination stress-irradiation condition showed more failures to respond and longer response latencies than any other group. Female rats, on the other hand, showed shorter escape/avoidance latencies in the combined stress-irradiation condition than in the irradiation condition alone. This sex difference may be useful as a clue for investigating mechanisms of radiation resistance and interactions between stressors.

  19. Pathway knockout and redundancy in metabolic networks.

    PubMed

    Min, Yong; Jin, Xiaogang; Chen, Ming; Pan, Zhengzheng; Ge, Ying; Chang, Jie

    2011-02-01

    The robustness and stability of complex cellular networks is often attributed to the redundancy of components, including genes, enzymes and pathways. Estimation of redundancy is still an open question in systems biology. Current theoretical tools to measure redundancy have various strengths and shortcomings in providing a comprehensive description of metabolic networks. Specially, there is a lack of effective measures to cover different perturbation situations. Here we present a pathway knockout algorithm to improve quantitative measure of redundancy in metabolic networks grounded on the elementary flux mode (EFM) analysis. The proposed redundancy measure is based on the average ratio of remaining EFMs after knockout of one EFM in the unperturbed state. We demonstrated with four example systems that our algorithm overcomes limits of previous measures, and provides additional information about redundancy in the situation of targeted attacks. Additionally, we compare existing enzyme knockout and our pathway knockout algorithm by the mean-field analysis, which provides mathematical expression for the average ratio of remaining EFMs after both types of knockout. Our results prove that multiple-enzymes knockout does not always yield more information than single-enzyme knockout for evaluating redundancy. Indeed, pathway knockout considers additional effects of structural asymmetry. In the metabolic networks of amino acid anabolism in Escherichia coli and human hepatocytes, and the central metabolism in human erythrocytes, we validate our mean-field solutions and prove the capacity of pathway knockout algorithm. Moreover, in the E. coli model the two sub-networks synthesizing amino acids that are essential and those that are non-essential for humans are studied separately. In contrast to previous studies, we find that redundancy of two sub-networks is similar with each other, and even sub-networks synthesizing essential amino acids can be more redundant.

  20. Bacterial Functional Redundancy along a Soil Reclamation Gradient

    PubMed Central

    Yin, Bei; Crowley, David; Sparovek, Gerd; De Melo, Wanderley Jose; Borneman, James

    2000-01-01

    A strategy to measure bacterial functional redundancy was developed and tested with soils collected along a soil reclamation gradient by determining the richness and diversity of bacterial groups capable of in situ growth on selected carbon substrates. Soil cores were collected from four sites along a transect from the Jamari tin mine site in the Jamari National Forest, Rondonia, RO, Brazil: denuded mine spoil, soil from below the canopy of invading pioneer trees, revegetated soil under new growth on the forest edge, and the forest floor of an adjacent preserved forest. Bacterial population responses were analyzed by amending these soil samples with individual carbon substrates in the presence of bromodeoxyuridine (BrdU). BrdU-labeled DNA was then subjected to a 16S-23S rRNA intergenic analysis to depict the actively growing bacteria from each site. The number and diversity of bacterial groups responding to four carbon substrates (l-serine, l-threonine, sodium citrate, and α-lactose hydrate) increased along the reclamation-vegetation gradient such that the preserved forest soil samples contained the highest functional redundancy for each substrate. These data suggest that bacterial functional redundancy increases in relation to the regrowth of plant communities and may therefore represent an important aspect of the restoration of soil biological functionality to reclaimed mine spoils. They also suggest that bacterial functional redundancy may be a useful indicator of soil quality and ecosystem functioning. PMID:11010883

  1. Spectral Redundancy in Tissue Characterization

    NASA Astrophysics Data System (ADS)

    Varghese, Tomy

    1995-01-01

    Ultrasonic backscattered signals from material comprised of quasi-periodic scatterers exhibit redundancy over both its phase and magnitude spectra. This dissertation addresses the problem of estimating the mean scatterer spacing and scatterer density from the backscattered ultrasound signal using spectral redundancy characterized by the spectral autocorrelation (SAC) function. The SAC function exploits characteristic differences between the phase spectrum of the resolvable quasi-periodic (regular) scatterers and the unresolvable uniformly distributed (diffuse) scatterers to improve estimator performance over other estimators that operate directly on the magnitude spectrum. Analytical, simulation, and experimental results (liver and breast tissue) indicate the potential of utilizing phase information using the SAC function. A closed form analytical expression for the SAC function is derived for gamma distributed scatterer spacings. The theoretical expression for the SAC function demonstrate the increased regular-to-diffuse scatterer signal ratio in the off-diagonal components of the SAC function, since the diffuse component contributes only to the diagonal components (power spectrum). The A-scan is modelled as a cyclostationary signal whose statistical parameters vary in time with single or multiple periodicities. A-scan models consist of a collection of regular scatterers with gamma distributed spacings embedded in diffuse scatterers with uniform distributed spacings. The model accounts for attenuation by convolving the frequency dependent backscatter coefficients of the scatterer centers with a time-varying system response. Simulation results show that SAC-based estimates converge more reliably over smaller amounts of data than previously used cepstrum-based estimates. A major reason for the performance advantage is the use of phase information by the SAC function, while the cepstnun uses a phaseless power spectral density, that is directly affected by the system

  2. Redundant publications in the orthopedic literature.

    PubMed

    Eck, Jason C; Nachtigall, Dean; Hodges, Scott D; Humphreys, S Craig

    2007-01-01

    Rates of redundant publications in the general surgery literature are approximately 14%. This article identifies the rate of redundant publications in the orthopedic literature. All original articles published during the year 2000 in The Journal of Bone and Joint Surgery (American Volume), Journal of Orthopaedic Trauma, Journal of Spinal Disorders, and Spine were searched using PubMed. Redundancy rate was 4 (3.15%) of 127 for The Journal of Bone and Joint Surgery (American volume), zero (0%) of 70 for Journal of Orthopaedic Trauma, 2 (2.90%) of 69 for Journal of Spinal Disorders, and 11 (3.12%) of 353 for Spine.

  3. Redundant correlation effect on personalized recommendation

    NASA Astrophysics Data System (ADS)

    Qiu, Tian; Han, Teng-Yue; Zhong, Li-Xin; Zhang, Zi-Ke; Chen, Guang

    2014-02-01

    The high-order redundant correlation effect is investigated for a hybrid algorithm of heat conduction and mass diffusion (HHM), through both heat conduction biased (HCB) and mass diffusion biased (MDB) correlation redundancy elimination processes. The HCB and MDB algorithms do not introduce any additional tunable parameters, but keep the simple character of the original HHM. Based on two empirical datasets, the Netflix and MovieLens, the HCB and MDB are found to show better recommendation accuracy for both the overall objects and the cold objects than the HHM algorithm. Our work suggests that properly eliminating the high-order redundant correlations can provide a simple and effective approach to accurate recommendation.

  4. Localized injections of various compounds effecting neurotransmitter activity in the mammillary complex enhance (T-maze) avoidance retention.

    PubMed

    Flood, J F; Scherrer, J F; Morley, J E

    1995-03-14

    The mammillary complex is implicated in the amnesic syndrome associated clinically with Korsakoff's syndrome, Alzheimer's disease and experimentally with lesions in animals. There is however no direct evidence that the mammillary bodies are involved in long term memory processing. Mice were partially trained on a footshock avoidance task. Immediately after training drugs were injected into the mammillary complex. Retention was tested 1 week later by continuing training until each mouse made five avoidance responses in six trials. The results indicated that muscarine, nicotine, dopamine, glutamine and adrenoceptor agonists as well as GABA and 5-HT receptor antagonists and neuropeptide Y improved retention test performance relative to the control. Injection of the same drugs 1 mm above the injection site for the mammillary complex failed to significantly improve retention test performance. It is concluded that the mammillary complex, with its important connections to other areas of the limbic system, is involved in memory processing events that occur shortly after training.

  5. [Effect of serotonin on the activity of the neurons involved in the realization of the avoidance reflex of the snail].

    PubMed

    Chistiakova, M V; Balaban, P M

    1988-01-01

    Bath application of 10(-5) mol/l of serotonin (5-HT) elicited a 50% increase of summary EPSPs recorded in command neurones for avoidance behaviour. No significant changes of rest potential and input resistance were seen in these cells. 5-HT evoked an increase of spontaneous level of firing in motoneurones involved in the same reflex, as well as an increase in the number of spikes which paralleled increase of EPSPs to the same stimulus in command neurones. In sensory cells, presynaptic to the command neurones, application of 5-HT evoked a significant increase of excitability and of input resistance. Monosynaptic EPSPs recorded in the command neurones showed a 40% increase after serotonin application. It is concluded that the major locus of plastic changes evoked by 5-HT application in the neuronal chain underlying avoidance reflex is the synaptic contact between sensory and command neurones.

  6. The Effects of Race Conditions When Implementing Single-Source Redundant Clock Trees in Triple Modular Redundant Synchronous Architectures

    NASA Technical Reports Server (NTRS)

    Berg, Melanie D.; Kim, Hak S.; Phan, Anthony M.; Seidleck, Christina M.; Label, Kenneth A.; Pellish, Jonathan A.; Campola, Michael J.

    2016-01-01

    We present the challenges that arise when using redundant clock domains due to their time-skew. Radiation data show that a singular clock domain provides an improved triple modular redundant (TMR) scheme over redundant clocks.

  7. Extensibility in local sensor based planning for hyper-redundant manipulators (robot snakes)

    NASA Technical Reports Server (NTRS)

    Choset, Howie; Burdick, Joel

    1994-01-01

    Partial Shape Modification (PSM) is a local sensor feedback method used for hyper-redundant robot manipulators, in which the redundancy is very large or infinite such as that of a robot snake. This aspect of redundancy enables local obstacle avoidance and end-effector placement in real time. Due to the large number of joints or actuators in a hyper-redundant manipulator, small displacement errors of such easily accumulate to large errors in the position of the tip relative to the base. The accuracy could be improved by a local sensor based planning method in which sensors are distributed along the length of the hyper-redundant robot. This paper extends the local sensor based planning strategy beyond the limitations of the fixed length of such a manipulator when its joint limits are met. This is achieved with an algorithm where the length of the deforming part of the robot is variable. Thus , the robot's local avoidance of obstacles is improved through the enhancement of its extensibility.

  8. Evolutionary preservation of redundant duplicated genes.

    PubMed

    Krakauer, D C; Nowak, M A

    1999-10-01

    Gene duplication events produce both perfect and imperfect copies of genes. Perfect copies are said to be functionally redundant when knockout of one gene produces no 'scoreable', phenotypic effects. Preserving identical, duplicate copies of genes is problematic as all copies are prone to accumulate neutral mutations as pseudogenes, or more rarely, evolve into new genes with novel functions. We summarise theoretical treatments for the invasion and subsequent evolutionary modification of functionally redundant genes. We then consider the preservation of functionally identical copies of a gene over evolutionary time. We present several models for conserving redundancy: asymmetric mutation, asymmetric efficacy, pleiotropy, developmental buffering, allelic competition and regulatory asymmetries. In all cases, some form of symmetry breaking is required to maintain functional redundancy indefinitely.

  9. Teachers Avoiding Learners' Avoidance: Is It Possible?

    ERIC Educational Resources Information Center

    Tadayyon, Maedeh; Zarrinabadi, Nourollah; Ketabi, Saeed

    2016-01-01

    Dealing with learners who prefer to take the back seat and avoid classroom participation can be every teacher's nightmare. This lack of participation may cause teacher frustration, and possibly the only way to reduce this lack of participation is to access the concept of avoidance strategy. Avoidance strategy is the abandonment of a classroom task…

  10. Avoidable waste management costs

    SciTech Connect

    Hsu, K.; Burns, M.; Priebe, S.; Robinson, P.

    1995-01-01

    This report describes the activity based costing method used to acquire variable (volume dependent or avoidable) waste management cost data for routine operations at Department of Energy (DOE) facilities. Waste volumes from environmental restoration, facility stabilization activities, and legacy waste were specifically excluded from this effort. A core team consisting of Idaho National Engineering Laboratory, Los Alamos National Laboratory, Rocky Flats Environmental Technology Site, and Oak Ridge Reservation developed and piloted the methodology, which can be used to determine avoidable waste management costs. The method developed to gather information was based on activity based costing, which is a common industrial engineering technique. Sites submitted separate flow diagrams that showed the progression of work from activity to activity for each waste type or treatability group. Each activity on a flow diagram was described in a narrative, which detailed the scope of the activity. Labor and material costs based on a unit quantity of waste being processed were then summed to generate a total cost for that flow diagram. Cross-complex values were calculated by determining a weighted average for each waste type or treatability group based on the volume generated. This study will provide DOE and contractors with a better understanding of waste management processes and their associated costs. Other potential benefits include providing cost data for sites to perform consistent cost/benefit analysis of waste minimization and pollution prevention (WMIN/PP) options identified during pollution prevention opportunity assessments and providing a means for prioritizing and allocating limited resources for WMIN/PP.

  11. Dizocilpine (MK-801) impairs learning in the active place avoidance task but has no effect on the performance during task/context alternation.

    PubMed

    Vojtechova, Iveta; Petrasek, Tomas; Hatalova, Hana; Pistikova, Adela; Vales, Karel; Stuchlik, Ales

    2016-05-15

    The prevention of engram interference, pattern separation, flexibility, cognitive coordination and spatial navigation are usually studied separately at the behavioral level. Impairment in executive functions is often observed in patients suffering from schizophrenia. We have designed a protocol for assessing these functions all together as behavioral separation. This protocol is based on alternated or sequential training in two tasks testing different hippocampal functions (the Morris water maze and active place avoidance), and alternated or sequential training in two similar environments of the active place avoidance task. In Experiment 1, we tested, in adult rats, whether the performance in two different spatial tasks was affected by their order in sequential learning, or by their day-to-day alternation. In Experiment 2, rats learned to solve the active place avoidance task in two environments either alternately or sequentially. We found that rats are able to acquire both tasks and to discriminate both similar contexts without obvious problems regardless of the order or the alternation. We used two groups of rats, controls and a rat model of psychosis induced by a subchronic intraperitoneal application of 0.08mg/kg of dizocilpine (MK-801), a non-competitive antagonist of NMDA receptors. Dizocilpine had no selective effect on parallel/sequential learning of tasks/contexts. However, it caused hyperlocomotion and a significant deficit in learning in the active place avoidance task regardless of the task alternation. Cognitive coordination tested by this task is probably more sensitive to dizocilpine than spatial orientation because no hyperactivity or learning impairment was observed in the Morris water maze.

  12. Past and present biophysical redundancy of countries as a buffer to changes in food supply

    NASA Astrophysics Data System (ADS)

    Fader, Marianela; Rulli, Maria Cristina; Carr, Joel; Dell'Angelo, Jampel; D'Odorico, Paolo; Gephart, Jessica A.; Kummu, Matti; Magliocca, Nicholas; Porkka, Miina; Prell, Christina; Puma, Michael J.; Ratajczak, Zak; Seekell, David A.; Suweis, Samir; Tavoni, Alessandro

    2016-05-01

    Spatially diverse trends in population growth, climate change, industrialization, urbanization and economic development are expected to change future food supply and demand. These changes may affect the suitability of land for food production, implying elevated risks especially for resource-constrained, food-importing countries. We present the evolution of biophysical redundancy for agricultural production at country level, from 1992 to 2012. Biophysical redundancy, defined as unused biotic and abiotic environmental resources, is represented by the potential food production of ‘spare land’, available water resources (i.e., not already used for human activities), as well as production increases through yield gap closure on cultivated areas and potential agricultural areas. In 2012, the biophysical redundancy of 75 (48) countries, mainly in North Africa, Western Europe, the Middle East and Asia, was insufficient to produce the caloric nutritional needs for at least 50% (25%) of their population during a year. Biophysical redundancy has decreased in the last two decades in 102 out of 155 countries, 11 of these went from high to limited redundancy, and nine of these from limited to very low redundancy. Although the variability of the drivers of change across different countries is high, improvements in yield and population growth have a clear impact on the decreases of redundancy towards the very low redundancy category. We took a more detailed look at countries classified as ‘Low Income Economies (LIEs)’ since they are particularly vulnerable to domestic or external food supply changes, due to their limited capacity to offset for food supply decreases with higher purchasing power on the international market. Currently, nine LIEs have limited or very low biophysical redundancy. Many of these showed a decrease in redundancy over the last two decades, which is not always linked with improvements in per capita food availability.

  13. Past and Present Biophysical Redundancy of Countries as a Buffer to Changes in Food Supply

    NASA Technical Reports Server (NTRS)

    Fader, Marianela; Rulli, Maria Cristina; Carr, Joel; Dell' Angelo, Jampel; D' Odorico, Paolo; Gephart, Jessica A.; Kummu, Matti; Magliocca, Nicholas; Porkka, Miina; Prell, Christina; Puma, Michael J.

    2016-01-01

    Spatially diverse trends in population growth, climate change, industrialization, urbanization and economic development are expected to change future food supply and demand. These changes may affect the suitability of land for food production, implying elevated risks especially for resource constrained, food-importing countries. We present the evolution of biophysical redundancy for agricultural production at country level, from 1992 to 2012. Biophysical redundancy, defined as unused biotic and abiotic environmental resources, is represented by the potential food production of 'spare land', available water resources (i.e., not already used for human activities), as well as production increases through yield gap closure on cultivated areas and potential agricultural areas. In 2012, the biophysical redundancy of 75 (48) countries, mainly in North Africa, Western Europe, the Middle East and Asia, was insufficient to produce the caloric nutritional needs for at least 50% (25%) of their population during a year. Biophysical redundancy has decreased in the last two decades in 102 out of 155 countries, 11 of these went from high to limited redundancy, and nine of these from limited to very low redundancy. Although the variability of the drivers of change across different countries is high, improvements in yield and population growth have a clear impact on the decreases of redundancy towards the very low redundancy category. We took a more detailed look at countries classified as 'Low Income Economies (LIEs)' since they are particularly vulnerable to domestic or external food supply changes, due to their limited capacity to offset for food supply decreases with higher purchasing power on the international market. Currently, nine LIEs have limited or very low biophysical redundancy. Many of these showed a decrease in redundancy over the last two decades, which is not always linked with improvements in per capita food availability.

  14. Redundancy among manganese peroxidases in Pleurotus ostreatus.

    PubMed

    Salame, Tomer M; Knop, Doriv; Levinson, Dana; Yarden, Oded; Hadar, Yitzhak

    2013-04-01

    Manganese peroxidases (MnPs) are key players in the ligninolytic system of white rot fungi. In Pleurotus ostreatus (the oyster mushroom) these enzymes are encoded by a gene family comprising nine members, mnp1 to -9 (mnp genes). Mn(2+) amendment to P. ostreatus cultures results in enhanced degradation of recalcitrant compounds (such as the azo dye orange II) and lignin. In Mn(2+)-amended glucose-peptone medium, mnp3, mnp4, and mnp9 were the most highly expressed mnp genes. After 7 days of incubation, the time point at which the greatest capacity for orange II decolorization was observed, mnp3 expression and the presence of MnP3 in the extracellular culture fluids were predominant. To determine the significance of MnP3 for ligninolytic functionality in Mn(2+)-sufficient cultures, mnp3 was inactivated via the Δku80 strain-based P. ostreatus gene-targeting system. In Mn(2+)-sufficient medium, inactivation of mnp3 did not significantly affect expression of nontargeted MnPs or their genes, nor did it considerably diminish the fungal Mn(2+)-mediated orange II decolorization capacity, despite the significant reduction in total MnP activity. Similarly, inactivation of either mnp4 or mnp9 did not affect orange II decolorization ability. These results indicate functional redundancy within the P. ostreatus MnP gene family, enabling compensation upon deficiency of one of its members. PMID:23377936

  15. “Groundwater hydrology” is redundant

    NASA Astrophysics Data System (ADS)

    While in the Netherlands a few months ago, I mentioned “groundwater hydrology” to a very well-educated, very literary, and non-hydrologic old friend. She shuddered and told me in no uncertain words that this was a horrible term, completely redundant like a round circle, or as the linguists call it, a pleonasm. This is, of course, because hydrology already means water science (from the Greek words udor, or hydor for water, and logos for science), so that groundwater hydrology really stands for groundwater water science, and surface water hydrology for surface water science.These are pleonasms of the first kind and insults to any language purist, which all of us should strive to be! So I propose that henceforth groundwater hydrology be called subterranean hydrology. Other possibilities would be subsurface hydrology, but this sounds too shallow, or underground hydrology, which, however, could give the impression of some clandestine activity. Besides, subterranean hydrology would be in keeping with the words for groundwater in Latin-based languages (eau souterrain in French, acqua sotierranea in Italian, and aguas subterraneas in Spanish). Also, subterranean hydrology includes the vadose zone, which, of course, groundwater hydrology as such does not. Surface water hydrology would simply be called surface hydrology, and anything above that atmospheric hydrology.

  16. Testing conditions in shock-based contextual fear conditioning influence both the behavioral responses and the activation of circuits potentially involved in contextual avoidance.

    PubMed

    Viellard, Juliette; Baldo, Marcus Vinicius C; Canteras, Newton Sabino

    2016-12-15

    Previous studies from our group have shown that risk assessment behaviors are the primary contextual fear responses to predatory and social threats, whereas freezing is the main contextual fear response to physically harmful events. To test contextual fear responses to a predator or aggressive conspecific threat, we developed a model that involves placing the animal in an apparatus where it can avoid the threat-associated environment. Conversely, in studies that use shock-based fear conditioning, the animals are usually confined inside the conditioning chamber during the contextual fear test. In the present study, we tested shock-based contextual fear responses using two different behavioral testing conditions: confining the animal in the conditioning chamber or placing the animal in an apparatus with free access to the conditioning compartment. Our results showed that during the contextual fear test, the animals confined to the shock chamber exhibited significantly more freezing. In contrast, the animals that could avoid the conditioning compartment displayed almost no freezing and exhibited risk assessment responses (i.e., crouch-sniff and stretch postures) and burying behavior. In addition, the animals that were able to avoid the shock chamber had increased Fos expression in the juxtadorsomedial lateral hypothalamic area, the dorsomedial part of the dorsal premammillary nucleus and the lateral and dorsomedial parts of the periaqueductal gray, which are elements of a septo/hippocampal-hypothalamic-brainstem circuit that is putatively involved in mediating contextual avoidance. Overall, the present findings show that testing conditions significantly influence both behavioral responses and the activation of circuits involved in contextual avoidance. PMID:27544875

  17. Intrasensory Redundancy Facilitates Infant Detection of Tempo: Extending Predictions of the Intersensory Redundancy Hypothesis

    PubMed Central

    Bahrick, Lorraine E.; Lickliter, Robert; Castellanos, Irina; Todd, James Torrence

    2015-01-01

    Research has demonstrated that intersensory redundancy (stimulation synchronized across multiple senses) is highly salient and facilitates processing of amodal properties in multimodal events, bootstrapping early perceptual development. The present study is the first to extend this central principle of the intersensory redundancy hypothesis (IRH) to certain types of intrasensory redundancy (stimulation synchronized within a single sense). Infants were habituated to videos of a toy hammer tapping silently (unimodal control), depicting intersensory redundancy (synchronized with a soundtrack) or intrasensory redundancy (synchronized with another visual event; light flashing or bat tapping). In Experiment 1, 2-month-olds showed both intersensory and intrasensory facilitation (with respect to the unimodal control) for detecting a change in tempo. However, intrasensory facilitation was found when the hammer was synchronized with the light flashing (different motion) but not with the bat tapping (same motion). Experiment 2 tested 3-month-olds using a somewhat easier tempo contrast. Results supported a similarity hypothesis: intrasensory redundancy between two dissimilar events was more effective than that between two similar events for promoting processing of amodal properties. These findings extend the IRH and indicate that in addition to intersensory redundancy, intrasensory redundancy between two synchronized dissimilar visual events is also effective in promoting perceptual processing of amodal event properties. PMID:26207101

  18. Micromorphic continua: non-redundant formulations

    NASA Astrophysics Data System (ADS)

    Romano, Giovanni; Barretta, Raffaele; Diaco, Marina

    2016-11-01

    The kinematics of generalized continua is investigated and key points concerning the definition of overall tangent strain measure are put into evidence. It is shown that classical measures adopted in the literature for micromorphic continua do not obey a constraint qualification requirement, to be fulfilled for well-posedness in optimization theory, and are therefore termed redundant. Redundancy of continua with latent microstructure and of constrained Cosserat continua is also assessed. A simplest, non-redundant, kinematic model of micromorphic continua, is proposed by dropping the microcurvature field. The equilibrium conditions and the related variational linear elastostatic problem are formulated and briefly discussed. The simplest model involves a reduced number of state variables and of elastic constitutive coefficients, when compared with other models of micromorphic continua, being still capable of enriching the Cauchy continuum model in a significant way.

  19. Self-Healing Networks: Redundancy and Structure

    PubMed Central

    Quattrociocchi, Walter; Caldarelli, Guido; Scala, Antonio

    2014-01-01

    We introduce the concept of self-healing in the field of complex networks modelling; in particular, self-healing capabilities are implemented through distributed communication protocols that exploit redundant links to recover the connectivity of the system. We then analyze the effect of the level of redundancy on the resilience to multiple failures; in particular, we measure the fraction of nodes still served for increasing levels of network damages. Finally, we study the effects of redundancy under different connectivity patterns—from planar grids, to small-world, up to scale-free networks—on healing performances. Small-world topologies show that introducing some long-range connections in planar grids greatly enhances the resilience to multiple failures with performances comparable to the case of the most resilient (and least realistic) scale-free structures. Obvious applications of self-healing are in the important field of infrastructural networks like gas, power, water, oil distribution systems. PMID:24533065

  20. Redundant single event upset supression system

    DOEpatents

    Hoff, James R.

    2006-04-04

    CMOS transistors are configured to operate as either a redundant, SEU-tolerant, positive-logic, cross-coupled Nor Gate SR-flip flop or a redundant, SEU-tolerant, negative-logic, cross-coupled Nand Gate SR-flip flop. The register can operate as a memory, and further as a memory that can overcome the effects of radiation. As an SR-flip flop, the invention can be altered into any known type of latch or flip-flop by the application of external logic, thereby extending radiation tolerance to devices previously incapable of radiation tolerance. Numerous registers can be logically connected and replicated thereby being electronically configured to operate as a redundant circuit.

  1. Pyrazine analogs are active components of wolf urine that induce avoidance and fear-related behaviors in deer

    PubMed Central

    Osada, Kazumi; Miyazono, Sadaharu; Kashiwayanagi, Makoto

    2014-01-01

    Our previous studies indicated that a cocktail of pyrazine analogs, identified in wolf urine, induced avoidance and fear behaviors in mice. The effects of the pyrazine cocktail on Hokkaido deer (Cervus nippon yesoensis) were investigated in field bioassays at a deer park in Hokkaido, Japan. A set of feeding bioassay trials tested the effects of the pyrazine cocktail odor on the behavior of the deer located around a feeding area in August and September 2013. This odor effectively suppressed the approach of the deer to the feeding area. In addition, the pyrazine cocktail odor provoked fear-related behaviors, such as “tail-flag”, “flight” and “jump” actions, of the deer around the feeding area. This study is the first experimental demonstration that the pyrazine analogs in wolf urine have robust and continual fearful aversive effects on ungulates as well as mice. The pyrazine cocktail might be suitable for a chemical repellent that could limit damage to forests and agricultural crops by wild ungulates. PMID:25177281

  2. Kinematics, controls, and path planning results for a redundant manipulator

    NASA Technical Reports Server (NTRS)

    Gretz, Bruce; Tilley, Scott W.

    1989-01-01

    The inverse kinematics solution, a modal position control algorithm, and path planning results for a 7 degree of freedom manipulator are presented. The redundant arm consists of two links with shoulder and elbow joints and a spherical wrist. The inverse kinematics problem for tip position is solved and the redundant joint is identified. It is also shown that a locus of tip positions exists in which there are kinematic limitations on self-motion. A computationally simple modal position control algorithm has been developed which guarantees a nearly constant closed-loop dynamic response throughout the workspace. If all closed-loop poles are assigned to the same location, the algorithm can be implemented with very little computation. To further reduce the required computation, the modal gains are updated only at discrete time intervals. Criteria are developed for the frequency of these updates. For commanding manipulator movements, a 5th-order spline which minimizes jerk provides a smooth tip-space path. Schemes for deriving a corresponding joint-space trajectory are discussed. Modifying the trajectory to avoid joint torque saturation when a tip payload is added is also considered. Simulation results are presented.

  3. The activation of histamine-sensitive sites of the ventral hippocampus modulates the consolidation of a learned active avoidance response in rats.

    PubMed

    Alvarez, Edgardo O; Banzan, Arturo M

    2008-05-16

    Previous evidence from our laboratory has shown that histamine receptors located into the ventral hippocampus modulate learning and memory processes. Stimulation of histamine hippocampal sensitive receptors during the acquisition phase of a conditioned avoidance response to an ultrasonic tone was able to increase latency to escape and impair memory in the rat. Histamine application into the same hippocampal region also impaired the evocation of the response. The purpose of the present work was to evaluate if histaminergic neuron circuits have participation on the consolidation processes of the conditioned avoiding response. Male adult rats were implanted into the ventral hippocampus with microinjection cannulae and subjected consecutively to 2 sessions of 8 trials to learn an avoidance response after an ultrasonic tone of 40 kHz was on, as it was previously described. Immediately after the training period was over, or 15 min after, different groups of rats were microinjected with saline, histamine or a combination of histamine H(1)- or H(2)-receptor antagonists. Twenty four hours later, animals were tested in a new session for the retention of the avoiding response. Results showed that histamine treatment interfered with the consolidation of the avoiding response, affecting latency and the memory efficiency. This interference was mediated by histamine H(1)- and H(2)-receptors, since pretreatment with pyrilamine or ranitidine blocked the inhibitory effect of histamine. Results support the concept that histaminergic neurotransmission modulates learning and memory by affecting selectively the three stages of learning.

  4. Feasibility of a cognitive behavioural group intervention to reduce fear of falling and associated avoidance of activity in community-living older people: a process evaluation

    PubMed Central

    van Haastregt, Jolanda CM; Zijlstra, GA Rixt; van Rossum, Erik; van Eijk, Jacques ThM; de Witte, Luc P; Kempen, Gertrudis IJM

    2007-01-01

    Background Fear of falling and associated avoidance of activity are common among older people and may have negative consequences in terms of functional decline, quality of life and institutionalisation. We evaluated the effects of a cognitive behavioural group intervention to reduce fear of falling and associated avoidance of activity among older persons. This intervention showed favourable effects on fear of falling, avoidance of activity, daily activity, and several secondary outcomes. The aim of the present study is to assess the feasibility of this cognitive behavioural group intervention for participants and facilitators. Methods The intervention consisted of eight weekly group sessions lasting two hours each and a booster session after six months. Self-administered questionnaires, registration forms and interviews were used to collect data from participants (n = 168) and facilitators (n = 6) on the extent to which the intervention was performed according to protocol, participant attendance, participant adherence, and participants' and facilitators' opinion of the intervention. Quantitative data from the questionnaires and registration forms were analysed by means of descriptive statistics. Qualitative data were categorised based on matching contents of the answers. Results Facilitators reported no major protocol deviations. Twenty-six percent of the participants withdrew before the start of the programme. Of the persons who started the programme, 84% actually completed it. The participants reported their adherence as good, but facilitators had a less favourable opinion of this. The majority of participants still reported substantial benefits from the programme after six and twelve months of follow-up (71% and 61% respectively). Both participants and facilitators provided suggestions for improvement of the intervention. Conclusion Results of this study show that the current cognitive behavioural group intervention is feasible for both participants and

  5. Adaptive Impedance Control Of Redundant Manipulators

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun; Colbaugh, Richard D.; Glass, Kristin L.

    1994-01-01

    Improved method of controlling mechanical impedance of end effector of redundant robotic manipulator based on adaptive-control theory. Consists of two subsystems: adaptive impedance controller generating force-control inputs in Cartesian space of end effector to provide desired end-effector-impedance characteristics, and subsystem implementing algorithm that maps force-control inputs into torques applied to joints of manipulator. Accurate control of end effector and effective utilization of redundancy achieved simultaneously by use of method. Potential use to improve performance of such typical impedance-control tasks as deburring edges and accommodating transitions between unconstrained and constrained motions of end effectors.

  6. Effect of radicicol infusion on the Src tyrosine kinase activity of rat hippocampus before and after training in an inhibitory avoidance task.

    PubMed

    Pereira, Patrícia; Vinadé, Elsa; Rodrigues, Letícia; De David e Silva, Tiago L; Ardenghi, Patrícia; da Silva Brum, Lucimar Filot; Gonçalves, Carlos Alberto; Izquierdo, Iván

    2007-07-01

    The participation of protein serine/threonine kinases in memory formation and retrieval is well established. In contrast, relatively little is known on the role of protein tyrosine kinases (PTKs). Previous work showed that intra-hippocampal infusion of the Src-PTK inhibitor radicicol inhibits memory acquisition, consolidation, and retrieval of one-trial step-down inhibitory avoidance task. In this study, we investigated the possible interaction between levels of Src-PTK activity in hippocampus and memory acquisition, formation, and retrieval of this task. Radicicol (0.5 microg/ml) was infused into the CA1 region of the hippocampus of rats trained in a one-trial step-down inhibitory avoidance task. Radicicol infused 15 min before training decreased Src-PTK activity, as measured 0, 1.5, and 24 h after training, and impaired memory acquisition of the task. When given immediately after training, there was a decrease in Src-PTK activity 1.5 h, but not 0 or 24 h after training. This treatment depressed memory consolidation. Radicicol infused into CA1 10 min prior to retrieval testing inhibited hippocampal Src-PTK activity, as measured immediately after the test session. The results suggest that Src-PTKs participate in memory acquisition, consolidation, and retrieval processes, but the timing of the role of the enzyme is different in each case.

  7. High Correlation of 2,2-diphenyl-1-picrylhydrazyl (DPPH) Radical Scavenging, Ferric Reducing Activity Potential and Total Phenolics Content Indicates Redundancy in Use of All Three Assays to Screen for Antioxidant Activity of Extracts of Plants from the Malaysian Rainforest

    PubMed Central

    Clarke, Garry; Ting, Kang Nee; Wiart, Christophe; Fry, Jeffrey

    2013-01-01

    Extracts of plants from the Malaysian rainforest and other fragile habitats are being researched intensively for identification of beneficial biological actions, with assessment of antioxidant behavior being a common component of such assessments. A number of tests for antioxidant behavior are used, with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reduction activity potential (FRAP) assays often being used in parallel, and also with measurement of total phenolics content (TPC) as a surrogate marker for antioxidant capacity. The present study investigated the possible redundancy in using all three assays to determine antioxidant capacity in 92 extracts obtained from 27 plants from the Malaysian rainforest. The results demonstrated that the assays displayed a high (R ≥ 0.82) and significant (P < 0.0001) correlation with one another, indicating a high level of redundancy if all three assays are used in parallel. This appears to be a waste of potentially valuable plant extracts. Because of problems with the FRAP assay relating to color interference and variable rates of reaction point, the DPPH assay is the preferred assay in preliminary screening of extracts of plants from the Malaysian rainforest. PMID:26787618

  8. Analysis of informational redundancy in the protein-assembling machinery

    NASA Astrophysics Data System (ADS)

    Berkovich, Simon

    2004-03-01

    Entropy analysis of the DNA structure does not reveal a significant departure from randomness indicating lack of informational redundancy. This signifies the absence of a hidden meaning in the genome text and supports the 'barcode' interpretation of DNA given in [1]. Lack of informational redundancy is a characteristic property of an identification label rather than of a message of instructions. Yet randomness of DNA has to induce non-random structures of the proteins. Protein synthesis is a two-step process: transcription into RNA with gene splicing and formation a structure of amino acids. Entropy estimations, performed by A. Djebbari, show typical values of redundancy of the biomolecules along these pathways: DNA gene 4proteins 15-40in gene expression, the RNA copy carries the same information as the original DNA template. Randomness is essentially eliminated only at the step of the protein creation by a degenerate code. According to [1], the significance of the substitution of U for T with a subsequent gene splicing is that these transformations result in a different pattern of RNA oscillations, so the vital DNA communications are protected against extraneous noise coming from the protein making activities. 1. S. Berkovich, "On the 'barcode' functionality of DNA, or the Phenomenon of Life in the Physical Universe", Dorrance Publishing Co., Pittsburgh, 2003

  9. Motion planning for redundant prismatic-jointed manipulators in the free-floating mode

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Dong; Baoyin, He-Xi; Ma, Xing-Rui

    2012-10-01

    This paper investigates the motion planning of redundant free-floating manipulators with seven prismatic joints. On the earth, prismatic-jointed manipulators could only position their end-effectors in a desired way. However, in space, the end-effectors of free-floating manipulators can achieve both the desired orientation and desired position due to the dynamical coupling between manipulator and satellite movement, which is formally expressed by linear and angular momentum conservation laws. In this study, a tractable algorithm particle swarm optimization combined with differential evolution (PSODE) is provided to deal with the motion planning of redundant free-floating prismatic-jointed manipulators, which could avoid the pseudo inverse of the Jacobian matrix. The polynomial functions, as argument in sine functions are used to specify the joint paths. The coefficients of the polynomials are optimized to achieve the desired end-effector orientation and position, and simultaneously minimize the unit-mass-kinetic energy using the redundancy. Relevant simulations prove that this method provides satisfactory smooth paths for redundant free-floating prismatic-jointed manipulators. This study could help to recognize the advantages of redundant prismatic-jointed space manipulators.

  10. An improved method for calculating self-motion coordinates for redundant manipulators

    SciTech Connect

    Reister, D.B.

    1997-04-01

    For a redundant manipulator, the objective of redundancy resolution is to follow a specified path in Cartesian space and simultaneously perform another task (for example, maximize an objective function or avoid obstacles) at every point along the path. The conventional methods have several drawbacks: a new function must be defined for each task, the extended Jacobian can be singular, closed cycles in Cartesian space may not yield closed cycles in joint space, and the objective is point-wise redundancy resolution (to determine a single point in joint space for each point in Cartesian space). The author divides the redundancy resolution problem into two parts: (1) calculate self-motion coordinates for all possible positions of a manipulator at each point along a Cartesian path and (2) determination of optimal self-motion coordinates that maximize an objective function along the path. This paper will discuss the first part of the problem. The path-wise approach overcomes all of the drawbacks of conventional redundancy resolution methods: no need to define a new function for each task, extended Jacobian cannot be singular, and closed cycles in extended Cartesian space will yield closed cycles in joint space.

  11. Local performance optimization for a class of redundant eight-degree-of-freedom manipulators

    NASA Technical Reports Server (NTRS)

    Williams, Robert L., II

    1994-01-01

    Local performance optimization for joint limit avoidance and manipulability maximization (singularity avoidance) is obtained by using the Jacobian matrix pseudoinverse and by projecting the gradient of an objective function into the Jacobian null space. Real-time redundancy optimization control is achieved for an eight-joint redundant manipulator having a three-axis spherical shoulder, a single elbow joint, and a four-axis spherical wrist. Symbolic solutions are used for both full-Jacobian and wrist-partitioned pseudoinverses, partitioned null-space projection matrices, and all objective function gradients. A kinematic limitation of this class of manipulators and the limitation's effect on redundancy resolution are discussed. Results obtained with graphical simulation are presented to demonstrate the effectiveness of local redundant manipulator performance optimization. Actual hardware experiments performed to verify the simulated results are also discussed. A major result is that the partitioned solution is desirable because of low computation requirements. The partitioned solution is suboptimal compared with the full solution because translational and rotational terms are optimized separately; however, the results show that the difference is not significant. Singularity analysis reveals that no algorithmic singularities exist for the partitioned solution. The partitioned and full solutions share the same physical manipulator singular conditions. When compared with the full solution, the partitioned solution is shown to be ill-conditioned in smaller neighborhoods of the shared singularities.

  12. Light-avoidance-mediating photoreceptors tile the Drosophila larval body wall.

    PubMed

    Xiang, Yang; Yuan, Quan; Vogt, Nina; Looger, Loren L; Jan, Lily Yeh; Jan, Yuh Nung

    2010-12-16

    Photoreceptors for visual perception, phototaxis or light avoidance are typically clustered in eyes or related structures such as the Bolwig organ of Drosophila larvae. Unexpectedly, we found that the class IV dendritic arborization neurons of Drosophila melanogaster larvae respond to ultraviolet, violet and blue light, and are major mediators of light avoidance, particularly at high intensities. These class IV dendritic arborization neurons, which are present in every body segment, have dendrites tiling the larval body wall nearly completely without redundancy. Dendritic illumination activates class IV dendritic arborization neurons. These novel photoreceptors use phototransduction machinery distinct from other photoreceptors in Drosophila and enable larvae to sense light exposure over their entire bodies and move out of danger.

  13. Intersensory Redundancy Accelerates Preverbal Numerical Competence

    ERIC Educational Resources Information Center

    Jordan, Kerry E.; Suanda, Sumarga H.; Brannon, Elizabeth M.

    2008-01-01

    Intersensory redundancy can facilitate animal and human behavior in areas as diverse as rhythm discrimination, signal detection, orienting responses, maternal call learning, and associative learning. In the realm of numerical development, infants show similar sensitivity to numerical differences in both the visual and auditory modalities. Using a…

  14. Redundant Array Configurations for 21 cm Cosmology

    NASA Astrophysics Data System (ADS)

    Dillon, Joshua S.; Parsons, Aaron R.

    2016-08-01

    Realizing the potential of 21 cm tomography to statistically probe the intergalactic medium before and during the Epoch of Reionization requires large telescopes and precise control of systematics. Next-generation telescopes are now being designed and built to meet these challenges, drawing lessons from first-generation experiments that showed the benefits of densely packed, highly redundant arrays—in which the same mode on the sky is sampled by many antenna pairs—for achieving high sensitivity, precise calibration, and robust foreground mitigation. In this work, we focus on the Hydrogen Epoch of Reionization Array (HERA) as an interferometer with a dense, redundant core designed following these lessons to be optimized for 21 cm cosmology. We show how modestly supplementing or modifying a compact design like HERA’s can still deliver high sensitivity while enhancing strategies for calibration and foreground mitigation. In particular, we compare the imaging capability of several array configurations, both instantaneously (to address instrumental and ionospheric effects) and with rotation synthesis (for foreground removal). We also examine the effects that configuration has on calibratability using instantaneous redundancy. We find that improved imaging with sub-aperture sampling via “off-grid” antennas and increased angular resolution via far-flung “outrigger” antennas is possible with a redundantly calibratable array configuration.

  15. Impact Of Redundancy On Undersea Lightwave Systems

    NASA Astrophysics Data System (ADS)

    Brewer, S. Theodore

    1990-01-01

    Undersea lightwave systems represent a fascinating and challenging application of photonics engineering. Economy, transmission quality and long-term reliability are the hallmarks of these new systems. The optical fiber medium offers very high channel capacity for voice and all other digitally encoded signals. The high capacity results in low cost per channel. Concerning transmission quality, today digital transmission on undersea cables carries signals halfway round the world with quiet, virtually error - free performance. Furthermore, the short, direct path of the undersea route minimizes signal delay, making a significant contribution to customer satisfaction with voice, data, video conferencing, and other interactive services. We needed to achieve these important advances in economy and quality of transmission, and yet deliver systems with the traditional 25 year life and high reliability. This was the dilemma, to achieve extraordinarily high reliability with technologies which lacked extensive high-reliability background. Redundancy in several forms allowed us to introduce this advanced technology with high confidence of meeting the goal of 25 years of reliable system service. Following some historical notes on undersea cables, we describe the forms and levels of redundancy used in AT&T's SL Undersea cable systems. We then indicate how redundancy was implemented and it's impact on system reliability. Finally, we do a bit of crystal gazing concerning redundancy and reliability in the rapidly evolving optical undersea cable network.

  16. Britain's Redundancy Payments for Displaced Workers.

    ERIC Educational Resources Information Center

    Root, Lawrence S.

    1987-01-01

    The Redundancy Payments Act of 1965 established the idea that an employee has property rights to a job based on years of company service. It instituted an entitlement program for displaced workers sponsored by firms and the government. The British layoff situtation differs from that of the United States. (Author/CH)

  17. Species of Redundancy in Visual Target Detection

    ERIC Educational Resources Information Center

    Ben-David, Boaz M.; Algom, Daniel

    2009-01-01

    We report a series of investigations into the effects of common names, physical identity, and physical similarity on visual detection time. The effect of these factors on the capacity of the system processing the signals was also examined. We used a redundant targets design with separate testing of the target-distractor (single target),…

  18. Avoiding Infusion Confusion 7th through 9th Grades. A Practical Handbook for Infusing Environmental Activities into Your Classroom.

    ERIC Educational Resources Information Center

    Hayden, Harvey; And Others

    To some educators, infusing environmental education into different subject areas at different levels may seem like an insurmountable task. This handbook was developed to take the guesswork out of this process and alleviate the fear and confusion that may result. It was designed to assist with infusing knowledge, skill and attitude activities into…

  19. Required attention for synthesized speech perception for three levels of linguistic redundancy

    NASA Technical Reports Server (NTRS)

    Simpson, C. A.; Hart, S. G.

    1977-01-01

    The study evaluates the attention required for synthesized speech perception with reference to three levels of linguistic redundancy. Twelve commercial airline pilots were individually tested for 16 cockpit warning messages eight of which consisted of two monosyllabic key words and eight of which consisted of two polysyllabic key words. Three levels of linguistic redundancy were identified: monosyllabic words, polysyllabic words, and sentences. The experiment contained a message familiarization phase and a message recognition phase. It was found that: (1) when the messages are part of a previously learned and recently heard set, and the subject is familiar with the phrasing, the attention needed to recognize the message is not a function of the level of linguistic redundancy, and (2) there is a quantitative and qualitative difference between recognition and comprehension processes; only in the case of active comprehension does additional redundancy reduce attention requirements.

  20. Practical, redundant, failure-tolerant, self-reconfiguring embedded system architecture

    DOEpatents

    Klarer, Paul R.; Hayward, David R.; Amai, Wendy A.

    2006-10-03

    This invention relates to system architectures, specifically failure-tolerant and self-reconfiguring embedded system architectures. The invention provides both a method and architecture for redundancy. There can be redundancy in both software and hardware for multiple levels of redundancy. The invention provides a self-reconfiguring architecture for activating redundant modules whenever other modules fail. The architecture comprises: a communication backbone connected to two or more processors and software modules running on each of the processors. Each software module runs on one processor and resides on one or more of the other processors to be available as a backup module in the event of failure. Each module and backup module reports its status over the communication backbone. If a primary module does not report, its backup module takes over its function. If the primary module becomes available again, the backup module returns to its backup status.

  1. Unpredictable chronic stress decreases inhibitory avoidance learning in Tuebingen long-fin zebrafish: stronger effects in the resting phase than in the active phase.

    PubMed

    Manuel, Remy; Gorissen, Marnix; Zethof, Jan; Ebbesson, Lars O E; van de Vis, Hans; Flik, Gert; van den Bos, Ruud

    2014-11-01

    Zebrafish (Danio rerio Hamilton) are increasingly used as a model to study the effects of chronic stress on brain and behaviour. In rodents, unpredictable chronic stress (UCS) has a stronger effect on physiology and behaviour during the active phase than during the resting phase. Here, we applied UCS during the daytime (active phase) for 7 and 14 days or during the night-time (resting phase) for 7 nights in an in-house-reared Tuebingen long-fin (TLF) zebrafish strain. Following UCS, inhibitory avoidance learning was assessed using a 3 day protocol where fish learn to avoid swimming from a white to a black compartment where they will receive a 3 V shock. Latencies of entering the black compartment were recorded before training (day 1; first shock) and after training on day 2 (second shock) and day 3 (no shock, tissue sampling). Fish whole-body cortisol content and expression levels of genes related to stress, fear and anxiety in the telencephalon were quantified. Following 14 days of UCS during the day, inhibitory avoidance learning decreased (lower latencies on days 2 and 3); minor effects were found following 7 days of UCS. Following 7 nights of UCS, inhibitory avoidance learning decreased (lower latency on day 3). Whole-body cortisol levels showed a steady increase compared with controls (100%) from 7 days of UCS (139%), to 14 days of UCS (174%) to 7 nights of UCS (231%), suggestive of an increasing stress load. Only in the 7 nights of UCS group did expression levels of corticoid receptor genes (mr, grα, grβ) and of bdnf increase. These changes are discussed as adaptive mechanisms to maintain neuronal integrity and prevent overload, and as being indicative of a state of high stress load. Overall, our data suggest that stressors during the resting phase have a stronger impact than during the active phase. Our data warrant further studies on the effect of UCS on stress axis-related genes, especially grβ; in mammals this receptor has been implicated in

  2. [Effects of activation and blockade of dopamine receptors on extinction of passive avoidance response in mice with depressive-like state].

    PubMed

    Dubrovina, N I; Zinov'eva, D V

    2008-01-01

    Selectivity of training and extinction of passive avoidance response caused by pharmacological influences on D1 and D2 dopamine receptors in intact mice and mice in depressive-like state was shown. Training was impaired only by administration of D2 receptor antagonist sulpiride and did not depend on the initial functional condition of mice. In intact mice, activation of D2 receptors by quinpirole evoked deficiency of extinction, i.e., impairment of the capability of new inhibitory training under conditions of disappearance of the expected punishment. In mice with reaction of "behavioral despair" characterized by a delay of extinction, activation of D1 receptors by SKF38393 normalized this process (as distinct from the inefficiency of D2 agonist). The positive effect of acceleration of fear memory extinction was revealed also under conditions of blockade of D1 and D2 dopamine receptors. PMID:19004320

  3. Effects of activation and blockade of dopamine receptors on the extinction of a passive avoidance reaction in mice with a depressive-like state.

    PubMed

    Dubrovina, N I; Zinov'eva, D V

    2010-01-01

    Learning and extinction of a conditioned passive avoidance reaction resulting from neuropharmacological actions on dopamine D(1) and D(2) receptors were demonstrated to be specific in intact mice and in mice with a depressive-like state. Learning was degraded only after administration of the D(2) receptor antagonist sulpiride and was independent of the initial functional state of the mice. In intact mice, activation of D(2) receptors with quinpirole led to a deficit of extinction, consisting of a reduction in the ability to acquire new inhibitory learning in conditions associated with the disappearance of the expected punishment. In mice with the "behavioral despair" reaction, characterized by delayed extinction, activation of D(1) receptors with SKF38393 normalized this process, while the D(2) agonist was ineffective. A positive effect consisting of accelerated extinction of the memory of fear of the dark ("dangerous") sector of the experimental chamber was also seen on blockade of both types of dopamine receptor. PMID:20012492

  4. Effects of activation and blockade of dopamine receptors on the extinction of a passive avoidance reaction in mice with a depressive-like state.

    PubMed

    Dubrovina, N I; Zinov'eva, D V

    2010-01-01

    Learning and extinction of a conditioned passive avoidance reaction resulting from neuropharmacological actions on dopamine D(1) and D(2) receptors were demonstrated to be specific in intact mice and in mice with a depressive-like state. Learning was degraded only after administration of the D(2) receptor antagonist sulpiride and was independent of the initial functional state of the mice. In intact mice, activation of D(2) receptors with quinpirole led to a deficit of extinction, consisting of a reduction in the ability to acquire new inhibitory learning in conditions associated with the disappearance of the expected punishment. In mice with the "behavioral despair" reaction, characterized by delayed extinction, activation of D(1) receptors with SKF38393 normalized this process, while the D(2) agonist was ineffective. A positive effect consisting of accelerated extinction of the memory of fear of the dark ("dangerous") sector of the experimental chamber was also seen on blockade of both types of dopamine receptor.

  5. [Effects of activation and blockade of dopamine receptors on extinction of passive avoidance response in mice with depressive-like state].

    PubMed

    Dubrovina, N I; Zinov'eva, D V

    2008-01-01

    Selectivity of training and extinction of passive avoidance response caused by pharmacological influences on D1 and D2 dopamine receptors in intact mice and mice in depressive-like state was shown. Training was impaired only by administration of D2 receptor antagonist sulpiride and did not depend on the initial functional condition of mice. In intact mice, activation of D2 receptors by quinpirole evoked deficiency of extinction, i.e., impairment of the capability of new inhibitory training under conditions of disappearance of the expected punishment. In mice with reaction of "behavioral despair" characterized by a delay of extinction, activation of D1 receptors by SKF38393 normalized this process (as distinct from the inefficiency of D2 agonist). The positive effect of acceleration of fear memory extinction was revealed also under conditions of blockade of D1 and D2 dopamine receptors.

  6. Avoiding the Flu

    MedlinePlus

    ... of this page please turn Javascript on. Feature: Flu Avoiding the Flu Past Issues / Fall 2009 Table of Contents Children ... help avoid getting and passing on the flu. Influenza (Seasonal) The flu is a contagious respiratory illness ...

  7. Synergy, redundancy and unnormalized Granger causality.

    PubMed

    Stramaglia, S; Angelini, L; Cortes, J M; Marinazzo, D

    2015-08-01

    We analyze by means of Granger causality the effect of synergy and redundancy in the inference (from time series data) of the information flow between subsystems of a complex network. Whilst fully conditioned Granger causality is not affected by synergy, the pairwise analysis fails to put in evidence synergetic effects. We show that maximization of the total Granger causality to a given target, over all the possible partitions of the set of driving variables, puts in evidence redundant multiplets of variables influencing the target, provided that an unnormalized definition of Granger causality is adopted. Along the same lines we also introduce a pairwise index of synergy (w.r.t. to information flow to a third variable) which is zero when two independent sources additively influence a common target; thus, this definition differs from previous definitions of synergy.

  8. Consistent inter‐individual differences in common marmosets (Callithrix jacchus) in Boldness‐Shyness, Stress‐Activity, and Exploration‐Avoidance

    PubMed Central

    Gunhold‐de Oliveira, Tina; Tadić, Zoran; Massen, Jorg J.M.; Bugnyar, Thomas

    2016-01-01

    The study of animal personality, defined as consistent inter‐individual differences in correlated behavioral traits stable throughout time and/or contexts, has recently become one of the fastest growing areas in animal biology, with study species ranging from insects to non‐human primates. The latter have, however, only occasionally been tested with standardized experiments. Instead their personality has usually been assessed using questionnaires. Therefore, this study aimed to test 21 common marmosets (Callithrix jacchus) living in three family groups, in five different experiments, and their corresponding controls. We found that behavioral differences between our animals were not only consistent over time, but also across different contexts. Moreover, the consistent behaviors formed a construct of four major non‐social personality components: Boldness‐Shyness in Foraging, Boldness‐Shyness in Predation, Stress‐Activity, and Exploration‐Avoidance. We found no sex or age differences in these components, but our results did reveal differences in Exploration‐Avoidance between the three family groups. As social environment can have a large influence on behavior of individuals, our results may suggest group‐level similarity in personality (i.e., “group personality”) in common marmosets, a species living in highly cohesive social groups. Am. J. Primatol. 78:961–973, 2016. © 2016 The Authors. American Journal of Primatology published by Wiley Periodicals, Inc. PMID:27286098

  9. A highly redundant robot system for inspection

    NASA Technical Reports Server (NTRS)

    Lee, Thomas S.; Ohms, Tim; Hayati, Samad

    1994-01-01

    The work on the serpentine inspection system at JPL is described. The configuration of the inspection system consists of 20 degrees of freedom in total. In particular, the design and development of the serpentine micromanipulator end-effector tool which has 12 degrees of freedom is described. The inspection system is used for application in JPL's Remote Surface Inspection project and as a research tool in redundant manipulator control.

  10. Dual redundant display in bubble canopy applications

    NASA Astrophysics Data System (ADS)

    Mahdi, Ken; Niemczyk, James

    2010-04-01

    Today's cockpit integrator, whether for state of the art military fast jet, or piston powered general aviation, is striving to utilize all available panel space for AMLCD based displays to enhance situational awareness and increase safety. The benefits of a glass cockpit have been well studied and documented. The technology used to create these glass cockpits, however, is driven by commercial AMLCD demand which far outstrips the combined worldwide avionics requirements. In order to satisfy the wide variety of human factors and environmental requirements, large area displays have been developed to maximize the usable display area while also providing necessary redundancy in case of failure. The AMLCD has been optimized for extremely wide viewing angles driven by the flat panel TV market. In some cockpit applications, wide viewing cones are desired. In bubble canopy cockpits, however, narrow viewing cones are desired to reduce canopy reflections. American Panel Corporation has developed AMLCD displays that maximize viewing area, provide redundancy, while also providing a very narrow viewing cone even though commercial AMLCD technology is employed suitable for high performance AMLCD Displays. This paper investigates both the large area display architecture with several available options to solve redundancy as well as beam steering techniques to also limit canopy reflections.

  11. Redundant causation from a sufficient cause perspective.

    PubMed

    Gatto, Nicolle M; Campbell, Ulka B

    2010-08-02

    Sufficient causes of disease are redundant when an individual acquires the components of two or more sufficient causes. In this circumstance, the individual still would have become diseased even if one of the sufficient causes had not been acquired. In the context of a study, when any individuals acquire components of more than one sufficient cause over the observation period, the etiologic effect of the exposure (defined as the absolute or relative difference between the proportion of the exposed who develop the disease by the end of the study period and the proportion of those individuals who would have developed the disease at the moment they did even in the absence of the exposure) may be underestimated. Even in the absence of confounding and bias, the observed effect estimate represents only a subset of the etiologic effect. This underestimation occurs regardless of the measure of effect used.To some extent, redundancy of sufficient causes is always present, and under some circumstances, it may make a true cause of disease appear to be not causal. This problem is particularly relevant when the researcher's goal is to characterize the universe of sufficient causes of the disease, identify risk factors for targeted interventions, or construct causal diagrams. In this paper, we use the sufficient component cause model and the disease response type framework to show how redundant causation arises and the factors that determine the extent of its impact on epidemiologic effect measures.

  12. Redundant causation from a sufficient cause perspective.

    PubMed

    Gatto, Nicolle M; Campbell, Ulka B

    2010-01-01

    Sufficient causes of disease are redundant when an individual acquires the components of two or more sufficient causes. In this circumstance, the individual still would have become diseased even if one of the sufficient causes had not been acquired. In the context of a study, when any individuals acquire components of more than one sufficient cause over the observation period, the etiologic effect of the exposure (defined as the absolute or relative difference between the proportion of the exposed who develop the disease by the end of the study period and the proportion of those individuals who would have developed the disease at the moment they did even in the absence of the exposure) may be underestimated. Even in the absence of confounding and bias, the observed effect estimate represents only a subset of the etiologic effect. This underestimation occurs regardless of the measure of effect used.To some extent, redundancy of sufficient causes is always present, and under some circumstances, it may make a true cause of disease appear to be not causal. This problem is particularly relevant when the researcher's goal is to characterize the universe of sufficient causes of the disease, identify risk factors for targeted interventions, or construct causal diagrams. In this paper, we use the sufficient component cause model and the disease response type framework to show how redundant causation arises and the factors that determine the extent of its impact on epidemiologic effect measures. PMID:20678223

  13. Regularized Partial and/or Constrained Redundancy Analysis

    ERIC Educational Resources Information Center

    Takane, Yoshio; Jung, Sunho

    2008-01-01

    Methods of incorporating a ridge type of regularization into partial redundancy analysis (PRA), constrained redundancy analysis (CRA), and partial and constrained redundancy analysis (PCRA) were discussed. The usefulness of ridge estimation in reducing mean square error (MSE) has been recognized in multiple regression analysis for some time,…

  14. Nonlinear Redundancy Analysis. Research Report 88-1.

    ERIC Educational Resources Information Center

    van der Burg, Eeke; de Leeuw, Jan

    A non-linear version of redundancy analysis is introduced. The technique is called REDUNDALS. It is implemented within the computer program for canonical correlation analysis called CANALS. The REDUNDALS algorithm is of an alternating least square (ALS) type. The technique is defined as minimization of a squared distance between criterion…

  15. Intersensory Redundancy Enhances Memory in Bobwhite Quail Embryos

    ERIC Educational Resources Information Center

    Lickliter, Robert; Bahrick, Lorraine E.; Honeycutt, Hunter

    2004-01-01

    Information presented concurrently and redundantly to 2 or more senses (intersensory redundancy) has been shown to recruit attention and promote perceptual learning of amodal stimulus properties in animal embryos and human infants. This study examined whether the facilitative effect of intersensory redundancy also extends to the domain of memory.…

  16. Multiple redundant medulla projection neurons mediate color vision in Drosophila.

    PubMed

    Melnattur, Krishna V; Pursley, Randall; Lin, Tzu-Yang; Ting, Chun-Yuan; Smith, Paul D; Pohida, Thomas; Lee, Chi-Hon

    2014-01-01

    The receptor mechanism for color vision has been extensively studied. In contrast, the circuit(s) that transform(s) photoreceptor signals into color percepts to guide behavior remain(s) poorly characterized. Using intersectional genetics to inactivate identified subsets of neurons, we have uncovered the first-order interneurons that are functionally required for hue discrimination in Drosophila. We developed a novel aversive operant conditioning assay for intensity-independent color discrimination (true color vision) in Drosophila. Single flying flies are magnetically tethered in an arena surrounded by blue and green LEDs (light-emitting diodes). The flies' optomotor response is used to determine the blue-green isoluminant intensity. Flies are then conditioned to discriminate between equiluminant blue or green stimuli. Wild-type flies are successfully trained in this paradigm when conditioned to avoid either blue or green. Functional color entrainment requires the function of the narrow-spectrum photoreceptors R8 and/or R7, and is within a limited range, intensity independent, suggesting that it is mediated by a color vision system. The medulla projection neurons, Tm5a/b/c and Tm20, receive direct inputs from R7 or R8 photoreceptors and indirect input from the broad-spectrum photoreceptors R1-R6 via the lamina neuron L3. Genetically inactivating these four classes of medulla projection neurons abolished color learning. However, inactivation of subsets of these neurons is insufficient to block color learning, suggesting that true color vision is mediated by multiple redundant pathways. We hypothesize that flies represent color along multiple axes at the first synapse in the fly visual system. The apparent redundancy in learned color discrimination sharply contrasts with innate ultraviolet (UV) spectral preference, which is dominated by a single pathway from the amacrine neuron Dm8 to the Tm5c projection neurons. PMID:24766346

  17. Multiple redundant medulla projection neurons mediate color vision in Drosophila.

    PubMed

    Melnattur, Krishna V; Pursley, Randall; Lin, Tzu-Yang; Ting, Chun-Yuan; Smith, Paul D; Pohida, Thomas; Lee, Chi-Hon

    2014-01-01

    The receptor mechanism for color vision has been extensively studied. In contrast, the circuit(s) that transform(s) photoreceptor signals into color percepts to guide behavior remain(s) poorly characterized. Using intersectional genetics to inactivate identified subsets of neurons, we have uncovered the first-order interneurons that are functionally required for hue discrimination in Drosophila. We developed a novel aversive operant conditioning assay for intensity-independent color discrimination (true color vision) in Drosophila. Single flying flies are magnetically tethered in an arena surrounded by blue and green LEDs (light-emitting diodes). The flies' optomotor response is used to determine the blue-green isoluminant intensity. Flies are then conditioned to discriminate between equiluminant blue or green stimuli. Wild-type flies are successfully trained in this paradigm when conditioned to avoid either blue or green. Functional color entrainment requires the function of the narrow-spectrum photoreceptors R8 and/or R7, and is within a limited range, intensity independent, suggesting that it is mediated by a color vision system. The medulla projection neurons, Tm5a/b/c and Tm20, receive direct inputs from R7 or R8 photoreceptors and indirect input from the broad-spectrum photoreceptors R1-R6 via the lamina neuron L3. Genetically inactivating these four classes of medulla projection neurons abolished color learning. However, inactivation of subsets of these neurons is insufficient to block color learning, suggesting that true color vision is mediated by multiple redundant pathways. We hypothesize that flies represent color along multiple axes at the first synapse in the fly visual system. The apparent redundancy in learned color discrimination sharply contrasts with innate ultraviolet (UV) spectral preference, which is dominated by a single pathway from the amacrine neuron Dm8 to the Tm5c projection neurons.

  18. Maximization of Learning Speed Due to Neuronal Redundancy in Reinforcement Learning

    NASA Astrophysics Data System (ADS)

    Takiyama, Ken

    2016-11-01

    Adaptable neural activity contributes to the flexibility of human behavior, which is optimized in situations such as motor learning and decision making. Although learning signals in motor learning and decision making are low-dimensional, neural activity, which is very high dimensional, must be modified to achieve optimal performance based on the low-dimensional signal, resulting in a severe credit-assignment problem. Despite this problem, the human brain contains a vast number of neurons, leaving an open question: what is the functional significance of the huge number of neurons? Here, I address this question by analyzing a redundant neural network with a reinforcement-learning algorithm in which the numbers of neurons and output units are N and M, respectively. Because many combinations of neural activity can generate the same output under the condition of N ≫ M, I refer to the index N - M as neuronal redundancy. Although greater neuronal redundancy makes the credit-assignment problem more severe, I demonstrate that a greater degree of neuronal redundancy facilitates learning speed. Thus, in an apparent contradiction of the credit-assignment problem, I propose the hypothesis that a functional role of a huge number of neurons or a huge degree of neuronal redundancy is to facilitate learning speed.

  19. Visualization of redundancy resolution for kinematically redundant robots through the Jacobian null space

    NASA Technical Reports Server (NTRS)

    Chen, Yu-Che; Walker, Ian D.; Cheatham, John B., Jr.

    1992-01-01

    We present a unified formulation for the inverse kinematics of redundant arms, based on a special formulation of the null space of the Jacobian. By extending (appropriately re-scaling) previously used null space parameterizations, we obtain, in a unified fashion, the manipulability measure, the null space projector, and particular solutions for the joint velocities. We obtain the minimum norm pseudo-inverse solution as a projection from any particular solution, and the method provides an intuitive visualization of the self-motion. The result is a computationally efficient, consistent approach to computing redundant robot inverse kinematics.

  20. Factor affecting the endogenous β-glucuronidase activity in rapeseed haploid cells: how to avoid interference with the Gus transgene in transformation studies.

    PubMed

    Abdollahi, M R; Memari, H Rajabi; van Wijnen, A J

    2011-11-01

    The gus gene is one of the most frequently used reporter genes in transgenic plants. However, this gene can only be used if the selected plant species does not show endogenous GUS activity. Rapeseed (Brassica napus) microspores and microspore-derived embryos (MDEs) were found to exhibit high activity of endogenous β-glucuronidase which interferes with the expression of bacterial β-glucuronidase that was transferred into these tissues by biolistic transformation. In order to eliminate this background activity from rapeseed MDEs, different pHs of the assay buffer (5.8, 7 and 8) with or without methanol in the reaction buffer and incubation of these tissues at different temperatures (24°C, 38°C and 55°C) were investigated. To avoid this problem in microspores, two incubation temperatures (38°C and 55°C) at different periods after GUS assay (4, 24 and 48h) and in the presence of 1mM potassium ferricyanide and 1mM potassium ferrocyanide were tested. The endogenous GUS activity was significantly decreased in transformed and untransformed MDEs, when the phosphate buffer was adjusted to pH 8 and 28% methanol in the reaction solution was used. In rapeseed microspores, use of 1mM potassium ferricyanide and 1mM potassium ferrocyanide in the reaction buffer enhanced the expression rate of gus transgene rather than endogenous GUS activity where the high levels of gus transgene expression was observed 4h after histochemical GUS assay. Incubation of rapeseed microspores and MDEs at 55°C completely eliminated the endogenous GUS activity. In this study, we also examined changes in endogenous GUS activity in rapeseed MDEs at several stages including the globular, heart, torpedo and cotyledonary stages. The level of endogenous GUS activity was increased 4.33 folds in heart embryos, 6.54 folds in torpedo embryos and 8.5 folds in cotyledonary embryos. Furthermore, the level of GUS activity increased 1.72 folds in MDEs of B. napus in 12-h treatment with 2μM gibberellic acid

  1. Dose-dependent impairment of inhibitory avoidance retention in rats by immediate post-training infusion of a mitogen-activated protein kinase kinase inhibitor into cortical structures.

    PubMed

    Walz, R; Roesler, R; Quevedo, J; Rockenbach, I C; Amaral, O B; Vianna, M R; Lenz, G; Medina, J H; Izquierdo, I

    1999-11-15

    Mitogen-activated protein kinase (MAPK) is a serine/threonine protein kinase abundantly expressed in postmitotic neurons of the developed nervous system. MAPK is activated in and required for both the induction of long-term potentiation (LTP) in hippocampal slices and the acquisition of fear conditioning training in rats. The present work was performed in order to test the effect of the specific inhibitor of MAPK kinase (MAPKK), PD 098059, on retention of a step-down inhibitory avoidance (IA). Adult male Wistar rats were bilaterally injected (0.5 microl/side) with PD 098059 (at 0.5, 5, or 50 microM) or vehicle into the entorhinal cortex or into the parietal cortex immediately after IA training using a 0.4 mA footshock. Retention testing was carried out 24 h after training. PD 098059 impaired retention when injected into the entorhinal cortex at the dose of 50 microM, but not at the doses of 5 or 0.5 microM. When infused into the parietal cortex, PD 098059 was amnestic at the doses of 5 and 50 microM. The drug had no effect when infused at the highest dose in either structure 6 h after training. Our results suggest that the MAPKK inhibitor impairs IA retention memory in a dose-dependent manner when injected immediately after training into entorhinal cortex or parietal cortex. The effective dose is variable according to the neocortical structure studied.

  2. Avoiding Statistical Mistakes

    ERIC Educational Resources Information Center

    Strasser, Nora

    2007-01-01

    Avoiding statistical mistakes is important for educators at all levels. Basic concepts will help you to avoid making mistakes using statistics and to look at data with a critical eye. Statistical data is used at educational institutions for many purposes. It can be used to support budget requests, changes in educational philosophy, changes to…

  3. Increased Physical Activity and Fitness above the 50(th) Percentile Avoid the Threat of Older Adults Becoming Institutionalized: A Cross-sectional Pilot Study.

    PubMed

    Pereira, Catarina; Fernandes, Jorge; Raimundo, Armando; Biehl-Printes, Clarissa; Marmeleira, José; Tomas-Carus, Pablo

    2016-02-01

    The objective of this study was to analyze the impact of physical fitness and physical activity on the threat of older adults without cognitive impairment becoming institutionalized. This cross-sectional study involved 195 non-institutionalized (80.1 ± 4.4 years) and 186 institutionalized (83.8 ± 5.2years) participants. Cognitive impairment was assessed using Mini-Mental State Examination, measures of physical fitness were determined by the Senior Fitness Test, and physical activity was assessed using the International Physical Activity Questionnaire. Multivariate binary logistic analysis selected four main determinants of institutionalization in both genders: The likelihood of becoming institutionalized increased by +18.6% for each additional year of age, whereas it decreased by -24.8% by each fewer kg/m(2) in body mass index (BMI), by -0.9% for each additional meter performed in the aerobic endurance test, and by -2.0% for each additional 100 metabolic equivalent of task (MET)-min/week of physical activity expenditure (p < 0.05). Values ≤50(th) percentile (age ≥81 years, BMI ≥26.7 kg/m(2), aerobic endurance ≤367.6 meters, and physical activity ≤693 MET-min/week) were computed using receiver operating characteristics analysis as cutoffs discriminating institutionalized from non-institutionalized older adults. The performance of physical activity, allied to an improvement in physical fitness (mainly BMI and aerobic endurance), may avoid the threat of institutionalization of older adults without cognitive impairment only if they are above the 50(th) percentile. The following parameters are highly recommended: Expending ≥693 MET-min/week on physical activity, having a BMI ≤26.7 kg/m(2), and being able to walk ≥367.6 meters in the aerobic endurance test, especially above the age of 80 years. The discovery of this trigger justifies the development of physical activity programs targeting the pointed cutoffs in old and very old adults.

  4. The Human Brain Maintains Contradictory and Redundant Auditory Sensory Predictions

    PubMed Central

    Pieszek, Marika; Widmann, Andreas; Gruber, Thomas; Schröger, Erich

    2013-01-01

    Computational and experimental research has revealed that auditory sensory predictions are derived from regularities of the current environment by using internal generative models. However, so far, what has not been addressed is how the auditory system handles situations giving rise to redundant or even contradictory predictions derived from different sources of information. To this end, we measured error signals in the event-related brain potentials (ERPs) in response to violations of auditory predictions. Sounds could be predicted on the basis of overall probability, i.e., one sound was presented frequently and another sound rarely. Furthermore, each sound was predicted by an informative visual cue. Participants’ task was to use the cue and to discriminate the two sounds as fast as possible. Violations of the probability based prediction (i.e., a rare sound) as well as violations of the visual-auditory prediction (i.e., an incongruent sound) elicited error signals in the ERPs (Mismatch Negativity [MMN] and Incongruency Response [IR]). Particular error signals were observed even in case the overall probability and the visual symbol predicted different sounds. That is, the auditory system concurrently maintains and tests contradictory predictions. Moreover, if the same sound was predicted, we observed an additive error signal (scalp potential and primary current density) equaling the sum of the specific error signals. Thus, the auditory system maintains and tolerates functionally independently represented redundant and contradictory predictions. We argue that the auditory system exploits all currently active regularities in order to optimally prepare for future events. PMID:23308266

  5. Cryogenic Quad-Redundant Thermal Switch

    NASA Astrophysics Data System (ADS)

    Thompson, B. C.; Lloyd, B.; Schick, S. H.; Li, L.

    2008-03-01

    A Quad-Redundant Thermal Switch (QRTS) for the James Webb Space Telescope has been successfully designed, fabricated, and tested at the Space Dynamics Laboratory (SDL). A flight-like prototype successfully passed thermal and structural qualification tests in a representative space environment and achieved Technology Readiness Level 6. The QRTS serves as a high thermal conductance, high reliability thermal connect/disconnect between heat sources and sinks. The switch design is passively closed over the entire operational range of 32-300 K. The construction is an all metallic core packaged in a cross-strapped quad-redundant configuration. Actuation of the switch is based on differential thermal expansion and is opened by applying heat to the mechanism. Key qualification tests included: robust characterization of thermal closed and open performance from 32 to 313 K; and a full suite of vibration testing (sine, random, and sine burst). This paper presents an overview of the QRTS functionality, thermal and structural qualification tests, and resulting switch performance.

  6. Application of redundancy analysis for aerobiological data

    NASA Astrophysics Data System (ADS)

    Sadyś, Magdalena; Strzelczak, Agnieszka; Grinn-Gofroń, Agnieszka; Kennedy, Roy

    2015-01-01

    An aerobiological survey was conducted through five consecutive years (2006-2010) at Worcester (England). The concentration of 20 allergenic fungal spore types was measured using a 7-day volumetric spore trap. The relationship between investigated fungal spore genera and selected meteorological parameters (maximum, minimum, mean and dew point temperatures, rainfall, relative humidity, air pressure, wind direction) was examined using an ordination method (redundancy analysis) to determine which environmental factors favoured their most abundance in the air and whether it would be possible to detect similarities between different genera in their distribution pattern. Redundancy analysis provided additional information about the biology of the studied fungi through the results of the Spearman's rank correlation. Application of the variance inflation factor in canonical correspondence analysis indicated which explanatory variables were auto-correlated and needed to be excluded from further analyses. Obtained information will be consequently implemented in the selection of factors that will be a foundation for forecasting models for allergenic fungal spores in the future.

  7. Approach/avoidance in dreams.

    PubMed

    Malcolm-Smith, Susan; Koopowitz, Sheri; Pantelis, Eleni; Solms, Mark

    2012-03-01

    The influential threat simulation theory (TST) asserts that dreaming yields adaptive advantage by providing a virtual environment in which threat-avoidance may be safely rehearsed. We have previously found the incidence of biologically threatening dreams to be around 20%, with successful threat avoidance occurring in approximately one-fifth of such dreams. TST asserts that threat avoidance is over-represented relative to other possible dream contents. To begin assessing this issue, we contrasted the incidence of 'avoidance' dreams with that of their opposite: 'approach' dreams. Because TST states that the threat-avoidance function is only fully activated in ecologically valid (biologically threatening) contexts, we also performed this contrast for populations living in both high- and low-threat environments. We find that 'approach' dreams are significantly more prevalent across both contexts. We suggest these results are more consistent with the view that dreaming is generated by reward-seeking systems than by fear-conditioning systems, although reward-seeking is clearly not the only factor determining the content of dreams.

  8. Time-dependent impairment of inhibitory avoidance retention in rats by posttraining infusion of a mitogen-activated protein kinase kinase inhibitor into cortical and limbic structures.

    PubMed

    Walz, R; Roesler, R; Quevedo, J; Sant'Anna, M K; Madruga, M; Rodrigues, C; Gottfried, C; Medina, J H; Izquierdo, I

    2000-01-01

    Mitogen-activated protein kinase (MAPK) is abundantly expressed in postmitotic neurons of the developed nervous system. MAPK is activated and required for induction of long-term potentiation (LTP) in the CA1 area of the hippocampus, which is blocked by the specific inhibitor of the MAPK kinase, PD 098059. Recently it was demonstrated that MAPK is activated in the hippocampus after training and is necessary for contextual fear conditioning learning. The present work tests the role of the MAPK cascade in step-down inhibitory avoidance (IA) retention. PD 098059 (50 microM) was bilaterally injected (0.5 microl/side) into the CA1 region of the dorsal hippocampus or entorhinal cortex at 0, 90, 180, or 360 min, or into the amygdala or parietal cortex at 0, 180, or 360 min after IA training in rats using a 0.4-mA foot shock. Retention testing was carried out 24 h after training. PD 098059 impaired retention when injected into the dorsal hippocampus at 180 min, but not 0, 90, and 360 min after training. When infused into the entorhinal cortex, PD 098059 was amnestic at 0 and 180 min, but not at 90 and 360 min after training. The MAPKK inhibitor also impairs IA retention when infused into the parietal cortex immediately after training, but not at 180 or 360 min. Infusions performed into amygdala were amnestic at 180 min, but not at 0 and 360 min after training. Our results suggest a time-dependent involvement of the MAPK cascade in the posttraining memory processing of IA; the time dependency is different in the hippocampus, amygdala, entorhinal cortex, or parietal cortex of rats.

  9. Kinematic functions for redundancy resolution using configuration control

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun (Inventor)

    1994-01-01

    The invention fulfills new goals for redundancy resolution based on manipulator dynamics and end-effector characteristics. These goals are accomplished by employing the recently developed configuration control approach. Redundancy resolution is achieved by controlling the joint inertia matrix of the end-effector mass matrix that affect the inertial torques or by reducing the joint torques due to gravity loading and payload. The manipulator mechanical-advantage and velocity-ratio are also used as performance measures to be improved by proper utilization of redundancy. Furthermore, end-effector compliance, sensitivity, and impulsive force at impact are introduced as redundancy resolution criteria. The new goals for redundancy resolution allow a more efficient utilization of the redundant joints based on the desired task requirements.

  10. Method and apparatus for configuration control of redundant robots

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun (Inventor)

    1991-01-01

    A method and apparatus to control a robot or manipulator configuration over the entire motion based on augmentation of the manipulator forward kinematics is disclosed. A set of kinematic functions is defined in Cartesian or joint space to reflect the desirable configuration that will be achieved in addition to the specified end-effector motion. The user-defined kinematic functions and the end-effector Cartesian coordinates are combined to form a set of task-related configuration variables as generalized coordinates for the manipulator. A task-based adaptive scheme is then utilized to directly control the configuration variables so as to achieve tracking of some desired reference trajectories throughout the robot motion. This accomplishes the basic task of desired end-effector motion, while utilizing the redundancy to achieve any additional task through the desired time variation of the kinematic functions. The present invention can also be used for optimization of any kinematic objective function, or for satisfaction of a set of kinematic inequality constraints, as in an obstacle avoidance problem. In contrast to pseudoinverse-based methods, the configuration control scheme ensures cyclic motion of the manipulator, which is an essential requirement for repetitive operations. The control law is simple and computationally very fast, and does not require either the complex manipulator dynamic model or the complicated inverse kinematic transformation. The configuration control scheme can alternatively be implemented in joint space.

  11. Analytic redundancy management for systems with appreciable structural dynamics. [for control systems design

    NASA Technical Reports Server (NTRS)

    Montgomery, Raymond C.

    1988-01-01

    This paper deals with analytic redundancy management of systems that have appreciable structural dynamics and require active control. The class of systems considered is large, lightweight spacecraft that have large numbers of distributed sensors and actuators. Both preliminary design and on-line operations are studied. For the preliminary design we deal with the placement of the sensor and actuator components on a highly flexible spacecraft. For on-line operation an analytic redundancy management system based on examination of the residuals of a Kalman filter is considered. A large, flexible grid made of overlapping aluminum bars is used to experimentally evaluate this analytic redundancy management system. Results of the experimental evaluation are included in the paper.

  12. Entropy-Based Bounds On Redundancies Of Huffman Codes

    NASA Technical Reports Server (NTRS)

    Smyth, Padhraic J.

    1992-01-01

    Report presents extension of theory of redundancy of binary prefix code of Huffman type which includes derivation of variety of bounds expressed in terms of entropy of source and size of alphabet. Recent developments yielded bounds on redundancy of Huffman code in terms of probabilities of various components in source alphabet. In practice, redundancies of optimal prefix codes often closer to 0 than to 1.

  13. Avoiding Computer Viruses.

    ERIC Educational Resources Information Center

    Rowe, Joyce; And Others

    1989-01-01

    The threat of computer sabotage is a real concern to business teachers and others responsible for academic computer facilities. Teachers can minimize the possibility. Eight suggestions for avoiding computer viruses are given. (JOW)

  14. Avoiding Construction Snafus.

    ERIC Educational Resources Information Center

    Rochefort, Mark; Gosch, Jerry

    2001-01-01

    Discusses risk management planning tips that help schools avoid project-delaying construction problems. Preconstruction planning topics explored include the type of construction method to use, contract selection, and the need for efficient project management. (GR)

  15. Avoiding the SCAMs.

    PubMed

    Kidd, Thomas; Condron, Barry

    2007-05-01

    Dendrites from the same neuron usually avoid contact with one another, a behavior known as self-avoidance. In this issue of Neuron and in the upcoming May 4, 2007 issue of Cell, a pair of studies by Soba et al. and Hughes et al. and a study by Matthews et al., respectively, identify products from the highly alternatively spliced Dscam gene as central to this behavior in Drosophila. Signaling induced by adhesion between identical isoforms triggers repulsion between sister dendrites.

  16. Avoided Crossing and Synchronization

    NASA Astrophysics Data System (ADS)

    Sekii, T.; Shibahashi, H.

    2013-12-01

    We examine avoided crossing of stellar pulsations in the nonlinear regime, where synchronization may occur, based on a simple model of weakly coupled van der Pol oscillators with close frequencies. For this simple case, avoided crossing is unaffected in the sense that there is a frequency difference between the symmetric and antisymmetric modes, but as a result of synchronization, unlike the linear oscillations case, the system can vibrate in only one of the modes.

  17. Operational Collision Avoidance

    NASA Technical Reports Server (NTRS)

    Guit, Bill

    2015-01-01

    This presentation will describe the early days of the EOS Aqua and Aura operational collision avoidance process. It will highlight EOS debris avoidance maneuvers, EOS high interest event statistic and A-Train systematic conjunctions and conclude with future challenges. This is related to earlier e-DAA (tracking number 21692) that an abstract was submitted to a different conference. Eric Moyer, ESMO Deputy Project Manager has reviewed and approved this presentation on May 6, 2015

  18. Exploiting data redundancy in computational optical imaging.

    PubMed

    Munro, Peter R T

    2015-11-30

    We present an algorithm which exploits data redundancy to make computational, coherent, optical imaging more computationally efficient. This algorithm specifically addresses the computation of how light scattered by a sample is collected and coherently detected. It is of greatest benefit in the simulation of broadband optical systems employing coherent detection, such as optical coherence tomography. Although also amenable to time-harmonic data, the algorithm is designed to be embedded within time-domain electromagnetic scattering simulators such as the psuedo-spectral and finite-difference time domain methods. We derive the algorithm in detail as well as criteria which ensure accurate execution of the algorithm. We present simulations that verify the developed algorithm and demonstrate its utility. We expect this algorithm to be important to future developments in computational imaging.

  19. Serial data transmission between redundant channels

    NASA Technical Reports Server (NTRS)

    Tulpule, Bhalchandra R. (Inventor); Binnall, Daniel G. (Inventor)

    1992-01-01

    Data is communicated between redundant channels formatted in blocks having an initial command word followed by a destination code, starting address and a variable number of data words including a word count. The blocks are transmitted between each channel and all of the channels over cross-channel data links, each channel receiving the data blocks and determining the validity thereof by counting the number of data words received and comparing that number to the word count transmitted for that block. An interrupt signal indicative of invalidity of a block is provided in the event of a miscompare. A stop address is generated for each block received for storage at the start address. A memory address is generated for each valid word received for storage in sequence starting immediately after the start address. The next block received has its start address placed immediately at the end of the previously received block.

  20. Tomographical imaging using uniformly redundant arrays

    NASA Technical Reports Server (NTRS)

    Cannon, T. M.; Fenimore, E. E.

    1979-01-01

    An investigation is conducted of the behavior of two types of uniformly redundant array (URA) when used for close-up imaging. One URA pattern is a quadratic residue array whose characteristics for imaging planar sources have been simulated by Fenimore and Cannon (1978), while the second is based on m sequences that have been simulated by Gunson and Polychronopulos (1976) and by MacWilliams and Sloan (1976). Close-up imaging is necessary in order to obtain depth information for tomographical purposes. The properties of the two URA patterns are compared with a random array of equal open area. The goal considered in the investigation is to determine if a URA pattern exists which has the desirable defocus properties of the random array while maintaining artifact-free image properties for in-focus objects.

  1. Mortality, Redundancy, and Diversity in Stochastic Search

    NASA Astrophysics Data System (ADS)

    Meerson, Baruch; Redner, S.

    2015-05-01

    We investigate a stochastic search process in one dimension under the competing roles of mortality, redundancy, and diversity of the searchers. This picture represents a toy model for the fertilization of an oocyte by sperm. A population of N independent and mortal diffusing searchers all start at x =L and attempt to reach the target at x =0 . When mortality is irrelevant, the search time scales as τD/ln N for ln N ≫1 , where τD˜L2/D is the diffusive time scale. Conversely, when the mortality rate μ of the searchers is sufficiently large, the search time scales as √{τD/μ }, independent of N . When searchers have distinct and high mortalities, a subpopulation with a nontrivial optimal diffusivity is most likely to reach the target. We also discuss the effect of chemotaxis on the search time and its fluctuations.

  2. Design and development of the redundant launcher stabilization system for the Atlas 2 launch vehicle

    NASA Technical Reports Server (NTRS)

    Nakamura, M.

    1991-01-01

    The Launcher Stabilization System (LSS) is a pneumatic/hydraulic ground system used to support an Atlas launch vehicle prior to launch. The redesign and development activity undertaken to achieve an LSS with increased load capacity and a redundant hydraulic system for the Atlas 2 launch vehicle are described.

  3. Cold-standby redundancy allocation problem with degrading components

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Xiong, Junlin; Xie, Min

    2015-11-01

    Components in cold-standby state are usually assumed to be as good as new when they are activated. However, even in a standby environment, the components will suffer from performance degradation. This article presents a study of a redundancy allocation problem (RAP) for cold-standby systems with degrading components. The objective of the RAP is to determine an optimal design configuration of components to maximize system reliability subject to system resource constraints (e.g. cost, weight). As in most cases, it is not possible to obtain a closed-form expression for this problem, and hence, an approximated objective function is presented. A genetic algorithm with dual mutation is developed to solve such a constrained optimization problem. Finally, a numerical example is given to illustrate the proposed solution methodology.

  4. Reactive Collision Avoidance Algorithm

    NASA Technical Reports Server (NTRS)

    Scharf, Daniel; Acikmese, Behcet; Ploen, Scott; Hadaegh, Fred

    2010-01-01

    The reactive collision avoidance (RCA) algorithm allows a spacecraft to find a fuel-optimal trajectory for avoiding an arbitrary number of colliding spacecraft in real time while accounting for acceleration limits. In addition to spacecraft, the technology can be used for vehicles that can accelerate in any direction, such as helicopters and submersibles. In contrast to existing, passive algorithms that simultaneously design trajectories for a cluster of vehicles working to achieve a common goal, RCA is implemented onboard spacecraft only when an imminent collision is detected, and then plans a collision avoidance maneuver for only that host vehicle, thus preventing a collision in an off-nominal situation for which passive algorithms cannot. An example scenario for such a situation might be when a spacecraft in the cluster is approaching another one, but enters safe mode and begins to drift. Functionally, the RCA detects colliding spacecraft, plans an evasion trajectory by solving the Evasion Trajectory Problem (ETP), and then recovers after the collision is avoided. A direct optimization approach was used to develop the algorithm so it can run in real time. In this innovation, a parameterized class of avoidance trajectories is specified, and then the optimal trajectory is found by searching over the parameters. The class of trajectories is selected as bang-off-bang as motivated by optimal control theory. That is, an avoiding spacecraft first applies full acceleration in a constant direction, then coasts, and finally applies full acceleration to stop. The parameter optimization problem can be solved offline and stored as a look-up table of values. Using a look-up table allows the algorithm to run in real time. Given a colliding spacecraft, the properties of the collision geometry serve as indices of the look-up table that gives the optimal trajectory. For multiple colliding spacecraft, the set of trajectories that avoid all spacecraft is rapidly searched on

  5. ENU mutagenesis screening for dominant behavioral mutations based on normal control data obtained in home-cage activity, open-field, and passive avoidance tests.

    PubMed

    Wada, Yumiko; Furuse, Tamio; Yamada, Ikuko; Masuya, Hiroshi; Kushida, Tomoko; Shibukawa, Yoko; Nakai, Yuji; Kobayashi, Kimio; Kaneda, Hideki; Gondo, Yoichi; Noda, Tetsuo; Shiroishi, Toshihiko; Wakana, Shigeharu

    2010-01-01

    To establish the cutoff values for screening ENU-induced behavioral mutations, normal variations in mouse behavioral data were examined in home-cage activity (HA), open-field (OF), and passive-avoidance (PA) tests. We defined the normal range as one that included more than 95% of the normal control values. The cutoffs were defined to identify outliers yielding values that deviated from the normal by less than 5% for C57BL/6J, DBA/2J, DBF(1), and N(2) (DXDB) progenies. Cutoff values for G1-phenodeviant (DBF(1)) identification were defined based on values over +/- 3.0 SD from the mean of DBF(1) for all parameters assessed in the HA and OF tests. For the PA test, the cutoff values were defined based on whether the mice met the learning criterion during the 2nd (at a shock intensity of 0.3 mA) or the 3rd (at a shock intensity of 0.15 mA) retention test. For several parameters, the lower outliers were undetectable as the calculated cutoffs were negative values. Based on the cutoff criteria, we identified 275 behavioral phenodeviants among 2,646 G1 progeny. Of these, 64 were crossed with wild-type DBA/2J individuals, and the phenotype transmission was examined in the G2 progeny using the cutoffs defined for N(2) mice. In the G2 mice, we identified 15 novel dominant mutants exhibiting behavioral abnormalities, including hyperactivity in the HA or OF tests, hypoactivity in the OF test, and PA deficits. Genetic and detailed behavioral analysis of these ENU-induced mutants will provide novel insights into the molecular mechanisms underlying behavior.

  6. Collision Avoidance System

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Ames Research Center teamed with the Federal Aviation Administration (FAA) to study human performance factors associated with the use of the Traffic Alert and Collision Avoidance system (TCAS II) in an operational environment. TCAS is designed to alert pilots of the presence of other aircraft in their vicinity, to identify and track those who could be a threat, and to recommend action to avoid a collision. Ames conducted three laboratory experiments. The first showed that pilots were able to use the TCAS II correctly in the allowable time. The second tested pilots' response to changes in the avoidance advisories, and the third examined pilots' reactions to alternative displays. After a 1989 congressional mandate, the FAA ruled that TCAS would be required on all passenger carrying aircraft (to be phased in completely by 1995).

  7. Partial Verbal Redundancy in Multimedia Presentations for Writing Strategy Instruction

    ERIC Educational Resources Information Center

    Roscoe, Rod D.; Jacovina, Matthew E.; Harry, Danielle; Russell, Devin G.; McNamara, Danielle S.

    2015-01-01

    Multimedia instructional materials require learners to select, organize, and integrate information across multiple modalities. To facilitate these comprehension processes, a variety of multimedia design principles have been proposed. This study further explores the redundancy principle by manipulating the degree of partial redundancy between…

  8. 36 CFR 1193.35 - Redundancy and selectability. [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Redundancy and selectability. 1193.35 Section 1193.35 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS... § 1193.35 Redundancy and selectability....

  9. An Exploration of Concise Redundancy in Online Multimedia Learning

    ERIC Educational Resources Information Center

    Wu, Yu-Feng

    2011-01-01

    With the rapid growth of multimedia in education, the importance of investigating the effect of redundancy, repeating instructional messages to enhance conceptualization in instructional material design, is becoming more important. Various studies have been conducted recently regarding the effects of different forms of redundancy. A multimedia…

  10. 36 CFR 1193.35 - Redundancy and selectability. [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Redundancy and selectability. 1193.35 Section 1193.35 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS... § 1193.35 Redundancy and selectability....

  11. Using redundancy to repair video damaged by network data loss

    NASA Astrophysics Data System (ADS)

    Liu, Yanlin; Claypool, Mark

    1999-12-01

    With rapid progress in both computers and networks, real- time multimedia applications are now possible on the Internet. Sine the Internet was designed to support traditional applications, multimedia applications on the Internet often suffer from unacceptable delay, jitter and data loss. Among these, data loss often has the largest impact on quality. In this paper, we propose a new forward error correction technique for video that compensates for lost packets, while maintaining minimal delay. Our approach transmits a small, low-quality redundant frame after each full-quality primary frame. In the event the primary frame is lost, we display the low-quality frame, rather than display the previous frame or retransmit the primary frame. To evaluate our approach, we simulated the effect of network data loss on MPEG video clips and repaired the data loss by using redundancy frames. We conducted user studies that experimentally measured users' opinions on the quality of the video streams in the presence of data loss, both with and without our redundancy approach. In addition, we analyze the system overhead incurred by the redundancy. We find that video redundancy can greatly improve the perceptual quality of video in the presence of network data loss. The system overhead that redundancy introduces is dependent on the quality of the redundant frames, but a typical redundancy overhead will be approximately 10% that of the original frames.

  12. Reducing Redundancies in Reconfigurable Antenna Structures Using Graph Models

    SciTech Connect

    Costantine, Joseph; al-Saffar, Sinan; Christodoulou, Christos G.; Abdallah, Chaouki T.

    2010-04-23

    Many reconfigurable antennas have redundant components in their structures. In this paper we present an approach for reducing redundancies in reconfigurable antenna structures using graph models. We study reconfigurable antennas, which are grouped, categorized and modeled according to a set of proposed graph rules. Several examples are presented and discussed to demonstrate the validity of this new technique.

  13. A Model and Simple Iterative Algorithm for Redundancy Analysis.

    ERIC Educational Resources Information Center

    Fornell, Claes; And Others

    1988-01-01

    This paper shows that redundancy maximization with J. K. Johansson's extension can be accomplished via a simple iterative algorithm based on H. Wold's Partial Least Squares. The model and the iterative algorithm for the least squares approach to redundancy maximization are presented. (TJH)

  14. Intersensory redundancy promotes visual rhythm discrimination in visually impaired infants.

    PubMed

    Brenna, Viola; Nava, Elena; Turati, Chiara; Montirosso, Rosario; Cavallini, Anna; Borgatti, Renato

    2015-05-01

    Infants' attention is captured by the redundancy of amodal stimulation in multimodal objects and events. Evidence from this study demonstrates that intersensory redundancy can facilitate discrimination of rhythm changes presented in the visual modality alone in visually impaired infants, suggesting that multisensory rehabilitation strategies could prove helpful in this population.

  15. Exploring the Boundary Conditions of the Redundancy Principle

    ERIC Educational Resources Information Center

    McCrudden, Matthew T.; Hushman, Carolyn J.; Marley, Scott C.

    2014-01-01

    This experiment investigated whether study of a scientific text and a visual display that contained redundant text segments would affect memory and transfer. The authors randomly assigned 42 students from a university in the southwestern United States in equal numbers to 1 of 2 conditions: (a) a redundant condition, in which participants studied a…

  16. Hippocampal-dependent memory in the plus-maze discriminative avoidance task: The role of spatial cues and CA1 activity.

    PubMed

    Leão, Anderson H F F; Medeiros, André M; Apolinário, Gênedy K S; Cabral, Alícia; Ribeiro, Alessandra M; Barbosa, Flávio F; Silva, Regina H

    2016-05-01

    The plus-maze discriminative avoidance task (PMDAT) has been used to investigate interactions between aversive memory and an anxiety-like response in rodents. Suitable performance in this task depends on the activity of the basolateral amygdala, similar to other aversive-based memory tasks. However, the role of spatial cues and hippocampal-dependent learning in the performance of PMDAT remains unknown. Here, we investigated the role of proximal and distal cues in the retrieval of this task. Animals tested under misplaced proximal cues had diminished performance, and animals tested under both misplaced proximal cues and absent distal cues could not discriminate the aversive arm. We also assessed the role of the dorsal hippocampus (CA1) in this aversive memory task. Temporary bilateral inactivation of dorsal CA1 was conducted with muscimol (0.05 μg, 0.1 μg, and 0.2 μg) prior to the training session. While the acquisition of the task was not altered, muscimol impaired the performance in the test session and reduced the anxiety-like response in the training session. We also performed a spreading analysis of a fluorophore-conjugated muscimol to confirm selective inhibition of CA1. In conclusion, both distal and proximal cues are required to retrieve the task, with the latter being more relevant to spatial orientation. Dorsal CA1 activity is also required for aversive memory formation in this task, and interfered with the anxiety-like response as well. Importantly, both effects were detected by different parameters in the same paradigm, endorsing the previous findings of independent assessment of aversive memory and anxiety-like behavior in the PMDAT. Taken together, these findings suggest that the PMDAT probably requires an integration of multiple systems for memory formation, resembling an episodic-like memory rather than a pure conditioning behavior. Furthermore, the concomitant and independent assessment of emotionality and memory in rodents is relevant to

  17. An inverse kinematics algorithm for a highly redundant variable-geometry-truss manipulator

    NASA Technical Reports Server (NTRS)

    Naccarato, Frank; Hughes, Peter

    1989-01-01

    A new class of robotic arm consists of a periodic sequence of truss substructures, each of which has several variable-length members. Such variable-geometry-truss manipulator (VGTMs) are inherently highly redundant and promise a significant increase in dexterity over conventional anthropomorphic manipulators. This dexterity may be exploited for both obstacle avoidance and controlled deployment in complex workspaces. The inverse kinematics problem for such unorthodox manipulators, however, becomes complex because of the large number of degrees of freedom, and conventional solutions to the inverse kinematics problem become inefficient because of the high degree of redundancy. A solution is presented to this problem based on a spline-like reference curve for the manipulator's shape. Such an approach has a number of advantages: (1) direct, intuitive manipulation of shape; (2) reduced calculation time; and (3) direct control over the effective degree of redundancy of the manipulator. Furthermore, although the algorithm was developed primarily for variable-geometry-truss manipulators, it is general enough for application to a number of manipulator designs.

  18. Control algorithm implementation for a redundant degree of freedom manipulator

    NASA Technical Reports Server (NTRS)

    Cohan, Steve

    1991-01-01

    This project's purpose is to develop and implement control algorithms for a kinematically redundant robotic manipulator. The manipulator is being developed concurrently by Odetics Inc., under internal research and development funding. This SBIR contract supports algorithm conception, development, and simulation, as well as software implementation and integration with the manipulator hardware. The Odetics Dexterous Manipulator is a lightweight, high strength, modular manipulator being developed for space and commercial applications. It has seven fully active degrees of freedom, is electrically powered, and is fully operational in 1 G. The manipulator consists of five self-contained modules. These modules join via simple quick-disconnect couplings and self-mating connectors which allow rapid assembly/disassembly for reconfiguration, transport, or servicing. Each joint incorporates a unique drive train design which provides zero backlash operation, is insensitive to wear, and is single fault tolerant to motor or servo amplifier failure. The sensing system is also designed to be single fault tolerant. Although the initial prototype is not space qualified, the design is well-suited to meeting space qualification requirements. The control algorithm design approach is to develop a hierarchical system with well defined access and interfaces at each level. The high level endpoint/configuration control algorithm transforms manipulator endpoint position/orientation commands to joint angle commands, providing task space motion. At the same time, the kinematic redundancy is resolved by controlling the configuration (pose) of the manipulator, using several different optimizing criteria. The center level of the hierarchy servos the joints to their commanded trajectories using both linear feedback and model-based nonlinear control techniques. The lowest control level uses sensed joint torque to close torque servo loops, with the goal of improving the manipulator dynamic behavior

  19. Avoiding the "M" Word.

    ERIC Educational Resources Information Center

    Klinger, Donna

    2001-01-01

    Provides an overview of roundtable discussions by top business officers about how higher education can capitalize on strategic alliances. Describes how, by working with one another and with corporate partners, colleges and universities can avoid closing their doors or merging with stronger institutions. (EV)

  20. Psychological Treatments to Avoid

    ERIC Educational Resources Information Center

    Thomason, Timothy C.

    2010-01-01

    Certain psychological treatments should be avoided, and a list of such treatments would provide valuable guidance for counselors, as well as potential clients. It is well established that some therapies are potentially dangerous, and some fringe therapies are highly unlikely to help clients beyond a placebo effect. This article provides an…

  1. Myelin Avoids the JAM.

    PubMed

    Follis, Rose M; Carter, Bruce D

    2016-08-17

    In this issue of Neuron, Redmond et al. (2016) identify junction adhesion molecule 2 (JAM2) as an inhibitor of somatodendritic myelination in spinal cord neurons, thereby elucidating how myelin forms on axons but avoids dendrites and cell bodies. PMID:27537479

  2. Plants to Avoid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Knowledge of poisonous plants is extremely important for home owners, gardeners, farmers, hunters, hikers, and the rest of the general public. Among the most important plants to avoid in the Delta Region are poison ivy, bull nettle, eastern black nightshade, Queen Ann’s lace, jimsonweed, and trumpe...

  3. The Smooth Signal Redundancy Hypothesis: A Functional Explanation for Relationships between Redundancy, Prosodic Prominence, and Duration in Spontaneous Speech

    ERIC Educational Resources Information Center

    Aylett, Matthew; Turk, Alice

    2004-01-01

    This paper explores two related factors which influence variation in duration, prosodic structure and redundancy in spontaneous speech. We argue that the constraint of producing robust communication while efficiently expending articulatory effort leads to an inverse relationship between language redundancy and duration. The inverse relationship…

  4. Increasing Task Difficulty Enhances Effects of Intersensory Redundancy: Testing a New Prediction of the Intersensory Redundancy Hypothesis

    ERIC Educational Resources Information Center

    Bahrick, Lorraine E.; Lickliter, Robert; Castellanos, Irina; Vaillant-Molina, Mariana

    2010-01-01

    Prior research has demonstrated intersensory facilitation for perception of amodal properties of events such as tempo and rhythm in early development, supporting predictions of the Intersensory Redundancy Hypothesis (IRH). Specifically, infants discriminate amodal properties in bimodal, redundant stimulation but not in unimodal, nonredundant…

  5. The Effects of Race Conditions when Implementing Single-Source Redundant Clock Trees in Triple Modular Redundant Synchronous Architectures

    NASA Technical Reports Server (NTRS)

    Berg, Melanie D.; Label, Kenneth A.; Pellish, Jonathan

    2016-01-01

    We present the challenges that arise when using redundant clock domains due to their clock-skew. Heavy-ion radiation data show that a singular clock domain (DTMR) provides an improved TMR methodology for SRAM-based FPGAs over redundant clocks.

  6. Resistance, resilience, and redundancy in microbial communities

    PubMed Central

    Allison, Steven D.; Martiny, Jennifer B. H.

    2008-01-01

    Although it is generally accepted that plant community composition is key for predicting rates of ecosystem processes in the face of global change, microbial community composition is often ignored in ecosystem modeling. To address this issue, we review recent experiments and assess whether microbial community composition is resistant, resilient, or functionally redundant in response to four different disturbances. We find that the composition of most microbial groups is sensitive and not immediately resilient to disturbance, regardless of taxonomic breadth of the group or the type of disturbance. Other studies demonstrate that changes in composition are often associated with changes in ecosystem process rates. Thus, changes in microbial communities due to disturbance may directly affect ecosystem processes. Based on these relationships, we propose a simple framework to incorporate microbial community composition into ecosystem process models. We conclude that this effort would benefit from more empirical data on the links among microbial phylogeny, physiological traits, and disturbance responses. These relationships will determine how readily microbial community composition can be used to predict the responses of ecosystem processes to global change. PMID:18695234

  7. Restoring Redundancy to the MAP Propulsion System

    NASA Technical Reports Server (NTRS)

    ODonnell, James R., Jr.; Davis, Gary T.; Ward, David K.; Bauer, F. (Technical Monitor)

    2002-01-01

    The Microwave Anisotropy Probe is a follow-on to the Differential Microwave Radiometer instrument on the Cosmic Background Explorer. Sixteen months before launch, it was discovered that from the time of the critical design review, configuration changes had resulted in a significant migration of the spacecraft's center of mass. As a result, the spacecraft no longer had a viable backup control mode in the event of a failure of the negative pitch axis thruster. Potential solutions to this problem were identified, such as adding thruster plume shields to redirect thruster torque, adding mass to, or removing it from, the spacecraft, adding an additional thruster, moving thrusters, bending thrusters (either nozzles or propellant tubing), or accepting the loss of redundancy for the thruster. The impacts of each solution, including effects on the mass, cost, and fuel budgets, as well as schedule, were considered, and it was decided to bend the thruster propellant tubing of the two roll control thrusters, allowing that pair to be used for back-up control in the negative pitch axis. This paper discusses the problem and the potential solutions, and documents the hardware and software changes that needed to be made to implement the chosen solution. Flight data is presented to show the propulsion system on-orbit performance.

  8. Absence of “Warm-Up” during Active Avoidance Learning in a Rat Model of Anxiety Vulnerability: Insights from Computational Modeling

    PubMed Central

    Myers, Catherine E.; Smith, Ian M.; Servatius, Richard J.; Beck, Kevin D.

    2014-01-01

    Avoidance behaviors, in which a learned response causes omission of an upcoming punisher, are a core feature of many psychiatric disorders. While reinforcement learning (RL) models have been widely used to study the development of appetitive behaviors, less attention has been paid to avoidance. Here, we present a RL model of lever-press avoidance learning in Sprague-Dawley (SD) rats and in the inbred Wistar Kyoto (WKY) rat, which has been proposed as a model of anxiety vulnerability. We focus on “warm-up,” transiently decreased avoidance responding at the start of a testing session, which is shown by SD but not WKY rats. We first show that a RL model can correctly simulate key aspects of acquisition, extinction, and warm-up in SD rats; we then show that WKY behavior can be simulated by altering three model parameters, which respectively govern the tendency to explore new behaviors vs. exploit previously reinforced ones, the tendency to repeat previous behaviors regardless of reinforcement, and the learning rate for predicting future outcomes. This suggests that several, dissociable mechanisms may contribute independently to strain differences in behavior. The model predicts that, if the “standard” inter-session interval is shortened from 48 to 24 h, SD rats (but not WKY) will continue to show warm-up; we confirm this prediction in an empirical study with SD and WKY rats. The model further predicts that SD rats will continue to show warm-up with inter-session intervals as short as a few minutes, while WKY rats will not show warm-up, even with inter-session intervals as long as a month. Together, the modeling and empirical data indicate that strain differences in warm-up are qualitative rather than just the result of differential sensitivity to task variables. Understanding the mechanisms that govern expression of warm-up behavior in avoidance may lead to better understanding of pathological avoidance, and potential pathways to modify these processes. PMID

  9. Collision avoidance for CTV: Requirements and capabilities

    NASA Technical Reports Server (NTRS)

    Nosek, Thomas P.

    1991-01-01

    Cargo transfer vehicle (CTV) operations near Space Station Freedom will require positive collision avoidance maneuver (CAM) capability to preclude any change of collision, even in the event of CTV failures. The requirements for CAM are discussed, and the CAM design approach and design of the Orbiting Maneuvering Vehicle (OMV) are reviewed; this design met requirements for OMV operation near the Space Station, provided a redundant collision avoidance maneuver capability. Significant portions of the OMV CAM design should be applicable to CTV. The key features of the OMV design are summarized and related to the CTV mission design to that of OMV's. CAM is a defined sequence of events executed by the CTV to place the vehicle in a safe position relative to a target such as the Space Station. CAM can be performed through software commands to the propulsion system, or through commands pre-stored in hardware. Various techniques for triggering CAM are considered, and the risks associated with CAM enable and execution in phases are considered. OMV CAM design features both hardware and software CAM capability, with analyses conducted to assess the ability to meet the collision-free requirement during all phases of the mission.

  10. Collision avoidance for CTV: Requirements and capabilities

    NASA Astrophysics Data System (ADS)

    Nosek, Thomas P.

    Cargo transfer vehicle (CTV) operations near Space Station Freedom will require positive collision avoidance maneuver (CAM) capability to preclude any change of collision, even in the event of CTV failures. The requirements for CAM are discussed, and the CAM design approach and design of the Orbiting Maneuvering Vehicle (OMV) are reviewed; this design met requirements for OMV operation near the Space Station, provided a redundant collision avoidance maneuver capability. Significant portions of the OMV CAM design should be applicable to CTV. The key features of the OMV design are summarized and related to the CTV mission design to that of OMV's. CAM is a defined sequence of events executed by the CTV to place the vehicle in a safe position relative to a target such as the Space Station. CAM can be performed through software commands to the propulsion system, or through commands pre-stored in hardware. Various techniques for triggering CAM are considered, and the risks associated with CAM enable and execution in phases are considered. OMV CAM design features both hardware and software CAM capability, with analyses conducted to assess the ability to meet the collision-free requirement during all phases of the mission.

  11. YUCCA auxin biosynthetic genes are required for Arabidopsis shade avoidance

    PubMed Central

    Müller-Moulé, Patricia; Nozue, Kazunari; Pytlak, Melissa L.; Palmer, Christine M.; Covington, Michael F.; Wallace, Andreah D.; Harmer, Stacey L.

    2016-01-01

    Plants respond to neighbor shade by increasing stem and petiole elongation. Shade, sensed by phytochrome photoreceptors, causes stabilization of PHYTOCHROME INTERACTING FACTOR proteins and subsequent induction of YUCCA auxin biosynthetic genes. To investigate the role of YUCCA genes in phytochrome-mediated elongation, we examined auxin signaling kinetics after an end-of-day far-red (EOD-FR) light treatment, and found that an auxin responsive reporter is rapidly induced within 2 hours of far-red exposure. YUCCA2, 5, 8, and 9 are all induced with similar kinetics suggesting that they could act redundantly to control shade-mediated elongation. To test this hypothesis we constructed a yucca2, 5, 8, 9 quadruple mutant and found that the hypocotyl and petiole EOD-FR and shade avoidance responses are completely disrupted. This work shows that YUCCA auxin biosynthetic genes are essential for detectable shade avoidance and that YUCCA genes are important for petiole shade avoidance. PMID:27761349

  12. Avoiding congestion in recommender systems

    NASA Astrophysics Data System (ADS)

    Ren, Xiaolong; Lü, Linyuan; Liu, Runran; Zhang, Jianlin

    2014-06-01

    Recommender systems use the historical activities and personal profiles of users to uncover their preferences and recommend objects. Most of the previous methods are based on objects’ (and/or users’) similarity rather than on their difference. Such approaches are subject to a high risk of increasingly exposing users to a narrowing band of popular objects. As a result, a few objects may be recommended to an enormous number of users, resulting in the problem of recommendation congestion, which is to be avoided, especially when the recommended objects are limited resources. In order to quantitatively measure a recommendation algorithm's ability to avoid congestion, we proposed a new metric inspired by the Gini index, which is used to measure the inequality of the individual wealth distribution in an economy. Besides this, a new recommendation method called directed weighted conduction (DWC) was developed by considering the heat conduction process on a user-object bipartite network with different thermal conductivities. Experimental results obtained for three benchmark data sets showed that the DWC algorithm can effectively avoid system congestion, and greatly improve the novelty and diversity, while retaining relatively high accuracy, in comparison with the state-of-the-art methods.

  13. Advanced driver assistance systems: Using multimodal redundant warnings to enhance road safety.

    PubMed

    Biondi, Francesco; Strayer, David L; Rossi, Riccardo; Gastaldi, Massimiliano; Mulatti, Claudio

    2017-01-01

    This study investigated whether multimodal redundant warnings presented by advanced assistance systems reduce brake response times. Warnings presented by assistance systems are designed to assist drivers by informing them that evasive driving maneuvers are needed in order to avoid a potential accident. If these warnings are poorly designed, they may distract drivers, slow their responses, and reduce road safety. In two experiments, participants drove a simulated vehicle equipped with a forward collision avoidance system. Auditory, vibrotactile, and multimodal warnings were presented when the time to collision was shorter than five seconds. The effects of these warnings were investigated with participants performing a concurrent cell phone conversation (Exp. 1) or driving in high-density traffic (Exp. 2). Braking times and subjective workload were measured. Multimodal redundant warnings elicited faster braking reaction times. These warnings were found to be effective even when talking on a cell phone (Exp. 1) or driving in dense traffic (Exp. 2). Multimodal warnings produced higher ratings of urgency, but ratings of frustration did not increase compared to other warnings. Findings obtained in these two experiments are important given that faster braking responses may reduce the potential for a collision.

  14. Advanced driver assistance systems: Using multimodal redundant warnings to enhance road safety.

    PubMed

    Biondi, Francesco; Strayer, David L; Rossi, Riccardo; Gastaldi, Massimiliano; Mulatti, Claudio

    2017-01-01

    This study investigated whether multimodal redundant warnings presented by advanced assistance systems reduce brake response times. Warnings presented by assistance systems are designed to assist drivers by informing them that evasive driving maneuvers are needed in order to avoid a potential accident. If these warnings are poorly designed, they may distract drivers, slow their responses, and reduce road safety. In two experiments, participants drove a simulated vehicle equipped with a forward collision avoidance system. Auditory, vibrotactile, and multimodal warnings were presented when the time to collision was shorter than five seconds. The effects of these warnings were investigated with participants performing a concurrent cell phone conversation (Exp. 1) or driving in high-density traffic (Exp. 2). Braking times and subjective workload were measured. Multimodal redundant warnings elicited faster braking reaction times. These warnings were found to be effective even when talking on a cell phone (Exp. 1) or driving in dense traffic (Exp. 2). Multimodal warnings produced higher ratings of urgency, but ratings of frustration did not increase compared to other warnings. Findings obtained in these two experiments are important given that faster braking responses may reduce the potential for a collision. PMID:27633218

  15. How Redundant Are Redundant Color Adjectives? An Efficiency-Based Analysis of Color Overspecification

    PubMed Central

    Rubio-Fernández, Paula

    2016-01-01

    Color adjectives tend to be used redundantly in referential communication. I propose that redundant color adjectives (RCAs) are often intended to exploit a color contrast in the visual context and hence facilitate object identification, despite not being necessary to establish unique reference. Two language-production experiments investigated two types of factors that may affect the use of RCAs: factors related to the efficiency of color in the visual context and factors related to the semantic category of the noun. The results of Experiment 1 confirmed that people produce RCAs when color may facilitate object recognition; e.g., they do so more often in polychrome displays than in monochrome displays, and more often in English (pre-nominal position) than in Spanish (post-nominal position). RCAs are also used when color is a central property of the object category; e.g., people referred to the color of clothes more often than to the color of geometrical figures (Experiment 1), and they overspecified atypical colors more often than variable and stereotypical colors (Experiment 2). These results are relevant for pragmatic models of referential communication based on Gricean pragmatics and informativeness. An alternative analysis is proposed, which focuses on the efficiency and pertinence of color in a given referential situation. PMID:26924999

  16. How Redundant Are Redundant Color Adjectives? An Efficiency-Based Analysis of Color Overspecification.

    PubMed

    Rubio-Fernández, Paula

    2016-01-01

    Color adjectives tend to be used redundantly in referential communication. I propose that redundant color adjectives (RCAs) are often intended to exploit a color contrast in the visual context and hence facilitate object identification, despite not being necessary to establish unique reference. Two language-production experiments investigated two types of factors that may affect the use of RCAs: factors related to the efficiency of color in the visual context and factors related to the semantic category of the noun. The results of Experiment 1 confirmed that people produce RCAs when color may facilitate object recognition; e.g., they do so more often in polychrome displays than in monochrome displays, and more often in English (pre-nominal position) than in Spanish (post-nominal position). RCAs are also used when color is a central property of the object category; e.g., people referred to the color of clothes more often than to the color of geometrical figures (Experiment 1), and they overspecified atypical colors more often than variable and stereotypical colors (Experiment 2). These results are relevant for pragmatic models of referential communication based on Gricean pragmatics and informativeness. An alternative analysis is proposed, which focuses on the efficiency and pertinence of color in a given referential situation.

  17. Sibling rivalry: related bacterial small RNAs and their redundant and non-redundant roles

    PubMed Central

    Caswell, Clayton C.; Oglesby-Sherrouse, Amanda G.; Murphy, Erin R.

    2014-01-01

    Small RNA molecules (sRNAs) are now recognized as key regulators controlling bacterial gene expression, as sRNAs provide a quick and efficient means of positively or negatively altering the expression of specific genes. To date, numerous sRNAs have been identified and characterized in a myriad of bacterial species, but more recently, a theme in bacterial sRNAs has emerged: the presence of more than one highly related sRNAs produced by a given bacterium, here termed sibling sRNAs. Sibling sRNAs are those that are highly similar at the nucleotide level, and while it might be expected that sibling sRNAs exert identical regulatory functions on the expression of target genes based on their high degree of relatedness, emerging evidence is demonstrating that this is not always the case. Indeed, there are several examples of bacterial sibling sRNAs with non-redundant regulatory functions, but there are also instances of apparent regulatory redundancy between sibling sRNAs. This review provides a comprehensive overview of the current knowledge of bacterial sibling sRNAs, and also discusses important questions about the significance and evolutionary implications of this emerging class of regulators. PMID:25389522

  18. Effects of central activation of serotonin 5-HT2A/2C or dopamine D2/3 receptors on the acute and repeated effects of clozapine in the conditioned avoidance response test

    PubMed Central

    Feng, Min; Gao, Jun; Sui, Nan; Li, Ming

    2014-01-01

    Rationale: Acute administration of clozapine (a gold standard of atypical antipsychotics) disrupts avoidance response in rodents, while repeated administration often causes a tolerance effect. Objective: The present study investigated the neuroanatomical basis and receptor mechanisms of acute and repeated effects of clozapine treatment in the conditioned avoidance response test in male Sprague-Dawley rats. Methods: DOI (2,5-dimethoxy-4-iodo-amphetamine, a preferential 5-HT2A/2C agonist) or quinpirole (a preferential dopamine D2/3 agonist) was microinjected into the medial prefrontal cortex (mPFC) or nucleus accumbens shell (NAs), and their effects on the acute and long-term avoidance-disruptive effect of clozapine were tested. Results: Intra-mPFC microinjection of quinpirole enhanced the acute avoidance disruptive effect of clozapine (10 mg/kg, sc), while DOI microinjections reduced it marginally. Repeated administration of clozapine (10 mg/kg, sc) daily for 5 days caused a progressive decrease in its inhibition of avoidance responding, indicating tolerance development. Intra-mPFC microinjection of DOI at 25.0 (but not 5.0) μg/side during this period completely abolished the expression of clozapine tolerance. This was indicated by the finding that clozapine-treated rats centrally infused with 25.0 μg/side DOI did not show higher levels of avoidance responses than the vehicle-treated rats in the clozapine challenge test. Microinjection of DOI into the mPFC immediately before the challenge test also decreased the expression of clozapine tolerance. Conclusions: Acute behavioral effect of clozapine can be enhanced by activation of the D2/3 receptors in the mPFC. Clozapine tolerance expression relies on the neuroplasticity initiated by its antagonist action against 5-HT2A/2C receptors in the mPFC. PMID:25288514

  19. Backlash control via redundant drives: An experimental verification

    SciTech Connect

    Tsai, L.W.; Chang, S.L.

    1992-01-01

    In this paper, a novel concept for the control of backlash in geared servo-mechanisms is demonstrated with a prototype manipulator. The concept utilizes unidirectional redundant drives to assure positive coupling of gear meshes at all times and, thereby, eliminates backlash completely. To establish a proof of concept, a two-DOF prototype manipulator with three unidirectional drives is designed and tested. Dynamic model based on Language's formulation is established. A PID controller using computed torque control technique is developed. Two experiments, one with redundant drives and the other without redundant drives, are conducted. The experimental results demonstrate that use of unidirectional redundant drives improves the repeatability of a manipulator by an order of magnitude.

  20. Backlash control via redundant drives: An experimental verification

    SciTech Connect

    Tsai, L.W.; Chang, S.L.

    1992-08-01

    In this paper, a novel concept for the control of backlash in geared servo-mechanisms is demonstrated with a prototype manipulator. The concept utilizes unidirectional redundant drives to assure positive coupling of gear meshes at all times and, thereby, eliminates backlash completely. To establish a proof of concept, a two-DOF prototype manipulator with three unidirectional drives is designed and tested. Dynamic model based on Language`s formulation is established. A PID controller using computed torque control technique is developed. Two experiments, one with redundant drives and the other without redundant drives, are conducted. The experimental results demonstrate that use of unidirectional redundant drives improves the repeatability of a manipulator by an order of magnitude.

  1. Generation of Luby Transform Codes with Low Redundancy

    NASA Astrophysics Data System (ADS)

    Zhao, Yuli; Lau, Francis C. M.; Zhu, Zhiliang; Zhang, Wei

    Given the same number of encoded symbols, a Luby Transform (LT) decoder is more likely to decode successfully when there is little redundancy among the symbols. With the use of a Tanner graph, we describe two kinds of redundancy appearing in LT codes in this paper. We further propose an encoding algorithm called Low Redundancy (LR) algorithm used in the formation of the encoded symbols. The algorithm aims to reduce the redundancy of LT codes and to improve the decoder performance under the same complexity. Simulation results show various LT codes improve in terms of average overhead factor and probability of successful decoding when the codes are encoded using the proposed LR algorithm. Moreover, the encoding complexity remains unchanged.

  2. Muscle redundancy does not imply robustness to muscle dysfunction

    PubMed Central

    Kutch, Jason J.; Valero-Cuevas, Francisco J.

    2011-01-01

    It is well-known that muscle redundancy grants the CNS numerous options to perform a task. Does muscle redundancy, however, allow sufficient robustness to compensate for loss or dysfunction of even a single muscle? Are all muscles equally redundant? We combined experimental and computational approaches to establish the limits of motor robustness for static force production. In computer- controlled cadaveric index fingers, we find that only a small subset (<5%) of feasible forces is robust to loss of any one muscle. Importantly, the loss of certain muscles compromises force production significantly more than others. Further computational modeling of a multi-joint, multi-muscle leg demonstrates that this severe lack of robustness generalizes to whole limbs. These results provide a biomechanical basis to begin to explain why redundant motor systems can be vulnerable to even mild neuromuscular pathology. PMID:21420091

  3. Landing Hazard Avoidance Display

    NASA Technical Reports Server (NTRS)

    Abernathy, Michael Franklin (Inventor); Hirsh, Robert L. (Inventor)

    2016-01-01

    Landing hazard avoidance displays can provide rapidly understood visual indications of where it is safe to land a vehicle and where it is unsafe to land a vehicle. Color coded maps can indicate zones in two dimensions relative to the vehicles position where it is safe to land. The map can be simply green (safe) and red (unsafe) areas with an indication of scale or can be a color coding of another map such as a surface map. The color coding can be determined in real time based on topological measurements and safety criteria to thereby adapt to dynamic, unknown, or partially known environments.

  4. Redundancy-Aware Topic Modeling for Patient Record Notes

    PubMed Central

    Cohen, Raphael; Aviram, Iddo; Elhadad, Michael; Elhadad, Noémie

    2014-01-01

    The clinical notes in a given patient record contain much redundancy, in large part due to clinicians’ documentation habit of copying from previous notes in the record and pasting into a new note. Previous work has shown that this redundancy has a negative impact on the quality of text mining and topic modeling in particular. In this paper we describe a novel variant of Latent Dirichlet Allocation (LDA) topic modeling, Red-LDA, which takes into account the inherent redundancy of patient records when modeling content of clinical notes. To assess the value of Red-LDA, we experiment with three baselines and our novel redundancy-aware topic modeling method: given a large collection of patient records, (i) apply vanilla LDA to all documents in all input records; (ii) identify and remove all redundancy by chosing a single representative document for each record as input to LDA; (iii) identify and remove all redundant paragraphs in each record, leaving partial, non-redundant documents as input to LDA; and (iv) apply Red-LDA to all documents in all input records. Both quantitative evaluation carried out through log-likelihood on held-out data and topic coherence of produced topics and qualitative assessement of topics carried out by physicians show that Red-LDA produces superior models to all three baseline strategies. This research contributes to the emerging field of understanding the characteristics of the electronic health record and how to account for them in the framework of data mining. The code for the two redundancy-elimination baselines and Red-LDA is made publicly available to the community. PMID:24551060

  5. On the danger of redundancies in some aerospace mechanisms

    NASA Technical Reports Server (NTRS)

    Chew, M.

    1988-01-01

    An attempt is made to show that redundancies in some aerospace mechanisms do not generally improve the odds for success. Some of these redundancies may even be the very cause for failure of the system. To illustrate this fallacy, two designs based on the Control of Flexible Structures I (COFS I) Mast deployer and retractor assembly (DRA) are presented together with novel designs to circumvent such design inadequacies, while improving system reliability.

  6. Redundancy-aware topic modeling for patient record notes.

    PubMed

    Cohen, Raphael; Aviram, Iddo; Elhadad, Michael; Elhadad, Noémie

    2014-01-01

    The clinical notes in a given patient record contain much redundancy, in large part due to clinicians' documentation habit of copying from previous notes in the record and pasting into a new note. Previous work has shown that this redundancy has a negative impact on the quality of text mining and topic modeling in particular. In this paper we describe a novel variant of Latent Dirichlet Allocation (LDA) topic modeling, Red-LDA, which takes into account the inherent redundancy of patient records when modeling content of clinical notes. To assess the value of Red-LDA, we experiment with three baselines and our novel redundancy-aware topic modeling method: given a large collection of patient records, (i) apply vanilla LDA to all documents in all input records; (ii) identify and remove all redundancy by chosing a single representative document for each record as input to LDA; (iii) identify and remove all redundant paragraphs in each record, leaving partial, non-redundant documents as input to LDA; and (iv) apply Red-LDA to all documents in all input records. Both quantitative evaluation carried out through log-likelihood on held-out data and topic coherence of produced topics and qualitative assessment of topics carried out by physicians show that Red-LDA produces superior models to all three baseline strategies. This research contributes to the emerging field of understanding the characteristics of the electronic health record and how to account for them in the framework of data mining. The code for the two redundancy-elimination baselines and Red-LDA is made publicly available to the community. PMID:24551060

  7. Redundancy of classical and quantum correlations during decoherence

    SciTech Connect

    Paz, Juan Pablo; Roncaglia, Augusto J.

    2009-10-15

    We analyze the time dependence of entanglement and total correlations between a system and fractions of its environment in the course of decoherence. For the quantum Brownian motion model, we show that the entanglement and total correlations have rather different dependence on the size of the environmental fraction. Redundancy manifests differently in both types of correlations and can be related with induced classicality. To study this, we present a measure of redundancy and compare it to the existing one.

  8. Key herbivores reveal limited functional redundancy on inshore coral reefs

    NASA Astrophysics Data System (ADS)

    Johansson, C. L.; van de Leemput, I. A.; Depczynski, M.; Hoey, A. S.; Bellwood, D. R.

    2013-12-01

    Marine ecosystems are facing increasing exposure to a range of stressors and declines in critical ecological functions. The likelihood of further loss of functions and resilience is dependent, in part, on the extent of functional redundancy (i.e. the capacity of one species to functionally compensate for the loss of another species) within critical functional groups. We used multiple metrics; species richness, generic richness, abundance and reserve capacity (i.e. the relative number of individuals available to fulfil the function if the numerically dominant species is lost), as indicators to assess the potential functional redundancy of four functional groups of herbivorous fishes (browsers, excavators, grazers and scrapers) in two of the worlds' most intact coral reef ecosystems: the Great Barrier Reef (GBR) and Ningaloo Reef in Western Australia. We found marked variations in potential redundancy among habitats within each reef system and functional groups. Despite negligible fishing of herbivorous fishes, coastal habitats in both reef systems had lower functional redundancy compared to offshore locations for all herbivorous fishes collectively and the four functional groups independently. This pattern was consistent in all four indicators of redundancy. The potential vulnerability of these coastal habitats is highlighted by recent shifts from coral to macroalgal dominance on several coastal reefs of the GBR. Our approach provides a simple yet revealing evaluation of potential functional redundancy. Moreover, it highlights the spatial variation in potential vulnerability and resilience of reef systems.

  9. Diverse Redundant Systems for Reliable Space Life Support

    NASA Technical Reports Server (NTRS)

    Jones, Harry W.

    2015-01-01

    Reliable life support systems are required for deep space missions. The probability of a fatal life support failure should be less than one in a thousand in a multi-year mission. It is far too expensive to develop a single system with such high reliability. Using three redundant units would require only that each have a failure probability of one in ten over the mission. Since the system development cost is inverse to the failure probability, this would cut cost by a factor of one hundred. Using replaceable subsystems instead of full systems would further cut cost. Using full sets of replaceable components improves reliability more than using complete systems as spares, since a set of components could repair many different failures instead of just one. Replaceable components would require more tools, space, and planning than full systems or replaceable subsystems. However, identical system redundancy cannot be relied on in practice. Common cause failures can disable all the identical redundant systems. Typical levels of common cause failures will defeat redundancy greater than two. Diverse redundant systems are required for reliable space life support. Three, four, or five diverse redundant systems could be needed for sufficient reliability. One system with lower level repair could be substituted for two diverse systems to save cost.

  10. Obstacle-avoiding navigation system

    DOEpatents

    Borenstein, Johann; Koren, Yoram; Levine, Simon P.

    1991-01-01

    A system for guiding an autonomous or semi-autonomous vehicle through a field of operation having obstacles thereon to be avoided employs a memory for containing data which defines an array of grid cells which correspond to respective subfields in the field of operation of the vehicle. Each grid cell in the memory contains a value which is indicative of the likelihood, or probability, that an obstacle is present in the respectively associated subfield. The values in the grid cells are incremented individually in response to each scan of the subfields, and precomputation and use of a look-up table avoids complex trigonometric functions. A further array of grid cells is fixed with respect to the vehicle form a conceptual active window which overlies the incremented grid cells. Thus, when the cells in the active window overly grid cell having values which are indicative of the presence of obstacles, the value therein is used as a multiplier of the precomputed vectorial values. The resulting plurality of vectorial values are summed vectorially in one embodiment of the invention to produce a virtual composite repulsive vector which is then summed vectorially with a target-directed vector for producing a resultant vector for guiding the vehicle. In an alternative embodiment, a plurality of vectors surrounding the vehicle are computed, each having a value corresponding to obstacle density. In such an embodiment, target location information is used to select between alternative directions of travel having low associated obstacle densities.

  11. Highly specific role of hypocretin (orexin) neurons: differential activation as a function of diurnal phase, operant reinforcement versus operant avoidance and light level.

    PubMed

    McGregor, Ronald; Wu, Ming-Fung; Barber, Grace; Ramanathan, Lalini; Siegel, Jerome M

    2011-10-26

    Hypocretin (Hcrt) cell loss is responsible for narcolepsy, but Hcrt's role in normal behavior is unclear. We found that Hcrt knock-out mice were unable to work for food or water reward during the light phase. However, they were unimpaired relative to wild-type (WT) mice when working for reward during the dark phase or when working to avoid shock in the light or dark phase. In WT mice, expression of Fos in Hcrt neurons occurs only in the light phase when working for positive reinforcement. Expression was seen throughout the mediolateral extent of the Hcrt field. Fos was not expressed when expected or unexpected unearned rewards were presented, when working to avoid negative reinforcement, or when given or expecting shock, even though these conditions elicit maximal electroencephalogram (EEG) arousal. Fos was not expressed in the light phase when light was removed. This may explain the lack of light-induced arousal in narcoleptics and its presence in normal individuals. This is the first demonstration of such specificity of arousal system function and has implications for understanding the motivational and circadian consequences of arousal system dysfunction. The current results also indicate that comparable and complementary specificities must exist in other arousal systems.

  12. Avoiding dangerous climate change

    SciTech Connect

    Hans Joachim Schellnhuber; Wolfgang Cramer; Nebojsa Nakicenovic; Tom Wigley; Gary Yohe

    2006-02-15

    In 2005 the UK Government hosted the Avoiding Dangerous Climate Change conference to take an in-depth look at the scientific issues associated with climate change. This volume presents the most recent findings from the leading international scientists that attended the conference. The topics addressed include critical thresholds and key vulnerabilities of the climate system, impacts on human and natural systems, socioeconomic costs and benefits of emissions pathways, and technological options for meeting different stabilisation levels of greenhouse gases in the atmosphere. Contents are: Foreword from Prime Minister Tony Blair; Introduction from Rajendra Pachauri, Chairman of the IPCC; followed by 41 papers arranged in seven sections entitled: Key Vulnerabilities of the Climate System and Critical Thresholds; General Perspectives on Dangerous Impacts; Key Vulnerabilities for Ecosystems and Biodiversity; Socio-Economic Effects; Regional Perspectives; Emission Pathways; and Technological Options. Four papers have been abstracted separately for the Coal Abstracts database.

  13. 78 FR 76057 - Removal of Redundant Regulations

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-16

    ... captured in statues that govern NASA activities related to delegation of authority of certain civil rights functions, protection of human subjects, and care and use of animals in the conduct of NASA activities... activities related to delegation of authority of certain civil rights functions, protection of human...

  14. Measuring Experiential Avoidance in Adults: The Avoidance and Fusion Questionnaire

    ERIC Educational Resources Information Center

    Schmalz, Jonathan E.; Murrell, Amy R.

    2010-01-01

    To date, general levels of experiential avoidance are primarily measured by the Acceptance and Action Questionnaire-II (AAQ-II), but it includes items of questionable comprehensibility. The Avoidance and Fusion Questionnaire for Youth (AFQ-Y), previously validated as a measure of experiential avoidance with children and adolescents, was…

  15. Transcription coactivator PRIP, the peroxisome proliferator-activated receptor (PPAR)-interacting protein, is redundant for the function of nuclear receptors PParalpha and CAR, the constitutive androstane receptor, in mouse liver.

    PubMed

    Sarkar, Joy; Qi, Chao; Guo, Dongsheng; Ahmed, Mohamed R; Jia, Yuzhi; Usuda, Nobuteru; Viswakarma, Navin; Rao, M Sambasiva; Reddy, Janardan K

    2007-01-01

    Disruption of the genes encoding for the transcription coactivators, peroxisome proliferator-activated receptor (PPAR)-interacting protein (PRIP/ASC-2/RAP250/TRBP/NRC) and PPAR-binding protein (PBP/TRAP220/DRIP205/MED1), results in embryonic lethality by affecting placental and multiorgan development. Targeted deletion of coactivator PBP gene in liver parenchymal cells (PBP(LIV-/-)) results in the near abrogation of the induction of PPARalpha and CAR (constitutive androstane receptor)-regulated genes in liver. Here, we show that targeted deletion of coactivator PRIP gene in liver (PRIP(LIV-/-)) does not affect the induction of PPARalpha-regulated pleiotropic responses, including hepatomegaly, hepatic peroxisome proliferation, and induction of mRNAs of genes involved in fatty acid oxidation system, indicating that PRIP is not essential for PPARalpha-mediated transcriptional activity. We also provide additional data to show that liver-specific deletion of PRIP gene does not interfere with the induction of genes regulated by nuclear receptor CAR. Furthermore, disruption of PRIP gene in liver did not alter zoxazolamine-induced paralysis, and acetaminophen-induced hepatotoxicity. Studies with adenovirally driven EGFP-CAR expression in liver demonstrated that, unlike PBP, the absence of PRIP does not prevent phenobarbital-mediated nuclear translocation/retention of the receptor CAR in liver in vivo and cultured hepatocytes in vitro. These results show that PRIP deficiency in liver does not interfere with the function of nuclear receptors PPARalpha and CAR. The dependence of PPARalpha- and CAR-regulated gene transcription on coactivator PBP but not on PRIP attests to the existence of coactivator selectivity in nuclear receptor function.

  16. The heuristic value of redundancy models of aging.

    PubMed

    Boonekamp, Jelle J; Briga, Michael; Verhulst, Simon

    2015-11-01

    Molecular studies of aging aim to unravel the cause(s) of aging bottom-up, but linking these mechanisms to organismal level processes remains a challenge. We propose that complementary top-down data-directed modelling of organismal level empirical findings may contribute to developing these links. To this end, we explore the heuristic value of redundancy models of aging to develop a deeper insight into the mechanisms causing variation in senescence and lifespan. We start by showing (i) how different redundancy model parameters affect projected aging and mortality, and (ii) how variation in redundancy model parameters relates to variation in parameters of the Gompertz equation. Lifestyle changes or medical interventions during life can modify mortality rate, and we investigate (iii) how interventions that change specific redundancy parameters within the model affect subsequent mortality and actuarial senescence. Lastly, as an example of data-directed modelling and the insights that can be gained from this, (iv) we fit a redundancy model to mortality patterns observed by Mair et al. (2003; Science 301: 1731-1733) in Drosophila that were subjected to dietary restriction and temperature manipulations. Mair et al. found that dietary restriction instantaneously reduced mortality rate without affecting aging, while temperature manipulations had more transient effects on mortality rate and did affect aging. We show that after adjusting model parameters the redundancy model describes both effects well, and a comparison of the parameter values yields a deeper insight in the mechanisms causing these contrasting effects. We see replacement of the redundancy model parameters by more detailed sub-models of these parameters as a next step in linking demographic patterns to underlying molecular mechanisms.

  17. The Effects of Visual-Verbal Redundancy and Recaps on Television News Learning.

    ERIC Educational Resources Information Center

    Son, Jinok; Davie, William

    A study examined the effects of visual-verbal redundancy and recaps on learning from television news. Two factors were used: redundancy between the visual and audio channels, and the presence or absence of a recap. Manipulation of these factors created four conditions: (1) redundant pictures and words plus recap, (2) redundant pictures and words…

  18. Tutorial: Performance and reliability in redundant disk arrays

    NASA Technical Reports Server (NTRS)

    Gibson, Garth A.

    1993-01-01

    A disk array is a collection of physically small magnetic disks that is packaged as a single unit but operates in parallel. Disk arrays capitalize on the availability of small-diameter disks from a price-competitive market to provide the cost, volume, and capacity of current disk systems but many times their performance. Unfortunately, relative to current disk systems, the larger number of components in disk arrays leads to higher rates of failure. To tolerate failures, redundant disk arrays devote a fraction of their capacity to an encoding of their information. This redundant information enables the contents of a failed disk to be recovered from the contents of non-failed disks. The simplest and least expensive encoding for this redundancy, known as N+1 parity is highlighted. In addition to compensating for the higher failure rates of disk arrays, redundancy allows highly reliable secondary storage systems to be built much more cost-effectively than is now achieved in conventional duplicated disks. Disk arrays that combine redundancy with the parallelism of many small-diameter disks are often called Redundant Arrays of Inexpensive Disks (RAID). This combination promises improvements to both the performance and the reliability of secondary storage. For example, IBM's premier disk product, the IBM 3390, is compared to a redundant disk array constructed of 84 IBM 0661 3 1/2-inch disks. The redundant disk array has comparable or superior values for each of the metrics given and appears likely to cost less. In the first section of this tutorial, I explain how disk arrays exploit the emergence of high performance, small magnetic disks to provide cost-effective disk parallelism that combats the access and transfer gap problems. The flexibility of disk-array configurations benefits manufacturer and consumer alike. In contrast, I describe in this tutorial's second half how parallelism, achieved through increasing numbers of components, causes overall failure rates to rise

  19. Factors which Limit the Value of Additional Redundancy in Human Rated Launch Vehicle Systems

    NASA Technical Reports Server (NTRS)

    Anderson, Joel M.; Stott, James E.; Ring, Robert W.; Hatfield, Spencer; Kaltz, Gregory M.

    2008-01-01

    The National Aeronautics and Space Administration (NASA) has embarked on an ambitious program to return humans to the moon and beyond. As NASA moves forward in the development and design of new launch vehicles for future space exploration, it must fully consider the implications that rule-based requirements of redundancy or fault tolerance have on system reliability/risk. These considerations include common cause failure, increased system complexity, combined serial and parallel configurations, and the impact of design features implemented to control premature activation. These factors and others must be considered in trade studies to support design decisions that balance safety, reliability, performance and system complexity to achieve a relatively simple, operable system that provides the safest and most reliable system within the specified performance requirements. This paper describes conditions under which additional functional redundancy can impede improved system reliability. Examples from current NASA programs including the Ares I Upper Stage will be shown.

  20. [The health of industrial employees four years after compulsory redundancy].

    PubMed

    Beale, N; Nethercott, S

    1987-09-01

    A controlled, longitudinal study of the health of workers made redundant when a meat products factory closed has been performed using morbidity data extracted from the records of a group general practice. Increases in consultation rates and the number of visits to hospital outpatient departments in the group made redundant are contrasted with opposite trends in a control group who remained securely employed. As in earlier findings, the increases in morbidity in the study group began when they learned that their jobs were in jeopardy.The subsequent employment history of those made redundant was obtained by questionnaire. In the four years after redundancy, 50 of the 76 men in-the study group found new full-time jobs. The other 26 men remained out of work for most of this time or were made redundant once again. This 'jobless' group consulted their general practitioners 57% more often about 13% more illnesses, were referred to hospital outpatient departments 63% more often and visited hospital 208% more frequently than when enjoying secure employment. During an intervening two-year period of job insecurity, there were increases of 45%, 9%, 25% and 28% respectively, for this jobless group.The implications of these findings for primary care, for the National Health Service and for future research are discussed in the present context of high levels of unemployment.

  1. Working memory capacity and redundant information processing efficiency

    PubMed Central

    Endres, Michael J.; Houpt, Joseph W.; Donkin, Chris; Finn, Peter R.

    2015-01-01

    Working memory capacity (WMC) is typically measured by the amount of task-relevant information an individual can keep in mind while resisting distraction or interference from task-irrelevant information. The current research investigated the extent to which differences in WMC were associated with performance on a novel redundant memory probes (RMP) task that systematically varied the amount of to-be-remembered (targets) and to-be-ignored (distractor) information. The RMP task was designed to both facilitate and inhibit working memory search processes, as evidenced by differences in accuracy, response time, and Linear Ballistic Accumulator (LBA) model estimates of information processing efficiency. Participants (N = 170) completed standard intelligence tests and dual-span WMC tasks, along with the RMP task. As expected, accuracy, response-time, and LBA model results indicated memory search and retrieval processes were facilitated under redundant-target conditions, but also inhibited under mixed target/distractor and redundant-distractor conditions. Repeated measures analyses also indicated that, while individuals classified as high (n = 85) and low (n = 85) WMC did not differ in the magnitude of redundancy effects, groups did differ in the efficiency of memory search and retrieval processes overall. Results suggest that redundant information reliably facilitates and inhibits the efficiency or speed of working memory search, and these effects are independent of more general limits and individual differences in the capacity or space of working memory. PMID:26074828

  2. Avoidance of late abortion.

    PubMed

    1979-11-24

    Induced abortion is now a common procedure in the United States and Britain. Methods for performing induced abortion are reviewed. Menstrual regulation, aspiration with a hand-held syringe and a flexible cannula within 6 weeks of the last period, is not often practiced in Britain. Several developing countries are using this simple technique to advantage. Vacuum aspiration in the 1st 12 weeks of pregnancy is the main method being used everywhere for 1st trimester procedures. Mortality rates with this method are low and, in well-organized clinics with experienced personnel, the rates can be reduced even further. It is agreed that 2nd trimester procedures are more complex, both physically and emotionally. In the last several years, dilatation and evacuation (D&E) has increased in popularity for 2nd trimester procedures. Dilation of the cervix is generally accomplished with laminaria, evacuation of the uterus with forceps, and then suction curettage applied. This procedure has replaced intraamniotic infusion, hysterotomy, and hysterectomy as the most commonly - practiced method, despite its need for special surgical skills and good clinical backup. Follow-up of abortions is difficult. Different long-term effects have been noted with different abortion procedures. Early abortion seems to have only a modest effect, if that. Whether late abortion has long-lasting effects remains open to question. Late abortion should be avoided.

  3. CAT altitude avoidance system

    NASA Technical Reports Server (NTRS)

    Gary, B. L. (Inventor)

    1982-01-01

    A method and apparatus are provided for indicating the altitude of the tropopause or of an inversion layer wherein clear air turbulence (CAT) may occur, and the likely severity of any such CAT, includes directing a passive microwave radiometer on the aircraft at different angles with respect to the horizon. The microwave radiation measured at a frequency of about 55 GHz represents the temperature of the air at an ""average'' range of about 3 kilometers, so that the sine of the angle of the radiometer times 3 kilometers equals the approximate altitude of the air whose temperature is measured. A plot of altitude (with respect to the aircraft) versus temperature of the air at that altitude, can indicate when an inversion layer is present and can indicate the altitude of the tropopause or of such an inversion layer. The plot can also indicate the severity of any CAT in an inversion layer. If CAT has been detected in the general area, then the aircraft can be flown at an altitude to avoid the tropopause or inversion layer.

  4. Cortical inhibition reduces information redundancy at presentation of communication sounds in the primary auditory cortex.

    PubMed

    Gaucher, Quentin; Huetz, Chloé; Gourévitch, Boris; Edeline, Jean-Marc

    2013-06-26

    In all sensory modalities, intracortical inhibition shapes the functional properties of cortical neurons but also influences the responses to natural stimuli. Studies performed in various species have revealed that auditory cortex neurons respond to conspecific vocalizations by temporal spike patterns displaying a high trial-to-trial reliability, which might result from precise timing between excitation and inhibition. Studying the guinea pig auditory cortex, we show that partial blockage of GABAA receptors by gabazine (GBZ) application (10 μm, a concentration that promotes expansion of cortical receptive fields) increased the evoked firing rate and the spike-timing reliability during presentation of communication sounds (conspecific and heterospecific vocalizations), whereas GABAB receptor antagonists [10 μm saclofen; 10-50 μm CGP55845 (p-3-aminopropyl-p-diethoxymethyl phosphoric acid)] had nonsignificant effects. Computing mutual information (MI) from the responses to vocalizations using either the evoked firing rate or the temporal spike patterns revealed that GBZ application increased the MI derived from the activity of single cortical site but did not change the MI derived from population activity. In addition, quantification of information redundancy showed that GBZ significantly increased redundancy at the population level. This result suggests that a potential role of intracortical inhibition is to reduce information redundancy during the processing of natural stimuli. PMID:23804094

  5. Redundant control of migration and adhesion by ERM proteins in vascular smooth muscle cells

    SciTech Connect

    Baeyens, Nicolas; Latrache, Iman; Yerna, Xavier; Noppe, Gauthier; Horman, Sandrine; Morel, Nicole

    2013-11-22

    Highlights: •The three ERM proteins are expressed in vascular smooth muscle cell. •ERM depletion inhibited PDGF-evoked migration redundantly. •ERM depletion increased cell adhesion redundantly. •ERM depletion did not affect PDGF-evoked Ca signal, Rac1 activation, proliferation. •ERM proteins control PDGF-induced migration by regulating adhesion. -- Abstract: Ezrin, radixin, and moesin possess a very similar structure with a C-terminal actin-binding domain and a N-terminal FERM interacting domain. They are known to be involved in cytoskeleton organization in several cell types but their function in vascular smooth muscle cells (VSMC) is still unknown. The aim of this study was to investigate the role of ERM proteins in cell migration induced by PDGF, a growth factor involved in pathophysiological processes like angiogenesis or atherosclerosis. We used primary cultured VSMC obtained from rat aorta, which express the three ERM proteins. Simultaneous depletion of the three ERM proteins with specific siRNAs abolished the effects of PDGF on cell architecture and migration and markedly increased cell adhesion and focal adhesion size, while these parameters were only slightly affected by depletion of ezrin, radixin or moesin alone. Rac1 activation, cell proliferation, and Ca{sup 2+} signal in response to PDGF were unaffected by ERM depletion. These results indicate that ERM proteins exert a redundant control on PDGF-induced VSMC migration by regulating focal adhesion turn-over and cell adhesion to substrate.

  6. Functional redundancy in phenol and toluene degradation in Pseudomonas stutzeri strains isolated from the Baltic Sea.

    PubMed

    Heinaru, Eeva; Naanuri, Eve; Grünbach, Maarja; Jõesaar, Merike; Heinaru, Ain

    2016-09-01

    In the present study we describe functional redundancy of bacterial multicomponent monooxygenases (toluene monooxygenase (TMO) and toluene/xylene monooxygenase (XylAM) of TOL pathway) and cooperative genetic regulation at the expression of the respective catabolic operons by touR and xylR encoded regulatory circuits in five phenol- and toluene-degrading Pseudomonas stutzeri strains. In these strains both toluene degradation pathways (TMO and Xyl) are active and induced by toluene and phenol. The whole genome sequence of the representative strain 2A20 revealed the presence of complete TMO- and Xyl-upper pathway operons together with two sets of lower catechol meta pathway operons, as well as phenol-degrading operon in a single 292,430bp contig. The much lower GC content and analysis of the predicted ORFs refer to the plasmid origin of the approximately 130kb region of this contig, containing the xyl, phe and tou genes. The deduced amino acid sequences of the TMO, XylA and the large subunit of phenol monooxygenase (LmPH) show 98-100% identity with the respective gene products of the strain Pseudomonas sp. OX1. In both strains 2A20 and OX1 the meta-cleavage pathways for catechol degradation are coded by two redundant operons (phe and xyl). We show that in the strain 2A20 TouR and XylR are activated by different effector molecules, phenol and toluene, respectively, and they both control transcription of the xyl upper, tou (TMO) and phe catabolic operons. Although the growth parameters of redundant strains did not show advantage at toluene biodegradation, the functional redundancy could provide better flexibility to the bacteria in environmental conditions. PMID:27185632

  7. Is Avoiding an Aversive Outcome Rewarding? Neural Substrates of Avoidance Learning in the Human Brain

    PubMed Central

    Kim, Hackjin; Shimojo, Shinsuke

    2006-01-01

    Avoidance learning poses a challenge for reinforcement-based theories of instrumental conditioning, because once an aversive outcome is successfully avoided an individual may no longer experience extrinsic reinforcement for their behavior. One possible account for this is to propose that avoiding an aversive outcome is in itself a reward, and thus avoidance behavior is positively reinforced on each trial when the aversive outcome is successfully avoided. In the present study we aimed to test this possibility by determining whether avoidance of an aversive outcome recruits the same neural circuitry as that elicited by a reward itself. We scanned 16 human participants with functional MRI while they performed an instrumental choice task, in which on each trial they chose from one of two actions in order to either win money or else avoid losing money. Neural activity in a region previously implicated in encoding stimulus reward value, the medial orbitofrontal cortex, was found to increase, not only following receipt of reward, but also following successful avoidance of an aversive outcome. This neural signal may itself act as an intrinsic reward, thereby serving to reinforce actions during instrumental avoidance. PMID:16802856

  8. Real-time obstacle avoidance using harmonic potential functions

    NASA Technical Reports Server (NTRS)

    Kim, Jin-Oh; Khosla, Pradeep K.

    1992-01-01

    This paper presents a new formulation of the artificial potential approach to the obstacle avoidance problem for a mobile robot or a manipulator in a known environment. Previous formulations of artificial potentials for obstacle avoidance have exhibited local minima in a cluttered environment. To build an artificial potential field, harmonic functions that completely eliminate local minima even for a cluttered environment are used. The panel method is employed to represent arbitrarily shaped obstacles and to derive the potential over the whole space. Based on this potential function, an elegant control strategy is proposed for the real-time control of a robot. The harmonic potential, the panel method, and the control strategy are tested with a bar-shaped mobile robot and a three-degree-of-freedom planar redundant manipulator.

  9. Collision avoidance sensor skin

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The objective was to totally eliminate the possibility of a robot (or any mechanism for that matter) inducing a collision in space operations. We were particularly concerned that human beings were safe under all circumstances. This was apparently accomplished, and it is shown that GSFC has a system that is ready for space qualification and flight. However, it soon became apparent that much more could be accomplished with this technology. Payloads could be made invulnerable to collision avoidance and the blind spots behind them eliminated. This could be accomplished by a simple, non-imaging set of 'Capaciflector' sensors on each payload. It also is evident that this system could be used to align and dock the system with a wide margin of safety. Throughout, lighting problems could be ignored, and unexpected events and modeling errors taken in stride. At the same time, computational requirements would be reduced. This can be done in a simple, rugged, reliable manner that will not disturb the form factor of space systems. It will be practical for space applications. The lab experiments indicate we are well on the way to accomplishing this. Still, the research trail goes deeper. It now appears that the sensors can be extended to end effectors to provide precontact information and make robot docking (or any docking connection) very smooth, with minimal loads impacted back into the mating structures. This type of ability would be a major step forward in basic control techniques in space. There are, however, baseline and restructuring issues to be tackled. The payloads must get power and signals to them from the robot or from the astronaut servicing tool. This requires a standard electromechanical interface. Any of several could be used. The GSFC prototype shown in this presentation is a good one. Sensors with their attendant electronics must be added to the payloads, end effectors, and robot arms and integrated into the system.

  10. Method of glitch reduction in DAC with weight redundancy

    NASA Astrophysics Data System (ADS)

    Azarov, Olexiy D.; Murashchenko, Olexander G.; Chernyak, Olexander I.; Smolarz, Andrzej; Kashaganova, Gulzhan

    2015-12-01

    The appearance of glitches in digital-to-analog converters leads to significant limitations of conversion accuracy and speed, which is critical for DAC and limits their usage. This paper researches the possibility of using the redundant positional number system in order to reduce glitches in DAC. There had been described the usage pattern of number systems with fractional digit weights of bits as well as with the whole number weights of bits. Hereafter there had been suggested the algorithm for glitches reduction in the DAC generation mode of incessant analogue signal. There had also been estimated the efficiency of weight redundancy application with further presentation of the most efficient parameters of number systems. The paper describes a block diagram of a low-glitch DAC based on Fibonacci codes. The simulation results prove the feasibility of weight redundancy application and show a significant reduction of glitches in DAC in comparison with the classical binary system.

  11. MIMO radar arrays with minimum redundancy: a design method

    NASA Astrophysics Data System (ADS)

    Kirschner, A. J.; Siart, U.; Guetlein, J.; Detlefsen, J.

    2013-10-01

    Coherent multiple-input multiple-output (MIMO) radar systems with co-located antennas, form monostatic vir- tual arrays by discrete convolution of a bistatic setup of transmitters and receivers. Thereby, a trade-off between maximum array dimension, element spacing and hardware efforts exists. In terms of estimating the direction of arrival, the covariance matrix of the array element signals plays an important role. Here, minimum redundancy arrays aim at a hardware reduction with signal reconstruction by exploiting the Toeplitz characteristics of the covariance matrix. However, the discrete spatial convolution complicates the finding of an optimal antenna setup with minimum redundancy. Combinatorial effort is the consequence. This paper presents a possible simplified algorithm in order to find MIMO array setups of maximum dimension with minimum redundancy.

  12. Performance evaluation of redundant disk array support for transaction recovery

    NASA Technical Reports Server (NTRS)

    Mourad, Antoine N.; Fuchs, W. Kent; Saab, Daniel G.

    1991-01-01

    Redundant disk arrays provide a way of achieving rapid recovery from media failures with a relatively low storage cost for large scale data systems requiring high availability. Here, we propose a method for using redundant disk arrays to support rapid recovery from system crashes and transaction aborts in addition to their role in providing media failure recovery. A twin page scheme is used to store the parity information in the array so that the time for transaction commit processing is not degraded. Using an analytical model, we show that the proposed method achieves a significant increase in the throughput of database systems using redundant disk arrays by reducing the number of recovery operations needed to maintain the consistency of the database.

  13. Intelligent redundant actuation system requirements and preliminary system design

    NASA Technical Reports Server (NTRS)

    Defeo, P.; Geiger, L. J.; Harris, J.

    1985-01-01

    Several redundant actuation system configurations were designed and demonstrated to satisfy the stringent operational requirements of advanced flight control systems. However, this has been accomplished largely through brute force hardware redundancy, resulting in significantly increased computational requirements on the flight control computers which perform the failure analysis and reconfiguration management. Modern technology now provides powerful, low-cost microprocessors which are effective in performing failure isolation and configuration management at the local actuator level. One such concept, called an Intelligent Redundant Actuation System (IRAS), significantly reduces the flight control computer requirements and performs the local tasks more comprehensively than previously feasible. The requirements and preliminary design of an experimental laboratory system capable of demonstrating the concept and sufficiently flexible to explore a variety of configurations are discussed.

  14. Control of a serpentine manipulator with collision avoidance

    NASA Technical Reports Server (NTRS)

    Byers, Robert M.

    1993-01-01

    The robotics lab at the Kennedy Space Center is investigating the possibility of using a 'serpentine' manipulator for Shuttle inspection and payload processing. Serpentine manipulators are characterized by a large number of degrees of freedom giving them a high degree of redundancy. This redundancy allows them to be used to reach confined areas while avoiding collisions with their environment. In this paper, the author describes a new approach to controlling the joint rates for an n degree of freedom robot such that it moves its end effector to a desired position while simultaneously avoiding collision of any part of the robot arm with obstacles. Joint rates which move the end effector toward the target are found via a Lyapunov stability function. The gradient of an obstacle cost function indicates the direction toward obstacle collision in the joint space. The component of the end effector joint rates orthogonal to the obstacle gradient becomes the commanded joint rates. A notional eleven DOF model is used to numerically demonstrate the efficacy of the control law.

  15. Inverse kinematics of redundant systems driver IKORv1.0-2.0 (full space parameterization with orientation control, platform mobility, and portability)

    SciTech Connect

    Hacker, C.J.; Fries, G.A.; Pin, F.G.

    1997-01-01

    Few optimization methods exist for path planning of kinematically redundant manipulators. Among these, a universal method is lacking that takes advantage of a manipulator`s redundancy while satisfying possibly varying constraints and task requirements. Full Space Parameterization (FSP) is a new method that generates the entire solution space of underspecified systems of algebraic equations and then calculates the unique solution satisfying specific constraints and optimization criteria. The FSP method has been previously tested on several configurations of the redundant manipulator HERMIES-III. This report deals with the extension of the FSP driver, Inverse Kinematics On Redundant systems (IKOR), to include three-dimensional manipulation systems, possibly incorporating a mobile platform, with and without orientation control. The driver was also extended by integrating two optimized versions of the FSP solution generator as well as the ability to easily port to any manipulator. IKOR was first altered to include the ability to handle orientation control and to integrate an optimized solution generator. The resulting system was tested on a 4 degrees-of-redundancy manipulator arm and was found to successfully perform trajectories with least norm criteria while avoiding obstacles and joint limits. Next, the system was adapted and tested on a manipulator arm placed on a mobile platform yielding 7 degrees of redundancy. After successful testing on least norm trajectories while avoiding obstacles and joint limits, IKORv1.0 was developed. The system was successfully verified using comparisons with a current industry standard, the Moore Penrose Pseudo-Inverse. Finally, IKORv2.0 was created, which includes both the one shot and two step methods, manipulator portability, integration of a second optimized solution generator, and finally a more robust and usable code design.

  16. Redundancy management of electrohydraulic servoactuators by mathematical model referencing

    NASA Technical Reports Server (NTRS)

    Campbell, R. A.

    1971-01-01

    A description of a mathematical model reference system is presented which provides redundancy management for an electrohydraulic servoactuator. The mathematical model includes a compensation network that calculates reference parameter perturbations induced by external disturbance forces. This is accomplished by using the measured pressure differential data taken from the physical system. This technique was experimentally verified by tests performed using the H-1 engine thrust vector control system for Saturn IB. The results of these tests are included in this report. It was concluded that this technique improves the tracking accuracy of the model reference system to the extent that redundancy management of electrohydraulic servosystems may be performed using this method.

  17. F-8 DFBW sensor failure identification using analytic redundancy

    NASA Technical Reports Server (NTRS)

    Deckert, J. C.; Desai, M. N.; Deyst, J. J.; Willsky, A. S.

    1977-01-01

    The structure of a sensor failure detection and identification system designed for the NASA F-8 DFBW aircraft is outlined. The system is for use in a dual-redundant environment, and it takes maximal advantage of all functional relationships among the sensed variables. The identification logic uses the quality sequential probability ratio, which provides a useful on-line measure of confidence in the various forms of analytic redundancy. Preliminary simulation results indicate good behavior of the analytic decision statistic, based on the sequential probability ratio test.

  18. Fault tolerant kinematic control of hyper-redundant manipulators

    NASA Technical Reports Server (NTRS)

    Bedrossian, Nazareth S.

    1994-01-01

    Hyper-redundant spatial manipulators possess fault-tolerant features because of their redundant structure. The kinematic control of these manipulators is investigated with special emphasis on fault-tolerant control. The manipulator tasks are viewed in the end-effector space while actuator commands are in joint-space, requiring an inverse kinematic algorithm to generate joint-angle commands from the end-effector ones. The rate-inverse kinematic control algorithm presented in this paper utilizes the pseudoinverse to accommodate for joint motor failures. An optimal scale factor for the robust inverse is derived.

  19. Kinematically redundant arm formulations for coordinated multiple arm implementations

    NASA Technical Reports Server (NTRS)

    Bailey, Robert W.; Quiocho, Leslie J.; Cleghorn, Timothy F.

    1990-01-01

    Although control laws for kinematically redundant robotic arms were presented as early as 1969, redundant arms have only recently become recognized as viable solutions to limitations inherent to kinematically sufficient arms. The advantages of run-time control optimization and arm reconfiguration are becoming increasingly attractive as the complexity and criticality of robotic systems continues to progress. A generalized control law for a spatial arm with 7 or more degrees of freedom (DOF) based on Whitney's resolved rate formulation is given. Results from a simulation implementation utilizing this control law are presented. Furthermore, results from a two arm simulation are presented to demonstrate the coordinated control of multiple arms using this formulation.

  20. Redundancy in information transmission in a two-step cascade

    NASA Astrophysics Data System (ADS)

    Biswas, Ayan; Banik, Suman K.

    2016-05-01

    We present a stochastic framework to study signal transmission in a generic two-step cascade S→X→Y . Starting from a set of Langevin equations obeying Gaussian noise processes we calculate the variance and covariance while considering both linear and nonlinear production terms for different biochemical species of the cascade. These quantities are then used to calculate the net synergy within the purview of partial information decomposition. We show that redundancy in information transmission is essentially an important consequence of Markovian property of the two-step cascade motif. We also show that redundancy increases fidelity of the signaling pathway.

  1. Redundancy in information transmission in a two-step cascade.

    PubMed

    Biswas, Ayan; Banik, Suman K

    2016-05-01

    We present a stochastic framework to study signal transmission in a generic two-step cascade S→X→Y. Starting from a set of Langevin equations obeying Gaussian noise processes we calculate the variance and covariance while considering both linear and nonlinear production terms for different biochemical species of the cascade. These quantities are then used to calculate the net synergy within the purview of partial information decomposition. We show that redundancy in information transmission is essentially an important consequence of Markovian property of the two-step cascade motif. We also show that redundancy increases fidelity of the signaling pathway.

  2. Certificated sickness absence in industrial employees threatened with redundancy.

    PubMed

    Beale, N; Nethercott, S

    1988-05-28

    The proposition that workers take less sick leave when threatened by redundancy was examined in a longitudinal, controlled study using information from case records in a general practice. The hypothesis was only partly supported--certificated sickness absence dropped only in employees under the age of 40. Workers fearing job loss reported more illness, and their periods of absence were significantly longer, especially for men and for workers who had previously consulted their general practitioner infrequently. This study provides further evidence that the fear of mass redundancy is stressful to workers so threatened and costly to a society experiencing rising unemployment.

  3. Redundant information from thermal illumination: quantum Darwinism in scattered photons

    NASA Astrophysics Data System (ADS)

    Jess Riedel, C.; Zurek, Wojciech H.

    2011-07-01

    We study quantum Darwinism, the redundant recording of information about the preferred states of a decohering system by its environment, for an object illuminated by a blackbody. We calculate the quantum mutual information between the object and its photon environment for blackbodies that cover an arbitrary section of the sky. In particular, we demonstrate that more extended sources have a reduced ability to create redundant information about the system, in agreement with previous evidence that initial mixedness of an environment slows—but does not stop—the production of records. We also show that the qualitative results are robust for more general initial states of the system.

  4. Site Partitioning for Redundant Arrays of Distributed Disks

    NASA Technical Reports Server (NTRS)

    Mourad, Antoine N.; Fuchs, W. Kent; Saab, Daniel G.

    1996-01-01

    Redundant arrays of distributed disks (RADD) can be used in a distributed computing system or database system to provide recovery in the presence of disk crashes and temporary and permanent failures of single sites. In this paper, we look at the problem of partitioning the sites of a distributed storage system into redundant arrays in such a way that the communication costs for maintaining the parity information are minimized. We show that the partitioning problem is NP-hard. We then propose and evaluate several heuristic algorithms for finding approximate solutions. Simulation results show that significant reduction in remote parity update costs can be achieved by optimizing the site partitioning scheme.

  5. Robust and cooperative image-based visual servoing system using a redundant architecture.

    PubMed

    Garcia-Aracil, Nicolas; Perez-Vidal, Carlos; Sabater, Jose Maria; Morales, Ricardo; Badesa, Francisco J

    2011-01-01

    The reliability and robustness of image-based visual servoing systems is still unsolved by the moment. In order to address this issue, a redundant and cooperative 2D visual servoing system based on the information provided by two cameras in eye-in-hand/eye-to-hand configurations is proposed. Its control law has been defined to assure that the whole system is stable if each subsystem is stable and to allow avoiding typical problems of image-based visual servoing systems like task singularities, features extraction errors, disappearance of image features, local minima, etc. Experimental results with an industrial robot manipulator based on Schunk modular motors to demonstrate the stability, performance and robustness of the proposed system are presented.

  6. Force-reflecting control of a teleoperated system coupling a nonredundant master with a redundant slave

    SciTech Connect

    Kress, R.; Jansen, J.; DePiero, F.; Babcock, S.

    1990-01-01

    A bilateral, force-reflecting controller was formulated for a 6- Degree-of-Freedom (6-DOF) master operating a 7-DOF slave. Six degrees of freedom are required to arbitrarily position and orient a manipulator and effector. A 7-DOF slave manipulator is desirable because the additional (or redundant) degree of freedom potentially allows for an infinite number of manipulator configurations for a given end effector position and orientation, thus permitting the manipulator to reach around obstacles to perform a task, to avoid joint limits, or to optimize its confinguration in some other manner. A master/slave control system was formulated using a stiffness controller for the master and a gradient-projection algorithm for the slave. The complete control system provides scaled position tracking and indexing between slave and master and force reflection between master and slave. 11 refs., 1 fig.

  7. A fully redundant double difference algorithm for obtaining minimum variance estimates from GPS observations

    NASA Technical Reports Server (NTRS)

    Melbourne, William G.

    1986-01-01

    In double differencing a regression system obtained from concurrent Global Positioning System (GPS) observation sequences, one either undersamples the system to avoid introducing colored measurement statistics, or one fully samples the system incurring the resulting non-diagonal covariance matrix for the differenced measurement errors. A suboptimal estimation result will be obtained in the undersampling case and will also be obtained in the fully sampled case unless the color noise statistics are taken into account. The latter approach requires a least squares weighting matrix derived from inversion of a non-diagonal covariance matrix for the differenced measurement errors instead of inversion of the customary diagonal one associated with white noise processes. Presented is the so-called fully redundant double differencing algorithm for generating a weighted double differenced regression system that yields equivalent estimation results, but features for certain cases a diagonal weighting matrix even though the differenced measurement error statistics are highly colored.

  8. Robust and cooperative image-based visual servoing system using a redundant architecture.

    PubMed

    Garcia-Aracil, Nicolas; Perez-Vidal, Carlos; Sabater, Jose Maria; Morales, Ricardo; Badesa, Francisco J

    2011-01-01

    The reliability and robustness of image-based visual servoing systems is still unsolved by the moment. In order to address this issue, a redundant and cooperative 2D visual servoing system based on the information provided by two cameras in eye-in-hand/eye-to-hand configurations is proposed. Its control law has been defined to assure that the whole system is stable if each subsystem is stable and to allow avoiding typical problems of image-based visual servoing systems like task singularities, features extraction errors, disappearance of image features, local minima, etc. Experimental results with an industrial robot manipulator based on Schunk modular motors to demonstrate the stability, performance and robustness of the proposed system are presented. PMID:22247698

  9. Effects of post-training infusions of a mitogen-activated protein kinase kinase inhibitor into the hippocampus or entorhinal cortex on short- and long-term retention of inhibitory avoidance.

    PubMed

    Walz, R; Roesler, R; Barros, D M; de Souza, M M; Rodrigues, C; Sant'Anna, M K; Quevedo, J; Choi, H K; Neto, W P; DeDavid e Silva, T L; Medina, J H; Izquierdo, I

    1999-12-01

    We recently demonstrated the time-dependent impairment of long-term retention of a step-down inhibitory avoidance task in rats induced by post-training infusion of the specific MAPKK (mitogen-activated protein kinase kinase) inhibitor PD 098059 into the hippocampus (HIP), amygdala (AMY), entorhinal cortex (EC) and posterior parietal cortex (PPC). Here we investigate the role of the MAPK cascade in the HIP and the EC on both short- and long-term retention of inhibitory avoidance in rats, using three different doses of the MAPKK inhibitor PD 098059. Adult male Wistar rats were trained and tested in inhibitory avoidance and given an infusion of PD 098059 (0.5, 5.0 or 50.0 microM) at 0, 30, 90, 120, 180, 270 or 360 min after training. A retention test session was carried out at 90, 180 or 270 min after training (short-term memory, STM) and/ or 24 h after training (long-term memory, LTM). When infused into the HIP at 0 min, but not at 30, 90, 120 or 180 min after training, PD 098059 impaired STM. Intrahippocampal PD 098059 impaired LTM when infused at 180 min, but not at 0, 30, 90, 120 or 270 min after training. When infused into the EC, PD 098059 enhanced STM when given at 0 min after training and had no effect when given at 30, 90, 120 or 180 min after training. In this structure, PD 098059 impaired LTM when given at 180 or 270 min, but not at 30, 90, 120 or 360 min after training. All effects were dose-dependent. These findings indicate that the MAPK cascade in the HIP and EC is differentially involved in short- and long-term retention of inhibitory avoidance in rats.

  10. Fission Yeast Exo1 and Rqh1-Dna2 Redundantly Contribute to Resection of Uncapped Telomeres

    PubMed Central

    Nanbu, Tomoko; Nguyễn, Luân C.; Habib, Ahmed G. K.; Hirata, Naoya; Ukimori, Shinobu; Tanaka, Daiki; Masuda, Kenta; Takahashi, Katsunori; Yukawa, Masashi; Tsuchiya, Eiko; Ueno, Masaru

    2015-01-01

    The uncapping of telomeres induces a DNA damage response. In Schizosaccharomyces pombe, deletion of pot1+ causes telomere uncapping and rapid telomere resection, resulting in chromosome fusion. Using the nmt-pot1-aid strain, we previously reported that Pot1 shut-off causes telomere loss and chromosome fusion in S. pombe. However, the factors responsible for the resection of uncapped telomeres remain unknown. In this study, we investigated these factors and found that concomitant deletion of rqh1+ and exo1+ alleviated the loss of telomeres following Pot1 shut-off, suggesting that Rqh1 and Exo1 are redundantly involved in the resection of uncapped telomeres. We also investigated the role of Rqh1 helicase activity and found it to be essential for the resection of uncapped telomeres. Moreover, we found that Dna2 and Exo1 function redundantly in the resection of uncapped telomeres. Taken together, these results suggest that Exo1 and Rqh1-Dna2 redundantly contribute to the resection of uncapped telomeres. Therefore, our results demonstrate that nmt-pot1-aid is an important model strain to study the role of helicases and nucleases in the resection of uncapped telomeres and to improve our understanding of DNA double-strand break repair. PMID:26465752

  11. Redundancy in regulation of chondrogenesis in MIA/CD-RAP-deficient mice.

    PubMed

    Schmid, Rainer; Bosserhoff, Anja-Katrin

    2014-02-01

    Recent in vitro analysis of MIA/CD-RAP-deficient (MIA(-/-)) mesenchymal stem cells revealed altered chondrogenic differentiation, characterised by enhanced proliferation and delayed differentiation. However, adult MIA(-/-) mice develop normally and show only ultrastructural defects of the cartilage but no major abnormalities. We therefore focused, in this study, on chondrogenesis in vivo in MIA(-/-) mouse embryos to reveal potential molecular changes during embryogenesis and possible redundant mechanisms, which explain the almost normal phenotype despite MIA/CD-RAP loss. In situ hybridisation analysis revealed larger expression areas of Col2a1 and Sox9 positive, proliferating chondrocytes at day 15.5 and 16.5 of embryogenesis in MIA(-/-) mice. The initially diminished zone of Col10a1-expressing hypertrophic chondrocytes at day 15.5 was compensated at day 16.5 in MIA(-/-) embryos. Supported by in vitro studies using mesenchymal stem cells, we discovered that chondrogenesis in MIA(-/-) mice is modified by enhanced Sox9, Sox6 and AP-2α expression. Finally, we identified reduced AP1 and CRE activity, analysed by reporter gene- and electrophoretic mobility shift assays, important for redundancy mechanism which rescued delayed hypertrophic differentiation and allows normal development of MIA(-/-) mice. In summary, as observed in other knockout models of molecules important for cartilage development and differentiation, viability and functional integrity is reached by remarkable molecular redundancy in MIA/CD-RAP knockout mice.

  12. Lipoprotein Receptors Redundantly Participate in Entry of Hepatitis C Virus

    PubMed Central

    Ono, Chikako; Uemura, Kentaro; Kawachi, Yukako; Shiokawa, Mai; Mori, Hiroyuki; Wada, Masami; Shima, Ryoichi; Okamoto, Toru; Hiraga, Nobuhiko; Suzuki, Ryosuke; Chayama, Kazuaki; Wakita, Takaji; Matsuura, Yoshiharu

    2016-01-01

    Scavenger receptor class B type 1 (SR-B1) and low-density lipoprotein receptor (LDLR) are known to be involved in entry of hepatitis C virus (HCV), but their precise roles and their interplay are not fully understood. In this study, deficiency of both SR-B1 and LDLR in Huh7 cells was shown to impair the entry of HCV more strongly than deficiency of either SR-B1 or LDLR alone. In addition, exogenous expression of not only SR-B1 and LDLR but also very low-density lipoprotein receptor (VLDLR) rescued HCV entry in the SR-B1 and LDLR double-knockout cells, suggesting that VLDLR has similar roles in HCV entry. VLDLR is a lipoprotein receptor, but the level of its hepatic expression was lower than those of SR-B1 and LDLR. Moreover, expression of mutant lipoprotein receptors incapable of binding to or uptake of lipid resulted in no or slight enhancement of HCV entry in the double-knockout cells, suggesting that binding and/or uptake activities of lipid by lipoprotein receptors are essential for HCV entry. In addition, rescue of infectivity in the double-knockout cells by the expression of the lipoprotein receptors was not observed following infection with pseudotype particles bearing HCV envelope proteins produced in non-hepatic cells, suggesting that lipoproteins associated with HCV particles participate in the entry through their interaction with lipoprotein receptors. Buoyant density gradient analysis revealed that HCV utilizes these lipoprotein receptors in a manner dependent on the lipoproteins associated with HCV particles. Collectively, these results suggest that lipoprotein receptors redundantly participate in the entry of HCV. PMID:27152966

  13. Disconnecting the Yin and Yang Relation of Epidermal Growth Factor Receptor (EGFR)-Mediated Delivery: A Fully Synthetic, EGFR-Targeted Gene Transfer System Avoiding Receptor Activation

    PubMed Central

    Schäfer, A.; Pahnke, A.; Schaffert, D.; van Weerden, W.M.; de Ridder, C.M.A.; Rödl, W.; Vetter, A.; Spitzweg, C.; Kraaij, R.; Wagner, E.

    2011-01-01

    Abstract The epidermal growth factor receptor (EGFR) is upregulated within a high percentage of solid tumors and hence is an attractive target for tumor-targeted therapies including gene therapy. The natural EGFR ligand epidermal growth factor (EGF) has been used for this purpose, despite the risk of mitogenic effects due to EGFR activation. We have developed a fully synthetic, EGFR-targeted gene delivery system based on PEGylated linear polyethylenimine (LPEI), allowing evaluation of different EGFR-binding peptides in terms of transfection efficiency and EGFR activation. Peptide sequences directly derived from the human EGF molecule enhanced transfection efficiency with concomitant EGFR activation. Only the EGFR-binding peptide GE11, which has been identified by phage display technique, showed specific enhancement of transfection on EGFR-overexpressing tumor cells including glioblastoma and hepatoma, but without EGFR activation. EGFR targeting led to high levels of cell association of fluorescently labeled polyplexes after only 30 min of incubation. EGF pretreatment of cells induced enhanced cellular internalization of all polyplex types tested, pointing at generally enhanced macropinocytosis. EGF polyplexes diminished cell surface expression of EGFR for up to 4 hr, whereas GE11 polyplexes did not. In a clinically relevant orthotopic prostate cancer model, intratumorally injected GE11 polyplexes were superior in inducing transgene expression when compared with untargeted polyplexes. PMID:21644815

  14. Temporary Redundant Transmission Mechanism for SCTP Multihomed Hosts

    PubMed Central

    Mohana Geetha, D.; Muthusundar, S. K.; Subramaniam, M.; Ayyaswamy, Kathirvel

    2015-01-01

    In SCTP's Concurrent Multipath Transfer, if data is sent to the destined IP(s) without knowledge of the paths condition, packets may be lost or delayed. This is because of the bursty nature of IP traffic and physical damage to the network. To offset these problems, network path status is examined using our new mechanism Multipath State Aware Concurrent Multipath Transfer using redundant transmission (MSACMT-RTv2). Here the status of multiple paths is analyzed, initially and periodically thereafter transmitted. After examination, paths priority is assigned before transmission. One path is temporarily employed as redundant path for the failure-expected path (FEP); this redundant path is used for transmitting redundant data. At the end of predefined period, reliability of the FEP is confirmed. If FEP is ensured to be reliable, temporary path is transformed into normal CMT path. MSACMT-RTv2 algorithm is simulated using the Delaware University ns-2 SCTP/CMT module (ns-2; V2.29). We present and discuss MSACMT-RTv2 performance in asymmetric path delay and with finite receiver buffer (rbuf) size. We extended our experiment to test robustness of this algorithm and inferred exhaustive result. It is inferred that our algorithm outperforms better in terms of increasing the throughput and reducing the latency than existing system. PMID:25685833

  15. Redundancy and Novelty Mining in the Business Blogosphere

    ERIC Educational Resources Information Center

    Tsai, Flora S.; Chan, Kap Luk

    2010-01-01

    Purpose: The paper aims to explore the performance of redundancy and novelty mining in the business blogosphere, which has not been studied before. Design/methodology/approach: Novelty mining techniques are implemented to single out novel information out of a massive set of text documents. This paper adopted the mixed metric approach which…

  16. Parameter redundancy in discrete state‐space and integrated models

    PubMed Central

    McCrea, Rachel S.

    2016-01-01

    Discrete state‐space models are used in ecology to describe the dynamics of wild animal populations, with parameters, such as the probability of survival, being of ecological interest. For a particular parametrization of a model it is not always clear which parameters can be estimated. This inability to estimate all parameters is known as parameter redundancy or a model is described as nonidentifiable. In this paper we develop methods that can be used to detect parameter redundancy in discrete state‐space models. An exhaustive summary is a combination of parameters that fully specify a model. To use general methods for detecting parameter redundancy a suitable exhaustive summary is required. This paper proposes two methods for the derivation of an exhaustive summary for discrete state‐space models using discrete analogues of methods for continuous state‐space models. We also demonstrate that combining multiple data sets, through the use of an integrated population model, may result in a model in which all parameters are estimable, even though models fitted to the separate data sets may be parameter redundant. PMID:27362826

  17. Sensor failure detection for jet engines using analytical redundancy

    NASA Technical Reports Server (NTRS)

    Merrill, W. C.

    1984-01-01

    Analytical redundant sensor failure detection, isolation and accommodation techniques for gas turbine engines are surveyed. Both the theoretical technonlogy base and demonstrated concepts are discussed. Also included is a discussion of current technology needs and angoing Government sponsored programs to meet those needs.

  18. Inhibition and Language Pragmatic View in Redundant Data Problem Solving

    ERIC Educational Resources Information Center

    Setti, Annalisa; Caramelli, Nicoletta

    2007-01-01

    The present study concerns redundant data problems, defined as problems in which irrelevant data is provided. This type of problem provides a misleading context [Pascual-Leone, J. (1987). Organismic process for neo-Piagetian theories: A dialectical causal account of cognitive development. "International Journal of Psychology," 22, 531-570] similar…

  19. Controlling Split Attention and Redundancy in Physical Therapy Instruction

    ERIC Educational Resources Information Center

    Pociask, Fredrick D.; Morrison, Gary R.

    2008-01-01

    In this study, we examined the effectiveness of instructional materials designed to control redundancy and split attention in the teaching of complex orthopedic physical therapy skills. Participants included 41 first-year physical therapy students. The modified instruction group received a modified unit of instruction designed to reduce cognitive…

  20. Redundancy of the genetic code enables translational pausing.

    PubMed

    D'Onofrio, David J; Abel, David L

    2014-01-01

    The codon redundancy ("degeneracy") found in protein-coding regions of mRNA also prescribes Translational Pausing (TP). When coupled with the appropriate interpreters, multiple meanings and functions are programmed into the same sequence of configurable switch-settings. This additional layer of Ontological Prescriptive Information (PIo) purposely slows or speeds up the translation-decoding process within the ribosome. Variable translation rates help prescribe functional folding of the nascent protein. Redundancy of the codon to amino acid mapping, therefore, is anything but superfluous or degenerate. Redundancy programming allows for simultaneous dual prescriptions of TP and amino acid assignments without cross-talk. This allows both functions to be coincident and realizable. We will demonstrate that the TP schema is a bona fide rule-based code, conforming to logical code-like properties. Second, we will demonstrate that this TP code is programmed into the supposedly degenerate redundancy of the codon table. We will show that algorithmic processes play a dominant role in the realization of this multi-dimensional code. PMID:24904640

  1. Redundancy of the genetic code enables translational pausing

    PubMed Central

    D'Onofrio, David J.; Abel, David L.

    2014-01-01

    The codon redundancy (“degeneracy”) found in protein-coding regions of mRNA also prescribes Translational Pausing (TP). When coupled with the appropriate interpreters, multiple meanings and functions are programmed into the same sequence of configurable switch-settings. This additional layer of Ontological Prescriptive Information (PIo) purposely slows or speeds up the translation-decoding process within the ribosome. Variable translation rates help prescribe functional folding of the nascent protein. Redundancy of the codon to amino acid mapping, therefore, is anything but superfluous or degenerate. Redundancy programming allows for simultaneous dual prescriptions of TP and amino acid assignments without cross-talk. This allows both functions to be coincident and realizable. We will demonstrate that the TP schema is a bona fide rule-based code, conforming to logical code-like properties. Second, we will demonstrate that this TP code is programmed into the supposedly degenerate redundancy of the codon table. We will show that algorithmic processes play a dominant role in the realization of this multi-dimensional code. PMID:24904640

  2. 109. REDUNDANCY SYSTEM CONTROLS FOR UMBILICAL MAST RETRACTION AT LOWER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    109. REDUNDANCY SYSTEM CONTROLS FOR UMBILICAL MAST RETRACTION AT LOWER LEFT SIDE OF HYDRAULIC CONTROL PANEL IN UMBILICAL MAST PUMP ROOM (109), LSB (BLDG. 770) - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  3. 126. REDUNDANCY SYSTEM CONTROLS FOR UMBILICAL MAST RETRACTION AT LOWER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    126. REDUNDANCY SYSTEM CONTROLS FOR UMBILICAL MAST RETRACTION AT LOWER LEFT SIDE OF HYDRAULIC CONTROL PANEL IN UMBILICAL MAST PUMP ROOM (209), LSB (BLDG. 751) - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  4. Detailed Test Plan Redundant Sensor Strapdown IMU Evaluation Program

    NASA Technical Reports Server (NTRS)

    Hartwell, T.; Miyatake, Y.; Wedekind, D. E.

    1971-01-01

    The test plan for a redundant sensor strapdown inertial measuring unit evaluation program is presented. The subjects discussed are: (1) test philosophy and limitations, (2) test sequence, (3) equipment specifications, (4) general operating procedures, (5) calibration procedures, (6) alignment test phase, and (7) navigation test phase. The data and analysis requirements are analyzed.

  5. Reducing Verbal Redundancy in Multimedia Learning: An Undesired Desirable Difficulty?

    ERIC Educational Resources Information Center

    Yue, Carole L.; Bjork, Elizabeth Ligon; Bjork, Robert A.

    2013-01-01

    Previous research on the redundancy principle in multimedia learning has shown that although exact correspondence between on-screen text and narration generally impairs learning, brief labels within an animation can improve learning. To clarify and extend the theoretical and practical implications of these results, the authors of the present…

  6. Parameter redundancy in discrete state-space and integrated models.

    PubMed

    Cole, Diana J; McCrea, Rachel S

    2016-09-01

    Discrete state-space models are used in ecology to describe the dynamics of wild animal populations, with parameters, such as the probability of survival, being of ecological interest. For a particular parametrization of a model it is not always clear which parameters can be estimated. This inability to estimate all parameters is known as parameter redundancy or a model is described as nonidentifiable. In this paper we develop methods that can be used to detect parameter redundancy in discrete state-space models. An exhaustive summary is a combination of parameters that fully specify a model. To use general methods for detecting parameter redundancy a suitable exhaustive summary is required. This paper proposes two methods for the derivation of an exhaustive summary for discrete state-space models using discrete analogues of methods for continuous state-space models. We also demonstrate that combining multiple data sets, through the use of an integrated population model, may result in a model in which all parameters are estimable, even though models fitted to the separate data sets may be parameter redundant.

  7. Sensor failure detection for jet engines using analytical redundance

    NASA Technical Reports Server (NTRS)

    Merrill, W. C.

    1984-01-01

    Analytical redundant sensor failure detection, isolation and accommodation techniques for gas turbine engines are surveyed. Both the theoretical technology base and demonstrated concepts are discussed. Also included is a discussion of current technology needs and ongoing Government sponsored programs to meet those needs.

  8. The bliss (not the problem) of motor abundance (not redundancy).

    PubMed

    Latash, Mark L

    2012-03-01

    Motor control is an area of natural science exploring how the nervous system interacts with other body parts and the environment to produce purposeful, coordinated actions. A central problem of motor control-the problem of motor redundancy-was formulated by Nikolai Bernstein as the problem of elimination of redundant degrees-of-freedom. Traditionally, this problem has been addressed using optimization methods based on a variety of cost functions. This review draws attention to a body of recent findings suggesting that the problem has been formulated incorrectly. An alternative view has been suggested as the principle of abundance, which considers the apparently redundant degrees-of-freedom as useful and even vital for many aspects of motor behavior. Over the past 10 years, dozens of publications have provided support for this view based on the ideas of synergic control, computational apparatus of the uncontrolled manifold hypothesis, and the equilibrium-point (referent configuration) hypothesis. In particular, large amounts of "good variance"-variance in the space of elements that has no effect on the overall performance-have been documented across a variety of natural actions. "Good variance" helps an abundant system to deal with secondary tasks and unexpected perturbations; its amount shows adaptive modulation across a variety of conditions. These data support the view that there is no problem of motor redundancy; there is bliss of motor abundance. PMID:22246105

  9. Redundancy Effect on Retention of Vocabulary Words Using Multimedia Presentation

    ERIC Educational Resources Information Center

    Samur, Yavuz

    2012-01-01

    This study was designed to examine the effect of the redundancy principle in a multimedia presentation constructed for foreign language vocabulary learning on undergraduate students' retention. The underlying hypothesis of this study is that when the students are exposed to the material in multiple ways through animation, concurrent narration,…

  10. 75 FR 65238 - Loan Guaranty: Elimination of Redundant Regulations; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-22

    ... electronic reporting system. At that time, we failed to update the cross-reference citations within the... of Veterans Affairs (VA) published a document in the Federal Register on June 15, 2010 (75 FR 33704... INFORMATION: On June 15, 2010 (75 FR 33704), VA amended 38 CFR part 36 to eliminate redundant and...

  11. The Effect of Redundant Text in Multimedia Instruction

    ERIC Educational Resources Information Center

    Jamet, Eric; Le Bohec, Olivier

    2007-01-01

    The purpose of this study was to examine the redundancy effects obtained when spoken information was duplicated in writing during the learning of a multimedia document. Documents consisting of diagrams and spoken information on the development of memory models were presented to three groups of students. In the first group, no written text was…

  12. Stimulus conflict triggers behavioral avoidance.

    PubMed

    Dignath, David; Eder, Andreas B

    2015-12-01

    According to a recent extension of the conflict-monitoring theory, conflict between two competing response tendencies is registered as an aversive event and triggers a motivation to avoid the source of conflict. In the present study, we tested this assumption. Over five experiments, we examined whether conflict is associated with an avoidance motivation and whether stimulus conflict or response conflict triggers an avoidance tendency. Participants first performed a color Stroop task. In a subsequent motivation test, participants responded to Stroop stimuli with approach- and avoidance-related lever movements. These results showed that Stroop-conflict stimuli increased the frequency of avoidance responses in a free-choice motivation test, and also increased the speed of avoidance relative to approach responses in a forced-choice test. High and low proportions of response conflict in the Stroop task had no effect on avoidance in the motivation test. Avoidance of conflict was, however, obtained even with new conflict stimuli that had not been presented before in a Stroop task, and when the Stroop task was replaced with an unrelated filler task. Taken together, these results suggest that stimulus conflict is sufficient to trigger avoidance.

  13. Healthcare avoidance: a critical review.

    PubMed

    Byrne, Sharon K

    2008-01-01

    The purpose of this study is to provide a critical review and synthesis of theoretical and research literature documenting the impact of avoidance on healthcare behaviors, identify the factors that influence healthcare avoidance and delay in the adult population, and propose a direction for future research. The Theory of Reasoned Action, Theory of Planned Behavior, Theory of Care-Seeking Behavior, the Transtheoretical Model, and the Behavioral Model of Health Services Use/Utilization are utilized to elaborate on the context within which individual intention to engage in healthcare behaviors occurs. Research literature on the concept of healthcare avoidance obtained by using computerized searches of CINAHL, MEDLINE, PSYCH INFO, and HAPI databases, from 1995 to 2007, were reviewed. Studies were organized by professional disciplines. Healthcare avoidance is a common and highly variable experience. Multiple administrative, demographic, personal, and provider factors are related to healthcare avoidance, for example, distrust of providers and/or the science community, health beliefs, insurance status, or socioeconomic/income level. Although the concept is recognized by multiple disciplines, limited research studies address its impact on healthcare decision making. More systematic research is needed to determine correlates of healthcare avoidance. Such studies will help investigators identify patients at risk for avoidant behaviors and provide the basis for health-promoting interventions. Methodological challenges include identification of characteristics of individuals and environments that hinder healthcare behaviors, as well as, the complexity of measuring healthcare avoidance. Studies need to systematically explore the influence of avoidance behaviors on specific healthcare populations at risk.

  14. Stimulus conflict triggers behavioral avoidance.

    PubMed

    Dignath, David; Eder, Andreas B

    2015-12-01

    According to a recent extension of the conflict-monitoring theory, conflict between two competing response tendencies is registered as an aversive event and triggers a motivation to avoid the source of conflict. In the present study, we tested this assumption. Over five experiments, we examined whether conflict is associated with an avoidance motivation and whether stimulus conflict or response conflict triggers an avoidance tendency. Participants first performed a color Stroop task. In a subsequent motivation test, participants responded to Stroop stimuli with approach- and avoidance-related lever movements. These results showed that Stroop-conflict stimuli increased the frequency of avoidance responses in a free-choice motivation test, and also increased the speed of avoidance relative to approach responses in a forced-choice test. High and low proportions of response conflict in the Stroop task had no effect on avoidance in the motivation test. Avoidance of conflict was, however, obtained even with new conflict stimuli that had not been presented before in a Stroop task, and when the Stroop task was replaced with an unrelated filler task. Taken together, these results suggest that stimulus conflict is sufficient to trigger avoidance. PMID:25931151

  15. Healthcare avoidance: a critical review.

    PubMed

    Byrne, Sharon K

    2008-01-01

    The purpose of this study is to provide a critical review and synthesis of theoretical and research literature documenting the impact of avoidance on healthcare behaviors, identify the factors that influence healthcare avoidance and delay in the adult population, and propose a direction for future research. The Theory of Reasoned Action, Theory of Planned Behavior, Theory of Care-Seeking Behavior, the Transtheoretical Model, and the Behavioral Model of Health Services Use/Utilization are utilized to elaborate on the context within which individual intention to engage in healthcare behaviors occurs. Research literature on the concept of healthcare avoidance obtained by using computerized searches of CINAHL, MEDLINE, PSYCH INFO, and HAPI databases, from 1995 to 2007, were reviewed. Studies were organized by professional disciplines. Healthcare avoidance is a common and highly variable experience. Multiple administrative, demographic, personal, and provider factors are related to healthcare avoidance, for example, distrust of providers and/or the science community, health beliefs, insurance status, or socioeconomic/income level. Although the concept is recognized by multiple disciplines, limited research studies address its impact on healthcare decision making. More systematic research is needed to determine correlates of healthcare avoidance. Such studies will help investigators identify patients at risk for avoidant behaviors and provide the basis for health-promoting interventions. Methodological challenges include identification of characteristics of individuals and environments that hinder healthcare behaviors, as well as, the complexity of measuring healthcare avoidance. Studies need to systematically explore the influence of avoidance behaviors on specific healthcare populations at risk. PMID:18758277

  16. Neuroimaging the temporal dynamics of human avoidance to sustained threat.

    PubMed

    Schlund, Michael W; Hudgins, Caleb D; Magee, Sandy; Dymond, Simon

    2013-11-15

    Many forms of human psychopathology are characterized by sustained negative emotional responses to threat and chronic behavioral avoidance, implicating avoidance as a potential transdiagnostic factor. Evidence from both nonhuman neurophysiological and human neuroimaging studies suggests a distributed frontal-limbic-striatal brain network supports avoidance. However, our understanding of the temporal dynamics of the network to sustained threat that prompts sustained avoidance is limited. To address this issue, 17 adults were given extensive training on a modified free-operant avoidance task in which button pressing avoided money loss during a sustained threat period. Subsequently, subjects underwent functional magnetic resonance imaging while completing the avoidance task. In our regions of interest, we observed phasic, rather than sustained, activation during sustained threat in dorsolateral and inferior frontal regions, anterior and dorsal cingulate, ventral striatum and regions associated with emotion, including the amygdala, insula, substantia nigra and bed nucleus of the stria terminalis complex. Moreover, trait levels of experiential avoidance were negatively correlated with insula, hippocampal and amygdala activation. These findings suggest knowledge that one can consistently avoid aversive outcomes is not associated with decreased threat-related responses and that individuals with greater experiential avoidance exhibit reduced reactivity to initial threat. Implications for understanding brain mechanisms supporting human avoidance and psychological theories of avoidance are discussed. PMID:24095880

  17. Audit shock avoidance

    SciTech Connect

    Cooper, H.A.

    1994-10-01

    As the number of generating facilities constructed by independent power companies grows in the United States, one undesired by-product will likely be increased scrutiny of the federal income tax treatment of these projects by the Internal Revenue Service (IRS). The IRS has been quite active in recent years auditing electric generating facilities owned by electric utilities, and there is no reason to believe independent power plants will receive any different treatment. In auditing independent power plants, the IRS can be expected to use many of the same arguments and take many of the same positions that it has developed in utility audits.

  18. Chemical avoidance responses of fishes.

    PubMed

    Tierney, Keith B

    2016-05-01

    The hydrosphere is a repository for all of our waste and mistakes, be they sewage, garbage, process-affected waters, runoff, and gases. For fish living in environments receiving undesirable inputs, moving away seems an obvious way to avoid harm. While this should occur, there are numerous examples where it will not. The inability to avoid harmful environments may lead to sensory impairments that in turn limit the ability to avoid other dangers or locate benefits. For avoidance to occur, the danger must first be perceived, which may not happen if the fish is 'blinded' in some capacity. Second, the danger must be recognized for what it is, which may also not happen if the fish is cognitively confused or impaired. Third, it is possible that the fish may not be able to leave the area, or worse, learns to prefer a toxic environment. Concerning generating regulations around avoidance, there are two possibilities: that an avoidance threshold be used to set guidelines for effluent release with the intention of driving fishes away; the second is to set a contaminant concentration that would not affect the avoidance or attraction responses to other cues. With the complexities of the modern world in which we release diverse pollutants, from light to municipal effluents full of 1000s of chemicals, to the diversity present in ecosystems, it is impossible to have avoidance data on every stimulus-species combination. Nevertheless, we may be able to use existing avoidance response data to predict the likelihood of avoidance of untested stimuli. Where we cannot, this review includes a framework that can be used to direct new research. This review is intended to collate existing avoidance response data, provide a framework for making decisions in the absence of data, and suggest studies that would facilitate the prediction of risk to fish health in environments receiving intentional and unintentional human-based chemical inputs.

  19. Chemical avoidance responses of fishes.

    PubMed

    Tierney, Keith B

    2016-05-01

    The hydrosphere is a repository for all of our waste and mistakes, be they sewage, garbage, process-affected waters, runoff, and gases. For fish living in environments receiving undesirable inputs, moving away seems an obvious way to avoid harm. While this should occur, there are numerous examples where it will not. The inability to avoid harmful environments may lead to sensory impairments that in turn limit the ability to avoid other dangers or locate benefits. For avoidance to occur, the danger must first be perceived, which may not happen if the fish is 'blinded' in some capacity. Second, the danger must be recognized for what it is, which may also not happen if the fish is cognitively confused or impaired. Third, it is possible that the fish may not be able to leave the area, or worse, learns to prefer a toxic environment. Concerning generating regulations around avoidance, there are two possibilities: that an avoidance threshold be used to set guidelines for effluent release with the intention of driving fishes away; the second is to set a contaminant concentration that would not affect the avoidance or attraction responses to other cues. With the complexities of the modern world in which we release diverse pollutants, from light to municipal effluents full of 1000s of chemicals, to the diversity present in ecosystems, it is impossible to have avoidance data on every stimulus-species combination. Nevertheless, we may be able to use existing avoidance response data to predict the likelihood of avoidance of untested stimuli. Where we cannot, this review includes a framework that can be used to direct new research. This review is intended to collate existing avoidance response data, provide a framework for making decisions in the absence of data, and suggest studies that would facilitate the prediction of risk to fish health in environments receiving intentional and unintentional human-based chemical inputs. PMID:26970365

  20. Organising European technical documentation to avoid duplication.

    PubMed

    Donawa, Maria

    2006-04-01

    The development of comprehensive accurate and well-organised technical documentation that demonstrates compliance with regulatory requirements is a resource-intensive, but critically important activity for medical device manufacturers. This article discusses guidance documents and method of organising technical documentation that may help avoid costly and time-consuming duplication.

  1. Organising European technical documentation to avoid duplication.

    PubMed

    Donawa, Maria

    2006-04-01

    The development of comprehensive accurate and well-organised technical documentation that demonstrates compliance with regulatory requirements is a resource-intensive, but critically important activity for medical device manufacturers. This article discusses guidance documents and method of organising technical documentation that may help avoid costly and time-consuming duplication. PMID:16736662

  2. Geosynchronous satellite collision avoidance

    NASA Technical Reports Server (NTRS)

    Fraser, W.

    1985-01-01

    The increases in the number of satellite systems, the growing dependency on these systems, and the potentially hazardous conjunctions in space, dictates careful management of satellite positions. The potential for satellite collision increases as more objects are placed in orbit. At geosynchronous altitudes active satellites maintain fixed longitudinal station-keeping control while inactive satellites and debris generally drift around the globe or oscillate about two geopotential stable points. Portions of the total objects in geosynchronous orbit are tracked by ground stations while a significant number of additional pieces of space debris regularly pass through geosynchronous orbit altitudes. The probability of an operational satellite colliding with another satellite or a piece of space debris will increase in the number of space objects, their sizes, and on-orbit lifetimes.

  3. Cigarette tax avoidance and evasion.

    PubMed

    Stehr, Mark

    2005-03-01

    Variation in state cigarette taxes provides incentives for tax avoidance through smuggling, legal border crossing to low tax jurisdictions, or Internet purchasing. When taxes rise, tax paid sales of cigarettes will decline both because consumption will decrease and because tax avoidance will increase. The key innovation of this paper is to compare cigarette sales data to cigarette consumption data from the Behavioral Risk Factor Surveillance System (BRFSS). I show that after subtracting percent changes in consumption, residual percent changes in sales are associated with state cigarette tax changes implying the existence of tax avoidance. I estimate that the tax avoidance response to tax changes is at least twice the consumption response and that tax avoidance accounted for up to 9.6% of sales between 1985 and 2001. Because of the increase in tax avoidance, tax paid sales data understate the level of smoking and overstate the drop in smoking. I also find that the level of legal border crossing was very low relative to other forms of tax avoidance. If states have strong preferences for smoking control, they must pair high cigarette taxes with effective policies to curb smuggling and other forms of tax avoidance or employ alternative policies such as counter-advertising and smoking restrictions. PMID:15721046

  4. Infection-avoidance behaviour in humans and other animals.

    PubMed

    Curtis, Valerie A

    2014-10-01

    Compared with living free, the parasitic way of life has many attractions. Parasites create problems for all animals. Potential hosts can respond by learning to live with parasites (tolerance), actively fighting them (resistance), or they can avoid becoming infected in the first place (avoidance). I propose here a new classification of avoidance behaviour according to the epidemiology of infection risk, where animals must avoid (i) conspecifics, (ii) parasites and their vectors, (iii) parasite-rich environments, and (iv) niche infestation. I further explore how the disgust adaptive system, which coordinates avoidance behaviour, may form a continuum with the immune system through the sharing of signalling pathways, sites of action, and evolutionary history.

  5. Handling data redundancy in helical cone beam reconstruction with a cone-angle-based window function and its asymptotic approximation

    SciTech Connect

    Tang Xiangyang; Hsieh Jiang

    2007-06-15

    A cone-angle-based window function is defined in this manuscript for image reconstruction using helical cone beam filtered backprojection (CB-FBP) algorithms. Rather than defining the window boundaries in a two-dimensional detector acquiring projection data for computed tomographic imaging, the cone-angle-based window function deals with data redundancy by selecting rays with the smallest cone angle relative to the reconstruction plane. To be computationally efficient, an asymptotic approximation of the cone-angle-based window function is also given and analyzed in this paper. The benefit of using such an asymptotic approximation also includes the avoidance of functional discontinuities that cause artifacts in reconstructed tomographic images. The cone-angle-based window function and its asymptotic approximation provide a way, equivalent to the Tam-Danielsson-window, for helical CB-FBP reconstruction algorithms to deal with data redundancy, regardless of where the helical pitch is constant or dynamically variable during a scan. By taking the cone-parallel geometry as an example, a computer simulation study is conducted to evaluate the proposed window function and its asymptotic approximation for helical CB-FBP reconstruction algorithm to handle data redundancy. The computer simulated Forbild head and thorax phantoms are utilized in the performance evaluation, showing that the proposed cone-angle-based window function and its asymptotic approximation can deal with data redundancy very well in cone beam image reconstruction from projection data acquired along helical source trajectories. Moreover, a numerical study carried out in this paper reveals that the proposed cone-angle-based window function is actually equivalent to the Tam-Danielsson-window, and rigorous mathematical proofs are being investigated.

  6. Postcopulatory inbreeding avoidance in guppies.

    PubMed

    Fitzpatrick, J L; Evans, J P

    2014-12-01

    In many species, the negative fitness effects of inbreeding have facilitated the evolution of a wide range of inbreeding avoidance mechanisms. Although avoidance mechanisms operating prior to mating are well documented, evidence for postcopulatory mechanisms of inbreeding avoidance remain scarce. Here, we examine the potential for paternity biases to favour unrelated males when their sperm compete for fertilizations though postcopulatory inbreeding avoidance mechanisms in the guppy, Poecilia reticulata. To test this possibility, we used a series of artificial inseminations to deliver an equal number of sperm from a related (either full sibling or half sibling) and unrelated male to a female while statistically controlling for differences in sperm quality between rival ejaculates. In this way, we were able to focus exclusively on postcopulatory mechanisms of inbreeding avoidance and account for differences in sperm competitiveness between rival males. Under these carefully controlled conditions, we report a significant bias in paternity towards unrelated males, although this effect was only apparent when the related male was a full sibling. We also show that sperm competition generally favours males with highly viable sperm and thus that some variance in sperm competitiveness can be attributed to difference in sperm quality. Our findings for postcopulatory inbreeding avoidance are consistent with prior work on guppies, revealing that sperm competition success declines linearly with the level of relatedness, but also that such effects are only apparent at relatedness levels of full siblings or higher. These findings reveal that postcopulatory processes alone can facilitate inbreeding avoidance.

  7. Postcopulatory inbreeding avoidance in guppies.

    PubMed

    Fitzpatrick, J L; Evans, J P

    2014-12-01

    In many species, the negative fitness effects of inbreeding have facilitated the evolution of a wide range of inbreeding avoidance mechanisms. Although avoidance mechanisms operating prior to mating are well documented, evidence for postcopulatory mechanisms of inbreeding avoidance remain scarce. Here, we examine the potential for paternity biases to favour unrelated males when their sperm compete for fertilizations though postcopulatory inbreeding avoidance mechanisms in the guppy, Poecilia reticulata. To test this possibility, we used a series of artificial inseminations to deliver an equal number of sperm from a related (either full sibling or half sibling) and unrelated male to a female while statistically controlling for differences in sperm quality between rival ejaculates. In this way, we were able to focus exclusively on postcopulatory mechanisms of inbreeding avoidance and account for differences in sperm competitiveness between rival males. Under these carefully controlled conditions, we report a significant bias in paternity towards unrelated males, although this effect was only apparent when the related male was a full sibling. We also show that sperm competition generally favours males with highly viable sperm and thus that some variance in sperm competitiveness can be attributed to difference in sperm quality. Our findings for postcopulatory inbreeding avoidance are consistent with prior work on guppies, revealing that sperm competition success declines linearly with the level of relatedness, but also that such effects are only apparent at relatedness levels of full siblings or higher. These findings reveal that postcopulatory processes alone can facilitate inbreeding avoidance. PMID:25387854

  8. Susceptibility of Redundant Versus Singular Clock Domains Implemented in SRAM-Based FPGA TMR Designs

    NASA Technical Reports Server (NTRS)

    Berg, Melanie D.; LaBel, Kenneth A.; Pellish, Jonathan

    2016-01-01

    We present the challenges that arise when using redundant clock domains due to their clock-skew. Radiation data show that a singular clock domain (DTMR) provides an improved TMR methodology for SRAM-based FPGAs over redundant clocks.

  9. The Birth and Death of Redundancy in Decoherence and Quantum Darwinism

    NASA Astrophysics Data System (ADS)

    Riedel, Charles; Zurek, Wojciech; Zwolak, Michael

    2012-02-01

    Understanding the quantum-classical transition and the identification of a preferred classical domain through quantum Darwinism is based on recognizing high-redundancy states as both ubiquitous and exceptional. They are produced ubiquitously during decoherence, as has been demonstrated by the recent identification of very general conditions under which high-redundancy states develop. They are exceptional in that high-redundancy states occupy a very narrow corner of the global Hilbert space; states selected at random are overwelming likely to exhibit zero redundancy. In this letter, we examine the conditions and time scales for the transition from high-redundancy states to zero-redundancy states in many-body dynamics. We identify sufficient condition for the development of redundancy from product states and show that the destruction of redundancy can be accomplished even with highly constrained interactions.

  10. The Effect of Redundant Cues on Comprehension of Spoken Messages by Aphasic Adults.

    ERIC Educational Resources Information Center

    Venus, Carol A.; Canter, Gerald J.

    1987-01-01

    Aphasic adults (N=16) with severe auditory comprehension impairment were evaluated for comprehension of redundant and nonredundant spoken and/or gestured messages. Results indicated redundancy was not reliably superior to spoken messages alone. (Author/DB)

  11. Vertical jumping and signaled avoidance

    PubMed Central

    Cándido, Antonio; Maldonado, Antonio; Vila, Jaime

    1988-01-01

    This paper reports an experiment intended to demonstrate that the vertical jumping response can be learned using a signaled-avoidance technique. A photoelectric cell system was used to record the response. Twenty female rats, divided equally into two groups, were exposed to intertrial intervals of either 15 or 40 s. Subjects had to achieve three successive criteria of acquisition: 3, 5, and 10 consecutive avoidance responses. Results showed that both groups learned the avoidance response, requiring increasingly larger numbers of trials as the acquisition criteria increased. No significant effect of intertrial interval was observed. PMID:16812559

  12. Continuous Aerobic Training in Individualized Intensity Avoids Spontaneous Physical Activity Decline and Improves MCT1 Expression in Oxidative Muscle of Swimming Rats

    PubMed Central

    Scariot, Pedro P. M.; Manchado-Gobatto, Fúlvia de Barros; Torsoni, Adriana S.; dos Reis, Ivan G. M.; Beck, Wladimir R.; Gobatto, Claudio A.

    2016-01-01

    Although aerobic training has been shown to affect the lactate transport of skeletal muscle, there is no information concerning the effect of continuous aerobic training on spontaneous physical activity (SPA). Because every movement in daily life (i.e., SPA) is generated by skeletal muscle, we think that it is possible that an improvement of SPA could affect the physiological properties of muscle with regard to lactate transport. The aim of this study was to evaluate the effect of 12 weeks of continuous aerobic training in individualized intensity on SPA of rats and their gene expressions of monocarboxylate transporters (MCT) 1 and 4 in soleus (oxidative) and white gastrocnemius (glycolytic) muscles. We also analyzed the effect of continuous aerobic training on aerobic and anaerobic parameters using the lactate minimum test (LMT). Sixty-day-old rats were randomly divided into three groups: a baseline group in which rats were evaluated prior to initiation of the study; a control group (Co) in which rats were kept without any treatment during 12 weeks; and a chronic exercise group (Tr) in which rats swam for 40 min/day, 5 days/week at 80% of anaerobic threshold during 12 weeks. After the experimental period, SPA of rats was measured using a gravimetric method. Rats had their expression of MCTs determined by RT-PCR analysis. In essence, aerobic training is effective in maintaining SPA, but did not prevent the decline of aerobic capacity and anaerobic performance, leading us to propose that the decline of SPA is not fully attributed to a deterioration of physical properties. Changes in SPA were concomitant with changes in MCT1 expression in the soleus muscle of trained rats, suggestive of an additional adaptive response toward increased lactate clearance. This result is in line with our observation showing a better equilibrium on lactate production-remotion during the continuous exercise (LMT). We propose an approach to combat the decline of SPA of rats in their home

  13. Continuous Aerobic Training in Individualized Intensity Avoids Spontaneous Physical Activity Decline and Improves MCT1 Expression in Oxidative Muscle of Swimming Rats.

    PubMed

    Scariot, Pedro P M; Manchado-Gobatto, Fúlvia de Barros; Torsoni, Adriana S; Dos Reis, Ivan G M; Beck, Wladimir R; Gobatto, Claudio A

    2016-01-01

    Although aerobic training has been shown to affect the lactate transport of skeletal muscle, there is no information concerning the effect of continuous aerobic training on spontaneous physical activity (SPA). Because every movement in daily life (i.e., SPA) is generated by skeletal muscle, we think that it is possible that an improvement of SPA could affect the physiological properties of muscle with regard to lactate transport. The aim of this study was to evaluate the effect of 12 weeks of continuous aerobic training in individualized intensity on SPA of rats and their gene expressions of monocarboxylate transporters (MCT) 1 and 4 in soleus (oxidative) and white gastrocnemius (glycolytic) muscles. We also analyzed the effect of continuous aerobic training on aerobic and anaerobic parameters using the lactate minimum test (LMT). Sixty-day-old rats were randomly divided into three groups: a baseline group in which rats were evaluated prior to initiation of the study; a control group (Co) in which rats were kept without any treatment during 12 weeks; and a chronic exercise group (Tr) in which rats swam for 40 min/day, 5 days/week at 80% of anaerobic threshold during 12 weeks. After the experimental period, SPA of rats was measured using a gravimetric method. Rats had their expression of MCTs determined by RT-PCR analysis. In essence, aerobic training is effective in maintaining SPA, but did not prevent the decline of aerobic capacity and anaerobic performance, leading us to propose that the decline of SPA is not fully attributed to a deterioration of physical properties. Changes in SPA were concomitant with changes in MCT1 expression in the soleus muscle of trained rats, suggestive of an additional adaptive response toward increased lactate clearance. This result is in line with our observation showing a better equilibrium on lactate production-remotion during the continuous exercise (LMT). We propose an approach to combat the decline of SPA of rats in their home

  14. Genetic Redundancies Enhance Information Transfer in Noisy Regulatory Circuits

    PubMed Central

    Rodrigo, Guillermo; Poyatos, Juan F.

    2016-01-01

    Cellular decision making is based on regulatory circuits that associate signal thresholds to specific physiological actions. This transmission of information is subjected to molecular noise what can decrease its fidelity. Here, we show instead how such intrinsic noise enhances information transfer in the presence of multiple circuit copies. The result is due to the contribution of noise to the generation of autonomous responses by each copy, which are altogether associated with a common decision. Moreover, factors that correlate the responses of the redundant units (extrinsic noise or regulatory cross-talk) contribute to reduce fidelity, while those that further uncouple them (heterogeneity within the copies) can lead to stronger information gain. Overall, our study emphasizes how the interplay of signal thresholding, redundancy, and noise influences the accuracy of cellular decision making. Understanding this interplay provides a basis to explain collective cell signaling mechanisms, and to engineer robust decisions with noisy genetic circuits. PMID:27741249

  15. The dynamics of neuronal redundancy in decision making

    NASA Astrophysics Data System (ADS)

    Daniels, Bryan; Flack, Jessica; Krakauer, David

    We propose two temporal phases of collective computation in a visual motion direction discrimination task by analyzing recordings from 169 neural channels in the prefrontal cortex of macaque monkeys. Phase I is a distributed phase in which uncertainty is substantially reduced by pooling information from many cells. Phase II is a redundant phase in which numerous single cells contain all the information present at the population level in Phase I. A dynamic distributed model connects low redundancy to a slow timescale of information aggregation, and provides a common explanation for both behaviors that differs only in the degree of recurrent excitation. We attribute the slow timescale of information accumulation to critical slowing down near the transition to a memory-carrying collective state. We suggest that this dynamic of slow distributed accumulation followed by fast collective propagation is a generic feature of robust collective computing systems related to consensus formation.

  16. A bat algorithm for the redundancy allocation problem

    NASA Astrophysics Data System (ADS)

    Talafuse, T. P.; Pohl, E. A.

    2016-05-01

    This article uses a recently developed bat algorithm (BA) meta-heuristic optimization method to solve the reliability redundancy allocation problem (RAP). The RAP is a well-known NP-hard problem which has been the subject of much prior work, generally of a restricted form where each component must consist of identical components in parallel to make computations tractable. Meta-heuristic methods overcome this limitation and allow for larger instances to be solved for a more general case where different components can be placed in parallel. The BA has not yet been used in reliability design, as it was a method initially designed for continuous problems. A BA is devised and tested on a well-known suite of problems from the literature. It is shown that the BA is competitive with the best known heuristics for redundancy allocation.

  17. Information theory and artificial grammar learning: inferring grammaticality from redundancy.

    PubMed

    Jamieson, Randall K; Nevzorova, Uliana; Lee, Graham; Mewhort, D J K

    2016-03-01

    In artificial grammar learning experiments, participants study strings of letters constructed using a grammar and then sort novel grammatical test exemplars from novel ungrammatical ones. The ability to distinguish grammatical from ungrammatical strings is often taken as evidence that the participants have induced the rules of the grammar. We show that judgements of grammaticality are predicted by the local redundancy of the test strings, not by grammaticality itself. The prediction holds in a transfer test in which test strings involve different letters than the training strings. Local redundancy is usually confounded with grammaticality in stimuli widely used in the literature. The confounding explains why the ability to distinguish grammatical from ungrammatical strings has popularized the idea that participants have induced the rules of the grammar, when they have not. We discuss the judgement of grammaticality task in terms of attribute substitution and pattern goodness. When asked to judge grammaticality (an inaccessible attribute), participants answer an easier question about pattern goodness (an accessible attribute).

  18. Preliminary study of a serial-parallel redundant manipulator

    NASA Technical Reports Server (NTRS)

    Hayward, Vincent; Kurtz, Ronald

    1989-01-01

    The manipulator design discussed here results from the examination of some of the reasons why redundancy is necessary in general purpose manipulation systems. A spherical joint design actuated in-parallel, having the many advantages of parallel actuation, is described. In addition, the benefits of using redundant actuators are discussed and illustrated in the design by the elimination of loci of singularities from the usable workspace with the addition of only one actuator. Finally, what is known by the authors about space robotics requirements is summarized and the relevance of the proposed design matched against these requirements. The design problems outlined here are viewed as much from the mechanical engineering aspect as from concerns arising from the control and the programming of manipulators.

  19. Converging evidence of social avoidant behavior in schizophrenia from two approach-avoidance tasks.

    PubMed

    de la Asuncion, Javier; Docx, Lise; Sabbe, Bernard; Morrens, Manuel; de Bruijn, Ellen R A

    2015-10-01

    Many people with schizophrenia suffer from social impairments characterized by active social avoidance, which is related to social phobia common in schizophrenia, while motivational impairments can also result in passive social withdrawal. Although social avoidance is frequently reported in this population, this is the first study to directly compare approach-avoidance tendencies in schizophrenia patients (N = 37) and healthy controls (N = 29). Participants performed two tasks: a computerized approach-avoidance task (AAT) to assess response tendencies toward images of happy and angry faces with direct or averted gaze and a one-to-one personal space test (PST) to gauge more naturalistic approach-avoidance behaviors toward a real person bearing a neutral expression. The AAT results showed that both groups showed faster avoidance responses to angry faces and faster approach responses to happy faces with a direct gaze. Happy faces with averted gaze, however, resulted in faster avoidance responses in the patient group only. On the PST, the patients approached the experimenter less than healthy controls did. This measure of interpersonal distance was positively related to positive symptom severity. Delusions of reference and increased sensitivity to social rejection may explain the patients' avoidance tendencies in response to pictures of happy faces with averted gaze and in the presence of an actual person. The current findings demonstrate the importance of others adopting positive and unambiguous attitudes when interacting with schizophrenia patients to minimize behavioral avoidance patterns, which is particularly relevant for relatives and clinicians whose interactions with the patients are crucial to facilitating treatment and promoting healthy social relationships.

  20. Converging evidence of social avoidant behavior in schizophrenia from two approach-avoidance tasks.

    PubMed

    de la Asuncion, Javier; Docx, Lise; Sabbe, Bernard; Morrens, Manuel; de Bruijn, Ellen R A

    2015-10-01

    Many people with schizophrenia suffer from social impairments characterized by active social avoidance, which is related to social phobia common in schizophrenia, while motivational impairments can also result in passive social withdrawal. Although social avoidance is frequently reported in this population, this is the first study to directly compare approach-avoidance tendencies in schizophrenia patients (N = 37) and healthy controls (N = 29). Participants performed two tasks: a computerized approach-avoidance task (AAT) to assess response tendencies toward images of happy and angry faces with direct or averted gaze and a one-to-one personal space test (PST) to gauge more naturalistic approach-avoidance behaviors toward a real person bearing a neutral expression. The AAT results showed that both groups showed faster avoidance responses to angry faces and faster approach responses to happy faces with a direct gaze. Happy faces with averted gaze, however, resulted in faster avoidance responses in the patient group only. On the PST, the patients approached the experimenter less than healthy controls did. This measure of interpersonal distance was positively related to positive symptom severity. Delusions of reference and increased sensitivity to social rejection may explain the patients' avoidance tendencies in response to pictures of happy faces with averted gaze and in the presence of an actual person. The current findings demonstrate the importance of others adopting positive and unambiguous attitudes when interacting with schizophrenia patients to minimize behavioral avoidance patterns, which is particularly relevant for relatives and clinicians whose interactions with the patients are crucial to facilitating treatment and promoting healthy social relationships. PMID:26343605

  1. Lockheed L-1101 avionic flight control redundant systems

    NASA Technical Reports Server (NTRS)

    Throndsen, E. O.

    1976-01-01

    The Lockheed L-1011 automatic flight control systems - yaw stability augmentation and automatic landing - are described in terms of their redundancies. The reliability objectives for these systems are discussed and related to in-service experience. In general, the availability of the stability augmentation system is higher than the original design requirement, but is commensurate with early estimates. The in-service experience with automatic landing is not sufficient to provide verification of Category 3 automatic landing system estimated availability.

  2. Improved actions, redundant operators and scaling in lattice SU(3)

    NASA Astrophysics Data System (ADS)

    Patel, Apoorva; Gupta, Rajan

    1987-01-01

    Schwinger-Dyson equations are used to systematically calculate redundant operators in lattice QCD and their role in perturbatively improved actions is analyzed. The criteria for improved actions in Monte Carlo simulations are discussed and their usefulness also. In particular the renormalized trajectory is estimated for the b = sqrt(3) renormalization group transformation in a four-parameter space and its scaling behavior is studied for future use in spectrum calculations. J. Robert Oppenheimer Fellow.

  3. A redundant regulator control with low standby losses

    NASA Technical Reports Server (NTRS)

    Andryczyk, R. W.; Peck, S. R.

    1980-01-01

    Shunt regulator circuit for outer-planet-spacecraft radiosotope thermoelectric generator minimizes power-conditioning losses. Unit consists of bank of duplicate regulator control amplifiers and their associated shunt transistors connecter across power supply line. Its high-gain circuitry arranged in redundant configuration in very reliable and is characterized by low standby loss. Circuit can be used on other power-supply applications where size, weight, and reliability are important.

  4. General test plan redundant sensor strapdown IMU evaluation program

    NASA Technical Reports Server (NTRS)

    Hartwell, T.; Irwin, H. A.; Miyatake, Y.; Wedekind, D. E.

    1971-01-01

    The general test plan for a redundant sensor strapdown inertial measuring unit evaluation program is presented. The inertial unit contains six gyros and three orthogonal accelerometers. The software incorporates failure detection and correction logic and a land vehicle navigation program. The principal objective of the test is a demonstration of the practicability, reliability, and performance of the inertial measuring unit with failure detection and correction in operational environments.

  5. Optimal Management of Redundant Control Authority for Fault Tolerance

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva; Ju, Jianhong

    2000-01-01

    This paper is intended to demonstrate the feasibility of a solution to a fault tolerant control problem. It explains, through a numerical example, the design and the operation of a novel scheme for fault tolerant control. The fundamental principle of the scheme was formalized in [5] based on the notion of normalized nonspecificity. The novelty lies with the use of a reliability criterion for redundancy management, and therefore leads to a high overall system reliability.

  6. Low redundancy in seed dispersal within an island frugivore community

    PubMed Central

    McConkey, Kim R.; Drake, Donald R.

    2015-01-01

    The low species diversity that often characterizes island ecosystems could result in low functional redundancy within communities. Flying foxes (large fruit bats) are important seed dispersers of large-seeded species, but their redundancy within island communities has never been explicitly tested. In a Pacific archipelago, we found that flying foxes were the sole effective disperser of 57 % of the plant species whose fruits they consume. They were essential for the dispersal of these species either because they handled >90 % of consumed fruit, or were the only animal depositing seeds away from the parent canopy, or both. Flying foxes were especially important for larger-seeded fruit (>13 mm wide), with 76 % of consumed species dependent on them for dispersal, compared with 31 % of small-seeded species. As flying foxes decrease in abundance, they cease to function as dispersers long before they become rare. We compared the seed dispersal effectiveness (measured as the proportion of diaspores dispersed beyond parent crowns) of all frugivores for four plant species in sites where flying foxes were, and were not, functionally extinct. At both low and high abundance, flying foxes consumed most available fruit of these species, but the proportion of handled diaspores dispersed away from parent crowns (quality) was significantly reduced at low abundance. Since alternative consumers (birds, rodents and land crabs) were unable to compensate as dispersers when flying foxes were functionally extinct, we conclude that there is almost no redundancy in the seed dispersal function of flying foxes in this island system, and potentially on other islands where they occur. Given that oceanic island communities are often simpler than continental communities, evaluating the extent of redundancy across different ecological functions on islands is extremely important. PMID:26194167

  7. Redundant sensorized arm+hand system for space telerobotized manipulation

    NASA Technical Reports Server (NTRS)

    Rovetta, Alberto; Cavestro, Paolo

    1989-01-01

    An integrated system, composed of an arm, a wrist, and a mechanical multifingered hand is treated. The hand is on development for possible application in telemanipulation, and is realized in separate parts. The redundancy of the degrees of freedom of the system, the sensors, the application of logical rules, and the supervision of teleoperators may be applied in order to have an optimum of reliability of the system in space telemanipulations.

  8. Superlinearly scalable noise robustness of redundant coupled dynamical systems.

    PubMed

    Kohar, Vivek; Kia, Behnam; Lindner, John F; Ditto, William L

    2016-03-01

    We illustrate through theory and numerical simulations that redundant coupled dynamical systems can be extremely robust against local noise in comparison to uncoupled dynamical systems evolving in the same noisy environment. Previous studies have shown that the noise robustness of redundant coupled dynamical systems is linearly scalable and deviations due to noise can be minimized by increasing the number of coupled units. Here, we demonstrate that the noise robustness can actually be scaled superlinearly if some conditions are met and very high noise robustness can be realized with very few coupled units. We discuss these conditions and show that this superlinear scalability depends on the nonlinearity of the individual dynamical units. The phenomenon is demonstrated in discrete as well as continuous dynamical systems. This superlinear scalability not only provides us an opportunity to exploit the nonlinearity of physical systems without being bogged down by noise but may also help us in understanding the functional role of coupled redundancy found in many biological systems. Moreover, engineers can exploit superlinear noise suppression by starting a coupled system near (not necessarily at) the appropriate initial condition.

  9. Superlinearly scalable noise robustness of redundant coupled dynamical systems

    NASA Astrophysics Data System (ADS)

    Kohar, Vivek; Kia, Behnam; Lindner, John F.; Ditto, William L.

    2016-03-01

    We illustrate through theory and numerical simulations that redundant coupled dynamical systems can be extremely robust against local noise in comparison to uncoupled dynamical systems evolving in the same noisy environment. Previous studies have shown that the noise robustness of redundant coupled dynamical systems is linearly scalable and deviations due to noise can be minimized by increasing the number of coupled units. Here, we demonstrate that the noise robustness can actually be scaled superlinearly if some conditions are met and very high noise robustness can be realized with very few coupled units. We discuss these conditions and show that this superlinear scalability depends on the nonlinearity of the individual dynamical units. The phenomenon is demonstrated in discrete as well as continuous dynamical systems. This superlinear scalability not only provides us an opportunity to exploit the nonlinearity of physical systems without being bogged down by noise but may also help us in understanding the functional role of coupled redundancy found in many biological systems. Moreover, engineers can exploit superlinear noise suppression by starting a coupled system near (not necessarily at) the appropriate initial condition.

  10. Verbal redundancy aids memory for filmed entertainment dialogue.

    PubMed

    Hinkin, Michael P; Harris, Richard J; Miranda, Andrew T

    2014-01-01

    Three studies investigated the effects of presentation modality and redundancy of verbal content on recognition memory for entertainment film dialogue. U.S. participants watched two brief movie clips and afterward answered multiple-choice questions about information from the dialogue. Experiment 1 compared recognition memory for spoken dialogue in the native language (English) with subtitles in English, French, or no subtitles. Experiment 2 compared memory for material in English subtitles with spoken dialogue in English, French, or no sound. Experiment 3 examined three control conditions with no spoken or captioned material in the native language. All participants watched the same video clips and answered the same questions. Performance was consistently good whenever English dialogue appeared in either the subtitles or sound, and best of all when it appeared in both, supporting the facilitation of verbal redundancy. Performance was also better when English was only in the subtitles than when it was only spoken. Unexpectedly, sound or subtitles in an unfamiliar language (French) modestly improved performance, as long as there was also a familiar channel. Results extend multimedia research on verbal redundancy for expository material to verbal information in entertainment media.

  11. NK cell development and function--plasticity and redundancy unleashed.

    PubMed

    Cichocki, Frank; Sitnicka, Ewa; Bryceson, Yenan T

    2014-04-01

    Bone marrow-derived natural killer (NK) cells constitute the major subset of cytotoxic lymphocytes in peripheral blood. They provide innate defense against intracellular infection or malignancy and contribute to immune homeostasis. Large numbers of NK cells are also present in tissues, including the liver and uterus, where they can mediate immunosurveillance but also play important roles in tissue remodeling and vascularization. Here, we review the pathways involved in NK cell lineage commitment and differentiation, discussing relationships to other lymphocyte populations and highlighting genetic determinants. Characterizing NK cells from distinct tissues and during infections have revealed subset specializations, reflecting inherent cellular plasticity. In this context, we discuss how different environmental and inflammatory stimuli may shape NK cells. Particular emphasis is placed on genes identified as being critical for NK cell development, differentiation, and function from studies of model organisms or associations with disease. Such studies are also revealing important cellular redundancies. Here, we provide a view of the genetic framework constraining NK cell development and function, pinpointing molecules required for these processes but also underscoring plasticity and redundancy that may underlie robust immunological function. With this view, built in redundancy may highlight the importance of NK cells to immunity.

  12. Redundancy analysis of raw Geiger-mode laser radar data

    NASA Astrophysics Data System (ADS)

    Lopez, Norman A.; Kamerman, Gary W.

    2010-04-01

    In the past decade arrays of Geiger-mode Avalanche Photodiode (GmAPD) detectors have increased in size from 4×4 to 128×32, resulting in significant increases in data rates. If not handled appropriately, data collected with larger arrays and higher laser pulse repetition frequencies could potentially stress existing data dissemination and storage infrastructures. Data compression techniques that reduce storage requirements by taking advantage of data redundancies could be used to mitigate this problem. In this paper we present an analysis of the coding redundancy that exists in raw data captured with three dimensional imaging laser radar systems that employ arrays of Geiger-mode Avalanche Photodiode (GmAPD) detectors. The data we analyzed was collected in three different scanning modes, namely: mapping-mode, target-mode and stare-mode. We found that there is a significant amount of coding redundancy in raw GmAPD data which can be used to minimize storage sizes. We demonstrate that a trivial and simple approach reduces data for some scan patterns. This work represents a first step towards developing robust compression algorithms for raw GmAPD data. We present considerations for future work.

  13. Effects of Response Task and Accessory Stimuli on Redundancy Gain: Tests of the Hemispheric Coactivation Model

    ERIC Educational Resources Information Center

    Miller, Jeff; Van Nes, Fenna

    2007-01-01

    Two experiments tested predictions of the hemispheric coactivation model for redundancy gain (J. O. Miller, 2004). Simple reaction time was measured in divided attention tasks with visual stimuli presented to the left or right of fixation or redundantly to both sides. Experiment 1 tested the prediction that redundancy gain--the decrease in…

  14. Fusion Prevents the Redundant Signals Effect: Evidence from Stereoscopically Presented Stimuli

    ERIC Educational Resources Information Center

    Schroter, Hannes; Fiedler, Anja; Miller, Jeff; Ulrich, Rolf

    2011-01-01

    In a simple reaction time (RT) experiment, visual stimuli were stereoscopically presented either to one eye (single stimulation) or to both eyes (redundant stimulation), with brightness matched for single and redundant stimulations. Redundant stimulation resulted in two separate percepts when noncorresponding retinal areas were stimulated, whereas…

  15. Vision-based obstacle avoidance

    DOEpatents

    Galbraith, John

    2006-07-18

    A method for allowing a robot to avoid objects along a programmed path: first, a field of view for an electronic imager of the robot is established along a path where the electronic imager obtains the object location information within the field of view; second, a population coded control signal is then derived from the object location information and is transmitted to the robot; finally, the robot then responds to the control signal and avoids the detected object.

  16. Predator Avoidance in Extremophile Fish

    PubMed Central

    Bierbach, David; Schulte, Matthias; Herrmann, Nina; Zimmer, Claudia; Arias-Rodriguez, Lenin; Indy, Jeane Rimber; Riesch, Rüdiger; Plath, Martin

    2013-01-01

    Extreme habitats are often characterized by reduced predation pressures, thus representing refuges for the inhabiting species. The present study was designed to investigate predator avoidance of extremophile populations of Poecilia mexicana and P. sulphuraria that either live in hydrogen sulfide-rich (sulfidic) springs or cave habitats, both of which are known to have impoverished piscine predator regimes. Focal fishes that inhabited sulfidic springs showed slightly weaker avoidance reactions when presented with several naturally occurring predatory cichlids, but strongest differences to populations from non-sulfidic habitats were found in a decreased shoaling tendency with non-predatory swordtail (Xiphophorus hellerii) females. When comparing avoidance reactions between P. mexicana from a sulfidic cave (Cueva del Azufre) and the adjacent sulfidic surface creek (El Azufre), we found only slight differences in predator avoidance, but surface fish reacted much more strongly to the non-predatory cichlid Vieja bifasciata. Our third experiment was designed to disentangle learned from innate effects of predator recognition. We compared laboratory-reared (i.e., predator-naïve) and wild-caught (i.e., predator-experienced) individuals of P. mexicana from a non-sulfidic river and found no differences in their reaction towards the presented predators. Overall, our results indicate (1) that predator avoidance is still functional in extremophile Poecilia spp. and (2) that predator recognition and avoidance reactions have a strong genetic basis. PMID:25371337

  17. Predator avoidance in extremophile fish.

    PubMed

    Bierbach, David; Schulte, Matthias; Herrmann, Nina; Zimmer, Claudia; Arias-Rodriguez, Lenin; Indy, Jeane Rimber; Riesch, Rüdiger; Plath, Martin

    2013-01-01

    Extreme habitats are often characterized by reduced predation pressures, thus representing refuges for the inhabiting species. The present study was designed to investigate predator avoidance of extremophile populations of Poecilia mexicana and P. sulphuraria that either live in hydrogen sulfide-rich (sulfidic) springs or cave habitats, both of which are known to have impoverished piscine predator regimes. Focal fishes that inhabited sulfidic springs showed slightly weaker avoidance reactions when presented with several naturally occurring predatory cichlids, but strongest differences to populations from non-sulfidic habitats were found in a decreased shoaling tendency with non-predatory swordtail (Xiphophorus hellerii) females. When comparing avoidance reactions between P. mexicana from a sulfidic cave (Cueva del Azufre) and the adjacent sulfidic surface creek (El Azufre), we found only slight differences in predator avoidance, but surface fish reacted much more strongly to the non-predatory cichlid Vieja bifasciata. Our third experiment was designed to disentangle learned from innate effects of predator recognition. We compared laboratory-reared (i.e., predator-naïve) and wild-caught (i.e., predator-experienced) individuals of P. mexicana from a non-sulfidic river and found no differences in their reaction towards the presented predators. Overall, our results indicate (1) that predator avoidance is still functional in extremophile Poecilia spp. and (2) that predator recognition and avoidance reactions have a strong genetic basis.

  18. Neural systems underlying approach and avoidance in anxiety disorders.

    PubMed

    Aupperle, Robin L; Paulus, Martin P

    2010-01-01

    Approach-avoidance conflict is an important psychological concept that has been used extensively to better understand cognition and emotion. This review focuses on neural systems involved in approach, avoidance, and conflict decision making, and how these systems overlap with implicated neural substrates of anxiety disorders. In particular, the role of amygdala, insula, ventral striatal, and prefrontal regions are discussed with respect to approach and avoidance behaviors. Three specific hypotheses underlying the dysfunction in anxiety disorders are proposed, including: (i) over-representation of avoidance valuation related to limbic overactivation; (ii) under- or over-representation of approach valuation related to attenuated or exaggerated striatal activation respectively; and (iii) insufficient integration and arbitration of approach and avoidance valuations related to attenuated orbitofrontal cortex activation. These dysfunctions can be examined experimentally using versions of existing decision-making paradigms, but may also require new translational and innovative approaches to probe approach-avoidance conflict and related neural systems in anxiety disorders. PMID:21319496

  19. Neural systems underlying approach and avoidance in anxiety disorders

    PubMed Central

    Robin L., Aupperle; Martin, P. Paulus

    2010-01-01

    Approach-avoidance conflict is an important psychological concept that has been used extensively to better understand cognition and emotion. This review focuses on neural systems involved in approach, avoidance, and conflict decision making, and how these systems overlap with implicated neural substrates of anxiety disorders. In particular, the role of amygdala, insula, ventral striatal, and prefrontal regions are discussed with respect to approach and avoidance behaviors. Three specific hypotheses underlying the dysfunction in anxiety disorders are proposed, including: (i) over-representation of avoidance valuation related to limbic overactivation; (ii) under- or over-representation of approach valuation related to attenuated or exaggerated striatal activation respectively; and (iii) insufficient integration and arbitration of approach and avoidance valuations related to attenuated orbitofrontal cortex activation. These dysfunctions can be examined experimentally using versions of existing decision-making paradigms, but may also require new translational and innovative approaches to probe approach-avoidance conflict and related neural systems in anxiety disorders. PMID:21319496

  20. Neural substrates of approach-avoidance conflict decision-making.

    PubMed

    Aupperle, Robin L; Melrose, Andrew J; Francisco, Alex; Paulus, Martin P; Stein, Murray B

    2015-02-01

    Animal approach-avoidance conflict paradigms have been used extensively to operationalize anxiety, quantify the effects of anxiolytic agents, and probe the neural basis of fear and anxiety. Results from human neuroimaging studies support that a frontal-striatal-amygdala neural circuitry is important for approach-avoidance learning. However, the neural basis of decision-making is much less clear in this context. Thus, we combined a recently developed human approach-avoidance paradigm with functional magnetic resonance imaging (fMRI) to identify neural substrates underlying approach-avoidance conflict decision-making. Fifteen healthy adults completed the approach-avoidance conflict (AAC) paradigm during fMRI. Analyses of variance were used to compare conflict to nonconflict (avoid-threat and approach-reward) conditions and to compare level of reward points offered during the decision phase. Trial-by-trial amplitude modulation analyses were used to delineate brain areas underlying decision-making in the context of approach/avoidance behavior. Conflict trials as compared to the nonconflict trials elicited greater activation within bilateral anterior cingulate cortex, anterior insula, and caudate, as well as right dorsolateral prefrontal cortex (PFC). Right caudate and lateral PFC activation was modulated by level of reward offered. Individuals who showed greater caudate activation exhibited less approach behavior. On a trial-by-trial basis, greater right lateral PFC activation related to less approach behavior. Taken together, results suggest that the degree of activation within prefrontal-striatal-insula circuitry determines the degree of approach versus avoidance decision-making. Moreover, the degree of caudate and lateral PFC activation related to individual differences in approach-avoidance decision-making. Therefore, the approach-avoidance conflict paradigm is ideally suited to probe anxiety-related processing differences during approach-avoidance decision

  1. Identification of redundant and synergetic circuits in triplets of electrophysiological data

    NASA Astrophysics Data System (ADS)

    Erramuzpe, Asier; Ortega, Guillermo J.; Pastor, Jesus; de Sola, Rafael G.; Marinazzo, Daniele; Stramaglia, Sebastiano; Cortes, Jesus M.

    2015-12-01

    Objective. Neural systems are comprised of interacting units, and relevant information regarding their function or malfunction can be inferred by analyzing the statistical dependencies between the activity of each unit. While correlations and mutual information are commonly used to characterize these dependencies, our objective here is to extend interactions to triplets of variables to better detect and characterize dynamic information transfer. Approach. Our approach relies on the measure of interaction information (II). The sign of II provides information as to the extent to which the interaction of variables in triplets is redundant (R) or synergetic (S). Three variables are said to be redundant when a third variable, say Z, added to a pair of variables (X, Y), diminishes the information shared between X and Y. Similarly, the interaction in the triplet is said to be synergetic when conditioning on Z enhances the information shared between X and Y with respect to the unconditioned state. Here, based on this approach, we calculated the R and S status for triplets of electrophysiological data recorded from drug-resistant patients with mesial temporal lobe epilepsy in order to study the spatial organization and dynamics of R and S close to the epileptogenic zone (the area responsible for seizure propagation). Main results. In terms of spatial organization, our results show that R matched the epileptogenic zone while S was distributed more in the surrounding area. In relation to dynamics, R made the largest contribution to high frequency bands (14-100 Hz), while S was expressed more strongly at lower frequencies (1-7 Hz). Thus, applying II to such clinical data reveals new aspects of epileptogenic structure in terms of the nature (redundancy versus synergy) and dynamics (fast versus slow rhythms) of the interactions. Significance. We expect this methodology, robust and simple, can reveal new aspects beyond pair-interactions in networks of interacting units in other

  2. Dynamic control of gene regulatory logic by seemingly redundant transcription factors

    PubMed Central

    AkhavanAghdam, Zohreh; Sinha, Joydeb; Tabbaa, Omar P; Hao, Nan

    2016-01-01

    Many transcription factors co-express with their homologs to regulate identical target genes, however the advantages of such redundancies remain elusive. Using single-cell imaging and microfluidics, we study the yeast general stress response transcription factor Msn2 and its seemingly redundant homolog Msn4. We find that gene regulation by these two factors is analogous to logic gate systems. Target genes with fast activation kinetics can be fully induced by either factor, behaving as an 'OR' gate. In contrast, target genes with slow activation kinetics behave as an 'AND' gate, requiring distinct contributions from both factors, upon transient stimulation. Furthermore, such genes become an 'OR' gate when the input duration is prolonged, suggesting that the logic gate scheme is not static but rather dependent on the input dynamics. Therefore, Msn2 and Msn4 enable a time-based mode of combinatorial gene regulation that might be applicable to homologous transcription factors in other organisms. DOI: http://dx.doi.org/10.7554/eLife.18458.001 PMID:27690227

  3. Automatic Collision Avoidance Technology (ACAT)

    NASA Technical Reports Server (NTRS)

    Swihart, Donald E.; Skoog, Mark A.

    2007-01-01

    This document represents two views of the Automatic Collision Avoidance Technology (ACAT). One viewgraph presentation reviews the development and system design of Automatic Collision Avoidance Technology (ACAT). Two types of ACAT exist: Automatic Ground Collision Avoidance (AGCAS) and Automatic Air Collision Avoidance (AACAS). The AGCAS Uses Digital Terrain Elevation Data (DTED) for mapping functions, and uses Navigation data to place aircraft on map. It then scans DTED in front of and around aircraft and uses future aircraft trajectory (5g) to provide automatic flyup maneuver when required. The AACAS uses data link to determine position and closing rate. It contains several canned maneuvers to avoid collision. Automatic maneuvers can occur at last instant and both aircraft maneuver when using data link. The system can use sensor in place of data link. The second viewgraph presentation reviews the development of a flight test and an evaluation of the test. A review of the operation and comparison of the AGCAS and a pilot's performance are given. The same review is given for the AACAS is given.

  4. Quantum Darwinism: Entanglement, branches, and the emergent classicality of redundantly stored quantum information

    NASA Astrophysics Data System (ADS)

    Blume-Kohout, Robin; Zurek, Wojciech H.

    2006-06-01

    We lay a comprehensive foundation for the study of redundant information storage in decoherence processes. Redundancy has been proposed as a prerequisite for objectivity, the defining property of classical objects. We consider two ensembles of states for a model universe consisting of one system and many environments: the first consisting of arbitrary states, and the second consisting of “singly branching” states consistent with a simple decoherence model. Typical states from the random ensemble do not store information about the system redundantly, but information stored in branching states has a redundancy proportional to the environment’s size. We compute the specific redundancy for a wide range of model universes, and fit the results to a simple first-principles theory. Our results show that the presence of redundancy divides information about the system into three parts: classical (redundant); purely quantum; and the borderline, undifferentiated or “nonredundant,” information.

  5. Motive to Avoid Success, Locus of Control, and Reinforcement Avoidance.

    ERIC Educational Resources Information Center

    Katovsky, Walter

    Subjects were four groups of 12 college women, high or low in motive to avoid success (MAS) and locus of control (LC), were reinforced for response A on a fixed partial reinforcement schedule on three concept learning tasks, one task consisting of combined reward and punishment, another of reward only, and one of punishment only. Response B was…

  6. Food Avoidance Diets for Dermatitis.

    PubMed

    Scott, Jeffrey F; Hammond, Margaret I; Nedorost, Susan T

    2015-10-01

    Food allergy is relatively common in both children and adults, and its prevalence is increasing. Early exposure of food allergens onto skin with an impaired epidermal barrier predisposes to sensitization and prevents the development of oral tolerance. While immediate-type food allergies are well described, less is known about delayed-type food allergies manifesting as dermatitis. This is due, in part, to limitations with current diagnostic testing for delayed-type food allergy, including atopy patch testing. We conducted a systematic review of food avoidance diets in delayed-type food allergies manifesting as dermatitis. While beneficial in some clinical circumstances, avoidance diets should be used with caution in infants and children, as growth impairment and developmental delay may result. Ultimately, dermatitis is highly multifactorial and avoidance diets may not improve symptoms of delayed-type food allergy until combined with other targeted therapies, including restoring balance in the skin microbiome and re-establishing proper skin barrier function.

  7. A problem of collision avoidance

    NASA Technical Reports Server (NTRS)

    Vincent, T. L.; Cliff, E. M.; Grantham, W. J.; Peng, W. Y.

    1972-01-01

    Collision avoidance between two vehicles of constant speed with limited turning radii, moving in a horizontal plane is investigated. Collision avoidance is viewed as a game by assuming that the operator of one vehicle has perfect knowledge of the state of the other, whereas the operator of the second vehicle is unaware of any impending danger. The situation envisioned is that of an encounter between a commercial aircraft and a small light aircraft. This worse case situation is examined to determine the conditions under which the commercial aircraft should execute a collision avoidance maneuver. Three different zones of vulnerability are defined and the boundaries, or barriers, between these zones are determined for a typical aircraft encounter. A discussion of the methods used to obtain the results as well as some of the salient features associated with the resultant barriers is included.

  8. Time-dependent enhancement of inhibitory avoidance retention and MAPK activation by post-training infusion of nerve growth factor into CA1 region of hippocampus of adult rats.

    PubMed

    Walz, R; Lenz, G; Roesler, R; Vianna, M M; Martins, V; Brentani, R; Rodnight, R; Izquierdo, I

    2000-06-01

    Several studies have demonstrated that chronic intracerebroventricular nerve growth factor (NGF) infusion has a beneficial effect on cognitive performance of lesioned as well as old and developing animals. Here we investigate: (i) the effect of post-training infusion of NGF into the CA1 region of hippocampus on inhibitory avoidance (IA) retention in rats; (ii) the extension of the effect, in time and space, of NGF infusion into CA1 on the activity of mitogen-activated protein kinase (MAPK, syn: ERK1/2, p42/p44 MAPK). NGF was bilaterally injected into the CA1 regions of the dorsal hippocampus (0.05, 0.5 or 5.0 ng diluted in 0.5 microL of saline per side ) at 0, 120 or 360 min after IA training in rats. Retention testing was carried out 24 h after training. The injection of 5.0 and 0.5, but not 0.05, ng per side of NGF at 0 and 120 min after IA training enhanced IA retention. The highest dose used was ineffective when injected 360 min after training. The infusion of 0. 5 microL of NGF (5.0 ng) induced a significant enhancement of MAPK activity in hippocampal microslices; this enhancement was restricted to a volume with 0.8 mm radius at 30 min after injection. The MAPK activation was still seen 180 min after NGF infusion, although this value showed only a tendency. In conclusion, localized infusion of NGF into the CA1 region enhanced MAPK activity, restricted in time and space, and enhanced IA retention in a time- and dose-dependent manner.

  9. Alprazolam treatment of avoidant personality traits in social phobic patients.

    PubMed

    Reich, J; Noyes, R; Yates, W

    1989-03-01

    The authors examined the effect of alprazolam treatment on avoidant personality traits in 14 DSM-III-R social phobics. Six of the nine avoidant traits examined improved with treatment. However, all but one trait (avoiding social or occupational activities requiring interpersonal contact) returned to baseline levels posttreatment. Treatment response and intercorrelation of items indicated two traits that may represent a separate segment of avoidant personality: "No close friends or confidants outside of relatives and family members" and "Exaggerates the potential dangers or risks of everyday situations."

  10. Reducing Errors by Use of Redundancy in Gravity Measurements

    NASA Technical Reports Server (NTRS)

    Kulikov, Igor; Zak, Michail

    2004-01-01

    A methodology for improving gravity-gradient measurement data exploits the constraints imposed upon the components of the gravity-gradient tensor by the conditions of integrability needed for reconstruction of the gravitational potential. These constraints are derived from the basic equation for the gravitational potential and from mathematical identities that apply to the gravitational potential and its partial derivatives with respect to spatial coordinates. Consider the gravitational potential in a Cartesian coordinate system {x1,x2,x3}. If one measures all the components of the gravity-gradient tensor at all points of interest within a region of space in which one seeks to characterize the gravitational field, one obtains redundant information. One could utilize the constraints to select a minimum (that is, nonredundant) set of measurements from which the gravitational potential could be reconstructed. Alternatively, one could exploit the redundancy to reduce errors from noisy measurements. A convenient example is that of the selection of a minimum set of measurements to characterize the gravitational field at n3 points (where n is an integer) in a cube. Without the benefit of such a selection, it would be necessary to make 9n3 measurements because the gravitygradient tensor has 9 components at each point. The problem of utilizing the redundancy to reduce errors in noisy measurements is an optimization problem: Given a set of noisy values of the components of the gravity-gradient tensor at the measurement points, one seeks a set of corrected values - a set that is optimum in that it minimizes some measure of error (e.g., the sum of squares of the differences between the corrected and noisy measurement values) while taking account of the fact that the constraints must apply to the exact values. The problem as thus posed leads to a vector equation that can be solved to obtain the corrected values.

  11. Redundant Information and the Quantum-Classical Transition

    NASA Astrophysics Data System (ADS)

    Riedel, Charles Jess

    A state selected at random from the Hilbert space of a many-body system is overwhelmingly likely to exhibit highly non-classical correlations. For these typical states, half of the environment must be measured by an observer to determine the state of a given subsystem. The objectivity of classical reality—the fact that multiple observers can each agree on the state of a subsystem after measuring just a small fraction of its environment—implies that the correlations found in nature between macroscopic systems and their environments are very exceptional. This is understood through the redundant recording of information about the preferred states of a decohering system by its environment, a phenomenon known as quantum Darwinism. To see this in action in the real world, we first consider the ubiquitous case of blackbody illumination. We show that it exhibits fast and extensive proliferation of information about an object into the environment, yielding redundancies orders of magnitude larger than the exactly soluble models considered previously. Turning to a universe of qubits, we examine the conditions needed for the creation of branching states and study their demise through many-body interactions. We show that even constrained dynamics can suppress redundancies to the values typical of random states on relaxation timescales, and prove that these results hold exactly in the thermodynamic limit. Finally, we connect these ideas to the consistent histories framework. Building on the criterion of partial-trace consistency, we introduce a sensible notion of mutual information between a fragment of the universe and a history itself.

  12. Regulating Cognitive Control through Approach-Avoidance Motor Actions

    ERIC Educational Resources Information Center

    Koch, Severine; Holland, Rob W.; van Knippenberg, Ad

    2008-01-01

    In two studies, the regulatory function of approach-avoidance cues in activating cognitive control processes was investigated. It was hypothesized that avoidance motor actions, relative to approach motor actions, increase the recruitment of cognitive resources, resulting in better performance on tasks that draw on these capacities. In Study 1,…

  13. A collision avoidance system for a spaceplane manipulator arm

    NASA Technical Reports Server (NTRS)

    Sciomachen, Anna; Magnani, Piergiovanni

    1989-01-01

    Part of the activity in the area of collision avoidance related to the Hermes spaceplane is reported. A collision avoidance software system which was defined, developed and implemented in this project is presented. It computes the intersection between the solids representing the arm, the payload, and the objects. It is feasible with respect to the resources available on board, considering its performance.

  14. Analytical redundancy and the design of robust failure detection systems

    NASA Technical Reports Server (NTRS)

    Chow, E. Y.; Willsky, A. S.

    1984-01-01

    The Failure Detection and Identification (FDI) process is viewed as consisting of two stages: residual generation and decision making. It is argued that a robust FDI system can be achieved by designing a robust residual generation process. Analytical redundancy, the basis for residual generation, is characterized in terms of a parity space. Using the concept of parity relations, residuals can be generated in a number of ways and the design of a robust residual generation process can be formulated as a minimax optimization problem. An example is included to illustrate this design methodology. Previously announcedd in STAR as N83-20653

  15. Reconsidering the role of orthographic redundancy in visual word recognition

    PubMed Central

    Chetail, Fabienne

    2015-01-01

    Humans are known to continuously extract regularities from the flow of stimulation. This occurs in many facets of behavior, including reading. In spite of the ubiquitous evidence that readers become sensitive to orthographic regularities after very little exposure to print, the role of orthographic regularities receives at best a peripheral status in current theories of orthographic processing. In the present article, after the presentation of previous evidence on orthographic redundancy, the hypothesis that orthographic regularities may play a prominent role in word perception is developed. PMID:26042074

  16. Coded aperture imaging with self-supporting uniformly redundant arrays

    DOEpatents

    Fenimore, Edward E.

    1983-01-01

    A self-supporting uniformly redundant array pattern for coded aperture imaging. The present invention utilizes holes which are an integer times smaller in each direction than holes in conventional URA patterns. A balance correlation function is generated where holes are represented by 1's, nonholes are represented by -1's, and supporting area is represented by 0's. The self-supporting array can be used for low energy applications where substrates would greatly reduce throughput. The balance correlation response function for the self-supporting array pattern provides an accurate representation of the source of nonfocusable radiation.

  17. Intercommunications in Real Time, Redundant, Distributed Computer System

    NASA Technical Reports Server (NTRS)

    Zanger, H.

    1980-01-01

    An investigation into the applicability of fiber optic communication techniques to real time avionic control systems, in particular the total automatic flight control system used for the VSTOL aircraft is presented. The system consists of spatially distributed microprocessors. The overall control function is partitioned to yield a unidirectional data flow between the processing elements (PE). System reliability is enhanced by the use of triple redundancy. Some general overall system specifications are listed here to provide the necessary background for the requirements of the communications system.

  18. A Star Pattern Recognition Method Based on Decreasing Redundancy Matching

    NASA Astrophysics Data System (ADS)

    Yao, Lu; Xiao-xiang, Zhang; Rong-yu, Sun

    2016-04-01

    During the optical observation of space objects, it is difficult to enable the background stars to get matched when the telescope pointing error and tracking error are significant. Based on the idea of decreasing redundancy matching, an effective recognition method for background stars is proposed in this paper. The simulative images under different conditions and the observed images are used to verify the proposed method. The experimental results show that the proposed method has raised the rate of recognition and reduced the time consumption, it can be used to match star patterns accurately and rapidly.

  19. Neural substrates of approach-avoidance conflict decision-making

    PubMed Central

    Aupperle, Robin L.; Melrose, Andrew J.; Francisco, Alex; Paulus, Martin P.; Stein, Murray B.

    2014-01-01

    Animal approach-avoidance conflict paradigms have been used extensively to operationalize anxiety, quantify the effects of anxiolytic agents, and probe the neural basis of fear and anxiety. Results from human neuroimaging studies support that a frontal-striatal-amygdala neural circuitry is important for approach-avoidance learning. However, the neural basis of decision-making is much less clear in this context. Thus, we combined a recently developed human approach-avoidance paradigm with functional magnetic resonance imaging (fMRI) to identify neural substrates underlying approach-avoidance conflict decision-making. Fifteen healthy adults completed the approach-avoidance conflict (AAC) paradigm during fMRI. Analyses of variance were used to compare conflict to non-conflict (avoid-threat and approach-reward) conditions and to compare level of reward points offered during the decision phase. Trial-by-trial amplitude modulation analyses were used to delineate brain areas underlying decision-making in the context of approach/avoidance behavior. Conflict trials as compared to the non-conflict trials elicited greater activation within bilateral anterior cingulate cortex (ACC), anterior insula, and caudate, as well as right dorsolateral prefrontal cortex. Right caudate and lateral PFC activation was modulated by level of reward offered. Individuals who showed greater caudate activation exhibited less approach behavior. On a trial-by-trial basis, greater right lateral PFC activation related to less approach behavior. Taken together, results suggest that the degree of activation within prefrontal-striatal-insula circuitry determines the degree of approach versus avoidance decision-making. Moreover, the degree of caudate and lateral PFC activation is related to individual differences in approach-avoidance decision-making. Therefore, the AAC paradigm is ideally suited to probe anxiety-related processing differences during approach-avoidance decision-making. PMID:25224633

  20. T cell epitope redundancy: cross-conservation of the TCR face between pathogens and self and its implications for vaccines and autoimmunity.

    PubMed

    Moise, Leonard; Beseme, Sarah; Tassone, Ryan; Liu, Rui; Kibria, Farzana; Terry, Frances; Martin, William; De Groot, Anne S

    2016-05-01

    T cells are extensively trained on 'self' in the thymus and then move to the periphery, where they seek out and destroy infections and regulate immune response to self-antigens. T cell receptors (TCRs) on T cells' surface recognize T cell epitopes, short linear strings of amino acids presented by antigen-presenting cells. Some of these epitopes activate T effectors, while others activate regulatory T cells. It was recently discovered that T cell epitopes that are highly conserved on their TCR face with human genome sequences are often associated with T cells that regulate immune response. These TCR-cross-conserved or 'redundant epitopes' are more common in proteins found in pathogens that have co-evolved with humans than in other non-commensal pathogens. Epitope redundancy might be the link between pathogens and autoimmune disease. This article reviews recently published data and addresses epitope redundancy, the "elephant in the room" for vaccine developers and T cell immunologists.

  1. Biochar aging reduces earthworm avoidance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biochar, a black carbon substance produced by the pyrolysis of organic feedstocks, has been used in many soil improvement strategies ranging from nutrient addition to sequestration of C. Simple toxicity studies and laboratory preference/avoidance assays are recommended but results rarely reported. ...

  2. Avoided cost pricing: who wins

    SciTech Connect

    Einhorn, M.A.

    1985-05-30

    This article calls for a reevaluation of current Federal Energy Regulatory Commission regulations on the calculation of avoided cost rates for sales of power to utilities by small producers in the light of market conditions not contemplated at the time of the regulations' adoption. 8 references.

  3. Avoiding plagiarism in academic writing.

    PubMed

    Anderson, Irene

    Plagiarism means taking the work of another and presenting it as one's own, resulting in potential upset for the original author and disrepute for the professions involved. This article aims to explore the issue of plagiarism and some mechanisms for detection and avoidance.

  4. Drosophila evolution challenges postulated redundancy in the E(spl) gene complex.

    PubMed

    Maier, D; Marte, B M; Schäfer, W; Yu, Y; Preiss, A

    1993-06-15

    The Enhancer of split [E(spl)] gene complex belongs to the class of neurogenic loci, which, in a concerted action, govern neurogenesis in Drosophila. Two genetically distinct functions, vital and neurogenic, reside within the complex defined by lethal mutations in the l(3) gro gene and by the typical neurogenic phenotype of deletions, respectively. Such deletions always affect several of the many embryonically active genes in the region, which cannot be mutated separately to lethality. Seven of these genes are extremely similar at the transcription and sequence level sharing the basic helix-loop-helix (bHLH) motif of transcriptional regulators. While these E(spl) bHLH genes seem to be required collectively for neurogenesis, they are nonessential individually, suggesting functional redundancy of the encoded gene products. No specific functions could yet be ascribed to any of the other genes located within the complex. One might expect these apparently dispensable genes, as well as the supposedly redundant bHLH genes, to be under little evolutionary constraint and, thus, to evolve most rapidly. However, we find the entire E(spl) gene complex highly conserved during Drosophila evolution, indicating that all the genes as well as their organization are of functional importance.

  5. Cryptic biodiversity effects: importance of functional redundancy revealed through addition of food web complexity.

    PubMed

    Philpott, Stacy M; Pardee, Gabriella L; Gonthier, David J

    2012-05-01

    Interactions between predators and the degree of functional redundancy among multiple predator species may determine whether herbivores experience increased or decreased predation risk. Specialist parasites can modify predator behavior, yet rarely have cascading effects on multiple predator species and prey been evaluated. We examined influences of specialist phorid parasites (Pseudacteon spp.) on three predatory ant species and herbivores in a coffee agroecosystem. Specifically, we examined whether changes in ant richness affected fruit damage by the coffee berry borer (Hypothenemus hampei) and whether phorids altered multi-predator effects. Each ant species reduced borer damage, and without phorids, increasing predator richness did not further decrease borer damage. However, with phorids, activity of one ant species was reduced, indicating that the presence of multiple ant species was necessary to limit borer damage. In addition, phorid presence revealed synergistic effects of multiple ant species, not observed without the presence of this parasite. Thus, a trait-mediated cascade resulting from a parasite-induced predator behavioral change revealed the importance of functional redundancy, predator diversity, and food web complexity for control of this important pest.

  6. The prelimbic cortex contributes to the down-regulation of attention toward redundant cues.

    PubMed

    Sharpe, Melissa J; Killcross, Simon

    2014-04-01

    Previous research suggests disruption of activity in the prelimbic (PL) cortex produces deficits in tasks requiring preferential attention toward cues that are good predictors of an event. By manipulating cue predictive power, we clarify this role using Pavlovian conditioning. Experiment 1a showed pretraining excitotoxic lesions of the PL cortex disrupted the ability of animals to distribute attention across stimuli conditioned in compound. Experiment 1b demonstrated that these lesions did not affect the ability to block learning about a stimulus when it was presented simultaneously with another stimulus that was previously paired with the outcome. However, in a subsequent test, PL-lesioned animals learnt about this blocked cue faster than sham-lesioned animals when this stimulus alone was paired with reinforcement, suggesting these animals did not down-regulate attention toward the redundant cue during blocking. Experiment 2 tested this hypothesis using an unblocking procedure designed to explicitly reveal a down-regulation of attention during blocking. In this, sham-lesioned animals were shown to down-regulate attention during blocking. PL-lesioned animals did not exhibit this effect. We propose that observed deficits are the result of a specific deficit in down-regulating attention toward redundant cues, indicating the disruption of an attentional process described in Mackintosh's (Mackintosh NJ. 1975. Psychol Review. 82:276) attentional theory.

  7. The prelimbic cortex contributes to the down-regulation of attention toward redundant cues.

    PubMed

    Sharpe, Melissa J; Killcross, Simon

    2014-04-01

    Previous research suggests disruption of activity in the prelimbic (PL) cortex produces deficits in tasks requiring preferential attention toward cues that are good predictors of an event. By manipulating cue predictive power, we clarify this role using Pavlovian conditioning. Experiment 1a showed pretraining excitotoxic lesions of the PL cortex disrupted the ability of animals to distribute attention across stimuli conditioned in compound. Experiment 1b demonstrated that these lesions did not affect the ability to block learning about a stimulus when it was presented simultaneously with another stimulus that was previously paired with the outcome. However, in a subsequent test, PL-lesioned animals learnt about this blocked cue faster than sham-lesioned animals when this stimulus alone was paired with reinforcement, suggesting these animals did not down-regulate attention toward the redundant cue during blocking. Experiment 2 tested this hypothesis using an unblocking procedure designed to explicitly reveal a down-regulation of attention during blocking. In this, sham-lesioned animals were shown to down-regulate attention during blocking. PL-lesioned animals did not exhibit this effect. We propose that observed deficits are the result of a specific deficit in down-regulating attention toward redundant cues, indicating the disruption of an attentional process described in Mackintosh's (Mackintosh NJ. 1975. Psychol Review. 82:276) attentional theory. PMID:23236210

  8. Statistical redundancy of instantaneous phases: theory and application to the seismic ambient wavefield

    NASA Astrophysics Data System (ADS)

    Gaudot, Ianis; Beucler, Éric; Mocquet, Antoine; Schimmel, Martin; Le Feuvre, Mathieu

    2016-04-01

    close to zero for most time lags, except for specific time windows in which a clear signal emerges. Converting mean overall coherences into geographical locations and using a standard 3.5 km/s group velocity value, the maximum coherence is obtained with a source located at 5.5°N, 1.5°E, in a very good agreement with previous locations found in the literature. This result demonstrates that our approach enables us to properly localize persistent sources, and to quantify their contribution to the overall seismic ambient wavefield. The strength of the phase coherence statistics relies in its ability to quantify the redundancy of a given phase among a set of ambient noise cross-correlations without using classical amplitude normalization processing schemes. The method has various useful applications in seismic noise-based studies (tomography and/or source characterization). Depending on the application, the method may be used to exclude either poorly contributing traces for efficient signal extraction, or to exclude highly contributing traces to avoid contamination from a persistent signal.

  9. Accessory cells with a veiled morphology and movement pattern generated from monocytes after avoidance of plastic adherence and of NADPH oxidase activation. A comparison with GM-CSF/IL-4-induced monocyte-derived dendritic cells.

    PubMed

    Ruwhof, Cindy; Canning, Martha O; Grotenhuis, Kristel; de Wit, Harm J; Florencia, Zenovia Z; de Haan-Meulman, Meeny; Drexhage, Hemmo A

    2002-07-01

    Veiled cells (VC) present in afferent lymph transport antigen from the periphery to the draining lymph nodes. Although VC in lymph form a heterogeneous population, some of the cells clearly belong on morphological grounds to the Langerhans cell (LC)/ dendritic cell (DC) series. Here we show that culturing monocytes for 24 hrs while avoiding plastic adherence (polypropylene tubes) and avoiding the activation of NADPH oxidase (blocking agents) results in the generation of a population of veiled accessory cells. The generated VC were actively moving cells like lymph-borne VC in vivo. The monocyte (mo)-derived VC population existed of CD14(dim/-) and CD14(brighT) cells. Of these the CD14(dim/-) VC were as good in stimulating allogeneic T cell proliferation as immature DC (iDC) obtained after one week of adherent culture of monocytes in granulocyte-macrophage-colony stimulating factor (GM-CSF)/interleukin (IL)-4. This underscores the accessory cell function of the mo-derived CD14(dim/-) VC. Although the CD14(dim/-)VC had a modest expression of the DC-specific marker CD83 and were positive for S100, expression of the DC-specific markers CD1a, Langerin, DC-SIGN, and DC-LAMP were absent. This indicates that the here generated CD14(dim/-) VC can not be considered as classical LC/DC. It was also impossible to turn the CD14(dim/-) mo-derived VC population into typical DC by culture for one week in GM-CSF/IL-4 or LPS. In fact the cells died tinder such circumstances, gaining some macrophage characteristics before dying. The IL-12 production from mo-derived CD14(dim/-) VC was lower, whereas the production of IL-10 was higher as compared to iDC. Consequently the T cells that were stimulated by these mo-derived VC produced less IFN-gamma as compared with T cells stimulated by iDC. Our data indicate that it is possible to rapidly generate a population of CD14(dim/-) veiled accessory cells from monocytes. The marker pattern and cytokine production of these VC indicate that this

  10. Guanosine impairs inhibitory avoidance performance in rats.

    PubMed

    Roesler, R; Vianna, M R; Lara, D R; Izquierdo, I; Schmidt, A P; Souza, D O

    2000-08-01

    The nucleoside guanosine, previously found to exert trophic and neuroprotective effects, was found to impair retention of inhibitory avoidance responses, with a complete effect at 7.5 mg/kg i.p. pretraining. Treated animals, when retrained 1 week later, showed normal learning ability. Guanosine injected immediately after training or pretest did not alter retention latency. Combined pretraining and pretest treatments with guanosine failed to reverse its amnestic effect, excluding the contribution of state dependency. Open field parameters and shock sensitivity were mostly unaltered by guanosine. These results suggest an amnestic effect of guanosine on inhibitory avoidance in rats, in a pattern compatible with inhibition of glutamatergic activity. However, the mechanism for the amnestic effect of guanosine is yet to be elucidated.

  11. Inter-Domain Redundancy Path Computation Methods Based on PCE

    NASA Astrophysics Data System (ADS)

    Hayashi, Rie; Oki, Eiji; Shiomoto, Kohei

    This paper evaluates three inter-domain redundancy path computation methods based on PCE (Path Computation Element). Some inter-domain paths carry traffic that must be assured of high quality and high reliability transfer such as telephony over IP and premium virtual private networks (VPNs). It is, therefore, important to set inter-domain redundancy paths, i. e. primary and secondary paths. The first scheme utilizes an existing protocol and the basic PCE implementation. It does not need any extension or modification. In the second scheme, PCEs make a virtual shortest path tree (VSPT) considering the candidates of primary paths that have corresponding secondary paths. The goal is to reduce blocking probability; corresponding secondary paths may be found more often after a primary path is decided; no protocol extension is necessary. In the third scheme, PCEs make a VSPT considering all candidates of primary and secondary paths. Blocking probability is further decreased since all possible candidates are located, and the sum of primary and secondary path cost is reduced by choosing the pair with minimum cost among all path pairs. Numerical evaluations show that the second and third schemes offer only a few percent reduction in blocking probability and path pair total cost, while the overheads imposed by protocol revision and increase of the amount of calculation and information to be exchanged are large. This suggests that the first scheme, the most basic and simple one, is the best choice.

  12. Redundancy of myostatin and growth/differentiation factor 11 function

    PubMed Central

    McPherron, Alexandra C; Huynh, Thanh V; Lee, Se-Jin

    2009-01-01

    Background Myostatin (Mstn) and growth/differentiation factor 11 (Gdf11) are highly related transforming growth factor β (TGFβ) family members that play important roles in regulating embryonic development and adult tissue homeostasis. Despite their high degree of sequence identity, targeted mutations in these genes result in non-overlapping phenotypes affecting distinct biological processes. Loss of Mstn in mice causes a doubling of skeletal muscle mass while loss of Gdf11 in mice causes dramatic anterior homeotic transformations of the axial skeleton, kidney agenesis, and an increase in progenitor cell number in several tissues. In order to investigate the possible functional redundancy of myostatin and Gdf11, we analyzed the effect of eliminating the functions of both of these signaling molecules. Results We show that Mstn-/- Gdf11-/- mice have more extensive homeotic transformations of the axial skeleton than Gdf11-/- mice in addition to skeletal defects not seen in single mutants such as extra forelimbs. We also show that deletion of Gdf11 specifically in skeletal muscle in either Mstn+/+ or Mstn-/- mice does not affect muscle size, fiber number, or fiber type. Conclusion These results provide evidence that myostatin and Gdf11 have redundant functions in regulating skeletal patterning in mice but most likely not in regulating muscle size. PMID:19298661

  13. The Evolution of Functionally Redundant Species; Evidence from Beetles

    PubMed Central

    Scheffer, Marten; Vergnon, Remi; van Nes, Egbert H.; Cuppen, Jan G. M.; Peeters, Edwin T. H. M.; Leijs, Remko; Nilsson, Anders N.

    2015-01-01

    While species fulfill many different roles in ecosystems, it has been suggested that numerous species might actually share the same function in a near neutral way. So-far, however, it is unclear whether such functional redundancy really exists. We scrutinize this question using extensive data on the world’s 4168 species of diving beetles. We show that across the globe these animals have evolved towards a small number of regularly-spaced body sizes, and that locally co-existing species are either very similar in size or differ by at least 35%. Surprisingly, intermediate size differences (10–20%) are rare. As body-size strongly reflects functional aspects such as the food that these generalist predators can eat, these beetles thus form relatively distinct groups of functional look-a-likes. The striking global regularity of these patterns support the idea that a self-organizing process drives such species-rich groups to self-organize evolutionary into clusters where functional redundancy ensures resilience through an insurance effect. PMID:26447476

  14. The Evolution of Functionally Redundant Species; Evidence from Beetles.

    PubMed

    Scheffer, Marten; Vergnon, Remi; van Nes, Egbert H; Cuppen, Jan G M; Peeters, Edwin T H M; Leijs, Remko; Nilsson, Anders N

    2015-01-01

    While species fulfill many different roles in ecosystems, it has been suggested that numerous species might actually share the same function in a near neutral way. So-far, however, it is unclear whether such functional redundancy really exists. We scrutinize this question using extensive data on the world's 4168 species of diving beetles. We show that across the globe these animals have evolved towards a small number of regularly-spaced body sizes, and that locally co-existing species are either very similar in size or differ by at least 35%. Surprisingly, intermediate size differences (10-20%) are rare. As body-size strongly reflects functional aspects such as the food that these generalist predators can eat, these beetles thus form relatively distinct groups of functional look-a-likes. The striking global regularity of these patterns support the idea that a self-organizing process drives such species-rich groups to self-organize evolutionary into clusters where functional redundancy ensures resilience through an insurance effect.

  15. Simplifier: a web tool to eliminate redundant NGS contigs

    PubMed Central

    Ramos, Rommel Thiago Jucá; Carneiro, Adriana Ribeiro; Azevedo, Vasco; Schneider, Maria Paula; Barh, Debmalya; Silva, Artur

    2012-01-01

    Modern genomic sequencing technologies produce a large amount of data with reduced cost per base; however, this data consists of short reads. This reduction in the size of the reads, compared to those obtained with previous methodologies, presents new challenges, including a need for efficient algorithms for the assembly of genomes from short reads and for resolving repetitions. Additionally after abinitio assembly, curation of the hundreds or thousands of contigs generated by assemblers demands considerable time and computational resources. We developed Simplifier, a stand-alone software that selectively eliminates redundant sequences from the collection of contigs generated by ab initio assembly of genomes. Application of Simplifier to data generated by assembly of the genome of Corynebacterium pseudotuberculosis strain 258 reduced the number of contigs generated by ab initio methods from 8,004 to 5,272, a reduction of 34.14%; in addition, N50 increased from 1 kb to 1.5 kb. Processing the contigs of Escherichia coli DH10B with Simplifier reduced the mate-paired library 17.47% and the fragment library 23.91%. Simplifier removed redundant sequences from datasets produced by assemblers, thereby reducing the effort required for finalization of genome assembly in tests with data from Prokaryotic organisms. Availability Simplifier is available at http://www.genoma.ufpa.br/rramos/softwares/simplifier.xhtmlIt requires Sun jdk 6 or higher. PMID:23275695

  16. The Evolution of Functionally Redundant Species; Evidence from Beetles.

    PubMed

    Scheffer, Marten; Vergnon, Remi; van Nes, Egbert H; Cuppen, Jan G M; Peeters, Edwin T H M; Leijs, Remko; Nilsson, Anders N

    2015-01-01

    While species fulfill many different roles in ecosystems, it has been suggested that numerous species might actually share the same function in a near neutral way. So-far, however, it is unclear whether such functional redundancy really exists. We scrutinize this question using extensive data on the world's 4168 species of diving beetles. We show that across the globe these animals have evolved towards a small number of regularly-spaced body sizes, and that locally co-existing species are either very similar in size or differ by at least 35%. Surprisingly, intermediate size differences (10-20%) are rare. As body-size strongly reflects functional aspects such as the food that these generalist predators can eat, these beetles thus form relatively distinct groups of functional look-a-likes. The striking global regularity of these patterns support the idea that a self-organizing process drives such species-rich groups to self-organize evolutionary into clusters where functional redundancy ensures resilience through an insurance effect. PMID:26447476

  17. Information theory and artificial grammar learning: inferring grammaticality from redundancy.

    PubMed

    Jamieson, Randall K; Nevzorova, Uliana; Lee, Graham; Mewhort, D J K

    2016-03-01

    In artificial grammar learning experiments, participants study strings of letters constructed using a grammar and then sort novel grammatical test exemplars from novel ungrammatical ones. The ability to distinguish grammatical from ungrammatical strings is often taken as evidence that the participants have induced the rules of the grammar. We show that judgements of grammaticality are predicted by the local redundancy of the test strings, not by grammaticality itself. The prediction holds in a transfer test in which test strings involve different letters than the training strings. Local redundancy is usually confounded with grammaticality in stimuli widely used in the literature. The confounding explains why the ability to distinguish grammatical from ungrammatical strings has popularized the idea that participants have induced the rules of the grammar, when they have not. We discuss the judgement of grammaticality task in terms of attribute substitution and pattern goodness. When asked to judge grammaticality (an inaccessible attribute), participants answer an easier question about pattern goodness (an accessible attribute). PMID:25828458

  18. Low multifunctional redundancy of soil fungal diversity at multiple scales.

    PubMed

    Mori, Akira S; Isbell, Forest; Fujii, Saori; Makoto, Kobayashi; Matsuoka, Shunsuke; Osono, Takashi

    2016-03-01

    Theory suggests that biodiversity might help sustain multiple ecosystem functions. To evaluate possible biodiversity-multifunctionality relationships in a natural setting, we considered different spatial scales of diversity metrics for soil fungi in the northern forests of Japan. We found that multifunctionality increased with increasing local species richness, suggesting a limited degree of multifunctional redundancy. This diversity-multifunctionality relationship was independent of the compositional uniqueness of each community. However, we still found the importance of community composition, because there was a positive correlation between community dissimilarity and multifunctional dissimilarity across the landscape. This result suggests that functional redundancy can further decrease when spatial variations in identities of both species and functions are simultaneously considered at larger spatial scales. We speculate that different scales of diversity could provide multiple levels of insurance against the loss of functioning if high-levels of local species diversity and compositional variation across locations are both maintained. Alternatively, making species assemblages depauperate may result in the loss of multifunctionality. PMID:26689733

  19. Reward-based learning of a redundant task.

    PubMed

    Tamagnone, Irene; Casadio, Maura; Sanguineti, Vittorio

    2013-06-01

    Motor skill learning has different components. When we acquire a new motor skill we have both to learn a reliable action-value map to select a highly rewarded action (task model) and to develop an internal representation of the novel dynamics of the task environment, in order to execute properly the action previously selected (internal model). Here we focus on a 'pure' motor skill learning task, in which adaptation to a novel dynamical environment is negligible and the problem is reduced to the acquisition of an action-value map, only based on knowledge of results. Subjects performed point-to-point movement, in which start and target positions were fixed and visible, but the score provided at the end of the movement depended on the distance of the trajectory from a hidden viapoint. Subjects did not have clues on the correct movement other than the score value. The task is highly redundant, as infinite trajectories are compatible with the maximum score. Our aim was to capture the strategies subjects use in the exploration of the task space and in the exploitation of the task redundancy during learning. The main findings were that (i) subjects did not converge to a unique solution; rather, their final trajectories are determined by subject-specific history of exploration. (ii) with learning, subjects reduced the trajectory's overall variability, but the point of minimum variability gradually shifted toward the portion of the trajectory closer to the hidden via-point. PMID:24187205

  20. Analysis of wing truss stresses including the effect of redundancies

    NASA Technical Reports Server (NTRS)

    Warner, E P; Miller, R G

    1921-01-01

    Airplane wing trusses are generally designed to contain redundant members (stagger wires and external drag wires) which, according to common practice, are not taken into account in calculations, so as to simplify the stress analysis by rendering the structure statically determinate. A more accurate method, in which the redundancies are included, involves a solution by means of Castigliano's method of least work. For the purpose of demonstrating the practical application of the method of least work this report presents examples for stresses of several cases of loading worked out for a structure similar to that of the Curtiss JN-4h. Case 1 was taken as the condition of velocity of 100 miles per hour combined with the angle of attack of maximum lift. Case 1a assumed the same loading but neglected the distortion of wooden members in the least-work analysis. So little error was involved in case 1a that this simplified method was employed for each succeeding case. Case 2 assumed a diving speed of 120 miles per hour and an angle of attack of no lift. Case 3 was worked out for the conditions imposed by the sand load recommended in NACA technical note no. 6.

  1. Redundancy complicates the definition of essential genes for vaccinia virus.

    PubMed

    Dobson, Bianca M; Tscharke, David C

    2015-11-01

    Vaccinia virus (VACV) genes are characterized as either essential or non-essential for growth in culture. It seems intuitively obvious that if a gene can be deleted without imparting a growth defect in vitro it does not have a function related to basic replication or spread. However, this interpretation relies on the untested assumption that there is no redundancy across the genes that have roles in growth in cell culture. First, we provide a comprehensive summary of the literature that describes the essential genes of VACV. Next, we looked for interactions between large blocks of non-essential genes located at the ends of the genome by investigating sets of VACVs with large deletions at the genomic termini. Viruses with deletions at either end of the genome behaved as expected, exhibiting only mild or host-range defects. In contrast, combining deletions at both ends of the genome for the VACV Western Reserve (WR) strain caused a devastating growth defect on all cell lines tested. Unexpectedly, we found that the well-studied VACV growth factor homologue encoded by C11R has a role in growth in vitro that is exposed when 42 genes are absent from the left end of the VACV WR genome. These results demonstrate that some non-essential genes contribute to basic viral growth, but redundancy means these functions are not revealed by single-gene-deletion mutants.

  2. Joint Torque Reduction of a Three Dimensional Redundant Planar Manipulator

    PubMed Central

    Yahya, Samer; Moghavvemi, Mahmoud; Almurib, Haider Abbas F.

    2012-01-01

    Research on joint torque reduction in robot manipulators has received considerable attention in recent years. Minimizing the computational complexity of torque optimization and the ability to calculate the magnitude of the joint torque accurately will result in a safe operation without overloading the joint actuators. This paper presents a mechanical design for a three dimensional planar redundant manipulator with the advantage of the reduction in the number of motors needed to control the joint angle, leading to a decrease in the weight of the manipulator. Many efforts have been focused on decreasing the weight of manipulators, such as using lightweight joints design or setting the actuators at the base of the manipulator and using tendons for the transmission of power to these joints. By using the design of this paper, only three motors are needed to control any n degrees of freedom in a three dimensional planar redundant manipulator instead of n motors. Therefore this design is very effective to decrease the weight of the manipulator as well as the number of motors needed to control the manipulator. In this paper, the torque of all the joints are calculated for the proposed manipulator (with three motors) and the conventional three dimensional planar manipulator (with one motor for each degree of freedom) to show the effectiveness of the proposed manipulator for decreasing the weight of the manipulator and minimizing driving joint torques. PMID:22969326

  3. Reward-based learning of a redundant task.

    PubMed

    Tamagnone, Irene; Casadio, Maura; Sanguineti, Vittorio

    2013-06-01

    Motor skill learning has different components. When we acquire a new motor skill we have both to learn a reliable action-value map to select a highly rewarded action (task model) and to develop an internal representation of the novel dynamics of the task environment, in order to execute properly the action previously selected (internal model). Here we focus on a 'pure' motor skill learning task, in which adaptation to a novel dynamical environment is negligible and the problem is reduced to the acquisition of an action-value map, only based on knowledge of results. Subjects performed point-to-point movement, in which start and target positions were fixed and visible, but the score provided at the end of the movement depended on the distance of the trajectory from a hidden viapoint. Subjects did not have clues on the correct movement other than the score value. The task is highly redundant, as infinite trajectories are compatible with the maximum score. Our aim was to capture the strategies subjects use in the exploration of the task space and in the exploitation of the task redundancy during learning. The main findings were that (i) subjects did not converge to a unique solution; rather, their final trajectories are determined by subject-specific history of exploration. (ii) with learning, subjects reduced the trajectory's overall variability, but the point of minimum variability gradually shifted toward the portion of the trajectory closer to the hidden via-point.

  4. Successive positive contrast in one-way avoidance behavior with Roman low-avoidance rats.

    PubMed

    Maldonado, A; Torres, C; Escarabajal, M D; Cándido, A; de la Torre, L; Gómez, M J; Tobeña, A; Fernández-Teruel, A

    2007-04-23

    The inbred Roman High- (RHA-I) and Roman Low-Avoidance (RLA-I) rats, psychogenetically selected for rapid (RHA-I) vs. extremely poor (RLA-I) acquisition of two-way active avoidance, exhibit a lower or a higher level of fearfulness, respectively, that can be observed in many laboratory anxiety models. The present study analyzed the performance of female RLA-I and RHA-I rats in a successive positive contrast situation induced during one-way avoidance learning. Three groups of RLA-I and three of RHA-I rats (1-30, 30-30 and 1-1 groups, the numbers stand for the time spent in the safe compartment during the first and second phase of training) were trained to avoid an electric foot-shock administered in a "danger" compartment, by running from this compartment to a "safe" one. Only RLA-I rats showed a significant positive contrast effect, in such a way that the reinforcement increase from the lower (1 s spent in safety) to the higher reward (30 s) led to a response enhancement, surpassing the performance of rats trained with the low (1-1 s) or the high (30-30 s) reward from the beginning of training. The results are discussed in the context of an opponent process theory based upon the interaction between the motivational strength of fear and the incentive value of relief taking place during one-way avoidance learning.

  5. The effect of a redundant color code on an overlearned identification task

    NASA Technical Reports Server (NTRS)

    Obrien, Kevin

    1992-01-01

    The possibility of finding redundancy gains with overlearned tasks was examined using a paradigm varying familiarity with the stimulus set. Redundant coding in a multidimensional stimulus was demonstrated to result in increased identification accuracy and decreased latency of identification when compared to stimuli varying on only one dimension. The advantages attributable to redundant coding are referred to as redundancy gain and were found for a variety of stimulus dimension combinations, including the use of hue or color as one of the dimensions. Factors that have affected redundancy gain include the discriminability of the levels of one stimulus dimension and the level of stimulus-to-response association. The results demonstrated that response time is in part a function of familiarity, but no effect of redundant color coding was demonstrated. Implications of research on coding in identification tasks for display design are discussed.

  6. Method and system for redundancy management of distributed and recoverable digital control system

    NASA Technical Reports Server (NTRS)

    Stange, Kent (Inventor); Hess, Richard (Inventor); Kelley, Gerald B (Inventor); Rogers, Randy (Inventor)

    2012-01-01

    A method and system for redundancy management is provided for a distributed and recoverable digital control system. The method uses unique redundancy management techniques to achieve recovery and restoration of redundant elements to full operation in an asynchronous environment. The system includes a first computing unit comprising a pair of redundant computational lanes for generating redundant control commands. One or more internal monitors detect data errors in the control commands, and provide a recovery trigger to the first computing unit. A second redundant computing unit provides the same features as the first computing unit. A first actuator control unit is configured to provide blending and monitoring of the control commands from the first and second computing units, and to provide a recovery trigger to each of the first and second computing units. A second actuator control unit provides the same features as the first actuator control unit.

  7. Rapid jamming avoidance in biosonar.

    PubMed

    Gillam, Erin H; Ulanovsky, Nachum; McCracken, Gary F

    2007-03-01

    The sonar systems of bats and dolphins are in many ways superior to man-made sonar and radar systems, and considerable effort has been devoted to understanding the signal-processing strategies underlying these capabilities. A major feature determining the efficiency of sonar systems is the sensitivity to noise and jamming signals. Previous studies indicated that echolocating bats may adjust their signal structure to avoid jamming ('jamming avoidance response'; JAR). However, these studies relied on behavioural correlations and not controlled experiments. Here, we provide the first experimental evidence for JAR in bats. We presented bats (Tadarida brasiliensis) with 'playback stimuli' consisting of recorded echolocation calls at one of six frequencies. The bats exhibited a JAR by shifting their call frequency away from the presented playback frequency. When the approaching bats were challenged by an abrupt change in the playback stimulus, they responded by shifting their call frequencies upwards, away from the playback. Interestingly, even bats initially calling below the playback's frequency shifted their frequencies upwards, 'jumping' over the playback frequency. These spectral shifts in the bats' calls occurred often within less than 200 ms, in the first echolocation call emitted after the stimulus switch-suggesting that rapid jamming avoidance is important for the bat.

  8. Construction of customized redundant multiwavelet via increasing multiplicity for fault detection of rotating machinery

    NASA Astrophysics Data System (ADS)

    Chen, Jinglong; Zuo, Ming J.; Zi, Yanyang; He, Zhengjia

    2014-01-01

    Fault detection from the vibration measurement data of rotating machinery is significant for avoiding serious accidents. However, non-stationary vibration signal with a large amount of noise makes this task challenging. Multiwavelet not only owns the advantage on multi-resolution analysis but also can offer multiple wavelet basis functions. So it has the possibility of detecting various fault features preferably. However, the fixed basis functions which are not related to the given signal may lower the accuracy of fault detection. Moreover, another major intrinsic deficiency of multiwavelet lies in its critically sampled filter-bank, which causes shift-variance and is harmful to extract the feature of periodical impulses. To overcome these deficiencies, a new method called customized redundant multiwavelet (CRM) is constructed via increasing multiplicity (IM). IM is a simple method to design a series of changeable multiwavelet which are available for the subsequent optimization process. By the rule of the envelope spectrum entropy minimum principle, optimal multiwavelet is searched for. Based on the customized multiwavelet filters, the filters of CRM can be calculated by inserting zeros. The proposed method is applied to analyze the simulation, gearbox and rolling element bearing vibration signals. Compared with some other conventional methods, the results demonstrate that the proposed method possesses robust performance in detecting fault features of rotating machinery.

  9. Rapid avoidance acquisition in Wistar-Kyoto rats.

    PubMed

    Servatius, R J; Jiao, X; Beck, K D; Pang, K C H; Minor, T R

    2008-10-10

    The relationship between trait stress-sensitivity, avoidance acquisition and perseveration of avoidance was examined using male Wistar-Kyoto (WKY) and Sprague-Dawley (SD) rats. Behavior in an open field was measured prior to escape/avoidance (E/A) acquisition and extinction. E/A was assessed in a discrete trial lever-press protocol. The signal-shock interval was 60s with subsequent shocks delivered every 3s until a lever-press occurred. A 3-min flashing light safety signal was delivered contingent upon a lever-press (or failure to respond in 5 min). WKY rats displayed phenotypic low open field activity, but were clearly superior to SD rats in E/A performance. As avoidance responses were acquired and reached asymptotic performance, SD rats exhibited "warm up", that is, SD rats rarely made avoidance responses on the initial trial of a session, even though later trials were consistently accompanied with avoidance responses. In contrast, WKY rats did not show the "warm up" pattern and avoided on nearly all trials of a session including the initial trial. In addition to the superior acquisition of E/A, WKY rats demonstrated several other avoidance features that were different from SD rats. Although the rates of nonreinforced intertrial responses (ITRs) were relatively low and selective to the early safety period, WKY displayed more ITRs than SD rats. With removal of the shocks extinction was delayed in WKY rats, likely reflecting their nearly perfect avoidance performance. Even after extensive extinction, first trial avoidance and ITRs were evident in WKY rats. Thus, WKY rats have a unique combination of trait behavioral inhibition (low open field activity and stress sensitivity) and superior avoidance acquisition and response perseveration making this strain a good model to understand anxiety disorders.

  10. GEO Collision Avoidance using a Service Vehicle

    NASA Astrophysics Data System (ADS)

    Duncan, M.; Concha, M.

    2013-09-01

    Space Situational Awareness (SSA) is defined as the knowledge and characterization of all aspects of space. SSA is now a fundamental and critical component of space operations. The increased dependence on our space assets has in turn lead to a greater need for accurate, near real-time knowledge of all space activities. Key areas of SSA include improved tracking of small objects, determining the intent of maneuvering spacecraft, identifying all potential high risk conjunction events, and leveraging non-traditional sensors in support of the SSA mission. As the size of the space object population grows, the number of collision avoidance maneuvers grows. Moreover, as the SSA mission evolves to near real-time assessment and analysis, the need for new, more sophisticated collision avoidance methods are required. This paper demonstrates the utility of using a service vehicle to perform collision avoidance maneuver for GEO satellites. We present the planning and execution details required to successfully execute a maneuver; given the traditional conjunction analysis timelines. Various operational constraints and scenarios are considered as part of the demonstration. Development of the collision avoidance strategy is created using SpaceNav's collision risk management tool suite. This study aims to determine the agility required of any proposed servicing capability to provide collision avoidance within traditional conjunction analysis and collision avoidance operations timelines. Key trades and analysis items are given to be: 1. How do we fuse the spacecraft state data with the tracking data collected from the proximity sensor that resides on the servicing spacecraft? 2. How do we deal with the possibility that the collision threat for the event may change as the time to close approach is reduced? 3. Perform trade space of maneuver/thrust time versus achievable change in the spacecraft's orbit. 4. Perform trade space of proximity of service vehicle to spacecraft versus time

  11. A succession of theories: purging redundancy from disturbance theory.

    PubMed

    Pulsford, Stephanie A; Lindenmayer, David B; Driscoll, Don A

    2016-02-01

    The topics of succession and post-disturbance ecosystem recovery have a long and convoluted history. There is extensive redundancy within this body of theory, which has resulted in confusion, and the links among theories have not been adequately drawn. This review aims to distil the unique ideas from the array of theory related to ecosystem change in response to disturbance. This will help to reduce redundancy, and improve communication and understanding between researchers. We first outline the broad range of concepts that have developed over the past century to describe community change in response to disturbance. The body of work spans overlapping succession concepts presented by Clements in 1916, Egler in 1954, and Connell and Slatyer in 1977. Other theories describing community change include state and transition models, biological legacy theory, and the application of functional traits to predict responses to disturbance. Second, we identify areas of overlap of these theories, in addition to highlighting the conceptual and taxonomic limitations of each. In aligning each of these theories with one another, the limited scope and relative inflexibility of some theories becomes apparent, and redundancy becomes explicit. We identify a set of unique concepts to describe the range of mechanisms driving ecosystem responses to disturbance. We present a schematic model of our proposed synthesis which brings together the range of unique mechanisms that were identified in our review. The model describes five main mechanisms of transition away from a post-disturbance community: (i) pulse events with rapid state shifts; (ii) stochastic community drift; (iii) facilitation; (iv) competition; and (v) the influence of the initial composition of a post-disturbance community. In addition, stabilising processes such as biological legacies, inhibition or continuing disturbance may prevent a transition between community types. Integrating these six mechanisms with the functional

  12. Visual-motor processing: relationships among age, dimensional variation, and the use of information redundancy.

    PubMed

    Wallace, J R

    1984-09-01

    This study examined the hypothesis that age-related superiority in the ability to process complex stimuli was linked with age differences in the use of information redundancy. Seventy-two children (6-9 years of age) solved a series of puzzles that varied in complexity and redundancy. Significant correlations between age and completion times were found only for those puzzles that included some degree of information redundancy. Completion times on multidimensional puzzles that lacked redundancy were not significantly age related. PMID:6512512

  13. Exploiting stoichiometric redundancies for computational efficiency and network reduction.

    PubMed

    Ingalls, Brian P; Bembenek, Eric

    2015-01-01

    Analysis of metabolic networks typically begins with construction of the stoichiometry matrix, which characterizes the network topology. This matrix provides, via the balance equation, a description of the potential steady-state flow distribution. This paper begins with the observation that the balance equation depends only on the structure of linear redundancies in the network, and so can be stated in a succinct manner, leading to computational efficiencies in steady-state analysis. This alternative description of steady-state behaviour is then used to provide a novel method for network reduction, which complements existing algorithms for describing intracellular networks in terms of input-output macro-reactions (to facilitate bioprocess optimization and control). Finally, it is demonstrated that this novel reduction method can be used to address elementary mode analysis of large networks: the modes supported by a reduced network can capture the input-output modes of a metabolic module with significantly reduced computational effort.

  14. A global path planning approach for redundant manipulators

    NASA Technical Reports Server (NTRS)

    Seereeram, Sanjeev; Wen, J.

    1993-01-01

    A new approach for global path planning of redundant manipulators is proposed. It poses the path planning problem as a finite time nonlinear control problem. The solution is found by a Newton-Raphson type algorithm. This technique is capable of handling various goal task descriptions as well as incorporating both joint and task space constraints. The algorithm has shown promising preliminary results in planning joint path sequences for 3R and 4R planar robots to meet Cartesian tip tracking and goal endpoint planning. It is robust with respect to local path planning problems such as singularity considerations and local minimum problems. Repetitive joint path solutions for cyclic end-effector tasks are also generated. Eventual goals of this work include implementation on full spatial robots, as well as provision of an interface for supervisory input to aid in path planning for more complex problems.

  15. Testing and operating a multiprocessor chip with processor redundancy

    DOEpatents

    Bellofatto, Ralph E; Douskey, Steven M; Haring, Rudolf A; McManus, Moyra K; Ohmacht, Martin; Schmunkamp, Dietmar; Sugavanam, Krishnan; Weatherford, Bryan J

    2014-10-21

    A system and method for improving the yield rate of a multiprocessor semiconductor chip that includes primary processor cores and one or more redundant processor cores. A first tester conducts a first test on one or more processor cores, and encodes results of the first test in an on-chip non-volatile memory. A second tester conducts a second test on the processor cores, and encodes results of the second test in an external non-volatile storage device. An override bit of a multiplexer is set if a processor core fails the second test. In response to the override bit, the multiplexer selects a physical-to-logical mapping of processor IDs according to one of: the encoded results in the memory device or the encoded results in the external storage device. On-chip logic configures the processor cores according to the selected physical-to-logical mapping.

  16. Parallel, redundant circuit organization for homeostatic control of feeding behavior.

    PubMed

    Betley, J Nicholas; Cao, Zhen Fang Huang; Ritola, Kimberly D; Sternson, Scott M

    2013-12-01

    Neural circuits for essential natural behaviors are shaped by selective pressure to coordinate reliable execution of flexible goal-directed actions. However, the structural and functional organization of survival-oriented circuits is poorly understood due to exceptionally complex neuroanatomy. This is exemplified by AGRP neurons, which are a molecularly defined population that is sufficient to rapidly coordinate voracious food seeking and consumption behaviors. Here, we use cell-type-specific techniques for neural circuit manipulation and projection-specific anatomical analysis to examine the organization of this critical homeostatic circuit that regulates feeding. We show that AGRP neuronal circuits use a segregated, parallel, and redundant output configuration. AGRP neuron axon projections that target different brain regions originate from distinct subpopulations, several of which are sufficient to independently evoke feeding. The concerted anatomical and functional analysis of AGRP neuron projection populations reveals a constellation of core forebrain nodes, which are part of an extended circuit that mediates feeding behavior.

  17. Redundant and synergistic information transfer in cardiovascular and cardiorespiratory variability.

    PubMed

    Faes, Luca; Porta, Alberto; Nollo, Giandomenico

    2015-08-01

    In the framework of information dynamics, new tools are emerging which allow one to quantify how the information provided by two source processes about a target process results from the contribution of each source and from the interaction between the sources. We present the first implementation of these tools in the assessment of short-term cardiovascular and cardiorespiratory variability, by introducing two strategies for the decomposition of the information transferred to heart period (HP) variability from systolic arterial pressure (SAP) and respiration flow (RF) variability. Several measures based on the notion of transfer entropy (TE) are defined to quantify joint, individual and redundant/synergistic information transfer, and are then estimated from the series of HP, SAP and RF obtained from healthy subjects during head-up tilt and paced breathing protocols. Our results show that the proposed information decomposition methods provide an enhanced view on cardiovascular and cardiorespiratory regulation.

  18. Evolution of shuttle avionics redundancy management/fault tolerance

    NASA Technical Reports Server (NTRS)

    Boykin, J. C.; Thibodeau, J. R.; Schneider, H. E.

    1985-01-01

    The challenge of providing redundancy management (RM) and fault tolerance to meet the Shuttle Program requirements of fail operational/fail safe for the avionics systems was complicated by the critical program constraints of weight, cost, and schedule. The basic and sometimes false effectivity of less than pure RM designs is addressed. Evolution of the multiple input selection filter (the heart of the RM function) is discussed with emphasis on the subtle interactions of the flight control system that were found to be potentially catastrophic. Several other general RM development problems are discussed, with particular emphasis on the inertial measurement unit RM, indicative of the complexity of managing that three string system and its critical interfaces with the guidance and control systems.

  19. Exploiting stoichiometric redundancies for computational efficiency and network reduction.

    PubMed

    Ingalls, Brian P; Bembenek, Eric

    2015-01-01

    Analysis of metabolic networks typically begins with construction of the stoichiometry matrix, which characterizes the network topology. This matrix provides, via the balance equation, a description of the potential steady-state flow distribution. This paper begins with the observation that the balance equation depends only on the structure of linear redundancies in the network, and so can be stated in a succinct manner, leading to computational efficiencies in steady-state analysis. This alternative description of steady-state behaviour is then used to provide a novel method for network reduction, which complements existing algorithms for describing intracellular networks in terms of input-output macro-reactions (to facilitate bioprocess optimization and control). Finally, it is demonstrated that this novel reduction method can be used to address elementary mode analysis of large networks: the modes supported by a reduced network can capture the input-output modes of a metabolic module with significantly reduced computational effort. PMID:25547516

  20. Survivable algorithms and redundancy management in NASA's distributed computing systems

    NASA Technical Reports Server (NTRS)

    Malek, Miroslaw

    1992-01-01

    The design of survivable algorithms requires a solid foundation for executing them. While hardware techniques for fault-tolerant computing are relatively well understood, fault-tolerant operating systems, as well as fault-tolerant applications (survivable algorithms), are, by contrast, little understood, and much more work in this field is required. We outline some of our work that contributes to the foundation of ultrareliable operating systems and fault-tolerant algorithm design. We introduce our consensus-based framework for fault-tolerant system design. This is followed by a description of a hierarchical partitioning method for efficient consensus. A scheduler for redundancy management is introduced, and application-specific fault tolerance is described. We give an overview of our hybrid algorithm technique, which is an alternative to the formal approach given.

  1. Coded aperture imaging - Predicted performance of uniformly redundant arrays

    NASA Technical Reports Server (NTRS)

    Fenimore, E. E.

    1978-01-01

    It is noted that uniformly redundant arrays (URAs) have autocorrelation functions with perfectly flat sidelobes. A generalized signal-to-noise equation has been developed to predict URA performance. The signal-to-noise value is formulated as a function of aperture transmission or density, the ratio of the intensity of a resolution element to the integrated source intensity, and the ratio of detector background noise to the integrated intensity. It is shown that the only two-dimensional URAs known have a transmission of one half. This is not a great limitation because a nonoptimum transmission of one half never reduces the signal-to-noise ratio more than 30%. The reconstructed URA image contains practically uniform noise, regardless of the object structure. URA's improvement over the single-pinhole camera is much larger for high-intensity points than for low-intensity points.

  2. Self-locking double retention redundant full pin release

    NASA Technical Reports Server (NTRS)

    Killgrove, T. O. (Inventor)

    1985-01-01

    A double retention redundant pull pin release system is disclosed. The system responds to a single pull during an intentional release operation. A spiral threaded main pin is seated in a mating bore in a housing, which main pin has a flange fastened thereon at the part of the main pin which is exterior to the housing. Accidental release tends to rotate the main pin. A secondary pin passes through a slightly oversized opening in the flange and is seated in a second bore in the housing. The pins counteract against one another to prevent accidential release. A frictional lock is shared between the main and secondary pins to enhance further locking of the system. The secondary pin, in response to a first pull, is fully retracted from its bore and flange hole. Thereafter the pull causes the main pin to rotate free of the housing to release, for example, a parachute mechanism.

  3. Self-locking double retention redundant pull pin release

    NASA Technical Reports Server (NTRS)

    Killgrove, Thomas O. (Inventor)

    1987-01-01

    A double-retention redundant pull pin release system is disclosed. The system responds to a single pull during an intentional release operation. A spiral-threaded main pin is seated in a mating bore in a housing, which main pin has a flange fastened thereon at the part of the main pin which is exterior to the housing. Accidental release tends to rotate the main pin. A secondary pin passes through a slightly oversized opening in the flange and is seated in a second bore in the housing. The pins counteract against one another to prevent accidental release. A frictional lock is shared between the main and secondary pins to enhance further locking of the system. The secondary pin, in response to a first pull, is fully retracted from its bore and flange hole. Thereafter the pull causes the main pin to rotate free of the housing to release, for example, a parachute mechanism.

  4. Fuzzy logic for elimination of redundant information of microarray data.

    PubMed

    Huerta, Edmundo Bonilla; Duval, Béatrice; Hao, Jin-Kao

    2008-06-01

    Gene subset selection is essential for classification and analysis of microarray data. However, gene selection is known to be a very difficult task since gene expression data not only have high dimensionalities, but also contain redundant information and noises. To cope with these difficulties, this paper introduces a fuzzy logic based pre-processing approach composed of two main steps. First, we use fuzzy inference rules to transform the gene expression levels of a given dataset into fuzzy values. Then we apply a similarity relation to these fuzzy values to define fuzzy equivalence groups, each group containing strongly similar genes. Dimension reduction is achieved by considering for each group of similar genes a single representative based on mutual information. To assess the usefulness of this approach, extensive experimentations were carried out on three well-known public datasets with a combined classification model using three statistic filters and three classifiers. PMID:18973862

  5. Non-redundant Masking (NRM) on JWST FGS-TFI

    NASA Astrophysics Data System (ADS)

    Sivaramakrishnan, Anand; Tuthill, P.; Ireland, M.; Lloyd, J.; Martinashe, F.; Soummer, R.; Makidon, R.

    2009-01-01

    The 7-hole non-redundant mask in FGS-TFI will deliver at least 10 magnitudes of dynamic range between 0.1 and 0.4 arcsec at 3.8 um and longer wavelengths, using routine target acquisition, observing sequences, and pipeline data calibraton. This places protoplanets in Taurus within JWST's purview, opening up a search space inaccessible to JWST coronagraphs and future 30-m extremely large telescopes, especially in the mid-IR. NRM will also enable milliarcsecond astrometry on JWST. On the ground NRM mitigates speckle noise. On JWST it will deliver unsurpassed contrast while reducing JWST mission risk induced by the telescope's segmented, deployable primary mirror and wavefront sensing schemes. NRM will image the vicinity of an M=7 star in 10ks, meshing with next-generation extreme adaptive optics coronagraphs. Targets as bright as M=3 will also be observable with NRM on JWST.

  6. Efficient Switching Arrangement for (N + 1)/N Redundancy

    NASA Technical Reports Server (NTRS)

    Lux, James; McMaster, Robert

    2007-01-01

    An efficient arrangement of four switches has been conceived for coupling, to four output ports, the output powers of any subset of four devices that are members of a redundant set of five devices. In normal operation, the output power of each of four of the devices would be coupled to one of the four output ports. The remaining device would be kept as a spare: normally, its output power would be coupled to a load, wherein that power would be dissipated. In the event of failure of one of the four normally used devices, that device would be disconnected from its output port and connected to the load, and the spare device would be connected to the output from which the failed device was disconnected. Alternatively or in addition, the outputs of one or more devices could be sent to ports other than the ones originally assigned to them.

  7. Exploiting stoichiometric redundancies for computational efficiency and network reduction

    PubMed Central

    Ingalls, Brian P.; Bembenek, Eric

    2015-01-01

    Abstract Analysis of metabolic networks typically begins with construction of the stoichiometry matrix, which characterizes the network topology. This matrix provides, via the balance equation, a description of the potential steady-state flow distribution. This paper begins with the observation that the balance equation depends only on the structure of linear redundancies in the network, and so can be stated in a succinct manner, leading to computational efficiencies in steady-state analysis. This alternative description of steady-state behaviour is then used to provide a novel method for network reduction, which complements existing algorithms for describing intracellular networks in terms of input-output macro-reactions (to facilitate bioprocess optimization and control). Finally, it is demonstrated that this novel reduction method can be used to address elementary mode analysis of large networks: the modes supported by a reduced network can capture the input-output modes of a metabolic module with significantly reduced computational effort. PMID:25547516

  8. Complementarity and redundancy of IL-22-producing innate lymphoid cells

    PubMed Central

    Rankin, Lucille C.; Girard-Madoux, Mathilde J. H.; Seillet, Cyril; Mielke, Lisa A.; Kerdiles, Yann; Fenis, Aurore; Wieduwild, Elisabeth; Putoczki, Tracy; Mondot, Stanislas; Lantz, Olivier; Demon, Dieter; Papenfuss, Anthony T.; Smyth, Gordon K.; Lamkanfi, Mohamed; Carotta, Sebastian; Renauld, Jean-Christophe; Shi, Wei; Carpentier, Sabrina; Soos, Tim; Arendt, Christopher; Ugolini, Sophie; Huntington, Nicholas D.; Belz, Gabrielle T.; Vivier, Eric

    2015-01-01

    Intestinal T cells and group 3 innate lymphoid cells (ILC3) control the composition of the microbiota and gut immune responses. Within the gut there coexists ILC3 subsets which either express or lack the Natural cytoxicity receptor (NCR) NKp46. We identify here the transcriptional signature associated with the T-bet-dependent differentiation of NCR− ILC3 into NCR+ ILC3. Contrary to the prevailing view, we show by conditional deletion of the key ILC3 genes Stat3, Il22, Tbx21 and Mcl1 that NCR+ ILC3 were redundant for the control of mouse colonic infections with Citrobacter rodentium in the presence of T cells. However, NCR+ ILC3 were essential for cecum homeostasis. Our data show that interplay between intestinal ILC3 and adaptive lymphocytes results in robust complementary fail-safe mechanisms ensuring gut homeostasis. PMID:26595889

  9. The non-redundant Bacillus subtilis (NRSub) database: update 1998.

    PubMed

    Perrière, G; Gouy, M; Gojobori, T

    1998-01-01

    The non-redundant Bacillus subtilis database (NRSub) has been developed in the context of the sequencing project devoted to this bacterium. As this project has reached completion, the whole genome is now available as a single contig. Thanks to the ACNUC database management system and its associated retrieval system Query_win, each functional region of the genome can be accessed individually. Extra annotations have been added such as accession numbers for the genes, locations on the genetic map, codon adaptation index values, as well as cross-references with other collections. NRSub is distributed through anonymous FTP as a text file in EMBL format and as an ACNUC database. It is also possible to access NRSub through two dedicated World Wide Web servers located in France (http://acnuc. univ-lyon1.fr/nrsub/nrsub.html ) and in Japan (http://ddbjs4h.genes. nig.ac.jp/ ). PMID:9399801

  10. Ground and flight test experience with a triple redundant digital fly by wire control system. [installed in F-8C aircraft

    NASA Technical Reports Server (NTRS)

    Jarvis, C. R.; Szalai, K. J.

    1981-01-01

    A triplex digital fly by wire flight control system was developed and installed in an F-8C aircraft to provide fail operative, full authority control. Hardware and software redundancy management techniques were designed to detect and identify failures in the system. Control functions typical of those projected for future actively controlled vehicles were implemented.

  11. Using Redundancy To Reduce Errors in Magnetometer Readings

    NASA Technical Reports Server (NTRS)

    Kulikov, Igor; Zak, Michail

    2004-01-01

    A method of reducing errors in noisy magnetic-field measurements involves exploitation of redundancy in the readings of multiple magnetometers in a cluster. By "redundancy"is meant that the readings are not entirely independent of each other because the relationships among the magnetic-field components that one seeks to measure are governed by the fundamental laws of electromagnetism as expressed by Maxwell's equations. Assuming that the magnetometers are located outside a magnetic material, that the magnetic field is steady or quasi-steady, and that there are no electric currents flowing in or near the magnetometers, the applicable Maxwell 's equations are delta x B = 0 and delta(raised dot) B = 0, where B is the magnetic-flux-density vector. By suitable algebraic manipulation, these equations can be shown to impose three independent constraints on the values of the components of B at the various magnetometer positions. In general, the problem of reducing the errors in noisy measurements is one of finding a set of corrected values that minimize an error function. In the present method, the error function is formulated as (1) the sum of squares of the differences between the corrected and noisy measurement values plus (2) a sum of three terms, each comprising the product of a Lagrange multiplier and one of the three constraints. The partial derivatives of the error function with respect to the corrected magnetic-field component values and the Lagrange multipliers are set equal to zero, leading to a set of equations that can be put into matrix.vector form. The matrix can be inverted to solve for a vector that comprises the corrected magnetic-field component values and the Lagrange multipliers.

  12. Intrinsic Toxicity of Unchecked Heterochromatin Spread Is Suppressed by Redundant Chromatin Boundary Functions in Schizosacchromyces pombe.

    PubMed

    Garcia, Jennifer F; Al-Sady, Bassem; Madhani, Hiten D

    2015-07-01

    Effective boundary mechanisms halt the spread of repressive histone methylation. In the fission yeast Schizosacchromyces pombe, two factors/elements required for boundary function have been described, the jmjC protein Epe1 and binding sites for the RNA polymerase III transcription factor TFIIIC. Perplexingly, individual mutation of Epe1 or TFIIIC sites produces only mild boundary defects, and no other boundary factors have been identified. To approach these issues, we developed a synthetic reporter gene tool that uses a tethered Clr4 histone H3K9 methyltransferase and monitors the ability of a DNA element to block heterochromatin spread. The inverted repeat (IR) that flanks the mat2/3 silent mating-type cassette region demonstrates strong boundary activity compared to sequences that flank pericentromeric heterochromatic repeats. Rather than acting in the same inhibitory pathway, Epe1 and TFIIIC sites mediate boundary function of the IR via the two parallel and largely redundant pathways. We also use the system to demonstrate that HP1/Swi6 promotes boundary activity in addition to promoting silencing and acts in the same pathway as Epe1. Inhibition of heterochromatin spread at the endogenous IR element also requires either Epe1 or TFIIIC sites. Strikingly, mutation of both mechanisms results in growth inhibition that is associated with the spread of heterochromatin over many kilobases to the nearest essential gene and the near-complete silencing of several intervening euchromatic genes. The growth defect is reversed by deletion of clr4+, indicating that the redundant boundary mechanisms protect cells from intrinsic toxicity caused by the spread of heterochromatin.

  13. ERK1 and ERK2 Map Kinases: Specific Roles or Functional Redundancy?

    PubMed Central

    Buscà, Roser; Pouysségur, Jacques; Lenormand, Philippe

    2016-01-01

    The MAP kinase signaling cascade Ras/Raf/MEK/ERK has been involved in a large variety of cellular and physiological processes that are crucial for life. Many pathological situations have been associated to this pathway. More than one isoform has been described at each level of the cascade. In this review we devoted our attention to ERK1 and ERK2, which are the effector kinases of the pathway. Whether ERK1 and ERK2 specify functional differences or are in contrast functionally redundant, constitutes an ongoing debate despite the huge amount of studies performed to date. In this review we compiled data on ERK1 vs. ERK2 gene structures, protein sequences, expression levels, structural and molecular mechanisms of activation and substrate recognition. We have also attempted to perform a rigorous analysis of studies regarding the individual roles of ERK1 and ERK2 by the means of morpholinos, siRNA, and shRNA silencing as well as gene disruption or gene replacement in mice. Finally, we comment on a recent study of gene and protein evolution of ERK isoforms as a distinct approach to address the same question. Our review permits the evaluation of the relevance of published studies in the field especially when measurements of global ERK activation are taken into account. Our analysis favors the hypothesis of ERK1 and ERK2 exhibiting functional redundancy and points to the concept of the global ERK quantity, and not isoform specificity, as being the essential determinant to achieve ERK function. PMID:27376062

  14. Two-phase functional redundancy in plant communities along a grazing gradient in Mongolian rangelands.

    PubMed

    Sasaki, Takehiro; Okubo, Satoru; Okayasu, Tomoo; Jamsran, Undarmaa; Ohkuro, Toshiya; Takeuchi, Kazuhiko

    2009-09-01

    The concept of functional redundancy is at the core of theory relating changes in ecosystem functioning to species loss. However, few empirical studies have investigated the strength and form of the relationship between species and functional diversity (i.e., the presence of functional redundancy in ecological communities) in this context. In particular, we know little about how local extinctions in real communities might impact functional diversity. Here, we examined the relationship between species and functional diversity in plant communities along a grazing gradient across Mongolian rangeland ecosystems. We applied a recently described measure of functional diversity that incorporates species' dissimilarities defined from plant functional traits and tested several hypothesized forms of the relationship between species and functional diversity using linear and nonlinear modeling techniques. We found a significant sigmoid logistic relationship between species richness and functional diversity in relatively benign environmental conditions. This indicates high functional redundancy at low levels of species richness followed by a rapid increase at intermediate levels, until functional diversity reaches an asymptote at high levels (i.e., two-phase functional redundancy). In contrast, we generally observed a positive linear relationship between these parameters in relatively harsh environmental conditions, indicating low functional redundancy. Observed functional redundancy probably resulted from two factors, intrinsic redundancy in species' functional traits and extrinsic redundancy caused by nonrandom compositional change that is nonrandom with respect to functional traits. Lack of either intrinsic or extrinsic redundancy may result in low functional redundancy. Two-phase functional redundancy suggests that functional traits are abruptly lost from a community below a certain level of species richness, and a community then shifts into a contrasting state that has a

  15. Blue light regulated shade avoidance.

    PubMed

    Keuskamp, Diederik H; Keller, Mercedes M; Ballaré, Carlos L; Pierik, Ronald

    2012-04-01

    Most plants grow in dense vegetation with the risk of being out-competed by neighboring plants. These neighbors can be detected not only through the depletion in light quantity that they cause, but also through the change in light quality, which plants perceive using specific photoreceptors. Both the reduction of the red:far-red ratio and the depletion of blue light are signals that induce a set of phenotypic traits, such as shoot elongation and leaf hyponasty, which increase the likelihood of light capture in dense plant stands. This set of phenotypic responses are part of the so called shade avoidance syndrome (SAS). This addendum discusses recent findings on the regulation of the SAS of Arabidopsis thaliana upon blue light depletion. Keller et al. and Keuskamp et al. show that the low blue light attenuation induced shade avoidance response of seedling and rosette-stage A. thaliana plants differ in their hormonal regulation. These studies also show there is a regulatory overlap with the R:FR-regulated SAS.

  16. Angiotensin II disrupts inhibitory avoidance memory retrieval.

    PubMed

    Bonini, Juliana S; Bevilaqua, Lia R; Zinn, Carolina G; Kerr, Daniel S; Medina, Jorge H; Izquierdo, Iván; Cammarota, Martín

    2006-08-01

    The brain renin-angiotensin system (RAS) is involved in learning and memory, but the actual role of angiotensin II (A(II)) and its metabolites in this process has been difficult to comprehend. This has been so mainly due to procedural issues, especially the use of multi-trial learning paradigms and the utilization of pre-training intracerebroventricular infusion of RAS-acting compounds. Here, we specifically analyzed the action of A(II) in aversive memory retrieval using a hippocampal-dependent, one-trial, step-down inhibitory avoidance task (IA) in combination with stereotaxically localized intrahippocampal infusion of drugs. Rats bilaterally implanted with infusion cannulae aimed to the CA1 region of the dorsal hippocampus were trained in IA and tested for memory retention 24 h later. We found that when given into CA1 15 min before IA memory retention test, A(II), but not angiotensin IV or angiotensin(1-7) induced a dose-dependent and reversible amnesia without altering locomotor activity, exploratory behavior or anxiety state. The effect of A(II) was blocked in a dose-dependent manner by the A(II)-type 2 receptor (AT(2)) antagonist PD123319 but not by the A(II)-type 1 receptor (AT(1)) antagonist losartan. By themselves, neither PD123319 nor losartan had any effect on memory expression. Our data indicate that intra-CA1 A(II) hinders retrieval of avoidance memory through a process that involves activation of AT(2) receptors.

  17. Redundancy in Foreign Language Reading Comprehension Instruction: Concurrent Written and Spoken Presentations

    ERIC Educational Resources Information Center

    Diao, Yali; Sweller, John

    2007-01-01

    In an example of the redundancy effect, learning is inhibited when written and spoken text containing the same information is presented simultaneously rather than in written or spoken form alone. The current research was designed to investigate whether the redundancy effect applied to reading comprehension in English as a foreign language (EFL) by…

  18. The Redundancy of Mathematics Instruction in U.S. Elementary and Middle Schools

    ERIC Educational Resources Information Center

    Polikoff, Morgan S.

    2012-01-01

    International comparisons have highlighted that the U.S. mathematics curriculum, both in terms of curriculum influences (e.g., textbooks, standards) and actual instruction, is broad and shallow. Standards-based reform is explicitly designed to improve coherence and reduce redundancy across grades. This article evaluates the redundancy of…

  19. Redundancy, Relevance, and Value to the User in the Outputs of Information Retrieval Systems

    ERIC Educational Resources Information Center

    Cleverdon, C. W.; Kidd, J. S.

    1976-01-01

    A test was carried out to investigate the assumption that there is a significant level of redundancy between documents. The conclusions were that notional overlap exists, but there appear to be very few cases of extreme redundancy, and at the document level, there is little possibility of practical application. (Author)

  20. Infant Reactivity to Redundant Proprioceptive and Auditory Stimulation: A Twin Study.

    ERIC Educational Resources Information Center

    Van den Daele, Leland D.

    The role of genetic factors in infant response to redundancy was evaluated through observation of the behavior of three sets of same-sex fraternal twins and six sets of same-sex identical twins to combinations of redundant proprioceptive and auditory stimulation. The twins ranged in age from 6 weeks to 24 weeks. One member of each twin set was…

  1. 77 FR 28797 - Redundancy of Communications Systems: Backup Power Private Land Mobile Radio Services: Selection...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-16

    ... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS COMMISSION 47 CFR Parts 12 and 90 Redundancy of Communications Systems: Backup Power Private Land Mobile...--REDUNDANCY OF COMMUNICATIONS SYSTEMS 0 1. The authority citation for part 12 continues to read as...

  2. Repetitive, duplicate, and redundant publications: a review for authors and readers.

    PubMed

    Johnson, Claire

    2006-09-01

    Repetitive, duplicate, and redundant publications are an important concern in the scientific literature. Their occurrence affects science and carries with it sanctions of consequence. This editorial provides a brief review of the definitions, classifications, impact, sanctions, and prevention strategies regarding repetitive, duplicate, and redundant publications.

  3. Three Design Principles of Language: The Search for Parsimony in Redundancy

    ERIC Educational Resources Information Center

    Beekhuizen, Barend; Bod, Rens; Zuidema, Willem

    2013-01-01

    In this paper we present three design principles of language--experience, heterogeneity and redundancy--and present recent developments in a family of models incorporating them, namely Data-Oriented Parsing/Unsupervised Data-Oriented Parsing. Although the idea of some form of redundant storage has become part and parcel of parsing technologies and…

  4. The Problem of Empirical Redundancy of Constructs in Organizational Research: An Empirical Investigation

    ERIC Educational Resources Information Center

    Le, Huy; Schmidt, Frank L.; Harter, James K.; Lauver, Kristy J.

    2010-01-01

    Construct empirical redundancy may be a major problem in organizational research today. In this paper, we explain and empirically illustrate a method for investigating this potential problem. We applied the method to examine the empirical redundancy of job satisfaction (JS) and organizational commitment (OC), two well-established organizational…

  5. Exploring the Redundancy Effect in Print-Based Instruction Containing Representations

    ERIC Educational Resources Information Center

    Morrison, Jennifer; Watson, Ginger S.; Morrison, Gary R.

    2015-01-01

    The purpose of this study was to evaluate the effects of redundancy when learning from realistic science materials. Participants received instruction where redundancy was manipulated between text and diagrams with captions, text and diagrams, and text only. Participants reported levels of cognitive load, responded to questionnaire items and…

  6. Testing the Race Model Inequality in Redundant Stimuli with Variable Onset Asynchrony

    ERIC Educational Resources Information Center

    Gondan, Matthias

    2009-01-01

    In speeded response tasks with redundant signals, parallel processing of the signals is tested by the race model inequality. This inequality states that given a race of two signals, the cumulative distribution of response times for redundant stimuli never exceeds the sum of the cumulative distributions of response times for the single-modality…

  7. Perforant pathway stimulation as a conditioned stimulus for active avoidance learning triggers BOLD responses in various target regions of the hippocampus: a combined fMRI and electrophysiological study.

    PubMed

    Angenstein, Frank; Krautwald, Karla; Wetzel, Wolfram; Scheich, Henning

    2013-07-15

    Functional magnetic resonance imaging and electrophysiology were combined to monitor blood oxygen level dependent (BOLD) signals in the entire rat brain and neuronal activities in the dentate gyrus during electrical stimulation of the right perforant pathway. In naïve, medetomidine sedated animals, stimulation of the fiber bundle with 15 trains (i.e. 8 bursts of 20 pulses given with 10 ms intervals, one burst per second, pulse width 0.2 ms) generated significant BOLD responses in the right hippocampal formation and the left entorhinal cortex. The stimulation condition also caused changes in the synaptic efficacy of perforant pathway granular cell synapses that lasted for at least one day. Rerun of the same experiment one day later resulted in a significantly increased electrophysiological response in the dentate gyrus and an increase of the BOLD response in the entire hippocampal formation. Consequently, long-lasting changes in synaptic efficacy go along with changes in the generated BOLD response. Additional electrical stimulations of the perforant pathway in the awake animal between the two fMRI experiments caused in the second fMRI measurement an increased BOLD response in the hippocampal formation and an appearance of significant BOLD responses in target regions of the hippocampus, such as the septum, nucleus accumbens (NAcc), and anterior cingulate cortex/medial prefrontal cortex/motor cortex (ACC/mPFC/MC) regions. Consequently, the efficacy of signal processing in and propagation through the hippocampus can be monitored by variations of the BOLD response in target regions of the hippocampus. Using the electrical perforant pathway stimulations as conditioned stimulus for an active avoidance task (shuttle box) caused a further spreading of the BOLD response in the hippocampus formation, septum and ACC/mPFC/MC but not in the NAcc. In addition, the magnitude of the BOLD response in the trained animals was further increased in the right and left hippocampus and

  8. Osteonecrosis: avoiding total hip arthroplasty.

    PubMed

    Hungerford, David S

    2002-06-01

    Osteonecrosis of the femoral head afflicts approximately 20,000 new patients per year, at an average age of 38. Of the patients seen in our institution, 25% are <25 years old. Without treatment, most of these patients can be expected to need a total hip arthroplasty. Joint-preserving procedures have a significant failure rate, and some have significant morbidity. It is desirable to avoid or delay total hip arthroplasty because most patients with osteonecrosis outlive the current state-of-the-art prostheses. Four issues need to be weighed to arrive at a reasonable algorithm for the preservative treatment of osteonecrosis: i) patient risk factors, ii) morbidity of the proposed procedure, iii) size of the lesion, and iv) stage of the lesion. All of the issues must be considered to make sense out of a complex clinical situation.

  9. Autonomous hazard detection and avoidance

    NASA Technical Reports Server (NTRS)

    Pien, Homer

    1992-01-01

    During GFY 91, Draper Laboratory was awarded a task by NASA-JSC under contract number NAS9-18426 to study and evaluate the potential for achieving safe autonomous landings on Mars using an on-board autonomous hazard detection and avoidance (AHDA) system. This report describes the results of that study. The AHDA task had four objectives: to demonstrate, via a closed-loop simulation, the ability to autonomously select safe landing sites and the ability to maneuver to the selected site; to identify key issues in the development of AHDA systems; to produce strawman designs for AHDA sensors and algorithms; and to perform initial trade studies leading to better understanding of the effect of sensor/terrain/viewing parameters on AHDA algorithm performance. This report summarizes the progress made during the first year, with primary emphasis on describing the tools developed for simulating a closed-loop AHDA landing. Some cursory performance evaluation results are also presented.

  10. eWasted time: Redundant work during hospital admission and discharge.

    PubMed

    MacMillan, Thomas E; Slessarev, Marat; Etchells, Edward

    2016-03-01

    Potential unintended consequences of health information technology include fragmentation of workflow and redundant work. We could not identify any prior direct observation studies that quantified redundant work related to health information technology in the clinical setting. Our objective was to quantify redundant work during admission and discharge to our general internal medicine service at an academic medical center. We performed a time and motion study at Sunnybrook Health Sciences Centre in Toronto, Canada. We observed 13 clinicians performing an admission or a discharge, and the type and length of each task was recorded using an Apple iPad tablet. We identified redundant tasks related to health information technology and calculated the time spent completing these tasks. We found that 22 percent of clinician time was spent on redundant tasks. Our finding highlights the importance of workflow and software integration when implementing health information technology.

  11. Management of redundancy in flight control systems using optimal decision theory

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The problem of using redundancy that exists between dissimilar systems in aircraft flight control is addressed. That is, using the redundancy that exists between a rate gyro and an accelerometer--devices that have dissimilar outputs which are related only through the dynamics of the aircraft motion. Management of this type of redundancy requires advanced logic so that the system can monitor failure status and can reconfigure itself in the event of one or more failures. An optimal decision theory was tutorially developed for the management of sensor redundancy and the theory is applied to two aircraft examples. The first example is the space shuttle and the second is a highly maneuvering high performance aircraft--the F8-C. The examples illustrate the redundancy management design process and the performance of the algorithms presented in failure detection and control law reconfiguration.

  12. A cuckoo search algorithm by Lévy flights for solving reliability redundancy allocation problems

    NASA Astrophysics Data System (ADS)

    Valian, Ehsan; Valian, Elham

    2013-11-01

    A new metaheuristic optimization algorithm, called cuckoo search (CS), was recently developed by Yang and Deb (2009, 2010). This article uses CS and Lévy flights to solve the reliability redundancy allocation problem. The redundancy allocation problem involves setting reliability objectives for components or subsystems in order to meet the resource consumption constraint, e.g. the total cost. The difficulties facing the redundancy allocation problem are to maintain feasibility with respect to three nonlinear constraints, namely, cost, weight and volume-related constraints. The redundancy allocation problems have been studied in the literature for decades, usually using mathematical programming or metaheuristic optimization algorithms. The performance of the algorithm is tested on five well-known reliability redundancy allocation problems and is compared with several well-known methods. Simulation results demonstrate that the optimal solutions obtained by CS are better than the best solutions obtained by other methods.

  13. Study of techniques for redundancy verification without disrupting systems, phases 1-3

    NASA Technical Reports Server (NTRS)

    1970-01-01

    The problem of verifying the operational integrity of redundant equipment and the impact of a requirement for verification on such equipment are considered. Redundant circuits are examined and the characteristics which determine adaptability to verification are identified. Mutually exclusive and exhaustive categories for verification approaches are established. The range of applicability of these techniques is defined in terms of signal characteristics and redundancy features. Verification approaches are discussed and a methodology for the design of redundancy verification is developed. A case study is presented which involves the design of a verification system for a hypothetical communications system. Design criteria for redundant equipment are presented. Recommendations for the development of technological areas pertinent to the goal of increased verification capabilities are given.

  14. NASA satellite helps airliners avoid ozone concentrations

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Results from a test to determine the effectiveness of satellite data for helping airlines avoid heavy concentrations of ozone are reported. Information from the Total Ozone Mapping Spectrometer, aboard the Nimbus-7 was transmitted, for use in meteorological forecast activities. The results show: (1) Total Ozone Mapping Spectrometer profile of total ozone in the atmosphere accurately represents upper air patterns and can be used to locate meteorological activity; (2) route forecasting of highly concentrated ozone is feasible; (3) five research aircraft flights were flown in jet stream regions located by the Total Ozone Mapping Spectrometer to determine winds, temperatures, and air composition. It is shown that the jet stream is coincides with the area of highest total ozone gradient, and low total ozone amounts are found where tropospheric air has been carried along above the tropopause on the anticyclonic side of the subtropical jet stream.

  15. Top2 and Sgs1-Top3 Act Redundantly to Ensure rDNA Replication Termination

    PubMed Central

    Fredsøe, Jacob; Nielsen, Ida; Pedersen, Jakob Madsen; Bentsen, Iben Bach; Lisby, Michael; Bjergbaek, Lotte; Andersen, Anni H

    2015-01-01

    Faithful DNA replication with correct termination is essential for genome stability and transmission of genetic information. Here we have investigated the potential roles of Topoisomerase II (Top2) and the RecQ helicase Sgs1 during late stages of replication. We find that cells lacking Top2 and Sgs1 (or Top3) display two different characteristics during late S/G2 phase, checkpoint activation and accumulation of asymmetric X-structures, which are both independent of homologous recombination. Our data demonstrate that checkpoint activation is caused by a DNA structure formed at the strongest rDNA replication fork barrier (RFB) during replication termination, and consistently, checkpoint activation is dependent on the RFB binding protein, Fob1. In contrast, asymmetric X-structures are formed independent of Fob1 at less strong rDNA replication fork barriers. However, both checkpoint activation and formation of asymmetric X-structures are sensitive to conditions, which facilitate fork merging and progression of replication forks through replication fork barriers. Our data are consistent with a redundant role of Top2 and Sgs1 together with Top3 (Sgs1-Top3) in replication fork merging at rDNA barriers. At RFB either Top2 or Sgs1-Top3 is essential to prevent formation of a checkpoint activating DNA structure during termination, but at less strong rDNA barriers absence of the enzymes merely delays replication fork merging, causing an accumulation of asymmetric termination structures, which are solved over time. PMID:26630413

  16. MEMS-based redundancy ring for low-noise millimeter-wave front-end

    NASA Astrophysics Data System (ADS)

    Pons, Patrick; Dubuc, David; Flourens, Federic; Saddaoui, Mohammad; Melle, Samuel; Tackacs, Alex; Tao, Junwu; Aubert, Herve; Boukabache, Ali; Paillot, T.; Blondy, Pierre; Vendier, Olivier; Grenier, Katia M.; Plana, Robert

    2004-08-01

    This paper reports on the investigation of the potentialities of the MEMS technologies to develop innovative microsystem for millimetre wave communication essentially for space applications. One main issue deals with the robustness and the reliability of the equipment as it may difficult to replace or to repair them when a satellite has been launched. One solution deals with the development of redundancy rings that are making the front end more robust. Usually, the architecture of such system involves waveguide or diode technologies, which present severe limitations in term of weight, volume and insertion loss. The concept considered in this paper is to replace some key elements of such system by MEMS based devices (Micromachined transmission lines, switches) in order to optimize both the weight and the microwave performance of the module. A specific technological process has been developed consisting in the fabrication of the devices on a dielectric membrane on air suspended in order to improve the insertion loss and the isolation. To prove the concept, building blocks have been already fabricated and measured (i.e micromachined transmission and filter featuring very low insertion loss, single pole double through circuits to address the appropriate path of the redundancy ring). We have to outline that MEMS technology have allowed a simplification of the architecture and a different system partitioning which gives more degree of freedom for the system designer. Furthermore, it has been conducted an exhaustive reliability study in order to identify the failure mechanisms. Again, from the results obtained, we have proposed an original topology for the SPDT circuit that takes into account the reliability behaviour of the MEMS devices and that allow to prevent most of the failure mechanisms reported so far (mainly related to the dielectric charging effect). Finally, the active device (millimetre wave low noise amplifier) will be reported on the MEMS based chip using

  17. Signs of neutralization in a redundant gene involved in homologous recombination in Wolbachia endosymbionts.

    PubMed

    Badawi, Myriam; Giraud, Isabelle; Vavre, Fabrice; Grève, Pierre; Cordaux, Richard

    2014-09-17

    Genomic reduction in bacterial endosymbionts occurs through large genomic deletions and long-term accumulation of mutations. The latter process involves successive steps including gene neutralization, pseudogenization, and gradual erosion until complete loss. Although many examples of pseudogenes at various levels of degradation have been reported, neutralization cases are scarce because of the transient nature of the process. Gene neutralization may occur due to relaxation of selection in nonessential genes, for example, those involved in redundant functions. Here, we report an example of gene neutralization in the homologous recombination (HR) pathway of Wolbachia, a bacterial endosymbiont of arthropods and nematodes. The HR pathway is often depleted in endosymbiont genomes, but it is apparently intact in some Wolbachia strains. Analysis of 12 major HR genes showed that they have been globally under strong purifying selection during the evolution of Wolbachia strains hosted by arthropods, supporting the evolutionary importance of the HR pathway for these Wolbachia genomes. However, we detected signs of recent neutralization of the ruvA gene in a subset of Wolbachia strains, which might be related to an ancestral, clade-specific amino acid change that impaired DNA-binding activity. Strikingly, RuvA is part of the RuvAB complex involved in branch migration, whose function overlaps with the RecG helicase. Although ruvA is experiencing neutralization, recG is under strong purifying selection. Thus, our high phylogenetic resolution suggests that we identified a rare example of targeted neutralization of a gene involved in a redundant function in an endosymbiont genome.

  18. Signs of Neutralization in a Redundant Gene Involved in Homologous Recombination in Wolbachia Endosymbionts

    PubMed Central

    Badawi, Myriam; Giraud, Isabelle; Vavre, Fabrice; Grève, Pierre; Cordaux, Richard

    2014-01-01

    Genomic reduction in bacterial endosymbionts occurs through large genomic deletions and long-term accumulation of mutations. The latter process involves successive steps including gene neutralization, pseudogenization, and gradual erosion until complete loss. Although many examples of pseudogenes at various levels of degradation have been reported, neutralization cases are scarce because of the transient nature of the process. Gene neutralization may occur due to relaxation of selection in nonessential genes, for example, those involved in redundant functions. Here, we report an example of gene neutralization in the homologous recombination (HR) pathway of Wolbachia, a bacterial endosymbiont of arthropods and nematodes. The HR pathway is often depleted in endosymbiont genomes, but it is apparently intact in some Wolbachia strains. Analysis of 12 major HR genes showed that they have been globally under strong purifying selection during the evolution of Wolbachia strains hosted by arthropods, supporting the evolutionary importance of the HR pathway for these Wolbachia genomes. However, we detected signs of recent neutralization of the ruvA gene in a subset of Wolbachia strains, which might be related to an ancestral, clade-specific amino acid change that impaired DNA-binding activity. Strikingly, RuvA is part of the RuvAB complex involved in branch migration, whose function overlaps with the RecG helicase. Although ruvA is experiencing neutralization, recG is under strong purifying selection. Thus, our high phylogenetic resolution suggests that we identified a rare example of targeted neutralization of a gene involved in a redundant function in an endosymbiont genome. PMID:25230723

  19. Does Plant Species Richness Guarantee the Resilience of Local Medical Systems? A Perspective from Utilitarian Redundancy

    PubMed Central

    Santoro, Flávia Rosa

    2015-01-01

    Resilience is related to the ability of a system to adjust to disturbances. The Utilitarian Redundancy Model has emerged as a tool for investigating the resilience of local medical systems. The model determines the use of species richness for the same therapeutic function as a facilitator of the maintenance of these systems. However, predictions generated from this model have not yet been tested, and a lack of variables exists for deeper analyses of resilience. This study aims to address gaps in the Utilitarian Redundancy Model and to investigate the resilience of two medical systems in the Brazilian semi-arid zone. As a local illness is not always perceived in the same way that biomedicine recognizes, the term “therapeutic targets” is used for perceived illnesses. Semi-structured interviews with local experts were conducted using the free-listing technique to collect data on known medicinal plants, usage preferences, use of redundant species, characteristics of therapeutic targets, and the perceived severity for each target. Additionally, participatory workshops were conducted to determine the frequency of targets. The medical systems showed high species richness but low levels of species redundancy. However, if redundancy was present, it was the primary factor responsible for the maintenance of system functions. Species richness was positively associated with therapeutic target frequencies and negatively related to target severity. Moreover, information about redundant species seems to be largely idiosyncratic; this finding raises questions about the importance of redundancy for resilience. We stress the Utilitarian Redundancy Model as an interesting tool to be used in studies of resilience, but we emphasize that it must consider the distribution of redundancy in terms of the treatment of important illnesses and the sharing of information. This study has identified aspects of the higher and lower vulnerabilities of medical systems, adding variables that

  20. Does plant species richness guarantee the resilience of local medical systems? A perspective from utilitarian redundancy.

    PubMed

    Santoro, Flávia Rosa; Ferreira Júnior, Washington Soares; Araújo, Thiago Antônio de Souza; Ladio, Ana Haydée; Albuquerque, Ulysses Paulino

    2015-01-01

    Resilience is related to the ability of a system to adjust to disturbances. The Utilitarian Redundancy Model has emerged as a tool for investigating the resilience of local medical systems. The model determines the use of species richness for the same therapeutic function as a facilitator of the maintenance of these systems. However, predictions generated from this model have not yet been tested, and a lack of variables exists for deeper analyses of resilience. This study aims to address gaps in the Utilitarian Redundancy Model and to investigate the resilience of two medical systems in the Brazilian semi-arid zone. As a local illness is not always perceived in the same way that biomedicine recognizes, the term "therapeutic targets" is used for perceived illnesses. Semi-structured interviews with local experts were conducted using the free-listing technique to collect data on known medicinal plants, usage preferences, use of redundant species, characteristics of therapeutic targets, and the perceived severity for each target. Additionally, participatory workshops were conducted to determine the frequency of targets. The medical systems showed high species richness but low levels of species redundancy. However, if redundancy was present, it was the primary factor responsible for the maintenance of system functions. Species richness was positively associated with therapeutic target frequencies and negatively related to target severity. Moreover, information about redundant species seems to be largely idiosyncratic; this finding raises questions about the importance of redundancy for resilience. We stress the Utilitarian Redundancy Model as an interesting tool to be used in studies of resilience, but we emphasize that it must consider the distribution of redundancy in terms of the treatment of important illnesses and the sharing of information. This study has identified aspects of the higher and lower vulnerabilities of medical systems, adding variables that should be