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Sample records for feedback lc-dfb ridge

  1. CW Performance of an InGaAs-GaAs-AlGaAs Laterally-Coupled Distributed Feedback (LC-DFB) Ridge Laser Diode

    NASA Technical Reports Server (NTRS)

    Martin, R. D.; Forouhar, S.; Keo, S.; Lang, R. J.; Hunsperger, R. G.; Tiberio, R. C.; Chapman, P. F.

    1995-01-01

    Single-mode distributed feedback (DFB) laser diodes typically require a two-step epitaxial growth or use of a corrugated substrate. We demonstrate InGaAs-GaAs-AlGaAs DFB lasers fabricated from a single epitaxial growth using lateral evanescent coupling of the optical field to a surface grating etehed along the sides of the ridge. A CW threshold current of 25 mA and external quantum efficiency of 0.48 mW/mA per facet were measured for a 1 mm cavity length device with anti-reflection coated facets. Single-mode output powers as high as 11 mW per facet at 935 nm wavelength were attained. A coupling coefficient of at least 5.8/cm was calculated from the subthreshold spectrum taking into account the 2% residual facet reflectivity.

  2. Fabrication-tolerant 1310 nm laterally-coupled distributed feedback lasers with high side mode suppression ratios

    SciTech Connect

    Millett, R.; Dridi, K.; Benhsaien, A.; Schriemer, H.; Hinzer, K.; Hall, T.

    2010-11-10

    A laterally-coupled distributed feedback (LC-DFB) laser was designed and fabricated using stepper lithography. Such DFB lasers eliminate the need of the commonly required re-growth steps in a conventional DFB laser fabrication process. With LC-DFB lasers, the grating can be lithographically patterned out of the ridge waveguide. High order gratings can enhance the lithographic tolerance for lower resolution patterning, yielding lasers more amenable to mass-manufacturing. 1310 nm InGaAsP/InP LC-DFB laser with third-order gratings was fabricated using i-line 5x stepper lithography. Excellent side mode suppression ratio over 52 dB has been measured with a single mode lasing around 1310 nm.

  3. Multi-electrode laterally coupled distributed feedback InGaAsP/InP lasers: a prescription for longitudinal mode control

    NASA Astrophysics Data System (ADS)

    Benhsaien, Abdessamad; Dridi, Kais; Zhang, Jessica; Hall, Trevor J.

    2013-10-01

    Photonic Integrated Circuits (PICs) enable photons as data carriers at a very high speed. PIC market opportunities call for reduced wafer dimensions, power consumption and cost as well as enhanced reliability. The PIC technology development must cater for the latter relentless traits. In particular, monolithic PICs are sought as they can integrate hundreds of components and functions onto a single chip. InGaAsP/InP laterally-coupled distributed feedback (LC-DFB) lasers stand as key enablers in the PIC technology thanks to the compelling advantages their embedded high-order surface-gratings have. The patterning of the spatial corrugation along the sidewalls of the LC-DFB ridge, has been established to make the epitaxial overgrowth unnecessary thereby reducing the cost and time of manufacturing, and ultimately increasing the yield. LC-DFBs boast a small footprint synonymous of enhanced monolithic integrate-ability. Nonetheless, LC-DFBs suffer from the adverse longitudinal spatial hole burning (LSHB) effects materialized by typically quite high threshold current levels. Indeed, the carrier density longitudinal gradient- responsible for modes contending for the available material gain in the cavity- may be alleviated somewhat by segmenting the LC-DFB electrode into two or three reasonably interspaced longitudinal sections. In this work we report on the realization and performance of various electrode partition configurations. At room temperature, the experimental characterization of many as-cleaved LC-DFB devices provides ample evidence of superior performance such as a narrow linewidth (less than 400 kHz), a wide wavelength tune-ability (over 4 nm) and a hop-free single mode emission (side mode suppression ratio (SMSR) exceeding 54dB).

  4. 2-μm single longitudinal mode GaSb-based laterally coupled distributed feedback laser with regrowth-free shallow-etched gratings by interference lithography

    NASA Astrophysics Data System (ADS)

    Cheng-Ao, Yang; Yu, Zhang; Yong-Ping, Liao; Jun-Liang, Xing; Si-Hang, Wei; Li-Chun, Zhang; Ying-Qiang, Xu; Hai-Qiao, Ni; Zhi-Chuan, Niu

    2016-02-01

    We report a type-I GaSb-based laterally coupled distributed-feedback (LC-DFB) laser with shallow-etched gratings operating a continuous wave at room temperature without re-growth process. Second-order Bragg gratings are fabricated alongside the ridge waveguide by interference lithography. Index-coupled LC-DFB laser with a cavity of 1500 μm achieves single longitudinal mode continuous-wave operation at 20 °C with side mode suppression ratio (SMSR) as high as 24 dB. The maximum single mode continuous-wave output power is about 10 mW at room temperature (uncoated facet). A low threshold current density of 230 A/cm2 is achieved with differential quantum efficiency estimated to be 93 mW/A. The laser shows a good wavelength stability against drive current and working temperature. Project supported by the National Key Basic Research Program of China (Grant Nos. 2014CB643903 and 2013CB932904), the National Special Funds for the Development of Major Research Equipment and Instruments, China (Grant No. 2012YQ140005), the National Natural Science Foundation of China (Grant Nos. 61435012, 61274013, 61306088, and 61290303), and the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB01010200).

  5. Coupled ridge waveguide distributed feedback quantum cascade laser arrays

    SciTech Connect

    Liu, Ying-Hui; Zhang, Jin-Chuan Yan, Fang-Liang; Liu, Feng-Qi Zhuo, Ning; Wang, Li-Jun; Liu, Jun-Qi; Wang, Zhan-Guo

    2015-04-06

    A coupled ridge waveguide quantum cascade laser (QCL) array consisting of fifteen elements with parallel integration was presented. In-phase fundamental mode operation in each element is secured by both the index-guided nature of the ridge and delicate loss management by properly designed geometries of the ridges and interspaces. Single-lobe lateral far-field with a nearly diffraction limited beam pattern was obtained. By incorporating a one-dimensional buried distributed feedback grating, the in-phase-operating coupled ridge waveguide QCL design provides an efficient solution to obtaining high output power and stable single longitudinal mode emission. The simplicity of this structure and fabrication process makes this approach attractive to many practical applications.

  6. Feedback between ridge and swale bathymetry and barrier island storm response and transgression

    NASA Astrophysics Data System (ADS)

    Houser, Chris

    2012-11-01

    bathymetry emerged on the Gulf of Mexico shoreface it was able to reinforce the alongshore variation in dune height and storm response. It is further argued that the cuspate spits are reinforced by the shoreface ridges through alongshore transport of sediment from adjacent washover fans although the ridge orientation suggests that the spits have migrated westward by ~ 750 m. In this respect, the alongshore variation in beach and dune morphology on this island is the expression of this large-scale feedback and suggests a top-down model in which meso-scale processes and landforms depend on the geologic context.

  7. A Climactic Feedback? Variations in Mid-Ocean Ridge CO2 Emissions Driven by Glacial Cycles

    NASA Astrophysics Data System (ADS)

    Burley, J. M.; Katz, R. F.; Huybers, P. J.

    2015-12-01

    Changes in sea level associated with glacial cycles affect the pressure beneath a mid-ocean ridge (MOR) [1,2,3]. Pressure controls the depth of first melting, and therefore the rate of change of pressure controls the rate of change of the depth of first melting. The changing depth of first melting alters the effective rate at which mantle, and thus CO2, enters the melting region. Melt then transports CO2 to the ridge axis, where it enters the climate system. We calculate that the lag between sea level change and consequent variation in MOR CO2 emissions is 40-120 kyrs[4], similar to the timescale of glacial cycles. Could these variations in MOR CO2 emissions feed back on climate and lead to ice-age pacing at a small multiple of the obliquity period? [5]To test this hypothesis we begin with a climate model comprised of a global energy balance and a 1D ice sheet. The ice sheet flows under its own weight, accumulates due to precipitation, and melts in response to the local energy balance[6]. This model broadly replicates Early Pleistocene 40 kyr glacial cycles. We extend the model to include a variable greenhouse effect, according to atmospheric CO2, and variable MOR CO2 emissions driven by sea level. The lag between sea level change and MOR CO2 emissions is controlled by mantle permeability. If this model does not demonstrate MOR CO2 emissions altering glacial cycles, it would suggest this hypothesised feedback mechanism can be rejected. References[1] Huybers & Langmuir 2009; 10.1016/j.epsl.2009.07.014[2] Lund & Asimow 2011; 10.1029/2011GC003693[3] Crowley et al 2015; 10.1126/science.1261508[4] Burley & Katz 2015; 10.1016/j.epsl.2015.06.031[5] Huybers (in prep.)[6] Huybers & Tziperman 2008; 10.1029/2007PA001463

  8. Normalization Ridge Regression in Practice II: The Estimation of Multiple Feedback Linkages.

    ERIC Educational Resources Information Center

    Bulcock, J. W.

    The use of the two-stage least squares (2 SLS) procedure for estimating nonrecursive social science models is often impractical when multiple feedback linkages are required. This is because 2 SLS is extremely sensitive to multicollinearity. The standard statistical solution to the multicollinearity problem is a biased, variance reduced procedure…

  9. Feedback.

    ERIC Educational Resources Information Center

    Stenstrom, Anna-Brita

    A study of feedback in conversational question-response exchanges focused on the questioner's feedback to the respondent. It examined three types of "followup" moves: the ordinary type revealing the questioner's attitude to the response and closing the exchange; the type signaling the questioner's reaction to the response and inviting further…

  10. Time-resolved spectral characterization of ring cavity surface emitting and ridge-type distributed feedback quantum cascade lasers by step-scan FT-IR spectroscopy.

    PubMed

    Brandstetter, Markus; Genner, Andreas; Schwarzer, Clemens; Mujagic, Elvis; Strasser, Gottfried; Lendl, Bernhard

    2014-02-10

    We present the time-resolved comparison of pulsed 2nd order ring cavity surface emitting (RCSE) quantum cascade lasers (QCLs) and pulsed 1st order ridge-type distributed feedback (DFB) QCLs using a step-scan Fourier transform infrared (FT-IR) spectrometer. Laser devices were part of QCL arrays and fabricated from the same laser material. Required grating periods were adjusted to account for the grating order. The step-scan technique provided a spectral resolution of 0.1 cm(-1) and a time resolution of 2 ns. As a result, it was possible to gain information about the tuning behavior and potential mode-hops of the investigated lasers. Different cavity-lengths were compared, including 0.9 mm and 3.2 mm long ridge-type and 0.97 mm (circumference) ring-type cavities. RCSE QCLs were found to have improved emission properties in terms of line-stability, tuning rate and maximum emission time compared to ridge-type lasers.

  11. Audio Feedback -- Better Feedback?

    ERIC Educational Resources Information Center

    Voelkel, Susanne; Mello, Luciane V.

    2014-01-01

    National Student Survey (NSS) results show that many students are dissatisfied with the amount and quality of feedback they get for their work. This study reports on two case studies in which we tried to address these issues by introducing audio feedback to one undergraduate (UG) and one postgraduate (PG) class, respectively. In case study one…

  12. Metopic ridge

    MedlinePlus

    ... infant is made up of bony plates. The gaps between the plates allow for growth of the skull. The places where these plates connect are called sutures or suture lines. They do not fully close until the 2nd or 3rd year of life. A metopic ridge occurs when the ...

  13. Polar Ridges

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03662 Polar Ridges

    This ridge system is located in the south polar region.

    Image information: VIS instrument. Latitude -81.7N, Longitude 296.5E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  14. Supervisor Feedback.

    ERIC Educational Resources Information Center

    Hayman, Marilyn J.

    1981-01-01

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

  15. Distributed feedback lasers

    NASA Technical Reports Server (NTRS)

    Ladany, I.; Andrews, J. T.; Evans, G. A.

    1988-01-01

    A ridge waveguide distributed feedback laser was developed in InGaAsP. These devices have demonstrated CW output powers over 7 mW with threshold currents as low as 60 mA at 25 C. Measurements of the frequency response of these devices show a 3 dB bandwidth of about 2 GHz, which may be limited by the mount. The best devices have a single mode spectra over the entire temperature range tested with a side mode suppression of about 20 dB in both CW and pulsed modes. The design of this device, including detailed modeling of the ridge guide structure, effective index calculations, and a discussion of the grating configuration are presented. Also, the fabrication of the devices is presented in some detail, especially the fabrication of and subsequent growth over the grating. In addition, a high frequency fiber pigtailed package was designed and tested, which is a suitable prototype for a commercial package.

  16. Grafts for Ridge Preservation

    PubMed Central

    Jamjoom, Amal; Cohen, Robert E.

    2015-01-01

    Alveolar ridge bone resorption is a biologic phenomenon that occurs following tooth extraction and cannot be prevented. This paper reviews the vertical and horizontal ridge dimensional changes that are associated with tooth extraction. It also provides an overview of the advantages of ridge preservation as well as grafting materials. A Medline search among English language papers was performed in March 2015 using alveolar ridge preservation, ridge augmentation, and various graft types as search terms. Additional papers were considered following the preliminary review of the initial search that were relevant to alveolar ridge preservation. The literature suggests that ridge preservation methods and augmentation techniques are available to minimize and restore available bone. Numerous grafting materials, such as autografts, allografts, xenografts, and alloplasts, currently are used for ridge preservation. Other materials, such as growth factors, also can be used to enhance biologic outcome. PMID:26262646

  17. Single-Mode, Distributed Feedback Interband Cascade Lasers

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

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

  18. Manastash Ridge Observatory Autoguider Upgrade

    NASA Astrophysics Data System (ADS)

    Lozo, Jason; Huehnerhoff, Joseph; Armstrong, John; Davila, Adrian; Johnson, Courtney; McMaster, Alex; Olinger, Kyle

    2016-06-01

    The Astronomy Undergraduate Engineering Group (AUEG) at the University of Washington has designed and manufactured a novel autoguider system for the 0.8-meter telescope at the Manastash Ridge Observatory in Ellensburg, Washington. The system uses a pickoff mirror placed in the unused optical path, directing the outer field to the guide camera via a system of axi-symmetrically rotating relay mirrors (periscope). This allows the guider to sample nearly 7 times the area that would be possible with the same fixed detector. This system adds closed loop optical feedback to the tracking capabilities of the telescope. When tuned the telescope will be capable of acheiving 0.5 arcsecond tracking or better. Dynamic focusing of the primary optical path will also be an included feature of this system. This unique guider will be a much needed upgrade to the telescope allowing for increased scientific capability.

  19. Coress feedback

    PubMed Central

    2012-01-01

    This issue of CORESS feedback highlights yet again the importance of checking medications before administration and of adequate handover. Documentation of important medical data including drug allergies, as failed to happen in the case described below, is vital. We are grateful to the clinicians who have provided the material for these reports. The online reporting form is on our website (www.coress.org.uk), which also includes all previous feedback reports. Published contributions will be acknowledged by a ‘Certificate of Contribution’, which may be included in the contributor’s record of continuing professional development.

  20. Ridge Regression Signal Processing

    NASA Technical Reports Server (NTRS)

    Kuhl, Mark R.

    1990-01-01

    The introduction of the Global Positioning System (GPS) into the National Airspace System (NAS) necessitates the development of Receiver Autonomous Integrity Monitoring (RAIM) techniques. In order to guarantee a certain level of integrity, a thorough understanding of modern estimation techniques applied to navigational problems is required. The extended Kalman filter (EKF) is derived and analyzed under poor geometry conditions. It was found that the performance of the EKF is difficult to predict, since the EKF is designed for a Gaussian environment. A novel approach is implemented which incorporates ridge regression to explain the behavior of an EKF in the presence of dynamics under poor geometry conditions. The basic principles of ridge regression theory are presented, followed by the derivation of a linearized recursive ridge estimator. Computer simulations are performed to confirm the underlying theory and to provide a comparative analysis of the EKF and the recursive ridge estimator.

  1. Topographic Analysis of Europa's Ridges

    NASA Astrophysics Data System (ADS)

    Bader, C. E.; Kattenhorn, S. A.; Schenk, P. M.

    2008-12-01

    Ridges are the most ubiquitous surface feature on Europa. Here we examine double ridges that have two parallel, raised flanks with a continuous axial trough (referred to as a ridge pair). Characterizing ridge edifices may help us better understand the processes that drive ridge formation and evolution. Because there is no global elevation map for Europa, topography was derived from high resolution (18 to 181 m/pixel) combined stereographic and photoclinometric images to create 265 topographic profiles across 24 features of interest. Ridge topography was examined across 22 ridge pairs (12 with apparent lateral offsets) and 2 ridge complexes, in the Bright Plains, Conamara Chaos, Cilix, Argadnel Regio, Rhadamanthys Linea, and the E17DISSTR01 (northwest of Katreus Linea) areas. Topographic profiles are oriented perpendicular to the strike of each ridge pair to capture height and width variations as well as to highlight asymmetry between adjacent ridges. We characterize ridges using ridge height and width (vertical and horizontal distance from the base of the ridge flank to the ridge peak), average ridge height (average of the individual peaks in a ridge pair), total ridge width (distance between the ridge's outer flanks), and peak-to-peak (PTP) width (distance between peaks in a ridge pair). Height-to-width ratios of 44 individual ridges fall within a wide range that never exceeds 0.53, implying a maximum outer slope of 28 degrees, slightly less than the suggested angle of repose of loose granular ice (~34 degrees). Most slopes are much gentler, between 10 and 20 degrees, which are significantly smaller than those presented in a prior study undertaken early in the Galileo imaging mission. In fact, we have found that ridges can be very wide and low with outer slopes of only a few degrees, implying that very few ridge morphologies are likely to be controlled by granular flow processes down their outer slopes. The ratio of average ridge height to total ridge width has a

  2. Fingermark ridge drift.

    PubMed

    De Alcaraz-Fossoul, Josep; Roberts, Katherine A; Feixat, Carme Barrot; Hogrebe, Gregory G; Badia, Manel Gené

    2016-01-01

    Distortions of the fingermark topography are usually considered when comparing latent and exemplar fingerprints. These alterations are characterized as caused by an extrinsic action, which affects entire areas of the deposition and alters the overall flow of a series of contiguous ridges. Here we introduce a novel visual phenomenon that does not follow these principles, named fingermark ridge drift. An experiment was designed that included variables such as type of secretion (eccrine and sebaceous), substrate (glass and polystyrene), and degrees of exposure to natural light (darkness, shade, and direct light) indoors. Fingermarks were sequentially visualized with titanium dioxide powder, photographed and analyzed. The comparison between fresh and aged depositions revealed that under certain environmental conditions an individual ridge could randomly change its original position regardless of its unaltered adjacent ridges. The causes of the drift phenomenon are not well understood. We believe it is exclusively associated with intrinsic natural aging processes of latent fingermarks. This discovery will help explain the detection of certain dissimilarities at the minutiae/ridge level; determine more accurate "hits"; identify potentially erroneous corresponding points; and rethink identification protocols, especially the criteria of "no single minutiae discrepancy" for a positive identification.

  3. Fingermark ridge drift.

    PubMed

    De Alcaraz-Fossoul, Josep; Roberts, Katherine A; Feixat, Carme Barrot; Hogrebe, Gregory G; Badia, Manel Gené

    2016-01-01

    Distortions of the fingermark topography are usually considered when comparing latent and exemplar fingerprints. These alterations are characterized as caused by an extrinsic action, which affects entire areas of the deposition and alters the overall flow of a series of contiguous ridges. Here we introduce a novel visual phenomenon that does not follow these principles, named fingermark ridge drift. An experiment was designed that included variables such as type of secretion (eccrine and sebaceous), substrate (glass and polystyrene), and degrees of exposure to natural light (darkness, shade, and direct light) indoors. Fingermarks were sequentially visualized with titanium dioxide powder, photographed and analyzed. The comparison between fresh and aged depositions revealed that under certain environmental conditions an individual ridge could randomly change its original position regardless of its unaltered adjacent ridges. The causes of the drift phenomenon are not well understood. We believe it is exclusively associated with intrinsic natural aging processes of latent fingermarks. This discovery will help explain the detection of certain dissimilarities at the minutiae/ridge level; determine more accurate "hits"; identify potentially erroneous corresponding points; and rethink identification protocols, especially the criteria of "no single minutiae discrepancy" for a positive identification. PMID:26646735

  4. Long-term interaction between mid-ocean ridges and mantle plumes

    NASA Astrophysics Data System (ADS)

    Whittaker, J. M.; Afonso, J. C.; Masterton, S.; Müller, R. D.; Wessel, P.; Williams, S. E.; Seton, M.

    2015-06-01

    Plate tectonic motions are commonly considered to be driven by slab pull at subduction zones and ridge push at mid-ocean ridges, with motion punctuated by plumes of hot material rising from the lower mantle. Within this model, the geometry and location of mid-ocean ridges are considered to be independent of lower-mantle dynamics, such as deeply sourced plumes that produce voluminous lava eruptions--termed large igneous provinces. Here we use a global plate model to reconstruct the locations of large igneous provinces relative to plumes and mid-ocean ridges at the time they formed. We find that large igneous provinces repeatedly formed at specific locations where mid-ocean ridges and plumes interact. We calculate how much mantle material was converted to oceanic lithosphere at the mid-ocean ridges and find that slowly migrating ridge systems that have been stabilized by upwelling plumes have extracted large volumes of material from the same part of the upper mantle over periods up to 180 million years. The geochemical signatures of mid-ocean ridge basalts and seismic tomographic data show that upper-mantle temperatures are elevated at significant distances from ridge-plume interactions, indicating a far-field, indirect influence of plume-ridge interactions on the upper-mantle structure. We conclude that strong feedbacks exist between the dynamics of slowly migrating ridges and deeply sourced plumes.

  5. Student Engagement with Feedback

    ERIC Educational Resources Information Center

    Scott, Jon; Shields, Cathy; Gardner, James; Hancock, Alysoun; Nutt, Alex

    2011-01-01

    This report considers Biological Sciences students' perceptions of feedback, compared with those of the University as a whole, this includes what forms of feedback were considered most useful and how feedback used. Compared with data from previous studies, Biological Sciences students gave much greater recognition to oral feedback, placing it on a…

  6. Contextual view of Point Bonita Ridge, showing Bonita Ridge access ...

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

    Contextual view of Point Bonita Ridge, showing Bonita Ridge access road retaining wall and location of Signal Corps Radar (S.C.R.) 296 Station 5 Transmitter Building foundation (see stake at center left), camera facing north - Fort Barry, Signal Corps Radar 296, Station 5, Transmitter Building Foundation, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

  7. Feedback on Feedback--Does It Work?

    ERIC Educational Resources Information Center

    Speicher, Oranna; Stollhans, Sascha

    2015-01-01

    It is well documented that providing assessment feedback through the medium of screencasts is favourably received by students and encourages deeper engagement with the feedback given by the language teacher (inter alia Abdous & Yoshimura, 2010; Brick & Holmes, 2008; Cann, 2007; Stannard, 2007). In this short paper we will report the…

  8. Height ridges of oriented medialness

    NASA Astrophysics Data System (ADS)

    Furst, Jacob David

    Shape analysis of objects is an important aspect of medical image processing. Information gained from shape analysis can be used for object segmentation, object- based registration and object visualization. One shape analysis tool is the core, defined to be a height ridge of a medial strength measure made on an image. In this dissertation I present 3D cores, defined here to be optimal scale-orientation height ridges of oriented medial strength measurements. This dissertation covers (1)a medial strength measurement, Blum- like medialness, that is robust, efficient, and insensitive to intrafigural interference, (2)a new definition for a ridge, the optimal parameter height ridge, and its properties, and (3)an algorithm, Marching Ridges, for extracting cores. The medial strength measurement uses Gaussian derivatives, so is insensitive to noise, and responds to object boundaries at points rather than on entire spheres, so is faster to calculate and less sensitive to boundaries of other image figures. The Marching Ridges algorithm uses the grid structure of the image domain to identify ridge points as zero-crossings of first derivatives and to track ridges through the image domain. I include results of this algorithm on medical images of cerebral vasculature, a skull, kidneys, and brain ventricles.

  9. Polygonal Ridge Networks on Mars

    NASA Astrophysics Data System (ADS)

    Kerber, Laura; Dickson, James; Grosfils, Eric; Head, James W.

    2016-10-01

    Polygonal ridge networks, also known as boxwork or reticulate ridges, are found in numerous locations and geological contexts across Mars. While networks formed from mineralized fractures hint at hot, possibly life-sustaining circulating ground waters, networks formed by impact-driven clasting diking, magmatic dikes, gas escape, or lava flows do not have the same astrobiological implications. Distinguishing the morphologies and geological context of the ridge networks sheds light on their potential as astrobiological and mineral resource sites of interest. The most widespread type of ridge morphology is characteristic of the Nili Fossae and Nilosyrtis region and consists of thin, criss-crossing ridges with a variety of heights, widths, and intersection angles. They are found in ancient Noachian terrains at a variety of altitudes and geographic locations and may be a mixture of clastic dikes, brecciated dikes, and mineral veins. They occur in the same general areas as valley networks and ancient lake basins, but they are not more numerous where these features are concentrated, and can appear in places where they morphologies are absent. Similarly, some of the ridge networks are associated with hydrated mineral detections, but some occur in locations without detections. Smaller, light-toned ridges of variable widths have been found in Gale Crater and other rover sites and are interpreted to be smaller version of the Nili-like ridges, in this case formed by the mineralization of fractures. This type of ridge is likely to be found in many other places on Mars as more high-resolution data becomes available. Hellas Basin is host to a third type of ridge morphology consisting of large, thick, light-toned ridges forming regular polygons at several superimposed scales. While still enigmatic, these are most likely to be the result of sediment-filled fractures. The Eastern Medusae Fossae Formation contains large swaths of a fourth, previously undocumented, ridge network type

  10. Chromaticity Feedback at RHIC

    SciTech Connect

    Marusic, A.; Minty, M.; Tepikian, S.

    2010-05-23

    Chromaticity feedback during the ramp to high beam energies has been demonstrated in the Relativistic Heavy Ion Collider (RHIC). In this report we review the feedback design and measurement technique. Commissioning experiences including interaction with existing tune and coupling feedback are presented together with supporting experimental data.

  11. The Mythology of Feedback

    ERIC Educational Resources Information Center

    Adcroft, Andy

    2011-01-01

    Much of the general education and discipline-specific literature on feedback suggests that it is a central and important element of student learning. This paper examines feedback from a social process perspective and suggests that feedback is best understood through an analysis of the interactions between academics and students. The paper argues…

  12. Preventing Feedback Fizzle

    ERIC Educational Resources Information Center

    Brookhart, Susan M.

    2012-01-01

    Feedback is certainly about saying or writing helpful, learning-focused comments. But that is only part of it. What happens beforehand? What happens afterward? Feedback that is helpful and learning-focused fits into a context. Before a teacher gives feedback, students need to know the learning target so they have a purpose for using the feedback…

  13. Developing Sustainable Feedback Practices

    ERIC Educational Resources Information Center

    Carless, David; Salter, Diane; Yang, Min; Lam, Joy

    2011-01-01

    Feedback is central to the development of student learning, but within the constraints of modularized learning in higher education it is increasingly difficult to handle effectively. This article makes a case for sustainable feedback as a contribution to the reconceptualization of feedback processes. The data derive from the Student Assessment and…

  14. Effect of ridge-ridge interactions in crumpled thin sheets

    NASA Astrophysics Data System (ADS)

    Liou, Shiuan-Fan; Lo, Chun-Chao; Chou, Ming-Han; Hsiao, Pai-Yi; Hong, Tzay-Ming

    2014-02-01

    We study whether and how the energy scaling based on the single-ridge approximation is revised in an actual crumpled sheet, namely, in the presence of ridge-ridge interactions. Molecular dynamics simulation is employed for this purpose. In order to improve the data quality, modifications are introduced to the common protocol. As crumpling proceeds, we find that the average storing energy changes from being proportional to one-third of the ridge length to a linear relation, while the ratio of bending and stretching energies decreases from 5 to 2. The discrepancy between previous simulations and experiments on the material-dependence for the power-law exponent is resolved. We further determine the average ridge length to scale as 1/D1/3, the ridge number as D2/3, and the average storing energy per unit ridge length as D0.881 where D denotes the volume density of the crumpled ball. These results are accompanied by experimental proofs and are consistent with mean-field predictions. Finally, we extend the existent simulations to the high-pressure region and verify the existence of a scaling relation that is more general than the familiar power law at covering the whole density range.

  15. Learning experiences at Oak Ridge

    SciTech Connect

    White, R.K.

    1990-01-01

    The Oak Ridge Operations (ORO) of DOE has organized an Environmental Restoration Program to handle environmental cleanup activitis for the Oak Ridge Reservation (ORR) following General Watkins' reorganization at DOE Headquarters. Based on the major facilities and locations of contamination sites, the Environmental Restoration Program is divided into five subprograms: Oak Ridge, National Laboatory (ORNL) sites, y-12 Plant sites, Oak Ridge Gaseous Diffusion Plant (ORGDP) sites, Oak Ridge Associated Universities (ORAU) sites and off-site areas. The Office of Risk Analysis at ORNL was established under the auspices of the Environmental Restoration Program to implement Superfun legislation in the five subprograms of DOE-ORO. Risk assessment must examine protetial human health and ecological impacts from contaminant sources that range from highly radioactive materials to toxic chemicals and mixed wastes. The remedial alternatives we are evaluating need to reach acceptable levels of risk effectively while also being cost-efficient. The purpose of this paper is to highlight areas of particular interest and concern at Oak Ridge and to discuss, where possible, solutions implemented by the Oak Ridge Environmental Restoation Program.

  16. Sample Grating Distributed Feedback Quantum Cascade Laser Array.

    PubMed

    Yan, F L; Zhang, J C; Liu, C W; Zhuo, N; Liu, Fq; Zhai, S Q; Wang, Z G

    2015-12-01

    A sample grating distributed feedback quantum cascade laser array aim at broad tunability and enhanced side mode suppression ratios is presented. Utilizing a sample grating dependence on emission wavelength and epitaxial side down bonding technique, the array of laser ridges exhibited three separated single mode emissions centered at 4.760, 4.721, and 4.711 μm respectively, in continuous wave at room temperature. Side mode suppression ratios of >35 dB and continuous wave output powers of >10 mW per laser ridge were obtained.

  17. Ridge 2000 Data Management System

    NASA Astrophysics Data System (ADS)

    Goodwillie, A. M.; Carbotte, S. M.; Arko, R. A.; Haxby, W. F.; Ryan, W. B.; Chayes, D. N.; Lehnert, K. A.; Shank, T. M.

    2005-12-01

    Hosted at Lamont by the marine geoscience Data Management group, mgDMS, the NSF-funded Ridge 2000 electronic database, http://www.marine-geo.org/ridge2000/, is a key component of the Ridge 2000 multi-disciplinary program. The database covers each of the three Ridge 2000 Integrated Study Sites: Endeavour Segment, Lau Basin, and 8-11N Segment. It promotes the sharing of information to the broader community, facilitates integration of the suite of information collected at each study site, and enables comparisons between sites. The Ridge 2000 data system provides easy web access to a relational database that is built around a catalogue of cruise metadata. Any web browser can be used to perform a versatile text-based search which returns basic cruise and submersible dive information, sample and data inventories, navigation, and other relevant metadata such as shipboard personnel and links to NSF program awards. In addition, non-proprietary data files, images, and derived products which are hosted locally or in national repositories, as well as science and technical reports, can be freely downloaded. On the Ridge 2000 database page, our Data Link allows users to search the database using a broad range of parameters including data type, cruise ID, chief scientist, geographical location. The first Ridge 2000 field programs sailed in 2004 and, in addition to numerous data sets collected prior to the Ridge 2000 program, the database currently contains information on fifteen Ridge 2000-funded cruises and almost sixty Alvin dives. Track lines can be viewed using a recently- implemented Web Map Service button labelled Map View. The Ridge 2000 database is fully integrated with databases hosted by the mgDMS group for MARGINS and the Antarctic multibeam and seismic reflection data initiatives. Links are provided to partner databases including PetDB, SIOExplorer, and the ODP Janus system. Improved inter-operability with existing and new partner repositories continues to be

  18. Ridges on Europa

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This is the highest resolution picture ever taken of the Jupiter moon, Europa. The area shown is about 5.9 by 9.9 miles (9.6 by 16 kilometers) and the smallest visible feature is about the size of a football field. In this view, the ice-rich surface has been broken into a complex pattern by cross-cutting ridges and grooves resulting from tectonic processes. Sinuous rille-like features and knobby terrain could result from surface modifications of unknown origins. Small craters of possible impact origin range in size from less than 330 feet (100 meters) to about 1300 feet (400 meters) across are visible.

    This image was taken by the solid state imaging television camera aboard the Galileo during its fourth orbit around Jupiter, at a distance of 2060 miles (3340 kilometers). The picture is centered at 325 degrees West, 5.83 degrees North. North is toward the top of this image, with the sun shining from the right.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  19. The Mid-Ocean Ridge.

    ERIC Educational Resources Information Center

    Macdonald, Kenneth C.; Fox, Paul J.

    1990-01-01

    Described are concepts involved with the formation and actions of the Mid-Ocean Ridge. Sea-floor spreading, the magma supply model, discontinuities, off-axis structures, overlaps and deviation, and aquatic life are discussed. (CW)

  20. Growth of a tectonic ridge

    SciTech Connect

    Fleming, R.W.; Messerich, J.A.; Johnson, A.M.

    1997-12-31

    The 28 June 1992 Landers, California, earthquake of M 7.6 created an impressive record of surface rupture and ground deformation. Fractures extend over a length of more than 80 km including zones of right-lateral shift, steps in the fault zones, fault intersections and vertical changes. Among the vertical changes was the growth of a tectonic ridge described here. In this paper the authors describe the Emerson fault zone and the Tortoise Hill ridge including the relations between the fault zone and the ridge. They present data on the horizontal deformation at several scales associated with activity within the ridge and belt of shear zones and show the differential vertical uplifts. And, they conclude with a discussion of potential models for the observed deformation.

  1. Neural cryptography with feedback.

    PubMed

    Ruttor, Andreas; Kinzel, Wolfgang; Shacham, Lanir; Kanter, Ido

    2004-04-01

    Neural cryptography is based on a competition between attractive and repulsive stochastic forces. A feedback mechanism is added to neural cryptography which increases the repulsive forces. Using numerical simulations and an analytic approach, the probability of a successful attack is calculated for different model parameters. Scaling laws are derived which show that feedback improves the security of the system. In addition, a network with feedback generates a pseudorandom bit sequence which can be used to encrypt and decrypt a secret message.

  2. Feedback stabilization initiative

    SciTech Connect

    1997-06-01

    Much progress has been made in attaining high confinement regimes in magnetic confinement devices. These operating modes tend to be transient, however, due to the onset of MHD instabilities, and their stabilization is critical for improved performance at steady state. This report describes the Feedback Stabilization Initiative (FSI), a broad-based, multi-institutional effort to develop and implement methods for raising the achievable plasma betas through active MHD feedback stabilization. A key element in this proposed effort is the Feedback Stabilization Experiment (FSX), a medium-sized, national facility that would be specifically dedicated to demonstrating beta improvement in reactor relevant plasmas by using a variety of MHD feedback stabilization schemes.

  3. Carpenter Ridge Tuff, CO

    NASA Astrophysics Data System (ADS)

    Bachmann, Olivier; Deering, Chad D.; Lipman, Peter W.; Plummer, Charles

    2014-06-01

    The ~1,000 km3 Carpenter Ridge Tuff (CRT), erupted at 27.55 Ma during the mid-tertiary ignimbrite flare-up in the western USA, is among the largest known strongly zoned ash-flow tuffs. It consists primarily of densely welded crystal-poor rhyolite with a pronounced, highly evolved chemical signature (high Rb/Sr, low Ba, Zr, Eu), but thickly ponded intracaldera CRT is capped by a more crystal-rich, less silicic facies. In the outflow ignimbrite, this upper zone is defined mainly by densely welded crystal-rich juvenile clasts of trachydacite composition, with higher Fe-Ti oxide temperatures, and is characterized by extremely high Ba (to 7,500 ppm), Zr, Sr, and positive Eu anomalies. Rare mafic clasts (51-53 wt% SiO2) with Ba contents to 4,000-5,000 ppm and positive Eu anomalies are also present. Much of the major and trace-element variations in the CRT juvenile clasts can be reproduced via in situ differentiation by interstitial melt extraction from a crystal-rich, upper-crustal mush zone, with the trachydacite, crystal-rich clasts representing the remobilized crystal cumulate left behind by the melt extraction process. Late recharge events, represented by the rare mafic clasts and high-Al amphiboles in some samples, mixed in with parts of the crystal cumulate and generated additional scatter in the whole-rock data. Recharge was important in thermally remobilizing the silicic crystal cumulate by partially melting the near-solidus phases, as supported by: (1) ubiquitous wormy/sieve textures and reverse zoning patterns in feldspars and biotites, (2) absence of quartz in this very silicic unit stored at depths of >4-5 km, and (3) heterogeneous melt compositions in the trachydacite fiamme and mafic clasts, particularly in Ba, indicating local enrichment of this element due mostly to sanidine and biotite melting. The injection of hot, juvenile magma into the upper-crustal cumulate also imparted the observed thermal gradient to the deposits and the mixing overprint that

  4. The Power of Feedback

    ERIC Educational Resources Information Center

    Hattie, John; Timperley, Helen

    2007-01-01

    Feedback is one of the most powerful influences on learning and achievement, but this impact can be either positive or negative. Its power is frequently mentioned in articles about learning and teaching, but surprisingly few recent studies have systematically investigated its meaning. This article provides a conceptual analysis of feedback and…

  5. Four perspectives on climate feedbacks

    NASA Astrophysics Data System (ADS)

    Feldl, N.; Roe, G. H.

    2013-08-01

    The spatial pattern of climate feedbacks depends on how the feedbacks are defined. We employ an idealized aquaplanet simulation with radiative kernels diagnosed for the precise model setup and characterize the meridional structure of feedbacks under four different definitions: local feedbacks, global feedbacks, nondimensional feedback factors, and relative humidity feedbacks. First, the spatial pattern of the reference response (i.e., the Planck feedback) is found to vary with definition, largely as a consequence of polar-amplified warming, which affects other high-latitude feedbacks as well. Second, locally defined feedbacks allow for decomposition of the surface temperature response as a function of feedbacks, forcing, and heat transport. Third, different insights into the dynamical and thermodynamical underpinnings of the subtropical moisture response are gained by comparing different versions of humidity feedbacks. Thus, alternative approaches to the conventional, global definition of feedbacks offer several advantages for understanding patterns of warming and, ultimately, regional climate predictability.

  6. Designing Genetic Feedback Controllers.

    PubMed

    Harris, Andreas W K; Dolan, James A; Kelly, Ciarán L; Anderson, James; Papachristodoulou, Antonis

    2015-08-01

    By incorporating feedback around systems we wish to manipulate, it is possible to improve their performance and robustness properties to meet pre-specified design objectives. For decades control engineers have been successfully implementing feedback controllers for complex mechanical and electrical systems such as aircraft and sports cars. Natural biological systems use feedback extensively for regulation and adaptation but apart from the most basic designs, there is no systematic framework for designing feedback controllers in Synthetic Biology. In this paper we describe how classical approaches from linear control theory can be used to close the loop. This includes the design of genetic circuits using feedback control and the presentation of a biological phase lag controller. PMID:26390502

  7. Global and regional ridge patterns on Mars

    NASA Technical Reports Server (NTRS)

    Chicarro, A. F.; Schultz, P. H.; Masson, P.

    1985-01-01

    A systematic study of Martian wrinkle ridges was performed to synthesize a theory of the planetary interior forces which produced such surface features. The survey was carried out using Mariner-9 and Viking orbiter imagery. Attention was given to the global distributions of ridge types in terms of geologic and tectonic surrounds, and to the orientation of ridges relative to impact basins. High/low relief ridges, ridge wings and rectilinear ridges were examined. Ridge orientation and distribution were found to be controlled by the forces of formation and modification of impact basins. Several other conclusions were reached regarding basin-concentric ridge patterns, regional stress patterns, regions of the most numerous ridges, and the location of a major compressive zone.

  8. PROPAGATION AND LINKAGE OF OCEANIC RIDGE SEGMENTS.

    USGS Publications Warehouse

    Pollard, David D.; Aydin, Atilla

    1984-01-01

    An investigation was made of spreading ridges and the development of structures that link ridge segments using an analogy between ridges and cracks in elastic plates. The ridge-propagation force and a path factor that controls propagation direction were calculated for echelon ridge segments propagating toward each other. The ridge-propagation force increases as ridge ends approach but then declines sharply as the ends pass, so ridge segments may overlap somewhat. The sign of the path factor changes as ridge ends approach and pass, so the overlapping ridge ends may diverge and then converge following a hook-shaped path. The magnitudes of shear stresses in the plane of the plate and orientations of maximum shear planes between adjacent ridge segments were calculated to study transform faulting. For different loading conditions simulating ridge push, plate pull, and ridge suction, a zone of intense mechanical interaction between adjacent ridge ends in which stresses are concentrated was identified. The magnitudes of mean stresses in the plane of the plate and orientations of principal stress planes were also calculated.

  9. Comparison of Ridges on Triton and Europa

    NASA Technical Reports Server (NTRS)

    Prockter, L. M.; Pappalardo, R. .

    2003-01-01

    Triton and Europa each display a variety of ridges and associated troughs. The resemblance of double ridges on these two satellites has been previously noted [R. Kirk, pers. comm.], but as yet, the similarities and differences between these feature types have not been examined in any detail. Triton s ridges, and Europa s, exhibit an evolutionary sequence ranging from isolated troughs, through doublet ridges, to complex ridge swaths [1, 2]. Comparison of ridges on Europa to those on Triton may provide insight into their formation on both satellites, and thereby have implications for the satellites' histories.

  10. Strategies for effective feedback.

    PubMed

    Kritek, Patricia A

    2015-04-01

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

  11. Feedback in distance education.

    PubMed

    Hudspeth, D

    1988-01-01

    Some tips, strategies, and techniques are presented for incorporating learner feedback into distance education courses. The most common form of learner feedback is immediate Knowledge of Response (KR). This general term can be delineated further as either Knowledge of Correct Response (KCR) or Knowledge of Incorrect Response (KIR). KCR is most useful for learning tasks that require a high level of automatic response such as vocabulary development and naming chemical structures. It also can be used for higher levels of learning. KIR occurs when the learner makes a response and knows only whether the response was correct or incorrect. If the learner was incorrect, the correct answer is not provided. Distant learners, as well as learners in a typical classroom, benefit from positive feedback, e.g., a few words written on the side of an assignment or a short note of encouragement. Personalized feedback tells students if they are performing satisfactorily and, if provided early in a course, can help reduce student attrition. If immediate feedback after an examination cannot be provided, every effort should be made to score and return the test as soon as possible before the student is expected to begin study on subsequent lessons. If this is not possible, a test review sheet could be mailed back upon receipt of the examination. Microcomputers are devices that can provide rapid and useful feedback, yet many methods that do not rely on computers can provide feedback. These include practice tests, small group exercises, and checklist response sheets. In addition to formally providing feedback after an assignment or examination, it is possible to use the principles of feedback by embedding questions and answers in text, audio, or video materials.

  12. Global Feedback Simulator

    SciTech Connect

    Carlos Serrano, Lawrence Doolittle

    2015-10-29

    GFS is a simulation engine that is used for the characterization of Accelerator performance parameters based on the machine layout, configuration and noise sources. It combines extensively tested Feedback models with a longitudinal phase space tracking simulator along with the interaction between the two via beam-based feedback using a computationally efficient simulation engine. The models include beam instrumentation, considerations on loop delays for in both the R and beam-based feedback loops, as well as the ability to inject noise (both correlated and uncorrelated) at different points of the machine including a full characterization of the electron gun performance parameters.

  13. Global Feedback Simulator

    2015-10-29

    GFS is a simulation engine that is used for the characterization of Accelerator performance parameters based on the machine layout, configuration and noise sources. It combines extensively tested Feedback models with a longitudinal phase space tracking simulator along with the interaction between the two via beam-based feedback using a computationally efficient simulation engine. The models include beam instrumentation, considerations on loop delays for in both the R and beam-based feedback loops, as well as themore » ability to inject noise (both correlated and uncorrelated) at different points of the machine including a full characterization of the electron gun performance parameters.« less

  14. The Ridge, the Glasma and Flow

    SciTech Connect

    McLerran,L.

    2008-09-15

    I discuss the ridge phenomena observed in heavy ion collisions at RHIC. I argue that the ridge may be due to flux tubes formed from the Color Glass Condensate in the early Glasma phase of matter produced in such collisions.

  15. Oak Ridge callibration recall program

    SciTech Connect

    Falter, K.G.; Wright, W.E.; Pritchard, E.W.

    1996-12-31

    A development effort was initiated within the Oak Ridge metrology community to address the need for a more versatile and user friendly tracking database that could be used across the Oak Ridge complex. This database, which became known as the Oak Ridge Calibration Recall Program (ORCRP), needed to be diverse enough for use by all three Oak Ridge facilities, as well as the seven calibration organizations that support them. Various practical functions drove the initial design of the program: (1) accessible by any user at any site through a multi-user interface, (2) real-time database that was able to automatically generate e-mail notices of due and overdue measuring and test equipment, (3) large memory storage capacity, and (4) extremely fast data access times. In addition, the program needed to generate reports on items such as instrument turnaround time, workload projections, and laboratory efficiency. Finally, the program should allow the calibration intervals to be modified, based on historical data. The developed program meets all of the stated requirements and is accessible over a network of computers running Microsoft Windows software.

  16. Ridge Regression for Interactive Models.

    ERIC Educational Resources Information Center

    Tate, Richard L.

    1988-01-01

    An exploratory study of the value of ridge regression for interactive models is reported. Assuming that the linear terms in a simple interactive model are centered to eliminate non-essential multicollinearity, a variety of common models, representing both ordinal and disordinal interactions, are shown to have "orientations" that are favorable to…

  17. Making Time for Feedback

    ERIC Educational Resources Information Center

    Fisher, Douglas; Frey, Nancy

    2012-01-01

    Ask any teacher what he or she needs more of, and it is a good bet that time will top the list. Anything that promises to recoup a little bit of their workday time is sure to be a best seller. One overlooked time-saver is in how they use feedback. Teachers know that feedback is important for teaching and learning. Unfortunately, most secondary…

  18. Feedback and rewards, part II: formal and informal feedback reviews.

    PubMed

    Harolds, Jay

    2013-02-01

    There are 2 major classes of feedback. One class of feedback consists of the informal, numerous conversations between various people in the organization regarding the performance, behavior, and goals of an individual. Another class of feedback consists of formal reviews held once or twice a year between a supervisor and an individual. This article discusses both types of feedback.

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

    PubMed

    Harolds, Jay A

    2013-01-01

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

  20. Seven Keys to Effective Feedback

    ERIC Educational Resources Information Center

    Wiggins, Grant

    2012-01-01

    The term "feedback" is often used to describe all kinds of comments made after the fact, including advice, praise, and evaluation. But none of these are feedback, strictly speaking. Basically, feedback is information about how one is doing in his or her efforts to reach a goal. Whether feedback is just there to be grasped or is provided by another…

  1. Feedback: How Does It Function?

    ERIC Educational Resources Information Center

    Bardwell, Rebecca

    1981-01-01

    A study of feedback delay, expectation, and development was conducted in grades four, six, and eight, to assess whether feedback on a school related learning task serves an informational or reinforcing function. Results indicate that feedback serves an informational function and delayed feedback facilitates retention, contrary to reinforcement…

  2. Global climate feedbacks

    SciTech Connect

    Manowitz, B.

    1990-10-01

    The important physical, chemical, and biological events that affect global climate change occur on a mesoscale -- requiring high spatial resolution for their analysis. The Department of Energy has formulated two major initiatives under the US Global Change Program: ARM (Atmospheric Radiation Measurements), and CHAMMP (Computer Hardware Advanced Mathematics and Model Physics). ARM is designed to use ground and air-craft based observations to document profiles of atmospheric composition, clouds, and radiative fluxes. With research and models of important physical processes, ARM will delineate the relationships between trace gases, aerosol and cloud structure, and radiative transfer in the atmosphere, and will improve the parameterization of global circulation models. The present GCMs do not model important feedbacks, including those from clouds, oceans, and land processes. The purpose of this workshop is to identify such potential feedbacks, to evaluate the uncertainties in the feedback processes (and, if possible, to parameterize the feedback processes so that they can be treated in a GCM), and to recommend research programs that will reduce the uncertainties in important feedback processes. Individual reports are processed separately for the data bases.

  3. Structural processes at slow-spreading ridges.

    PubMed

    Mutter, J C; Karson, J A

    1992-07-31

    Slow-spreading (<35 millimeters per year) mid-ocean ridges are dominated by segmented, asymmetric, rifted depressions like continental rifts. Fast-spreading ridges display symmetric, elevated volcanic edifices that vary in shape and size along axis. Deep earthquakes, major normal faults, and exposures of lower crustal rocks are common only along slow-spreading ridges. These contrasting features suggest that mechanical deformation is far more important in crustal formation at slow-spreading ridges than at fast-spreading ridges. New seismic images suggest that the nature and scale of segmentation of slow-spreading ridges is integral to the deformational process and not to magmatic processes that may control segmentation on fast-spreading ridges.

  4. Microwave ridged waveguide beam pickups

    SciTech Connect

    Suddeth, D.

    1985-01-01

    Sensitive broad-band beam pickups are a prerequisite for improved stochastic beam cooling. The 2-4 GHz and the 4-8 GHz bands have been of particular interest for stochastic cooling applications. This report summarizes the striking results of an investigation of ridged waveguide pickups at Argonne. An upper-to-lower frequency ratio of 2.4:1 is readily obtained with a ridged waveguide as compared to 1.5:1 with a standard waveguide. Wire measurements and tests at the Argonne beam test facility indicate an approximate 20% increase in gain per unit over a stripline with comparable longitudinal spacing. Another advantage of waveguide pickups is construction simplicity. The output is easily coupled to a transmission line. Descriptions of the design, construction, and results are included in this report.

  5. Status of Blue Ridge Reservoir

    SciTech Connect

    Not Available

    1990-09-01

    This is one in a series of reports prepared by the Tennessee Valley Authority (TVA) for those interested in the conditions of TVA reservoirs. This overview of Blue Ridge Reservoir summarizes reservoir and watershed characteristics, reservoir uses and use impairments, water quality and aquatic biological conditions, and activities of reservoir management agencies. This information was extracted from the most current reports and data available, as well as interview with water resource professionals in various federal, state, and local agencies. Blue Ridge Reservoir is a single-purpose hydropower generating project. When consistent with this primary objective, the reservoir is also operated to benefit secondary objectives including water quality, recreation, fish and aquatic habitat, development of shoreline, aesthetic quality, and other public and private uses that support overall regional economic growth and development. 8 refs., 1 fig.

  6. Oak Ridge National Laboratory Review

    SciTech Connect

    Krause, C.; Pearce, J.; Zucker, A.

    1992-01-01

    This report presents brief descriptions of the following programs at Oak Ridge National Laboratory: The effects of pollution and climate change on forests; automation to improve the safety and efficiency of rearming battle tanks; new technologies for DNA sequencing; ORNL probes the human genome; ORNL as a supercomputer research center; paving the way to superconcrete made with polystyrene; a new look at supercritical water used in waste treatment; and small mammals as environmental monitors.

  7. STABILIZED FEEDBACK AMPLIFIER

    DOEpatents

    Fishbine, H.L.; Sewell, C. Jr.

    1957-08-01

    Negative feedback amplifiers, and particularly a negative feedback circuit which is economical on amode power consumption, are described. Basically, the disclosed circuit comprises two tetrode tubes where the output of the first tube is capacitamce coupled to the grid of the second tube, which in turn has its plate coupled to the cathode of the first tube to form a degenerative feedback circuit. Operating potential for screen of the second tube is supplied by connecting the cathode resistor of the first tube to the screen, while the screen is by-passed to the cathode of its tube for the amplified frequencies. Also, the amplifier incorporates a circuit to stabilize the transconductance of the tubes by making the grid potential of each tube interdependent on anode currents of both lubes by voltage divider circuitry.

  8. Stratospheric water vapor feedback.

    PubMed

    Dessler, A E; Schoeberl, M R; Wang, T; Davis, S M; Rosenlof, K H

    2013-11-01

    We show here that stratospheric water vapor variations play an important role in the evolution of our climate. This comes from analysis of observations showing that stratospheric water vapor increases with tropospheric temperature, implying the existence of a stratospheric water vapor feedback. We estimate the strength of this feedback in a chemistry-climate model to be +0.3 W/(m(2)⋅K), which would be a significant contributor to the overall climate sensitivity. One-third of this feedback comes from increases in water vapor entering the stratosphere through the tropical tropopause layer, with the rest coming from increases in water vapor entering through the extratropical tropopause. PMID:24082126

  9. Stratospheric water vapor feedback

    PubMed Central

    Dessler, A. E.; Schoeberl, M. R.; Wang, T.; Davis, S. M.; Rosenlof, K. H.

    2013-01-01

    We show here that stratospheric water vapor variations play an important role in the evolution of our climate. This comes from analysis of observations showing that stratospheric water vapor increases with tropospheric temperature, implying the existence of a stratospheric water vapor feedback. We estimate the strength of this feedback in a chemistry–climate model to be +0.3 W/(m2⋅K), which would be a significant contributor to the overall climate sensitivity. One-third of this feedback comes from increases in water vapor entering the stratosphere through the tropical tropopause layer, with the rest coming from increases in water vapor entering through the extratropical tropopause. PMID:24082126

  10. Augmented kinematic feedback system

    NASA Astrophysics Data System (ADS)

    Andert, Ed P., Jr.; Archipley-Smith, Donna K.

    1994-07-01

    This paper discusses a real-time augmented kinematic feedback system which can be used as a diagnosis tool for individuals with motor disabilities. The system captures and analyzes movement via color targets attached to an individual and then feeds back information about movement kinematics. This target tracking approach has a high potential for achieving a real- time kinematic assessment capability. The approach recognizes distinct moving colored targets using video data. Multiple colored targets are attached to an individual at strategic locations and then target movement is tracked using a video data acquisition system. The ability to track and assess movement in real-time allows researchers and practitioners to better study and potentially treat various motor disabilities. Recent research has suggested that kinematic feedback can enhance motor recovery of disabled individuals. This approach addresses the need for a real-time measure of human movement and discusses using kinematic feedback to enhance disability recovery.

  11. TUNE FEEDBACK AT RHIC

    SciTech Connect

    CAMERON,P.; CERNIGLIA,P.; CONNOLLY,R.; CUPOLO,J.; DAWSON,W.C.; DEGEN,C.; DELLAPENNA,A.; DELONG,J.; DREES,A.; HUHN,A.; KESSELMAN,M.; MARUSIC,A.; OERTER,B.; MEAD,J.; SCHULTHEISS,C.; SIKORA,R.; VAN ZEIJTS,J.

    2001-06-18

    Preliminary phase-locked loop betatron tune measurement results were obtained during RHIC 2000 with a resonant Beam Position Monitor. These results suggested the possibility of incorporating PLL tune measurement into a tune feedback system for RHIC 2001. Tune feedback is useful in a superconducting accelerator, where the machine cycle time is long and inefficient acceleration due to resonance crossing is not comfortably tolerated. This is particularly true with the higher beam intensities planned for RHIC 2001. We present descriptions of a PLL tune measurement system implemented in the DSP/FPGA environment of a RHIC BPM electronics module and the feedback system into which the measurement is incorporated to regulate tune. In addition, we present results from the commissioning of this system during RHIC 2001.

  12. Climate forcings and feedbacks

    NASA Technical Reports Server (NTRS)

    Hansen, James

    1993-01-01

    Global temperature has increased significantly during the past century. Understanding the causes of observed global temperature change is impossible in the absence of adequate monitoring of changes in global climate forcings and radiative feedbacks. Climate forcings are changes imposed on the planet's energy balance, such as change of incoming sunlight or a human-induced change of surface properties due to deforestation. Radiative feedbacks are radiative changes induced by climate change, such as alteration of cloud properties or the extent of sea ice. Monitoring of global climate forcings and feedbacks, if sufficiently precise and long-term, can provide a very strong constraint on interpretation of observed temperature change. Such monitoring is essential to eliminate uncertainties about the relative importance of various climate change mechanisms including tropospheric sulfate aerosols from burning of coal and oil smoke from slash and burn agriculture, changes of solar irradiance changes of several greenhouse gases, and many other mechanisms. The considerable variability of observed temperature, together with evidence that a substantial portion of this variability is unforced indicates that observations of climate forcings and feedbacks must be continued for decades. Since the climate system responds to the time integral of the forcing, a further requirement is that the observations be carried out continuously. However, precise observations of forcings and feedbacks will also be able to provide valuable conclusions on shorter time scales. For example, knowledge of the climate forcing by increasing CFC's relative to the forcing by changing ozone is important to policymakers, as is information on the forcing by CO2 relative to the forcing by sulfate aerosols. It will also be possible to obtain valuable tests of climate models on short time scales, if there is precise monitoring of all forcings and feedbacks during and after events such as a large volcanic eruption

  13. Changing characteristics of arctic pressure ridges

    NASA Astrophysics Data System (ADS)

    Wadhams, Peter; Toberg, Nick

    2012-04-01

    The advent of multibeam sonar permits us to obtain full three-dimensional maps of the underside of sea ice. In particular this enables us to distinguish the morphological characteristics of first-year (FY) and multi-year (MY) pressure ridges in a statistically valid way, whereas in the past only a small number of ridges could be mapped laboriously by drilling. In this study pressure ridge distributions from two parts of the Arctic Ocean are compared, in both the cases using mainly data collected by the submarine “Tireless” in March 2007 during two specific grid surveys, in the Beaufort Sea at about 75° N, 140° W (N of Prudhoe Bay), and north of Ellesmere Island at about 83° 20‧ N, 64° W. In the Beaufort Sea the ice was mainly FY, and later melted or broke up as this area became ice-free during the subsequent summer. N of Ellesmere Island the ice was mainly MY. Ridge depth and spacing distributions were derived for each region using the boat's upward looking sonar, combined with distributions of shapes of the ridges encountered, using the Kongsberg EM3002 multibeam sonar. The differing shapes of FY and MY ridges are consistent with two later high-resolution multibeam studies of specific ridges by AUV. FY ridges are found to fit the normal triangular shape template in cross-section (with a range of slope angles averaging 27°) with a relatively constant along-crest depth, and often a structure of small ice blocks can be distinguished. MY ridges, however, are often split into a number of independent solid, smooth blocks of large size, giving an irregular ridge profile which may be seemingly without linearity. Our hypothesis for this difference is that during its long lifetime an MY ridge is subjected to several episodes of crack opening; new cracks in the Arctic pack often run in straight lines across the ridges and undeformed ice alike. Such a crack will open somewhat before refreezing, interpolating a stretch of thin ice into the structure, and breaking up

  14. Accountability and feedback, part IV: destructive feedback.

    PubMed

    Harolds, Jay A

    2013-04-01

    There are times that feedback is destructive rather than helpful to the employee and the organization. Occasionally, this is deliberate, such as when a boss does not like someone for reasons that have nothing to do with his/her performance as an employee, or his/her character. More often, it is inadvertent. This could be due to erroneous information from others or the leader's failure to take the time to adequately observe or supervise others. It could also be due to a lack of understanding of the individual's communication style, or failure to take into account age, cultural, religious, or sex differences. This article addresses some of these issues and what to do about it.

  15. Polarization feedback laser stabilization

    DOEpatents

    Esherick, Peter; Owyoung, Adelbert

    1988-01-01

    A system for locking two Nd:YAG laser oscillators includes an optical path for feeding the output of one laser into the other with different polarizations. Elliptical polarization is incorporated into the optical path so that the change in polarization that occurs when the frequencies coincide may be detected to provide a feedback signal to control one laser relative to the other.

  16. Feedback and Job Satisfaction.

    ERIC Educational Resources Information Center

    Mangelsdorff, A. David

    The purpose of the study was to determine the effects of providing feedback (results of how frequently a variety of tasks had been performed) on the job satisfaction of Dental Therapy Assistants (DTA's) during the course of several levels of training, i.e., up to three months, four to nine months and 10 to 18 months. Trainees were predominantly…

  17. School Formative Feedback Systems

    ERIC Educational Resources Information Center

    Halverson, Richard

    2010-01-01

    Data-driven instructional improvement relies on developing coherent systems that allow school staff to generate, interpret, and act upon quality formative information on students and school programs. This article offers a formative feedback system model that captures how school leaders and teachers structure artifacts and practices to create…

  18. Real, Fast, Feedback

    ERIC Educational Resources Information Center

    Hill, Paul

    2013-01-01

    To better comprehend the needs of your clientele and colleagues, it is essential to use survey website applications. Doing so will help you become more efficient in obtaining constructive, timely feedback in order to adjust programming, therefore optimizing the impacts of Extension activities. Citing the most influential survey experts both in and…

  19. Feedback and Prior Achievement.

    ERIC Educational Resources Information Center

    Hyman, Cynthia; Tobias, Sigmund

    The hypothesis that feedback in programmed instruction is an important variable in the learning of novel, but not familiar, content was investigated. A linear, constructed response program dealing with the Sabbath rituals in the synagogue was chosen due to wide variability in student familiarity with this topic. Subjects were randomly assigned to…

  20. Review of Assessment Feedback

    ERIC Educational Resources Information Center

    Li, Jinrui; De Luca, Rosemary

    2014-01-01

    This article reviews 37 empirical studies, selected from 363 articles and 20 journals, on assessment feedback published between 2000 and 2011. The reviewed articles, many of which came out of studies in the UK and Australia, reflect the most current issues and developments in the area of assessing disciplinary writing. The article aims to outline…

  1. Feedback in Information Retrieval.

    ERIC Educational Resources Information Center

    Spink, Amanda; Losee, Robert M.

    1996-01-01

    As Information Retrieval (IR) has evolved, it has become a highly interactive process, rooted in cognitive and situational contexts. Consequently the traditional cybernetic-based IR model does not suffice for interactive IR or the human approach to IR. Reviews different views of feedback in IR and their relationship to cybernetic and social…

  2. Feedback: A Basic Ingredient

    ERIC Educational Resources Information Center

    Skenderis, Theodoros; Laskaridou, Chryssa

    2010-01-01

    The way we, teachers, talk to learners in general and, more specifically, the way we respond to what they have/haven't said or done affects them both as personalities and as learners. Even if we could agree that all teacher feedback is meant well, we could equally well agree that it does not always have the expected effects: learners do not always…

  3. Latent Fingerprint Matching: Performance Gain via Feedback from Exemplar Prints.

    PubMed

    Arora, Sunpreet S; Liu, Eryun; Cao, Kai; Jain, Anil K

    2014-12-01

    Latent fingerprints serve as an important source of forensic evidence in a court of law. Automatic matching of latent fingerprints to rolled/plain (exemplar) fingerprints with high accuracy is quite vital for such applications. However, latent impressions are typically of poor quality with complex background noise which makes feature extraction and matching of latents a significantly challenging problem. We propose incorporating top-down information or feedback from an exemplar to refine the features extracted from a latent for improving latent matching accuracy. The refined latent features (e.g. ridge orientation and frequency), after feedback, are used to re-match the latent to the top K candidate exemplars returned by the baseline matcher and resort the candidate list. The contributions of this research include: (i) devising systemic ways to use information in exemplars for latent feature refinement, (ii) developing a feedback paradigm which can be wrapped around any latent matcher for improving its matching performance, and (iii) determining when feedback is actually necessary to improve latent matching accuracy. Experimental results show that integrating the proposed feedback paradigm with a state-of-the-art latent matcher improves its identification accuracy by 0.5-3.5 percent for NIST SD27 and WVU latent databases against a background database of 100k exemplars.

  4. Latent Fingerprint Matching: Performance Gain via Feedback from Exemplar Prints.

    PubMed

    Arora, Sunpreet S; Liu, Eryun; Cao, Kai; Jain, Anil K

    2014-12-01

    Latent fingerprints serve as an important source of forensic evidence in a court of law. Automatic matching of latent fingerprints to rolled/plain (exemplar) fingerprints with high accuracy is quite vital for such applications. However, latent impressions are typically of poor quality with complex background noise which makes feature extraction and matching of latents a significantly challenging problem. We propose incorporating top-down information or feedback from an exemplar to refine the features extracted from a latent for improving latent matching accuracy. The refined latent features (e.g. ridge orientation and frequency), after feedback, are used to re-match the latent to the top K candidate exemplars returned by the baseline matcher and resort the candidate list. The contributions of this research include: (i) devising systemic ways to use information in exemplars for latent feature refinement, (ii) developing a feedback paradigm which can be wrapped around any latent matcher for improving its matching performance, and (iii) determining when feedback is actually necessary to improve latent matching accuracy. Experimental results show that integrating the proposed feedback paradigm with a state-of-the-art latent matcher improves its identification accuracy by 0.5-3.5 percent for NIST SD27 and WVU latent databases against a background database of 100k exemplars. PMID:26353151

  5. Trace elements in ocean ridge basalts

    NASA Technical Reports Server (NTRS)

    Kay, R. W.; Hubbard, N. J.

    1978-01-01

    A study is made of the trace elements found in ocean ridge basalts. General assumptions regarding melting behavior, trace element fractionation, and alteration effects are presented. Data on the trace elements are grouped according to refractory lithophile elements, refractory siderophile elements, and volatile metals. Variations in ocean ridge basalt chemistry are noted both for regional and temporal characteristics. Ocean ridge basalts are compared to other terrestrial basalts, such as those having La/Yb ratios greater than those of chondrites, and those having La/Yb ratios less than those of chondrites. It is found that (1) as compared to solar or chondrite ratios, ocean ridge basalts have low ratios of large, highly-charged elements to smaller less highly-charged elements, (2) ocean ridge basalts exhibit low ratios of volatile to nonvolatile elements, and (3) the transition metals Cr through Zn in ocean ridge basalts are not fractionated more than a factor of 2 or 3 from the chondritic abundance ratios.

  6. The Mid-Ocean Ridge

    SciTech Connect

    Macdonald, K.C. ); Fox, P.J. )

    1990-06-01

    The Mid-Ocean Ridge girdles the earth like the seam of a baseball. For more than 75,000 kilometers, this submerged range of razorback mountains--many higher than the greatest peaks on land--marks the restless boundary between continental plates. An analysis of this huge structure reveals a fascinating picture of how it is created by magma welling up as the plates pull apart. The paper discusses sea-floor spreading, the magma supply model, types of discontinuities, off-axis structures, small overlaps and DEVALs (slight DEViations in Axial Linearity), and aquatic life.

  7. Ridge effect and alignment phenomenon

    SciTech Connect

    Lokhtin, I. P. Managadze, A. K. Snigirev, A. M.

    2013-05-15

    It is assumed that the ridge effect observed by the CMS Collaboration in proton-proton collisions at the LHC and the phenomenon observed by the Pamir Collaboration in emulsion experiments with cosmic rays and characterized by the alignment of spots on a film is a manifestation of the same as-yet-unknown mechanism of the emergence of a coplanar structure of events. A large coplanar effect at the LHC in the region of forward rapidities is predicted on the basis of this hypothesis and an analysis of experimental data.

  8. Horizontal Ridge Augmentation with Piezoelectric Hinge-Assisted Ridge Split Technique in the Atrophic Posterior Mandible

    PubMed Central

    Cha, Min-Sang; Lee, Ji-Hye; Lee, Sang-Woon; Cho, Lee-Ra; Huh, Yoon-Hyuk; Lee, You-Sun

    2014-01-01

    Onlay bone grafting, guided bone regeneration, and alveolar ridge split technique are considered reliable bone augmentation methods on the horizontally atrophic alveolar ridge. Among these techniques, alveolar ridge split procedures are technique-sensitive and difficult to perform in the posterior mandible. This case report describes successful implant placement with the use of piezoelectric hinge-assisted ridge split technique in an atrophic posterior mandible. PMID:27489822

  9. Geo-Morphological Analyses of the Gakkel Ridge and the Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Dorschel, B.; Schlindwein, V. S. N.; Eagles, G.

    2014-12-01

    The Gakkel Ridge in the Arctic Ocean and the Southwest Indian Ridge in the Southwest Indian Ocean between Africa and Antarctica are ultraslow-spreading (<20 mm yr-1) mid ocean ridges. This type of mid ocean ridge has distinct geo-morphologies that are influenced by the slow rate of plate divergence and by mantle potential temperature, which control the processes (peridotite diapirism and intersticial melt migration) by which material rises to fill the space vacated by plate divergence. These ridges are characterised by non-orthogonal spreading. Transform faults, typical of faster spreading mid ocean ridges, are far less common at ultraslow spreading mid ocean ridges. Thus in return, detailed geo-statistical analyses of the geo-morphology of ultraslow-spreading mid ocean ridges can provide valuable information towards a better understanding of these slowest of spreading ridges. We have generated high resolution bathymetric grids for the Gakkel and Southwest Indian ridges based on high resolution multibeam echosounder data from various expeditions with RV Polarstern. On the basis of these grids, geo-statistical analyses allow for an assessment of the geo-morphological elements of the ridges on various scales. The results of these analyses show that, approximately 200 km long medium-scale sections of the ridges can be characterised by the lengths and orientations of the short-scale (hundreds of meters to tens of kilometres) ridges and troughs. The geomorphologies of short-scale ridges and troughs situated at the junctions between medium scale sections often exhibit a mixture of the geomorphological elements seen in the neighbouring sections. These geo-morphological patterns provide insights into the overall spreading-geometry along the Gakkel Ridge and the Southwest Indian Ridge.

  10. Reward feedback accelerates motor learning.

    PubMed

    Nikooyan, Ali A; Ahmed, Alaa A

    2015-01-15

    Recent findings have demonstrated that reward feedback alone can drive motor learning. However, it is not yet clear whether reward feedback alone can lead to learning when a perturbation is introduced abruptly, or how a reward gradient can modulate learning. In this study, we provide reward feedback that decays continuously with increasing error. We asked whether it is possible to learn an abrupt visuomotor rotation by reward alone, and if the learning process could be modulated by combining reward and sensory feedback and/or by using different reward landscapes. We designed a novel visuomotor learning protocol during which subjects experienced an abruptly introduced rotational perturbation. Subjects received either visual feedback or reward feedback, or a combination of the two. Two different reward landscapes, where the reward decayed either linearly or cubically with distance from the target, were tested. Results demonstrate that it is possible to learn from reward feedback alone and that the combination of reward and sensory feedback accelerates learning. An analysis of the underlying mechanisms reveals that although reward feedback alone does not allow for sensorimotor remapping, it can nonetheless lead to broad generalization, highlighting a dissociation between remapping and generalization. Also, the combination of reward and sensory feedback accelerates learning without compromising sensorimotor remapping. These findings suggest that the use of reward feedback is a promising approach to either supplement or substitute sensory feedback in the development of improved neurorehabilitation techniques. More generally, they point to an important role played by reward in the motor learning process.

  11. Feedback: Focusing Attention on Engagement

    ERIC Educational Resources Information Center

    Price, Margaret; Handley, Karen; Millar, Jill

    2011-01-01

    Within many higher education systems there is a search for means to increase levels of student satisfaction with assessment feedback. This article suggests that the search is under way in the wrong place by concentrating on feedback as a product rather than looking more widely to feedback as a long-term dialogic process in which all parties are…

  12. Engaging Students with Audio Feedback

    ERIC Educational Resources Information Center

    Cann, Alan

    2014-01-01

    Students express widespread dissatisfaction with academic feedback. Teaching staff perceive a frequent lack of student engagement with written feedback, much of which goes uncollected or unread. Published evidence shows that audio feedback is highly acceptable to students but is underused. This paper explores methods to produce and deliver audio…

  13. Feedback: Part of a System

    ERIC Educational Resources Information Center

    Wiliam, Dylan

    2012-01-01

    Just as a thermostat adjusts room temperature, effective feedback helps maintain a supportive environment for learning. Because of the many factors affecting how recipients respond to feedback, research offers no simple prescription for making feedback work effectively. What works in one classroom for one teacher will not work for another teacher.…

  14. How to Give Professional Feedback

    ERIC Educational Resources Information Center

    Brookhart, Susan M.; Moss, Connie M.

    2015-01-01

    Professional learning "should be a joy," the authors write, "not an affliction." Feedback experts Brookhart and Moss show how professional feedback can best motivate educators to learn. Professional conversations should be dialogs between the teacher and the principal, and feedback should feed teacher professional learning…

  15. DISTRIBUTED AMPLIFIER INCORPORATING FEEDBACK

    DOEpatents

    Bell, P.R. Jr.

    1958-10-21

    An improved distributed amplifier system employing feedback for stabilization is presented. In accordance with the disclosed invention, a signal to be amplified is applled to one end of a suitable terminated grid transmission line. At intervals along the transmission line, the signal is fed to stable, resistance-capacitance coupled amplifiers incorporating feedback loops therein. The output current from each amplifier is passed through an additional tube to minimize the electrostatic capacitance between the tube elements of the last stage of the amplifier, and fed to appropriate points on an output transmission line, similar to the grid line, but terminated at the opposite (input) end. The output taken from the unterminated end of the plate transmission line is proportional to the input voltage impressed upon the grid line.

  16. Polarization feedback laser stabilization

    DOEpatents

    Esherick, P.; Owyoung, A.

    1987-09-28

    A system for locking two Nd:YAG laser oscillators includes an optical path for feeding the output of one laser into the other with different polarizations. Elliptical polarization is incorporated into the optical path so that the change in polarization that occurs when the frequencies coincide may be detected to provide a feedback signal to control one laser relative to the other. 4 figs.

  17. Fiber distributed feedback laser

    NASA Technical Reports Server (NTRS)

    Elachi, C.; Evans, G. A.; Yeh, C. (Inventor)

    1976-01-01

    Utilizing round optical fibers as communication channels in optical communication networks presents the problem of obtaining a high efficiency coupling between the optical fiber and the laser. A laser is made an integral part of the optical fiber channel by either diffusing active material into the optical fiber or surrounding the optical fiber with the active material. Oscillation within the active medium to produce lasing action is established by grating the optical fiber so that distributed feedback occurs.

  18. Regenerative feedback resonant circuit

    DOEpatents

    Jones, A. Mark; Kelly, James F.; McCloy, John S.; McMakin, Douglas L.

    2014-09-02

    A regenerative feedback resonant circuit for measuring a transient response in a loop is disclosed. The circuit includes an amplifier for generating a signal in the loop. The circuit further includes a resonator having a resonant cavity and a material located within the cavity. The signal sent into the resonator produces a resonant frequency. A variation of the resonant frequency due to perturbations in electromagnetic properties of the material is measured.

  19. Emergency preparedness at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Skipper, M.N.

    1990-03-01

    Emergency preparedness for industry was commonly believed to be an essential responsibility on the part of management. Therefore, this study was conducted to research and accumulate information and data on emergency preparedness at Oak Ridge National Laboratory (ORNL). The objective of this study was to conduct a thorough evaluation of emergency preparedness knowledge among employees to determine if they were properly informed or if they needed more training. Also, this study was conducted to provide insight to management as to what their responsibility was concerning this training. To assess employee emergency preparedness knowledge, a questionnaire was developed and administered to 100 employees at ORNL. The data was analyzed using frequencies and percentages of response and was displayed through the use of graphs within the report. 22 refs., 22 figs.

  20. Feedback on Feedback: Eliciting Learners' Responses to Written Feedback through Student-Generated Screencasts

    ERIC Educational Resources Information Center

    Fernández-Toro, María; Furnborough, Concha

    2014-01-01

    Despite the potential benefits of assignment feedback, learners often fail to use it effectively. This study examines the ways in which adult distance learners engage with written feedback on one of their assignments. Participants were 10 undergraduates studying Spanish at the Open University, UK. Their responses to feedback were elicited by means…

  1. 27 CFR 9.182 - Ribbon Ridge.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) Approved Maps. The appropriate maps used to determine the boundaries of the Ribbon Ridge viticultural area are the following two United States Geological Survey (USGS), 1:24,000 scale, topographical maps (7.5..., Oregon, 1956, revised 1993. (c) Boundary. The Ribbon Ridge viticultural area is located in...

  2. Cedar Ridge Camp: Using the Local Environment

    ERIC Educational Resources Information Center

    Burke, Grayson

    2007-01-01

    In 2007 Cedar Ridge Camp opened for its first season as a traditional co-ed summer camp and year-round outdoor education and recreation centre. The mission would centre on creating a program that would encourage personal development and growth through a shared outdoor experience. Cedar Ridge's main goals were to promote the formation of close…

  3. Ridges and tidal stress on Io

    USGS Publications Warehouse

    Bart, G.D.; Turtle, E.P.; Jaeger, W.L.; Keszthelyi, L.P.; Greenberg, R.

    2004-01-01

    Sets of ridges of uncertain origin are seen in twenty-nine high-resolution Galileo images, which sample seven locales on Io. These ridges are on the order of a few kilometers in length with a spacing of about a kilometer. Within each locale, the ridges have a consistent orientation, but the orientations vary from place to place. We investigate whether these ridges could be a result of tidal flexing of Io by comparing their orientations with the peak tidal stress orientations at the same locations. We find that ridges grouped near the equator are aligned either north-south or east-west, as are the predicted principal stress orientations there. It is not clear why particular groups run north-south and others east-west. The one set of ridges observed far from the equator (52?? S) has an oblique azimuth, as do the tidal stresses at those latitudes. Therefore, all observed ridges have similar orientations to the tidal stress in their region. This correlation is consistent with the hypothesis that tidal flexing of Io plays an important role in ridge formation. ?? 2004 Elsevier Inc. All rights reserved.

  4. Transverse dune trailing ridges and vegetation succession

    NASA Astrophysics Data System (ADS)

    Hesp, Patrick A.; ‘Marisa' Martinez, M. L.

    2008-07-01

    We describe the evolution of, and vegetation succession on, a previously undescribed landform: transverse dune trailing ridges at El Farallón transgressive dunefield in the state of Veracruz, Mexico. Three-dimensional clinometer/compass and tape topographic surveys were conducted in conjunction with 1 m 2 contiguous percent cover and presence/absence vegetation survey transects at eight locations across two adjacent trailing ridges. At the study site, and elsewhere, the transverse dune trailing ridges are formed by vegetation colonization of the lateral margins of active transverse, barchanoidal transverse, and aklé or network dunes. For simplicity, all trailing ridges formed from these dune types are referred to as transverse dune trailing ridges. Because there are several transverse dunes in the dunefield, multiple trailing ridges can be formed at one time. Two adjacent trailing ridges were examined. The shortest length ridge was 70 m long, and evolving from a 2.5 m-high transverse dune, while the longer ridge was 140 m long, and evolving from an 8 m-high dune. Trailing ridge length is a proxy measure of ridge age, since the longer the ridge, the greater the length of time since initial formation. With increasing age or distance upwind, species diversity increased, as well as species horizontal extent and percent cover. In turn, the degree of bare sand decreased. Overall, the data indicate a successional trend in the vegetation presence and cover with increasing age upwind. Those species most tolerant to burial ( Croton and Palafoxia) begin the process of trailing ridge formation. Ipomoea and Canavalia are less tolerant to burial and also are typically the next colonizing species. Trachypogon does not tolerate sand burial or deposition very well and only appears after significant stabilization has taken place. The ridges display a moderately defined successional sequence in plant colonization and percentage cover with time (and upwind distance). They are

  5. Hydroforming Applications at Oak Ridge

    SciTech Connect

    bird, e.l.; ludtka, g.m.

    1999-03-10

    Hydroforming technology is a robust forming process that produces components with high precision and complexity. The goal of this paper is to present a brief description of the sheet hydroforming process with respect to the authors' experience and capabilities. Following the authors' discussion of the sheet-metal forming application, the tubular hydroforming process is described in the context of one of our technology development programs with an automotive industrial partner. After that is a summary of the tubular hydroforming advisor (expert system) development activity, which was a significant part of this overall program based on previous experience in developing a design and manufacturing support hydroforming advisor for the Oak Ridge Y-12 Plant's weapons-component manufacturing needs. Therefore, this paper is divided into three sections: (1) Hydroforming of Stainless Steel Parts, (2) Tubular Hydroforming, and (3) Components of a Tubular Hydroforming Advisor.

  6. Precipitation-Regulated Feedback

    NASA Astrophysics Data System (ADS)

    Voit, Mark

    2016-07-01

    Star formation in the central galaxies of galaxy clusters appears to be fueled by precipitation of cold clouds out of hot circumgalactic gas via thermal instability. I will present both observational and theoretical support for the precipitation mode in large galaxies and discuss how it can be implemented in cosmological simulations of galaxy evolution. Galaxy cluster cores are unique laboratories for studying the astrophysics of thermal instability and may be teaching us valuable lessons about how feedback works in galaxies spanning the entire mass spectrum.

  7. The "pressures" of being a ridge

    NASA Astrophysics Data System (ADS)

    Fleeman, K.; Scott, J. L.; Barton, M.

    2015-12-01

    As part of a larger project aimed at understanding the magma plumbing systems and magmatic processes responsible for crust formation at divergent plate margins, we have begun a study of the Galapagos Spreading Center (GSC), an intermediate spreading ridge off the west coast of South America and connected to the East Pacific Rise. This ridge is of interest because it passes close to the Galapagos Islands, allowing the effects of a mantle plume on sub-ridge processes and magma plumbing systems to be examined. In addition, the effects of ridge-ridge intersection, ridge propagation, and ridge offsets by transform faults on magma evolution can be examined. Published compositional data for glasses collected along the ridge were used to calculate pressures of partial crystallization and to examine variations in magma chemistry along the ridge. To aid interpretation of the results, the ridge was divided into 12 segments based on sample distribution and the occurrence of ridge offsets. Calculated pressures for most segments range from 100 and 300 MPa, and indicate depths of partial crystallization of ~3-9 km. This suggests that accretion occurs mostly near the base of the crust. However, the range of pressures for some segments is relatively large with maximum calculated values of 500-750 MPa. For example, near the major transform fault at ~85OW, the calculated maximum pressure is 741 MPa and the average pressure is ~ 300 MPa. We consider it unlikely that the calculated high pressures represent the true pressure of partial crystallization, and suggest that the compositions of some magmas result from processes other than simple crystallization. Correlations between Pressure and MgO, between Na2O and MgO, P2O5 and K2O, and between Na8 and longitude suggest that the processes operating beneath this ridge are complex. Near the transform fault for example, MgO vs Pressure shows a negative correlation with an R2 value of 0.546. Such trends are inconsistent with magma evolution

  8. Classification of the alveolar ridge width: implant-driven treatment considerations for the horizontally deficient alveolar ridges.

    PubMed

    Tolstunov, Len

    2014-07-01

    Among many techniques advocated for the horizontally deficient alveolar ridges, ridge-split has many advantages. Here, treatment management strategies of the horizontally collapsed ridges, especially the ridge-split approach, are discussed and a clinically relevant implant-driven classification of the alveolar ridge width is proposed, with the goal to assist an operator in choosing the proper bone augmentation technique. Comparison and advantages of two commonly used techniques, ridge-split and block bone graft, are presented.

  9. Torque feedback transmission

    SciTech Connect

    Whalen, B.L.

    1987-01-20

    This patent describes an infinitely variable transmission of inline configuration for interconnecting a primer mover with a load for clutch free operation in a range of speed including hydraulic neutral comprising: a. planetary gear train means having a ring gear, planetary gears supported by a planetary gear carrier, and a sun gear, the sun gear being connected mechanically to the load, output shaft means for joining the sun gear to the load; b. variable torque feedback means comprising (i) a variable displacement hydraulic motor whose rotor shaft is in line with the output shaft means and drivingly connected to the prime mover and the planetary gear carrier during the full range of operation of the transmission, and (ii) a fixed displacement hydraulic pump connected hydraulically to the motor, the rotor shaft of the pump being connected mechanically to the ring gear and being axially displaced from the output shaft means; c. means for adjusting the displacement volume within the hydraulic motor for controlling the torque feedback in the transmission to provide infinitely variable coupling between the prime mover and the load over the full range of the transmission including hydraulic neutral; d. a speed reducer between the primer mover and the motor rotor shaft and a speed multiplier between the sun gear and the load; and e. mechanical transmission assembly means between the speed multiplier and the load in line with the motor rotor shaft and the output shaft means for providing selection of drive, reverse, park, and neutral.

  10. Hydrothermal venting on the Juan de Fuca Ridge over the last 600,000 years

    NASA Astrophysics Data System (ADS)

    Costa, K.; McManus, J. F.; Winckler, G.; Huybers, P. J.; Langmuir, C. H.; Giosan, L.; Middleton, J. L.; Mukhopadhyay, S.

    2015-12-01

    Mid-ocean ridges provide a unique chemical, physical, and biological environment on the seafloor. They are a significant source of dissolved Fe, a critical micronutrient in the ocean, and they are a primary source of CO2 from the mantle, Earth's largest carbon reservoir. Although more than a hundred modern hydrothermal systems have been discovered, few records of their variation through geological time have been obtained. Sediments near ocean ridges hold the potential to provide such records, and here we investigate sediments near the Juan de Fuca Ridge through continuous XRF scans coupled with oxygen isotope temporal constraints to explore hydrothermal activity over the past 600,000 years. These are the first records over multiple glacial-interglacial cycles and permit investigation of potential feedbacks between glacial-interglacial climate change and hydrothermal activity. Today, hydrothermal activity on the Juan de Fuca Ridge is characterized by hydrothermal particles with high concentrations of Fe, Cu, and Zn (Feely et. al., 1987). Over longer time scales, Fe concentrations are positively correlated with Ti (r2≥0.75), so that the dominant variability in Fe is due to the input of lithogenic material. Additional Fe inputs from hydrothermal activity increase the Fe/Ti ratio above the lithogenic value of 11.7 wt%/wt%. Intense hydrothermal activity (Fe/Ti > 25 wt%/wt%) is observed on the Juan de Fuca Ridge from ~375-430ka, and less intense but still elevated hydrothermal activity (Fe/Ti > 17 wt%/wt%) recurs at near 100kyr cyclicity, from 80-120ka, 180-220ka, 290-330ka, and 470-520ka. These time periods correspond to times of sea level fall owing to expanding ice volume, supporting a link between sea level changes and ridge crest activity

  11. SRTM Anaglyph: Wheeler Ridge, California

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Wheeler Ridge and vicinity, California, is a site of major tectonic activity, both historically and over recent geologic time. The epicenter of the 7.5 magnitude Kern County earthquake occurred here on July 21,1952, and numerous geologic and topographic features indicate rapid geologic processes. The ridge itself (upper-right center) is a geologic fold that is growing out of the southern San Joaquin Valley. A prominent 'wind gap,' now used for passage of the California aquaduct (with the aid of a pumping station), is evidence that the ridge grew faster than tranversing streams could erode down. Nearby abrupt and/or landslid mountain fronts similarly indicate a vigorous tectonic setting here, just north of the San Andreas fault. The Interstate 5 freeway can be seen crossing agricultural fields on the right and entering the very rugged and steep Grapevine Canyon toward the bottom.

    This anaglyph was generated by first draping a Landsat satellite image over a preliminary topographic map from the Shuttle Radar Topography Mission (SRTM), then generating two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter. Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data matches the 30 meter resolution of most Landsat images and will substantially help in analyses of the large and growing Landsat image archive.

    The elevation data used in this image was acquired by SRTM aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect

  12. Feedback control of waiting times

    NASA Astrophysics Data System (ADS)

    Brandes, Tobias; Emary, Clive

    2016-04-01

    Feedback loops are known as a versatile tool for controlling transport in small systems, which usually have large intrinsic fluctuations. Here we investigate the control of a temporal correlation function, the waiting-time distribution, under active and passive feedback conditions. We develop a general formalism and then specify to the simple unidirectional transport model, where we compare costs of open-loop and feedback control and use methods from optimal control theory to optimize waiting-time distributions.

  13. The structure of mid-ocean ridges

    NASA Technical Reports Server (NTRS)

    Solomon, Sean C.; Toomey, Douglas R.

    1992-01-01

    Recent research results on the structure of midocean ridges are reviewed. The new view of ridge-axis crustal structure obtained from high-resolution seismology is reviewed, emphasizing the variation of that structure with spreading rate and along-axis at a given spreading rate. Recent results on upper mantle structure beneath ridges are examined, including variations with seafloor age, indications from anisotropy for directions of mantle flow, and long-wavelength along-axis variations in structure and their implications for lateral heterogeneity in mantle temperature and composition.

  14. Fast feedback for linear colliders

    SciTech Connect

    Hendrickson, L.; Adolphsen, C.; Allison, S.; Gromme, T.; Grossberg, P.; Himel, T.; Krauter, K.; MacKenzie, R.; Minty, M.; Sass, R.

    1995-05-01

    A fast feedback system provides beam stabilization for the SLC. As the SLC is in some sense a prototype for future linear colliders, this system may be a prototype for future feedbacks. The SLC provides a good base of experience for feedback requirements and capabilities as well as a testing ground for performance characteristics. The feedback system controls a wide variety of machine parameters throughout the SLC and associated experiments, including regulation of beam position, angle, energy, intensity and timing parameters. The design and applications of the system are described, in addition to results of recent performance studies.

  15. Controls on melting at spreading ridges from correlated abyssal peridotite - mid-ocean ridge basalt compositions

    NASA Astrophysics Data System (ADS)

    Regelous, Marcel; Weinzierl, Christoph G.; Haase, Karsten M.

    2016-09-01

    Variations in the volume and major element composition of basalt erupted along the global mid-ocean ridge system have been attributed to differences in mantle potential temperature, mantle composition, or plate spreading rate and lithosphere thickness. Abyssal peridotites, the residues of mantle melting beneath mid-ocean ridges, provide additional information on the melting process, which could be used to test these hypotheses. We compiled a global database of abyssal peridotite compositions averaged over the same ridge segments defined by Gale et al. (2013). In addition, we calculated the distance of each ridge segment to the nearest hotspots. We show that Cr# in spinel in abyssal peridotites is negatively correlated with Na90 in basalts from the same ridge segments on a global scale. Ridge segments that erupt basalts apparently produced by larger degrees of mantle melting are thus underlain by peridotites from which large amounts of melt have been extracted. We find that near-ridge hotspots have a more widespread influence on mid-ocean ridge basalt (MORB) composition and ridge depth than previously thought. However, when these hotspot-influenced ridge segments are excluded, the remaining segments show clear relationships between MORB composition, peridotite composition, and ridge depth with spreading rate. Very slow-spreading ridges (<20 mm/yr) are deeper, erupt basalts with higher Na90, Al90, K90/Ti90, and lower Fe90, Ca90/Al90, and expose peridotites with lower Cr# than intermediate and fast-spreading ridges. We show that away from hotspots, the spreading-rate dependence of the maximum degree of mantle melting inferred from Cr# in peridotites (FM) and the bulk degree of melting inferred from Na90 in basalts (FB) from the same ridge segments is unlikely to be due to variations in mantle composition. Nor can the effects of dynamic mantle upwelling or incomplete melt extraction at low spreading rates satisfactorily explain the observed compositions of abyssal

  16. Periodic bedrock ridges on Mars

    NASA Astrophysics Data System (ADS)

    Montgomery, David R.; Bandfield, Joshua L.; Becker, Scott K.

    2012-03-01

    Evidence for sediment transport and erosion by wind is widespread over the surface of Mars today and was likely a major geomorphic process for much of its geological past. Although Martian surface features resembling aeolian dunes and ripples have been recognized since the Mariner and Viking missions, such features have been interpreted previously as active, indurated, or exhumed sedimentary forms. Here we report evidence based on High Resolution Imaging Science Experiment images that show some megaripple forms are eroded into cohesive substrate rather than being composed of loose granular material or fossilized dunes. Exposure of stratigraphic continuity within layered, cohesive material extending crest to trough through features with mean wavelengths of 18 to 51 m demonstrates the primarily erosional formation of what we term periodic bedrock ridges (PBRs). Hence some surfaces on Mars previously considered to be covered by wind-deposited material are actually wind-carved exposures that offer windows into Martian history. PBRs lack the distinctive streamlining associated with wind-parallel yardangs and comparison of PBR orientation to yardangs, megayardangs, and active sedimentary dunes in the same vicinity confirm that these PBRs formed transverse to prevailing winds. Observed wavelengths of PBRs are comparable to those predicted by a simple model for erosional wavelengths of periodic transverse bed forms owing to the spacing of flow separations within the flow. Recognition of these transverse aeolian erosional forms brings up the question of how widespread Martian PBRs are and how many have been misinterpreted as active or indurated (fossilized) sedimentary dunes.

  17. Quantum Feedback Amplification

    NASA Astrophysics Data System (ADS)

    Yamamoto, Naoki

    2016-04-01

    Quantum amplification is essential for various quantum technologies such as communication and weak-signal detection. However, its practical use is still limited due to inevitable device fragility that brings about distortion in the output signal or state. This paper presents a general theory that solves this critical issue. The key idea is simple and easy to implement: just a passive feedback of the amplifier's auxiliary mode, which is usually thrown away. In fact, this scheme makes the controlled amplifier significantly robust, and furthermore it realizes the minimum-noise amplification even under realistic imperfections. Hence, the presented theory enables the quantum amplification to be implemented at a practical level. Also, a nondegenerate parametric amplifier subjected to a special detuning is proposed to show that, additionally, it has a broadband nature.

  18. Feedback control of canards

    NASA Astrophysics Data System (ADS)

    Durham, Joseph; Moehlis, Jeff

    2008-03-01

    We present a control mechanism for tuning a fast-slow dynamical system undergoing a supercritical Hopf bifurcation to be in the canard regime, the tiny parameter window between small and large periodic behavior. Our control strategy uses continuous feedback control via a slow control variable to cause the system to drift on average toward canard orbits. We apply this to tune the FitzHugh-Nagumo model to produce maximal canard orbits. When the controller is improperly configured, periodic or chaotic mixed-mode oscillations are found. We also investigate the effects of noise on this control mechanism. Finally, we demonstrate that a sensor tuned in this way to operate near the canard regime can detect tiny changes in system parameters.

  19. Signatures of AGN feedback

    NASA Astrophysics Data System (ADS)

    Wylezalek, D.; Zakamska, N.

    2016-06-01

    Feedback from active galactic nuclei (AGN) is widely considered to be the main driver in regulating the growth of massive galaxies. It operates by either heating or driving the gas that would otherwise be available for star formation out of the galaxy, preventing further increase in stellar mass. Observational proof for this scenario has, however, been hard to come by. We have assembled a large sample of 133 radio-quiet type-2 and red AGN at 0.1100 M_{⊙} yr^{-1} where presumably the coupling of the AGN-driven wind to the gas is strongest. This observation is consistent with the AGN having a net suppression, or `negative' impact, through feedback on the galaxies' star formation history.

  20. Carlsberg Ridge and Mid-Atlantic Ridge: Comparison of slow spreading centre analogues

    NASA Astrophysics Data System (ADS)

    Murton, Bramley J.; Rona, Peter A.

    2015-11-01

    Eighty per cent of all mid-ocean spreading centres are slow. Using a mixture of global bathymetry data and ship-board multibeam echosounder data, we explore the morphology of global mid-ocean ridges and compare two slow spreading analogues: the Carlsberg Ridge in the north-west Indian Ocean between 57°E and 60°E, and the Kane to Atlantis super-segment of the Mid-Atlantic Ridge between 21°N and 31°N. At a global scale, mid-ocean spreading centres show an inverse correlation between segment length and spreading rate with segmentation frequency. Within this context, both the Mid-Atlantic Ridge super-segment and Carlsberg Ridge are similar: spreading at 22 and 26 mm/yr full rates respectively, being devoid of major transform faults, and being segmented by dextral, non-transform, second-order discontinuities. For these and other slow spreading ridges, we show that segmentation frequency varies inversely with flank height and ridge axis depth. Segments on both the Mid-Atlantic Ridge super-segment and Carlsberg Ridge range in aspect ratio (ridge flank height/axis width), depth and symmetry. Segments with high aspect ratios and deeper axial floors often have asymmetric rift flanks and are associated with indicators of lower degrees of melt flux. Segments with low aspect ratios have shallower axial floors, symmetric rift flanks, and evidence of robust melt supply. The relationship between segmentation, spreading rate, ridge depth and morphology, at both a global and local scale, is evidence that rates of melting of the underlying mantle and melt delivery to the crust play a significant role in determining the structure and morphology of slow spreading mid-ocean ridges.

  1. 27 CFR 9.182 - Ribbon Ridge.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ..., Oregon, 1956, revised 1993. (c) Boundary. The Ribbon Ridge viticultural area is located in northern... Quadrangle map at the intersection of a light-duty road known locally as Albertson Road and Dopp Road...

  2. 27 CFR 9.182 - Ribbon Ridge.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., Oregon, 1956, revised 1993. (c) Boundary. The Ribbon Ridge viticultural area is located in northern... Quadrangle map at the intersection of a light-duty road known locally as Albertson Road and Dopp Road...

  3. 27 CFR 9.182 - Ribbon Ridge.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., Oregon, 1956, revised 1993. (c) Boundary. The Ribbon Ridge viticultural area is located in northern... Quadrangle map at the intersection of a light-duty road known locally as Albertson Road and Dopp Road...

  4. 27 CFR 9.182 - Ribbon Ridge.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., Oregon, 1956, revised 1993. (c) Boundary. The Ribbon Ridge viticultural area is located in northern... Quadrangle map at the intersection of a light-duty road known locally as Albertson Road and Dopp Road...

  5. Stratigraphic evolution of Blake Outer Ridge

    SciTech Connect

    Markl, R.G.; Bryan, G.M.

    1983-04-01

    Multichannel seismic data from a reconnaissance survey of the Blake Outer Ridge reveal the seismic stratigraphy down to oceanic basement, as well as intracrustal and mantle reflections. The depositional history of the outer ridge can now be subdivided into four principal phases, based on seismic stratigraphic style: (1) Jurassic-Early Cretaceous sedimentation which filled in basement irregularities and leveled the sea floor by horizon ..beta.. (Barremian) time, (2) Early Cretaceous-Late Cretaceous deposition of a seaward-thinning wedge typical of Atlantic-type margins; its deeply eroded surface is probably equivalent to the Late Cretaceous-Miocene hiatus reflected by horizon A'', (3) earlies Miocene current-controlled deposits preferentially deposited along the axis of the incipient Blake Outer Ridge; these prograding strata, which thin and dip downridge and laterally away from the ridge axis, are attributed to the interaction of the Florida Current and Western Boundary Undercurrent, and (4) continuing early Miocene preferential deposition on the ridge axis and sculpting by the Western Boundary Undercurrent; this phase is characterized by strata thinning and dipping upridge and toward the ridge axis. The reversal of dip is explained to a first approximation by a steady-state contour-current model in which the current position is progressively shifted by the deposition. Five angular unconformities and associated bathymetric terraces west of the ridge crest are mapped using all Lamont-Doherty seismic data and interpreted as having formed penecontemporaneously during phase four. The areal extent of the gas hydrate (clathrate) horizon is also delineated; it is continuous across the northern Blake Outer Ridge, and the multichannel seismic data presented here show it to extend onto the shallow Blake Plateau as well.

  6. Dark and Bright Ridges on Europa

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This high-resolution image of Jupiter's moon Europa, taken by NASA's Galileo spacecraft camera, shows dark, relatively smooth region at the lower right hand corner of the image which may be a place where warm ice has welled up from below. The region is approximately 30 square kilometers in area. An isolated bright hill stands within it. The image also shows two prominent ridges which have different characteristics; youngest ridge runs from left to top right and is about 5 kilometers in width (about 3.1 miles). The ridge has two bright, raised rims and a central valley. The rims of the ridge are rough in texture. The inner and outer walls show bright and dark debris streaming downslope, some of it forming broad fans. This ridge overlies and therefore must be younger than a second ridge running from top to bottom on the left side of the image. This dark 2 km wide ridge is relatively flat, and has smaller-scale ridges and troughs along its length.

    North is to the top of the picture, and the sun illuminates the surface from the upper left. This image, centered at approximately 14 degrees south latitude and 194 degrees west longitude, covers an area approximately 15 kilometers by 20 kilometers (9 miles by 12 miles). The resolution is 26 meters (85 feet) per picture element. This image was taken on December 16, 1997 at a range of 1300 kilometers (800 miles) by Galileo's solid state imaging system.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

  7. Realization of Ridge Regression in MATLAB

    NASA Astrophysics Data System (ADS)

    Dimitrov, S.; Kovacheva, S.; Prodanova, K.

    2008-10-01

    The least square estimator (LSE) of the coefficients in the classical linear regression models is unbiased. In the case of multicollinearity of the vectors of design matrix, LSE has very big variance, i.e., the estimator is unstable. A more stable estimator (but biased) can be constructed using ridge-estimator (RE). In this paper the basic methods of obtaining of Ridge-estimators and numerical procedures of its realization in MATLAB are considered. An application to Pharmacokinetics problem is considered.

  8. Assessing the clarity of friction ridge impressions.

    PubMed

    Hicklin, R Austin; Buscaglia, JoAnn; Roberts, Maria Antonia

    2013-03-10

    The ability of friction ridge examiners to correctly discern and make use of the ridges and associated features in finger or palm impressions is limited by clarity. The clarity of an impression relates to the examiner's confidence that the presence, absence, and attributes of features can be correctly discerned. Despite the importance of clarity in the examination process, there have not previously been standard methods for assessing clarity in friction ridge impressions. We introduce a process for annotation, analysis, and interchange of friction ridge clarity information that can be applied to latent or exemplar impressions. This paper: (1) describes a method for evaluating the clarity of friction ridge impressions by using color-coded annotations that can be used by examiners or automated systems; (2) discusses algorithms for overall clarity metrics based on manual or automated clarity annotation; and (3) defines a method of quantifying the correspondence of clarity when comparing a pair of friction ridge images, based on clarity annotation and resulting metrics. Different uses of this approach include examiner interchange of data, quality assurance, metrics, and as an aid in automated fingerprint matching. PMID:23313600

  9. Oak Ridge Reservation environmental report for 1989

    SciTech Connect

    Jacobs, V.A.; Wilson, A.R.

    1990-10-01

    This two-volume report, the Oak Ridge Reservation Environmental Report for 1989, is the nineteenth in an annual series that began in 1971. It reports the results of a comprehensive, year-round program to monitor the impact of operations at the three major US Department of Energy (DOE) production and research installations in Oak Ridge on the immediate areas' and surrounding region's groundwater and surface waters, soil, air quality, vegetation and wildlife, and through these multiple and varied pathways, the resident human population. Information is presented for the environmental monitoring Quality Assurance (QA) Program, audits and reviews, waste management activities, land special environmental studies. Data are included for the Oak Ridge Y-12 Plant, Oak Ridge National Laboratory (ORNL), and Oak Ridge Gaseous Diffusion Plant (ORGDP). Volume 1 presents narratives, summaries, and conclusions based on environmental monitoring at the three DOE installations and in the surrounding environs during calendar year (CY) 1989. Volume 1 is intended to be a stand-alone'' report about the Oak Ridge Reservation (ORR) for the reader who does not want an in-depth review of 1989 data. Volume 2 presents the detailed data from which these conclusions have been drawn and should be used in conjunction with Volume 1.

  10. Fast Feedback in Classroom Practice

    ERIC Educational Resources Information Center

    Emmett, Katrina; Klaassen, Kees; Eijkelhof, Harrie

    2009-01-01

    In this article we describe one application of the fast feedback method (see Berg 2003 "Aust. Sci. Teach. J." 28-34) in secondary mechanics education. Two teachers tried out a particular sequence twice, in consecutive years, once with and once without the use of fast feedback. We found the method to be successful, and the data that we obtained…

  11. Using Computer Networking for Feedback.

    ERIC Educational Resources Information Center

    Woodward, John; And Others

    1987-01-01

    Two studies involving 27 learning-disabled middle-school students and 30 mildly handicapped junior high students investigated use of Teacher Net, a computer networking system that facilitates immediate feedback. Teacher Net reduced the teachers' administrative workload, effectively monitored student understanding, provided feedback to teachers,…

  12. Feedback in sequential machine realizations.

    NASA Technical Reports Server (NTRS)

    Harlow, C. A.; Coates, C. L., Jr.

    1972-01-01

    A method is described for determining the realizability of a sequential machine with trigger or set-reset flip-flop memory elements when the feedback of the machine is given by a Boolean function. Feedbacks in several types of sequential machines with different memory elements are compared, showing the memory specifications allowing the realization of such machines.

  13. Feedback Systems for Linear Colliders

    SciTech Connect

    1999-04-12

    Feedback systems are essential for stable operation of a linear collider, providing a cost-effective method for relaxing tight tolerances. In the Stanford Linear Collider (SLC), feedback controls beam parameters such as trajectory, energy, and intensity throughout the accelerator. A novel dithering optimization system which adjusts final focus parameters to maximize luminosity contributed to achieving record performance in the 1997-98 run. Performance limitations of the steering feedback have been investigated, and improvements have been made. For the Next Linear Collider (NLC), extensive feedback systems are planned as an integral part of the design. Feedback requirements for JLC (the Japanese Linear Collider) are essentially identical to NLC; some of the TESLA requirements are similar but there are significant differences. For NLC, algorithms which incorporate improvements upon the SLC implementation are being prototyped. Specialized systems for the damping rings, rf and interaction point will operate at high bandwidth and fast response. To correct for the motion of individual bunches within a train, both feedforward and feedback systems are planned. SLC experience has shown that feedback systems are an invaluable operational tool for decoupling systems, allowing precision tuning, and providing pulse-to-pulse diagnostics. Feedback systems for the NLC will incorporate the key SLC features and the benefits of advancing technologies.

  14. Fine-Tuning Corrective Feedback.

    ERIC Educational Resources Information Center

    Han, ZhaoHong

    2001-01-01

    Explores the notion of "fine-tuning" in connection with the corrective feedback process. Describes a longitudinal case study, conducted in the context of Norwegian as a second a language, that shows how fine-tuning and lack thereof in the provision of written corrective feedback differentially affects a second language learner's restructuring of…

  15. Student Interpretations of Diagnostic Feedback

    ERIC Educational Resources Information Center

    Doe, Christine

    2015-01-01

    Diagnostic assessment is increasingly being recognized as a potentially beneficial tool for teaching and learning (Jang, 2012). There have been calls in the research literature for students to receive diagnostic feedback and for researchers to investigate how such feedback is used by students. Therefore, this study examined how students…

  16. Children's Reasoning about Evaluative Feedback

    ERIC Educational Resources Information Center

    Heyman, Gail D.; Fu, Genyue; Sweet, Monica A.; Lee, Kang

    2009-01-01

    Children's reasoning about the willingness of peers to convey accurate positive and negative performance feedback to others was investigated among a total of 179 6- to 11-year-olds from the USA and China. In Study 1, which was conducted in the USA only, participants responded that peers would be more likely to provide positive feedback than…

  17. Research on output feedback control

    NASA Technical Reports Server (NTRS)

    Calise, Anthony J.

    1988-01-01

    A summary is presented of the main results obtained during the course of research on output feedback control. The term output feedback is used to denote a controller design approach which does not rely on an observer to estimate the states of the system. Thus, the order of the controller is fixed, and can even be zero order, which amounts to constant gain ouput feedback. The emphasis has been on optimal output feedback. That is, a fixed order controller is designed based on minimizing a suitably chosen quadratic performance index. A number of problem areas that arise in this context have been addressed. These include developing suitable methods for selecting an index of performance, both time domain and frequency domain methods for achieving robustness of the closed loop system, developing canonical forms to achieve a minimal parameterization for the controller, two time scale design formulations for ill-conditioned systems, and the development of convergent numerical algorithms for solving the output feedback problem.

  18. Feedback: Implications for Further Research and Study.

    ERIC Educational Resources Information Center

    Nishikawa, Sue S.

    This report reviews current literature on feedback and suggests practical implications of feedback research for educators. A definition of feedback is offered, and past definitions in prior research are noted. An analysis of the current state of knowledge of feedback discusses the historical development of feedback theory and suggests that…

  19. Moving Feedback Forward: Theory to Practice

    ERIC Educational Resources Information Center

    Orsmond, Paul; Maw, Stephen J.; Park, Julian R.; Gomez, Stephen; Crook, Anne C.

    2013-01-01

    There is substantial research interest in tutor feedback and students' perception and use of such feedback. This paper considers some of the major issues raised in relation to tutor feedback and student learning. We explore some of the current feedback drivers, most notably the need for feedback to move away from simply a monologue from a tutor to…

  20. Understanding Feedback: A Learning Theory Perspective

    ERIC Educational Resources Information Center

    Thurlings, Marieke; Vermeulen, Marjan; Bastiaens, Theo; Stijnen, Sjef

    2013-01-01

    This article aims to review literature on feedback to teachers. Because research has hardly focused on feedback among teachers, the review's scope also includes feedback in classrooms. The review proposes that the effectiveness of feedback and feedback processes depend on the learning theory adhered to. Findings show that regardless of the…

  1. Attributes of an Effective Feedback Process

    ERIC Educational Resources Information Center

    Journal of Staff Development, 2015

    2015-01-01

    Not all feedback is created equal. It is actually quite uneven in its design and effectiveness. Feedback forms typically used by educators and the feedback process used to support learning have markedly different attributes. Understanding the key attributes of effective feedback is important for those involved in the feedback process. The tools…

  2. Feedback control of sound

    NASA Astrophysics Data System (ADS)

    Rafaely, Boaz

    This thesis is concerned with the development an application of feedback control techniques for active sound control. Both fixed and adaptive controllers are considered. The controller design problem for active sound control is formulated as a constrained optimisation problem with an H2 performance objective, of minimising the variance of the control error, and H2 and H∞ design constraints involving control power output, disturbance enhancement, and robust stability. An Internal Model Controller with an FIR control filter is assumed. Conventional H2 design methods for feedback controllers are studied first. Although such controllers can satisfy the design constraints by employing effort terms in the quadratic cost function, they do not achieve the best possible performance, and when adapted using LMS-based algorithms, they suffer from instabilities if the plant response varies significantly. Improved H2/H∞ design methods for fixed and adaptive controllers are then developed, which achieve the best H2 performance under the design constraints, offer an improved stability when made adaptive, and in general outperform the conventional H2 controllers. The H2/H∞ design problems employ convex programming to ensure a unique solution. The Sequential Quadratic Programming methods is used for the off-line design of fixed controllers, and penalty and barrier function methods, together with frequency domain LMS-based algorithms are employed in the H2/H∞ adaptive controllers. The controllers studied and developed here were applied to three active sound control systems: a noise-reducing headset, an active headrest, and a sound radiating panel. The emphasis was put on developing control strategies that improve system performance. First, a high performance controller for the noise-reducing headset was implemented in real-time, which combines analogue and adaptive digital controllers, and can thus reject disturbances which has both broad-band and periodic components. Then

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  4. Anxiety and feedback negativity.

    PubMed

    Gu, Ruolei; Huang, Yu-Xia; Luo, Yue-Jia

    2010-09-01

    It has been suggested that anxious individuals are more prone to feel that negative outcomes are particularly extreme and to interpret ambiguous outcomes as negative compared to nonanxious individuals. Previous studies have demonstrated that the feedback negativity (FN) component of event-related brain potential (ERP) is sensitive to outcome evaluation and outcome expectancy. Hence, we predicted that the FN should be different between high trait-anxiety (HTA) and low trait-anxiety (LTA) individuals. To test our hypothesis, the ERPs were recorded during a simple monetary gambling task. The FN was measured as a difference wave created across conditions. We found that the amplitude of the FN indicating negative versus positive outcomes was significantly larger for LTA individuals compared to HTA individuals. However, there was no significant difference in the FN between groups in response to ambiguous versus positive outcomes. The results indicate that there is a relationship between the FN and individual differences in anxiety. We suggest that these results reflect the impact of anxiety on outcome expectation. Our results challenge the reinforcement learning theory of error-related negativity, which proposes that ERN and FN reflect the same cognitive process.

  5. Evaluation of differential shim rod worth measurements in the Oak Ridge Research Reactor

    SciTech Connect

    Bretscher, M.M.

    1987-01-01

    Reasonable agreement between calculated and measured differential shim rod worths in the Oak Ridge Research Reactor (ORR) has been achieved by taking into account the combined effects of negative reactivity contributions from changing fuel-moderator temperatures and of delayed photoneutrons. A method has been developed for extracting the asymptotic period from the shape of the initial portion of the measured time-dependent neutron flux profile following a positive reactivity insertion. In this region of the curve temperature-related reactivity feedback effects are negligibly small. Results obtained by applying this technique to differential shim rod worth measurements made in a wide variety of ORR cores are presented.

  6. Formation and stability of ridge-ridge-ridge triple junctions in rheologically realistic lithosphere model

    NASA Astrophysics Data System (ADS)

    Gerya, Taras; Burov, Evgueni

    2015-04-01

    -branch junction formation and evolution by using high-resolution 3D numerical mechanical experiments that take into account realistic thermo-rheological structure and rheology of the lithosphere. We find that two major types of quadruple and triple junctions are formed under bi-directional or multidirectional far-field stress field: (i) plate rifting junctions are formed by the initial plate fragmentation and can be subsequently re-arranged into (ii) oceanic spreading junctions controlled by the new oceanic crust accretion. In particular, we document initial formation and destabilization of quadruple R-R-R-R junctions as initial plate rifting structures under bi-directional extension. In most cases, quadruple plate rifting junctions rapidly (typically within 1-2 Myr) evolve towards formation of two diverging triple oceanic spreading junctions connected by a linear spreading center lengthening with time. This configuration remains stable over long time scales. However, under certain conditions, quadruple junctions may also remain relatively stable. Asymmetric stretching results in various configurations, for example formation of "T-junctions" with trans-extensional components and combination of fast and slow spreading ridges. Combined with plume impingement, this scenario evolves in realistic patterns closely resembling observed plate dynamics. In particular, opening of the Red Sea and of the Afar rift system find a logical explanation within a single model. Numerical experiments also suggest that several existing oceanic spreading junctions form as the result of plate motions rearrangements after which only one of two plates spreading along the ridge become subjected to bi-directional spreading.

  7. Magmatic and tectonic extension at the Chile Ridge: Evidence for mantle controls on ridge segmentation

    NASA Astrophysics Data System (ADS)

    Howell, Samuel M.; Ito, Garrett; Behn, Mark D.; Martinez, Fernando; Olive, Jean-Arthur; Escartín, Javier

    2016-06-01

    We use data from an extensive multibeam bathymetry survey of the Chile Ridge to study tectonomagmatic processes at the ridge axis. Specifically, we investigate how abyssal hills evolve from axial faults, how variations in magmatic extension influence morphology and faulting along the spreading axis, and how these variations correlate with ridge segmentation. The bathymetry data are used to estimate the fraction of plate separation accommodated by normal faulting, and the remaining fraction of extension, M, is attributed primarily to magmatic accretion. Results show that M ranges from 0.85 to 0.96, systematically increasing from first-order and second-order ridge segment offsets toward segment centers as the depth of ridge axis shoals relative to the flanking highs of the axial valley. Fault spacing, however, does not correlate with ridge geometry, morphology, or M along the Chile Ridge, which suggests the observed increase in tectonic strain toward segment ends is achieved through increased slip on approximately equally spaced faults. Variations in M along the segments follow variations in petrologic indicators of mantle melt fraction, both showing a preferred length scale of 50 ± 20 km that persists even along much longer ridge segments. In comparison, mean M and axial relief fail to show significant correlations with distance offsetting the segments. These two findings suggest a form of magmatic segmentation that is partially decoupled from the geometry of the plate boundary. We hypothesize this magmatic segmentation arises from cells of buoyantly upwelling mantle that influence tectonic segmentation from the mantle, up.

  8. Feedback systems in the SLC

    SciTech Connect

    Thompson, K.A.; Jobe, R.K.; Johnson, R.; Phinney, N.

    1987-02-01

    Two classes of computer-controlled feedback have been implemented to stabilize parameters in subsystems of the SLC: (1) ''slow'' (time scales approx. minutes) feedback, and (2) ''fast'', i.e., pulse-to-pulse, feedback. The slow loops run in a single FEEDBACK process in the SLC host VAX, which acquires signals and sets control parameters via communication with the database and the network of normal SLC microprocessors. Slow loops exist to stabilize beam energy and energy spread, beam position and angle, and timing of kicker magnets, and to compensate for changes in the phase length of the rf drive line. The fast loops run in dedicated microprocessors, and may sample and/or feedback on particular parameters as often as every pulse of the SLC beam. The first implementations of fast feedback are to control transverse beam blow-up and to stabilize the energy and energy spread of bunches going into the SLC arcs. The overall architecture of the feedback software and the operator interface for controlling loops are discussed.

  9. Feedback control indirect response models.

    PubMed

    Zhang, Yaping; D'Argenio, David Z

    2016-08-01

    A general framework is introduced for modeling pharmacodynamic processes that are subject to autoregulation, which combines the indirect response (IDR) model approach with methods from classical feedback control of engineered systems. The canonical IDR models are modified to incorporate linear combinations of feedback control terms related to the time course of the difference (the error signal) between the pharmacodynamic response and its basal value. Following the well-established approach of traditional engineering control theory, the proposed feedback control indirect response models incorporate terms proportional to the error signal itself, the integral of the error signal, the derivative of the error signal or combinations thereof. Simulations are presented to illustrate the types of responses produced by the proposed feedback control indirect response model framework, and to illustrate comparisons with other PK/PD modeling approaches incorporating feedback. In addition, four examples from literature are used to illustrate the implementation and applicability of the proposed feedback control framework. The examples reflect each of the four mechanisms of drug action as modeled by each of the four canonical IDR models and include: selective serotonin reuptake inhibitors and extracellular serotonin; histamine H2-receptor antagonists and gastric acid; growth hormone secretagogues and circulating growth hormone; β2-selective adrenergic agonists and potassium. The proposed feedback control indirect response approach may serve as an exploratory modeling tool and may provide a bridge for development of more mechanistic systems pharmacology models. PMID:27394724

  10. Global Orbit Feedback in RHIC

    SciTech Connect

    Minty, M.; Hulsart, R.; Marusic, A.; Michnoff, R.; Ptitsyn, V.; Robert-Demolaize, G.; Satogata, T.

    2010-05-23

    For improved reproducibility of good operating conditions and ramp commissioning efficiency, new dual-plane slow orbit feedback during the energy ramp was implemented during run-10 in the Relativistic Heavy Ion Collider (RHIC). The orbit feedback is based on steering the measured orbit, after subtraction of the dispersive component, to either a design orbit or to a previously saved reference orbit. Using multiple correctors and beam position monitors, an SVD-based algorithm is used for determination of the applied corrections. The online model is used as a basis for matrix computations. In this report we describe the feedback design, review the changes made to realize its implementation, and assess system performance.

  11. Balanced bridge feedback control system

    NASA Technical Reports Server (NTRS)

    Lurie, Boris J. (Inventor)

    1990-01-01

    In a system having a driver, a motor, and a mechanical plant, a multiloop feedback control apparatus for controlling the movement and/or positioning of a mechanical plant, the control apparatus has a first local bridge feedback loop for feeding back a signal representative of a selected ratio of voltage and current at the output driver, and a second bridge feedback loop for feeding back a signal representative of a selected ratio of force and velocity at the output of the motor. The control apparatus may further include an outer loop for feeding back a signal representing the angular velocity and/or position of the mechanical plant.

  12. Vertical Alveolar Ridge Augmentation by Distraction Osteogenesis

    PubMed Central

    Kumar, N. Nanda; Ravindran, C.

    2015-01-01

    Introduction Compromised alveolar ridge in vertical and horizontal dimension is a common finding in patients visiting practitioners for dental prosthesis. Various treatment modalities are available for correction of deficient ridges among which alveolar distraction osteogenesis is one. Aim To study the efficacy of alveolar distraction osteogenesis in augmentation of alveolar ridges deficient in vertical dimension. Materials and Methods Ten patients aged 16 to 46 years with deficient alveolar ridge underwent ridge augmentation in 11 alveolar segments using the distraction osteogenesis method. For each patient a custom made distraction device was fabricated. The device was indigenously manufactured with SS-316 (ISO 3506). Results The vertical bone gain reached more than 10mm without the use of bone transplantation. Certain complications like incorrect vector of distraction, paresthesia, pain and loss of transport segment were encountered during the course of the study. Conclusion Alveolar vertical distraction osteogenesis is a reliable and predictable technique for both hard and soft tissue genesis. Implant placement is feasible with primary stability in neogenerated bone at the level of the distracted areas. PMID:26816991

  13. Arctic Ocean: hydrothermal activity on Gakkel Ridge.

    PubMed

    Jean-Baptiste, Philippe; Fourré, Elise

    2004-03-01

    In the hydrothermal circulation at mid-ocean ridges, sea water penetrates the fractured crust, becomes heated by its proximity to the hot magma, and returns to the sea floor as hot fluids enriched in various chemical elements. In contradiction to earlier results that predict diminishing hydrothermal activity with decreasing spreading rate, a survey of the ultra-slowly spreading Gakkel Ridge (Arctic Ocean) by Edmonds et al. and Michael et al. suggests that, instead of being rare, the hydrothermal activity is abundant--exceeding by at least a factor of two to three what would be expected by extrapolation from observation on faster spreading ridges. Here we use helium-3 (3He), a hydrothermal tracer, to show that this abundance of venting sites does not translate, as would be expected, into an anomalous hydrothermal 3He output from the ridge. Because of the wide implications of the submarine hydrothermal processes for mantle heat and mass fluxes to the ocean, these conflicting results call for clarification of the link between hydrothermal activity and crustal production at mid-ocean ridges.

  14. Remedial Investigation Work Plan for Chestnut Ridge Operable Unit 1 (Chestnut Ridge Security Pits) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1994-03-01

    This document outlines the activities necessary to conduct a Remedial Investigation (RI) of the Chestnut Ridge Security Pits (CRSP) at the Oak Ridge Y-12 Plant. The CRSP, also designated Chestnut Ridge Operable Unit (OU) 1, is one of four OUs along Chestnut Ridge on the Oak Ridge Reservation (ORR). The purpose of the RI is to collect data to (1) evaluate the nature and extent of known and suspected contaminants, (2) support an Ecological Risk Assessment (ERA) and a Human Health Risk Assessment (HHRA), (3) support the feasibility study in the development and analysis of remedial alternatives, and (4) ultimately, develop a Record of Decision (ROD) for the site. This chapter summarizes the regulatory background of environmental investigation on the ORR and the approach currently being followed and provides an overview of the RI to be conducted at the CRSP. Subsequent chapters provide details on site history, sampling activities, procedures and methods, quality assurance (QA), health and safety, and waste management related to the RI.

  15. Modern therapy for severe alveolar ridge atrophy.

    PubMed

    Chen, Yu-Feng; Pan, Chin-Yun; Wang, Wen-Chen; Lan, Ting-Hsun

    2013-01-01

    This clinical report illustrates a modern method for oral rehabilitation of severe edentulous atrophic ridge. Shallow vestibule and small denture-bearing area of the maxilla provide insufficient retention, and only the symphyseal region of the mandible has obvious alveolar ridge. The surgery of deepening vestibule of the maxilla ridge was done by using tentative miniscrew combined with old denture and soft liner. The osseointegrated dental implants were installed over symphyseal region of the mandible to act as retentive devices for prostheses. In addition, functional reline with rebase material to build buccal-tongue contact over the retromolar area after denture delivery obtained high satisfaction from the patient. Many clinical conditions cannot be managed solely with implants or preprosthetic surgery alone, whereas a combination of the 2 can achieve successful outcome. PMID:24036818

  16. Innovation in healthcare team feedback.

    PubMed

    Plaza, Christine; Beard, Leslie; Fonzo, Anthony Di; Tommaso, Michael Di; Mujawaz, Yaman; Serra-Julia, Marcel; Morra, Dante

    2011-01-01

    Healthcare delivery is evolving from individual, autonomous practice to collaborative team practice. However, barriers such as professional autonomy, time constraints and the perception of error as failure preclude learning behaviours that can facilitate organizational learning and improvement. Although experimentation, engaging in questions and feedback, discussing errors and reflecting on results can facilitate learning and promote effective performance, the cultural barriers within healthcare can prevent or inhibit this type of behaviour among teams. At the University Health Network's Centre for Innovation in Complex Care, we realize the need for a tool that facilitates learning behaviour and is sensitive to the risk-averse nature of the clinical environment. The vehicle for the Team Feedback Tool is a web-based application called Rypple (www.rypple.com), which allows team members to provide anonymous, rapid-fire feedback on team processes and performance. Rypple facilitates communication, elicits feedback and provokes discussion. The process enables follow-up face-to-face team discussions and encourages teams to create actionable solutions for incremental changes to enhance team health and performance. The Team Feedback Tool was implemented and piloted in general internal medicine at the University Health Network's Toronto General Hospital from early May 2009 to July 2009 to address the issues of teamwork and learning behaviour in the clinical environment. This article explores the opportunities and barriers associated with the implementation of the Team Feedback Tool. PMID:21841396

  17. Feedback control of multibunch instabilities

    SciTech Connect

    Galayda, J. )

    1992-03-10

    This lecture is intended to be an introduction to the use of feedback control to counteract multibunch instabilities. Furthermore, the intent is to make the most direct connection possible between feedback system design and the linear equations of motion of a single particle in an accelerator. Descriptions of the electronic design and considerations of gain versus stability have been treated in the literature (1,2,3) and will be glossed over in this lecture. The exposition is aimed at an audience with reasonable background in linear charged particle optics and minimal familiarity with circuit theory and electronics design. We begin with a brief description of the sources of instability and a description of the function of a feedback system in terms of the equation of motion of a beam bunch. We will try to list the fundamentals of the design process of a feedback system in such a way as to give the reader a framework within which to evaluate the subsequent material. Section 2 develops simple definitions of feedback system performance parameters: damping time constant, gain, and power requirements. Sections 3 and 4 give a perspective on feedback signal processing, using several betatron damping systems to exemplify time domain signal processing. Section 5 views the signal processing problem in frequency domain, using the CERN PS Booster longitudinal damper as an example.

  18. Fluid venting and seepage at accretionary ridges: the Four Way Closure Ridge offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Klaucke, Ingo; Berndt, Christian; Crutchley, Gareth; Chi, Wu-Cheng; Lin, Saulwood; Muff, Sina

    2016-06-01

    Within the accretionary prism offshore SW Taiwan, widespread gas hydrate accumulations are postulated to occur based on the presence of a bottom simulating reflection. Methane seepage, however, is also widespread at accretionary ridges offshore SW Taiwan and may indicate a significant loss of methane bypassing the gas hydrate system. Four Way Closure Ridge, located in 1,500 m water depth, is an anticlinal ridge that would constitute an ideal trap for methane and consequently represents a site with good potential for gas hydrate accumulations. The analysis of high-resolution bathymetry, deep-towed sidescan sonar imagery, high-resolution seismic profiling and towed video observations of the seafloor shows that Four Way Closure Ridge is and has been a site of intensive methane seepage. Continuous seepage is mainly evidenced by large accumulations of authigenic carbonate precipitates, which appear to be controlled by the creation of fluid pathways through faulting. Consequently, Four Way Closure Ridge is not a closed system in terms of fluid migration and seepage. A conceptual model of the evolution of gas hydrates and seepage at accretionary ridges suggests that seepage is common and may be a standard feature during the geological development of ridges in accretionary prisms. The observation of seafloor seepage alone is therefore not a reliable indicator of exploitable gas hydrate accumulations at depth.

  19. The influence of ridge migration on the magmatic segmentation of mid-ocean ridges.

    PubMed

    Carbotte, S M; Small, C; Donnelly, K

    2004-06-17

    The Earth's mid-ocean ridges display systematic changes in depth and shape, which subdivide the ridges into discrete spreading segments bounded by transform faults and smaller non-transform offsets of the axis. These morphological changes have been attributed to spatial variations in the supply of magma from the mantle, although the origin of the variations is poorly understood. Here we show that magmatic segmentation of ridges with fast and intermediate spreading rates is directly related to the migration velocity of the spreading axis over the mantle. For over 9,500 km of mid-ocean ridge examined, leading ridge segments in the 'hotspot' reference frame coincide with the shallow magmatically robust segments across 86 per cent of all transform faults and 73 per cent of all second-order discontinuities. We attribute this relationship to asymmetric mantle upwelling and melt production due to ridge migration, with focusing of melt towards ridge segments across discontinuities. The model is consistent with variations in crustal structure across discontinuities of the East Pacific Rise, and may explain variations in depth of melting and the distribution of enriched lavas.

  20. Effects of invalid feedback on learning and feedback-related brain activity in decision-making.

    PubMed

    Ernst, Benjamin; Steinhauser, Marco

    2015-10-01

    For adaptive decision-making it is important to utilize only relevant, valid and to ignore irrelevant feedback. The present study investigated how feedback processing in decision-making is impaired when relevant feedback is combined with irrelevant and potentially invalid feedback. We analyzed two electrophysiological markers of feedback processing, the feedback-related negativity (FRN) and the P300, in a simple decision-making task, in which participants processed feedback stimuli consisting of relevant and irrelevant feedback provided by the color and meaning of a Stroop stimulus. We found that invalid, irrelevant feedback not only impaired learning, it also altered the amplitude of the P300 to relevant feedback, suggesting an interfering effect of irrelevant feedback on the processing of relevant feedback. In contrast, no such effect on the FRN was obtained. These results indicate that detrimental effects of invalid, irrelevant feedback result from failures of controlled feedback processing. PMID:26263382

  1. Normalization Ridge Regression in Practice I: Comparisons Between Ordinary Least Squares, Ridge Regression and Normalization Ridge Regression.

    ERIC Educational Resources Information Center

    Bulcock, J. W.

    The problem of model estimation when the data are collinear was examined. Though the ridge regression (RR) outperforms ordinary least squares (OLS) regression in the presence of acute multicollinearity, it is not a problem free technique for reducing the variance of the estimates. It is a stochastic procedure when it should be nonstochastic and it…

  2. Wrinkle Ridges and Young Fresh Crater

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 10 May 2002) The Science Wrinkle ridges are a very common landform on Mars, Mercury, Venus, and the Moon. These ridges are linear to arcuate asymmetric topographic highs commonly found on smooth plains. The origin of wrinkle ridges is not certain and two leading hypotheses have been put forth by scientists over the past 40 years. The volcanic model calls for the extrusion of high viscosity lavas along linear conduits. This thick lava accumulated over these conduits and formed the ridges. The other model is tectonic and advocates that the ridges are formed by compressional faulting and folding. Today's THEMIS image is of the ridged plains of Lunae Planum located between Kasei Valles and Valles Marineris in the northern hemisphere of the planet. Wrinkle ridges are found mostly along the eastern side of the image. The broadest wrinkle ridges in this image are up to 2 km wide. A 3 km diameter young fresh crater is located near the bottom of the image. The crater's ejecta blanket is also clearly seen surrounding the sharp well-defined crater rim. These features are indicative of a very young crater that has not been subjected to erosional processes. The Story The great thing about the solar system is that planets are both alike and different. They're all foreign enough to be mysterious and intriguing, and yet familiar enough to be seen as planetary 'cousins.' By comparing them, we can learn a lot about how planets form and then evolve geologically over time. Crinkled over smooth plains, the long, wavy raised landforms seen here are called 'wrinkle ridges,' and they've been found on Mars, Mercury, Venus, and the Moon - that is, on rocky bodies that are a part of our inner solar system. We know from this observation that planets (and large-enough moons) follow similar processes. What we don't know for sure is HOW these processes work. Scientists have been trying to understand how wrinkle ridges form for 40 years, and they still haven't reached a conclusion. That

  3. Audiotape Feedback for Essays in Distance Education.

    ERIC Educational Resources Information Center

    Kirschner, Paul A.; And Others

    1991-01-01

    Twelve students writing essays for a photochemistry course at the Open University of the Netherlands received either audiocasette or written feedback. Time spent in recording versus writing feedback differed minimally. Recorded feedback was considerably greater in amount. Students' final grades did not differ, but recorded feedback was more…

  4. Identifying Mentors' Observations for Providing Feedback

    ERIC Educational Resources Information Center

    Hudson, Peter

    2016-01-01

    Mentors' feedback can assist preservice teachers' development; yet feedback tends to be variable from one mentor to the next. What do mentors observe for providing feedback? In this study, 24 mentors observed a final-year preservice teacher through a professionally video-recorded lesson and provided written notes for feedback. They observed the…

  5. Feedback Revolution: What Gets in the Way?

    ERIC Educational Resources Information Center

    Lee, Icy

    2011-01-01

    Feedback in writing has in recent years attracted the attention of an increasing number of writing researchers. While much feedback research focuses on the act of feedback per se, little attention has been paid to the issue of teacher readiness to implement change in feedback. Using data gathered from Hong Kong secondary teachers attending a…

  6. A Comparison of Peer and Tutor Feedback

    ERIC Educational Resources Information Center

    Hamer, John; Purchase, Helen; Luxton-Reilly, Andrew; Denny, Paul

    2015-01-01

    We report on a study comparing peer feedback with feedback written by tutors on a large, undergraduate software engineering programming class. Feedback generated by peers is generally held to be of lower quality to feedback from experienced tutors, and this study sought to explore the extent and nature of this difference. We looked at how…

  7. Feedback as Real-Time Constructions

    ERIC Educational Resources Information Center

    Keiding, Tina Bering; Qvortrup, Ane

    2014-01-01

    This article offers a re-description of feedback and the significance of time in feedback constructions based on systems theory. It describes feedback as internal, real-time constructions in a learning system. From this perspective, feedback is neither immediate nor delayed, but occurs in the very moment it takes place. This article argues for a…

  8. Dynamics of Team Reflexivity after Feedback

    ERIC Educational Resources Information Center

    Gabelica, Catherine; Van den Bossche, Piet; Segers, Mien; Gijselaers, Wim

    2014-01-01

    A great deal of work has been generated on feedback in teams and has shown that giving performance feedback to teams is not sufficient to improve performance. To achieve the potential of feedback, it is stated that teams need to proactively process this feedback and thus collectively evaluate their performance and strategies, look for…

  9. Providing Students with Formative Audio Feedback

    ERIC Educational Resources Information Center

    Brearley, Francis Q.; Cullen, W. Rod

    2012-01-01

    The provision of timely and constructive feedback is increasingly challenging for busy academics. Ensuring effective student engagement with feedback is equally difficult. Increasingly, studies have explored provision of audio recorded feedback to enhance effectiveness and engagement with feedback. Few, if any, of these focus on purely formative…

  10. Ridge transform fault spreading pattern in freezing wax.

    PubMed

    Oldenburg, D W; Brune, J N

    1972-10-20

    A laboratory experiment shows that ridge-ridge transform faults, inactive fracture zones, and other features characteristic of spreading oceanic ridges can be produced in a variety of paraffins. Although the resultant pattern depends upon the temperature of the wax and the ratio of spreading rate to surface cooling, the characteristic orthogonal ridge transform fault system is a preferred mode of separation. Symmetric spreading occurs under conditions of no tensile strength across the ridge, and the stability of transform faults is a consequence of their lack of shear strength. The experiment also shows that properties characteristic of oceanic ridges occur under conditions of passive convection where upwelling of material at the ridge crest is a result only of hydrostatic forces in the fluid; that is, the plate separation is caused not by large convective forces beneath the ridge but rather by tensile forces in the plate. PMID:17735477

  11. Wrinkle Ridges in Aeolis Dorsa, Mars: Preliminary Mapping

    NASA Astrophysics Data System (ADS)

    Borden, R. M.; Burr, D. M.

    2016-06-01

    Previous work has interpreted wrinkle ridges as compressional landforms caused by movement along blind thrust faults. Our preliminary mapping in the Aeolis Dorsa, Mars has identified widely distributed wrinkle ridges, suggesting episodic contraction.

  12. 1. Building 8 south elevation oblique along Ridge Avenue. View ...

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

    1. Building 8 south elevation oblique along Ridge Avenue. View looking east. - John & James Dobson Carpet Mill (West Parcel), Building No. 8, 4041-4055 Ridge Avenue, Philadelphia, Philadelphia County, PA

  13. 1. Building 7 south elevation oblique along Ridge Avenue. View ...

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

    1. Building 7 south elevation oblique along Ridge Avenue. View looking east. - John & James Dobson Carpet Mill (West Parcel), Building No. 7, 4041-4055 Ridge Avenue, Philadelphia, Philadelphia County, PA

  14. 1. General view, corner of Ridge Avenue and Crawford Street. ...

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

    1. General view, corner of Ridge Avenue and Crawford Street. Building 10 shown center. View looking east. - John & James Dobson Carpet Mill (West Parcel), 4041-4055 Ridge Avenue, Philadelphia, Philadelphia County, PA

  15. Detail view of Bonita Ridge Access Road Retaining Wall showing ...

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

    Detail view of Bonita Ridge Access Road Retaining Wall showing drainpipes, camera facing northwest - Fort Barry, Bonita Ridge Access Road, Retaining Wall, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

  16. View of northern end of Bonita Ridge Access Road Retaining ...

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

    View of northern end of Bonita Ridge Access Road Retaining Wall, camera facing northwest - Fort Barry, Bonita Ridge Access Road, Retaining Wall, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

  17. Detail view of reinforced concrete of Bonita Ridge Access Road ...

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

    Detail view of reinforced concrete of Bonita Ridge Access Road Retaining Wall, camera facing northwest - Fort Barry, Bonita Ridge Access Road, Retaining Wall, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

  18. Oak Ridge reservation land-use plan

    SciTech Connect

    Bibb, W. R.; Hardin, T. H.; Hawkins, C. C.; Johnson, W. A.; Peitzsch, F. C.; Scott, T. H.; Theisen, M. R.; Tuck, S. C.

    1980-03-01

    This study establishes a basis for long-range land-use planning to accommodate both present and projected DOE program requirements in Oak Ridge. In addition to technological requirements, this land-use plan incorporates in-depth ecological concepts that recognize multiple uses of land as a viable option. Neither environmental research nor technological operations need to be mutually exclusive in all instances. Unique biological areas, as well as rare and endangered species, need to be protected, and human and environmental health and safety must be maintained. The plan is based on the concept that the primary use of DOE land resources must be to implement the overall DOE mission in Oak Ridge. This document, along with the base map and overlay maps, provides a reasonably detailed description of the DOE Oak Ridge land resources and of the current and potential uses of the land. A description of the land characteristics, including geomorphology, agricultural productivity and soils, water courses, vegetation, and terrestrial and aquatic animal habitats, is presented to serve as a resource document. Essentially all DOE land in the Oak Ridge area is being fully used for ongoing DOE programs or has been set aside as protected areas.

  19. Oak Ridge Reservation Waste Management Plan

    SciTech Connect

    Turner, J.W.

    1995-02-01

    This report presents the waste management plan for the Oak Ridge Reservation facilities. The primary purpose is to convey what facilities are being used to manage wastes, what forces are acting to change current waste management systems, and what plans are in store for the coming fiscal year.

  20. Remedial Investigation Work Plan for Chestnut Ridge Operable Unit 1 (Chestnut Ridge Security Pits) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1993-09-01

    This Remedial Investigation (RI) Work Plan specifically addresses Chestnut Ridge Operable Unit 1, (OU1) which consists of the Chestnut Ridge Security Pits (CRSP). The CRSP are located {approximately}800 ft southeast of the central portion of the Y-12 Plant atop Chestnut Ridge, which is bounded to the northwest by Bear Creek Valley and to the southeast by Bethel Valley. Operated from 1973 to 1988, the CRSP consisted of a series of trenches used for the disposal of classified hazardous and nonhazardous waste materials. Disposal of hazardous waste materials was discontinued in December 1984, while nonhazardous waste disposal ended on November 8, 1988. An RI is being conducted at this site in response to CERCLA regulations. The overall objectives of the RI are to collect data necessary to evaluate the nature and extent of contaminants of concern (COC), support an ecological risk assessment (ERA) and a human health risk assessment (HHRA), support the evaluation of remedial alternatives, and ultimately develop a Record of Decision for the site. The purpose of this Work Plan is to outline RI activities necessary to define the nature and extent of suspected contaminants at Chestnut Ridge OU1. Potential migration pathways also will be investigated. Data collected during the RI will be used to evaluate the overall risk posed to human health and the environment by OU1.

  1. Ridged Terrain on the Floor Melas Chasma

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Are these dunes? One of the most puzzling findings of the Mars Global Surveyor Mars Orbiter Camera investigation has been the discovery of many surfaces of sharp, parallel ridges and grooves that--at first glance--look like dunes, but upon closer inspection turn out to be something else. They aren't dunes because they occur too close together, their crests are too sharp, and their slopes are too symmetrical. In most places that they occur on Mars, they appear to be occurring within a specific layer of (usually) dark material. Exactly what processes make these ridges is a mystery, but it clearly involves some sort of erosion. Dark mesas in this picture of the floor of Melas Chasma in the Valles Marineris system are developing sharp, parallel troughs and pits that appear to eventually erode to become the fields of ridges seen throughout the rest of the image. Dark, ridged surfaces like this are common in the central floors of Valles Marineris and elsewhere in the equatorial regions of Mars, and present a type of surface that may need to be avoided by future Mars landers. This image, illuminated by sunlight from the left, covers an area 3 kilometers (1.9 miles) wide and 14.5 kilometers (9 miles) long. The scene is located near 8.8oS, 76.8oW and was acquired on March 22, 1999.

  2. Blue Ridge Technical College Adult Reading Project.

    ERIC Educational Resources Information Center

    Kessler, Caren

    The development and implementation of a tutor training program designed to eliminate adult illiteracy in one area of North Carolina are described in this paper. Various sections of the paper provide information about (1) the history of the program, which was initiated by staff members at the learning center of the Blue Ridge Technical College in…

  3. ABCDEFG IS - the principle of constructive feedback.

    PubMed

    Bhattarai, M

    2007-01-01

    Feedback is an integral part of any learning experience. Constructive feedback is a powerful instrument and facilitates the learner's professional and personal development. "ABCDEFG IS", a mnemonic for the principles of constructive feedback, stands for Amount of the information, Benefit of the trainees, Change behaviour, Descriptive language, Environment, Focused, Group check, Interpretation check, and Sharing information. The eight important steps of feedback are: Ensure prior information, Collect data, Make appropriate meeting arrangement, Begin by encouraging self assessment by the trainee, Highlight areas where the trainee is doing well, Give feedback, Handle reaction maintaining the dignity and Plan actions. Communication and reflection also share many of the principles and steps of constructive feedback and giving regular feedback, thus, helps to improve communication and reflection. The feedback provider would be able to provide genuine feedback by following the appropriate steps and principles of constructive feedback and realize how important and rewarding its role is in teaching learning activities. PMID:18274573

  4. Lomonosov Ridge off Greenland (LOMROG) 2007

    NASA Astrophysics Data System (ADS)

    Marcussen, C.; Jakobsson, M.

    2007-12-01

    The Lomonosov Ridge off Greenland was the primary focus for the LOMROG expedition. This part of the Arctic is virtually unexplored as difficult sea ice conditions have made it inaccessible for surface vessels. With Swedish icebreaker /Oden/ supported by new Russian nuclear icebreaker /50 Let Pobedy/, LOMROG managed to reach the southern most tip of the Lomonosov Ridge off Greenland to carry out multibeam mapping, subbottom and seismic reflection profiling, gravity measurements, geological coring and oceanographic station work. The LOMROG expedition is a Swedish/Danish collaboration project with participating scientists also from Canada, Finland, and USA. The data collection was made for the purpose of studying paleoceanography/oceanography, glacial history and the tectonic evolution of the of the Arctic Ocean as well as for Denmark's Continental Shelf Project under the United Nations Convention on the Law of the Sea Article 76. One of the reasons for targeting the ice-infested area north of Greenland was that it likely holds answers to key questions regarding the glacial history of the Arctic Ocean, such as whether immense ice shelves existed in the Arctic Ocean during past glacial periods./ /Previous expeditions with /Oden/ in 1996 and the US nuclear submarine /Hawkbill/ in 1999, have demonstrated the occurrence of ice grounding down to 1000 m present water depth at about 87°N 145°E on the Lomonosov Ridge crest. If this ice grounding event resulted from a much debated, but supposedly coherent and large floating ice shelf, the Lomonosov Ridge north of Greenland must also be scoured. To test the hypothesis of a huge Arctic Ocean ice shelf LOMROG mapped the areas of the Lomonosov Ridge north of Greenland using the new EM120 multibeam bathymetry and SBP120 subbottom profiling system installed on the /Oden/ during the spring of 2007. Glacial erosion was indeed found at water depth shallower than approximately 800 m and two sediment cores retrieved from the glacially

  5. Supernova Feedback in Galaxy Formation

    NASA Astrophysics Data System (ADS)

    Dubois, Y.; Teyssier, R.

    2008-06-01

    The hierarchical model of galaxy formation is known to suffer from the ``over-cooling'' problem: the high efficiency of radiative cooling results in too much baryonic matter in a condensed phase (namely, cold gas or stars) when compared to observations. A solution proposed by many authors (see Springel & Hernquist 2003; Fujita et al. 2004; Rasera & Teyssier 2005) is feedback due to supernova (SN) driven winds or active galactic nuclei. Modeling SN feedback by direct injection of thermal energy usually turns out to be inefficient in galaxy-scale simulations, due to the quasi-instantaneous radiation of the SN energy. To avoid this effect, we have developed a new method to incorporate SN feedback in cosmological simulations: using temporary test particles, we reproduce explicitly a local Sedov blast wave solution in the gas distribution. We have performed several self-consistent runs of isolated Navarro, Frenk, & White (1996, hereafter NFW) halos with radiative cooling, star formation, SN feedback and metal enrichment using the adaptive mesh refinement code RAMSES (Teyssier 2002). We have explored the influence of SN feedback on the formation and the evolution of galaxies with different masses. We have studied the efficiency of the resulting galactic winds, as a function of the mass of the parent halo.

  6. Louisiana slope salt-ridge continuity confirmed

    SciTech Connect

    Lowrie, A.; Hoffman, K.S.; Sullivan, N.

    1989-03-01

    The Louisiana offshore is a world-class hydrocarbon province. Abundant reservoirs develop as the result of interaction between salt tectonics and sedimentation. Thus, it is essential to know both regional and local characteristics of the extent and timing of salt tectonics as an aid in hydrocarbon exploration. Exploration mythology mandates that salt domes and ridges are virtually random across the slope area. In sharp contrast, the authors describe a definite pattern to the salt ridges of slightly concave (to the north) arcs, with the southernmost arc located along the Sigsbee Escarpment and the northernmost along the shelf break. Furthermore, salt domes may not be truly randomly located but rather part of ancestral or existent salt ridges. Confirming data are provided by dip bathymatric and seismic profiles. The bathymetric profiles are at 5-mi (8-km) spacings from 1987 published charts of the Gulf of Mexico. Dip seismic lines reveal that bathymetric highs are associated with underlying salt. Buried salt accumulations are surficially expressed by actual ridges and domes, a leveling of sea floor, or a local decrease in the rate of regional slope descent. Salt is the Neogene-age basement of the Louisiana slope. The existence of an overall salt-ridge pattern implies that there is a single dynamic geologic system controlling the evolution of this slope. As salt tectonic rates and timing are deciphered for specific sites along dip, intervening rates may be interpolated to unmapped zones. Confirming an overall salt tectonic pattern is mandatory prior to quantifying regional and specific rates for the whole slope.

  7. An interdisciplinary management of severely resorbed maxillary anterior ridge complicated by traumatic bite using a ridge splitting technique

    PubMed Central

    Gupta, Narender Dev; Maheshwari, Sandhya; Chaudhari, Prabhat Kumar; Rathi, Shraddha

    2015-01-01

    Injury to the teeth and alveolar ridge of the maxillary anterior region due to trauma can cause severe alveolar ridge deficiency. Ridge augmentation is a valuable periodontal plastic surgical method for the correction of ridge defects for esthetic purpose. Although ridge augmentation can help to restore the ridge volume, the grafting procedures can significantly increase the patient morbidity, treatment time, and the cost. Among the ridge augmentation techniques, the ridge split procedure demonstrates many benefits such as no need for donor site, the rare risk of damage to underlying anatomical structures, less pain, and swelling. This case report presents a vertical split technique for increasing the bone volume. There was a remarkable healing and significant increase in bone volume. We have followed the case for 6 months. PMID:25810602

  8. Parallel multiplex laser feedback interferometry

    SciTech Connect

    Zhang, Song; Tan, Yidong; Zhang, Shulian

    2013-12-15

    We present a parallel multiplex laser feedback interferometer based on spatial multiplexing which avoids the signal crosstalk in the former feedback interferometer. The interferometer outputs two close parallel laser beams, whose frequencies are shifted by two acousto-optic modulators by 2Ω simultaneously. A static reference mirror is inserted into one of the optical paths as the reference optical path. The other beam impinges on the target as the measurement optical path. Phase variations of the two feedback laser beams are simultaneously measured through heterodyne demodulation with two different detectors. Their subtraction accurately reflects the target displacement. Under typical room conditions, experimental results show a resolution of 1.6 nm and accuracy of 7.8 nm within the range of 100 μm.

  9. A stratospheric water vapor feedback

    NASA Astrophysics Data System (ADS)

    Dessler, A. E.; Schoeberl, M. R.; Wang, T.; Davis, S. M.; Rosenlof, K. H.

    2013-12-01

    Variations in stratospheric water vapor play a role in the evolution of our climate. We show here that variations in water vapor since 2004 can be traced to tropical tropopause layer (TTL) temperature perturbations from at least three processes: the quasi-biennial oscillation, the strength of the Brewer-Dobson circulation, and the temperature of the troposphere. The connection between stratospheric water vapor and the temperature of the troposphere implies the existence of a stratospheric water vapor feedback. We estimate the feedback in a chemistry-climate model to have a magnitude of +0.3 W/m2/K, which could be a significant contributor to the overall climate sensitivity. About two-thirds of the feedback comes from the extratropical stratosphere below ~16 km (the lowermost stratosphere), with the rest coming from the stratosphere above ~16 km (the overworld).

  10. Optical fiber feedback SQUID magnetometer

    SciTech Connect

    Naito, S.; Sampei, Y.; Takahashi, T. )

    1989-04-01

    This paper describes an optical fiber feedback superconducting quantum interference device (SQUID) magnetometer which was developed to improve electromagnetic interference characteristics. The SQUID consists of an RF SQUID probe, an RF amplifier, two multimode fibers, and a SQUID control unit. Phase-locked pulse width modulation (PWM) was used to construct a flux locked loop (FLL) circuit in the SQUID control unit. The operation of the optical fiber feedback SQUID is stable when a common mode voltage of ac 100 V/50 Hz is applied. It has an energy resolution of 1 x 10/sup -28/ J/Hz. This paper also describes the measurement of an auditory evoked field from the human brain in a magnetically shielded room using the fiber feedback SQUID with a gradiometer type pickup coil.

  11. Force feedback in limb lengthening.

    PubMed

    Wee, Jinyong; Rahman, Tariq; Seliktar, Rahamim; Akins, Robert; Levine, David; Richardson, Dean; Dodge, George R; Thabet, Ahmed M; Holmes, Lauren; Mackenzie, William G

    2010-01-01

    A new variable-rate distraction system using a motorized distractor driven by feedback from the distraction force was designed. The distractor was mounted on a unilateral fixator and attached to the tibiae of 6 sheep that underwent distraction osteogenesis. The sheep were divided equally into 3 groups. In group 1, the forces were recorded but were not used to drive the lengthening rate. In group 2, force feedback was used and the desired distraction force level was set to 300 N and the initial rate was 1 mm/day. Group 3 also underwent force feedback with the desired force limit at 300 N, but the rate change was initiated earlier, at 200 N. The distraction force was recorded at 15 second intervals throughout the distraction phase and stored onboard the distractor.

  12. Mid-ocean ridge jumps associated with hotspot magmatism

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, Eric; Ito, Garrett; Behn, Mark D.

    2008-02-01

    Hotspot-ridge interaction produces a wide range of phenomena including excess crustal thickness, geochemical anomalies, off-axis volcanic ridges and ridge relocations or jumps. Ridges are recorded to have jumped toward many hotspots including, Iceland, Discovery, Galápagos, Kerguelen and Tristan de Cuhna. The causes of ridge jumps likely involve a number of interacting processes related to hotspots. One such process is reheating of the lithosphere as magma penetrates it to feed near-axis volcanism. We study this effect by using the hybrid, finite-element code, FLAC, to simulate two-dimensional (2-D, cross-section) viscous mantle flow, elasto-plastic deformation of the lithosphere and heat transport in a ridge setting near an off-axis hotspot. Heating due to magma transport through the lithosphere is implemented within a hotspot region of fixed width. To determine the conditions necessary to initiate a ridge jump, we vary four parameters: hotspot magmatic heating rate, spreading rate, seafloor age at the location of the hotspot and ridge migration rate. Our results indicate that the hotspot magmatic heating rate required to initiate a ridge jump increases non-linearly with increasing spreading rate and seafloor age. Models predict that magmatic heating, itself, is most likely to cause jumps at slow spreading rates such as at the Mid-Atlantic Ridge on Iceland. In contrast, despite the higher magma flux at the Galápagos hotspot, magmatic heating alone is probably insufficient to induce a ridge jump at the present-day due to the intermediate ridge spreading rate of the Galápagos Spreading Center. The time required to achieve a ridge jump, for fixed or migrating ridges, is found to be on the order of 10 5-10 6 years. Simulations that incorporate ridge migration predict that after a ridge jump occurs the hotspot and ridge migrate together for time periods that increase with magma flux. Model results also suggest a mechanism for ridge reorganizations not related to

  13. ASDTIC - A feedback control innovation.

    NASA Technical Reports Server (NTRS)

    Lalli, V. R.; Schoenfeld, A. D.

    1972-01-01

    The ASDTIC (analog signal to discrete time interval converter) control subsystem provides precise output control of high performance aerospace power supplies. The key to ASDTIC operation is that it stably controls output by sensing output energy change as well as output magnitude. The ASDTIC control subsystem and control module were developed to improve power supply performance during static and dynamic input voltage and output load variations, to reduce output voltage or current regulation due to component variations or aging, to maintain a stable feedback control with variations in the loop gain or loop time constants, and to standardize the feedback control subsystem for power conditioning equipment.

  14. ASDTIC: A feedback control innovation

    NASA Technical Reports Server (NTRS)

    Lalli, V. R.; Schoenfeld, A. D.

    1972-01-01

    The ASDTIC (Analog Signal to Discrete Time Interval Converter) control subsystem provides precise output control of high performance aerospace power supplies. The key to ASDTIC operation is that it stably controls output by sensing output energy change as well as output magnitude. The ASDTIC control subsystem and control module were developed to improve power supply performance during static and dynamic input voltage and output load variations, to reduce output voltage or current regulation due to component variations or aging, to maintain a stable feedback control with variations in the loop gain or loop time constants, and to standardize the feedback control subsystem for power conditioning equipment.

  15. Weekly Feedback vs. Daily Feedback: An Application in Retail

    ERIC Educational Resources Information Center

    MacDonald, Jennifer E.; Mullin, Jill; Wilder, David A.

    2004-01-01

    Two experiments were conducted in a retail setting to (a) assess the effectiveness of a multi-component performance management intervention and (b) compare the effectiveness of weekly and daily feedback. During the first experiment, a multiple baseline design was used to evaluate the effectiveness of task clarification, goal setting, access to…

  16. Initiation of Ridges and Transform Faults

    NASA Astrophysics Data System (ADS)

    Nyst, M.; Thompson, G. A.; Parsons, T.

    2004-12-01

    No clear consensus has emerged to explain initiation of the strikingly regular pattern of ocean ridges and transform faults. The question is important on the continents also, because a less regular pattern of step-overs on faults such as the San Andreas influences the sources of earthquakes. We explore the question by finite element modeling and a study of observational data on ridges and transforms. We focus on the simplest case, where ridges and transforms seem to self-organize at new plate boundaries as soon as new oceanic (magmatic) crust forms. The South Atlantic supplies a clear example. Continental South America and Africa separated along an irregular break, whose general shape is still preserved in the Mid-Atlantic Ridge. In detail, however, the sea floor magnetic anomalies and satellite gravity show that traces of the ridges and transforms extend to the base of the continental slope, i.e. they formed quickly in the new oceanic crust. The Gulf of California provides another clear example and is notable because of its northward transition into the continental San Andreas fault system. In continental crust, dike segments connected by transform faults provide the clearest analogues of oceanic ridges and transforms. Remarkably, the ridge-transform pattern has been simulated by pulling the crust on molten wax [Oldenburg and Brune, JGR, 80, 1975] and also observed in the crust of a molten lava lake [Duffield, JGR, 77, 1972]. In neither of these models, however, do the spatial and temporal scales permit investigation of the dikes whose repeated emplacement and inflation builds layer 3 of the ocean crust. It is well established that, under a buoyant head of magma, dikes tend to fracture and intrude the crust in planes perpendicular to the least horizontal stress, and they relieve the stress difference as they inflate [e.g. Parsons and Thompson, Science, 253, 1991]. Dikes are commonly used as stress-direction indicators analogous to artificial hydraulic fractures

  17. 78 FR 2431 - Notice of Inventory Completion: U.S. Department of Energy Oak Ridge Office, Oak Ridge, TN...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-11

    .... Department of Energy Oak Ridge Office has corrected an inventory of human remains and associated funerary... of Energy Oak Ridge Office. Repatriation of the human remains and associated funerary object to the... object in the possession of the U.S. Department of Energy Oak Ridge Office. The human remains...

  18. Feedback mechanisms linking barrier island transgression and storm response with beach-dune interaction

    NASA Astrophysics Data System (ADS)

    Houser, C.

    2010-12-01

    This paper examines the multi-scale feedback relationship of event-scale sediment exchange between beach and dune with long-term barrier island transgression. Using field and remotely sensed data from Santa Rosa Island in northwest Florida and South Padre Island in Texas, it is shown how the alongshore variation in storm washover and breaching is coherent (but in different ways) with transverse ridges that developed on the inner-shelf as the island transgressed. Model results suggest that the ridges are reinforced during tropical storms and hurricanes through the offshore transport of beach and dune sediment eroded by the storm surge. These ridges force an alongshore variation in beach and nearshore state that determines the aeolian transport potential and available sediment supplied from beach to dune. On Santa Rosa Island, dune aeolian transport and dune heights are limited by the steep beachface, such that the largest dunes are found at the crest of the transverse ridges where the beachface is more intermediate. In contrast, Aeolian transport and dune heights are shown to be supply limited on Padre Island, which has a relatively dissipative nearshore and beach. The largest dunes on Padre Island are found between transverse ridges where the profile is more intermediate and sediment is more readily supplied by inter- and supra-tidal swash bars. As a consequence, the largest storm surge and washover occurs at the transverse ridges where the dunes are small, while on Santa Rosa Island, the storm surge is greater where the dunes are larger leading to greater loss of sediment offshore. While Padre Island and Santa Rosa Island represent different beach states and exhibit different mechanisms of beach-dune interaction and storm impact, it is shown that small-scale beach-dune interaction is as much dependent on the geologic framework of the island, which developed as it transgressed, as the transgression and storm response are dependent on the exchange of sediment

  19. Divergent Ridge Features on the Juan de Fuca and Gorda Ridges

    NASA Astrophysics Data System (ADS)

    Eaton, M. E.; Sautter, L.; Steele, M.

    2014-12-01

    Multibeam data collected using a Kongsberg EM122 sonar system on the NOAA ship R/V Marcus G. Langseth led by chief scientist Douglas Toomey (University of Oregon) in 2009 and with a Simrad EM302 sonar system on two NOAA ship Okeanos Explorer cruises led by chief scientists James Gardner (University of New Hampshire) and Catalina Martinez (University of Rhode Island) in 2009 show the morphology of the Juan de Fuca and Gorda Ridges, as well as the Blanco and Mendocino Fracture Zones. These ridges and fracture zones comprise the divergent plate boundary of the eastern edge of the Pacific Plate and the western edges of the Juan de Fuca and Gorda Plates. Both plates are being subducted beneath the western edge of the North American Plate. CARIS HIPS 8.1 software was used to process the multibeam data and create bathymetric images. The ridge axes, located off the coast of Washington and Oregon (USA) adjacent to the Cascadia Basin, indicate obvious signs of spreading, due to the series of faults and rocky ridges aligned parallel to the plate boundaries. Fault and ridge orientations are used to compare the direction of seafloor spreading, and indicate that both the Juan de Fuca Plate and Gorda Plate are spreading in a southeastern direction. Younger ridges from the Gorda Ridge system mapped in the study run parallel to the boundary, however older ridges do not show the same orientation, indicating a change in spreading direction. The presence of hydrothermal vents along the Juan de Fuca Ridge is also evidence of the active boundary, as the vent chimneys are composed of minerals and metals precipitated from the hot water heated by magma from beneath the spreading seafloor. In this study, the data are used to compare and contrast earthquake seismicity and ridge morphologies at a depth range of approximately 762 to 2134 meters. The diverging Pacific, Juan de Fuca, and Gorda Plates along with the San Andreas Fault have potential to increase seismic and volcanic activity around

  20. Neural correlates of feedback processing in toddlers.

    PubMed

    Meyer, Marlene; Bekkering, Harold; Janssen, Denise J C; de Bruijn, Ellen R A; Hunnius, Sabine

    2014-07-01

    External feedback provides essential information for successful learning. Feedback is especially important for learning in early childhood, as toddlers strongly rely on external signals to determine the consequences of their actions. In adults, many electrophysiological studies have elucidated feedback processes using a neural marker called the feedback-related negativity (FRN). The neural generator of the FRN is assumed to be the ACC, located in medial frontal cortex. As frontal brain regions are the latest to mature during brain development, it is unclear when in early childhood a functional feedback system develops. Is feedback differentiated on a neural level in toddlers and in how far is neural feedback processing related to children's behavioral adjustment? In an EEG experiment, we addressed these questions by measuring the brain activity and behavioral performance of 2.5-year-old toddlers while they played a feedback-guided game on a touchscreen. Electrophysiological results show differential brain activity for feedback with a more negative deflection for incorrect than correct outcomes, resembling the adult FRN. This provides the first neural evidence for feedback processing in toddlers. Notably, FRN amplitudes were predictive of adaptive behavior: the stronger the differential brain activity for feedback, the better the toddlers' adaptive performance during the game. Thus, already in early childhood toddlers' feedback-guided performance directly relates to the functionality of their neural feedback processing. Implications for early feedback-based learning as well as structural and functional brain development are discussed.

  1. Growth of a tectonic ridge during the Landers earthquake

    SciTech Connect

    Fleming, R.W.; Johnson, A.M.

    1997-04-01

    The formation of tectonic ridges by localized vertical uplift along strike-slip faults has long been suspected, but the actual growth of a tectonic ridge during an earthquake has never been documented. During the 1992 Landers, California, earthquake sequence, an awl-shaped, dome-like topographic ridge along the Emerson fault zone increased its height at least 1 m concurrently with 3 m of right-lateral shift across the fault zone containing the ridge. Five deformation vectors within the ridge reveal dilatant behavior in addition to the uplift and shift on boundary faults. 10 refs., 5 figs.

  2. Large-scale deformation associated with ridge subduction

    USGS Publications Warehouse

    Geist, E.L.; Fisher, M.A.; Scholl, D. W.

    1993-01-01

    Continuum models are used to investigate the large-scale deformation associated with the subduction of aseismic ridges. Formulated in the horizontal plane using thin viscous sheet theory, these models measure the horizontal transmission of stress through the arc lithosphere accompanying ridge subduction. Modelling was used to compare the Tonga arc and Louisville ridge collision with the New Hebrides arc and d'Entrecasteaux ridge collision, which have disparate arc-ridge intersection speeds but otherwise similar characteristics. Models of both systems indicate that diffuse deformation (low values of the effective stress-strain exponent n) are required to explain the observed deformation. -from Authors

  3. Growth of a tectonic ridge during the Landers earthquake

    USGS Publications Warehouse

    Fleming, R.W.; Johnson, A.M.

    1997-01-01

    The formation of tectonic ridges by localized vertical uplift along strike-slip faults has long been suspected, but the actual growth of a tectonic ridge during an earthquake has never been documented. During the 1992 Landers, California, earthquake sequence, an awl-shaped, dome-like topographic ridge along the Emerson fault zone increased its height at least 1 m concurrently with 3 m of right-lateral shift across the fault zone containing the ridge. Five deformation vectors within the ridge reveal dilatant behavior in addition to the uplift and shift on boundary faults.

  4. An ultraslow-spreading class of ocean ridge.

    PubMed

    Dick, Henry J B; Lin, Jian; Schouten, Hans

    2003-11-27

    New investigations of the Southwest Indian and Arctic ridges reveal an ultraslow-spreading class of ocean ridge that is characterized by intermittent volcanism and a lack of transform faults. We find that the mantle beneath such ridges is emplaced continuously to the seafloor over large regions. The differences between ultraslow- and slow-spreading ridges are as great as those between slow- and fast-spreading ridges. The ultraslow-spreading ridges usually form at full spreading rates less than about 12 mm yr(-1), though their characteristics are commonly found at rates up to approximately 20 mm yr(-1). The ultraslow-spreading ridges consist of linked magmatic and amagmatic accretionary ridge segments. The amagmatic segments are a previously unrecognized class of accretionary plate boundary structure and can assume any orientation, with angles relative to the spreading direction ranging from orthogonal to acute. These amagmatic segments sometimes coexist with magmatic ridge segments for millions of years to form stable plate boundaries, or may displace or be displaced by transforms and magmatic ridge segments as spreading rate, mantle thermal structure and ridge geometry change.

  5. An ultraslow-spreading class of ocean ridge.

    PubMed

    Dick, Henry J B; Lin, Jian; Schouten, Hans

    2003-11-27

    New investigations of the Southwest Indian and Arctic ridges reveal an ultraslow-spreading class of ocean ridge that is characterized by intermittent volcanism and a lack of transform faults. We find that the mantle beneath such ridges is emplaced continuously to the seafloor over large regions. The differences between ultraslow- and slow-spreading ridges are as great as those between slow- and fast-spreading ridges. The ultraslow-spreading ridges usually form at full spreading rates less than about 12 mm yr(-1), though their characteristics are commonly found at rates up to approximately 20 mm yr(-1). The ultraslow-spreading ridges consist of linked magmatic and amagmatic accretionary ridge segments. The amagmatic segments are a previously unrecognized class of accretionary plate boundary structure and can assume any orientation, with angles relative to the spreading direction ranging from orthogonal to acute. These amagmatic segments sometimes coexist with magmatic ridge segments for millions of years to form stable plate boundaries, or may displace or be displaced by transforms and magmatic ridge segments as spreading rate, mantle thermal structure and ridge geometry change. PMID:14647373

  6. The Secret of Effective Feedback

    ERIC Educational Resources Information Center

    Wiliam, Dylan

    2016-01-01

    "The only important thing about feedback is what students do with it," declares Dylan Wiliam in this article. The standard school procedure (in which a teacher looks at a piece of student work and writes something on it, and the student later looks at what the teacher has written) does not necessarily increase student learning. Teachers…

  7. Feedback: How to Teach How.

    ERIC Educational Resources Information Center

    Krovar, Susan K.; And Others

    1992-01-01

    To give definitive feedback, physical education teachers must be able to teach basic kinesiological and mechanical principles of movement and how they apply to specific sports skills. The article includes a chart with common kinesiological and mechanical principles applied to particular movements. Appropriate teaching cues are noted. (SM)

  8. Educational Accountability and Policy Feedback

    ERIC Educational Resources Information Center

    McDonnell, Lorraine M.

    2013-01-01

    Over the past 30 years, accountability policies have become more prominent in public K-12 education and have changed how teaching and learning are organized. It is less clear the extent to which these policies have altered the politics of education. This article begins to address that question through the lens of policy feedback. It identifies…

  9. Delayed Auditory Feedback and Movement

    ERIC Educational Resources Information Center

    Pfordresher, Peter Q.; Dalla Bella, Simone

    2011-01-01

    It is well known that timing of rhythm production is disrupted by delayed auditory feedback (DAF), and that disruption varies with delay length. We tested the hypothesis that disruption depends on the state of the movement trajectory at the onset of DAF. Participants tapped isochronous rhythms at a rate specified by a metronome while hearing DAF…

  10. LFSC - Linac Feedback Simulation Code

    SciTech Connect

    Ivanov, Valentin; /Fermilab

    2008-05-01

    The computer program LFSC (Feedback Simulation Code>) is a numerical tool for simulation beam based feedback in high performance linacs. The code LFSC is based on the earlier version developed by a collective of authors at SLAC (L.Hendrickson, R. McEwen, T. Himel, H. Shoaee, S. Shah, P. Emma, P. Schultz) during 1990-2005. That code was successively used in simulation of SLC, TESLA, CLIC and NLC projects. It can simulate as pulse-to-pulse feedback on timescale corresponding to 5-100 Hz, as slower feedbacks, operating in the 0.1-1 Hz range in the Main Linac and Beam Delivery System. The code LFSC is running under Matlab for MS Windows operating system. It contains about 30,000 lines of source code in more than 260 subroutines. The code uses the LIAR ('Linear Accelerator Research code') for particle tracking under ground motion and technical noise perturbations. It uses the Guinea Pig code to simulate the luminosity performance. A set of input files includes the lattice description (XSIF format), and plane text files with numerical parameters, wake fields, ground motion data etc. The Matlab environment provides a flexible system for graphical output.

  11. Feedback sandwiches affect perceptions but not performance.

    PubMed

    Parkes, Jay; Abercrombie, Sara; McCarty, Teresita

    2013-08-01

    The feedback sandwich technique-make positive comments; provide critique; end with positive comments-is commonly recommended to feedback givers despite scant evidence of its efficacy. These two studies (N = 20; N = 350) of written peer feedback with third-year medical students on clinical patient note-writing assignments indicate that students think feedback sandwiches positively impact subsequent performance when there is no evidence that they do. The effort necessary to produce feedback sandwiches and students' unwarranted confidence in their performance impact have implications for teaching about how to give feedback.

  12. Gender differentiation by finger ridge count among South Indian population.

    PubMed

    Nithin, M D; Manjunatha, B; Preethi, D S; Balaraj, B M

    2011-02-01

    The goal of this study is to determine the gender based on finger ridge count within a well-defined area. Rolled fingerprints were taken from 550 subjects (275 men and 275 women) belonging to South Indian population all within the age range of 18-65 years. Results show that women have a significantly higher ridge count than men. Application of Baye's theorem suggests that a fingerprint possessing ridge density <13 ridges/25 mm(2) is most likely to be of male origin. Likewise, a fingerprint having ridge count >14 ridges/25 mm(2) are most likely to be of female origin. These results are helpful as a tool for fingerprint experts as they can be used as a presumptive indicator of gender based on the degree of ridge density. PMID:21315302

  13. Faulting and folding in the formation of planetary wrinkle ridges

    NASA Astrophysics Data System (ADS)

    Golombek, M. P.; Plescia, J. B.; Franklin, B. J.

    Topographic profiles for planetary wrinkle ridges compiled from high-resolution Lunar Topographic Orthophoto maps for the moon and from monoscopic photoclinometry data for Mars reveal that many of these ridges are characterized by an elevation offset between one side of a ridge and the other. To investigate the relative importance of faulting and folding in the formation of planetary wrinkle ridges, this paper develops a model of subsurface structure, based on observations and measurements of surface physiography and topography by Golombek and Franklin (1987) and Plescia (1990), and assumptions of subsurface structure, which makes it possible to estimate shortening across wrinkle ridges on Moon and Mars. According to this model, total ridge shortening is on the order of 100 m; shortening due to faulting exceeds shortening due to folding for fault dips up to 60-80 deg, implying that faults beneath many wrinkle ridges break the surface to accomodate the greater displacement along the fault than is accomodated in the fold.

  14. Dielectric ridge waveguide gas laser apparatus

    SciTech Connect

    DeMaria, A.J.; Bridges, W.

    1989-03-14

    A dielectric ridged waveguide flowing gas laser apparatus is described, comprising in combination; a dielectric substrate having a predetermined number of the grooves formed theron, the grooves extending along the longitudinal axis of the dielectric substrate, an electrically conductive member in parallel alignment with the grooved side of the dielectric substrate such that an air gasp is formed therebetween the air gap containing an active laser gas medium, electrically conductive strips disposed on the outside of the dielectric substrate forming electrodes, the conductive strips being aligned with the grooves and having the same length and width as the grooves, and an excitation source connected between the conductive member and the conductive strips, to provide lasing in the ridged waveguide.

  15. Laterally Coupled Quantum-Dot Distributed-Feedback Lasers

    NASA Technical Reports Server (NTRS)

    Qui, Yueming; Gogna, Pawan; Muller, Richard; Maker, paul; Wilson, Daniel; Stintz, Andreas; Lester, Luke

    2003-01-01

    InAs quantum-dot lasers that feature distributed feedback and lateral evanescent- wave coupling have been demonstrated in operation at a wavelength of 1.3 m. These lasers are prototypes of optical-communication oscillators that are required to be capable of stable single-frequency, single-spatial-mode operation. A laser of this type (see figure) includes an active layer that comprises multiple stacks of InAs quantum dots embedded within InGaAs quantum wells. Distributed feedback is provided by gratings formed on both sides of a ridge by electron lithography and reactive-ion etching on the surfaces of an AlGaAs/GaAs waveguide. The lateral evanescent-wave coupling between the gratings and the wave propagating in the waveguide is strong enough to ensure operation at a single frequency, and the waveguide is thick enough to sustain a stable single spatial mode. In tests, the lasers were found to emit continuous-wave radiation at temperatures up to about 90 C. Side modes were found to be suppressed by more than 30 dB.

  16. Oak Ridge National Laboratory Waste Management Plan

    SciTech Connect

    Not Available

    1992-12-01

    The objective of the Oak Ridge National Laboratory Waste Management Plan is to compile and to consolidate information annually on how the ORNL Waste Management Program is conducted, which waste management facilities are being used to manage wastes, what forces are acting to change current waste management systems, what activities are planned for the forthcoming fiscal year (FY), and how all of the activities are documented.

  17. Fingerprint image mosaicking by recursive ridge mapping.

    PubMed

    Choi, Kyoungtaek; Choi, Heeseung; Lee, Sangyoun; Kim, Jaihie

    2007-10-01

    To obtain a large fingerprint image from several small partial images, mosaicking of fingerprint images has been recently researched. However, existing approaches cannot provide accurate transformations for mosaics when it comes to aligning images because of the plastic distortion that may occur due to the nonuniform contact between a finger and a sensor or the deficiency of the correspondences in the images. In this paper, we propose a new scheme for mosaicking fingerprint images, which iteratively matches ridges to overcome the deficiency of the correspondences and compensates for the amount of plastic distortion between two partial images by using a thin-plate spline model. The proposed method also effectively eliminates erroneous correspondences and decides how well the transformation is estimated by calculating the registration error with a normalized distance map. The proposed method consists of three phases: feature extraction, transform estimation, and mosaicking. Transform is initially estimated with matched minutia and the ridges attached to them. Unpaired ridges in the overlapping area between two images are iteratively matched by minimizing the registration error, which consists of the ridge matching error and the inverse consistency error. During the estimation, erroneous correspondences are eliminated by considering the geometric relationship between the correspondences and checking if the registration error is minimized or not. In our experiments, the proposed method was compared with three existing methods in terms of registration accuracy, image quality, minutia extraction rate, processing time, reject to fuse rate, and verification performance. The average registration error of the proposed method was less than three pixels, and the maximum error was not more than seven pixels. In a verification test, the equal error rate was reduced from 10% to 2.7% when five images were combined by our proposed method. The proposed method was superior to other

  18. ORNL (Oak Ridge National Laboratory) 89

    SciTech Connect

    Anderson, T.D.; Appleton, B.R.; Jefferson, J.W.; Merriman, J.R.; Mynatt, F.R.; Richmond, C.R.; Rosenthal, M.W.

    1989-01-01

    This is the inaugural issues of an annual publication about the Oak Ridge National Laboratory. Here you will find a brief overview of ORNL, a sampling of our recent research achievements, and a glimpse of the directions we want to take over the next 15 years. A major purpose of ornl 89 is to provide the staff with a sketch of the character and dynamics of the Laboratory.

  19. The mean composition of ocean ridge basalts

    NASA Astrophysics Data System (ADS)

    Gale, Allison; Dalton, Colleen A.; Langmuir, Charles H.; Su, Yongjun; Schilling, Jean-Guy

    2013-03-01

    mean composition of mid-ocean ridge basalts (MORB) is determined using a global data set of major elements, trace elements, and isotopes compiled from new and previously published data. A global catalog of 771 ridge segments, including their mean depth, length, and spreading rate enables calculation of average compositions for each segment. Segment averages allow weighting by segment length and spreading rate and reduce the bias introduced by uneven sampling. A bootstrapping statistical technique provides rigorous error estimates. Based on the characteristics of the data, we suggest a revised nomenclature for MORB. "ALL MORB" is the total composition of the crust apart from back-arc basins, N-MORB the most likely basalt composition encountered along the ridge >500 km from hot spots, and D-MORB the depleted end-member. ALL MORB and N-MORB are substantially more enriched than early estimates of normal ridge basalts. The mean composition of back-arc spreading centers requires higher extents of melting and greater concentrations of fluid-mobile elements, reflecting the influence of water on back-arc petrogenesis. The average data permit a re-evaluation of several problems of global geochemistry. The K/U ratio reported here (12,340 ± 840) is in accord with previous estimates, much lower than the estimate of Arevalo et al. (2009). The low Sm/Nd and 143Nd/144Nd ratio of ALL MORB and N-MORB provide constraints on the hypothesis that Earth has a non-chondritic primitive mantle. Either Earth is chondritic in Sm/Nd and the hypothesis is incorrect or MORB preferentially sample an enriched reservoir, requiring a large depleted reservoir in the deep mantle.

  20. Global desertification: Drivers and feedbacks

    NASA Astrophysics Data System (ADS)

    D'Odorico, Paolo; Bhattachan, Abinash; Davis, Kyle F.; Ravi, Sujith; Runyan, Christiane W.

    2013-01-01

    Desertification is a change in soil properties, vegetation or climate, which results in a persistent loss of ecosystem services that are fundamental to sustaining life. Desertification affects large dryland areas around the world and is a major cause of stress in human societies. Here we review recent research on the drivers, feedbacks, and impacts of desertification. A multidisciplinary approach to understanding the drivers and feedbacks of global desertification is motivated by our increasing need to improve global food production and to sustainably manage ecosystems in the context of climate change. Classic desertification theories look at this process as a transition between stable states in bistable ecosystem dynamics. Climate change (i.e., aridification) and land use dynamics are the major drivers of an ecosystem shift to a “desertified” (or “degraded”) state. This shift is typically sustained by positive feedbacks, which stabilize the system in the new state. Desertification feedbacks may involve land degradation processes (e.g., nutrient loss or salinization), changes in rainfall regime resulting from land-atmosphere interactions (e.g., precipitation recycling, dust emissions), or changes in plant community composition (e.g., shrub encroachment, decrease in vegetation cover). We analyze each of these feedback mechanisms and discuss their possible enhancement by interactions with socio-economic drivers. Large scale effects of desertification include the emigration of “environmental refugees” displaced from degraded areas, climatic changes, and the alteration of global biogeochemical cycles resulting from the emission and long-range transport of fine mineral dust. Recent research has identified some possible early warning signs of desertification, which can be used as indicators of resilience loss and imminent shift to desert-like conditions. We conclude with a brief discussion on some desertification control strategies implemented in different

  1. Preface: Multiscale feedbacks in ecogeomorphology

    USGS Publications Warehouse

    Wheaton, Joseph M.; Gibbins, Chris; Wainwright, John; Larsen, Laurel G.; McElroy, Brandon

    2011-01-01

    Geomorphic systems are known to exhibit nonlinear responses to physical–biological feedbacks (Thornes, 1985; Baas, 2002; Reinhardt et al., 2010). These responses make understanding and/or predicting system response to change highly challenging. With growing concerns over ecosystem health, a pressing need exists for research that tries to elucidate these feedbacks (Jerolmack, 2008; Darby, 2010; National Research Council, 2010). A session was convened at the Fall 2008 meeting of the American Geophysical Union (AGU) to provide an outlet for some of this truly interdisciplinary and original research, which is central to understanding geomorphic and ecological dynamics. The session attracted over 39 contributions, which were divided into two well-attended oral sessions and a very busy poster session. This special issue presents new research from the AGU session, which highlights clear physical–biological feedbacks. The aim is to bring together contrasting perspectives on biological and geomorphic feedbacks in a diversity of physiographic settings, ranging from wetlands and estuaries, through rivers, to uplands. These papers highlight biological and physical feedbacks which involve the modulation or amplification of geomorphic processes. These papers will be of interest to a core geomorphology audience, and should also draw attention from the fields of ecohydraulics, hydroecology, ecohydrology, ecomorphology, biogeochemistry and biogeography, and biogeomorphology as well as the more traditional fields of hydrology, ecology and biology. In this preface to the special issue, we a) review past contributions to the emerging field of ecogeomorphology and related disciplines, b) provide some context for how this topical special issue came to fruition, and c) summarize the contributions to this special issue.

  2. Microbial life in ridge flank crustal fluids.

    PubMed

    Huber, Julie A; Johnson, H Paul; Butterfield, David A; Baross, John A

    2006-01-01

    To determine the microbial community diversity within old oceanic crust, a novel sampling strategy was used to collect crustal fluids at Baby Bare Seamount, a 3.5 Ma old outcrop located in the north-east Pacific Ocean on the eastern flank of the Juan de Fuca Ridge. Stainless steel probes were driven directly into the igneous ocean crust to obtain samples of ridge flank crustal fluids. Genetic signatures and enrichment cultures of microorganisms demonstrate that these crustal fluids host a microbial community composed of species indigenous to the subseafloor, including anaerobic thermophiles, and species from other deep-sea habitats, such as seawater and sediments. Evidence using molecular techniques indicates the presence of a relatively small but active microbial population, dominated by bacteria. The microbial community diversity found in the crustal fluids may indicate habitat variability in old oceanic crust, with inputs of nutrients from seawater, sediment pore-water fluids and possibly hydrothermal sources. This report further supports the presence of an indigenous microbial community in ridge flank crustal fluids and advances our understanding of the potential physiological and phylogenetic diversity of this community.

  3. Jurassic zircons from the Southwest Indian Ridge.

    PubMed

    Cheng, Hao; Zhou, Huaiyang; Yang, Qunhui; Zhang, Lingmin; Ji, Fuwu; Dick, Henry

    2016-01-01

    The existence of ancient rocks in present mid-ocean ridges have long been observed but received less attention. Here we report the discovery of zircons with both reasonably young ages of about 5 Ma and abnormally old ages of approximate 180 Ma from two evolved gabbroic rocks that were dredged from the Southwest Indian Ridge (SWIR) in the Gallieni fracture zone. U-Pb and Lu-Hf isotope analyses of zircons were made using ion probe and conventional laser abrasion directly in petrographic thin sections. Young zircons and their host oxide gabbro have positive Hf isotope compositions (εHf = +15.7-+12.4), suggesting a highly depleted mantle beneath the SWIR. The spread εHf values (from-2.3 to-4.5) of abnormally old zircons, together with the unradiogenic Nd-Hf isotope of the host quartz diorite, appears to suggest an ancient juvenile magmatism along the rifting margin of the southern Gondwana prior to the opening of the Indian Ocean. A convincing explanation for the origin of the unusually old zircons is yet to surface, however, an update of the theory of plate tectonics would be expected with continuing discovery of ancient rocks in the mid-oceanic ridges and abyssal ocean basins. PMID:27185575

  4. Jurassic zircons from the Southwest Indian Ridge.

    PubMed

    Cheng, Hao; Zhou, Huaiyang; Yang, Qunhui; Zhang, Lingmin; Ji, Fuwu; Dick, Henry

    2016-05-17

    The existence of ancient rocks in present mid-ocean ridges have long been observed but received less attention. Here we report the discovery of zircons with both reasonably young ages of about 5 Ma and abnormally old ages of approximate 180 Ma from two evolved gabbroic rocks that were dredged from the Southwest Indian Ridge (SWIR) in the Gallieni fracture zone. U-Pb and Lu-Hf isotope analyses of zircons were made using ion probe and conventional laser abrasion directly in petrographic thin sections. Young zircons and their host oxide gabbro have positive Hf isotope compositions (εHf = +15.7-+12.4), suggesting a highly depleted mantle beneath the SWIR. The spread εHf values (from-2.3 to-4.5) of abnormally old zircons, together with the unradiogenic Nd-Hf isotope of the host quartz diorite, appears to suggest an ancient juvenile magmatism along the rifting margin of the southern Gondwana prior to the opening of the Indian Ocean. A convincing explanation for the origin of the unusually old zircons is yet to surface, however, an update of the theory of plate tectonics would be expected with continuing discovery of ancient rocks in the mid-oceanic ridges and abyssal ocean basins.

  5. Jurassic zircons from the Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Cheng, Hao; Zhou, Huaiyang; Yang, Qunhui; Zhang, Lingmin; Ji, Fuwu; Dick, Henry

    2016-05-01

    The existence of ancient rocks in present mid-ocean ridges have long been observed but received less attention. Here we report the discovery of zircons with both reasonably young ages of about 5 Ma and abnormally old ages of approximate 180 Ma from two evolved gabbroic rocks that were dredged from the Southwest Indian Ridge (SWIR) in the Gallieni fracture zone. U–Pb and Lu–Hf isotope analyses of zircons were made using ion probe and conventional laser abrasion directly in petrographic thin sections. Young zircons and their host oxide gabbro have positive Hf isotope compositions (εHf = +15.7–+12.4), suggesting a highly depleted mantle beneath the SWIR. The spread εHf values (from‑2.3 to‑4.5) of abnormally old zircons, together with the unradiogenic Nd-Hf isotope of the host quartz diorite, appears to suggest an ancient juvenile magmatism along the rifting margin of the southern Gondwana prior to the opening of the Indian Ocean. A convincing explanation for the origin of the unusually old zircons is yet to surface, however, an update of the theory of plate tectonics would be expected with continuing discovery of ancient rocks in the mid-oceanic ridges and abyssal ocean basins.

  6. Jurassic zircons from the Southwest Indian Ridge

    PubMed Central

    Cheng, Hao; Zhou, Huaiyang; Yang, Qunhui; Zhang, Lingmin; Ji, Fuwu; Dick, Henry

    2016-01-01

    The existence of ancient rocks in present mid-ocean ridges have long been observed but received less attention. Here we report the discovery of zircons with both reasonably young ages of about 5 Ma and abnormally old ages of approximate 180 Ma from two evolved gabbroic rocks that were dredged from the Southwest Indian Ridge (SWIR) in the Gallieni fracture zone. U–Pb and Lu–Hf isotope analyses of zircons were made using ion probe and conventional laser abrasion directly in petrographic thin sections. Young zircons and their host oxide gabbro have positive Hf isotope compositions (εHf = +15.7–+12.4), suggesting a highly depleted mantle beneath the SWIR. The spread εHf values (from−2.3 to−4.5) of abnormally old zircons, together with the unradiogenic Nd-Hf isotope of the host quartz diorite, appears to suggest an ancient juvenile magmatism along the rifting margin of the southern Gondwana prior to the opening of the Indian Ocean. A convincing explanation for the origin of the unusually old zircons is yet to surface, however, an update of the theory of plate tectonics would be expected with continuing discovery of ancient rocks in the mid-oceanic ridges and abyssal ocean basins. PMID:27185575

  7. Melt Flux Around Iceland: The Kolbeinsey Ridge Seismic Experiment.

    NASA Astrophysics Data System (ADS)

    Brandsdóttir, B.; Hooft, E. E.

    2007-12-01

    Seafloor spreading within the Iceland region has been complex since the opening of the North Atlantic in late Paleocene-early Eocene. Whereas symmetric magnetic anomalies can be traced parallel to the Reykjanes Ridge and Mohns Ridge back to chrons 23-24, anomalies within the Iceland Plateau and Aegir Ridge in the Norwegian Sea, as well as along the Greenland-Iceland-Faeroe Ridge reflect plate-boundary irregularities associated with multiple-branched crustal accretion zones, rift jumps and plate boundary segmentation (volcanic systems). We observe large variations in crustal structure along two refraction/reflection/gravity profiles, a 700 km EW-profile straddling 66.5°N between the Aegir and Kolbeinsey Ridges and a 225 km NS-profile along the southern Kolbeinsey Ridge. These profiles enable us to quantify how melt flux at the N-Atlantic spreading center has been influenced by the Iceland hotspot from the initiation of spreading to present time. The westernmost 300 km of the EW profile lies across the Iceland shelf, considered to have formed by rifting at the Kolbeinsey Ridge whereas the easternmost 400 km lie across the Iceland Plateau and Norway Basin, a region formed by rifting at the Aegir Ridge and possibly containing slivers of older crust rifted off the east Greenland margin along with the Jan Mayen Ridge. Crustal thickness varies from 4-5 km across the Aegir Ridge, 12 km just east of the Iceland shelf, and 24-28 km beneath the outer shelf, to 12-13 km near the southern tip of the Kolbeinsey Ridge and 9-10 km further north along the ridge axis. Pronounced undulations in lower crustal structure across the Iceland Plateau are most likely associated with extinct spreading centers indicating that branched crustal accretion zones existed west of the Aegir Ridge prior to the westward ridge jump forming the KR at 26 Ma. Crustal thickness at the Kolbeinsey and Reykjanes Ridges support the asymmetry in plume-ridge interaction north and south of Iceland that has been

  8. Variations in Mid-Ocean Ridge CO2 Emissions Driven By Glacial Cycles

    NASA Astrophysics Data System (ADS)

    Burley, J. M.; Katz, R. F.; Huybers, P. J.

    2014-12-01

    Glacial cycles impact continental volcanism through pressure changes associated with growth and retreat of ice sheets [e.g. Iceland - Jull, 1996]. Similarly, changes in sea level accompanying glacial cycles modulate mid-ocean ridge (MOR) volcanism by pressure changes and their influence on melt production [Crowley 2014; Lund 2011; Huybers 2009]. CO2 transport through the upper mantle is sensitive to mantle melting because CO2 partitions completely into the melt phase when present. Melt then transports CO2 to the ridge axis, where it enters the climate system. We present models of CO2 transport that investigate how sea level modulates the rate of CO2 emission from MORs. The total carbon reservoir in the mantle is circa 10^7 GtC [Dasgupta 2010], orders of magnitude more than the oceans (40,000 GtC) and atmosphere (600 GtC). Changes in the rate of CO2 emission from the solid Earth therefore have the potential to significantly affect the surface carbon system. We have developed an analytical model of CO2 transport from the depth of first silicate melting (~60km) to the ridge axis, enabling a calculation of CO2 emission rate for a generic section of MOR. The model assumes homogeneous mantle and energy-conserving melt production from a simplified 2-component mantle; CO2 is taken as a perfectly incompatible trace element. Pressure variations modulate the depth of initial silicate melting and hence the flux of CO2 into the melting regime. The model can also be applied to any species that is strongly partitioned into the melt (eg. Uranium, Thorium, Niobium, Barium, Rubidium). Results suggest that changing sea level over the past Myr could have altered the CO2 emissions from MOR by ~8%. The magnitude of variation in emissions is sensitive to the mantle permeability, the ridge spreading rate, and the rate of change of sea level. The travel time of melt through the mantle causes a delay between sea-level change and the CO2 response of the MOR. This delay is sensitive to plate

  9. Biogeochemical patchiness, geomorphic feedbacks, and flow connectivity in river-floodplain corridors

    NASA Astrophysics Data System (ADS)

    Larsen, L.; Harvey, J. W.; Maglio, M.

    2014-12-01

    Ecogeomorphology is the understanding of the signature of life on landforms. The field has advanced primarily on the basis of studies of physical-biological feedbacks between vegetation, flow, and sediment transport. However, biogeochemistry also has the potential to exert strong feedback on life and landforms. This potential is particularly high in tropical and subtropical regions, where vegetation is often phosphorus (P)-limited. Aquatic landscapes are essentially closed systems for P—in contrast to nitrogen—and the transport of P primarily in particulate form can establish a tight feedback between biogeochemical and geomorphic processes in these regions. Here we examine mechanisms that can contribute to spatial patterning, or patchiness, in nutrient distributions and vegetated landforms. We evaluated hypotheses for evapotranspiration focusing, differential hydrologic exchange, and particulate nutrient redistribution mechanisms to explain spatial patterns of P retention and function of the Everglades. Based on field measurements in sloughs and on slightly higher and more densely vegetated ridges and field-grounded mechanistic models, we quantified P fluxes attributable to the three mechanisms. Findings suggest that evapotranspiration focusing is not a driver of Everglades nutrient retention nor of ridge and slough patterning. Instead, differential hydrologic exchange, driven by different periods of groundwater-surface water connectivity across topographic elements, is the primary cause of elevated P concentrations on ridges and can completely explain interpatch differences in long-term P accumulation rates. With historical flow velocities, which were an order of magnitude higher than at present, particulate P redistribution would have further increased the interpatch difference in long-term P retention rates nearly twofold, with potential consequences for landscape pattern development. In conclusion, differential hydrologic exchange and particulate nutrient

  10. Investigating Shareable Feedback Tags for Programming Assignments

    ERIC Educational Resources Information Center

    Cummins, Stephen; Burd, Liz; Hatch, Andrew

    2011-01-01

    This article presents an investigation into the usage of shareable feedback tags as a way of delivering feedback to three different cohorts of programming students. A series of research questions are examined; these include investigating any perceived benefit from students using feedback tags and exploring how students interact with their…

  11. Simple Optoelectronic Feedback in Microwave Oscillators

    NASA Technical Reports Server (NTRS)

    Maleki, Lute; Iltchenko, Vladimir

    2009-01-01

    A proposed method of stabilizing microwave and millimeter-wave oscillators calls for the use of feedback in optoelectronic delay lines characterized by high values of the resonance quality factor (Q). The method would extend the applicability of optoelectronic feedback beyond the previously reported class of optoelectronic oscillators that comprise two-port electronic amplifiers in closed loops with high-Q feedback circuits.

  12. Effective Feedback Design Using Free Technologies

    ERIC Educational Resources Information Center

    Yuan, Jiangmei; Kim, ChanMin

    2015-01-01

    Feedback plays a critical role in student learning and performance. However, providing students with effective feedback is challenging in online environments because of physical separation between students and instructors. Technologies can be used to enhance the effectiveness of feedback in online courses. In this article, we propose effective…

  13. Feedback Sandwiches Affect Perceptions but Not Performance

    ERIC Educational Resources Information Center

    Parkes, Jay; Abercrombie, Sara; McCarty, Teresita

    2013-01-01

    The feedback sandwich technique-make positive comments; provide critique; end with positive comments-is commonly recommended to feedback givers despite scant evidence of its efficacy. These two studies (N = 20; N = 350) of written peer feedback with third-year medical students on clinical patient note-writing assignments indicate that students…

  14. Engaging Students with Feedback through Adaptive Release

    ERIC Educational Resources Information Center

    Irwin, Brian; Hepplestone, Stuart; Holden, Graham; Parkin, Helen J.; Thorpe, Louise

    2013-01-01

    Feedback to students has been highlighted in the literature as an area where improvements are needed. Students need high quality, prompt feedback, but they also need guidance and tools to help them engage with and learn from that feedback. This case study explores staff and student perceptions of a tool at Sheffield Hallam University which…

  15. The Impact of Feedback Training for Inspectors

    ERIC Educational Resources Information Center

    Dobbelaer, Marjoleine J.; Prins, Frans J.; van Dongen, Dre

    2013-01-01

    Purpose: The purpose of this paper is to explore whether oral feedback by inspectors of the Dutch Inspectorate of Education is an adequate method to support the professional development of teachers in primary education. This study aims to examine the impact of short feedback training for inspectors (focused on effective feedback conversations) on…

  16. Feedback and the Reconstruction of Meaning.

    ERIC Educational Resources Information Center

    Langer, Philip; And Others

    This investigation of the impact of feedback upon scrambled discourse was intended to show the effects of idiosyncratic processing and to provide a more sensitive indicator of feedback usefulness. Learner schemata, text organization, and feedback strategies interact in processing discourse, although past research has favored limited models…

  17. The Effects of Feedback as Interpersonal Reciprocities

    ERIC Educational Resources Information Center

    Levenstein, Joseph; And Others

    1977-01-01

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

  18. A Survey of Psychological Assessment Feedback Practices

    ERIC Educational Resources Information Center

    Smith, Steven R.; Wiggins, Chauntel M.; Gorske, Tad T.

    2007-01-01

    There have been no previous studies on how often psychologists conduct feedback and whether they view this practice as a useful component of assessment. To explore psychologists' feedback practices and their perception of the effects of feedback on their clients, the authors examined survey data from 719 psychologist members of the International…

  19. Changing Teachers' Feedback Practices: A Workshop Challenge

    ERIC Educational Resources Information Center

    Fonseca, Jesuína; Carvalho, Carolina; Conboy, Joseph; Valente, Maria Odete; Gama, Ana Paula; Salema, Maria Helena; Fiúza, Edite

    2015-01-01

    Feedback can promote teacher-student relations and student academic involvement, performance and self-regulation. However, some research indicates that teachers do not always employ feedback effectively. There is a need to promote teachers' appropriate use of feedback in the classroom. We describe a long-term workshop designed to enhance teachers'…

  20. The Courage to Seek Authentic Feedback

    ERIC Educational Resources Information Center

    Wiggins, Alexis

    2011-01-01

    Educators assess students' work and behavior every day. They are professional feedback-givers, dispensing grades, advice, support, and red ink. They believe in the power of feedback to communicate what students are doing well and how they can do better. However, some teachers shy away from opportunities for feedback on their own work. Some don't…

  1. Cost Analysis, Evaluation and Feedback. Symposium.

    ERIC Educational Resources Information Center

    2002

    This document contains four papers from a symposium on cost analysis, evaluation, and feedback in human resource development. "Training Evaluation with 360-Degree Feedback" (Froukje A. Jellema) reports on a quasi-experimental study that examined the effectiveness of 360-degree feedback in evaluating the training received by nurses in a Dutch…

  2. The Art of Giving Online Feedback

    ERIC Educational Resources Information Center

    Leibold, Nancyruth; Schwarz, Laura Marie

    2015-01-01

    The cultivation of providing online feedback that is positive, effective, and enhances the learning experience is a valuable educator skill. Acquisition of the art of providing feedback is through education, practice, and faculty development. This article provides information about the best practices for delivering online feedback to learners. An…

  3. The Problem of Feedback in Hearing Aids.

    ERIC Educational Resources Information Center

    Kates, James M.

    1991-01-01

    This paper discusses the problem of feedback in hearing aids and offers examples based on a computer simulation of hearing aid behavior. The available technology for dealing with feedback is reviewed, and the new digital signal-processing approaches which may finally solve the feedback problem are described. (Author/DB)

  4. Effectiveness of Feedback: The Students' Perspective

    ERIC Educational Resources Information Center

    Poulos, Ann; Mahony, Mary Jane

    2008-01-01

    While effective feedback has frequently been identified as a key strategy in learning and teaching, little known research has focused on students' perceptions of feedback and the contribution feedback makes to students' learning and teaching. This reported qualitative study aims to enrich our understanding of these perceptions and importantly to…

  5. Chat-Line Interaction and Negative Feedback.

    ERIC Educational Resources Information Center

    Iwasaki, Junko; Oliver, Rhonda

    2003-01-01

    Examines communicative interactions between native speakers (NSs) and nonnative speakers (NNSs) of Japanese on Internet relay chat, with a special focus on implicit negative feedback in the interactions. Reports that NSs of Japanese gave implicit negative feedback to their NNS partners and NNSs used the feedback in their subsequent production, but…

  6. Feedback loop compensates for rectifier nonlinearity

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Signal processing circuit with two negative feedback loops rectifies two sinusoidal signals which are 180 degrees out of phase and produces a single full-wave rectified output signal. Each feedback loop incorporates a feedback rectifier to compensate for the nonlinearity of the circuit.

  7. Adaptation to delayed auditory feedback

    NASA Technical Reports Server (NTRS)

    Katz, D. I.; Lackner, J. R.

    1977-01-01

    Delayed auditory feedback disrupts the production of speech, causing an increase in speech duration as well as many articulatory errors. To determine whether prolonged exposure to delayed auditory feedback (DAF) leads to adaptive compensations in speech production, 10 subjects were exposed in separate experimental sessions to both incremental and constant-delay exposure conditions. Significant adaptation occurred for syntactically structured stimuli in the form of increased speaking rates. After DAF was removed, aftereffects were apparent for all stimulus types in terms of increased speech rates. A carry-over effect from the first to the second experimental session was evident as long as 29 days after the first session. The use of strategies to overcome DAF and the differences between adaptation to DAF and adaptation to visual rearrangement are discussed.

  8. Haptic feedback for multilayer cutting.

    PubMed

    Rianto, Sugeng; Li, Ling; Hartley, Bruce

    2008-01-01

    An approach in effectively estimating the force feedback for a tactile haptic based on multi-proxy rendering for 3D surface cuttings for a virtual surgery simulation is described in this paper. The force-models representing haptic force-feedback are approximated using D'Alembert's principle in the mechanic case of spring-damper-stiffness interaction of the surfaces. We also propose a combination between mesh refinement and adaptive re-meshing to create a progressive cutting over the layering surfaces. Experimental results prove that the physical interaction to create cutting paths over the multilayer surfaces can be deliver smoothly with haptic in real time with 3D visual stereo on a PC.

  9. Feedback control of resistive instabilities

    SciTech Connect

    White, R.B.; Rutherford, P.H.; Furth, H.P.; Park, W.; Chen, L.

    1985-12-01

    Resistive instabilities are responsible for much of the global behavior and the determination of the possible domains of operation of tokamaks. Their successful control could have definite advantages, even making available new regimes of operation. Elimination of sawtoothing might allow operation with higher currents and more peaked current profiles, with q on axis well below unity. In this work different feedback schemes are explored. Simple analytical derivations of the effects of local heating and current drive feedback are presented. Although control of modes with m greater than or equal to 2 is fairly straightforward, the control of the m = 1 mode is more difficult because of its proximity to ideal instability. The most promising scheme utilizes high energy trapped particles. 20 refs., 3 figs.

  10. Feedback type variable venturi carburetor

    SciTech Connect

    Morino, T.; Takada, S.; Takeuchi, Y.

    1982-02-09

    A feedback type variable venturi carburetor in which the negative pressure regulated by the variable venturi at a constant level is supplied to a solenoid valve which is opened and closed at a frequency of 5-30 hz and whose open-close time ratio is controlled in accordance with the signal from exhaust gas sensor to control the vacuum pressure applied to a diaphragm chamber of an air-bleed flow control means thereby controlling the air-fuel ratio of the mixture at an optimum level. This invention obviates the use of a regulator for regulating the negative pressure from the intake manifold and precludes the drawbacks experienced with conventional carburetors, such as the slow response in the feedback control caused when the main fuel system and the idling system of the conventional carburetor are switched over, and the unstable supply of fuel when the fuel begins to be delivered from the main fuel system.

  11. Hydrothermal Activity on ultraslow Spreading Ridge: new hydrothermal fields found on the Southwest Indian ridge

    NASA Astrophysics Data System (ADS)

    Tao, C.; Li, H.; Deng, X.; Lei, J.; Wang, Y.; Zhang, K.; Zhou, J.; Liu, W.

    2014-12-01

    Ultraslow spreading ridge makes up about 25% of global mid-ocean ridge length. Previous studies believed that hydrothermal activity is not widespread on the ultraslow spreading ridge owing to lower magma supply. Southwest Indian ridge (SWIR) with the spreading rate between 1.2cm/a to 1.4cm/a, represents the ultraslow spreading ridge. In 2007, Chinese Cruise (CC) 19th discovered the Dragon Flag deposit (DFD) on the SWIR, which is the first active hydrothermal field found on the ultraslow spreading ridge. In recent years, over 10 hydrothermal fields have been found on the SWIR between Indomed and Gallieni transform faults by the Chinese team. Tao et al. (2012) implied that the segment sections with excess heat from enhanced magmatism and suitable crustal permeability along slow and ultraslow ridges might be the most promising areas for searching for hydrothermal activities. In 2014, CC 30thdiscovered five hydrothermal fields and several hydrothermal anomalies on the SWIR. Dragon Horn Area (DHA). The DHA is located on the southern of segment 27 SWIR, with an area of about 400 km2. The geophysical studies indicated that the DHA belongs to the oceanic core complex (OCC), which is widespread on the slow spreading ridges (Zhao et al., 2013). The rocks, such as gabbro, serpentinized peridotite, and consolidated carbonate were collected in the DHA, which provide the direct evidence with the existence of the OCC. However, all rock samples gathered by three TV-grab stations are basalts on the top of the OCC. A hydrothermal anomaly area, centered at 49.66°E,37.80° S with a range of several kms, is detected in the DHA. It is probably comprised of several hydrothermal fields and controlled by a NW fault. New discovery of hydrothermal fields. From January to April 2014, five hydrothermal fields were discovered on the SWIR between 48°E to 50°E during the leg 2&3 of the CC 30th, which are the Su Causeway field (48.6°E, 38.1°S), Bai Causeway field (48.8°E, 37.9 °S), Dragon

  12. Physiological Feedback Method and System

    NASA Technical Reports Server (NTRS)

    Pope, Alan T. (Inventor); Severance, Kurt E. (Inventor)

    2002-01-01

    A method and system provide physiological feedback for a patient and/or physician. At least one physiological effect experienced by a body part of a patient is measured noninvasively. A three-dimensional graphics model serving as an analogous representation of the body part is altered in accordance with the measurements. A binocular image signal representative of the three-dimensional graphics model so-altered is displayed for the patient and/or physician in a virtual reality environment.

  13. Comparing Simulations of AGN Feedback

    NASA Astrophysics Data System (ADS)

    Richardson, Mark L. A.; Scannapieco, Evan; Devriendt, Julien; Slyz, Adrianne; Thacker, Robert J.; Dubois, Yohan; Wurster, James; Silk, Joseph

    2016-07-01

    We perform adaptive mesh refinement (AMR) and smoothed particle hydrodynamics (SPH) cosmological zoom simulations of a region around a forming galaxy cluster, comparing the ability of the methods to handle successively more complex baryonic physics. In the simplest, non-radiative case, the two methods are in good agreement with each other, but the SPH simulations generate central cores with slightly lower entropies and virial shocks at slightly larger radii, consistent with what has been seen in previous studies. The inclusion of radiative cooling, star formation, and stellar feedback leads to much larger differences between the two methods. Most dramatically, at z=5, rapid cooling in the AMR case moves the accretion shock to well within the virial radius, while this shock remains near the virial radius in the SPH case, due to excess heating, coupled with poorer capturing of the shock width. On the other hand, the addition of feedback from active galactic nuclei (AGNs) to the simulations results in much better agreement between the methods. For our AGN model, both simulations display halo gas entropies of 100 keV cm2, similar decrements in the star formation rate, and a drop in the halo baryon content of roughly 30%. This is consistent with the AGN growth being self-regulated, regardless of the numerical method. However, the simulations with AGN feedback continue to differ in aspects that are not self-regulated, such that in SPH a larger volume of gas is impacted by feedback, and the cluster still has a lower entropy central core.

  14. Logistic systems with linear feedback

    NASA Astrophysics Data System (ADS)

    Son, Leonid; Shulgin, Dmitry; Ogluzdina, Olga

    2016-08-01

    A wide variety of systems may be described by specific dependence, which is known as logistic curve, or S-curve, between the internal characteristic and the external parameter. Linear feedback between these two values may be suggested for a wide set of systems also. In present paper, we suggest a bifurcation behavior for systems with both features, and discuss it for two cases, which are the Ising magnet in external field, and the development of manufacturing enterprise.

  15. Rf feedback free electron laser

    DOEpatents

    Brau, C.A.; Swenson, D.A.; Boyd, T.J. Jr.

    1979-11-02

    A free electron laser system and electron beam system for a free electron laser are provided which use rf feedback to enhance efficiency. Rf energy is extracted from an electron beam by decelerating cavities and returned to accelerating cavities using rf returns such as rf waveguides, rf feedthroughs, etc. This rf energy is added to rf klystron energy to lower the required input energy and thereby enhance energy efficiency of the system.

  16. Rf Feedback free electron laser

    DOEpatents

    Brau, Charles A.; Swenson, Donald A.; Boyd, Jr., Thomas J.

    1981-01-01

    A free electron laser system and electron beam system for a free electron laser which use rf feedback to enhance efficiency. Rf energy is extracted from an electron beam by decelerating cavities and returned to accelerating cavities using rf returns such as rf waveguides, rf feedthroughs, etc. This rf energy is added to rf klystron energy to lower the required input energy and thereby enhance energy efficiency of the system.

  17. Tailoring Feedback: Effective Feedback Should Be Adjusted Depending on the Needs of the Learner

    ERIC Educational Resources Information Center

    Brookhart, Susan M.

    2011-01-01

    All students deserve effective feedback. General principles for effective feedback should be adjusted depending on the learner's needs. Feedback to struggling students should include focusing on the process, selecting only one or just a few points, giving self-referenced feedback to describe progress or capability, being very clear, and checking…

  18. Students' Feedback Preferences: How Do Students React to Timely and Automatically Generated Assessment Feedback?

    ERIC Educational Resources Information Center

    Bayerlein, Leopold

    2014-01-01

    This study assesses whether or not undergraduate and postgraduate accounting students at an Australian university differentiate between timely feedback and extremely timely feedback, and whether or not the replacement of manually written formal assessment feedback with automatically generated feedback influences students' perception of…

  19. Probabilistic models for feedback systems.

    SciTech Connect

    Grace, Matthew D.; Boggs, Paul T.

    2011-02-01

    In previous work, we developed a Bayesian-based methodology to analyze the reliability of hierarchical systems. The output of the procedure is a statistical distribution of the reliability, thus allowing many questions to be answered. The principal advantage of the approach is that along with an estimate of the reliability, we also can provide statements of confidence in the results. The model is quite general in that it allows general representations of all of the distributions involved, it incorporates prior knowledge into the models, it allows errors in the 'engineered' nodes of a system to be determined by the data, and leads to the ability to determine optimal testing strategies. In this report, we provide the preliminary steps necessary to extend this approach to systems with feedback. Feedback is an essential component of 'complexity' and provides interesting challenges in modeling the time-dependent action of a feedback loop. We provide a mechanism for doing this and analyze a simple case. We then consider some extensions to more interesting examples with local control affecting the entire system. Finally, a discussion of the status of the research is also included.

  20. Distributed-feedback Terahertz Quantum-cascade Lasers with Laterally Corrugated Metal Waveguides

    NASA Technical Reports Server (NTRS)

    Williams, Benjamin S.; Kumar, Sushil; Hu, Qing; Reno, John L.

    2005-01-01

    We report the demonstration of distributed-feedback terahertz quantum-cascade lasers based on a first-order grating fabricated via a lateral corrugation in a double-sided metal ridge waveguide. The phase of the facet reflection was precisely set by lithographically defined facets by dry etching. Single-mode emission was observed at low to moderate injection currents, although multimode emission was observed far beyond threshold owing to spatial hole burning. Finite-element simulations were used to calculate the modal and threshold characteristics for these devices, with results in good agreement with experiments.

  1. Magnetic Anomalies over the Pacific-Antarctic Ridge.

    PubMed

    Pitman, W C; Heirtzler, J R

    1966-12-01

    Four magnetic profiles across the Pacific-Antarctic Ridge reveal magnetic anomalies that show trends parallel with the ridge axis and symmetry about the ridge axis. The distribution of bodies that could cause these anomalies supports the Vine and Matthews hypothesis for the generation of patterns of magnetic anomalies associated with the midocean ridge system. The geometry of the bodies accords with the known reversals of the geomagnetic field during the last 3.4 million years, indicating a spreading rate of the ocean floor of 4.5 centimeters per year. If one assume that the spreading rate within 500 kilometers of the ridge axis has been constant, reversals of the geomagnetic field during the last 10.0 million years can be determined. This new, detailed history of field reversals accords with observed anomalies over Reykjanes Ridge in the North Atlantic if a spreading rate of 1 centimeter per year is assumed there.

  2. Dynamical instability produces transform faults at mid-ocean ridges.

    PubMed

    Gerya, Taras

    2010-08-27

    Transform faults at mid-ocean ridges--one of the most striking, yet enigmatic features of terrestrial plate tectonics--are considered to be the inherited product of preexisting fault structures. Ridge offsets along these faults therefore should remain constant with time. Here, numerical models suggest that transform faults are actively developing and result from dynamical instability of constructive plate boundaries, irrespective of previous structure. Boundary instability from asymmetric plate growth can spontaneously start in alternate directions along successive ridge sections; the resultant curved ridges become transform faults within a few million years. Fracture-related rheological weakening stabilizes ridge-parallel detachment faults. Offsets along the transform faults change continuously with time by asymmetric plate growth and discontinuously by ridge jumps. PMID:20798313

  3. Dynamical instability produces transform faults at mid-ocean ridges.

    PubMed

    Gerya, Taras

    2010-08-27

    Transform faults at mid-ocean ridges--one of the most striking, yet enigmatic features of terrestrial plate tectonics--are considered to be the inherited product of preexisting fault structures. Ridge offsets along these faults therefore should remain constant with time. Here, numerical models suggest that transform faults are actively developing and result from dynamical instability of constructive plate boundaries, irrespective of previous structure. Boundary instability from asymmetric plate growth can spontaneously start in alternate directions along successive ridge sections; the resultant curved ridges become transform faults within a few million years. Fracture-related rheological weakening stabilizes ridge-parallel detachment faults. Offsets along the transform faults change continuously with time by asymmetric plate growth and discontinuously by ridge jumps.

  4. En Echelon Ridge and Trough Structures on Europa

    NASA Technical Reports Server (NTRS)

    Michalski, Joseph R.; Greeley, Ronald

    2002-01-01

    Europa#s surface is tectonically and morphologically complex. Europan ridges, bands, ridged bands, double ridges, complex ridges, and troughs are collectively referred to as lineaments. Some lineaments are fault zones and exhibit sets of en echelon ridge and trough structures (EERTS). EERTS can be used to interpret the stress field in which the lineaments formed. These observations suggest that some lineaments at low latitudes initially formed as shear zones. rather than as purely tensional fractures as is commonly assumed. From stepping directions of EERTS and the offset directions of the lineaments in which they occur, we infer that some EERTS form as a result of compressional stress and others form as a result of tensional stress. EERTS that are inferred to form in compression are morphologically indistinguishable from EERTS that form in tension. The presence of tensional EERTS may support a diapiric origin for some ridges.

  5. Chemical feedbacks in climate sensitivity studies

    NASA Astrophysics Data System (ADS)

    Dietmüller, Simone; Ponater, Michael; Sausen, Robert

    2013-04-01

    Interactively coupled climate chemistry models extend the number of feedback mechanisms in climate change simulations by allowing a variation of several radiatively actice chemical tracers that are prescribed in conventional climate models. Different perturbation experiments including chemical feedbacks were performed using the chemistry-climate model system EMAC coupled to the mixed layer ocean model MLO. The influence of the chemical feedbacks O3, CH4 and N2O on climate response and climate sensitivity is quantified for a series of CO2-perturbation simulations: Equilibrium climate sensitivity is dampened, if chemical feedbacks are included. In case of a CO2 doubling simulation chemical feedbacks decrease climate sensitivity by -3.6% and in case of a 4*CO2 simulation by -8.1%. Analysis of the chemical feedbacks reveals, that the negative feedback of ozone, mainly the feedback of stratospheric ozone, is responsible for this dampening. The radiative feedbacks of CH4 and N2O are negligible, mainly because the model system does not allow interactive emission feedbacks at the Earth's surface for these gases. The feedback of physical parameters is significantly modified by the presence of chemical feedbacks. In case of the CO2-perturbation experiments the negative stratospheric ozone feedback is accompanied by a negative stratospheric H2O feedback change of the same order of magnitude. So the dampening effect of the direct O3 radiative feedback is enhanced. A non-linearity in the damping is found with increasing CO2 concentrations. Reasons are the nonlinear feedbacks of ozone, temperature, and stratospheric water vapor. Additional 6*CO2 simulations with and without chemical feedbacks included show, that the presence of chemic feedbacks helps to prevent a runaway greenhouse effect, as the O3 distribution can react to the upward shift of the tropopause. Also experiments driven by anthropogenic NOx- and CO-emissions were performed, where chemically active trace gases act

  6. Constructivist coding: learning from selective feedback.

    PubMed

    Elwin, Ebba; Juslin, Peter; Olsson, Henrik; Enkvist, Tommy

    2007-02-01

    Although much learning in real-life environments relies on highly selective feedback about outcomes, virtually all cognitive models of learning, judgment, and categorization assume complete and representative feedback. We investigated empirically the effect of selective feedback on decision making and how people code experience with selective feedback. The results showed that, in contrast to a commonly raised concern, performance was not impaired following learning with selective and biased feedback. Furthermore, even in a simple decision task, the experience that people acquired was not a mere recording of the observed outcomes, but rather a reconstruction from general task knowledge. PMID:17425527

  7. Realizing actual feedback control of complex network

    NASA Astrophysics Data System (ADS)

    Tu, Chengyi; Cheng, Yuhua

    2014-06-01

    In this paper, we present the concept of feedbackability and how to identify the Minimum Feedbackability Set of an arbitrary complex directed network. Furthermore, we design an estimator and a feedback controller accessing one MFS to realize actual feedback control, i.e. control the system to our desired state according to the estimated system internal state from the output of estimator. Last but not least, we perform numerical simulations of a small linear time-invariant dynamics network and a real simple food network to verify the theoretical results. The framework presented here could make an arbitrary complex directed network realize actual feedback control and deepen our understanding of complex systems.

  8. [360-degree feedback for medical trainees].

    PubMed

    Holm, Ellen; Holm, Kirsten; Sørensen, Jette Led

    2014-12-01

    In 360-degree feedback medical colleagues and collaborators give a trainee feedback by answering a questionnaire on behaviour of the trainee. The questionnaire may contain questions answered on a scale or/and they may contain open questions. The result from 360-degree feedback is used for formative feedback and assessment. In order to secure reliability 8-15 respondents are needed. It is a matter of discussion whether the respondents should be chosen by the trainee or by a third part, and if respondents should be anonymous. The process includes a feedback session with a trained supervisor.

  9. Field Use of NMIS at Oak Ridge

    SciTech Connect

    Chiang, L.G.; Conger, M.; Hughes, S.S.; Mattingly, J.K.; McEvers, J.A.; Mihalczo, J.T.; Mullens, J.A.; Perez, R.B.; Turner, C.R.; Uckan, T.; Valentine, T.E.

    1999-08-26

    The Nuclear Materials Identification System (NMIS), developed by the Oak Ridge National Laboratory and Oak Ridge Y-12 Plant (Y-12), has been successfully used at Y-12 for nuclear material control and accountability (NMC&A). It is particularly useful in the high gamma-ray background of storage arrays and for shielded HEU. With three systems in use at Y-12, NMIS has enhanced the NMC&A capability for verification and for confirmation of materials in storage and for HEU receipts by providing capability not available or practical by other NDA methods for safeguards. It has recently cost-effectively quantified the HEU mass and enrichment of hundreds of HEU metal items to within a total spread of {+-} 5% (3 sigma) with and mean deviations for all HEU verified of + 0.2% for mass and {minus}0.2% for enrichment. Three cart portable systems are easily moved around with minimal impact on facility operations since no permanent dedicated floor space is required. The positive impact of NMIS at the Oak Ridge Y-12 Plant is improved and more cost effective NMC&A as well as the resolution of NMC&A findings. Its operation at the Y-12 Plant is essential for compliance with the NMC&A requirements of the US Department of Energy. NMIS portability has allowed one system to be moved temporarily to the former K-25 Gaseous Diffusion Plant for characterization of a large deposit of hydrated uranyl fluoride. The impact of this NMIS application was enhanced and verified nuclear criticality safety that led to the safe removal of a large deposit originally estimated by gamma-ray spectrometry and neutron counting to contain 1300 kg of 3.3 wt% {sup 235}U material. NMIS has also been operational at Los Alamos National Laboratory and Pantex.

  10. Feedback control and output feedback control for the stabilisation of switched Boolean networks

    NASA Astrophysics Data System (ADS)

    Li, Fangfei; Yu, Zhaoxu

    2016-02-01

    This paper presents the feedback control and output feedback control for the stabilisation of switched Boolean network. A necessary condition for the existence of a state feedback controller for the stabilisation of switched Boolean networks under arbitrary switching signal is derived first, and constructive procedures for feedback control and output feedback control design are provided. An example is introduced to show the effectiveness of this paper.

  11. Oak Ridge Reservation environmental report for 1991

    SciTech Connect

    Mucke, P.C.

    1992-10-01

    The first two volumes of this report present data and supporting narratives regarding the impact of the US Department of Energy's (DOE's) Oak Ridge Reservation (ORR) on its surrounding environs and the public during 1991. Volume 1 includes all narrative descriptions, summaries, and conclusions and is intended to be a stand-alone'' report for the reader who does not want to review in detail all of the 1991 data for the ORR. This volume, Volume 2, includes the detailed data formats that ensure all the environmental data are represented. Narratives are not included. The information in Vol. 2 is addressed and analyzed in Vol. 1.

  12. Oak Ridge Leadership Computing Facility Position Paper

    SciTech Connect

    Oral, H Sarp; Hill, Jason J; Thach, Kevin G; Podhorszki, Norbert; Klasky, Scott A; Rogers, James H; Shipman, Galen M

    2011-01-01

    This paper discusses the business, administration, reliability, and usability aspects of storage systems at the Oak Ridge Leadership Computing Facility (OLCF). The OLCF has developed key competencies in architecting and administration of large-scale Lustre deployments as well as HPSS archival systems. Additionally as these systems are architected, deployed, and expanded over time reliability and availability factors are a primary driver. This paper focuses on the implementation of the Spider parallel Lustre file system as well as the implementation of the HPSS archive at the OLCF.

  13. Environmental baseline survey report for West Black Oak Ridge, East Black Oak Ridge, McKinney Ridge, West Pine Ridge and parcel 21D in the vicinity of the East Technology Park, Oak Ridge, Tennessee

    SciTech Connect

    King, David A.

    2012-11-29

    This environmental baseline survey (EBS) report documents the baseline environmental conditions of five land parcels located near the U.S. Department of Energy?s (DOE?s) East Tennessee Technology Park (ETTP), including West Black Oak Ridge, East Black Oak Ridge, McKinney Ridge, West Pine Ridge, and Parcel 21d. Preparation of this report included the detailed search of federal government records, title documents, aerial photos that may reflect prior uses, and visual inspections of the property and adjacent properties. Interviews with current employees involved in, or familiar with, operations on the real property were also conducted to identify any areas on the property where hazardous substances and petroleum products, or their derivatives, and acutely hazardous wastes may have been released or disposed. In addition, a search was made of reasonably obtainable federal, state, and local government records of each adjacent facility where there has been a release of any hazardous substance or any petroleum product or their derivatives, including aviation fuel and motor oil, and which is likely to cause or contribute to a release of any hazardous substance or any petroleum product or its derivatives, including aviation fuel or motor oil, on the real property. A radiological survey and soil/sediment sampling was conducted to assess baseline conditions of Parcel 21d that were not addressed by the soils-only no-further-investigation (NFI) reports. Groundwater sampling was also conducted to support a Parcel 21d decision. Based on available data West Black Oak Ridge, East Black Oak Ridge, McKinney Ridge, and West Pine Ridge are not impacted by site operations and are not subject to actions per the Federal Facility Agreement (FFA). This determination is supported by visual inspections, records searches and interviews, groundwater conceptual modeling, approved NFI reports, analytical data, and risk analysis results. Parcel 21d data, however, demonstrate impacts from site

  14. Comparing two methods of delivering neuropsychological feedback.

    PubMed

    Fallows, Robert R; Hilsabeck, Robin C

    2013-03-01

    Feedback methods have been studied in medical and psychotherapy settings, but limited research is available in neuropsychology. The purpose of this study was to examine whether supplementing oral feedback with written information would lead to greater retention of information and improved adherence to recommendations. Seventy-two veterans were enrolled in the study and randomized to receive oral feedback only or oral feedback with written information. The participants were then interviewed immediately after feedback and 1 month later by phone. Univariate analyses revealed that the written group freely recalled more recommendations at the phone interview; however, there were no differences in recall of diagnostic information or the number of recommendations attempted. Findings indicate that receiving supplemental written information improves recall of recommendations and that patients prefer to receive written information in addition to oral feedback. Recommendations to improve the retention of feedback information are discussed. PMID:23315402

  15. Comprehensive integrated planning: A process for the Oak Ridge Reservation, Oak Ridge, Tennessee

    SciTech Connect

    1998-05-01

    The Oak Ridge Comprehensive Integrated Plan is intended to assist the US Department of Energy (DOE) and contractor personnel in implementing a comprehensive integrated planning process consistent with DOE Order 430.1, Life Cycle Asset Management and Oak Ridge Operations Order 430. DOE contractors are charged with developing and producing the Comprehensive Integrated Plan, which serves as a summary document, providing information from other planning efforts regarding vision statements, missions, contextual conditions, resources and facilities, decision processes, and stakeholder involvement. The Comprehensive Integrated Plan is a planning reference that identifies primary issues regarding major changes in land and facility use and serves all programs and functions on-site as well as the Oak Ridge Operations Office and DOE Headquarters. The Oak Ridge Reservation is a valuable national resource and is managed on the basis of the principles of ecosystem management and sustainable development and how mission, economic, ecological, social, and cultural factors are used to guide land- and facility-use decisions. The long-term goals of the comprehensive integrated planning process, in priority order, are to support DOE critical missions and to stimulate the economy while maintaining a quality environment.

  16. The feedback-related negativity is modulated by feedback probability in observational learning.

    PubMed

    Kobza, Stefan; Thoma, Patrizia; Daum, Irene; Bellebaum, Christian

    2011-12-01

    The feedback-related negativity (FRN), an event-related potentials (ERPs) component reflecting activity of the anterior cingulate cortex (ACC), has been shown to be modulated by feedback expectancy following active choices in feedback-based learning tasks. A general reduction of FRN amplitude has been described in observational feedback learning, raising the question whether FRN amplitude is modulated in a similar way in this type of learning. The present study investigated whether the FRN and the P300 - a second ERP component related to feedback processing - are modulated by feedback probability in observational learning. Thirty-two subjects participated in the experiment. They observed a virtual person choosing between two symbols and receiving positive or negative feedback. Learning about stimulus-specific feedback probabilities was assessed in active test trials without feedback. In addition, the bias to learn from positive or negative feedback and - in a subsample of 17 subjects - empathy scores were obtained. General FRN and P300 modulations by feedback probability were found across all subjects. Only for the FRN in learners, an interaction between probability and valence was observed. Larger FRN amplitudes for negative relative to positive feedback only emerged for the lowest outcome probability. The results show that feedback expectancy modulates FRN amplitude also in observational learning, suggesting a similar ACC function as in active learning. On the other hand, the modulation is only seen for very low feedback expectancy, which suggests that brain regions other than those of the reward system contribute to feedback processing in an observation setting.

  17. An analysis of ridge axis gravity roughness and spreading rate

    NASA Technical Reports Server (NTRS)

    Small, Christopher; Sandwell, David T.

    1992-01-01

    Fast and slow spreading ridges have radically different morphologic and gravimetric characteristics. In this study, altimeter measurements from the Geosat Exact Repeat Mission are used to investigate spreading rate dependence of the ridge axis gravity field. Gravity roughness provides an estimate of the amplitude of the gravity anomaly and is robust to small errors in the location of the ridge axis. Gravity roughness as a weighted root mean square of the vertical deflection at 438 ridge crossings on the mid-ocean ridge system is computed. Ridge axis gravity anomalies show a decrease in amplitude with increasing spreading rate up to an intermediate rate of about 60-80 mm/yr and almost no change at higher rates; overall the roughness decreases by a factor of 10 between the lowest and highest rates. In addition to the amplitude decrease, the range of roughness values observed at a given spreading rate shows a similar order of magnitude decrease with transition between 60 and 80 mm/yr. The transition of ridge axis gravity is most apparent at three relatively unexplored locations on the Southeast Indian Ridge and the Pacific-Antarctic Rise; on these intermediate rate ridges the transition occurs abruptly across transform faults.

  18. Mantle plume capture, anchoring and outflow during ridge interaction

    NASA Astrophysics Data System (ADS)

    Gibson, S. A.; Richards, M. A.; Geist, D.

    2015-12-01

    Geochemical and geophysical studies have shown that >40% of the world's mantle plumes are currently interacting with the global ridge system and such interactions may continue for up to 180 Myr[1]. At sites of plume-ridge interaction up to 1400 km of the spreading centre is influenced by dispersed plume material but there are few constraints on how and where the ridge-ward transfer of deep-sourced material occurs, and also how it is sustained over long time intervals. Galápagos is an archetypal example of an off-axis plume and sheds important light on these mechanisms. The Galápagos plume stem is located ~200 km south of the spreading axis and its head influences 1000 km of the ridge. Nevertheless, the site of enriched basalts, greatest crustal thickness and elevated topography on the ridge, together with active volcanism in the archipelago, correlate with a narrow zone (~150 km) of low-velocity, high-temperature mantle that connects the plume stem and ridge at depths of ~100 km[2]. The enriched ridge basalts contain a greater amount of partially-dehydrated, recycled oceanic crust than basalts elsewhere on the spreading axis, or indeed basalts erupted in the region between the plume stem and ridge. The presence of these relatively volatile-rich ridge basalts requires flow of plume material below the peridotite solidus (i.e.>80 km). We propose a 2-stage model for the development and sustainment of a confined zone of deep ridge-ward plume flow. This involves initial on-axis capture and establishment of a sub-ridge channel of plume flow. Subsequent anchoring of the plume stem to a contact point on the ridge during axis migration results in confined ridge-ward flow of plume material via a deep network of melt channels embedded in the normal spreading and advection of the plume head[2]. Importantly, sub-ridge flow is maintained. The physical parameters and styles of mantle flow we have defined for Galápagos are less-well known at other sites of plume-ridge

  19. Custom Titanium Ridge Augmentation Matrix (CTRAM): A Case Report.

    PubMed

    Connors, Christopher A; Liacouras, Peter C; Grant, Gerald T

    2016-01-01

    This is a case report of a custom titanium ridge augmentation matrix (CTRAM). Using cone beam computed tomography (CBCT), a custom titanium space-maintaining device was developed. Alveolar ridges were virtually augmented, a matrix was virtually designed, and the CTRAM was additively manufactured with titanium (Ti6Al4V). Two cases are presented that resulted in sufficient increased horizontal bone volume with successful dental implant placement. The CTRAM design allows for preoperative planning for increasing alveolar ridge dimensions to support dental implants, reduces surgical time, and prevents the need for a second surgical site to gain sufficient alveolar ridge bone volume for dental implant therapy. PMID:27560675

  20. From tides to mixing along the Hawaiian ridge.

    PubMed

    Rudnick, Daniel L; Boyd, Timothy J; Brainard, Russell E; Carter, Glenn S; Egbert, Gary D; Gregg, Michael C; Holloway, Peter E; Klymak, Jody M; Kunze, Eric; Lee, Craig M; Levine, Murray D; Luther, Douglas S; Martin, Joseph P; Merrifield, Mark A; Moum, James N; Nash, Jonathan D; Pinkel, Robert; Rainville, Luc; Sanford, Thomas B

    2003-07-18

    The cascade from tides to turbulence has been hypothesized to serve as a major energy pathway for ocean mixing. We investigated this cascade along the Hawaiian Ridge using observations and numerical models. A divergence of internal tidal energy flux observed at the ridge agrees with the predictions of internal tide models. Large internal tidal waves with peak-to-peak amplitudes of up to 300 meters occur on the ridge. Internal-wave energy is enhanced, and turbulent dissipation in the region near the ridge is 10 times larger than open-ocean values. Given these major elements in the tides-to-turbulence cascade, an energy budget approaches closure.

  1. Ridges and scarps in the equatorial belt of Mars

    USGS Publications Warehouse

    Lucchitta, B.K.; Klockenbrink, J.L.

    1981-01-01

    The morphology and distribution of ridges and scarps on Mars in the ?? 30?? latitude belt were investigated. Two distinct types of ridges were recognized. The first is long and linear, resembling mare ridges on the Moon; it occurs mostly in plains areas. The other is composed of short, anastomosing segments and occurs mostly in ancient cratered terrain and intervening plateaus. Where ridges are eroded, landscape configurations suggest that they are located along regional structures. The age of ridges is uncertain, but some are as young as the latest documented volcanic activity on Mars. The origins of ridges are probably diverse-they may result from wrinkling due to compression or from buckling due to settling over subsurface structures. The similar morphologic expressions of ridge types of various origins may be related to a similar deformation mechanism caused by two main factors: (1) most ridges are developed in thick layers of competent material and (2) ridges formed under stresses near a free surface. ?? 1981 D. Reidel Publishing Co.

  2. From tides to mixing along the Hawaiian ridge.

    PubMed

    Rudnick, Daniel L; Boyd, Timothy J; Brainard, Russell E; Carter, Glenn S; Egbert, Gary D; Gregg, Michael C; Holloway, Peter E; Klymak, Jody M; Kunze, Eric; Lee, Craig M; Levine, Murray D; Luther, Douglas S; Martin, Joseph P; Merrifield, Mark A; Moum, James N; Nash, Jonathan D; Pinkel, Robert; Rainville, Luc; Sanford, Thomas B

    2003-07-18

    The cascade from tides to turbulence has been hypothesized to serve as a major energy pathway for ocean mixing. We investigated this cascade along the Hawaiian Ridge using observations and numerical models. A divergence of internal tidal energy flux observed at the ridge agrees with the predictions of internal tide models. Large internal tidal waves with peak-to-peak amplitudes of up to 300 meters occur on the ridge. Internal-wave energy is enhanced, and turbulent dissipation in the region near the ridge is 10 times larger than open-ocean values. Given these major elements in the tides-to-turbulence cascade, an energy budget approaches closure. PMID:12869758

  3. Ridge Orientations of the Ridge-Forming Unit, Sinus Meridiani, Mars-A Fluvial Explanation

    NASA Technical Reports Server (NTRS)

    Wilkinson, M. Justin; Herridge, A.

    2013-01-01

    Imagery and MOLA data were used in an analysis of the ridge-forming rock unit (RFU) exposed in Sinus Meridiani (SM). This unit shows parallels at different scales with fluvial sedimentary bodies. We propose the terrestrial megafan as the prime analog for the RFU, and likely for other members of the layered units. Megafans are partial cones of fluvial sediment, with radii up to hundreds of km. Although recent reviews of hypotheses for the RFU units exclude fluvial hypotheses [1], inverted ridges in the deserts of Oman have been suggested as putative analogs for some ridges [2], apparently without appreciating The wider context in which these ridges have formed is a series of megafans [3], a relatively unappreciated geomorphic feature. It has been argued that these units conform to the megafan model at the regional, subregional and local scales [4]. At the regional scale suites of terrestrial megafans are known to cover large areas at the foot of uplands on all continents - a close parallel with the setting of the Meridiani sediments at the foot of the southern uplands of Mars, with its incised fluvial systems leading down the regional NW slope [2, 3] towards the sedimentary units. At the subregional scale the layering and internal discontinuities of the Meridiani rocks are consistent, inter alia, with stacked fluvial units [4]. Although poorly recognized as such, the prime geomorphic environment in which stream channel networks cover large areas, without intervening hillslopes, is the megafan [see e.g. 4]. Single megafans can reach 200,000 km2 [5]. Megafans thus supply an analog for areas where channel-like ridges (as a palimpsest of a prior landscape) cover the intercrater plains of Meridiani [6]. At the local, or river-reach scale, the numerous sinuous features of the RFU are suggestive of fluvial channels. Cross-cutting relationships, a common feature of channels on terrestrial megafans, are ubiquitous. Desert megafans show cemented paleo-channels as inverted

  4. US Department of Energy Oak Ridge Operations Environmental Management Public Involvement Plan for the Oak Ridge Reservation

    SciTech Connect

    1996-03-01

    This document was prepared in accordance with CERCLA requirements for writing community relations plans. It includes information on how the DOE Oak Ridge Operations Office prepares and executes Environmental Management Community relations activities. It is divided into three sections: the public involvement plan, public involvement in Oak Ridge, and public involvement in 1995. Four appendices are also included: environmental management in Oak Ridge; community and regional overview; key laws, agreements, and policy; and principal contacts.

  5. Comparison of buried sand ridges and regressive sand ridges on the outer shelf of the East China Sea

    NASA Astrophysics Data System (ADS)

    Wu, Ziyin; Jin, Xianglong; Zhou, Jieqiong; Zhao, Dineng; Shang, Jihong; Li, Shoujun; Cao, Zhenyi; Liang, Yuyang

    2016-07-01

    Based on multi-beam echo soundings and high-resolution single-channel seismic profiles, linear sand ridges in U14 and U2 on the East China Sea (ECS) shelf are identified and compared in detail. Linear sand ridges in U14 are buried sand ridges, which are 90 m below the seafloor. It is presumed that these buried sand ridges belong to the transgressive systems tract (TST) formed 320-200 ka ago and that their top interface is the maximal flooding surface (MFS). Linear sand ridges in U2 are regressive sand ridges. It is presumed that these buried sand ridges belong to the TST of the last glacial maximum (LGM) and that their top interface is the MFS of the LGM. Four sub-stage sand ridges of U2 are discerned from the high-resolution single-channel seismic profile and four strikes of regressive sand ridges are distinguished from the submarine topographic map based on the multi-beam echo soundings. These multi-stage and multi-strike linear sand ridges are the response of, and evidence for, the evolution of submarine topography with respect to sea-level fluctuations since the LGM. Although the difference in the age of formation between U14 and U2 is 200 ka and their sequences are 90 m apart, the general strikes of the sand ridges are similar. This indicates that the basic configuration of tidal waves on the ECS shelf has been stable for the last 200 ka. A basic evolutionary model of the strata of the ECS shelf is proposed, in which sea-level change is the controlling factor. During the sea-level change of about 100 ka, five to six strata are developed and the sand ridges develop in the TST. A similar story of the evolution of paleo-topography on the ECS shelf has been repeated during the last 300 ka.

  6. [Comparative study of N, P output and eutrophication risk in runoff water in cross ridge and longitudinal ridge].

    PubMed

    Yu, Xing-Xiu; Ma, Qian; Liu, Qian-Jin; Lü, Guo-An

    2011-02-01

    Field in-situ rainfall simulation tests with two rainfall intensities (40 mm x h(-1) and 70 mm x h(-1)), which were conducted at typical sloping cropland in Yimeng mountainous area, were designed to analyze the output characteristics of dissolved inorganic nitrogen, Inorganic-N (NO3(-)-N, NH4(+) -N) and dissolved phosphorus (DP) in runoff water, as well as to compare the eutrophication risk in this water by calculating three ratios of Inorganic-N/DP, NO3(-) -N/DP, and NH4(+)-N/DP, respectively, in cross ridge and longitudinal ridge tillage methods. Results showed that, under the same rainfall intensity, the DP level in runoff water was higher in cross ridge than longitudinal ridge, while the change of different Inorganic-N level between the two tillage methods were not consistent. Cross ridge could effectively reduce runoff and the output rate of Inorganic-N and DP when compared to the longitudinal ridge tillage, which would be more outstanding with the increases of rainfall intensities. The losses of Inorganic-N and DP in runoff water were 43% and 5% less, respectively, in cross ridge than longitudinal ridge at the 40 mm x h(-1) rainfall intensity, and were 68% and 55%, respectively, at 70 mm x h(-1). The higher Inorganic-N/DP and NO3(-) -N/DP ratios suggest that runoff water from either cross ridge or longitudinal ridge tillage have a certain eutrophication risk, which present an increasing trend during the precipitation-runoff process. Compared with longitudinal ridge, cross ridge can not only hinder the increasing trend of eutrophication risk, but also can significantly lower it, and thus effectively reduce the effect of sloping cropland runoff on the eutrophication processes of receiving waters.

  7. Topographic amplification across a taiwanese ridge

    NASA Astrophysics Data System (ADS)

    Rault, Claire; Meunier, Patrick; Burtin, Arnaud; Marc, Odin; Weian Chao, Vvn; Wu, Yih-Min; Hovius, Niels

    2016-04-01

    A line of 6 broadband seismometers have been deployed across a ridge in the Hualien County (Eastern Taiwan) in order to study topographic amplification. Since March 2015, the network has been continuously recording waves incoming from the Taiwanese regional seismicity. The hill is well approximated by a triangular topography of 3600m in length by 900m in height. We present a preliminary analysis performed over a dozen of earthquakes selected from the Seismic Taiwanese catalog (CWBSN). We show that most of the Uphill records exhibit a systematic amplification of seismic waves (peak to peak of particle velocity) in the relevant frequency band [0.5-2Hz]. By contrast, energy within the larger frequency band [6-20Hz] reflects local site effects induced by the soil layer. We report amplification ratios ranging from ranging from 1.2 to 3 and from 1.8 to 4 for P and S waves respectively. We show that amplification processes at the top strongly depend on the parameter α defined as the angle between the azimuth of incoming wave and the azimuth of the ridge divide.

  8. VERITAS Observations of The Galactic Center Ridge

    NASA Astrophysics Data System (ADS)

    Smith, Andrew W

    2014-08-01

    The Galactic Center Ridge is perhaps the most local, busy environment for high-energy particle acceleration, harboring as it does many relativistic particle accelerators such as pulsar wind nebulae, supernova remnants, and the central supermassive black hole SgrA*. Observations with very high energy (VHE, >100 GeV) gamma-ray telescopes of the region have revealed multiple point sources associated with well-known objects, as well as regions of extended emission not directly associated with sources at other wavelengths. More importantly, the detection of a large, diffuse component of >300 GeV gamma-ray emission by the HESS collaboration is strongly believed to be the result of accelerated cosmic rays interacting with molecular-cloud regions, thus providing insight into high-energy cosmic ray acceleration. Here we present the VERITAS observations of the Galactic Center Ridge taken from 2008-2014 in the >2 TeV regime. We will focus on the VERITAS results on the known HESS sources in the region, as well as the diffuse component of TeV emission along the plane. Due to the much higher energy threshold of the VERITAS observations, our data provide a new window into some of the highest energy particle acceleration occurring in the center of our galaxy.

  9. VERITAS Observations of The Galactic Center Ridge

    NASA Astrophysics Data System (ADS)

    Smith, Andrew; Veritas

    2015-01-01

    The Galactic Center Ridge is perhaps the most local, busy environment for high energy particle acceleration; home to many relativistic particle accelerators such as pulsar wind nebulae, supernova remnants, and the central supermassive black hole SgrA*. Observations with VHE (>100 GeV) gamma-ray telescopes of the region have revealed multiple point sources associated with well known objects, as well as regions of extended emission not directly associated with targets at other wavelengths. More importantly, the detection of a large, diffuse component of >300 GeV gamma-ray emission by the HESS collaboration is strongly believed to be the result of accelerated cosmic rays interacting with molecular cloud regions, thus providing a window into high energy cosmic ray acceleration. Here we present the VERITAS observations of the Galactic Center Ridge taken from 2008-2014 in the >2 TeV regime. We will focus on the VERITAS results on the known HESS sources in the region, as well as the diffuse component of TeV emission along the plane. Due to the much higher energy threshold of the VERITAS observations, our data provide a new window into some of the highest energy particle acceleration occurring in the center of our galaxy.

  10. The Oak Ridge Isochronous Cyclotron Refurbishment Project

    SciTech Connect

    Mendez, II, Anthony J; Ball, James B; Dowling, Darryl T; Mosko, Sigmund W; Tatum, B Alan

    2011-01-01

    The Oak Ridge Isochronous Cyclotron (ORIC) has been in operation for nearly fifty years at the Oak Ridge National Laboratory (ORNL). Presently, it serves as the driver accelerator for the ORNL Holifield Radioactive Ion Beam Facility (HRIBF), where radioactive ion beams are produced using the Isotope Separation Online (ISOL) technique for post-acceleration by the 25URC tandem electrostatic accelerator. Operability and reliability of ORIC are critical issues for the success of HRIBF and have presented increasingly difficult operational challenges for the facility in recent years. In February 2010, a trim coil failure rendered ORIC inoperable for several months. This presented HRIBF with the opportunity to undertake various repairs and maintenance upgrades aimed at restoring the full functionality of ORIC and improving the reliability to a level better than what had been typical over the previous decade. In this paper, we present details of these efforts, including the replacement of the entire trim coil set and measurements of their radial field profile. Comparison of measurements and operating tune parameters with setup code predictions will also be presented.

  11. Multiple-Try Feedback and Higher-Order Learning Outcomes

    ERIC Educational Resources Information Center

    Clariana, Roy B.; Koul, Ravinder

    2005-01-01

    Although feedback is an important component of computer-based instruction (CBI), the effects of feedback on higher-order learning outcomes are not well understood. Several meta-analyses provide two rules of thumb: any feedback is better than no feedback and feedback with more information is better than feedback with less information. …

  12. Improved Digitization of Lunar Mare Ridges with LROC Derived Products

    NASA Astrophysics Data System (ADS)

    Crowell, J. M.; Robinson, M. S.; Watters, T. R.; Bowman-Cisneros, E.; Enns, A. C.; Lawrence, S.

    2011-12-01

    Lunar wrinkle ridges (mare ridges) are positive-relief structures formed from compressional stress in basin-filling flood basalt deposits [1]. Previous workers have measured wrinkle ridge orientations and lengths to investigate their spatial distribution and infer basin-localized stress fields [2,3]. Although these plots include the most prominent mare ridges and their general trends, they may not have fully captured all of the ridges, particularly the smaller-scale ridges. Using Lunar Reconnaissance Orbiter Wide Angle Camera (WAC) global mosaics and derived topography (100m pixel scale) [4], we systematically remapped wrinkle ridges in Mare Serenitatis. By comparing two WAC mosaics with different lighting geometry, and shaded relief maps made from a WAC digital elevation model (DEM) [5], we observed that some ridge segments and some smaller ridges are not visible in previous structure maps [2,3]. In the past, mapping efforts were limited by a fixed Sun direction [6,7]. For systematic mapping we created three shaded relief maps from the WAC DEM with solar azimuth angles of 0°, 45°, and 90°, and a fourth map was created by combining the three shaded reliefs into one, using a simple averaging scheme. Along with the original WAC mosaic and the WAC DEM, these four datasets were imported into ArcGIS, and the mare ridges of Imbrium, Serenitatis, and Tranquillitatis were digitized from each of the six maps. Since the mare ridges are often divided into many ridge segments [8], each major component was digitized separately, as opposed to the ridge as a whole. This strategy enhanced our ability to analyze the lengths, orientations, and abundances of these ridges. After the initial mapping was completed, the six products were viewed together to identify and resolve discrepancies in order to produce a final wrinkle ridge map. Comparing this new mare ridge map with past lunar tectonic maps, we found that many mare ridges were not recorded in the previous works. It was noted

  13. Feedbacks Between Topographic Stress and Drainage Basin Evolution

    NASA Astrophysics Data System (ADS)

    Perron, J.; Martel, S. J.; Singha, K.; Slim, M. I.

    2013-12-01

    Theoretical calculations imply that stresses produced by gravity acting on topography may be large enough in some scenarios to fracture rock. Predicted stress fields beneath ridges and valleys can differ dramatically, which has led several authors to hypothesize feedbacks between topographic stress, rock fracture and landscape evolution. However, there have been few attempts to explore these feedbacks. We use a coupled model to identify possible feedbacks between topographic stress and drainage basin evolution. The domain is a cross-section of a valley consisting of a bedrock channel and adjacent soil-mantled hillslopes. The bedrock surface evolves due to channel incision, soil production, and rock uplift, and soil thickness evolves due to soil production and transport. Plane stresses at and below the bedrock surface are calculated with a boundary element method that accounts for both ambient tectonic stress and topographic stress. We assume that the stress field experienced by rock as it is exhumed influences the likelihood that it will develop fractures, which make the rock more susceptible to weathering, disaggregation and erosion. A measure of susceptibility to shear fracture, the most likely failure mode under regional compression, serves as a proxy for rock damage. We couple the landscape evolution model to the stress model by assuming that rock damage accelerates the rates of soil production and channel incision, with two endmember cases: rates scale with the magnitude of the damage proxy at the bedrock surface, or with cumulative damage acquired during rock exhumation. The stress-induced variations in soil production and channel incision alter the soil thickness and topography, which in turn alter the stress field. Comparing model simulations with and without these feedbacks, we note several predicted consequences of topographic stress for drainage basin evolution. Rock damage is typically focused at or near the foot of hillslopes, which creates thicker

  14. Feedback enhanced plasma spray tool

    DOEpatents

    Gevelber, Michael Alan; Wroblewski, Donald Edward; Fincke, James Russell; Swank, William David; Haggard, Delon C.; Bewley, Randy Lee

    2005-11-22

    An improved automatic feedback control scheme enhances plasma spraying of powdered material through reduction of process variability and providing better ability to engineer coating structure. The present inventors discovered that controlling centroid position of the spatial distribution along with other output parameters, such as particle temperature, particle velocity, and molten mass flux rate, vastly increases control over the sprayed coating structure, including vertical and horizontal cracks, voids, and porosity. It also allows improved control over graded layers or compositionally varying layers of material, reduces variations, including variation in coating thickness, and allows increasing deposition rate. Various measurement and system control schemes are provided.

  15. Visual feedback in stuttering therapy

    NASA Astrophysics Data System (ADS)

    Smolka, Elzbieta

    1997-02-01

    The aim of this paper is to present the results concerning the influence of visual echo and reverberation on the speech process of stutterers. Visual stimuli along with the influence of acoustic and visual-acoustic stimuli have been compared. Following this the methods of implementing visual feedback with the aid of electroluminescent diodes directed by speech signals have been presented. The concept of a computerized visual echo based on the acoustic recognition of Polish syllabic vowels has been also presented. All the research nd trials carried out at our center, aside from cognitive aims, generally aim at the development of new speech correctors to be utilized in stuttering therapy.

  16. Auditory categories with separable decision boundaries are learned faster with full feedback than with minimal feedback.

    PubMed

    Yi, Han Gyol; Chandrasekaran, Bharath

    2016-08-01

    During visual category learning, full feedback (e.g., "Wrong, that was a category 4."), relative to minimal feedback (e.g., "Wrong."), enhances performance when the relevant dimensions are separable. This pattern is reversed with inseparable dimensions. Here, the interaction between trial-by-trial feedback and separability of dimensions in the auditory domain is examined. Participants were trained to categorize auditory stimuli along separable or inseparable dimensions. One group received full feedback, while the other group received minimal feedback. In the separable-dimensions condition, the full-feedback group achieved higher accuracy than did the minimal-feedback group. In the inseparable-dimensions condition, performance was equivalent across the feedback groups. These results altogether suggest that trial-by-trial feedback affects auditory category learning performance differentially for separable and inseparable categories. PMID:27586759

  17. Coupled ice shelf-ocean modeling and complex grounding line retreat from a seabed ridge

    NASA Astrophysics Data System (ADS)

    De Rydt, J.; Gudmundsson, G. H.

    2016-05-01

    Recent observations and modeling work have shown a complex mechanical coupling between Antarctica's floating ice shelves and the adjacent grounded ice sheet. A prime example is Pine Island Glacier, West Antarctica, which has a strong negative mass balance caused by a recent increase in ocean-induced melting of its ice shelf. The mass loss coincides with the retreat of the grounding line from a seabed ridge, on which it was at least partly grounded until the 1970s. At present, it is unclear what has caused the onset of this retreat and how feedback mechanisms between the ocean and ice shelf geometry have influenced the ice dynamics. To address these questions, we present the first results from an offline coupling between a state-of-the-art shallow-ice flow model with grounding line resolving capabilities and a three-dimensional ocean general circulation model with a static implementation of the ice shelf. A series of idealized experiments simulate the retreat from a seabed ridge in response to changes in the ocean forcing, and we show that the retreat becomes irreversible after 20 years of warm ocean conditions. A comparison to experiments with a simple depth-dependent melt rate parameterization demonstrates that such parameterizations are unable to capture the details of the retreat process, and they overestimate mass loss by more than 40% over a 50 year timescale.

  18. DESIGN AND ANALYSIS OF AN FPGA-BASED ACTIVE FEEDBACK DAMPING SYSTEM

    SciTech Connect

    Xie, Zaipeng; Schulte, Mike; Deibele, Craig Edmond

    2010-01-01

    The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory is a high-intensity proton-based accelerator that produces neutron beams for neutronscattering research. As the most powerful pulsed neutron source in the world, the SNS accelerator has experienced an unprecedented beam instability that has a wide bandwidth (0 to 300MHz) and fast growth time (10 to100 s). In this paper, we propose and analyze several FPGA-based designs for an active feedback damping system. This signal processing system is the first FPGA-based design for active feedback damping of wideband instabilities in high intensity accelerators. It can effectively mitigate instabilities in highintensity protons beams, reduce radiation, and boost the accelerator s luminosity performance. Unlike existing systems, which are designed using analog components, our FPGA-based active feedback damping system offers programmability while maintaining high performance. To meet the system throughput and latency requirements, our proposed designs are guided by detailed analysis of resource and performance tradeoffs. These designs are mapped onto a reconfigurable platform that includes Xilinx Virtex-II Pro FPGAs and high-speed analog-to-digital and digital-toanalog converters. Our results show that our FPGA-based active feedback damping system can provide increased flexibility and improved signal processing performance that are not feasible with existing analog systems.

  19. How vegetation and sediment transport feedbacks drive landscape change in the everglades and wetlands worldwide.

    PubMed

    Larsen, Laurel G; Harvey, Judson W

    2010-09-01

    Mechanisms reported to promote landscape self-organization cannot explain vegetation patterning oriented parallel to flow. Recent catastrophic shifts in Everglades landscape pattern and ecological function highlight the need to understand the feedbacks governing these ecosystems. We modeled feedback between vegetation, hydrology, and sediment transport on the basis of a decade of experimentation. Results from more than 100 simulations showed that flows just sufficient to redistribute sediment from sparsely vegetated sloughs to dense ridges were needed for an equilibrium patterned landscape oriented parallel to flow. Surprisingly, although vegetation heterogeneity typically conveys resilience, in wetlands governed by flow/sediment feedbacks it indicates metastability, whereby the landscape is prone to catastrophic shifts. Substantial increases or decreases in flow relative to the equilibrium condition caused an expansion of emergent vegetation and loss of open-water areas that was unlikely to revert upon restoration of the equilibrium hydrology. Understanding these feedbacks is critical in forecasting wetland responses to changing conditions and designing management strategies that optimize ecosystem services, such as carbon sequestration or habitat provision. Our model and new sensitivity analysis techniques address these issues and make it newly apparent that simply returning flow to predrainage conditions in the Everglades may not be sufficient to restore historic landscape patterns and processes.

  20. Closed-loop, non-linear feedback control simulations of beam-driven field-reversed configurations (FRCs)

    NASA Astrophysics Data System (ADS)

    Rath, N.; Onofri, M.; Barnes, D.; Romero, J.; the TAE Team

    2015-11-01

    The C-2U device has recently demonstrated sustainment of an advanced, beam-driven FRC over time scales longer than the characteristic times for confinement, fast ion slow-down, and wall current decay. In anticipation of further advances in plasma lifetime, we are developing feedback control techniques for major FRC parameters and resistive instabilities. The LamyRidge code solves the time-dependent extended MHD equations in axisymmetric geometry. In the Q2D code, LamyRidge is combined with a 3-D kinetic code that tracks fast ions and runs in parallel with LamyRidge. Periodically, the background fields in the kinetic code are updated from the MHD simulation and the averaged fast particle distribution is integrated into the fluid equations. Recently, we have added the capability to run Q2D simulations as subordinate processes in Simulink, giving us the ability to run non-linear, closed-loop simulations using control algorithms developed in Simulink. The same Simulink models can be exported to real-time targets (CPU or FPGA) to perform feedback control in experiments. We present closed-loop simulations of beam-driven FRCs under magnetically-actuated feedback control. Results for positionally unstable FRCs are compared with the predictions of a linearized rigid-plasma model. Plasmas predicted to be passively stabilized by the linear model are found to exhibit Alfvenic growth in several cases. Feedback gains predicted to be stabilizing in the linear model are generally found to be insufficient in non-linear simulations, and vice versa. Control of separatrix geometry is demonstrated.

  1. RF power recovery feedback circulator

    DOEpatents

    Sharamentov, Sergey I.

    2011-03-29

    A device and method for improving the efficiency of RF systems having a Reflective Load. In the preferred embodiment, Reflected Energy from a superconducting resonator of a particle accelerator is reintroduced to the resonator after the phase of the Reflected Energy is aligned with the phase of the Supply Energy from a RF Energy Source. In one embodiment, a Circulator is used to transfer Reflected Energy from the Reflective Load into a Phase Adjuster which aligns the phase of the Reflected Energy with that of the Supply Energy. The phase-aligned energy is then combined with the Supply Energy, and reintroduced into the Reflective Load. In systems having a constant phase shift, the Phase Adjuster may be designed to shift the phase of the Reflected Energy by a constant amount using a Phase Shifter. In systems having a variety (variable) phase shifts, a Phase Shifter controlled by a phase feedback loop comprising a Phase Detector and a Feedback Controller to account for the various phase shifts is preferable.

  2. Alkalic Basalt in Ridge Axis of 53˚E Amagmatic Segment Center, Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Zhou, H.; Wang, J.; Liu, Y.; Ji, F.; Dick, H. J.

    2014-12-01

    Mid-ocean ridge basalt (MORB) is key tracer of composition and process in the mantle. It is interesting to notice that some alkalic basalts occur in amagmatic spreading center of ultraslow spreading ridges, for examples, 9-16˚E of the Southwest Indian ridge (Standish et al., 2008) and Lena Trough of Arctic Ocean (Snow et al., 2011). The latter is interpreted as the result of the pre-existence of continental transform fault or the especially cold thermal structure of ancient continental lithosphere. 53˚E segment, east of the Gallieni transform fault, was discovered as an amagmatic segment (Zhou and Dick, 2013). On both sides of the ridge axis, peridotites with a little gabbro are exposed in an area more than 3200 km2. Basalts exist in the southern portion of 53˚E segment, indicating the transformation from magmatic to amagmatic spreading about 9.4 million years ago. In April of 2014, Leg 4 of the RV Dayang Yihao cruise 30, basaltic glasses was dredged at one location (3500 m water depth) in the ridge axis of 53˚E segment center. It is shown by electric probe analysis that the samples have extremely high sodium content (4.0-4.49 wt% Na­2O ), relative higher potassium content (0.27-0.32 wt% K2O) and silica (50.67-51.87 wt% SiO2), and lower MgO content (5.9-6.4 wt% MgO). Mg-number is 0.55-0.59. It is distinctly different from the N-MORB (2.42-2.68 wt% Na2O, 0.03-0.06 wt% K2O, 48.6-49.6 wt% Si2O, 8.8-9.0 wt% MgO, Mg-numbers 0.63) distributed in the 560-km-long supersegment, west of the Gallieni transform fault, where the active Dragon Flag hydrothermal field was discovered at 49.6˚E in 2007. The reasons for the alkalic basalt in the ridge axis of 53˚E amagmatic segment center, either by low melting degree of garnet stability field, by melting from an ancient subcontinental lithospheric mantle, or by sodium-metasomatism or even other mantle processes or their combination in the deep mantle, are under further studies.

  3. 60 Years of Great Science (Oak Ridge National Laboratory)

    DOE R&D Accomplishments Database

    2003-01-01

    This issue of Oak Ridge National Laboratory Review (vol. 36, issue 1) highlights Oak Ridge National Laboratory's contributions in more than 30 areas of research and related activities during the past 60 years and provides glimpses of current activities that are carrying on this heritage.

  4. Dielectrophoresis device and method having insulating ridges for manipulating particles

    SciTech Connect

    Cummings, Eric B.; Fiechtner, Gregory J.

    2008-03-25

    Embodiments of the present invention provide methods and devices for manipulating particles using dielectrophoresis. Insulating ridges and valleys are used to generate a spatially non-uniform electrical field. Particles may be concentrated, separated, or captured during bulk fluid flow in a channel having insulating ridges and valleys.

  5. Mantle anisotropy beneath the Earth's mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Nowacki, Andy; Kendall, J.-Michael; Wookey, James

    2012-02-01

    Observations of seismic anisotropy at oceanic spreading centres offer insights into mid-ocean ridge processes and the formation of new plates. Here, remote observations of seismic anisotropy beneath mid-ocean ridges are made using measurements of source-side shear wave splitting. Over 100 high-quality measurements are made using earthquakes that occur near mid-ocean ridges and transform faults, but are observed at teleseismic distances. In general, for off-axis ridge events, the polarisation of fast shear waves, ϕ″, is approximately parallel to the spreading direction. Nearer the ridge (<~50 km), ϕ″ becomes more scattered and is often ridge-parallel. Delay times, δt, tend to increase from < 1 s near the ridge axis to ˜ 3 s further away. Slow-spreading regions (Gakkel and Southwest Indian Ridges) show smaller amounts of splitting than faster spreading centres. At transform zones, the pattern is more complex. Coverage beneath the East Pacific Rise is especially good, and we observe a systematic increase in delay times in S wave splitting measurements compared to previous SKS splitting observations made at ocean-bottom seismometers. One compatible explanation is the presence of horizontally-aligned, connected layers of melt at depth; this is also compatible with other observations of the 'LAB' discontinuity and surface-wave derived measurements of radial anisotropy.

  6. 203. Lickstone Ridge Tunnel. All but three of the tunnel ...

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

    203. Lickstone Ridge Tunnel. All but three of the tunnel have minimum height of 13, which accommodates most large recreational vehicles. This tunnel has the lowest clearance at 11-3. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  7. Site characterization of the West Chestnut Ridge site

    SciTech Connect

    Ketelle, R H; Huff, D D

    1984-09-01

    This report summarizes the results of investigations performed to date on the West Chestnut Ridge Site, on the Department of Energy (DOE) Oak Ridge Reservation. The investigations performed include geomorphic observations, areal geologic mapping, surficial soil mapping, subsurface investigations, soil geochemical and mineralogical analyses, geohydrologic testing, groundwater fluctuation monitoring, and surface water discharge and precipitation monitoring. 33 references, 32 figures, 24 tables.

  8. 2. Building 7 west elevation oblique from Ridge Avenue, showing ...

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

    2. Building 7 west elevation oblique from Ridge Avenue, showing entrance to complex between Building 7 (right) and Building 8 (left). View looking NE. - John & James Dobson Carpet Mill (West Parcel), Building No. 7, 4041-4055 Ridge Avenue, Philadelphia, Philadelphia County, PA

  9. 2. General view from Richmond Branch Reading RR across Ridge ...

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

    2. General view from Richmond Branch Reading RR across Ridge Avenue from Dobson Mills complex, showing entrance (between Buildings 8 on left and 7 on right), looking NE. Building 13/14 clearly visible in background to left. - John & James Dobson Carpet Mill (West Parcel), 4041-4055 Ridge Avenue, Philadelphia, Philadelphia County, PA

  10. Validity Shrinkage in Ridge Regression: A Simulation Study.

    ERIC Educational Resources Information Center

    Faden, Vivian; Bobko, Philip

    1982-01-01

    Ridge regression offers advantages over ordinary least squares estimation when a validity shrinkage criterion is considered. Comparisons of cross-validated multiple correlations indicate that ridge estimation is superior when the predictors are multicollinear, the number of predictors is large relative to sample size, and the population multiple…

  11. View of middle portion of Bonita Ridge Access Road Retaining ...

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

    View of middle portion of Bonita Ridge Access Road Retaining Wall, showing Signal Corps Radar 296 Station 5 Tower concrete pier (top center), camera facing northwest - Fort Barry, Bonita Ridge Access Road, Retaining Wall, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

  12. Oblique view of Bonita Ridge Access Road Retaining Wall, showing ...

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

    Oblique view of Bonita Ridge Access Road Retaining Wall, showing southernmost portion of intact wall and portion of concrete drainage ditch from Signal Corps Radar 296 Station 5 Transmitter Building foundation above, camera facing west-north - Fort Barry, Bonita Ridge Access Road, Retaining Wall, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

  13. Contextual view of Bonita Ridge Access Road Retaining Wall, showing ...

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

    Contextual view of Bonita Ridge Access Road Retaining Wall, showing concrete stairway and ramp with Army Fire Control Station (Buildings 621 and 622) at far left, camera facing southwest - Fort Barry, Bonita Ridge Access Road, Retaining Wall, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

  14. 1. AERIAL VIEW, LOOKING SOUTHWEST, ALONG THE RIDGE WITH RESIDENTIAL ...

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

    1. AERIAL VIEW, LOOKING SOUTHWEST, ALONG THE RIDGE WITH RESIDENTIAL DISTRICTS EXTENDING EAST TO THE RADIO TOWERS AT U.S. 31 (TOP RIGHT), SHADES VALLEY (TO LEFT OF RIDGE), AND JONES VALLEY AND CITY OF BIRMINGHAM (TO RIGHT BUT NOT PICTURED) - Red Mountain Suburbs, Crest of Red Mountain, Birmingham, Jefferson County, AL

  15. Fingerprint Ridge Count: A Polygenic Trait Useful in Classroom Instruction.

    ERIC Educational Resources Information Center

    Mendenhall, Gordon; And Others

    1989-01-01

    Describes the use of the polygenic trait of total fingerprint ridge count in the classroom as a laboratory investigation. Presents information on background of topic, fingerprint patterns which are classified into three major groups, ridge count, the inheritance model, and activities. Includes an example data sheet format for fingerprints. (RT)

  16. Oak Ridge Reservation Annual Site environmental report summary for 1994

    SciTech Connect

    1995-09-01

    This document presents a summary of the information collected for the Oak Ridge Reservation 1994 site environmental report. Topics discussed include: Oak Ridge Reservation mission; ecology; environmental laws; community participation; environmental restoration; waste management; radiation effects; chemical effects; risk to public; environmental monitoring; and radionuclide migration.

  17. 13. Whetstone Ridge. View of the restaurant and gift shop. ...

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

    13. Whetstone Ridge. View of the restaurant and gift shop. It's board-and-batten construction with a long integral shed porch across the front, a jerkinhead roof and stone chimney are a reflection of the Appalachian Culture the parkway endeavors to interpret. The view is toward the southwest. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  18. 247. Axial Parkway alignment along ridge top. Note the open ...

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

    247. Axial Parkway alignment along ridge top. Note the open vistas to either side of the roadway. These are maintained through vegetation management. The wood guide rail is a primary safety feature. View is to the northeast. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  19. Feedback control of coupled-bunch instabilities

    SciTech Connect

    Fox, J.D.; Eisen, N.; Hindi, H.; Linscott, I.; Oxoby, G.; Sapozhnikov, L.; Serio, M.

    1993-05-01

    The next generation of synchrotron light sources and particle accelerators will require active feedback systems to control multi-bunch instabilities. Stabilizing hundreds or thousands of potentially unstable modes in these accelerator designs presents many technical challenges. Feedback systems to stabilize coupled-bunch instabilities may be understood in the frequency domain (mode-based feedback) or in the time domain (bunch-by-bunch feedback). In both approaches an external amplifier system is used to create damping fields that prevent coupled-bunch oscillations from growing without bound. The system requirements for transverse (betatron) and longitudinal (synchrotron) feedback are presented, and possible implementation options developed. Feedback system designs based on digital signal-processing techniques are described. Experimental results are shown from a synchrotron oscillation damper in the SSRL/SLAC storage ring SPEAR that uses digital signal-processing techniques.

  20. Advanced information feedback in intelligent traffic systems.

    PubMed

    Wang, Wen-Xu; Wang, Bing-Hong; Zheng, Wen-Chen; Yin, Chuan-Yang; Zhou, Tao

    2005-12-01

    The optimal information feedback is very important to many socioeconomic systems like stock market and traffic systems aiming to make full use of resources. As to traffic flow, a reasonable real-time information feedback can improve the urban traffic condition by providing route guidance. In this paper, the influence of a feedback strategy named congestion coefficient feedback strategy is introduced, based on a two-route scenario in which dynamic information can be generated and displayed on the board to guide road users to make a choice. Simulation results adopting this optimal information feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other two information feedback strategies, i.e., travel time and mean velocity.

  1. Advanced information feedback in intelligent traffic systems.

    PubMed

    Wang, Wen-Xu; Wang, Bing-Hong; Zheng, Wen-Chen; Yin, Chuan-Yang; Zhou, Tao

    2005-12-01

    The optimal information feedback is very important to many socioeconomic systems like stock market and traffic systems aiming to make full use of resources. As to traffic flow, a reasonable real-time information feedback can improve the urban traffic condition by providing route guidance. In this paper, the influence of a feedback strategy named congestion coefficient feedback strategy is introduced, based on a two-route scenario in which dynamic information can be generated and displayed on the board to guide road users to make a choice. Simulation results adopting this optimal information feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other two information feedback strategies, i.e., travel time and mean velocity. PMID:16486093

  2. Advanced information feedback in intelligent traffic systems

    NASA Astrophysics Data System (ADS)

    Wang, Wen-Xu; Wang, Bing-Hong; Zheng, Wen-Chen; Yin, Chuan-Yang; Zhou, Tao

    2005-12-01

    The optimal information feedback is very important to many socioeconomic systems like stock market and traffic systems aiming to make full use of resources. As to traffic flow, a reasonable real-time information feedback can improve the urban traffic condition by providing route guidance. In this paper, the influence of a feedback strategy named congestion coefficient feedback strategy is introduced, based on a two-route scenario in which dynamic information can be generated and displayed on the board to guide road users to make a choice. Simulation results adopting this optimal information feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other two information feedback strategies, i.e., travel time and mean velocity.

  3. Galaxy-scale AGN feedback - theory

    NASA Astrophysics Data System (ADS)

    Wagner, A. Y.; Bicknell, G. V.; Umemura, M.; Sutherland, R. S.; Silk, J.

    2016-02-01

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

  4. Reducing the uncertainty in subtropical cloud feedback

    NASA Astrophysics Data System (ADS)

    Myers, Timothy A.; Norris, Joel R.

    2016-03-01

    Large uncertainty remains on how subtropical clouds will respond to anthropogenic climate change and therefore whether they will act as a positive feedback that amplifies global warming or negative feedback that dampens global warming by altering Earth's energy budget. Here we reduce this uncertainty using an observationally constrained formulation of the response of subtropical clouds to greenhouse forcing. The observed interannual sensitivity of cloud solar reflection to varying meteorological conditions suggests that increasing sea surface temperature and atmospheric stability in the future climate will have largely canceling effects on subtropical cloudiness, overall leading to a weak positive shortwave cloud feedback (0.4 ± 0.9 W m-2 K-1). The uncertainty of this observationally based approximation of the cloud feedback is narrower than the intermodel spread of the feedback produced by climate models. Subtropical cloud changes will therefore complement positive cloud feedbacks identified by previous work, suggesting that future global cloud changes will amplify global warming.

  5. Evidence for melt channelization in Galapagos plume-ridge interaction

    NASA Astrophysics Data System (ADS)

    Mittal, T.; Richards, M. A.

    2015-12-01

    Many present-day hot spots are located within ~ 1000 km of a mid-ocean ridge, either currently or in the geologic past, leading to frequent interaction between these two magmatic regimes. The consequent plume-ridge interactions provide a unique opportunity to test models for asthenosphere-lithosphere dynamics, with the plume acting as a tracer fluid in the problem, and excess magmatism reflecting otherwise unsampled sub-surface phenomena. Galapagos is an off-ridge hotspot with the mantle plume located ~150-250 km south of the plate boundary. Plume-ridge interaction in Galapagos is expressed by the formation of volcanic lineaments of islands and seamounts - e.g., the Wolf-Darwin lineament (WDL) - providing a direct probe of the plume-ridge interaction process, especially in regards to geochemical data. Although several models have been proposed to explain plume-ridge interaction in Galapagos, none adequately explain the observed characteristics, especially the WDL. In particular, predicted lithospheric fault orientations and melt density considerations appear at odds with observations, suggesting that lithospheric extension is not the primary process for formation of these islands. Other off-ridge hotspots interacting with nearby spreading ridges, such as Reunion and Louisville, also exhibit volcanic lineaments linking the plume and the ridge. Thus these lineament-type features are a common outcome of plume-ridge interaction that are indicative of the underlying physics. We propose that the lineaments are surface expressions of narrow sub-lithospheric melt channels focused towards the spreading ridge. These channels should form naturally due to the reactive infiltration instability in a two-phase flow of magma and solid mantle as demonstrated in two-phase flow simulations (e.g., Katz & Weatherley 2012). For Galapagos, we show that melt channels can persist thermodynamically over sufficient length-scales to link the plume and nearby ridge segments. We also show that

  6. Revisiting the Ridge-Push Force Using the Lithospheric Geoid

    NASA Astrophysics Data System (ADS)

    Richardson, R. M.; Coblentz, D. D.

    2014-12-01

    The geoid anomaly and driving force associated with the cooling oceanic lithosphere ("ridge push") are both proportional to dipole moment of the density-depth distribution, and allow a reevaluation of the ridge push force using the geoid. The challenge with this approach is to isolate the "lithospheric geoid" from the full geoid signal. Our approach is to use a band-pass spherical harmonic filter on the full geoid (e.g., EGM2008-WGS84, complete to spherical harmonic degree and order 2159) between orders 6 and 80. However, even this "lithospheric geoid" is noisy, and thus we average over 100 profiles evenly spaced along the global ridge system to obtain an average geoid step associated with the mid-ocean ridges. Because the positive ridge geoid signal is largest near the ridge (and to capture fast-spreading ridges), we evaluate symmetrical profiles extending ±45 m.y. about the ridge. We find an average ridge geoid anomaly of 4.5m, which is equivalent to a 10m anomaly for 100 m.y. old oceanic lithosphere. This geoid step corresponds to a ridge push force of ~2.4 x1012N/m for old oceanic lithosphere of 100 m.y., very similar to earlier estimates of ~2.5 x1012N/m based on simple half-space models. This simple half-space model also predicts constant geoid slopes of about 0.15 m/m.y. for cooling oceanic lithosphere. Our observed geoid slopes are consistent with this value for ages up to 40-50 m.y., but drop off to lower values at greater ages. We model this using a plate cooling model (with a thickness of the order of 125km) to fit the observation that the geoid anomaly and ridge driving force only increase slowly for ages greater than 40 m.y. (in contrast to the half-space model where the linear dependence on age holds for all ages). This reduction of the geoid slope results in a 20% decrease in the predicted ridge push force. This decrease is due to the combined effects of treating the oceanic lithosphere as a cooling plate (vs. a half-space), and the loss of geoidal

  7. Connecting tubule glomerular feedback antagonizes tubuloglomerular feedback in vivo.

    PubMed

    Wang, H; Garvin, J L; D'Ambrosio, M A; Ren, Y; Carretero, O A

    2010-12-01

    In vitro experiments showed that the connecting tubule (CNT) sends a signal that dilates the afferent arteriole (Af-Art) when Na(+) reabsorption in the CNT lumen increases. We call this process CNT glomerular feedback (CTGF) to differentiate it from tubuloglomerular feedback (TGF), which is a cross talk between the macula densa (MD) and the Af-Art. In TGF, the MD signals the Af-Art to constrict when NaCl transport by the MD is enhanced by increased luminal NaCl. CTGF is mediated by CNT Na(+) transport via epithelial Na(+) channels (ENaC). However, we do not know whether CTGF occurs in vivo or whether it opposes the increase in Af-Art resistance caused by TGF. We hypothesized that CTGF occurs in vivo and opposes TGF. To test our hypothesis, we conducted in vivo micropuncture of individual rat nephrons, measuring stop-flow pressure (P(SF)) as an index of glomerular filtration pressure. To test whether activation of CTGF opposes TGF, we used benzamil to block CNT Na(+) transport and thus CTGF. CTGF inhibition with the ENaC blocker benzamil (1 μM) potentiated the decrease in P(SF) at 40 and 80 nl/min. Next, we tested whether we could augment CTGF by inhibiting NaCl reabsorption in the distal convoluted tubule with hydrochlorothiazide (HCTZ, 1 mM) to enhance NaCl delivery to the CNT. In the presence of HCTZ, benzamil potentiated the decrease in P(SF) at 20, 40, and 80 nl/min. We concluded that in vivo CTGF occurs and opposes the vasoconstrictor effect of TGF. PMID:20826574

  8. Tactile feedback improves auditory spatial localization.

    PubMed

    Gori, Monica; Vercillo, Tiziana; Sandini, Giulio; Burr, David

    2014-01-01

    Our recent studies suggest that congenitally blind adults have severely impaired thresholds in an auditory spatial bisection task, pointing to the importance of vision in constructing complex auditory spatial maps (Gori et al., 2014). To explore strategies that may improve the auditory spatial sense in visually impaired people, we investigated the impact of tactile feedback on spatial auditory localization in 48 blindfolded sighted subjects. We measured auditory spatial bisection thresholds before and after training, either with tactile feedback, verbal feedback, or no feedback. Audio thresholds were first measured with a spatial bisection task: subjects judged whether the second sound of a three sound sequence was spatially closer to the first or the third sound. The tactile feedback group underwent two audio-tactile feedback sessions of 100 trials, where each auditory trial was followed by the same spatial sequence played on the subject's forearm; auditory spatial bisection thresholds were evaluated after each session. In the verbal feedback condition, the positions of the sounds were verbally reported to the subject after each feedback trial. The no feedback group did the same sequence of trials, with no feedback. Performance improved significantly only after audio-tactile feedback. The results suggest that direct tactile feedback interacts with the auditory spatial localization system, possibly by a process of cross-sensory recalibration. Control tests with the subject rotated suggested that this effect occurs only when the tactile and acoustic sequences are spatially congruent. Our results suggest that the tactile system can be used to recalibrate the auditory sense of space. These results encourage the possibility of designing rehabilitation programs to help blind persons establish a robust auditory sense of space, through training with the tactile modality. PMID:25368587

  9. Fuzzy cloud concepts for assessing radiation feedbacks

    SciTech Connect

    Hanson, H.

    1995-09-01

    The importance of clouds in the climate system is well-known but poorly understood. Modeling and observational studies have suggested that there may be positive feedbacks associated with certain cloud processes, but it is not known how strong these feedbacks are in the context of the overall system. Examples include ice microphysics feedback, as shown by Liou`s model, and the relationship between SST and cloud cover in the tropics, which is the focus of this research. 2 refs., 3 figs.

  10. Representation of feedback operators for hyperbolic systems

    NASA Technical Reports Server (NTRS)

    Burns, John A.; King, Belinda B.

    1995-01-01

    We consider the problem of obtaining integral representation of feedback operators for damped hyperbolic control systems. We show that for the wave equation with Kelvin-Voigt damping and non-compact input operator, the feedback gain operator is Hilbert-Schmidt. This result is then used to provide an explicit integral representation for the feedback operator in terms of functional gains. Numerical results are given to illustrate the role that damping plays in the smoothness of these gains.

  11. Chemical signatures from hydrothermal venting on slow spreading ridges

    NASA Astrophysics Data System (ADS)

    Edmonds, Henrietta N.

    At least 24 sites of active venting have been confirmed on slow and ultraslow spreading ridges, with dozens more indicated on the basis of hydrothermal plume distributions and/or dredge recovery of massive sulfides. Fluid chemistry data have been published for 13 sites: 8 on the northern Mid-Atlantic Ridge, 3 on the southern Mid-Atlantic Ridge, and 2 on the Central Indian Ridge. Three of these 13 sites (Rainbow, Logatchev, and Lost City) are known to be hosted in ultramafic terrain, and their fluid chemistries reflect the influence of serpentinization reactions, including elevated hydrogen and methane, and low silica concentrations. This brief review presents the published fluid chemistry for all 13 sites, including time series where available, and demonstrates the diversity of chemical compositions engendered by the myriad settings (near and off axis, young volcanic to ultramafic terrain, and depths up to 4100 m) of hydrothermal systems on slow and ultraslow spreading ridges.

  12. Black smokers on the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Rona, Peter A.

    Evidence for a variety of active hydrothermal venting phenomena, including black smokers, was discovered at a site on the Mid-Atlantic Ridge by a research team of government and university scientists. The work was accomplished on a cruise of the National Oceanic and Atmospheric Administration (NOAA) ship Researcher during July 1985 as part of the NOAA Vents Program. The site of the venting phenomena is the Trans-Atlantic Geotraverse (TAG) Hydrothermal Field on the east wall of the rift valley of the Mid-Atlantic Ridge at 26°N. The TAG Hydrothermal Field was the first hydrothermal field to be found on an oceanic ridge; it was discovered 12 years ago in 1973. However, until the present cruise, only low-temperature hydrothermal activity had been documented, and the existence of higher-temperature hydrothermal activity along slow spreading oceanic ridges (half rate 2 cm/yr), such as the Mid-Atlantic Ridge, was in question.

  13. Oak Ridge Reservation environmental report for 1989

    SciTech Connect

    Jacobs, V.A.; Wilson, A.R.

    1990-10-01

    The first two volumes of this report are devoted to a presentation of environmental data and supporting narratives for the US Department of Energy's (DOE's) Oak Ridge Reservation (ORR) and surrounding environs during 1989. Volume 1 includes all narrative descriptions, summaries, and conclusions and is intended to be a stand-alone'' report for the ORR for the reader who does not want to review in detail all of the 1989 data. Volume 2 includes the detailed data summarized in a format to ensure that all environmental data are represented in the tables. Narratives are not included in Vol. 2. The tables in Vol. 2 are addressed in Vol. 1. For this reason, Vol. 2 cannot be considered a stand-alone report but is intended to be used in conjunction with Vol. 1. 16 figs., 194 tabs.

  14. Oak Ridge Reservation Environmental report for 1990

    SciTech Connect

    Wilson, A.R.

    1991-09-01

    The first two volumes of this report are devoted to a presentation of environmental data and supporting narratives for the US Department of Energy's (DOE's) Oak Ridge Reservation (ORR) and surrounding environs during 1990. Volume 1 includes all narrative descriptions, summaries, and conclusions and is intended to be a stand-alone'' report for the ORR for the reader who does not want to review in detail all of the 1990 data. Volume 2 includes the detailed data summarized in a format to ensure that all environmental data are represented in the tables. Narratives are not included in Vol. 2. The tables in Vol. 2 are addressed in Vol. 1. For this reason, Vol. 2 cannot be considered a stand-alone report but is intended to be used in conjunction with Vol. 1.

  15. Oak Ridge Reservation environmental report for 1988

    SciTech Connect

    Prince, N.L.

    1989-05-01

    The first two volumes of this report are devoted to a presentation of environmental data and supporting narratives for the US Department of Energy's (DOE's) Oak Ridge Reservation (ORR) and surrounding environs during 1988. Volume 1 includes all narrative descriptions, summaries, and conclusions and is intended to be a stand-alone'' report for the ORR for the reader who does not want to review in detail all of the 1988 data. Volume 2 includes the detailed data summarized in a format to ensure that all environmental data are represented in the tables. Narratives are not included in Volume 2. The tables in Volume 2 are addressed in Volume 1. For this reason, Vol. 2 cannot be considered a stand-alone report but is intended to be used in conjunction with Volume 1.

  16. FOSSIL RIDGE WILDERNESS STUDY AREA, COLORADO.

    USGS Publications Warehouse

    DeWitt, Ed; Kluender, Steven E.

    1984-01-01

    The Fossil Ridge Wilderness Study Area, approximately 20 mi northeast of Gunnison in central Colorado, was studied and its mineral-resource potential assessed. Portions of the study area have substantiated resource potential for gold, silver, copper, lead, zinc, molybdenum, uranium, thorium, rare-earth elements, and high-calcium limestone. Much of the area has a probable resource potential for the preceeding commodities as well as for tin. Various other elements are found in anomalous concentrations within the study area, but there is likelihood for their occurrence in amounts sufficient to constitute resources. Exploration, especially for molybdenum, gold, and uranium, has been active in the past and is expected to continue in the future. No potential for fossil fuel resources was identified in this study.

  17. Reactive spreading: Adsorption, ridging and compound formation

    SciTech Connect

    Saiz, E.; Cannon, R.M.; Tomsia, A.P.

    2000-09-11

    Reactive spreading, in which a chemically active element is added to promote wetting of noble metals on nonmetallic materials, is evaluated. Theories for the energetics and kinetics of the necessary steps involved in spreading are outlined and compared to the steps in compound formation that typically accompany reactive wetting. These include: fluid flow, active metal adsorption, including nonequilibrium effects, and triple line ridging. All of these can be faster than compound nucleation under certain conditions. Analysis and assessment of recently reported experiments on metal/ceramic systems lead to a focus on those conditions under which spreading proceeds ahead of the actual formation of a new phase at the interface. This scenario may be more typical than believed, and perhaps the most effective situation leading to enhanced spreading. A rationale for the pervasive variability and hysteresis observed during high temperature wetting also emerges.

  18. Ocean mixing studied near Hawaiian Ridge

    NASA Astrophysics Data System (ADS)

    Pinkel, Robert; Munk, Walter; Worcester, Peter; Comuelle, Bruce D.; Rudnick, Daniel; Sherman, Jeffrey; Filloux, Jean H.; Dushaw, Brian D.; Howe, Bruce M.; Sanford, Thomas B.; Lee, Craig M.; Kunze, Eric; Gregg, Michael C.; Miller, Jack B.; Merrifield, Mark A.; Luther, Douglas S.; Firing, Eric; Brainard, Rusty; Flament, Pierre J.; Chave, Alan D.; Moum, James M.; Caldwell, Douglas R.; Levine, Murray D.; Boyd, Timothy; Egbert, Gary D.

    The Hawaii Ocean Mixing Experiment (HOME) is a grassroots program to study turbulent mixing processes near the Hawaiian Ridge. The HOME is motivated by the desire to understand diffusive aspects of the advective-diffusive balance that mediates the general circulation of the oceans. HOME is focused on tidally driven mixing, given the ubiquity of the tide as a deep-sea energy source.As the sea surface cools at high latitude, surface waters sink. Subsidence rate is sufficient to fill the worlds ocean with cold bottom water in approximately 3,000 years. Diffusive processes that transfer heat into the abyssal ocean are required to maintain a steady-state thermal structure. An effective eddy diffusivity of order Kp=10-4 m2 s-1, 700 times the molecular diffusivity of heat, is necessary [Munk, 1966]. Such a diffusivity might be supported by either mechanical mixing (turbulent transport) or thermodynamic (so-called doubly diffusive) processes.

  19. Source document for waste area groupings at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Osborne, P.L.; Kuhaida, A.J., Jr.

    1996-09-01

    This document serves as a source document for Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and other types of documents developed for and pertaining to Environmental Restoration (ER) Program activities at Oak Ridge National Laboratory (ORNL). It contains descriptions of the (1) regulatory requirements for the ORR ER Program, (2) Oak Ridge Reservation (ORR) ER Program, (3) ORNL site history and characterization, and (4) history and characterization of Waste Area Groupings (WAGS) 1-20. This document was created to save time, effort, and money for persons and organizations drafting documents for the ER Program and to improve consistency in the documents prepared for the program. By eliminating the repetitious use of selected information about the program, this document will help reduce the time and costs associated with producing program documents. By serving as a benchmark for selected information about the ER Program, this reference will help ensure that information presented in future documents is accurate and complete.

  20. Oak Ridge Health Studies phase 1 report, Volume 1: Oak Ridge Phase 1 overview

    SciTech Connect

    Yarbrough, M.I.; Van Cleave, M.L.; Turri, P.; Daniel, J.

    1993-09-01

    In July 1991, the State of Tennessee initiated the Health Studies Agreement with the United States Department of Energy to carry out independent studies of possible adverse health effects in people living in the vicinity of the Oak Ridge Reservation. The health studies focus on those effects that could have resulted or could result from exposures to chemicals and radioactivity released at the Reservation since 1942. The major focus of the first phase was to complete a Dose Reconstruction Feasibility Study. This study was designed to find out if enough data exist about chemical and radionuclide releases from the Oak Ridge Reservation to conduct a second phase. The second phase will lead to estimates of the actual amounts or the ``doses`` of various contaminants received by people as a result of off-site releases. Once the doses of various contaminants have been estimated, scientists and physicians will be better able to evaluate whether adverse health effects could have resulted from the releases.

  1. Melton Valley Storage Tanks Capacity Increase Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1995-04-01

    The US Department of Energy (DOE) proposes to construct and maintain additional storage capacity at Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee, for liquid low-level radioactive waste (LLLW). New capacity would be provided by a facility partitioned into six individual tank vaults containing one 100,000 gallon LLLW storage tank each. The storage tanks would be located within the existing Melton Valley Storage Tank (MVST) facility. This action would require the extension of a potable water line approximately one mile from the High Flux Isotope Reactor (HFIR) area to the proposed site to provide the necessary potable water for the facility including fire protection. Alternatives considered include no-action, cease generation, storage at other ORR storage facilities, source treatment, pretreatment, and storage at other DOE facilities.

  2. Improved feedback amplifier for electromagnetic induction sensors

    NASA Astrophysics Data System (ADS)

    Scott, Waymond R.

    2016-05-01

    A method using feedback is presented that reduces several measurement errors inherent in electromagnetic induction sensors. Errors associated with coupling between receive coils and errors associated with operating near magnetic soils will both be reduced. The method uses feedback that is directly injected into the receive coils and does not require secondary coils. A simple circuit is introduced to perform the feedback and is optimized to reduce the errors and make the circuit stable. Experimental results are presented to show the effectiveness of the feedback.

  3. Can corrective feedback improve recognition memory?

    PubMed

    Kantner, Justin; Lindsay, D Stephen

    2010-06-01

    An understanding of the effects of corrective feedback on recognition memory can inform both recognition theory and memory training programs, but few published studies have investigated the issue. Although the evidence to date suggests that feedback does not improve recognition accuracy, few studies have directly examined its effect on sensitivity, and fewer have created conditions that facilitate a feedback advantage by encouraging controlled processing at test. In Experiment 1, null effects of feedback were observed following both deep and shallow encoding of categorized study lists. In Experiment 2, feedback robustly influenced response bias by allowing participants to discern highly uneven base rates of old and new items, but sensitivity remained unaffected. In Experiment 3, a false-memory procedure, feedback failed to attenuate false recognition of critical lures. In Experiment 4, participants were unable to use feedback to learn a simple category rule separating old items from new items, despite the fact that feedback was of substantial benefit in a nearly identical categorization task. The recognition system, despite a documented ability to utilize controlled strategic or inferential decision-making processes, appears largely impenetrable to a benefit of corrective feedback.

  4. Cloud feedback on climate change and variability

    NASA Astrophysics Data System (ADS)

    Zhou, C.; Dessler, A. E.; Yang, P.

    2014-12-01

    Cloud feedback on climate change and variability follow similar mechanism in climate models, and the magnitude of cloud feedback on climate change and variability are well correlated among models. Therefore, the cloud feedback on short-term climate fluctuations correlates with the equilibrium climate sensitivity in climate models. Using this correlation and the observed short-term climate feedback, we infer a climate sensitivity of ~2.9K. The cloud response to inter-annual surface warming is generally consistent in observations and climate models, except for the tropical boundary-layer low clouds.

  5. Modal insensitivity with optimality. [in feedback control

    NASA Technical Reports Server (NTRS)

    Calise, A. J.; Raman, K. V.

    1984-01-01

    This paper deals with the design of a constant gain, feedback controller which results in selected modal insensitivity, and at the same time optimizes a quadratic performance index representative of desired system performance for nominal plant parameter values. Both full state and output feedback control are considered. A constraint is established for the feedback gain matrix that results in modal insensitivity, and necessary conditions for optimality subject to this constraint are given. This forms the basis for a numerical algorithm to compute the optimal feedback gain. To illustrate the procedure, a design is carried out using the lateral dynamics of an L-1011 aircraft.

  6. Ridges swimming in a sea of dust

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    The muted terrain of northern Acidalia Planitia testifies to the fact that the region is heavily mantled with dust. The most interesting features in this image are the small terraces located along the flanks of the ridges and the patterned ground seen at the base of the largest ridge (upper right). These features appear to be classic examples of periglacial landforms and may indicate the presence of shallow subsurface ice.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

    Image information: VIS instrument. Latitude 54.9, Longitude 351 East (9 West). 19 meter/pixel resolution.

  7. Hydrothermal activity at the Arctic mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Pedersen, Rolf B.; Thorseth, Ingunn H.; Nygård, Tor Eivind; Lilley, Marvin D.; Kelley, Deborah S.

    Over the last 10 years, hydrothermal activity has been shown to be abundant at the ultraslow spreading Arctic Mid-Ocean Ridges (AMOR). Approximately 20 active and extinct vent sites have been located either at the seafloor, as seawater anomalies, or by dredge sampling hydrothermal deposits. Decreasing spreading rates and decreasing influence of the Icelandic hot spot toward the north along the AMOR result in a north-south change from a shallow and magmatically robust to a deep and magmatically starved ridge system. This contrast gives rise to large variability in the ridge geology and in the nature of the associated hydrothermal systems. The known vent sites at the southern part of the ridge system are either low-temperature or white smoker fields. At the deep, northern parts of the ridge system, a large black smoker field has been located, and seawater anomalies and sulfide deposits suggest that black smoker-type venting is common. Several of these fields may be peridotite-hosted. The hydrothermal activity at parts of the AMOR exceeds by a factor of 2 to 3 what would be expected by extrapolating from observations on faster spreading ridges. Higher fracture/fault area relative to the magma volume extracted seems a likely explanation for this. Many of the vent fields at the AMOR are associated with axial volcanic ridges. Strong focusing of magma toward these ridges, deep rifting of the ridges, and subsequent formation of long-lived detachment faults that are rooted below the ridges may be the major geodynamic mechanisms causing the unexpectedly high hydrothermal activity.

  8. Tiger team assessment of the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    none,

    1990-02-01

    This document contains findings identified during the Tiger Team Compliance Assessment of the Department of Energy's (DOE's) Y-12 Plant in Oak Ridge, Tennessee. The Y-12 Plant Tiger Team Compliance Assessment is comprehensive in scope. It covers the Environmental, Safety, and Health (including Occupational Safety and Health Administration (OSHA) compliance), and Management areas and determines the plant's compliance with applicable federal (including DOE), state, and local regulations and requirements. 4 figs., 12 tabs.

  9. Removal action report on the Building 3001 canal at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1997-05-01

    Oak Ridge National Laboratory (ORNL) is a federal facility managed by Lockheed Martin C, Energy Research, Inc., for the U.S. Department of Energy (DOE). ORNL on the Oak Ridge Reservation in East Tennessee at the Anderson and Roane County lines, approximately 38 km (24 miles) west of Knoxville, Tennessee, and 18 km (11 miles) southwest of downtown Oak Ridge. The Oak Ridge Graphite Reactor and its storage and transfer canal are located in Bldg. 3001 in the approximate center of Waste Area Grouping I in the ORNL main complex. 4:1 The Bldg. 3001 Storage Canal is an L-shaped, underground, reinforced-concrete structure running from the back and below the Graphite Reactor in Bldg. 3001 to a location beneath a hot cell in the adjacent Bldg. 3019. The Graphite Reactor was built in 1943 to produce small quantities of plutonium and was subsequently used to produce other isotopes for medical research before it was finally shut down in 1963. The associated canal was used to transport, under water, spent fuel slugs and other isotopes from the back of the reactor to the adjacent Bldg. 31319 hot cell for further processing. During its operation and years subsequent to operation, the canal`s concrete walls and floor became contaminated with radioisotopes from the water.This report documents the activities involved with replacing the canal water with a solid, controlled, low-strength material (CLSM) in response to a Comprehensive Environmental Response, Compensation, and Liability Act non-time-critical removal action.

  10. Geological mapping of the Oak Ridge K-25 Site, Oak Ridge, Tennessee

    SciTech Connect

    Lemiszki, P.J.

    1994-01-01

    The Oak Ridge K-25 Site (formerly known as the Oak Ridge Gaseous Diffusion Plant) is located in the southern Appalachian Valley and Ridge province of east Tennessee and overlies an area of folded and faulted Cambrian through Ordovician sedimentary rocks in the footwall of the Whiteoak Mountain fault. Environmental restoration plans for the area require that the geology of the site be well understood because various aspects of the groundwater system are directly influenced by stratigraphic and structural characteristics of the bedrock. This study involved mapping the bedrock geology of an 18-square mile area in and around the plant site. Field mapping focused on: (1) checking the accuracy of previously mapped stratigraphic and fault contacts, (2) dividing the bedrock into distinct stratigraphic units based on field criteria, (3) determining the geometry of map-scale folds and faults, and (4) documenting various aspects of the local fracture system. Besides accomplishing all of the above tasks, results from this study have led to a number of new hypotheses regarding various aspects of the site geology. First, faulting and folding within carbonates of the Chickamauga Supergroup in the plant area has repeated certain rock units, which requires that there be a thrust fault in the subsurface below them. This thrust fault may project to the surface with the Carters Limestone. Second, thrust slices of the Rome Formation that overlie the Chickamauga carbonates may be extremely thin and have a limited aerial extent. Third, part of the Knox Group on McKinney Ridge is folded into an anticline. Evaluating the above hypotheses will require information about the subsurface that can only be acquired through drilling and surface geophysical surveys. The geologic map produced from this study can be used to evaluate the location of coreholes that will more effectively intersect a combination of stratigraphic, structural, and hydrologic targets.

  11. Site descriptions of environmental restoration units at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Kuhaida, A.J. Jr.; Parker, A.F.

    1997-02-01

    This report provides summary information on Oak Ridge National Laboratory (ORNL) Environmental Restoration (ER) sites as listed in the Oak Ridge Reservation Federal Facility Agreement (FFA), dated January 1, 1992, Appendix C. The Oak Ridge National Laboratory was built in 1943 as part of the World War II Manhattan Project. The original mission of ORNL was to produce and chemically separate the first gram-quantities of plutonium as part of the national effort to produce the atomic bomb. The current mission of ORNL is to provide applied research and development in support of the U.S. Department of Energy (DOE) programs in nuclear fusion and fission, energy conservation, fossil fuels, and other energy technologies and to perform basic scientific research in selected areas of the physical, life, and environmental sciences. ER is also tasked with clean up or mitigation of environmental impacts resulting from past waste management practices on portions of the approximately 37,000 acres within the Oak Ridge Reservation (ORR). Other installations located within the ORR are the Gaseous Diffusion Plant (K-25) and the Y-12 plant. The remedial action strategy currently integrates state and federal regulations for efficient compliance and approaches for both investigations and remediation efforts on a Waste Area Grouping (WAG) basis. As defined in the ORR FFA Quarterly Report July - September 1995, a WAG is a grouping of potentially contaminated sites based on drainage area and similar waste characteristics. These contaminated sites are further divided into four categories based on existing information concerning whether the data are generated for scoping or remedial investigation (RI) purposes. These areas are as follows: (1) Operable Units (OU); (2) Characterization Areas (CA); (3) Remedial Site Evaluation (RSE) Areas; and (4) Removal Site Evaluation (RmSE) Areas.

  12. The Davie Ridge: a Marginal Transform Ridge not Formed During Continental Breakup

    NASA Astrophysics Data System (ADS)

    Phethean, J. J. J.; Van Hunen, J.; McCaffrey, K. J. W.; Davies, R. J.

    2014-12-01

    The breakup of Gondwana translated Madagascar southwards relative to Africa along the Davie Fracture Zone (DFZ). This fracture zone now forms the Transform Passive Continental Margin (TPCM) from Kenya to Mozambique. The Davie Ridge (DR), a transform marginal ridge, has formed along the DFZ between 5 and 2°S and 22 and 11°S, but with little expression in-between. It has been proposed that this marginal ridge was formed by the thermal effects of a passing Mid Ocean Ridge (MOR) during the separation of Gondwana. Plate kinematic reconstructions, however, constrained by ocean magnetic anomalies, show that the MOR only passed between the north and south expressions of the DR. Therefore the positive linear gravity anomalies of the DR cannot be attributed to the effects of a passing MOR, and some other mechanism must be found to explain their formation. Interpretation of seismic reflection profiles along the DR shows that the gravity highs occur adjacent to large basin structures. In the north this correlates with a basin-bounding basement high of ~Albian age, and in the south with the rift flank uplifts of the currently active Quirimbas graben. This suggests that the northern and southern DR segments are instead shoulder uplifts resulting from two separate extensional episodes during different stress regimes. These are the Cretaceous NE-SW extension during the breakup of the south Atlantic, and the E-W extension of the Neogene-recent Afar-East Africa rift system, respectfully. The lack of deformation and DR formation along the region of the TPCM passed by the MOR suggests it has been coupled by thermal effects and/or the injection of magma.

  13. The Effect of Ridge Expansion on Implant Stability in Narrow Partially Edentulous Ridges - A Preliminary Clinical Study

    PubMed Central

    Shaik, Latheef Saheb; Meka, Sridhar; Chakravarthi, Srinivas Pandi; Kolli, Naga Neelima Devi; Lingamaneni, Krishna Prasad; Avvaru, Susmita; Tiwari, Rahul

    2016-01-01

    Introduction Currently, dental treatments with better aesthetic results and less treatment time is more acceptable by the patients. Inadequate amount of bone for implant placement at functionally and aesthetically most appropriate position is a common problem. Aim To assess the effect of ridge expansion on implant stability in narrow partially edentulous ridges and to evaluate clinically and radiographically the success of dental implants, placed immediately following ridge expansion procedure. Material and Methods Ten participants (nine males, one female, average age - 28 years) with partial edentulism associated with narrow atrophic alveolar ridges with adequate height and willing to participate in the study were included. The ridge expansion was performed using osteotomes and simultaneous implant placement was done. A total of 10 implants were placed. Stability, achieved ridge width and radiographic crestal bone loss were assessed three months post-operatively. Results Three months follow-up revealed stable implants both clinically and radiographically. All 10 implants were surrounded by adequate amount of bone required for successful functional rehabilitation. Conclusion The study reveals that the technique of ridge expansion using osteotomes is successful in horizontal expansion, in cases of atrophic alveolar ridges thus, eliminating the need for more complex treatment as well as reduces the rehabilitation time along with improving the quality of bone support. PMID:27790575

  14. Microgravity survey of the Oak Ridge K-25 Site, Oak Ridge, Tennessee

    SciTech Connect

    Kaufmann, R.D.

    1996-05-01

    Karst features are known to exist within the carbonate bedrock of the Oak Ridge K-25 Site and may play an important role in groundwater flow and contaminant migration. This report discusses the results of a microgravity survey of the Oak Ridge K-25 Site. The main objective of the survey is to identify areas containing bedrock cavities. Secondary objectives included correlating the observed gravity to the geology and to variations in overburden thickness. The analysis includes 11 profile lines that are oriented perpendicular to the geologic strike and major structures throughout the K-25 Site. The profile lines are modeled in an effort to relate gravity anomalies to karst features such as concentrations of mud-filled cavities. Regolith thickness and density data provided by boreholes constrain the models. Areally distributed points are added to the profile lines to produce a gravity contour map of the site. In addition, data from the K-901 area are combined with data from previous surveys to produce a high resolution map of that site. The K-25 Site is located in an area of folded and faulted sedimentary rocks within the Appalachian Valley and Ridge physiographic province. Paleozoic age rocks of the Rome Formation, Knox Group, and Chickamauga Supergroup underlie the K-25 Site and contain structures that include the Whiteoak Mountain Fault, the K-25 Fault, a syncline, and an anticline. The mapped locations of the rock units and complex structures are currently derived from outcrop and well log analysis.

  15. Site descriptions of environmental restoration units at the Oak Ridge K-25 Site, Oak Ridge, Tennessee

    SciTech Connect

    Goddard, P.L.; Legeay, A.J.; Pesce, D.S.; Stanley, A.M.

    1995-11-01

    This report, Site Descriptions of Environmental Restoration Units at the Oak Ridge K-25 Site, Oak Ridge, Tennessee, is being prepared to assimilate information on sites included in the Environmental Restoration (ER) Program of the K-25 Site, one of three major installations on the Oak Ridge Reservation (ORR) built during World War III as part of the Manhattan Project. The information included in this report will be used to establish program priorities so that resources allotted to the K-25 ER Program can be best used to decrease any risk to humans or the environment, and to determine the sequence in which any remedial activities should be conducted. This document will be updated periodically in both paper and Internet versions. Units within this report are described in individual data sheets arranged alphanumerically. Each data sheet includes entries on project status, unit location, dimensions and capacity, dates operated, present function, lifecycle operation, waste characteristics, site status, media of concern, comments, and references. Each data sheet is accompanied by a photograph of the unit, and each unit is located on one of 13 area maps. These areas, along with the sub-area, unit, and sub-unit breakdowns within them, are outlined in Appendix A. Appendix B is a summary of information on remote aerial sensing and its applicability to the ER program.

  16. Adaptive feedback cancellation in hearing aids with clipping in the feedback path.

    PubMed

    Freed, Daniel J

    2008-03-01

    Adaptive linear filtering algorithms are commonly used to cancel feedback in hearing aids. The use of these algorithms is based on the assumption that the feedback path is linear, so nonlinearities in the feedback path may affect performance. This study investigated the effect on feedback canceller performance of clipping of the feedback signal arriving at the microphone, as well as the benefit of applying identical clipping to the cancellation signal so that the cancellation path modeled the nonlinearity of the feedback path. Feedback signal clipping limited the amount of added stable gain that the feedback canceller could provide, and caused misadjustment in response to high-level inputs, by biasing adaptive filter coefficients toward lower magnitudes. Cancellation signal clipping mitigated these negative effects, permitting higher amounts of added stable gain and less misadjustment in response to high-level inputs, but the benefit was reduced in the presence of the highest-level inputs. PMID:18345849

  17. Feedback May Harm: Role of Feedback in Probabilistic Decision Making of Adolescents with ADHD.

    PubMed

    Pollak, Yehuda; Shoham, Rachel

    2015-10-01

    Inept probabilistic decision making is commonly associated with ADHD. In experimental designs aimed to model probabilistic decision making in ADHD, feedback following each choice was, in the majority of studies, part of the paradigm. This study examined whether feedback processing plays a role in the maladaptive choice behavior of subjects with ADHD by comparing feedback and no-feedback conditions. Sixty adolescents (49 males), ages 13-18, with and without ADHD, performed a descriptive probabilistic choice task in which outcomes and probabilities were explicitly provided. Subjects performed the task either with or without feedback. Under the no-feedback condition, adolescents with ADHD and controls performed similarly, whereas under the feedback condition, subjects with ADHD chose the unfavorable outcomes more frequently and risked smaller sums than controls. These finding demonstrate the crucial role of feedback in the decision making of adolescents with ADHD.

  18. Stress reduces use of negative feedback in a feedback-based learning task.

    PubMed

    Petzold, Antje; Plessow, Franziska; Goschke, Thomas; Kirschbaum, Clemens

    2010-04-01

    In contrast to the well-established effects of stress on learning of declarative material, much less is known about stress effects on reward- or feedback-based learning. Differential effects on positive and negative feedback especially have received little attention. The objective of this study, thus, was to investigate effects of psychosocial stress on feedback-based learning with a particular focus on the use of negative and positive feedback during learning. Participants completed a probabilistic selection task in both a stress and a control condition. The task allowed quantification of how much participants relied on positive and negative feedback during learning. Although stress had no effect on general acquisition of the task, results indicate that participants used negative feedback significantly less during learning after stress compared with the control condition. An enhancing effect of stress on use of positive feedback failed to reach significance. These findings suggest that stress acts differentially on the use of positive and negative feedback during learning.

  19. Human factors in telemanipulation: Perspectives from the Oak Ridge National Laboratory experience

    SciTech Connect

    Draper, J.V.

    1994-01-01

    Personnel at the Robotics and Process Systems Division (RPSD) of the Oak Ridge National Laboratory (ORNL) have extensive experience designing, building, and operating teleoperators for a variety of settings, including space, battlefields, nuclear fuel reprocessing plants, and hazardous waste retrieval. In the course of the last decade and a half, the RPSD designed, built, and operated 4 telemanipulators (M-2, ASM, LTM, CESAR arm) and operated another half dozen (M-8, Model 50, TOS SM-229, RM-10, PaR 5000, BilArm 83A). During this period, human factors professionals have been closely integrated with RPSD design teams, investigating telemanipulator feedback and feed forward, designing cockpits and control rooms, training users and designers, and helping to develop performance specifications for telemanipulators. This paper presents a brief review of this and other work, with an aim towards providing perspectives on some of the human factors aspects of telemanipulation. The first section of the paper examines user tasks during supervisory control and discusses how telemanipulator responsiveness determines the appropriate control metaphor for continuous manual control. The second section provides an ecological perspective on telemanipulator feedback and feed-forward. The third section briefly describes the RPSD control room design approach and how design projects often serve as systems integrators.

  20. UWB communication receiver feedback loop

    DOEpatents

    Spiridon, Alex; Benzel, Dave; Dowla, Farid U.; Nekoogar, Faranak; Rosenbury, Erwin T.

    2007-12-04

    A novel technique and structure that maximizes the extraction of information from reference pulses for UWB-TR receivers is introduced. The scheme efficiently processes an incoming signal to suppress different types of UWB as well as non-UWB interference prior to signal detection. Such a method and system adds a feedback loop mechanism to enhance the signal-to-noise ratio of reference pulses in a conventional TR receiver. Moreover, sampling the second order statistical function such as, for example, the autocorrelation function (ACF) of the received signal and matching it to the ACF samples of the original pulses for each transmitted bit provides a more robust UWB communications method and system in the presence of channel distortions.

  1. 78 FR 69447 - Agency Information Collection Activities; Existing Collection, Comments Requested: Friction Ridge...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-19

    ... Requested: Friction Ridge Cards: Arrest and Institution; Applicant; Personal Identification; FBI Standard... form/collection: Friction Ridge Cards: Arrest and Institution; Applicant; Personal Identification;...

  2. Multimedia Feedback Systems for Engineering

    SciTech Connect

    Gladwell, S.; Gottlieb, E.J.; McDonald, M.J.; Slutter, C.L.

    1998-12-15

    The World Wide Web has become a key tool for information sharing. Engineers and scientists are finding that the web is especially suited to publishing the graphical, multi-layered information that is typical of their work. Web pages are easier to distribute than hardcopy. Web movies have become more accessible, in many offices, than videos. Good VRML viewing software, bundled with most new PCs, has sufficient power to support many engineering needs. In addition to publishing information science and engineering has an important tradition of peer and customer review. Reports, drawings and graphs are typically printed, distributed, reviewed, marked up, and returned to the author. Adding review comments to paper is easy. When, however, the information is in electronic form, this ease of review goes away. It's hard to write on videos. It's even harder to write comments on animated 3D models. These feedback limitations reduce the value of the information overall. Fortunately, the web can also be a useful tool for collecting peer and customer review information. When properly formed, web reports, movies, and 3D animations can be readily linked to review notes. This paper describes three multimedia feed-back systems that Sandia National Laboratories has developed to tap that potential. Each system allows people to make context-sensitive comments about specific web content and electronically ties the comments back to the web content being referenced. The fuel system ties comments to specific web pages, the second system ties the comments to specific frames of digital movies, and the third ties the comments to specific times and viewpoints within 3D animations. In addition to the technologies, this paper describes how they are being used to support intelligent machine systems design at Sandia.

  3. Disrupting vagal feedback affects birdsong motor control

    PubMed Central

    Méndez, Jorge M.; Dall'Asén, Analía G.; Goller, Franz

    2010-01-01

    Coordination of different motor systems for sound production involves the use of feedback mechanisms. Song production in oscines is a well-established animal model for studying learned vocal behavior. Whereas the online use of auditory feedback has been studied in the songbird model, very little is known about the role of other feedback mechanisms. Auditory feedback is required for the maintenance of stereotyped adult song. In addition, the use of somatosensory feedback to maintain pressure during song has been demonstrated with experimentally induced fluctuations in air sac pressure. Feedback information mediating this response is thought to be routed to the central nervous system via afferent fibers of the vagus nerve. Here, we tested the effects of unilateral vagotomy on the peripheral motor patterns of song production and the acoustic features. Unilateral vagotomy caused a variety of disruptions and alterations to the respiratory pattern of song, some of which affected the acoustic structure of vocalizations. These changes were most pronounced a few days after nerve resection and varied between individuals. In the most extreme cases, the motor gestures of respiration were so severely disrupted that individual song syllables or the song motif were atypically terminated. Acoustic changes also suggest altered use of the two sound generators and upper vocal tract filtering, indicating that the disruption of vagal feedback caused changes to the motor program of all motor systems involved in song production and modification. This evidence for the use of vagal feedback by the song system with disruption of song during the first days after nerve cut provides a contrast to the longer-term effects of auditory feedback disruption. It suggests a significant role for somatosensory feedback that differs from that of auditory feedback. PMID:21113000

  4. Control and diagnostic uses of feedback

    SciTech Connect

    Sen, A. K.

    2000-05-01

    Recent results on multimode feedback control of magnetohydrodynamic (MHD) modes and a variety of diagnostic uses of feedback are summarized. First, is the report on reduction and scaling of transport under feedback. By controlling the fluctuation amplitudes and consequently the transport via feedback, it is found that the scaling of the diffusion coefficient is linear with root-mean-square rms fluctuation level. The scaling appears not to agree with any generic theory. A variety of other diagnostic uses of feedback have been developed. The primary goal is an experimental methodology for the determination of dynamic models of plasma turbulence, both for better transport understanding and more credible feedback controller designs. A specific motivation is to search for a low-order dynamic model, suitable for the convenient study of both transport and feedback. First, the time series analysis method is used for the determination of chaotic attractor dimension of plasma fluctuations. For ExB rotational flute modes it is found to be close to three, indicating that a low-order dynamic model may be adequate for transport prediction and feedback controller design. Second, a new method for direct experimental determination of nonlinear dynamical models of plasma turbulence using feedback has been developed. Specifically, the process begins with a standard three-wave coupling model and introduces a variable feedback gain. The power spectrum, delayed power spectrum, and bispectrum of fluctuations are then experimentally obtained. By varying the feedback gain continuously, an arbitrary number of numerical equations for a fixed number of unknowns can be generated. Their numerical solution yields the linear dispersion, as well as nonlinear coupling coefficients. This method has been successfully applied for ExB rotationally driven flute modes. (c) 2000 American Institute of Physics.

  5. Control and diagnostic uses of feedback

    NASA Astrophysics Data System (ADS)

    Sen, A. K.

    2000-05-01

    Recent results on multimode feedback control of magnetohydrodynamic (MHD) modes and a variety of diagnostic uses of feedback are summarized. First, is the report on reduction and scaling of transport under feedback. By controlling the fluctuation amplitudes and consequently the transport via feedback, it is found that the scaling of the diffusion coefficient is linear with root-mean-square rms fluctuation level. The scaling appears not to agree with any generic theory. A variety of other diagnostic uses of feedback have been developed. The primary goal is an experimental methodology for the determination of dynamic models of plasma turbulence, both for better transport understanding and more credible feedback controller designs. A specific motivation is to search for a low-order dynamic model, suitable for the convenient study of both transport and feedback. First, the time series analysis method is used for the determination of chaotic attractor dimension of plasma fluctuations. For E×B rotational flute modes it is found to be close to three, indicating that a low-order dynamic model may be adequate for transport prediction and feedback controller design. Second, a new method for direct experimental determination of nonlinear dynamical models of plasma turbulence using feedback has been developed. Specifically, the process begins with a standard three-wave coupling model and introduces a variable feedback gain. The power spectrum, delayed power spectrum, and bispectrum of fluctuations are then experimentally obtained. By varying the feedback gain continuously, an arbitrary number of numerical equations for a fixed number of unknowns can be generated. Their numerical solution yields the linear dispersion, as well as nonlinear coupling coefficients. This method has been successfully applied for E×B rotationally driven flute modes.

  6. Miocene ridge impingement and the spawning of secondary ridges off Oregon, Washington and British Columbia

    NASA Astrophysics Data System (ADS)

    Farrar, Edward; Dixon, John M.

    1980-11-01

    The East Pacific Rise is the only extant portion of the South Pacific Spreading Center, which began to impinge on the North American plate margin ~30 Ma ago. The North Pacific Spreading Center, offset ~1500 km to the west on the Mendocino transform fault, remained active until ~9 Ma ago when it, too, impinged on the trench off the Oregon—Washington margin. The zones of mantle upwelling associated with the spreading centers have since migrated inland to their present sites beneath the Cascade and Garibaldi volcanic chains and the Rio Grande Rift, maintaining the ~1500 km offset that they have had since the Early Tertiary. Impingement of the North Pacific Spreading Center on the trench at anomaly 5 time juxtaposed the Pacific and American plates and the continuing relative motion between these plates across the north—south boundary has been accommodated by secondary spreading at the Gorda—Juan de Fuca—Explorer ridge system. These obliquely spreading ridges, fed by lateral mantle flow originating at the zone of mantle upwelling beneath the Cascade belt, are migrating away from the North American coast at half the Pacific—America velocity, and no subduction is occurring along the continental margin, the Juan de Fuca sea floor being an integral part of the American plate. This scenario is consistent with the fact that the sea floor along the continental margin has the same age as that which bears the last north—south anomaly on the Pacific plate (anomaly 5) preceding initiation of spreading at the Juan de Fuca and Explorer ridges (a fortuitous coincidence in models involving continued subduction of the Juan de Fuca sea floor). This model implies that the rate of motion between the Pacific and American plates is 8 cm/a. The Blanco fracture zone formed as a transform fault at the south end of the Juan de Fuca ridge and was initially collinear with the North American margin south of Cape Mendocino. The North Pacific Spreading Center impinged on this portion of

  7. Feedback Alignment: Effective and Ineffective Links between Tutors' and Students' Understanding of Coursework Feedback

    ERIC Educational Resources Information Center

    Orsmond, Paul; Merry, Stephen

    2011-01-01

    Tutors' intentions when providing feedback may not be accurately perceived and acted on by students. In this study, 19 biological sciences students and six tutors were interviewed concerning the tutor's intentions when providing specific feedback and the students' perceptions and usage of that feedback. A phenomenological approach was used to…

  8. Closing the Feedback Loop? Iterative Feedback between Tutor and Student in Coursework Assessments

    ERIC Educational Resources Information Center

    Barker, Martin; Pinard, Michelle

    2014-01-01

    We evaluate the case for using feedback iteratively, to improve student engagement and learning. In this model, students were invited to respond to tutor feedback with students' own responses. Among the three courses/modules (three tutors) studied, differences in feedback styles were evident from: (a) thematic analysis of tutor comments and,…

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

    ERIC Educational Resources Information Center

    So, Yongjoon; Lee, Kyehoon; Oah, Shezeen

    2013-01-01

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

  10. "Are You Listening Please?" The Advantages of Electronic Audio Feedback Compared to Written Feedback

    ERIC Educational Resources Information Center

    Lunt, Tom; Curran, John

    2010-01-01

    Feedback on students' work is, probably, one of the most important aspects of learning, yet students' report, according to the National Union of Students (NUS) Survey of 2008, unhappiness with the feedback process. Students were unhappy with the quality, detail and timing of feedback. This paper examines the benefits of using audio, as opposed to…

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

    ERIC Educational Resources Information Center

    Raemdonck, Isabel; Strijbos, Jan-Willem

    2013-01-01

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

  12. ENVIRONMENTAL BASELINE SURVEY REPORT FOR WEST BLACK OAK RIDGE, EAST BLACK OAK RIDGE, MCKINNEY RIDGE, WEST PINE RIDGE, AND PARCEL 21D IN THE VICINITY OF THE EAST TENNESSEE TECHNOLOGY PARK, OAK RIDGE, TENNESSEE

    SciTech Connect

    David A. King

    2012-11-29

    This environmental baseline survey (EBS) report documents the baseline environmental conditions of five land parcels located near the U.S. Department of Energy’s (DOE’s) East Tennessee Technology Park (ETTP), including West Black Oak Ridge, East Black Oak Ridge, McKinney Ridge, West Pine Ridge, and Parcel 21d. The goal is to obtain all media no-further-investigation (NFI) determinations for the subject parcels considering existing soils. To augment the existing soils-only NFI determinations, samples of groundwater, surface water, soil, and sediment were collected to support all media NFI decisions. The only updates presented here are those that were made after the original issuance of the NFI documents. In the subject parcel where the soils NFI determination was not completed for approval (Parcel 21d), the full process has been performed to address the soils as well. Preparation of this report included the detailed search of federal government records, title documents, aerial photos that may reflect prior uses, and visual inspections of the property and adjacent properties. Interviews with current employees involved in, or familiar with, operations on the real property were also conducted to identify any areas on the property where hazardous substances and petroleum products, or their derivatives, and acutely hazardous wastes may have been released or disposed. In addition, a search was made of reasonably obtainable federal, state, and local government records of each adjacent facility where there has been a release of any hazardous substance or any petroleum product or their derivatives, including aviation fuel and motor oil, and which is likely to cause or contribute to a release of any hazardous substance or any petroleum product or its derivatives, including aviation fuel or motor oil, on the real property. A radiological survey and soil/sediment sampling was conducted to assess baseline conditions of Parcel 21d that were not addressed by the soils-only NFI

  13. Hydrodynamic role of longitudinal ridges in a leatherback turtle swimming

    NASA Astrophysics Data System (ADS)

    Bang, Kyeongtae; Kim, Jooha; Lee, Sang-Im; Choi, Haecheon

    2015-11-01

    The leatherback sea turtle (Dermochelys coriacea), the fastest swimmer and the deepest diver among marine turtles, has five longitudinal ridges on its carapace. These ridges are the most remarkable morphological features distinguished from other marine turtles. To investigate the hydrodynamic role of these ridges in the leatherback turtle swimming, we model a carapace with and without ridges by using three dimensional surface data of a stuffed leatherback turtle in the National Science Museum, Korea. The experiment is conducted in a wind tunnel in the ranges of the real leatherback turtle's Reynolds number (Re) and angle of attack (α). The longitudinal ridges function differently according to the flow condition (i.e. Re and α). At low Re and negative α that represent the swimming condition of hatchlings and juveniles, the ridges significantly decrease the drag by generating streamwise vortices and delaying the main separation. On the other hand, at high Re and positive α that represent the swimming condition of adults, the ridges suppress the laminar separation bubble near the front part by generating streamwise vortices and enhance the lift and lift-to-drag ratio. Supported by the NRF program (2011-0028032).

  14. 10 CFR 850.40 - Performance feedback.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 4 2012-01-01 2012-01-01 false Performance feedback. 850.40 Section 850.40 Energy DEPARTMENT OF ENERGY CHRONIC BERYLLIUM DISEASE PREVENTION PROGRAM Specific Program Requirements § 850.40 Performance feedback. (a) The responsible employer must conduct periodic analyses and assessments...

  15. 10 CFR 850.40 - Performance feedback.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Performance feedback. 850.40 Section 850.40 Energy DEPARTMENT OF ENERGY CHRONIC BERYLLIUM DISEASE PREVENTION PROGRAM Specific Program Requirements § 850.40 Performance feedback. (a) The responsible employer must conduct periodic analyses and assessments...

  16. 10 CFR 850.40 - Performance feedback.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 4 2014-01-01 2014-01-01 false Performance feedback. 850.40 Section 850.40 Energy DEPARTMENT OF ENERGY CHRONIC BERYLLIUM DISEASE PREVENTION PROGRAM Specific Program Requirements § 850.40 Performance feedback. (a) The responsible employer must conduct periodic analyses and assessments...

  17. 10 CFR 850.40 - Performance feedback.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 4 2013-01-01 2013-01-01 false Performance feedback. 850.40 Section 850.40 Energy DEPARTMENT OF ENERGY CHRONIC BERYLLIUM DISEASE PREVENTION PROGRAM Specific Program Requirements § 850.40 Performance feedback. (a) The responsible employer must conduct periodic analyses and assessments...

  18. 10 CFR 850.40 - Performance feedback.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Performance feedback. 850.40 Section 850.40 Energy DEPARTMENT OF ENERGY CHRONIC BERYLLIUM DISEASE PREVENTION PROGRAM Specific Program Requirements § 850.40 Performance feedback. (a) The responsible employer must conduct periodic analyses and assessments...

  19. Feedback Processes in Multimedia Language Learning Software

    ERIC Educational Resources Information Center

    Kartal, Erdogan

    2010-01-01

    Feedback has been one of the important elements of learning and teaching theories and still pervades the literature and instructional models, especially computer and web-based ones. However, the mechanisms about feedback dominating the fundamentals of all the instructional models designed for self-learning have changed considerably with the…

  20. Teaching Writing Using Peer Feedback Checklists.

    ERIC Educational Resources Information Center

    Furneaux, Clare

    2002-01-01

    Discusses incorporation of peer feedback check lists in the English-as-a-Second-Language writing classroom. Highlights different types of check lists, including generic and text-specific, and how to use check lists for peer feedback. (Author/VWL)

  1. Optical feedback structures and methods of making

    DOEpatents

    Snee, Preston T; Chan, Yin Thai; Nocera, Daniel G; Bawendi, Moungi G

    2014-11-18

    An optical resonator can include an optical feedback structure disposed on a substrate, and a composite including a matrix including a chromophore. The composite disposed on the substrate and in optical communication with the optical feedback structure. The chromophore can be a semiconductor nanocrystal. The resonator can provide laser emission when excited.

  2. Corrective Feedback and Learner Uptake in CALL

    ERIC Educational Resources Information Center

    Heift, Trude

    2004-01-01

    This paper describes a study in which we investigated the effects of corrective feedback on learner uptake in CALL. Learner uptake is here defined as learner responses to corrective feedback in which, in case of an error, students attempt to correct their mistake(s). 177 students from three Canadian universities participated in the study during…

  3. Does Automated Feedback Improve Writing Quality?

    ERIC Educational Resources Information Center

    Wilson, Joshua; Olinghouse, Natalie G.; Andrada, Gilbert N.

    2014-01-01

    The current study examines data from students in grades 4-8 who participated in a statewide computer-based benchmark writing assessment that featured automated essay scoring and automated feedback. We examined whether the use of automated feedback was associated with gains in writing quality across revisions to an essay, and with transfer effects…

  4. The Tuckman Teacher Feedback Form (TTFF).

    ERIC Educational Resources Information Center

    Tuckman, Bruce Wayne

    Originally designed to provide teachers with feedback and also used as a quantitative tool for specifying teacher behavior consistent with a psychological model of teaching described by Tuckman (1974), the Tuckman Teacher Feedback Form (TTFF) is a 28-item semantic differential which generates four scores in the areas of creativity, dynamism…

  5. Feedback for Teachers: Focused, Specific, and Constructive

    ERIC Educational Resources Information Center

    Westerberg, Tim R.

    2013-01-01

    Across the country, there is a renewed emphasis on using teacher evaluation not only to rate teachers but also to give them formative feedback that will help them improve classroom instruction. Recent research shows that applying the strategies that teachers use to give students effective feedback to the teacher evaluation process produces…

  6. Computer-Generated Feedback on Student Writing

    ERIC Educational Resources Information Center

    Ware, Paige

    2011-01-01

    A distinction must be made between "computer-generated scoring" and "computer-generated feedback". Computer-generated scoring refers to the provision of automated scores derived from mathematical models built on organizational, syntactic, and mechanical aspects of writing. In contrast, computer-generated feedback, the focus of this article, refers…

  7. Recurrent Feedback Loops in Associative Learning.

    PubMed

    Person, Abigail L; Khodakhah, Kamran

    2016-02-01

    In this issue of Neuron, Gao et al. (2016) report on a little-studied feedback pathway from the cerebellar nuclei back to the cerebellar cortex. They find that it contributes to associative conditioning and execution of learned movements, highlighting a role for local feedback loops in the brain. PMID:26844826

  8. Enhancing Students' Learning: Instant Feedback Cards

    ERIC Educational Resources Information Center

    Mohrweis, Lawrence C.; Shinham, Kathe M.

    2015-01-01

    This study illustrates an active learning approach using instant feedback cards in the first course in accounting. The objectives of this study are to (1) describe instant feedback cards and (2) show how this tool, when used in an active learning environment, can enhance learning. We examined whether students exposed to immediate feedback…

  9. Immediate Feedback to Students and Student Learning

    ERIC Educational Resources Information Center

    Walker, Karen

    2011-01-01

    A study reported by The National Center for Fair and Open Testing (Black & William, 2007) found that low achievers do particularly well when provided high quality feedback about their work. The type of feedback, as well as the information provided to students about their assignments, can positively impact student learning. Providing students with…

  10. Supporting Second Language Writing Using Multimodal Feedback

    ERIC Educational Resources Information Center

    Elola, Idoia; Oskoz, Ana

    2016-01-01

    The educational use of computer-based feedback in the classroom is becoming widespread. However, less is known about (1) the extent to which tools influence how instructors provide written and oral comments, and (2) whether receiving oral or written feedback influences the nature of learners' revisions. This case study, which expands existing…

  11. Feedbacks in human-landscape systems.

    PubMed

    Chin, Anne; Florsheim, Joan L; Wohl, Ellen; Collins, Brian D

    2014-01-01

    This article identifies key questions and challenges for geomorphologists in investigating coupled feedbacks in human-landscape systems. While feedbacks occur in the absence of human influences, they are also altered by human activity. Feedbacks are a key element to understanding human-influenced geomorphic systems in ways that extend our traditional approach of considering humans as unidirectional drivers of change. Feedbacks have been increasingly identified in Earth-environmental systems, with studies of coupled human-natural systems emphasizing ecological phenomena in producing emerging concepts for social-ecological systems. Enormous gaps or uncertainties in knowledge remain with respect to understanding impact-feedback loops within geomorphic systems with significant human alterations, where the impacted geomorphic systems in turn affect humans. Geomorphology should play an important role in public policy by identifying the many diffuse and subtle feedbacks of both local- and global-scale processes. This role is urgent, while time may still be available to mitigate the impacts that limit the sustainability of human societies. Challenges for geomorphology include identification of the often weak feedbacks that occur over varied time and space scales ranging from geologic time to single isolated events and very short time periods, the lack of available data linking impact with response, the identification of multiple thresholds that trigger feedback mechanisms, the varied tools and metrics needed to represent both physical and human processes, and the need to collaborate with social scientists with expertise in the human causes of geomorphic change, as well as the human responses to such change.

  12. Feedbacks in Human-Landscape Systems

    NASA Astrophysics Data System (ADS)

    Chin, Anne; Florsheim, Joan L.; Wohl, Ellen; Collins, Brian D.

    2014-01-01

    This article identifies key questions and challenges for geomorphologists in investigating coupled feedbacks in human-landscape systems. While feedbacks occur in the absence of human influences, they are also altered by human activity. Feedbacks are a key element to understanding human-influenced geomorphic systems in ways that extend our traditional approach of considering humans as unidirectional drivers of change. Feedbacks have been increasingly identified in Earth-environmental systems, with studies of coupled human-natural systems emphasizing ecological phenomena in producing emerging concepts for social-ecological systems. Enormous gaps or uncertainties in knowledge remain with respect to understanding impact-feedback loops within geomorphic systems with significant human alterations, where the impacted geomorphic systems in turn affect humans. Geomorphology should play an important role in public policy by identifying the many diffuse and subtle feedbacks of both local- and global-scale processes. This role is urgent, while time may still be available to mitigate the impacts that limit the sustainability of human societies. Challenges for geomorphology include identification of the often weak feedbacks that occur over varied time and space scales ranging from geologic time to single isolated events and very short time periods, the lack of available data linking impact with response, the identification of multiple thresholds that trigger feedback mechanisms, the varied tools and metrics needed to represent both physical and human processes, and the need to collaborate with social scientists with expertise in the human causes of geomorphic change, as well as the human responses to such change.

  13. Teacher Cognition in Corrective Feedback in Japan

    ERIC Educational Resources Information Center

    Mori, Reiko

    2011-01-01

    Based on qualitative data, the current study explored how the knowledge and beliefs of two EFL professionals shaped their corrective feedback practices. The two teachers teaching in Japan had in common two main agendas that they kept in mind as they provided or opted not to provide corrective feedback. They aimed to teach the language and to…

  14. Peer Feedback on Language Form in Telecollaboration

    ERIC Educational Resources Information Center

    Ware, Paige D.; O'Dowd, Robert

    2008-01-01

    We performed a two-phase, year-long research project that explored the impact of peer feedback on language development. We investigated specifically how and when post-secondary learners of English and Spanish provide corrective feedback on their partners' use of the target language in weekly asynchronous discussions by assigning them to one of two…

  15. Constructive feedback in organizational team-building.

    PubMed

    Brodsky, S L; Runcie, D; Lichtenstein, B

    1996-01-01

    Ways constructive feedback can help an organization achieve and maintain a competitive advantage within and without the workplace is the topic of this chapter. An approach called 360 feedback is detailed, by which an employee is rated by workers at various levels in the organizational hierarchy instead of by a single supervisor.

  16. Providing Effective Feedback to EFL Student Teachers

    ERIC Educational Resources Information Center

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

    2013-01-01

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

  17. Student Views on the Value of Feedback

    ERIC Educational Resources Information Center

    Marie, Jenny A.

    2016-01-01

    This paper investigates the value that a sample of students placed on feedback, what they valued it for and the conditions that affected this value judgement. I show that not all students value feedback particularly highly, especially when considered in relation to other factors in their education and when considered for its intrinsic value as…

  18. Preregulator feedback circuit utilizes Light Actuated Switch

    NASA Technical Reports Server (NTRS)

    Hayser, T. P.

    1966-01-01

    Preregulator feedback circuit employing a Light Actuated Switch /LAS/ provides a simple and efficient feedback device in a power supply preregulator which maintains dc isolation between input and output grounds. The LAS consists of a diode PN junction infrared source close to, but electrically isolated from, a photodetector.

  19. Feedback after Good Trials Enhances Learning

    ERIC Educational Resources Information Center

    Chiviacowsky, Suzete; Wulf, Gabriele

    2007-01-01

    Recent studies (Chiviacowsky & Wulf, 2002, 2005) have shown that learners prefer to receive feedback after they believe they had a "good" rather than "poor" trial. The present study followed up on this finding and examined whether learning would benefit if individuals received feedback after good relative to poor trials. Participants practiced a…

  20. Graphical Understanding of Simple Feedback Systems.

    ERIC Educational Resources Information Center

    Janvier, Claude; Garancon, Maurice

    1989-01-01

    Shows that graphs can reveal much about feedback systems that formula conceal, especially as microcomputers can provide complex graphs presented as animations and allow students to interact easily with them. Describes feedback systems, evolution of the system, and phase diagram. (YP)

  1. Technologies for Learner-Centered Feedback

    ERIC Educational Resources Information Center

    Costello, Jane; Crane, Daph

    2013-01-01

    As the number, type, and use of technologies to support learning increases, so do the opportunities for using these technologies for feedback. Learner-centered feedback is a core to the teaching-learning process. It is related to assessment in describing how learners perform in their learning, their gain in knowledge, skills, and attitudes.…

  2. Electrometer preamplifier has drift correction feedback

    NASA Technical Reports Server (NTRS)

    Labarthe, L. C.

    1965-01-01

    Negative feedback circuit corrects output drift in an electrometer. The negative feedback is used in the no signal state to maintain the output level at zero reference. Drift voltage storage in the signal on state is also used to provide a drift-free readout.

  3. Characteristics of Hydrothermal Mineralization in Ultraslow Spreading Ridges

    NASA Astrophysics Data System (ADS)

    Zhou, H.; Yang, Q.; Ji, F.; Dick, H. J.

    2014-12-01

    Hydrothermal activity is a major component of the processes that shape the composition and structure of the ocean crust, providing a major pathway for the exchange of heat and elements between the Earth's crust and oceans, and a locus for intense biological activity on the seafloor and underlying crust. In other hand, the structure and composition of hydrothermal systems are the result of complex interactions between heat sources, fluids, wall rocks, tectonic controls and even biological processes. Ultraslow spreading ridges, including the Southwest Indian Ridge, the Gakkel Ridge, are most remarkable end member in plate-boundary structures (Dick et al., 2003), featured with extensive tectonic amagmatic spreading and frequent exposure of peridotite and gabbro. With intensive surveys in last decades, it is suggested that ultraslow ridges are several times more effective than faster-spreading ridges in sustaining hydrothermal activities. This increased efficiency could attributed to deep mining of heat and even exothermic serpentinisation (Baker et al., 2004). Distinct from in faster spreading ridges, one characteristics of hydrothermal mineralization on seafloor in ultraslow spreading ridges, including the active Dragon Flag hydrothermal field at 49.6 degree of the Southwest Indian Ridge, is abundant and pervasive distribution of lower temperature precipitated minerals ( such as Fe-silica or silica, Mn (Fe) oxides, sepiolite, pyrite, marcasite etc. ) in hydrothermal fields. Structures formed by lower temperature activities in active and dead hydrothermal fields are also obviously. High temperature precipitated minerals such as chalcopyrite etc. are rare or very limited in hydrothermal chimneys. Distribution of diverse low temperature hydrothermal activities is consistence with the deep heating mechanisms and hydrothermal circulations in the complex background of ultraslow spreading tectonics. Meanwhile, deeper and larger mineralization at certain locations along the

  4. Multiple linear regression with correlations among the predictor variables. Theory and computer algorithm ridge (FORTRAN 77)

    NASA Astrophysics Data System (ADS)

    van Gaans, P. F. M.; Vriend, S. P.

    Application of ridge regression in geoscience usually is a more appropriate technique than ordinary least-squares regression, especially in the situation of highly intercorrelated predictor variables. A FORTRAN 77 program RIDGE for ridged multiple linear regression is presented. The theory of linear regression and ridge regression is treated, to allow for a careful interpretation of the results and to understand the structure of the program. The program gives various parameters to evaluate the extent of multicollinearity within a given regression problem, such as the correlation matrix, multiple correlations among the predictors, variance inflation factors, eigenvalues, condition number, and the determinant of the predictors correlation matrix. The best method for the optimum choice of the ridge parameter with ridge regression has not been established yet. Estimates of the ridge bias, ridged variance inflation factors, estimates, and norms for the ridge parameter therefore are given as output by RIDGE and should complement inspection of the ridge traces. Application within the earth sciences is discussed.

  5. SRTM Stereo Pair: Wheeler Ridge, California

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Wheeler Ridge and vicinity, California, is a site of major tectonic activity, both historically and over recent geologic time. The epicenter of the 7.5 magnitude Kern County earthquake occurred here on July 21,1952, and numerous geologic and topographic features indicate rapid geologic processes. The ridge itself (upper-right center) is a geologic fold that is growing out of the southern San Joaquin Valley. A prominent 'wind gap,' now used for passage of the California aquaduct (with the aid of a pumping station), is evidence that the ridge grew faster than tranversing streams could erode down. Nearby abrupt and/or landslid mountain fronts similarly indicate a vigorous tectonic setting here, just north of the San Andreas fault. The Interstate 5 freeway can be seen crossing agricultural fields on the right and entering the very rugged and steep Grapevine Canyon toward the bottom.

    This stereoscopic image was generated by draping a Landsat satellite image over a preliminary Shuttle Radar Topography Mission (SRTM) elevation model. Two differing perspectives were then calculated, one for each eye. They can be seen in 3-D by viewing the left image with the right eye and the right image with the left eye (cross-eyed viewing), or by downloading and printing the image pair and viewing them with a stereoscope. When stereoscopically merged, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data matches the 30-meter resolution of most Landsat images and will substantially help in analyses of the large and growing Landsat image archive.

    The elevation data used in this image was acquired by SRTM aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle

  6. Variables affecting athletes' retention of coaches' feedback.

    PubMed

    Januário, Nuno M S; Rosado, Antonio F; Mesquita, Isabel

    2013-10-01

    Athletes' retention of information conveyed in coaches' feedback during training was examined, considering the nature of the information transmitted by each coach (extensions, total number of ideas transmitted, and total number of repeated ideas), athletes' characteristics, (ages, genders, school levels, and practice levels), and athletes' perceptions (relevance and acceptance of coaches' information, task motivational levels, and athletes' attention levels). Participants were 193 athletes (79 boys, 114 girls; 9 to 13 years of age) and 6 coaches. Feedback was both audio and video recorded and all athletes were interviewed. All coaches' feedback and athletes' recollections were subjected to content analysis. Information was completely retained in 31.60% of feedback episodes. Athletes' mean per-episode information retention was 63.0%. Three variables appeared to b e predictiveathletes' retention: athletes' practice levels (p = -.25), attention to coaches' provision of feedback (P = .17), and the number of different ideas transmitted by each coach (P = -.90).

  7. Feedbacks and landscape-level vegetation dynamics.

    PubMed

    Bowman, David M J S; Perry, George L W; Marston, J B

    2015-05-01

    Alternative stable-state theory (ASS) is widely accepted as explaining landscape-level vegetation dynamics, such as switches between forest and grassland. This theory argues that webs of feedbacks stabilise vegetation composition and structure, and that abrupt state shifts can occur if stabilising feedbacks are weakened. However, it is difficult to identify stabilising feedback loops and the disturbance thresholds beyond which state changes occur. Here, we argue that doing this requires a synthetic approach blending observation, experimentation, simulation, conceptual models, and narratives. Using forest boundaries and large mammal extinctions, we illustrate how a multifaceted research program can advance understanding of feedback-driven ecosystem change. Our integrative approach has applicability to other complex macroecological systems controlled by numerous feedbacks where controlled experimentation is impossible.

  8. Enhanced Negative Feedback Responses in Remitted Depression

    PubMed Central

    Santesso, Diane L.; Steele, Katherine T.; Bogdan, Ryan; Holmes, Avram J.; Deveney, Christen M.; Meites, Tiffany M.; Pizzagalli, Diego A.

    2011-01-01

    Major depressive disorder (MDD) is characterized by hypersensitivity to negative feedback that might involve frontocingulate dysfunction. MDD subjects exhibit enhanced electrophysiological responses to negative internal (errors) and external (feedback) cues. Whether this dysfunction extends to remitted depressed (RD) subjects with a history of MDD is currently unknown. To address this issue, we examined the feedback-related negativity (FRN) in RD and control subjects using a probabilistic punishment learning task. Despite equivalent behavioral performance, RD subjects showed larger FRNs to negative feedback relative to controls; group differences remained after accounting for residual anxiety and depressive symptoms. The present findings suggest that abnormal responses to negative feedback extend to samples at increased risk for depressive episodes in the absence of current symptoms. PMID:18580576

  9. Prediction feedback in intelligent traffic systems

    NASA Astrophysics Data System (ADS)

    Dong, Chuan-Fei; Ma, Xu; Wang, Guan-Wen; Sun, Xiao-Yan; Wang, Bing-Hong

    2009-11-01

    The optimal information feedback has a significant effect on many socioeconomic systems like stock market and traffic systems aiming to make full use of resources. In this paper, we studied dynamics of traffic flow with real-time information provided and the influence of a feedback strategy named prediction feedback strategy is introduced, based on a two-route scenario in which dynamic information can be generated and displayed on the board to guide road users to make a choice. Our model incorporates the effects of adaptability into the cellular automaton models of traffic flow and simulation results adopting this optimal information feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other three information feedback strategies, i.e., vehicle number and flux.

  10. Minimum Requirements for Feedback Enhanced Force Sensing

    NASA Astrophysics Data System (ADS)

    Harris, Glen I.; McAuslan, David L.; Stace, Thomas M.; Doherty, Andrew C.; Bowen, Warwick P.

    2013-09-01

    The problem of estimating an unknown force driving a linear oscillator is revisited. When using linear measurement, feedback is often cited as a mechanism to enhance bandwidth, sensitivity or resolution. We show that as long as the oscillator dynamics are known, there exists a real-time estimation strategy that reproduces the same measurement record as any arbitrary feedback protocol. Consequently some form of nonlinearity is required to gain any advantage beyond estimation alone. This result holds true in both quantum and classical systems, with nonstationary forces and feedback, and in the general case of non-Gaussian and correlated noise. Recently, feedback enhanced incoherent force resolution has been demonstrated [E. Gavartin, P. Verlot, and T. J. Kippenberg, Nat. Nano. 7, 509 (2012)], with the enhancement attributed to a feedback induced modification of the mechanical susceptibility. As a proof-of-principle, we experimentally reproduce this result through straightforward filtering.

  11. Hollow dentures: treatment option for atrophic ridges. a clinical report.

    PubMed

    Caculo, Shweta Pandurang; Aras, Meena Ajay; Chitre, Vidya

    2013-04-01

    Severely atrophic ridges provide decreased retention, support, and stability and pose a clinical challenge to the success of complete denture prostheses. Extreme ridge resorption also increases the interridge distance. Restoration of the vertical dimension and esthetics thus demands increased height of the prosthesis and in turn leads to an increase in prosthesis weight. Reducing the weight of the denture enhances stability and retention and reduces further resorption of the jaw, thereby favoring the prognosis of the denture. This report describes the rehabilitation of an edentulous patient with resorbed maxillary and mandibular ridges and an increased interridge distance using simplified techniques of fabricating hollow dentures.

  12. Migration of mid-ocean-ridge volcanic segments

    USGS Publications Warehouse

    Schouten, Hans; Dick, H.J.B.; Klitgord, Kim D.

    1987-01-01

    The propagation of small-offset volcanic spreading-centre segments along mid-ocean ridge crests may reflect absolute motion of the plate boundary relative to the underlying mesospheric frame. Such a relationship could be caused by a purely vertical flow of the mantle under spreading centres and would have value in constraining past plate motions from non-transform trends generated during along-ridge propagation and in linking the major-element variability of oceanic crust and upper mantle to the bulk composition and temperatures of mantle ascending under mid-ocean ridges. ?? 1987 Nature Publishing Group.

  13. The Oak Ridge Refrigerant Management Program

    NASA Technical Reports Server (NTRS)

    Kevil, Thomas H.

    1995-01-01

    For many years, chlorofluorocarbons (CFC's) have been used by the Department of Energy's (DOE) Oak Ridge Y-12 Plant in air conditioning and process refrigeration systems. However, Title 6 of the Clean Air Act Amendments (CAAA) and Executive Order 12843 (Procurement Requirements and Policies for Federal Agencies for Ozone Depleting Substances) signed by President Clinton require, as policy, that all federal agencies maximize their use of safe, alternate refrigerants and minimize, where economically practical, the use of Class 1 refrigerants. Unfortunately, many government facilities and industrial plants have no plan or strategy in place to make this changeover, even though their air conditioning and process refrigeration equipment may not be sustainable after CFC production ends December 31, 1995. The Y-12 Plant in Oak Ridge, Tennessee, has taken an aggressive approach to complying with the CAAA and is working with private industry and other government agencies to solve tough manufacturing and application problems associated with CFC and hydrochlorofluorocarbon (HCFC) alternatives. Y-12 was the first DOE Defense Program (DP) facility to develop a long-range Stratospheric Ozone Protection Plan for refrigerant management for compliance with the CAAA. It was also the first DOE DP facility to complete detailed engineering studies on retrofitting and replacing all air conditioning and process refrigeration equipment to enable operation with alternate refrigerants. The management plan and engineering studies are models for use by other government agencies, manufacturing plants, and private industry. This presentation identifies some of the hidden pitfalls to be encountered in the accelerated phaseout schedule of CFC's and explains how to overcome and prevent these problems. In addition, it outlines the general issues that must be considered when addressing the phase-out of ozone depleting substances and gives some 'lessons learned' by Y-12 from its Refrigerant Management

  14. Artificial proprioceptive feedback for myoelectric control.

    PubMed

    Pistohl, Tobias; Joshi, Deepak; Ganesh, Gowrishankar; Jackson, Andrew; Nazarpour, Kianoush

    2015-05-01

    The typical control of myoelectric interfaces, whether in laboratory settings or real-life prosthetic applications, largely relies on visual feedback because proprioceptive signals from the controlling muscles are either not available or very noisy. We conducted a set of experiments to test whether artificial proprioceptive feedback, delivered noninvasively to another limb, can improve control of a two-dimensional myoelectrically-controlled computer interface. In these experiments, participants were required to reach a target with a visual cursor that was controlled by electromyogram signals recorded from muscles of the left hand, while they were provided with an additional proprioceptive feedback on their right arm by moving it with a robotic manipulandum. Provision of additional artificial proprioceptive feedback improved the angular accuracy of their movements when compared to using visual feedback alone but did not increase the overall accuracy quantified with the average distance between the cursor and the target. The advantages conferred by proprioception were present only when the proprioceptive feedback had similar orientation to the visual feedback in the task space and not when it was mirrored, demonstrating the importance of congruency in feedback modalities for multi-sensory integration. Our results reveal the ability of the human motor system to learn new inter-limb sensory-motor associations; the motor system can utilize task-related sensory feedback, even when it is available on a limb distinct from the one being actuated. In addition, the proposed task structure provides a flexible test paradigm by which the effectiveness of various sensory feedback and multi-sensory integration for myoelectric prosthesis control can be evaluated.

  15. Students’ perceptions on feedback module in pharmacology

    PubMed Central

    Patel, Varsha J.; Malhotra, Supriya D.; Rana, Devang A.

    2016-01-01

    Context: Feedback is an integral part of formative assessment though underutilized in medical education. The objective of this study was to review our feedback module through students’ perceptions. Methodology: We have developed a feedback module which is practiced by us for last 10 years for term ending examination that gives collective feedback to the whole class, followed by individual student-teacher interactions. Students were also exposed to 6–7 multiple choice questions (MCQs) based assessment during the course of pharmacology. Immediately after each MCQ test the answer keys is displayed along with an explanation. Two classes of students were requested to give their perceptions about the feedback by responding on Likert scale for the statements in the questionnaire. All the 206 students who volunteered for the study were enrolled in the study. Mann–Whitney test was used to calculate the difference in perceptions. Results: Of 278 students of two classes, 206 responded (74%). Students’ agreement varied from 93% to 98% for 5 items in the questionnaire for the feedback after term ending examinations. Perception of students attending one or more than one feedback session did not differ significantly. For MCQs, tests agreement was 91% to 98% for the 4 items. There was no significant difference between two classes in their perceptions regarding feedback practices (P < 0.05). Conclusion: Students gave a favorable opinion for our feedback module. In the medical colleges with a large number of students, this module is feasible for feedback in formative assessment in the form of written tests. PMID:27500170

  16. Feedback in Clinical Education, Part I: Characteristics of Feedback Provided by Approved Clinical Instructors

    PubMed Central

    Nottingham, Sara; Henning, Jolene

    2014-01-01

    Context Providing students with feedback is an important component of athletic training clinical education; however, little information is known about the feedback that Approved Clinical Instructors (ACIs; now known as preceptors) currently provide to athletic training students (ATSs). Objective To characterize the feedback provided by ACIs to ATSs during clinical education experiences. Design Qualitative study. Setting One National Collegiate Athletic Association Division I athletic training facility and 1 outpatient rehabilitation clinic that were clinical sites for 1 entry-level master's degree program accredited by the Commission on Accreditation of Athletic Training Education. Patients or Other Participants A total of 4 ACIs with various experience levels and 4 second-year ATSs. Data Collection and Analysis Extensive field observations were audio recorded, transcribed, and integrated with field notes for analysis. The constant comparative approach of open, axial, and selective coding was used to inductively analyze data and develop codes and categories. Member checking, triangulation, and peer debriefing were used to promote trustworthiness of the study. Results The ACIs gave 88 feedback statements in 45 hours and 10 minutes of observation. Characteristics of feedback categories included purpose, timing, specificity, content, form, and privacy. Conclusions Feedback that ACIs provided included several components that made each feedback exchange unique. The ACIs in our study provided feedback that is supported by the literature, suggesting that ACIs are using current recommendations for providing feedback. Feedback needs to be investigated across multiple athletic training education programs to gain more understanding of certain areas of feedback, including frequency, privacy, and form. PMID:24143902

  17. Modeling of hydroecological feedbacks predicts distinct classes of landscape pattern, process, and restoration potential in shallow aquatic ecosystems

    USGS Publications Warehouse

    Larsen, Laurel G.; Harvey, Judson W.

    2011-01-01

    In general, the stability of different wetland pattern types is most strongly related to factors controlling the erosion and deposition of sediment at vegetation patch edges, the magnitude of sediment redistribution by flow, patch elevation relative to water level, and the variability of erosion rates in vegetation patches with low flow-resistance. As we exemplify in our case-study of the Everglades ridge and slough landscape, feedback between flow and vegetation also causes hysteresis in landscape evolution trajectories that will affect the potential for landscape restoration. Namely, even if the hydrologic conditions that historically produced higher flows are restored, degraded portions of the ridge and slough landscape are unlikely to revert to their former patterning. As wetlands and floodplains worldwide become increasingly threatened by climate change and urbanization, the greater mechanistic understanding of landscape pattern and process that our analysis provides will improve our ability to forecast and manage the behavior of these ecosystems.

  18. Episodes of aleutian ridge explosive volcanism.

    PubMed

    Hein, J R; Scholl, D W; Miller, J

    1978-01-13

    Earlier workers have overlooked deep-sea bentonite beds when unraveling the Cenozoic volcanic history of an area. In the North Pacific, identification of Miocene and older volcanic episodes is possible only if both altered (bentonite) and unaltered ash beds are recognized. Our study, which includes bentonite beds, shows that volcanism on the Aleutian Ridge and Kamchatka Peninsula has been cyclic. Volcanic activity seems to have increased every 2.5 x 10(6) years for the past 10 x 10(6) years and every 5.0 x 10(6) years for the time span from 10 to 20 x 10(6) years ago. The middle and late Miocene and the Quaternary were times of greatly increased volcanic activity in the North Pacific and elsewhere around the Pacific Basin. The apparent absence of a volcanic record before the late Miocene at Deep Sea Drilling Project site 192 is the result not of plate motion, as suggested by Stewart and by Ninkovich and Donn, but rather of the diagenesis of ash layers. Major, apparently global volcanic episodes occurred at least twice in the last 20 x 10(6) years. Yet, only one major glacial epoch (the Pleistocene) has occurred. Therefore, even though glaciation coincided with an increase in Quaternary volcanism, the increased volcanism itself may not have been the primary cause of global cooling.

  19. Ridge push engine of plate tectonics

    NASA Astrophysics Data System (ADS)

    Swedan, N. H.

    2015-07-01

    Convection of the upper mantle drives the tectonic plates. This convection is a thermodynamic cycle that exchanges heat and mechanical work between mantle and tectonic plates. Thermodynamics and observations indicate that the energy of the geological activities resulting from plate tectonics is equal to the latent heat of melting, calculated at mantle's pressure, of the new ocean crust regenerated at midocean ridges. This energy varies with the temperature of ocean floor, which is correlated with surface temperature. The main objective of this manuscript is to demonstrate that plate tectonics is a thermodynamic engine and can be calculated as such. Unlike existing tectonic models, the thermodynamic model is very sensitive to variations of the temperature of ocean floor, which is correlated with surface temperature. Therefore, the observed increase of geological activities can be projected with surface temperature rise. Other objectives of the manuscript are to calculate the force that drives the tectonic plates, estimate the energy released, and validate the calculations based on experiments and observations. In addition to the scientific merit of projecting the geological activities, a good projection can have a broader impact at the societal and economical levels. Investment and insurance related decisions are affected by climate change, and our ability to project the geological activities is of paramount importance for the economy and public safety. This work can thus provide tools to assess the risks and hazards associated with the trend of geological activities with surface temperature rise.

  20. Oak Ridge Reservation environmental report for 1990

    SciTech Connect

    Wilson, A.R.

    1991-09-01

    The purpose of this report is to provide information to the public about the impact of the US Department of Energy's (DOE's) facilities located on the Oak Ridge Reservation (ORR) on the public and the environment. It describes the environmental surveillance and monitoring activities conducted at and around the DOE facilities operated by Martin Marietta Energy Systems, Inc. Preparation and publication of this report is in accordance with DOE Order 5400.1. The order specifies a publication deadline of June of the following year for each calendar year of data. The primary objective of this report is to summarize all information collected for the previous calendar year regarding effluent monitoring, environmental surveillance, and estimates of radiation and chemical dose to the surrounding population. When multiple years of information are available for a program, trends are also evaluated. The first seven sections of Volume 1 of this report address this objective. The last three sections of Volume 1 provide information on solid waste management, special environmental studies, and quality assurance programs.

  1. Crush Testing at Oak Ridge National Laboratory

    SciTech Connect

    Feldman, Matthew R

    2011-01-01

    The dynamic crush test is required in the certification testing of some small Type B transportation packages. International Atomic Energy Agency regulations state that the test article must be 'subjected to a dynamic crush test by positioning the specimen on the target so as to suffer maximum damage.' Oak Ridge National Laboratory (ORNL) Transportation Technologies Group performs testing of Type B transportation packages, including the crush test, at the National Transportation Research Center in Knoxville, Tennessee (United States). This paper documents ORNL's experiences performing crush tests on several different Type B packages. ORNL has crush tested five different drum-type package designs, continuing its 60 year history of RAM package testing. A total of 26 crush tests have been performed in a wide variety of package orientations and crush plate CG alignments. In all cases, the deformation of the outer drum created by the crush test was significantly greater than the deformation damage caused by the 9 m drop test. The crush test is a highly effective means for testing structural soundness of smaller nondense Type B shipping package designs. Further regulatory guidance could alleviate the need to perform the crush test in a wide range of orientations and crush plate CG alignments.

  2. Episodes of Aleutian Ridge explosive volcanism

    USGS Publications Warehouse

    Hein, J.R.; Scholl, D. W.; Miller, J.

    1978-01-01

    Earlier workers have overlooked deep-sea bentonite beds when unraveling the Cenozoic volcanic history of an area. In the North Pacific, identification of Miocene and older volcanic episodes is possible only if both altered (bentonite) and unaltered ash beds are recognized. Our study, which includes bentonite beds, shows that volcanism on the Aleutian Ridge and Kamchatka Peninsula has been cyclic. Volcanic activity seems to have increased every 2.5 ?? 10 6 years for the past 10 ?? 106 years and every 5.0 ?? 106 years for the time span from 10 to 20 ?? 10 6 years ago. The middle and late Miocene and the Quaternary were times of greatly increased volcanic activity in the North Pacific and elsewhere around the Pacific Basin. The apparent absence of a volcanic record before the late Miocene at Deep Sea Drilling Project site 192 is the result not of plate motion, as suggested by Stewart and by Ninkovich and Donn, but rather of the diagenesis of ash layers. Major, apparently global volcanic episodes occurred at least twice in the last 20 ?? 106 years. Yet, only one major glacial epoch (the Pleistocene) has occurred. Therefore, even though glaciation coincided with an increase in Quaternary volcanism, the increased volcanism itself may not have been the primary cause of global cooling. Copyright ?? 1978 AAAS.

  3. Melt anomalies and propagating ridge offsets: Insights from the East Pacific Rise and Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Carbotte, S. M.; Marjanovic, M.; Nedimovic, M. R.; Canales, J.

    2010-12-01

    Recent observations of crustal structure associated with propagating ridge offsets at both the Endeavour and East Pacific Rise (EPR) ISS indicate local crustal thickness anomalies are associated with propagating ridge tips and renew the question of the role of melt anomalies in driving ridge propagation. Seismic and gravity data from the flanks of the Endeavour and adjoining segments of the Juan de Fuca Ridge reveal a 10-20 km wide zone of thicker and possibly denser crust on the young crust side of pseudofaults left by former propagating offsets. A sequence of bright ridge-ward dipping sub-Moho seismic reflections underlie the region of thicker crust and are interpreted as frozen magma sills at the base of the crust emplaced behind the propagating ridge tips [Nedimovic et al., 2005]. Crust within the pseudofault zones is denser and the presence of iron-enriched compositions is inferred, with the sub-crust magma sills the presumed source magma bodies for these denser, iron-enriched crustal rocks. Comparisons with the well-studied overlapping spreading center discontinuity at the EPR 9°03’N reveals a similar suite of crustal anomalies. On the flanks of this southward propagating discontinuity, an ~20 km wide band of crust that is both thicker and denser is located behind the V-shaped discordant zone of the OSC [Canales et al., 2002; Toomey and Hooft, 2008]. A broad swath of higher crustal magnetizations encompasses the region of thicker and denser crust as well as the adjoining discordant zone of relict OSC ridge tips and overlap basins [Carbotte and Macdonald, 1992]. At the southern edge of the band of thick crust, Singh et al. [2008] find evidence for a large melt anomaly in the lower crust and anomalously thick crust at the propagating eastern ridge of the OSC. The presence of local melt accumulations inferred from these bands of thicker crust behind propagating ridge offsets at both EPR and Juan de Fuca, presumably contributes to the forces driving ridge

  4. Melt generation beneath Arctic Ridges: Implications from U decay series disequilibria in the Mohns, Knipovich, and Gakkel Ridges

    NASA Astrophysics Data System (ADS)

    Elkins, L. J.; Sims, K. W. W.; Prytulak, J.; Blichert-Toft, J.; Elliott, T.; Blusztajn, J.; Fretzdorff, S.; Reagan, M.; Haase, K.; Humphris, S.; Schilling, J.-G.

    2014-02-01

    We present new 238U-230Th-226Ra-210Pb, 235U-231Pa, and Nd, Sr, Hf, and Pb isotope data for the slow- to ultraslow-spreading Mohns, Knipovich, and Gakkel Ridges. Combined with previous work, our data from the Arctic Ridges cover the full range of axial depths from the deep northernmost Gakkel Ridge shallowing upwards to the Knipovich, Mohns, and Kolbeinsey Ridges north of Iceland. Age-constrained samples from the Mohns and Knipovich Ridges have (230Th/238U) activity ratios ranging from 1.165 to 1.30 and 1.101 to 1.225, respectively. The high 230Th excesses of Kolbeinsey, Mohns, and Knipovich mid-ocean ridge basalts (MORB) are erupted from ridges producing relatively thin (Mohns, Knipovich) to thick (Kolbeinsey) oceanic crust with evidence for sources ranging from mostly peridotite (Kolbeinsey) to eclogite-rich mantle (Mohns, Knipovich). Age-constrained lavas from 85°E on the Gakkel Ridge, on the other hand, overlie little to no crust and range from small (˜5%) 230Th excesses to small 238U excesses (˜5%). The strong negative correlation between (230Th/238U) values vs. axial ridge depth among Arctic ridge basalts is controlled not only by solidus depth influence on 238U-230Th disequilibria, but also by variations in mantle source lithology and depth to the base of the lithosphere, which is expected to vary at ultra-slow spreading ridges. Small 231Pa excesses (65% excess) in age-constrained basalts support the presence of eclogite in the mantle source for this region. Conversely, the ultraslow-spreading Gakkel Ridge basalts are homogeneous, with Sr, Nd, and Hf radiogenic isotopic signatures indicative of a long time-averaged depleted mantle source. The Gakkel samples have minimum (226Ra/230Th) ratios ranging from 3.07 to 3.65 ± 3%, which lie along and extend the global negative correlation between 226Ra and 230Th excesses observed in MORB. The new 230Th-226Ra data support a model for global MORB production in which deep melts record interaction with shallower

  5. Spherical accretion and AGN feedback

    NASA Astrophysics Data System (ADS)

    Nulsen, Paul

    2014-06-01

    For a supermassive black hole accreting from a hot, quasi-spherical atmosphere, it is almost inevitable that the fluid approximation fails inside some point within the Bondi radius, but well outside the black hole event horizon. Within the region where the particle mean free paths exceed the radius, the flow must be modeled in terms of the Fokker-Planck equation. In the absence of magnetic fields, it is analogous to the "loss cone" problem for consumption of stars by a black hole. The accretion rate is suppressed well below the Bondi accretion rate and a significant power must be conveyed outward for the flow to proceed. This situation is complicated significantly by the presence of a magnetic field, but I will argue that the main outcomes are similar. I will also argue that the power emerging from such a flow, although generally far too little to suppress cooling on large scales, is an important ingredient of the AGN feedback cycle on scales comparable to the Bondi radius.

  6. Oak Ridge Dose Reconstruction Project Summary Report; Reports of the Oak Ridge Dose Reconstruction, Vol. 7

    SciTech Connect

    Thomas E. Widner; et. al.

    1999-07-01

    In the early 1990s, concern about the Oak Ridge Reservation's past releases of contaminants to the environment prompted Tennessee's public health officials to pursue an in-depth study of potential off-site health effects at Oak Ridge. This study, the Oak Ridge dose reconstruction, was supported by an agreement between the U.S. Department of Energy (DOE) and the State of Tennessee, and was overseen by a 12-member panel of individuals appointed by Tennessee's Commissioner of Health. The panel requested that the principal investigator for the project prepare the following report, ''Oak Ridge Dose Reconstruction Project Summary Report,'' to serve the following purposes: (1) summarize in a single, less technical report, the methods and results of the various investigations that comprised the Phase II of the dose reconstruction; (2) describe the systematic searching of classified and unclassified historical records that was a vital component of the project; and (3) summarize the less detailed, screening-level assessments that were performed to evaluate the potential health significance of a number of materials, such a uranium, whose priority did not require a complete dose reconstruction effort. This report describes each major step of the dose reconstruction study: (1) the review of thousands of historical records to obtain information relating to past operations at each facility; (2) estimation of the quantity and timing of releases of radioiodines from X-10, of mercury from Y-12, of PCB's from all facilities, and of cesium-137 and other radionuclides from White Oak Creek; (3) evaluation of the routes taken by these contaminants through the environment to nearby populations; and (4) estimation of doses and health risks to exposed groups. Calculations found the highest excess cancer risks for a female born in 1952 who drank goat milk; the highest non-cancer health risk was for children in a farm family exposed to PCBs in and near East Fork Poplar Creek. More detailed

  7. Mesoscopic structural analysis of bedrock exposures at the Oak Ridge K-25 Site, Oak Ridge, Tennessee

    SciTech Connect

    Lemiszki, P.J.

    1995-07-01

    This document presents the detailed study of outcrop of mesoscopic structures during the geologic mapping completed in 1992-1993. The purpose of this study was to document the geometry and style of outcrop scale structures, such as fractures and faults and relate them to map scale structures present in the Oak Ridge K-25 Area. This report was prepared to document site characterization data collected during the scoping phase investigations in accordance with the requirements of the Comprehensive Environmental Response, Compensation, and Liability Act.

  8. Data Sharing Report Characterization of Isotope Row Facilities Oak Ridge National Laboratory Oak Ridge TN

    SciTech Connect

    Weaver, Phyllis C

    2013-12-12

    The U.S. Department of Energy (DOE) Oak Ridge Office of Environmental Management (EM-OR) requested that Oak Ridge Associated Universities (ORAU), working under the Oak Ridge Institute for Science and Education (ORISE) contract, provide technical and independent waste management planning support using funds provided by the American Recovery and Reinvestment Act (ARRA). Specifically, DOE EM-OR requested ORAU to plan and implement a survey approach, focused on characterizing the Isotope Row Facilities located at the Oak Ridge National Laboratory (ORNL) for future determination of an appropriate disposition pathway for building debris and systems, should the buildings be demolished. The characterization effort was designed to identify and quantify radiological and chemical contamination associated with building structures and process systems. The Isotope Row Facilities discussed in this report include Bldgs. 3030, 3031, 3032, 3033, 3033A, 3034, 3036, 3093, and 3118, and are located in the northeast quadrant of the main ORNL campus area, between Hillside and Central Avenues. Construction of the isotope production facilities was initiated in the late 1940s, with the exception of Bldgs. 3033A and 3118, which were enclosed in the early 1960s. The Isotope Row facilities were intended for the purpose of light industrial use for the processing, assemblage, and storage of radionuclides used for a variety of applications (ORNL 1952 and ORAU 2013). The Isotope Row Facilities provided laboratory and support services as part of the Isotopes Production and Distribution Program until 1989 when DOE mandated their shutdown (ORNL 1990). These facilities performed diverse research and developmental experiments in support of isotopes production. As a result of the many years of operations, various projects, and final cessation of operations, production was followed by inclusion into the surveillance and maintenance (S&M) project for eventual decontamination and decommissioning (D&D). The

  9. Geophysical Surveys of a Known Karst Feature, Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    Doll, W.E.; Nyquist, J.E.; Carpenter, P.J.; Kaufmann, R.D.; Carr, B.J.

    1998-12-01

    Geophysical data were acquired at a site on the Oak Ridge Reservation, Tennessee to determine the characteristics of a mud-filled void and to evaluate the effectiveness of a suite of geophysical methods at the site. Methods that were used included microgravity, electrical resistivity, and seismic refraction. Both microgravity and resistivity were able to detect the void as well as overlying structural features. The seismic data provide bedrock depth control for the other two methods, and show other effects that are caused by the void.

  10. Project plan for the Background Soil Characterization Project on the Oak Ridge Reservation, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1992-08-01

    The Background Soil characterization Project (BSCP) will provide background concentration levels of selected metals, organic compounds, and radionuclides in soils from uncontaminated on-site areas at the Oak Ridge Reservation (ORR), and off-site in the western part of Roane County and the eastern part of Anderson County. The BSCP will establish a database, recommend how to use the data for contaminated site assessment, and provide estimates of the potential human health and environmental risks associated with the background level concentrations of potentially hazardous constituents.

  11. INDEPENDENT VERIFICATION OF THE BUILDING 3550 SLAB AT OAK RIDGE NATIONAL LABORATORY OAK RIDGE, TENNESSEE

    SciTech Connect

    Weaver, Phyllis C.

    2012-05-08

    The Oak Ridge Institute for Science and Education (ORISE) has completed the independent verification survey of the Building 3550 Slab. The results of this effort are provided. The objective of this verification survey is to provide independent review and field assessment of remediation actions conducted by Safety and Ecology Corporation (SEC) to document that the final radiological condition of the slab meets the release guidelines. Verification survey activities on the Building 3550 Slab that included scans, measurements, and the collection of smears. Scans for alpha, alpha plus beta, and gamma activity identified several areas that were investigated.

  12. Geophysical Surveys of a Known Karst Feature, Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    Carpenter, P.J.; Carr, B.J.; Doll, W.E.; Kaufmann, R.D.; Nyquist, J.E.

    1999-11-14

    Geophysical data were acquired at a site on the Oak Ridge Reservation, Tennessee to determine the characteristics of a mud-filled void and to evaluate the effectiveness of a suite of geophysical methods at the site. Methods that were used included microgravity, electrical resistivity, and seismic refraction. Both microgravity and resistivity were able to detect the void as well as overlying structural features. The seismic data provide bedrock depth control for the other two methods, and show other effects that are caused by the void.

  13. Criticality emergency planning at Oak Ridge National Laboratory

    SciTech Connect

    Green, J.H.; Cain, G.C.

    1983-01-01

    A plan to protect personnel and control the spread of contamination in the event of a radiation accident at Oak Ridge National Laboratory (ORNL) is outlined. Procedures and personnel are presented. (ACK)

  14. Mid-ocean ridge dynamics - Observations and theory

    SciTech Connect

    Phipps morgan, J. )

    1991-01-01

    Recent observational and theoretical investigations of midocean-ridge extension and its relation to melting, magmatic, deformation, and hydrothermal processes are discussed in a critical review of U.S. research from the period 1987-1990. Topics examined include segmentation, along-axis crustal variations and gravity, axial crust and lithosphere structure and seismics, ophiolite studies, and the interaction of ridge and continental rift studies. Consideration is given to theoretical models of axial topography; mantle flow, melting, and melt migration; mantle rheology and flow beneath a midoceanic ridge; upwelling structure and segmentation; the role of the lithosphere in shaping ridge segmentation; thermal stress and the origin of fracture zones; and hydrothermal cooling. A comprehensive bibliography is provided.

  15. 23. Detail, ridge cresting and finial elements, deteriorated slates, southeast ...

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

    23. Detail, ridge cresting and finial elements, deteriorated slates, southeast roof slope, view to northwest from lift-bed truck, 135mm lens. - Southern Pacific Depot, 559 El Camino Real, San Carlos, San Mateo County, CA

  16. 60 years of great science [Oak Ridge National Laboratory

    SciTech Connect

    2003-01-01

    This issue highlights Oak Ridge National Laboratory's contributions in more than 30 areas of research and related activities during the past 60 years and provides glimpses of current activities that are carrying on this heritage.

  17. Specialized ependymal ridges in the cerebral aqueduct of the rat.

    PubMed

    Welsh, M G; Beitz, A J

    1981-11-18

    Novel paired ependymal ridges (EPRS) have been identified in the ventrolateral wall of the cerebral aqueduct of the rat. Scanning electron microscopic techniques revealed that the dorsolateral and ventromedial ridges differ from each other in surface morphology. Using the PAP immunohistochemical technique, the EPRS demonstrate a dense innervation of both serotonin and LH-RH fibers when compared to the surrounding midbrain periaqueductal gray and the "non-ridge" ependyma of the aqueduct. Each ridge is composed of a single layer of ependymal cells with a central core of subependymal cells and numerous blood vessels. Ependymal cells resembling tanycytes extend between the lumen of the aqueduct and the subependymal capillaries. It is suggested that the EPRS may serve as sites for the release of neurochemicals into the cerebrospinal fluid.

  18. 3. ENVIRONMENT, FROM SOUTH, SHOWING RIVER ROAD RIDGE CARRYING CASSELMAN ...

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

    3. ENVIRONMENT, FROM SOUTH, SHOWING RIVER ROAD RIDGE CARRYING CASSELMAN RIVER ROAD OVER CASSELMAN RIVER - River Road Bridge, Crossing Casselman River on Casselman River Road, Grantsville, Garrett County, MD

  19. Nested Paleozoic successor basins in the southern Appalachian Blue Ridge

    SciTech Connect

    Tull, J.F.; Groszos, M.S. )

    1990-11-01

    Field studies in the southern Appalachian Blue Ridge and its southwest extension, the Talladega belt, indicate that in at least three regions, polydeformed and metamorphosed turbidite-dominated sequences unconformably overlie rifted-margin continental-terrace wedge clastic rocks and overlying carbonate-platform deposits. These sequences are (1) the Talladega Group (in the Talladega belt), (2) the Walden Creek Group (along the west flank of the Blue Ridge), and (3) the Mineral Bluff Formation (within the core of the Blue Ridge). Paleontologic evidence indicates that the Talladega and Walden Creek Groups are in part as young as Silurian-Devonian. The presence of these anomalously young sequences unconformably above the trailing-margin stratigraphy in the Blue Ridge brings into question conventional ideas of the timing and nature of the tectonic evolution of the ancient continental margin.

  20. Ridges on Europa: Origin by Incremental Ice-Wedging

    NASA Technical Reports Server (NTRS)

    Melosh, H. J.; Turtle, E. P.

    2004-01-01

    The surface of Europa is covered by ridges that display a variety of morphologies . The most common type is characterized by a double ridge divided by an axial trough. These ridges are, in general, narrow (typically only a few km across) and remarkably linear. They are up to a few hundred meters high and the inner and outer slopes appear to stand at the angle of repose . A number of diverse mechanisms have been proposed to explain the formation of these ubiquitous features , although none can fully account for all of their observed characteristics. We propose a different formation theory in which accumulation of material within cracks that open during the extensional phase of the tidal cycle prevents complete closure of the cracks during the tidal cycle s compressional phase. This accumulation deforms the surrounding ice and, in time, results in the growth of a landform remarkably similar to the ridges observed on Europa.

  1. The Tucker technique: conservative molar inlays preserving the transverse ridge.

    PubMed

    Hess, T A; Wadhwani, C P K

    2012-01-01

    Conservation of healthy tooth structure should be the aim of any restorative procedure. Two inlays may be an ideal choice for the treatment of maxillary molars to preserve the transverse ridge and maintain structural integrity.

  2. Technical Evaluation of Oak Ridge Filter Test Facility

    SciTech Connect

    KRISKOVICH, J.R.

    2002-01-25

    Two evaluations of the Oak Ridge Department of Energy (DOE) Filter Test Facility (FTF) were performed on December 11 and 12, 2001, and consisted of a quality assurance and a technical evaluation. This report documents results of the technical evaluation.

  3. 36. View of southern terminus of the Blue Ridge Parkway ...

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

    36. View of southern terminus of the Blue Ridge Parkway looking SW. - Great Smoky Mountains National Park Roads & Bridges, Newfound Gap Road, Between Gatlinburg, TN & Cherokee, NC, Gatlinburg, Sevier County, TN

  4. Science and Technology at Oak Ridge National Laboratory

    ScienceCinema

    Mason, Thomas

    2016-07-12

    ORNL Director Thom Mason explains the groundbreaking work in neutron sciences, supercomputing, clean energy, advanced materials, nuclear research, and global security taking place at the Department of Energy's Office of Science laboratory in Oak Ridge, Tenn.

  5. 23. Newfound Gap Road, Fancy Ridge, overlook with ugly railing. ...

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

    23. Newfound Gap Road, Fancy Ridge, overlook with ugly railing. - Great Smoky Mountains National Park Roads & Bridges, Newfound Gap Road, Between Gatlinburg, TN & Cherokee, NC, Gatlinburg, Sevier County, TN

  6. Science and Technology at Oak Ridge National Laboratory

    SciTech Connect

    Mason, Thomas

    2012-11-01

    ORNL Director Thom Mason explains the groundbreaking work in neutron sciences, supercomputing, clean energy, advanced materials, nuclear research, and global security taking place at the Department of Energy's Office of Science laboratory in Oak Ridge, Tenn.

  7. Feedback and assessment for clinical placements: achieving the right balance

    PubMed Central

    Burgess, Annette; Mellis, Craig

    2015-01-01

    During clinical placements, the provision of feedback forms an integral part of the learning process and enriches students’ learning experiences. The purpose of feedback is to improve the learner’s knowledge, skills, or behavior. Receipt of accurate feedback can help to narrow the gap between actual and desired performance. Effective and regular feedback has the potential to reinforce good practice and motivate the learner toward the desired outcome. Despite the obvious role of feedback in effective teaching and learning, a common complaint from students is that they do not receive adequate feedback. Unfortunately, skills in giving and receiving feedback are rarely taught to students or clinicians. This study aims to provide an understanding of the role of feedback within the learning process, consider consequences of inadequate or poorly given feedback, consider the barriers to the feedback process, provide practical guidelines for providing feedback, and consider the need for student and faculty development in feedback skills. PMID:26056511

  8. Operation of PEP longitudinal feedback system

    SciTech Connect

    Allen, M.A.; Karvonen, L.G.; McConnell, R.A.; Schwarz, H.

    1981-03-01

    In order to suppress longitudinal coupled-bunch oscillations which might limit the capabilities of PEP, the 18 GeV e/sup +/e/sup -/ storage ring at SLAC, a longitudinal feedback system is utilized. A frequency domain feedback system was chosen with the frequency spectrum of the stored beam being sampled close to a symmetry point in the ring where the feedback cavity itself is also located. The symmetry point chosen is symmetry point 5 which lies half-way between interaction regions 4 and 6. The system has been installed in PEP and is now operational. However, at stored currents up to the maximum stored in PEP to date at 14.5 GeV (approximately 40 mA in 6 bunches), the ring has been stable to all modes of longitudinal coupled-bunch oscillations both barycentric and the other fundamental modes. By deliberately detuning the main accelerating cavities, small multibunch oscillations can be introduced which, in turn, can be damped by the feedback system. Under optimized beam conditions the feedback system could be adjusted to positive feedback and excite oscillations with relatively small power to the feedback cavity. This will be described along with other details of the system.

  9. Pseudo-Haptic Feedback in Teleoperation.

    PubMed

    Neupert, Carsten; Matich, Sebastian; Scherping, Nick; Kupnik, Mario; Werthschutzky, Roland; Hatzfeld, Christian

    2016-01-01

    In this paper, we develop possible realizations of pseudo-haptic feedback in teleoperation systems based on existing works for pseudo-haptic feedback in virtual reality and the intended applications. We derive four potential factors affecting the performance of haptic feedback (calculation operator, maximum displacement, offset force, and scaling factor), which are analyzed in three compliance identification experiments. First, we analyze the principle usability of pseudo-haptic feedback by comparing information transfer measures for teleoperation and direct interaction. Pseudo-haptic interaction yields well above-chance performance, while direct interaction performs almost perfectly. In order to optimize pseudo-haptic feedback, in the second study we perform a full-factorial experimental design with 36 subjects performing 6,480 trials with 36 different treatments. Information transfer ranges from 0.68 bit to 1.72 bit in a task with a theoretical maximum of 2.6 bit, with a predominant effect of the calculation operator and a minor effect of the maximum displacement. In a third study, short- and long-term learning effects are analyzed. Learning effects regarding the performance of pseudo-haptic feedback cannot be observed for single-day experiments. Tests over 10 days show a maximum increase in information transfer of 0.8 bit. The results show the feasibility of pseudo-haptic feedback for teleoperation and can be used as design basis for task-specific systems.

  10. The Kaena Ridge Submarine Rift Zone off Oahu, Hawaii

    NASA Astrophysics Data System (ADS)

    Smith, J. R.

    2002-12-01

    Deep-water multibeam data was collected in the Kauai Channel between the islands of Kauai and Oahu during the years 2000 to 2002 using the R/V Roger Revelle in support of the NSF funded Hawaii Ocean Mixing Experiment (HOME) with M. Gregg and A. Chave as principal investigators. The bathymetric surveys covered the Kaena Ridge, possibly a large submarine rift zone extension of the Waianae Volcano that makes up the western half of the island of Oahu. The Kaena ridge is bordered by the Kauai Channel and debris avalanche deposit material to the west, the Waianae slump to the south, and the Kaena slump to the north. The 35-55 km wide crest of the Kaena ridge extends 75-100 km northwest from Kaena Point, the westernmost tip of Oahu. The length and morphology resemble that of the Hana Ridge, the submarine extension of the Haleakala east rift zone. The broad central portion of Kaena ridge is comprised of two apparent lava shields 15 km and 10 km in diameter, both rising 200 m above the ridge (approximately 2500 m above the basal seafloor) to within 880 m and 660 m of sea level, respectively. The large size and distant location of the westernmost cone in the middle of the Kauai Channel suggests that it might predate Waianae Volcano and represent a precursor to the island of Oahu in the Hawaiian Chain, aborted before it ever reached sea level. Several 1500 m high steep concave landslide scars facing the giant Waianae slump mark the southern side of the ridge. To the north, a series of four 15 to 30 km wide benches step down to the basal seafloor, forming the Kaena slump, which may represent a less developed version of the Waianae slump. A 42 km long and 22 km wide (at its center) narrow rift zone ridge, in the classic Hawaiian submarine rift zone style (e.g., Puna ridge), bifurcates from the main broad ridge near the distal end. The smaller ridge trends north-northwest and is covered with approximately a dozen volcanic cones along its axis. Its rough morphology is

  11. Footprint ridge density: a new attribute for sexual dimorphism.

    PubMed

    Kanchan, T; Krishan, K; Aparna, K R; Shyamsunder, S

    2012-12-01

    Estimation of sex of footprints can help in establishing the biological profile of potential suspects. This research attempts to study the sex differences in the ridge density in four different areas of a footprint. The study sample comprises footprints from both feet of 106 adult subjects from India that were analysed using standardized techniques. A total of 212 footprints were studied in detail. The four areas analysed in the study included the upper portion of the medial border of the great toe (F1), the ball of the great toe (F2), the ball of the 5th toe below the triradius point (F3) and the central prominent part of the heel (F4). Male-female differences in footprint ridge density were statistically analysed for each designated area and compared between right and left sides. The mean footprint ridge density was significantly higher among females than males in all designated areas (p<0.05) in both feet. No right-left differences were apparent in the analysed areas. Variations in footprint ridge density between different areas in right and left feet were evident among males and females. This study observes that sex differences exist in footprint ridge density among humans. Maximum sex differences were observed for ridge density in medial ball area, followed by great toe, lateral ball and minimum sex differences were observed in the heel region. It is observed that sex can be estimated from footprint ridge density with reasonable accuracy. The sexing potential of total footprint ridge density was 82.6% from the right and 83.6% from the left footprints respectively.

  12. The Oak Ridge Reservation Annual Site Environmental Report Summary, 2007

    SciTech Connect

    None, None

    2009-02-28

    The Oak Ridge Reservation Annual Site Environmental Report is prepared and published each year to inform the public of the environmental activities that take place on the reservation and in the surrounding areas. It is written to comply with DOE Order 231.1A, Environment, Safety, and Health Reporting. This document has been prepared to present the highlights of the Oak Ridge Reservation Annual Site Environmental Report 2007 in an easy-to-read, summary format.

  13. Petroleum associated with polymetallic sulfide in sediment from Gorda Ridge

    USGS Publications Warehouse

    Kvenvolden, K.A.; Rapp, J.B.; Hostettler, F.D.; Morton, J.L.; King, J.D.; Claypool, G.E.

    1986-01-01

    A sediment sample, impregnated with asphaltic petroleum and polymetallic sulfide, was dredged from the southern end of Gorda Ridge (the Escanaba Trough) off northern California, within the offshore Exclusive Economic Zone of the United States. The molecular distributions of hydrocarbons in this petroleum show that it was probably derived from terrestrial organic matter in turbidite sediment filling the Escanaba Trough. Hydrothermal activity at the Gorda Ridge spreading center provided the heat for petroleum formation and was the source of fluids for sulfide mineralization.

  14. Mica deposits of the Blue Ridge in North Carolina

    USGS Publications Warehouse

    Lesure, Frank Gardner

    1968-01-01

    Pegmatites in the Blue Ridge of North Carolina are important sources of sheet and scrap mica, feldspar, kaolin, and quartz.  Small amounts of beryl, columbite-tantalite, monazite, samarskite, and uranium minerals also have been produced.  The mica-bearing pegmatites occur in mica and hornblende gneiss and schist throughout the Blue Ridge province but are concentrated in the Spruce Pine and Franklin-Sylva districts.

  15. Ridge Waveguide Structures in Magnesium-Doped Lithium Niobate

    NASA Technical Reports Server (NTRS)

    Himmer, Phillip; Battle, Philip; Suckow, William; Switzer, Greg

    2011-01-01

    This work proposes to establish the feasibility of fabricating isolated ridge waveguides in 5% MgO:LN. Ridge waveguides in MgO:LN will significantly improve power handling and conversion efficiency, increase photonic component integration, and be well suited to spacebased applications. The key innovation in this effort is to combine recently available large, high-photorefractive-damage-threshold, z-cut 5% MgO:LN with novel ridge fabrication techniques to achieve high-optical power, low-cost, high-volume manufacturing of frequency conversion structures. The proposed ridge waveguide structure should maintain the characteristics of the periodically poled bulk substrate, allowing for the efficient frequency conversion typical of waveguides and the high optical damage threshold and long lifetimes typical of the 5% doped bulk substrate. The low cost and large area of 5% MgO:LN wafers, and the improved performance of the proposed ridge waveguide structure, will enhance existing measurement capabilities as well as reduce the resources required to achieve high-performance specifications. The purpose of the ridge waveguides in MgO:LN is to provide platform technology that will improve optical power handling and conversion efficiency compared to existing waveguide technology. The proposed ridge waveguide is produced using standard microfabrication techniques. The approach is enabled by recent advances in inductively coupled plasma etchers and chemical mechanical planarization techniques. In conjunction with wafer bonding, this fabrication methodology can be used to create arbitrarily shaped waveguides allowing complex optical circuits to be engineered in nonlinear optical materials such as magnesium doped lithium niobate. Researchers here have identified NLO (nonlinear optical) ridge waveguide structures as having suitable value to be the leading frequency conversion structures. Its value is based on having the low-cost fabrication necessary to satisfy the challenging pricing

  16. High-Resolution Image of Europa's Ridged Plains

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This spectacular image taken by NASA's Galileo spacecraft camera shows a region of ridged plains on Jupiter's moon Europa. The plains are comprised of many parallel and cross-cutting ridges, commonly in pairs. The majority of the region is of very bright, but darker material is seen primarily in valleys between ridges. Some of the most prominent ridges have dark deposits along their margins and in their central valleys. Some of this dark material probably moved down the flanks of the ridges and has piled up along their bases. The most prominent ridges are about a kilometer in width (less than a mile). In the top right hand corner of the image the end of a dark wide ridge (about 2 kilometers or 1.2 miles across) is visible. Several deep fractures cut through this ridge and continue into the plains. The brightness of the region suggests that frost covers much of Europa's surface. This image looks different from those obtained earlier in Galileo's mission, because this image was taken with the Sun higher in Europa's sky.

    This image was taken on December 16, 1997 at a range of 1,300 kilometers (800 miles) by Galileo's solid state imaging system. North is to the top of the picture, and the Sun illuminates the surface from the upper left. This image, centered at approximately 14 degrees south latitude and 194 degrees west longitude, covers an area approximately 20 kilometers (12 miles) on each side. The resolution is 26 meters (85 feet) per picture element.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

  17. Characterizing Cratering at the Iapetus Equatorial Ridge using Stereo Topography

    NASA Astrophysics Data System (ADS)

    Persaud, D. M.

    2015-12-01

    Since the arrival of the Cassini probe to the Saturnian system in 2004, the flattened shape and extreme equatorial ridge of the moon Iapetus have posed a number of questions regarding its geophysical evolution. Current models suggest either tidal despinning or a collapsed ring system formed the ridge, with 26Al decay serving as an additional heating mechanism and warm ice or liquid water beneath a thick lithosphere potentially allowing for large-scale topography and deformation to occur (Sandwell and Schubert 2010). Structure at the ridge itself provides further questions in understanding the deformation of Iapetus at its equator. Persaud and Phillips (2014) use stereo topography to present a trend of crater relaxation and crater diameter that suggests a secondary heating event has relaxed younger, smaller craters focused at this region. The extreme slopes along the ridge, however, complicate understanding the order of events that have occurred on Iapetus, including ridge formation, crater relaxation, secondary thermal events, and mass wasting. We use topographic profiles of Iapetus impact craters extracted from digital elevation models (DEMs) constructed with stereo images from the Cassini ISS Instrument to characterize crater complexity and transition diameters versus crater floor geometry, proximity to the equatorial ridge, and relaxation percentage. We then use these results to begin to develop a geometric model of events at the ridge on Iapetus to understand its deformation history. We will present results and discussion of using stereo topography for these analyses. References: Sandwell, D., and G. Schubert. A contraction model for the flattening and equatorial ridge of Iapetus, Icarus 210, 817-822, 2010. Persaud, D.M., and C.B. Phillips. Methods of Estimating Initial Crater Depths on Icy Satellites using Stereo Topography, AGU Fall Meeting 2014, abstract 17043. This work was supported by the 2015 NASA Ames Academy for Space Exploration.

  18. Multi-beam surveys of the Michelson Ridge guyots: Subduction or obduction

    NASA Astrophysics Data System (ADS)

    Christian Smoot, N.

    1983-12-01

    This is the first graphic presentation of the Michelson Ridge in its entirety from a total coverage, multi-beam survey. The ridge splits the Izu and Bonin Trenches, is comprised of four guyots, and is anomalous to the strike of all other ridges heretofore discovered in the Pacific Ocean. The ridge is obducting/offscraping onto the Philippine plate instead of subducting.

  19. 75 FR 82001 - Environmental Management Site-Specific Advisory Board, Oak Ridge Reservation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-29

    ... Environmental Management Site-Specific Advisory Board, Oak Ridge Reservation AGENCY: Department of Energy... Site-Specific Advisory Board (EM SSAB), Oak Ridge Reservation. The Federal Advisory Committee Act... 12, 2011, 6 p.m. ADDRESSES: DOE Information Center, 475 Oak Ridge Turnpike, Oak Ridge,...

  20. 77 FR 45345 - Environmental Management Site-Specific Advisory Board, Oak Ridge Reservation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-31

    ... Environmental Management Site-Specific Advisory Board, Oak Ridge Reservation AGENCY: Department of Energy... Site-Specific Advisory Board (EM SSAB), Oak Ridge Reservation. The Federal Advisory Committee Act (Pub... Oak Ridge Operations Office, P.O. Box 2001, EM-90, Oak Ridge, TN 37831. Phone (865) 241-3315; Fax...

  1. 75 FR 43518 - Environmental Management Site-Specific Advisory Board, Oak Ridge Reservation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-26

    ... Environmental Management Site-Specific Advisory Board, Oak Ridge Reservation AGENCY: Department of Energy... Site-Specific Advisory Board (EM SSAB), Oak Ridge Reservation. The Federal Advisory Committee Act (Pub..., Department of Energy Oak Ridge Operations Office, P.O. Box 2001, EM-90, Oak Ridge, TN 37831. Phone (865)...

  2. Feedback Requirements for SASE-FELs

    SciTech Connect

    Loos, Henrik; /SLAC

    2012-07-06

    The operation of a Self Amplified Spontaneous Emission (SASE) Free Electron Lasers (FEL) at soft and hard X-ray wavelengths driven by a high brightness electron beam imposes strong requirements on the stability of the accelerator and feedback systems are necessary to both guarantee saturation of the SASE process as well as a stable photon beam for user experiments. Diagnostics for the relevant transverse and longitudinal beam parameters are presented and various examples of feedback systems for bunches with low repetition rate as well as systems for intra bunch train feedbacks are discussed.

  3. Feedback options in nonlinear numerical finance

    NASA Astrophysics Data System (ADS)

    Hugger, Jens; Mashayekhi, Sima

    2012-09-01

    Feedback options are options where information about the trading of the underlying asset is fed back into the pricing model. This results in nonlinear pricing models. A survey of the literature about feedback options in finance is presented. The pricing model for the full feedback option on an infinite slab is presented and boundary values on a bounded domain are derived. This bounded, nonlinear, 2 dimensional initial-boundary value problem is solved numerically using a number of standard finite difference schemes and the methods incorporated in the symbolic software Maple{trade mark, serif}.

  4. The effects of outcome and process feedback

    NASA Technical Reports Server (NTRS)

    Johnson, Debra Steele

    1990-01-01

    A study was conducted to examine the effects of process and outcome feedback on performance during a skill acquisition phase and a transfer test phase. The research also examined the role of two moderators: self-efficacy and intrinsic motivation. Subjects were college students participating for course credit. The task involved using a computerized simulation of the Space Shuttle's Remote Manipulation System (RMS). Results provided evidence of the beneficial effects of process feedback during skill acquisition. Results also provided evidence that self-efficacy and intrinsic motivation moderate the effects of feedback type on performance.

  5. Along ridge variation of the seafloor cooling and subsidence

    NASA Astrophysics Data System (ADS)

    Huang, Po-Ju; Chiao, Ling-Yun

    2013-04-01

    Bathymetry is linearly proportional to the square root of the seafloor age according to decades of observations. It is well explained by the essentially one-dimensional thermal contraction such as that demonstrated in the classical half-space cooling model and the subsequent 2-D modifications such as the plate model, GDH1 model, PSM model etc. However, much less efforts have been undertaken on study of variation of seafloor cooling along the ridge axis. We carefully examine corridors in the spreading direction that avoid seamounts and other some secondary structures, in addition to the sediment correction. We find that subsidence rates vary along major mid-ocean ridges. It would require a range of 400 to -600°C difference if the subsidence rate variations are attributed entirely to sub-ridge mantle temperature anomalies. Pronounced anomalies include the noticeable lows at the equator in the mid-Atlantic ridge and the northern section of East Pacific Rise that might be attributed to the close by continental lithosphere. The eastern section in mid-Indian ridge is also significantly cooler within regions of the Australian-Antarctic Discordance (AAD), which has been attributed to an ancient slab stalled beneath the present-day Southeast Indian Ridge (SEIR). Further researches that take into account of trends of geoid data is underway to make consistent interpretations.

  6. Tectonic evolution of Gorda Ridge inferred from sidescan sonar images

    USGS Publications Warehouse

    Masson, D.G.; Cacchione, D.A.; Drake, D.E.

    1988-01-01

    Gorda Ridge is the southern segment of the Juan de Fuca Ridge complex, in the north-east Pacific. Along-strike spreading-rate variation on Gorda Ridge and deformation of Gorda Plate are evidence for compression between the Pacific and Gorda Plates. GLORIA sidescan sonographs allow the spreading fabric associated with Gorda Ridge to be mapped in detail. Between 5 and 2 Ma, a pair of propagating rifts re-orientated the northern segment of Gorda Ridge by about 10?? clockwise, accommodating a clockwise shift in Pacific-Juan de Fuca plate motion that occurred around 5 Ma. Deformation of Gorda Plate, associated with southward decreasing spreading rates along southern Gorda Ridge, is accommodated by a combination of clockwise rotation of Gorda Plate crust, coupled with left-lateral motion on the original normal faults of the ocean crust. Segments of Gorda Plate which have rotated by different amounts are separated by narrow deformation zones across which sharp changes in ocean fabric trend are seen. Although minor lateral movement may occur on these NW to WNW structures, no major right-lateral movement, as predicted by previous models, is observed. ?? 1988 Kluwer Academic Publishers.

  7. Radioisotope production and management at Oak Ridge National Laboratory

    SciTech Connect

    Collins, E.D.; Aaron, W.S.; Alexander, C.W.; Bigelow, J.E.; Parks, J.T.; Tracy, J.G.; Wham, R.M.

    1994-09-01

    The production of radioisotopes has been one of the basic activities at Oak Ridge since the end of World War II. The importance of this work was best described by Alvin Weinberg, former Laboratory Director, when he wrote ``... If God has a golden book and writes down what it is that Oak Ridge National Laboratory did that had the biggest influence on science, I would guess that was the production and distribution of isotopes.`` Radioisotopes production continues to be an important aspect of Oak Ridge programs today and of those planned for the future. Past activities, current projects, and future plans and potentials will be described briefly in this paper. Also, some of the major issues facing the continued production of radioisotopes will be described. The scope of the program has always been primarily that of process development, followed by special batch-type productions, where no other supply exists. The technology developed has been available for adoption by US commercial corporations, and in cases where this has occurred, Oak Ridge has withdrawn as a supplier of the particular isotopes involved. One method of production that will not be described is that of target bombardment with an accelerator. This method was used at Oak Ridge prior to 1978 in the 86-inch Cyclotron. However, this method has not been used at Oak Ridge since then for radioisotope production, except as a research tool.

  8. Tidal conversion by a periodic array of ridges

    NASA Astrophysics Data System (ADS)

    Zhang, Likun; Paoletti, Matthew; Swinney, Harry

    2012-11-01

    The generation of internal waves by tidal flow over submarine topography such as ridges is the main source of internal tidal energy in the oceans. For multiple ridges the dependence of the radiated power on the ridge height and slope is different from that for an individual ridge, and for multiple ridges the power also depends on the spacing between the topographic features. Prior numerical and analytical studies on tidal generation by a periodic array of steep ridges suggest the possible saturation of conversion rate when the dimensionless height of the topography is large [S. Khatiwala, Deep-Sea Res. (2003); J. Nycander, J. Fluid. Mech. (2006); N. J. Balmforth and T. Peacock, J. Phys. Ocean. (2009)]. Here we perform 2D Navier-Stokes simulations and laboratory experiments on the generation of internal tides from a periodic array of supercritical barriers. We determine how the radiated power and saturation depend on the tidal flow, topography, and stratification. Supported by ONR MURI Grant N000141110701.

  9. Constrained circulation at Endeavour ridge facilitates colonization by vent larvae.

    PubMed

    Thomson, Richard E; Mihály, Steven F; Rabinovich, Alexander B; McDuff, Russell E; Veirs, Scott R; Stahr, Frederick R

    2003-07-31

    Understanding how larvae from extant hydrothermal vent fields colonize neighbouring regions of the mid-ocean ridge system remains a major challenge in oceanic research. Among the factors considered important in the recruitment of deep-sea larvae are metabolic lifespan, the connectivity of the seafloor topography, and the characteristics of the currents. Here we use current velocity measurements from Endeavour ridge to examine the role of topographically constrained circulation on larval transport along-ridge. We show that the dominant tidal and wind-generated currents in the region are strongly attenuated within the rift valley that splits the ridge crest, and that hydrothermal plumes rising from vent fields in the valley drive a steady near-bottom inflow within the valley. Extrapolation of these findings suggests that the suppression of oscillatory currents within rift valleys of mid-ocean ridges shields larvae from cross-axis dispersal into the inhospitable deep ocean. This effect, augmented by plume-driven circulation within rift valleys having active hydrothermal venting, helps retain larvae near their source. Larvae are then exported preferentially down-ridge during regional flow events that intermittently over-ride the currents within the valley.

  10. Effects of informative and confirmatory feedback on brain activation during negative feedback processing

    PubMed Central

    Woo, Yeon-kyoung; Song, Juyeon; Jiang, Yi; Cho, Catherine; Bong, Mimi; Kim, Sung-il

    2015-01-01

    The current study compared the effects of informative and confirmatory feedback on brain activation during negative feedback processing. For confirmatory feedback trials, participants were informed that they had failed the task, whereas informative feedback trials presented task relevant information along with the notification of their failure. Fourteen male undergraduates performed a series of spatial-perceptual tasks and received feedback while their brain activity was recorded. During confirmatory feedback trials, greater activations in the amygdala, dorsal anterior cingulate cortex, and the thalamus (including the habenular) were observed in response to incorrect responses. These results suggest that confirmatory feedback induces negative emotional reactions to failure. In contrast, informative feedback trials elicited greater activity in the dorsolateral prefrontal cortex (DLPFC) when participants experienced failure. Further psychophysiological interaction (PPI) analysis revealed a negative coupling between the DLPFC and the amygdala during informative feedback relative to confirmatory feedback trials. These findings suggest that providing task-relevant information could facilitate implicit down-regulation of negative emotions following failure. PMID:26175679

  11. Deformation of forearcs caused by subduction of aseismic ridges: The role of ridge orientation and convergence direction investigated with 3D finite-element models

    NASA Astrophysics Data System (ADS)

    Zeumann, Stefanie; Hampel, Andrea

    2015-04-01

    Subduction of aseismic oceanic ridges causes considerable deformation of the forearc region. To investigate the role of ridge orientation relative to the margin and convergence direction on the style of forearc deformation, we developed a series of 3D finite-elemente models, in which a rigid oceanic plate carrying the model ridge subducts beneath a deformable forearc wedge. Experiments were carried out for angles of 30°, 60° and 90° between the ridge axis and the trench and for different convergence directions. In the experiments, in which the ridge axis is parallel to the convergence direction, the ridge is stationary; in all other experiments, the ridge migrates along the margin and thus affects different regions of the forearc. Our results show that the ridge indents and uplifts the forearc in all models. For obliquely subducting ridges the displacement and strain fields become highly asymmetric regardless if the ridge is stationary or migrates along the forearc. Only if the ridge is stationary and oriented perpendicular to the margin, the deformation is symmetric relative to the ridge axis. Stationary ridges show uplift only above the ridge tip, whereas a migrating ridge causes a wave of uplift above the leading flank of the ridge followed by subsidence above the trailing flank. Horizontal strain components show domains of both extension and shortening, with extension occurring above the ridge tip and shortening above the ridge flanks. To compare our results with natural case studies, we computed additional models reflecting the setting of the stationary Cocos Ridge subducting beneath southern Costa Rica and of the Nazca Ridge, which migrates along the Peruvian margin. The results of these adjusted models are in good agreement with field observations. For the model of the Cocos Ridge the highest degree of shortening occurs normal to the margin, which coincides with the location of a thrust belt in the forearc of Costa Rica with its maximum shortening inboard

  12. Feedback on flood risk management

    NASA Astrophysics Data System (ADS)

    Moreau, K.; Roumagnac, A.

    2009-09-01

    For several years, as floods were increasing in South of France, local communities felt deprive to assume their mission of protection and information of citizens, and were looking for assistance in flood management. In term of flood disaster, the fact is that physical protection is necessary but inevitably limited. Tools and structures of assistance to anticipation remain slightly developed. To manage repeated crisis, local authorities need to be able to base their policy against flood on prevention, warnings, post-crisis analysis and feedback from former experience. In this objective, after 3 years of test and improvement since 2003, the initiative Predict-Services was developed in South of France: it aims at helping communities and companies to face repeated flood crisis. The principle is to prepare emergency plans, to organize crisis management and reduce risks; to help and assist communities and companies during crisis to activate and adapt their emergency plans with enough of anticipation; and to analyse floods effects and improve emergency plans afterwards. With the help of Meteo France datas and experts, Predict services helps local communities and companies in decision making for flood management. In order to reduce risks, and to keep the benefits of such an initiative, local communities and companies have to maintain the awareness of risk of the citizens and employees. They also have to maintain their safety plans to keep them constantly operational. This is a part of the message relayed. Companies, Local communities, local government authorities and basin stakeholders are the decision makers. Companies and local communities have to involve themselves in the elaboration of safety plans. They are also completely involved in their activation that is their own responsability. This applies to other local government authorities, like districts one's and basin stakeholders, which participle in the financing community safety plans and adminitrative district which

  13. Feedback on flood risk management

    NASA Astrophysics Data System (ADS)

    Moreau, K.; Roumagnac, A.

    2009-09-01

    For several years, as floods were increasing in South of France, local communities felt deprive to assume their mission of protection and information of citizens, and were looking for assistance in flood management. In term of flood disaster, the fact is that physical protection is necessary but inevitably limited. Tools and structures of assistance to anticipation remain slightly developed. To manage repeated crisis, local authorities need to be able to base their policy against flood on prevention, warnings, post-crisis analysis and feedback from former experience. In this objective, after 3 years of test and improvement since 2003, the initiative Predict-Services was developped in South of France: it aims at helping communities and companies to face repeated flood crisis. The principle is to prepare emergency plans, to organize crisis management and reduce risks; to help and assist communities and companies during crisis to activate and adapt their emergency plans with enough of anticipation; and to analyse floods effects and improve emergency plans afterwards. In order to reduce risks, and to keep the benefits of such an initiative, local communities and companies have to maintain the awareness of risk of the citizens and employees. They also have to maintain their safety plans to keep them constantly operational. This is a part of the message relayed. Companies, Local communities, local government authorities and basin stakeholders are the decision makers. Companies and local communities have to involve themselves in the elaboration of safety plans. They are also completely involved in their activation that is their own responsability. This applies to other local government authorities, like districts one's and basin stakeholders, which participle in the financing community safety plans and adminitrative district which are responsible of the transmission of meteorological alert and of rescue actions. In the crossing of the géo-information stemming from the

  14. Stress history and geotechnical properties of sediment from the Cape Fear Diapir, Blake Ridge Diapir, and Blake Ridge

    USGS Publications Warehouse

    Winters, W.J.

    2000-01-01

    Geotechnical properties of sediment from Ocean Drilling Program Leg 164 are presented as: (1) normalized shipboard strength ratios from the Cape Fear Diapir, the Blake Ridge Diapir, and the Blake Ridge; and (2) Atterberg limit, vane shear strength, pocket-penetrometer strength, and constant-rate-of-strain consolidation results from Hole 995A, located on the Blake Ridge. This study was conducted to understand the stress history in a region characterized by high sedimentation rates and the presence of gas hydrates. Collectively, the results indicate that sediment from the Blake Ridge exhibits significant underconsolidated behavior, except near the seafloor. At least 10 m of additional overburden was removed by erosion or mass wasting at Hole 993A on the Cape Fear Diapir, compared to nearby sites.

  15. Periodic Magmatic Events on Slow-Spreading Mid-Ocean Ridges: Evidence from the North Kolbeinsey Ridge, Atlantic.

    NASA Astrophysics Data System (ADS)

    Devey, C. W.; Yeo, I. A.

    2015-12-01

    The majority of the Earth's solid surface is produced by volcanic eruptions at mid-ocean ridges. Slow-spreading mid-ocean ridge eruptions are thought to be characterized by cyclic or periodic volcanism separated by periods of tectonic extension. Here we present high-resolution acoustic sidescan data from the North Kolbeinsey Ridge, a shallow slow-spreading ridge where high glacial and steady post-glacial sedimentation rates allow relative flow ages to be determined using backscatter amplitude as a proxy for sediment thickness and hence age. We identify a suite of young lava flows within the axial valley, suggesting that a significant length of the segment was magmatically active at the same time. This suite of flows represents the largest magmatic event in the last 7 kyr but still do not constitute enough volume to maintain the thickness of seismic layer 2A, suggesting that larger volume, periodic magmatic events are required to maintain crustal thickness.

  16. Characterization plan for the Oak Ridge National Laboratory Area-Wide Groundwater Program, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1994-08-01

    This characterization plan has been developed as part of the U.S. Department of Energy`s (DOE`s) investigation of the Groundwater Operable Unit (GWOU) at Oak Ridge National Laboratory (ORNL) located near Oak Ridge, Tennessee. The first iteration of the characterization plan is intended to serve as a strategy document to guide subsequent GWOU remedial investigations. The plan provides a rationale and organization for groundwater data acquisition, monitoring, and remedial actions to be performed during implementation of environmental restoration activities associated with the ORNL GWOU. It is important to note that the characterization plan for the ORNL GWOU is not a prototypical work plan. As such, remedial investigations will be conducted using annual work plans to manage the work activities, and task reports will be used to document the results of the investigations. Sampling and analysis results will be compiled and reported annually with a review of data relative to risk (screening level risk assessment review) for groundwater. This characterization plan outlines the overall strategy for the remedial investigations and defines tasks that are to be conducted during the initial phase of investigation. This plan is presented with the understanding that more specific addenda to the plan will follow.

  17. Cosmic web reconstruction through density ridges: catalogue

    NASA Astrophysics Data System (ADS)

    Chen, Yen-Chi; Ho, Shirley; Brinkmann, Jon; Freeman, Peter E.; Genovese, Christopher R.; Schneider, Donald P.; Wasserman, Larry

    2016-10-01

    We construct a catalogue for filaments using a novel approach called SCMS (subspace constrained mean shift). SCMS is a gradient-based method that detects filaments through density ridges (smooth curves tracing high-density regions). A great advantage of SCMS is its uncertainty measure, which allows an evaluation of the errors for the detected filaments. To detect filaments, we use data from the Sloan Digital Sky Survey, which consist of three galaxy samples: the NYU main galaxy sample (MGS), the LOWZ sample and the CMASS sample. Each of the three data set covers different redshift regions so that the combined sample allows detection of filaments up to z = 0.7. Our filament catalogue consists of a sequence of two-dimensional filament maps at different redshifts that provide several useful statistics on the evolution cosmic web. To construct the maps, we select spectroscopically confirmed galaxies within 0.050 < z < 0.700 and partition them into 130 bins. For each bin, we ignore the redshift, treating the galaxy observations as a 2-D data and detect filaments using SCMS. The filament catalogue consists of 130 individual 2-D filament maps, and each map comprises points on the detected filaments that describe the filamentary structures at a particular redshift. We also apply our filament catalogue to investigate galaxy luminosity and its relation with distance to filament. Using a volume-limited sample, we find strong evidence (6.1σ-12.3σ) that galaxies close to filaments are generally brighter than those at significant distance from filaments.

  18. Oak Ridge National Laboratory Core Competencies

    SciTech Connect

    Roberto, J.B.; Anderson, T.D.; Berven, B.A.; Hildebrand, S.G.; Hartman, F.C.; Honea, R.B.; Jones, J.E. Jr.; Moon, R.M. Jr.; Saltmarsh, M.J.; Shelton, R.B.

    1994-12-01

    A core competency is a distinguishing integration of capabilities which enables an organization to deliver mission results. Core competencies represent the collective learning of an organization and provide the capacity to perform present and future missions. Core competencies are distinguishing characteristics which offer comparative advantage and are difficult to reproduce. They exhibit customer focus, mission relevance, and vertical integration from research through applications. They are demonstrable by metrics such as level of investment, uniqueness of facilities and expertise, and national impact. The Oak Ridge National Laboratory (ORNL) has identified four core competencies which satisfy the above criteria. Each core competency represents an annual investment of at least $100M and is characterized by an integration of Laboratory technical foundations in physical, chemical, and materials sciences; biological, environmental, and social sciences; engineering sciences; and computational sciences and informatics. The ability to integrate broad technical foundations to develop and sustain core competencies in support of national R&D goals is a distinguishing strength of the national laboratories. The ORNL core competencies are: 9 Energy Production and End-Use Technologies o Biological and Environmental Sciences and Technology o Advanced Materials Synthesis, Processing, and Characterization & Neutron-Based Science and Technology. The distinguishing characteristics of each ORNL core competency are described. In addition, written material is provided for two emerging competencies: Manufacturing Technologies and Computational Science and Advanced Computing. Distinguishing institutional competencies in the Development and Operation of National Research Facilities, R&D Integration and Partnerships, Technology Transfer, and Science Education are also described. Finally, financial data for the ORNL core competencies are summarized in the appendices.

  19. INDEPENDENT VERIFICATION OF THE CENTRAL CAMPUS AND SOUTHEAST LABORATORY COMPLEX BUILDING SLABS AT OAK RIDGE NATIONAL LABORATORY, OAK RIDGE, TENNESSEE

    SciTech Connect

    Weaver, Phyllis C.

    2012-07-24

    Oak Ridge Associated Universities/Oak Ridge Institute for Science and Education (ORAU/ORISE) has completed the independent verification survey of the Central Campus and Southeast Lab Complex Building Slabs. The results of this effort are provided. The objective of this verification survey was to provide independent review and field assessment of remediation actions conducted by SEC, and to independently assess whether the final radiological condition of the slabs met the release guidelines.

  20. Neogene magmatism northeast of the Aegir and Kolbeinsey ridges, NE Atlantic: Spreading ridge-mantle plume interaction?

    NASA Astrophysics Data System (ADS)

    Breivik, AsbjøRn Johan; Faleide, Jan Inge; Mjelde, Rolf

    2008-02-01

    According to mantle plume theory the Earth's interior cools partly by localized large vertical mass transport, causing extensive decompression melting. The Iceland melt anomaly is regarded as a typical example of a mantle plume. However, there are centers of Miocene to recent magmatism in the Norwegian-Greenland Sea not easily explained by the plume theory. Here we present new data to document diffuse late Miocene magmatic underplating of older oceanic crust located mostly north of the Aegir Ridge, an extinct seafloor spreading axis in the Norway Basin. There is also a region with similar magmatism northeast of the presently spreading Kolbeinsey Ridge north of Iceland. Intraplate magmatism in these locations is not easily explained by local plume models, edge-driven convection, or by asthenosphere flow-lithosphere thickness interaction. On the basis of correlation between the magmatism and the active or extinct spreading ridges, we propose the mid-ocean ridge basalt-capture model, in which this magmatism can be understood through plume-spreading ridge interaction: The asthenosphere flow out from Iceland captures deeper, low-degree partially molten asthenospheric regions from underneath the spreading ridges and carry these across the terminating fracture zones, to subsequently underplate oceanic crust or to intrude and build seamounts. This model is similar to lithospheric cracking models for intraplate magmatism in requiring that low-degree partial melt can be retained in the asthenosphere over time but differ in that the magma is extracted by internal magma movement processes and not by external tectonic forces.

  1. RHIC 10 Hz global orbit feedback system

    SciTech Connect

    Michnoff, R.; Arnold, L.; Carboni, L.; Cerniglia, P; Curcio, A.; DeSanto, L.; Folz, C.; Ho, C.; Hoff, L.; Hulsart, R.; Karl, R.; Luo, Y.; Liu, C.; MacKay, W.; Mahler, G.; Meng, W.; Mernick, K.; Minty, M.; Montag, C.; Olsen, R.; Piacentino, J.; Popken, P.; Przybylinski, R.; Ptitsyn, V.; Ritter, J.; Schoenfeld, R.; Thieberger, P.; Tuozzolo, J.; Weston, A.; White, J.; Ziminski, P.; Zimmerman, P.

    2011-03-28

    Vibrations of the cryogenic triplet magnets at the Relativistic Heavy Ion Collider (RHIC) are suspected to be causing the horizontal beam perturbations observed at frequencies around 10 Hz. Several solutions to counteract the effect have been considered in the past, including a local beam feedback system at each of the two experimental areas, reinforcing the magnet base support assembly, and a mechanical servo feedback system. However, the local feedback system was insufficient because perturbation amplitudes outside the experimental areas were still problematic, and the mechanical solutions are very expensive. A global 10 Hz orbit feedback system consisting of 36 beam position monitors (BPMs) and 12 small dedicated dipole corrector magnets in each of the two 3.8 km circumference counter-rotating rings has been developed and commissioned in February 2011. A description of the system architecture and results with beam will be discussed.

  2. The Greenhouse Effect and Climate Feedbacks

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    We review the theory of the greenhouse effect and climate feedback. We also compare the theory with observations, using examples taken from all four known terrestrial worlds with substantial atmospheres: Venus, Earth, Mars, and Titan.

  3. The Greenhouse Effect and Climate Feedbacks

    NASA Astrophysics Data System (ADS)

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

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

  4. Computer automation for feedback system design

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Mathematical techniques and explanations of various steps used by an automated computer program to design feedback systems are summarized. Special attention was given to refining the automatic evaluation suboptimal loop transmission and the translation of time to frequency domain specifications.

  5. Cirrus feedback on interannual climate fluctuations

    SciTech Connect

    Zhou, C.; Dessler, A. E.; Zelinka, M. D.; Yang, P.; Wang, T.

    2014-12-28

    Cirrus clouds are not only important in determining the current climate, but also play an important role in climate change and variability. Analysis of satellite observations shows that the amount and altitude of cirrus clouds (optical depth <3.6, cloud top pressure <440 hPa) increase in response to inter-annual surface warming. Thus, cirrus clouds are likely to act as a positive feedback on short-term climate fluctuations, by reducing the planet’s ability to radiate longwave radiation to space in response to planetary surface warming. Using cirrus cloud radiative kernels, the magnitude of cirrus feedback is estimated to be 0.20±0.21W/m2/°C, which is comparable to the surface albedo feedback. Most of the cirrus feedback comes from increasing cloud amount in the tropical tropopause layer (TTL) and subtropical upper troposphere.

  6. Black-Hole Feedback in Quasars

    NASA Video Gallery

    This animation illustrates how black-hole feedback works in quasars. Dense gas and dust in the center simultaneously fuels the black hole and shrouds it from view. The black-hole wind propels large...

  7. Nonlinear feedback control of multiple robot arms

    NASA Technical Reports Server (NTRS)

    Tarn, T. J.; Yun, X.; Bejczy, A. K.

    1987-01-01

    Multiple coordinated robot arms are modeled by considering the arms: (1) as closed kinematic chains, and (2) as a force constrained mechanical system working on the same object simultaneously. In both formulations a new dynamic control method is discussed. It is based on a feedback linearization and simultaneous output decoupling technique. Applying a nonlinear feedback and a nonlinear coordinate transformation, the complicated model of the multiple robot arms in either formulation is converted into a linear and output decoupled system. The linear system control theory and optimal control theory are used to design robust controllers in the task space. The first formulation has the advantage of automatically handling the coordination and load distribution among the robot arms. In the second formulation, by choosing a general output equation, researchers can superimpose the position and velocity error feedback with the force-torque error feedback in the task space simultaneously.

  8. Use of Feedback in Clinical Prediction

    ERIC Educational Resources Information Center

    Schroeder, Harold E.

    1972-01-01

    Results indicated that predictive accuracy is greater when feedback is applied to the basis for the prediction than when applied to gut" impressions. Judges forming hypotheses were also able to learn from experience. (Author)

  9. Distinguishing Feedback Mechanisms in Clock Models

    NASA Astrophysics Data System (ADS)

    Golden, Alexander; Lubensky, David

    Biological oscillators are very diverse but can be classified based on dynamical motifs such as type of feedback. The S. Elongatus circadian oscillator is a novel circadian oscillator that can operate at constant protein number by modifying covalent states. It can be reproduced in vitro with only 3 different purified proteins: KaiA, KaiB, and KaiC. We use computational and analytic techniques to compare models of the S. Elongatus post-translational oscillator that rely on positive feedback with models that rely on negative feedback. We show that introducing a protein that binds competitively with KaiA to the KaiB-KaiC complex can distinguish between positive and negative feedback as the primary driver of the rhythm, which has so far been difficult to address experimentally. NSF Grant DMR-1056456.

  10. Biased feedback in brain-computer interfaces

    PubMed Central

    2010-01-01

    Even though feedback is considered to play an important role in learning how to operate a brain-computer interface (BCI), to date no significant influence of feedback design on BCI-performance has been reported in literature. In this work, we adapt a standard motor-imagery BCI-paradigm to study how BCI-performance is affected by biasing the belief subjects have on their level of control over the BCI system. Our findings indicate that subjects already capable of operating a BCI are impeded by inaccurate feedback, while subjects normally performing on or close to chance level may actually benefit from an incorrect belief on their performance level. Our results imply that optimal feedback design in BCIs should take into account a subject's current skill level. PMID:20659350

  11. Final report, Feedback limitations of photosynthesis

    SciTech Connect

    Sharkey, Thomas D.

    1999-07-22

    Final report of research on carbon metabolism of photosynthesis. The feedback from carbon metabolism to primary photosynthetic processes is summarized, and a comprehensive list of published scientific papers is provided.

  12. Cirrus feedback on interannual climate fluctuations

    NASA Astrophysics Data System (ADS)

    Zhou, C.; Dessler, A. E.; Zelinka, M. D.; Yang, P.; Wang, T.

    2014-12-01

    Cirrus clouds are not only important in determining the current climate but also play an important role in climate change and variability. Analysis of satellite observations shows that the amount and altitude of cirrus clouds (cloud optical depth < 3.6, cloud top pressure < 440 hPa) increase in response to interannual surface warming. Using cirrus cloud radiative kernels, the magnitude of the interannual cirrus feedback is estimated to be 0.20 ± 0.21 W/m2/°C, which represents an important component of the cloud feedback. Thus, cirrus clouds are likely to act as a positive feedback on interannual climate fluctuations, by reducing the Earth's ability to radiate longwave radiation to space in response to planetary surface warming. Most of the cirrus feedback comes from increasing cloud amount in the tropical tropopause layer (TTL) and subtropical upper troposphere.

  13. Negative feedback system reduces pump oscillations

    NASA Technical Reports Server (NTRS)

    Rosenmann, W.

    1967-01-01

    External negative feedback system counteracts low frequency oscillations in rocket engine propellant pumps. The system uses a control piston to sense pump discharge fluid on one side and a gas pocket on the other.

  14. Different aspects of performance feedback engage different brain areas: disentangling valence and expectancy in feedback processing.

    PubMed

    Ferdinand, Nicola K; Opitz, Bertram

    2014-08-07

    Evaluating the positive and negative outcomes of our behaviour is important for action selection and learning. Such reinforcement learning has been shown to engage a specific neural circuitry including the mesencephalic dopamine system and its target areas, the striatum and medial frontal cortex, especially the anterior cingulate cortex (ACC). An intensively pursued debate regards the prevailing influence of feedback expectancy and feedback valence on the engagement of these two brain regions in reinforcement learning and their respective roles are far from being understood. To this end, we used a time estimation task with three different types of feedback that allows disentangling the effect of feedback valence and expectancy using functional magnetic resonance imaging (fMRI). Our results show greater ACC activation after unexpected positive and unexpected negative feedback than after expected feedback and by this sensitivity to unexpected events in general irrespective of their valence.

  15. Sea ice-albedo climate feedback mechanism

    SciTech Connect

    Schramm, J.L.; Curry, J.A.; Ebert, E.E.

    1995-02-01

    The sea ice-albedo feedback mechanism over the Arctic Ocean multiyear sea ice is investigated by conducting a series of experiments using several one-dimensional models of the coupled sea ice-atmosphere system. In its simplest form, ice-albedo feedback is thought to be associated with a decrease in the areal cover of snow and ice and a corresponding increase in the surface temperature, further decreasing the area cover of snow and ice. It is shown that the sea ice-albedo feedback can operate even in multiyear pack ice, without the disappearance of this ice, associated with internal processes occurring within the multiyear ice pack (e.g., duration of the snow cover, ice thickness, ice distribution, lead fraction, and melt pond characteristics). The strength of the ice-albedo feedback mechanism is compared for several different thermodynamic sea ice models: a new model that includes ice thickness distribution., the Ebert and Curry model, the Mayjut and Untersteiner model, and the Semtner level-3 and level-0 models. The climate forcing is chosen to be a perturbation of the surface heat flux, and cloud and water vapor feedbacks are inoperative so that the effects of the sea ice-albedo feedback mechanism can be isolated. The inclusion of melt ponds significantly strengthens the ice-albedo feedback, while the ice thickness distribution decreases the strength of the modeled sea ice-albedo feedback. It is emphasized that accurately modeling present-day sea ice thickness is not adequate for a sea ice parameterization; the correct physical processes must be included so that the sea ice parameterization yields correct sensitivities to external forcing. 22 refs., 6 figs., 1 tab.

  16. Extra-cavity feedback into unstable resonators.

    PubMed

    Corkum, P B; Baldis, H A

    1979-05-01

    Unstable resonators constructed of totally reflecting optics are particularly sensitive to extra-cavity feedback. This is demonstrated experimentally by reflecting the attenuated output of an injection mode-locked TEA CO(2) laser, fitted with a confocal unstable resonator, back into the laser resonator. Even after attenuation by ~10(6), significant perturbation ( greater, similar10%) could be observed in the temporal characteristics of the output train. A theory of extra-cavity feedback in the geometric limit is presented. PMID:20212847

  17. Feedbacks in human-landscape systems.

    PubMed

    Chin, Anne; Florsheim, Joan L; Wohl, Ellen; Collins, Brian D

    2014-01-01

    This article identifies key questions and challenges for geomorphologists in investigating coupled feedbacks in human-landscape systems. While feedbacks occur in the absence of human influences, they are also altered by human activity. Feedbacks are a key element to understanding human-influenced geomorphic systems in ways that extend our traditional approach of considering humans as unidirectional drivers of change. Feedbacks have been increasingly identified in Earth-environmental systems, with studies of coupled human-natural systems emphasizing ecological phenomena in producing emerging concepts for social-ecological systems. Enormous gaps or uncertainties in knowledge remain with respect to understanding impact-feedback loops within geomorphic systems with significant human alterations, where the impacted geomorphic systems in turn affect humans. Geomorphology should play an important role in public policy by identifying the many diffuse and subtle feedbacks of both local- and global-scale processes. This role is urgent, while time may still be available to mitigate the impacts that limit the sustainability of human societies. Challenges for geomorphology include identification of the often weak feedbacks that occur over varied time and space scales ranging from geologic time to single isolated events and very short time periods, the lack of available data linking impact with response, the identification of multiple thresholds that trigger feedback mechanisms, the varied tools and metrics needed to represent both physical and human processes, and the need to collaborate with social scientists with expertise in the human causes of geomorphic change, as well as the human responses to such change. PMID:23592016

  18. Herbivory and Stoichiometric Feedbacks to Primary Production.

    PubMed

    Krumins, Jennifer Adams; Krumins, Valdis; Forgoston, Eric; Billings, Lora; van der Putten, Wim H

    2015-01-01

    Established theory addresses the idea that herbivory can have positive feedbacks on nutrient flow to plants. Positive feedbacks likely emerge from a greater availability of organic carbon that primes the soil by supporting nutrient turnover through consumer and especially microbially-mediated metabolism in the detrital pool. We developed an entirely novel stoichiometric model that demonstrates the mechanism of a positive feedback. In particular, we show that sloppy or partial feeding by herbivores increases detrital carbon and nitrogen allowing for greater nitrogen mineralization and nutritive feedback to plants. The model consists of differential equations coupling flows among pools of: plants, herbivores, detrital carbon and nitrogen, and inorganic nitrogen. We test the effects of different levels of herbivore grazing completion and of the stoichiometric quality (carbon to nitrogen ratio, C:N) of the host plant. Our model analyses show that partial feeding and plant C:N interact because when herbivores are sloppy and plant biomass is diverted to the detrital pool, more mineral nitrogen is available to plants because of the stoichiometric difference between the organisms in the detrital pool and the herbivore. This model helps to identify how herbivory may feedback positively on primary production, and it mechanistically connects direct and indirect feedbacks from soil to plant production.

  19. Herbivory and Stoichiometric Feedbacks to Primary Production.

    PubMed

    Krumins, Jennifer Adams; Krumins, Valdis; Forgoston, Eric; Billings, Lora; van der Putten, Wim H

    2015-01-01

    Established theory addresses the idea that herbivory can have positive feedbacks on nutrient flow to plants. Positive feedbacks likely emerge from a greater availability of organic carbon that primes the soil by supporting nutrient turnover through consumer and especially microbially-mediated metabolism in the detrital pool. We developed an entirely novel stoichiometric model that demonstrates the mechanism of a positive feedback. In particular, we show that sloppy or partial feeding by herbivores increases detrital carbon and nitrogen allowing for greater nitrogen mineralization and nutritive feedback to plants. The model consists of differential equations coupling flows among pools of: plants, herbivores, detrital carbon and nitrogen, and inorganic nitrogen. We test the effects of different levels of herbivore grazing completion and of the stoichiometric quality (carbon to nitrogen ratio, C:N) of the host plant. Our model analyses show that partial feeding and plant C:N interact because when herbivores are sloppy and plant biomass is diverted to the detrital pool, more mineral nitrogen is available to plants because of the stoichiometric difference between the organisms in the detrital pool and the herbivore. This model helps to identify how herbivory may feedback positively on primary production, and it mechanistically connects direct and indirect feedbacks from soil to plant production. PMID:26098841

  20. Remote feedback stabilization of tokamak instabilities

    SciTech Connect

    Sen, A.K. )

    1994-05-01

    A novel remote suppressor consisting of an injected ion beam has been used for the stabilization of plasma instabilities. A collisionless curvature-driven trapped-particle instability, an [bold E][times][bold B] flute mode and an ion temperature gradient (ITG) instability have been successfully suppressed down to noise levels using this scheme. Furthermore, the first experimental demonstration of a multimode feedback stabilization with a single sensor--suppressor pair has been achieved. Two modes (an [bold E][times][bold B] flute and an ITG mode) were simultaneously stabilized with a simple state-feedback-type method where more state'' information was generated from a single-sensor Langmuir probe by appropriate signal processing. The above experiments may be considered as paradigms for controlling several important tokamak instabilities. First, feedback suppression of edge fluctuations in a tokamak with a suitable form of insulated segmented poloidal limiter sections used as Langmuir-probe-like suppressors is proposed. Other feedback control schemes are proposed for the suppression of electrostatic core fluctuations via appropriately phased ion density input from a modulated neutral beam. Most importantly, a scheme to control major disruptions in tokamaks via feedback suppression of kink (and possibly) tearing modes is discussed. This may be accomplished by using a modulated neutral beam suppressor in a feedback loop, which will supply a momentum input of appropriate phase and amplitude. Simple theoretical models predict modest levels of beam energy, current, and power.