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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  3. 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.

  4. 1.55μm laterally coupled ridge-waveguide DFB lasers with third-order surface grating

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    Laterally-coupled distributed feedback (LC-DFB) lasers offer compelling advantages over standard DFB lasers. The use of surface grating on the ridge waveguide sidewalls in LC-DFB devices avoids any epitaxial overgrowth. This provides a considerable simplification in the fabrication process, reducing cost and time of manufacturing, and ultimately increasing yield. It offers also the potential for monolithic integration with other devices; paving the way towards low-cost and mass-production of photonics integrated circuits. In this work, we report on the realization of high-order grating InGaAsP/InP multiple-quantum-well (MQW) LC-DFB lasers at 1.55 μm by means of stepper lithography and inductively-coupled reactive-ion as well as wet chemical etching. Third-order rectangular-shaped grating has been lithographically defined on the ridge waveguide sidewalls with a relatively deep etching along the laser cavity. The preliminary experimental characterization shows interesting results for as-cleaved devices tested in room temperature under CW operation. A fabricated 1500 μm-long cavity LC-DFB laser shows stable single-mode operation with a side mode suppression ratio as high as 50 dB. The tested device can emit at power as high as 9 mW, and the measured threshold current is around 80 mA at room temperature. Moreover, the measured linewidth has been found to be as narrow as 178 kHz using the delayed self-heterodyne interferometric technique.

  5. 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).

  6. Laterally coupled distributed feedback lasers emitting at 2 μm with quantum dash active region and high-duty-cycle etched semiconductor gratings

    NASA Astrophysics Data System (ADS)

    Papatryfonos, Konstantinos; Saladukha, Dzianis; Merghem, Kamel; Joshi, Siddharth; Lelarge, Francois; Bouchoule, Sophie; Kazazis, Dimitrios; Guilet, Stephane; Le Gratiet, Luc; Ochalski, Tomasz J.; Huyet, Guillaume; Martinez, Anthony; Ramdane, Abderrahim

    2017-02-01

    Single-mode diode lasers on an InP(001) substrate have been developed using InAs/In0.53Ga0.47As quantum dash (Qdash) active regions and etched lateral Bragg gratings. The lasers have been designed to operate at wavelengths near 2 μm and exhibit a threshold current of 65 mA for a 600 μm long cavity, and a room temperature continuous wave output power per facet >5 mW. Using our novel growth approach based on the low ternary In0.53Ga0.47As barriers, we also demonstrate ridge-waveguide lasers emitting up to 2.1 μm and underline the possibilities for further pushing the emission wavelength out towards longer wavelengths with this material system. By introducing experimentally the concept of high-duty-cycle lateral Bragg gratings, a side mode suppression ratio of >37 dB has been achieved, owing to an appreciably increased grating coupling coefficient of κ ˜ 40 cm-1. These laterally coupled distributed feedback (LC-DFB) lasers combine the advantage of high and well-controlled coupling coefficients achieved in conventional DFB lasers, with the regrowth-free fabrication process of lateral gratings, and exhibit substantially lower optical losses compared to the conventional metal-based LC-DFB lasers.

  7. 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.

  8. Ridge Polynomial Neural Network with Error Feedback for Time Series Forecasting.

    PubMed

    Waheeb, Waddah; Ghazali, Rozaida; Herawan, Tutut

    2016-01-01

    Time series forecasting has gained much attention due to its many practical applications. Higher-order neural network with recurrent feedback is a powerful technique that has been used successfully for time series forecasting. It maintains fast learning and the ability to learn the dynamics of the time series over time. Network output feedback is the most common recurrent feedback for many recurrent neural network models. However, not much attention has been paid to the use of network error feedback instead of network output feedback. In this study, we propose a novel model, called Ridge Polynomial Neural Network with Error Feedback (RPNN-EF) that incorporates higher order terms, recurrence and error feedback. To evaluate the performance of RPNN-EF, we used four univariate time series with different forecasting horizons, namely star brightness, monthly smoothed sunspot numbers, daily Euro/Dollar exchange rate, and Mackey-Glass time-delay differential equation. We compared the forecasting performance of RPNN-EF with the ordinary Ridge Polynomial Neural Network (RPNN) and the Dynamic Ridge Polynomial Neural Network (DRPNN). Simulation results showed an average 23.34% improvement in Root Mean Square Error (RMSE) with respect to RPNN and an average 10.74% improvement with respect to DRPNN. That means that using network errors during training helps enhance the overall forecasting performance for the network.

  9. Ridge Polynomial Neural Network with Error Feedback for Time Series Forecasting

    PubMed Central

    Ghazali, Rozaida; Herawan, Tutut

    2016-01-01

    Time series forecasting has gained much attention due to its many practical applications. Higher-order neural network with recurrent feedback is a powerful technique that has been used successfully for time series forecasting. It maintains fast learning and the ability to learn the dynamics of the time series over time. Network output feedback is the most common recurrent feedback for many recurrent neural network models. However, not much attention has been paid to the use of network error feedback instead of network output feedback. In this study, we propose a novel model, called Ridge Polynomial Neural Network with Error Feedback (RPNN-EF) that incorporates higher order terms, recurrence and error feedback. To evaluate the performance of RPNN-EF, we used four univariate time series with different forecasting horizons, namely star brightness, monthly smoothed sunspot numbers, daily Euro/Dollar exchange rate, and Mackey-Glass time-delay differential equation. We compared the forecasting performance of RPNN-EF with the ordinary Ridge Polynomial Neural Network (RPNN) and the Dynamic Ridge Polynomial Neural Network (DRPNN). Simulation results showed an average 23.34% improvement in Root Mean Square Error (RMSE) with respect to RPNN and an average 10.74% improvement with respect to DRPNN. That means that using network errors during training helps enhance the overall forecasting performance for the network. PMID:27959927

  10. 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.

  11. 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

  12. 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.

  13. Metopic ridge

    MedlinePlus

    ... 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 ...

  14. 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…

  15. Ridge suction drives plume-ridge interactions

    NASA Astrophysics Data System (ADS)

    Niu, Y.; Hékinian, R.

    2003-04-01

    Deep-sourced mantle plumes, if existing, are genetically independent of plate tectonics. When the ascending plumes approach lithospheric plates, interactions between the two occur. Such interactions are most prominent near ocean ridges where the lithosphere is thin and the effect of plumes is best revealed. While ocean ridges are mostly passive features in terms of plate tectonics, they play an active role in the context of plume-ridge interactions. This active role is a ridge suction force that drives asthenospheric mantle flow towards ridges because of material needs to form the ocean crust at ridges and lithospheric mantle in the vicinity of ridges. This ridge suction force increases with increasing plate separation rate because of increased material demand per unit time. As the seismic low-velocity zone atop the asthenosphere has the lowest viscosity that increases rapidly with depth, the ridge-ward asthenospheric flow is largely horizontal beneath the lithosphere. Recognizing that plume materials have two components with easily-melted dikes/veins enriched in volatiles and incompatible elements dispersed in the more refractory and depleted peridotitic matrix, geochemistry of some seafloor volcanics well illustrates that plume-ridge interactions are consequences of ridge-suction-driven flow of plume materials, which melt by decompression because of lithospheric thinning towards ridges. There are excellent examples: 1. The decreasing La/Sm and increasing MgO and CaO/Al_2O_3 in Easter Seamount lavas from Salas-y-Gomez Islands to the Easter Microplate East rift zone result from progressive decompression melting of ridge-ward flowing plume materials. 2. The similar geochemical observations in lavas along the Foundation hotline towards the Pacific-Antarctic Ridge result from the same process. 3. The increasing ridge suction force with increasing spreading rate explains why the Iceland plume has asymmetric effects on its neighboring ridges: both topographic and

  16. Ridge Regression: A Panacea?

    ERIC Educational Resources Information Center

    Walton, Joseph M.; And Others

    1978-01-01

    Ridge regression is an approach to the problem of large standard errors of regression estimates of intercorrelated regressors. The effect of ridge regression on the estimated squared multiple correlation coefficient is discussed and illustrated. (JKS)

  17. 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

  18. Feedback & Objectives

    ERIC Educational Resources Information Center

    Butterworth, James R.

    1975-01-01

    Industrial objectives, if they are employee oriented, produce feedback, and the motivation derived from the feedback helps reduce turnover. Feedback is the power to clarify objectives, to stimulate communication, and to motivate people. (Author/MW)

  19. 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.

  20. 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.

  1. Calculating a Stepwise Ridge Regression.

    ERIC Educational Resources Information Center

    Morris, John D.

    1986-01-01

    Although methods for using ordinary least squares regression computer programs to calculate a ridge regression are available, the calculation of a stepwise ridge regression requires a special purpose algorithm and computer program. The correct stepwise ridge regression procedure is given, and a parallel FORTRAN computer program is described.…

  2. Data Management for the Ridge 2000 Program

    NASA Astrophysics Data System (ADS)

    Chayes, D. N.; Robert, A. A.; Carbotte, S. M.; Ryan, W. B.; Lenhert, K. A.; Shank, T. M.

    2004-12-01

    Since the start of this effort (September 1, 2003) we have developed a data base schema, selected and installed a relational data base management system (PostgreSQL), designed, developed and, deployed a draft set of metadata forms, ingested data from ten Ridge2000 cruises as of September 2004 and deployed a web accessible Ridge2000 data portal: http://www.marine-geo.org/ridge2000/ . At the portal, one can get content using with pre-constructed queries for survey targets and deployed instruments at each of the R2K Integrated Study Sites. Alternatively, our data link allows spatial, temporal and keyword searches to identify and download data. The current metadata forms have been used for 6 cruises and we have received constructive feedback (in addition to the actual metadata) from all three R2K integrated study sites. We are working on incorporating this feedback into an updated set of forms which we expect to release early in 2005. Other recent include substantial improvements to GeoMapApp, links to other data repositories, a major update of our web site, integration with data from Arctic, Antarctic, Margins data sets and the pre-constructed queries on the R2K portal page. Our plans for 2005 include: A second major revision of the metadata forms in early '05, improvements in the metadata ingestion process, enhanced authentication using LDAP, continued active participation in the broader data community developing interoperability as well as implementing direct interoperability with a number of complementary databases including the underway geophysical and multibeam databases at National Geophysical Data Center, the National Deep Submergence facility at Woods Hole, the Geological Data Center of the Scripps Institute of Oceanography, and the databases of the ODP (JANUS at TAMU, and Borehole Geophysics at LDEO)

  3. Ridge regression processing

    NASA Technical Reports Server (NTRS)

    Kuhl, Mark R.

    1990-01-01

    Current navigation requirements depend on a geometric dilution of precision (GDOP) criterion. As long as the GDOP stays below a specific value, navigation requirements are met. The GDOP will exceed the specified value when the measurement geometry becomes too collinear. A new signal processing technique, called Ridge Regression Processing, can reduce the effects of nearly collinear measurement geometry; thereby reducing the inflation of the measurement errors. It is shown that the Ridge signal processor gives a consistently better mean squared error (MSE) in position than the Ordinary Least Mean Squares (OLS) estimator. The applicability of this technique is currently being investigated to improve the following areas: receiver autonomous integrity monitoring (RAIM), coverage requirements, availability requirements, and precision approaches.

  4. 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

  5. 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

  6. Feedback: Breakfast of Champions.

    ERIC Educational Resources Information Center

    Justman, Jeffrey J.

    Feedback is an important skill that people need to learn in life. Feedback is crucial in a public speaking class to improve speaking skills. Providing and receiving feedback is what champions feed on to be successful, thus feedback is called the "Breakfast of Champions." Feedback builds speakers' confidence. Providing in-depth feedback…

  7. 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)

  8. 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.

  9. Repeat ridge jumps associated with plume-ridge interaction, melt transport, and ridge migration

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, Eric; Ito, Garrett; van Hunen, Jeroen

    2011-01-01

    Repeated shifts, or jumps, of mid-ocean ridge segments toward nearby hot spots can produce large, long-term changes to the geometry and location of the tectonic plate boundaries. Ridge jumps associated with hot spot-ridge interaction are likely caused by several processes including shear on the base of the plate due to expanding plume material as well as reheating of lithosphere as magma passes through it to feed off-axis volcanism. To study how these processes influence ridge jumps, we use numerical models to simulate 2-D (in cross section) viscous flow of the mantle, viscoplastic deformation of the lithosphere, and melt migration upward from the asthenospheric melting zone, laterally along the base of the lithosphere, and vertically through the lithosphere. The locations and rates that magma penetrates and heats the lithosphere are controlled by the time-varying accumulation of melt beneath the plate and the depth-averaged lithospheric porosity. We examine the effect of four key parameters: magmatic heating rate of the lithosphere, plate spreading rate, age of the seafloor overlying the plume, and the plume-ridge migration rate. Results indicate that the minimum value of the magmatic heating rate needed to initiate a ridge jump increases with plate age and spreading rate. The time required to complete a ridge jump decreases with larger values of magmatic heating rate, younger plate age, and faster spreading rate. For cases with migrating ridges, models predict a range of behaviors including repeating ridge jumps, much like those exhibited on Earth. Repeating ridge jumps occur at moderate magmatic heating rates and are the result of changes in the hot spot magma flux in response to magma migration along the base of an evolving lithosphere. The tendency of slow spreading to promote ridge jumps could help explain the observed clustering of hot spots near the Mid-Atlantic Ridge. Model results also suggest that magmatic heating may significantly thin the lithosphere

  10. Sinuous Ridges in Peta Crater, Mars

    NASA Astrophysics Data System (ADS)

    Parker, T. J.

    2011-03-01

    Peta Crater (21°S,351°E) contains a system of sinuous ridges similar to, but smaller than, the well-known Dorsa Argyre and Dorsa Argentea ridges. Recent CTX and HiRISE images of the Peta crater ridges is enabling a detailed examination of this confined system of ridges.

  11. 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

  12. Inactive tanks remediation program strategy and plans for Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1997-03-01

    This report presents plans and strategies for remediation of the liquid low-level waste (LLLW) tanks that have been removed from service (also known as inactive tanks) at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. These plans and strategies will be carried out by the Environmental Restoration Program`s Inactive LLLW Tank Program at ORNL. These tanks are defined as Category D tanks because they are existing tank systems without secondary containment that are removed from service. The approach to remediation of each tank or tank farm must be adapted in response to the specific circumstances of individual tank sites. The approach will be tailored to accommodate feedback on lessons learned from previous tank remediation activities and will not be a rigid step-by-step approach that must be conducted identically for every tank system. However, the approach will follow a multistep decision process. The overall objective of the Inactive Tank Program is to remediate all LLLW tanks that have been removed from service to the extent practicable in accordance with the FFA requirements. The Inactive Tank Program will focus on the remediation of the tank residues (i.e., contents after tank has been emptied) and tank shell. This strategy is discussed in detail in this report.

  13. Inactive tanks remediation program strategy and plans for Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1997-11-01

    This report presents plans and strategies for remediation of the liquid low-level waste (LLLW) tanks that have been removed from service (also known as inactive tanks) at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. These plans and strategies will be carried out by the Environmental Restoration Program`s Inactive LLLW Tank Program at ORNL. The approach to remediation of each tank or tank farm must be adapted in response to the specific circumstances of individual tank sites. The approach will be tailored to accommodate feedback on lessons learned from previous tank remediation activities and will not be a rigid step-by-step approach that must be conducted identically for every tank system. However, the approach will follow a multistep decision process. The overall objective of the Inactive Tank Program is to remediate all LLLW tanks that have been removed from service to the extent practicable in accordance with the FFA requirements. The Inactive Tank Program will focus on the remediation of the tank residues and tank shell. This strategy is discussed in detail in this report.

  14. 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…

  15. 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.

  16. HIGHLAND RIDGE ROADLESS AREA, NEVADA.

    USGS Publications Warehouse

    Whitebread, Donald H.; Brown, S. Don

    1984-01-01

    The mineral-resource potential of the Highland Ridge Roadless Area, Nevada was evaluated on the basis of results from field investigations. One area along the west border of the Highland Ridge Roadless Area has substantiated mineral-resource potential for tungsten. Several other areas are classed as having probable mineral-resource potential, based mainly upon anomalously high values of tungsten, lead, silver, and zinc in concentrates of stream sediments. Most of the roadless area is underlain by rocks in the upper plate of the Snake Range decollement, and is considered to have little promise for the occurrence of mineral resources. No energy resource potential was identified in the area.

  17. THE EQUATION AT OAK RIDGE.

    ERIC Educational Resources Information Center

    MORRELL, KEN

    THE STEPS TAKEN TO DESEGREGATE THE OAK RIDGE, TENN., SCHOOLS ARE DESCRIBED IN THIS ARTICLE. ONE ELEMENTARY SCHOOL, SEGREGATED BECAUSE OF RESIDENTIAL PATTERNS, WAS CLOSED AND ITS STUDENTS REDISTRIBUTED AMONG OTHER SCHOOLS IN THE CITY. UNDER THE INITIATIVE OF THE SCHOOL BOARD, THIS PLAN WENT INTO EFFECT IN THE FALL OF 1967 AND IS SAID TO HAVE…

  18. Improved feedback shift register

    NASA Technical Reports Server (NTRS)

    Perlman, M.

    1972-01-01

    Design of feedback shift register with three tap feedback decoding scheme is described. Application for obtaining sequence synchronization patterns is examined. Operation of the circuitry is described and drawings of the systems are included.

  19. 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…

  20. 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…

  1. Passage Feedback with IRIS.

    ERIC Educational Resources Information Center

    Yang, Kiduk; Maglaughlin, Kelly L.; Newby, Gregory B.

    2001-01-01

    Compares a user-defined passage feedback system to a document feedback system for information retrieval, based on TREC (Text Retrieval Conference) guidelines. Highlights include a description of IRIS, an interactive retrieval system; text processing; ranking; term weights; feedback models, including the adaptive linear model; and suggestions for…

  2. 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…

  3. 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.

  4. 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.

  5. 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.

  6. Hydrologic controls on aperiodic spatial organization of the ridge-slough patterned landscape

    NASA Astrophysics Data System (ADS)

    Casey, Stephen T.; Cohen, Matthew J.; Acharya, Subodh; Kaplan, David A.; Jawitz, James W.

    2016-11-01

    A century of hydrologic modification has altered the physical and biological drivers of landscape processes in the Everglades (Florida, USA). Restoring the ridge-slough patterned landscape, a dominant feature of the historical system, is a priority but requires an understanding of pattern genesis and degradation mechanisms. Physical experiments to evaluate alternative pattern formation mechanisms are limited by the long timescales of peat accumulation and loss, necessitating model-based comparisons, where support for a particular mechanism is based on model replication of extant patterning and trajectories of degradation. However, multiple mechanisms yield a central feature of ridge-slough patterning (patch elongation in the direction of historical flow), limiting the utility of that characteristic for discriminating among alternatives. Using data from vegetation maps, we investigated the statistical features of ridge-slough spatial patterning (ridge density, patch perimeter, elongation, patch size distributions, and spatial periodicity) to establish more rigorous criteria for evaluating model performance and to inform controls on pattern variation across the contemporary system. Mean water depth explained significant variation in ridge density, total perimeter, and length : width ratios, illustrating an important pattern response to existing hydrologic gradients. Two independent analyses (2-D periodograms and patch size distributions) provide strong evidence against regular patterning, with the landscape exhibiting neither a characteristic wavelength nor a characteristic patch size, both of which are expected under conditions that produce regular patterns. Rather, landscape properties suggest robust scale-free patterning, indicating genesis from the coupled effects of local facilitation and a global negative feedback operating uniformly at the landscape scale. Critically, this challenges widespread invocation of scale-dependent negative feedbacks for explaining

  7. Mechanisms of Basalt-plains Ridge Formation

    NASA Technical Reports Server (NTRS)

    Watters, T. R.; Maxwell, T. A.

    1985-01-01

    The morphologic similarities between the Columbia Plateau ridges and ridges on the Moon, Mercury and Mars form a strong basis for the interpretation of basalt-plains ridges as compressional folds. The basalt-plains ridges appear to have formed on competent flood basalt units deformed at the surface with essentially no confining pressure. Estimates of compressive strain for planetary ridges range from a few tenths of a percent on the Moon to up to 0.4% on Mars, to as high as 35% for Columbia Plateau folds with associated thrust faults. Such values have strong implications for both deformational mechanisms as well as for the source of stress. Deformational mechanisms that will attempt to account for the morphology, fold geometry, possible associated thrust faulting and regular spacing of the basalt-plains ridges on the terrestrial planets are under investigation.

  8. Constitutive Parameter Measurement Using Double Ridge Waveguide

    DTIC Science & Technology

    2013-03-01

    CONSTITUTIVE PARAMETER MEASUREMENT USING DOUBLE RIDGE WAVEGUIDE THESIS Nathan J. Lehman, Captain, USAF AFIT-ENG-13-M-30 DEPARTMENT OF THE AIR FORCE...copyright protection in the United States. AFIT-ENG-13-M-30 CONSTITUTIVE PARAMETER MEASUREMENT USING DOUBLE RIDGE WAVEGUIDE THESIS Presented to the Faculty...PARAMETER MEASUREMENT USING DOUBLE RIDGE WAVEGUIDE Nathan J. Lehman, B.S.E.E. Captain, USAF Approved: Michael Havrilla, PhD (Chairman) Maj Milo Hyde, PhD

  9. 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.

  10. 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.

  11. 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.

  12. "Feedback" For Instructioal Television.

    ERIC Educational Resources Information Center

    Schramm, Wilbur

    A number of different methods have been used by instructional television (ITV) projects to obtain audience feedback, and some of these are now being used in the ITV system in El Salvador. We know that pretesting programs on a representative sample can bring considerable gains in learning. Another feedback source can be a classroom of pupils in the…

  13. Convolution feedback systems.

    NASA Technical Reports Server (NTRS)

    Desoer, C. A.; Callier, F. M.

    1972-01-01

    Linear time-invariant feedback systems with multiple inputs and multiple outputs are examined. It is demonstrated that no loss of generality takes place considering the feedback to be unity. Necessary and sufficient conditions are derived for the closed-loop impulse response to be stable in a prescribed sense.

  14. 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.

  15. Student Health Services at Orchard Ridge.

    ERIC Educational Resources Information Center

    Nichols, Don D.

    This paper provides a synoptic review of student health services at the community college level while giving a more detailed description of the nature of health services at Orchard Ridge, a campus of Oakland Community College. The present College Health Service program provides for a part-time (24 hrs./wk.) nurse at Orchard Ridge. A variety of…

  16. 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.

  17. Tectonics and magmatism of ultraslow spreading ridges

    NASA Astrophysics Data System (ADS)

    Dubinin, E. P.; Kokhan, A. V.; Sushchevskaya, N. M.

    2013-05-01

    The tectonics, structure-forming processes, and magmatism in rift zones of ultraslow spreading ridges are exemplified in the Reykjanes, Kolbeinsey, Mohns, Knipovich, Gakkel, and Southwest Indian ridges. The thermal state of the mantle, the thickness of the brittle lithospheric layer, and spreading obliquety are the most important factors that control the structural pattern of rift zones. For the Reykjanes and Kolbeinsey ridges, the following are crucial factors: variations in the crust thickness; relationships between the thicknesses of its brittle and ductile layers; width of the rift zone; increase in intensity of magma supply approaching the Iceland thermal anomaly; and spreading obliquety. For the Knipovich Ridge, these are its localization in the transitional zone between the Gakkel and Mohns ridges under conditions of shear and tensile stresses and multiple rearrangements of spreading; nonorthogonal spreading; and structural and compositional barrier of thick continental lithosphere at the Barents Sea shelf and Spitsbergen. The Mohns Ridge is characterized by oblique spreading under conditions of a thick cold lithosphere and narrow stable rift zone. The Gakkel and the Southwest Indian ridges are distinguished by the lowest spreading rate under the settings of the along-strike variations in heating of the mantle and of a variable spreading geometry. The intensity of endogenic structure-forming varies along the strike of the ridges. In addition to the prevalence of tectonic factors in the formation of the topography, magmatism and metamorphism locally play an important role.

  18. 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…

  19. 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

  20. 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.

  1. 1. GENERAL VIEW OF ENTRANCE TO BLUE RIDGE TUNNEL (LEFT) ...

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

    1. GENERAL VIEW OF ENTRANCE TO BLUE RIDGE TUNNEL (LEFT) FROM SOUTHEAST. ORIGINAL BLUE RIDGE R.R. (CROZET) TUNNEL IS VISIBLE AT RIGHT. - Chesapeake & Ohio Railroad, Blue Ridge Tunnel, Highway 250 at Rockfish Gap, Afton, Nelson County, VA

  2. Plume-ridge interaction: Shaping the geometry of mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, Eric L.

    Manifestations of plume-ridge interaction are found across the ocean basins. Currently there are interactions between at least 21 hot spots and nearby ridges along 15--20% of the global mid-ocean ridge network. These interactions produce a number of anomalies including the presence of elevated topography, negative gravity anomalies, and anomalous crustal production. One form of anomalous crustal production is the formation of volcanic lineaments between hotspots and nearby mid-ocean ridges. In addition, observations indicate that mantle plumes tend to "capture" nearby mid-ocean ridges through asymmetric spreading, increased ridge propagation, and discrete shifts of the ridge axis, or ridge jumps. The initiation of ridge jumps and the formation of off-axis volcanic lineaments likely involve similar processes and may be closely related. In the following work, I use theoretical and numerical models to quantify the processes that control the formation of volcanic lineaments (Chapter 2), the initiation of mid-ocean ridge jumps associated with lithospheric heating due to magma passing through the plate (Chapter 3), and the initiation of jumps due to an upwelling mantle plume and magmatic heating governed by melt migration (Chapter 4). Results indicate that lineaments and ridge jumps associated with plume-ridge interaction are most likely to occur on young lithosphere. The shape of lineaments on the seafloor is predicted to be controlled by the pattern of lithospheric stresses associated with a laterally spreading, near-ridge mantle plume. Ridge jumps are likely to occur due to magmatic heating alone only in lithosphere ˜1Myr old, because the heating rate required to jump increases with spreading rate and plate age. The added effect of an upwelling plume introduces competing effects that both promote and inhibit ridge jumps. For models where magmatic heating is controlled by melt migration, repeat ridge jumps are predicted to occur as the plume and ridge separate, but

  3. 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.

  4. 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

  5. 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.

  6. On Gaussian feedback capacity

    NASA Technical Reports Server (NTRS)

    Dembo, Amir

    1989-01-01

    Pinsker and Ebert (1970) proved that in channels with additive Gaussian noise, feedback at most doubles the capacity. Cover and Pombra (1989) proved that feedback at most adds half a bit per transmission. Following their approach, the author proves that in the limit as signal power approaches either zero (very low SNR) or infinity (very high SNR), feedback does not increase the finite block-length capacity (which for nonstationary Gaussian channels replaces the standard notion of capacity that may not exist). Tighter upper bounds on the capacity are obtained in the process. Specializing these results to stationary channels, the author recovers some of the bounds recently obtained by Ozarow.

  7. Stratospheric water vapor feedback.

    PubMed

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

    2013-11-05

    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.

  8. Feedback valence affects auditory perceptual learning independently of feedback probability.

    PubMed

    Amitay, Sygal; Moore, David R; Molloy, Katharine; Halliday, Lorna F

    2015-01-01

    Previous studies have suggested that negative feedback is more effective in driving learning than positive feedback. We investigated the effect on learning of providing varying amounts of negative and positive feedback while listeners attempted to discriminate between three identical tones; an impossible task that nevertheless produces robust learning. Four feedback conditions were compared during training: 90% positive feedback or 10% negative feedback informed the participants that they were doing equally well, while 10% positive or 90% negative feedback informed them they were doing equally badly. In all conditions the feedback was random in relation to the listeners' responses (because the task was to discriminate three identical tones), yet both the valence (negative vs. positive) and the probability of feedback (10% vs. 90%) affected learning. Feedback that informed listeners they were doing badly resulted in better post-training performance than feedback that informed them they were doing well, independent of valence. In addition, positive feedback during training resulted in better post-training performance than negative feedback, but only positive feedback indicating listeners were doing badly on the task resulted in learning. As we have previously speculated, feedback that better reflected the difficulty of the task was more effective in driving learning than feedback that suggested performance was better than it should have been given perceived task difficulty. But contrary to expectations, positive feedback was more effective than negative feedback in driving learning. Feedback thus had two separable effects on learning: feedback valence affected motivation on a subjectively difficult task, and learning occurred only when feedback probability reflected the subjective difficulty. To optimize learning, training programs need to take into consideration both feedback valence and probability.

  9. 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

  10. Ambulatory Feedback System

    NASA Technical Reports Server (NTRS)

    Finger, Herbert; Weeks, Bill

    1985-01-01

    This presentation discusses instrumentation that will be used for a specific event, which we hope will carry on to future events within the Space Shuttle program. The experiment is the Autogenic Feedback Training Experiment (AFTE) scheduled for Spacelab 3, currently scheduled to be launched in November, 1984. The objectives of the AFTE are to determine the effectiveness of autogenic feedback in preventing or reducing space adaptation syndrome (SAS), to monitor and record in-flight data from the crew, to determine if prediction criteria for SAS can be established, and, finally, to develop an ambulatory instrument package to mount the crew throughout the mission. The purpose of the Ambulatory Feedback System (AFS) is to record the responses of the subject during a provocative event in space and provide a real-time feedback display to reinforce the training.

  11. 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.

  12. 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

  13. West Chestnut Ridge hydrologic studies

    SciTech Connect

    Elmore, J.L.; Huff, D.D.; Jones, J.R.

    1985-08-01

    Preliminary site characterization work for the proposed West Chestnut Ridge Central Waste Disposal Facility included collection and analysis of data on stream flows, watershed areas, precipitation, water levels at piezometer sites, and physiochemical properties of surface water. Seven temporary water-flow-gaging installations were established and used to characterize runoff patterns in the study area. Chip-floating and regression techniques were used to estimate stream flows after some of the temporary structures were destroyed during high flows. Stream flow fluctuations were quantified using coefficients of variation and percent change in total flow between adjacent sampling dates. The difference between precipitation and observed flows (net loss) was calculated for all stations. Two headwater stations (4 and 6) exhibited lower flows per watershed area and channel length, and higher levels of fluctuation in flow than the other stations. These two stations were also similar in watershed area and flow magnitude. Two other headwater stations (5 and 7) with comparable flows had total drainage areas that were similar in size and smaller than those of the other stations. Stations 5 and 7 exhibited high flows per drainage area and section length, especially in the dry period of the year when flows were higher than at all other stations. Fluctuations in flows were lowest at these two stations. Data indicate that these two sections are fed by sources of dependable groundwater. 7 refs., 4 figs., 8 tabs.

  14. Low Sun from 'Low Ridge'

    NASA Technical Reports Server (NTRS)

    2006-01-01

    A spectacular field of Martian sand ripples separates NASA's Mars Exploration Rover Spirit from the slopes of 'Husband Hill.' It has been 200 Martian days, or sols, since the rover started a descent from the top of the peak to the rover's current position on 'Low Ridge.' Looking back to the north on sol 813 (April 17, 2006), Spirit acquired this blue-filter (436-nanometer) view with the right panoramic camera (Pancam) while the Sun was low in the sky late in the afternoon. Because of the low-angle lighting (sunlight is coming from the left), images like this provide superb views of subtle textures in the topography both near and far. Husband Hill, where the rover was perched late last summer, rises prominently just left of center in this view. A 150-meter wide (500 foot) field of curving sand ripples named 'El Dorado' lies at the base of Husband Hill.

    By collecting photos like this at different times of day, when lighting comes from different directions, scientists can distinguish surface properties such as color and reflectivity from topography and roughness. By separating these components they can map more details of the geologic terrain, providing new clues about the geologic history of Gusev Crater.

  15. 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

  16. 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.

  17. 27 CFR 9.182 - Ribbon Ridge.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ..., 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. 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…

  3. 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…

  4. Feedback: Now with Physics

    NASA Astrophysics Data System (ADS)

    Hopkins, Philip F.; Quataert, Eliot; Faucher-Giguere, Claude-Andre; Keres, Dusan; Wetzel, Andrew R.; Murray, Norman W.

    2017-01-01

    The most fundamental unsolved problems in galaxy formation revolve around "feedback" from massive stars and black holes. In the last few years, a new generation of theoretical models have emerged which combine new numerical methods and physics in an attempt to realistically model the diverse physics of the interstellar medium, star formation, and feedback from super-massive black holes and massive stars (winds, jets, SNe, and radiation). These mechanisms lead to 'self-regulated' galaxy and star formation, in which global correlations such as the Schmidt-Kennicutt law, the inefficiency of star formation, and the stellar mass function -- emerge naturally. Within galaxies, feedback regulates the structure of the interstellar medium, and many observed properties of the ISM, star formation, and galaxies can be understood as a fundamental consequence of super-sonic turbulence in a rapidly cooling, self-gravitating medium. But feedback also produces galactic super-winds that can dramatically alter the cosmological evolution of galaxies, change the nature of dark matter cores and ‘cusps’, and re-structure the circum-galactic and inter-galactic medium. These winds depend non-linearly on multiple feedback mechanisms in a way that explains why they have been so difficult to model in previous "sub-grid" approaches. This resolves long-standing problems in understanding even apparently "simple" galaxy properties like the mass-metallicity relation. Finally, I'll discuss where feedback fails, and where either additional, exotic physics, or new, previously-dismissed feedback mechanisms, may be needed to explain observations.

  5. 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.

  6. Internal Tide Generation by Tall Ocean Ridges

    DTIC Science & Technology

    2009-09-01

    April 26th, 1996, of the area enclosed by the solid line in the map of the South China Sea (right). The dashed line indicates the location of the Luzon...115 15 4-9 Bathymetry of (a) the ridge at French Frigate Shoals (FFS) and (b) the Keana Ridge (KR) in the Kauai Channel. The...The thick lines in panel (b) indicate the raw bathymetry data (solid) and a smoothed version of the profile (dashed), and the inset presents the local

  7. Calibrated feedback for laser diodes

    SciTech Connect

    Howard, P.G.

    1986-04-22

    A method is described of calibrating the feedback output from the feedback light detector of the laser diode of an optical disk drive of a laser light pen which consists of mounting a first and a second resistor in a laser light pen; connecting the first resistor between the feedback light detector and ground; connecting the second resistor between the feedback light detector and a feedback output; operating the laser diode to produce a predetermined light power output; adjusting the resistance of the first resistor to produce a predetermined voltage at the feedback output; and adjusting the resistance of the second resistor to produce a predetermined impedance at the feedback output.

  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.

  9. Hydrothermal activity on the Gorda Ridge

    NASA Astrophysics Data System (ADS)

    Rona, Peter A.

    Near-bottom plumes of materials indicative of discharge of metal-rich hot springs were discovered at sites on the Gorda Ridge by a research team of government and university scientists on a cruise of the National Oceanic and Atmospheric Administration (NOAA) ship Surveyor during May 1985 as part of the NOAA Vents Program. The Gorda Ridge, off northern California and Oregon, is the only seafloor spreading center within the proclaimed 200-mile U.S. Exclusive Economic Zone (370 km wide) of the conterminous United States and is one of the last oceanic ridges to be explored for metal-rich hot springs. One reason for this neglect is that the Gorda Ridge is slow spreading, with half-rates ranging from 1.1 cm/yr in the southern portion to 2.2 cm/yr in the northern portion. Slow spreading centers have not been fully evaluated with regard to hydrothermal activity by many members of the research community, who have concentrated their attention on the faster spreading East Pacific Rise to the south and the Juan de Fuca Ridge to the north of the Gorda Ridge.

  10. 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.

  11. 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.

  12. 77 FR 68818 - Notice of Inventory Completion: U.S. Department of Energy Oak Ridge Office, Oak Ridge, TN

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-16

    ... National Park Service Notice of Inventory Completion: U.S. Department of Energy Oak Ridge Office, Oak Ridge... Oak Ridge Office has completed an inventory of human remains and associated funerary object, in... associated funerary object may contact the U.S. Department of Energy Oak Ridge Office. Repatriation of...

  13. 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

    ... National Park Service Notice of Inventory Completion: U.S. Department of Energy Oak Ridge Office, Oak Ridge.... 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...

  14. 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.

  15. 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

  16. 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

  17. Smart feedback loops

    NASA Astrophysics Data System (ADS)

    Chepurnov, A. S.; Gribov, I. V.; Gudkov, K. A.; Shumakov, A. V.; Shvedunov, V. I.

    1994-12-01

    It is necessary to find the golden mean in allocating the processing resources of a computer control system. Traditionally, feedback loops operate at the lower levels to ensure safe and stable operation of the accelerator. At present we use analogue and digital feedback loops. Some systems, such as the RF, require more complex algorithms. A possible way of providing these, using digital signal processors is described. The results of tests with the Race-Track Microtron Linac are given and the sources of the main internal and external disturbances have been analysed.

  18. 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.

  19. 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…

  20. 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…

  1. Signatures of AGN feedback

    NASA Astrophysics Data System (ADS)

    Wylezalek, Dominika; Zakamska, Nadia L.; MaNGA-GMOS Team

    2017-01-01

    Feedback from actively accreting SMBHs (Active Galactic Nuclei, AGN) is now widely considered to be the main driver in regulating the growth of massive galaxies. Observational proof for this scenario has, however, been hard to come by. Many attempts at finding a conclusive observational proof that AGN may be able to quench star formation and regulate the host galaxies' growth have shown that this problem is highly complex.I will present results from several projects that focus on understanding the power, reach and impact of feedback processes exerted by AGN. I will describe recent efforts in our group of relating feedback signatures to the specific star formation rate in their host galaxies, where our results are consistent with the AGN having a `negative' impact through feedback on the galaxies' star formation history (Wylezalek+2016a,b). Furthermore, I will show that powerful AGN-driven winds can be easily hidden and not be apparent in the integrated spectrum of the galaxy. This implies that large IFU surveys, such as the SDSS-IV MaNGA survey, might uncover many previously unknown AGN and outflows that are potentially very relevant for understanding the role of AGN in galaxy evolution (Wylezalek+2016c)!

  2. 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.

  3. 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…

  4. 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.

  5. Cell migration on ridges and cliffs

    NASA Astrophysics Data System (ADS)

    Driscoll, Meghan; McCann, Colin; Kopace, Rael; Watts, John; Homan, Tess; Losert, Wolfgang

    2009-03-01

    The amoeba Dictyostelium discoideum is a model system for the study of cellular migration, an important physiological process that occurs in embryonic development, wound healing, and cancer metastasis. We study the motion of D. discoideum on surfaces with various topographies, particularly those that affect the direction of cellular migration. Topographical features, such as ridges and cliffs, were fabricated using multiphoton absorption polymerization. As the cells encountered these topographical features, we tracked their overall motions and shapes, as well as the locations and intensities of certain intracellular signals. We found that when cells undergoing chemokinesis, random migration in response to a chemical signal, encounter a ridge, they tend to move along that ridge, even if the ridge is shorter than the cell. When cells undergoing chemotaxis, directed migration in response to a chemical signal, are directed off of a cliff, they do not fall off the cliff. Instead, they search for new attachment points, eventually change direction, and continue moving along the edge of the cliff. Both ridges and cliffs affect more than just the motion of a cell; they also affect its shape.

  6. 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

  7. Arctic Ocean: hydrothermal activity on Gakkel Ridge.

    PubMed

    Jean-Baptiste, Philippe; Fourré, Elise

    2004-03-04

    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.

  8. Cancer mortality near Oak Ridge, Tennessee.

    PubMed

    Mangano, J J

    1994-01-01

    Oak Ridge, Tennessee, is the site of one of the two oldest nuclear facilities in the United States. Although precise records have not been maintained, low levels of radioactive products have been released into the environment since the facility began operation in World War II. Changes in age-adjusted cancer mortality rates for whites between the periods 1950-1952 and 1987-1989 were analyzed to assess whether these radioactive releases have had any adverse effects on the population living near Oak Ridge. Results indicate that the increases in the local area (under 100 miles from Oak Ridge) exceeded regional increases and far exceeded national increases. Within the region, increases were greatest in rural areas, in Anderson County (where Oak Ridge is located), in mountainous counties, and in the region downwind of Oak Ridge. Each of these findings suggest that low levels of radiation, ingested gradually by local residents, were a factor in the increases in local cancer death rates. Results indicate that more studies of this type are called for and that cessation of all future radioactive emissions from nuclear facilities should be considered.

  9. 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.

  10. Global Characterization of the Ocean Ridge System

    NASA Astrophysics Data System (ADS)

    Gale, A.; Langmuir, C. H.; Dalton, C. A.

    2010-12-01

    The mid-ocean ridge system is a window into the upper mantle, producing over 80% of Earth’s volcanism. Fundamental, first-order questions remain debated and require a reliable global perspective. Such questions include the relative roles of mantle temperature, mantle heterogeneity and spreading rate on mid-ocean ridge basalt (MORB) compositions, and the importance of spreading rate to melting and fractionation processes. To address these issues and provide a common reference for geochemists and geophysicists, we have assembled a comprehensive petrological presentation of global MORB. The data are compiled from PetDB as well as unpublished data. Transforming the raw data into a useful catalog poses several challenges. First, to link each sample with a particular ridge segment requires defining the individual segments of the ridge system. Using the highest resolution bathymetry available, we identified 771 global ridge segments with a total length of 60,864km. For each segment we also generated a digital along-strike depth profile, enabling precise characterization of both mean depth and depth range. Second, as noted in earlier work, different laboratories calibrate their analyses to different standards, which can lead to significant, systematic offsets among analyses. It is therefore important to apply correction factors to the data to make them consistent with one another. Erroneous data and mislocated samples were identified and either eliminated or manually corrected, leading to a total dataset of 11,366 glass and 874 whole-rock analyses that have had interlab correction values carefully applied. These results show that the mean depth of the global ridge system is 2981m, calculated by averaging the segment mean depths, weighted by segment length. Of the 771 ridge segments, 476 have at least one basalt sample within 10km of the ridge axis but only 181 segments have samples from three or more unique locations. Using these data, a far more reliable composition can

  11. Delayed CO2 emissions from mid-ocean ridge volcanism as a possible cause of late-Pleistocene glacial cycles

    NASA Astrophysics Data System (ADS)

    Huybers, Peter; Langmuir, Charles H.

    2017-01-01

    The coupled 100,000 year variations in ice volume, temperature, and atmospheric CO2 during the late Pleistocene are generally considered to arise from a combination of orbital forcing, ice dynamics, and ocean circulation. Also previously argued is that changes in glaciation influence atmospheric CO2 concentrations through modifying subaerial volcanic eruptions and CO2 emissions. Building on recent evidence that ocean ridge volcanism responds to changes in sea level, here it is suggested that ocean ridges may play an important role in generating late-Pleistocene 100 ky glacial cycles. If all volcanic CO2 emissions responded immediately to changes in pressure, subaerial and ocean-ridge volcanic emissions anomalies would oppose one another. At ocean ridges, however, the egress of CO2 from the mantle is likely to be delayed by tens-of-thousands of years, or longer, owing to ascent time. A simple model involving temperature, ice, and CO2 is presented that oscillates at ∼100 ky time scales when incorporating a delayed CO2 contribution from ocean ridge volcanism, even if the feedback accounts for only a small fraction of total changes in CO2. Oscillations readily become phase-locked with insolation forcing associated with changes in Earth's orbit. Under certain parameterizations, a transition from ∼40 ky to larger ∼100 ky oscillations occurs during the middle Pleistocene in response to modulations in orbital forcing. This novel description of Pleistocene glaciation should be testable through ongoing advances in understanding the circulation of carbon through the solid earth.

  12. ORLANDO -- Oak Ridge Large Neutrino Detector

    SciTech Connect

    Bugg, W.; Cohn, H.; Efremenko, Yu.; Gabriel, T.; Kamyshkov, Yu.; Plasil, F.; Fazely, A.; Svoboda, R.

    1997-12-01

    The authors discuss a proposal for construction of an Oak Ridge LArge Neutrino DetectOr (ORLANDO) to search for neutrino oscillations at the Spallation Neutron Source (SNS). A 4 MW SNS is proposed to be built at the Oak Ridge National Laboratory with the first stage to be operative around 2006. It will have two target stations, which makes it possible with a single detector to perform a neutrino oscillation search at two different distances. Initial plans for the placement of the detector and the discovery potential of such a detector are discussed.

  13. 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.

  14. 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.

  15. 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…

  16. 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.…

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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…

  2. 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.

  3. 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.

  4. 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.

  5. 25 MV tandem accelerator at Oak Ridge

    SciTech Connect

    Jones, C.M.

    1980-01-01

    A new heavy-ion accelerator facility is under construction at the Oak Ridge National Laboratory. A brief description of the scope and status of this project is presented with emphasis on the first operational experience with the 25 MV tandem accelerator.

  6. Ridge Regression: A Regression Procedure for Analyzing correlated Independent Variables

    ERIC Educational Resources Information Center

    Rakow, Ernest A.

    1978-01-01

    Ridge regression is a technique used to ameliorate the problem of highly correlated independent variables in multiple regression analysis. This paper explains the fundamentals of ridge regression and illustrates its use. (JKS)

  7. 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.

  8. 15. Yankee Horse Ridge. View of the trail crossing the ...

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

    15. Yankee Horse Ridge. View of the trail crossing the Yankee Horse Railroad bed. Facing south. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  9. 16. Yankee Horse Ridge. View of the Yankee Horse Railroad ...

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

    16. Yankee Horse Ridge. View of the Yankee Horse Railroad trestle looking north. Looking north. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  10. 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.

  11. Seismic hazard evaluation for Department of Energy Oak Ridge Reservations, Oak Ridge, Tennessee

    SciTech Connect

    McGuire, R.K.; Toro, G.F.; Hunt, R.J.

    1992-09-30

    This study presents the results of an investigation of seismic hazard at the Department of Energy Oak Ridge Reservations (K-25 Site, Oak Ridge National Laboratories, and Oak Ridge Y-12 Plant), located in Oak Ridge, Tennessee. Oak Ridge is located in eastern Tennessee, in an area of moderate to high historical seismicity. Results from two separate seismic hazard analyses are presented. The EPRI/SOG analysis uses the input data and methodology developed by the Electric Power Research Institute, under the sponsorship of several electric utilities, for the evaluation of seismic hazard in the central and eastern United States. The LLNL analysis uses the input data and methodology developed by the Lawrence Livermore National Laboratory for the Nuclear Regulatory Commission. Both the EPRI/SOG and LLNL studies characterize earth-science uncertainty on the causes and characteristics of earthquakes in the central and eastern United States. This is accomplished by considering multiple hypotheses on the locations and parameters of seismic source zones and by considering multiple attenuation functions for the prediction of ground shaking given earthquake size and location. These hypotheses were generated by multiple expert teams and experts. Furthermore, each team and expert was asked to generate multiple hypotheses in order to characterize his own internal uncertainty. The seismic-hazard calculations are performed for all hypotheses. Combining the results from each hypothesis with the weight associated to that hypothesis, one obtains an overall representation of the seismic hazard at the Oak Ridge site and its uncertainty.

  12. Analyzing Feedback Control Systems

    NASA Technical Reports Server (NTRS)

    Bauer, Frank H.; Downing, John P.

    1987-01-01

    Interactive controls analysis (INCA) program developed to provide user-friendly environment for design and analysis of linear control systems, primarily feedback control. Designed for use with both small- and large-order systems. Using interactive-graphics capability, INCA user quickly plots root locus, frequency response, or time response of either continuous-time system or sampled-data system. Configuration and parameters easily changed, allowing user to design compensation networks and perform sensitivity analyses in very convenient manner. Written in Pascal and FORTRAN.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. Haptic gas pedal feedback.

    PubMed

    Mulder, M; Mulder, M; van Paassen, M M; Abbink, D A

    2008-11-01

    Active driver support systems either automate a control task or present warnings to drivers when their safety is seriously degraded. In a novel approach, utilising neither automation nor discrete warnings, a haptic gas pedal (accelerator) interface was developed that continuously presents car-following support information, keeping the driver in the loop. This interface was tested in a fixed-base driving simulator. Twenty-one drivers between the ages of 24 and 30 years participated in a driving experiment to investigate the effects of haptic gas pedal feedback on car-following behaviour. Results of the experiment indicate that when haptic feedback was presented to the drivers, some improvement in car-following performance was achieved, while control activity decreased. Further research is needed to investigate the effectiveness of the system in more varied driving conditions. Haptics is an under-used modality in the application of human support interfaces, which usually draw on vision or hearing. This study demonstrates how haptics can be used to create an effective driver support interface.

  19. Feedback in clinical medical education.

    PubMed

    Ende, J

    1983-08-12

    In the setting of clinical medical education, feedback refers to information describing students' or house officers' performance in a given activity that is intended to guide their future performance in that same or in a related activity. It is a key step in the acquisition of clinical skills, yet feedback is often omitted or handled improperly in clinical training. This can result in important untoward consequences, some of which may extend beyond the training period. Once the nature of the feedback process is appreciated, however, especially the distinction between feedback and evaluation and the importance of focusing on the trainees' observable behaviors rather than on the trainees themselves, the educational benefit of feedback can be realized. This article presents guidelines for offering feedback that have been set forth in the literature of business administration, psychology, and education, adapted here for use by teachers and students of clinical medicine.

  20. Ridge systems of Mars. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Gifford, A. W.

    1981-01-01

    Mare-type ridges on the Planet Mars were mapped and described based on Viking images. The ridges mapped range from 5 to 400 km long and 1 to 8 km wide. Most ridges on Mars are on plains and plateau units; 4,321 ridges with a total length of 153,835 km were mapped on these unit types. Ridges which resemble lunar mare ridges were also mapped in craters, basins, and several volcanic calderas on Mars. Mapping of ridges on a global scale reveals that they are preferentially developed in older, thinner plains units probably of flood basalt origin. Measuring the trends of ridges in plains units on Mars shows that there is a planetwide predominance of north, northwest and northeast trends. It is proposed that ridges are compressional tectonic features which have formed in response to changes in the planet's rotational equilibrium figure early in its history. In addition, the Tharsis uplift has created a regional stress system which accounts for the trends of ridges in areas near by. Ridges in craters and basins are similarly caused by shortening across the basin in response to regional stresses.

  1. 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.

  2. Does the lateral intercondylar ridge disappear in ACL deficient patients?

    PubMed

    van Eck, Carola F; Morse, Kenneth R; Lesniak, Bryson P; Kropf, Eric J; Tranovich, Michael J; van Dijk, C Niek; Fu, Freddie H

    2010-09-01

    The aim of this study was to determine whether there is a difference in the presence of the lateral intercondylar ridge and the lateral bifurcate ridge between patients with sub-acute and chronic ACL injuries. We hypothesized that the ridges would be present less often with chronic ACL deficiency. Twenty-five patients with a chronic ACL injury were matched for age and gender to 25 patients with a sub-acute ACL injury. The lateral intercondylar ridge and lateral bifurcate ridge were scored as either present, absent, or indeterminate due to insufficient visualization by three blinded observers. The kappa for the three observers was .61 for the lateral intercondylar ridge and .58 for the lateral bifurcate ridge. The lateral intercondylar ridge was present in 88% of the sub-acute patients and 88% of the chronic patients. The lateral bifurcate ridge was present in 48% of the sub-acute and 48% of the chronic patients. This matched-pairs case-control study was unable to show a difference in the presence of the femoral bony ridges between patients with acute and chronic ACL injuries. The authors would suggest looking for the ridges as a landmark of the native ACL insertion site during ACL reconstruction in both acute and chronic ACL injuries.

  3. 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.

  4. Active convection beneath ridges: a new spin

    NASA Astrophysics Data System (ADS)

    Katz, R. F.

    2009-12-01

    The role of buoyancy-driven, "active" upwelling beneath mid-ocean ridges has been long debated [1,2,3], with the naysayers holding sway in recent years. Recent work on tomographic imaging of the sub-ridge mantle has revealed patterns in velocity variation that seem inconsistent with what we expect of passive upwelling and melting [4]. The irregular distribution, asymmetry, and off-axis locations of slow regions in tomographic results are suggestive of time-dependent convective flow. Using 2D numerical simulations of internally consistent mantle and magmatic flow plus melting/freezing [5,6], I investigate the parametric subspace in which active convection is expected to occur. For low mantle viscosities, interesting symmetry-breaking behavior is predicted. References: [1] Rabinowicz, et al., EPSL, 1984; [2] Buck & Su, GRL, 1989; [3] Scott & Stevenson, JGR, 1989; [4] Toomey et al., Nature, 2007; [5] McKenzie, J.Pet., 1984; [6] Katz, J.Pet., 2008;

  5. An Investigation of Dielectric Loaded Ridged Waveguide.

    DTIC Science & Technology

    1986-03-31

    propagation in any waveguide may be characterized by its field distribution. For homogeneous waveguides, modes are usually classified as TE (transverse...modes other than TE,,,.0 are characterized as LSE or LSM. Introduction of the ridge will cause distortion of the fields from true LSE or LSM nature...specify each of the LSE and LSM modes with any given mode characterized as the LSEm, mode or the LSM ,, mode. The first index m refers to the

  6. 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.

  7. Leadership Computing at Oak Ridge National Laboratory

    SciTech Connect

    Kuehn, Jeffery A; Studham, Scott; White III, James B; Fahey, Mark R; Carter, Steven M; Nichols, Jeffrey A

    2005-05-01

    Oak Ridge National Laboratory is running the world's largest Cray X1, the world's largest unclassified Cray XT3, and a Cray XD1. In this report we provide an overview of the applications requiring leadership computing and the performance characteristics of the various platforms at ORNL. We then discuss ways in which we are working with Cray to establish a roadmap that will provide 100's of teraflops of sustained performance while integrating a balance of vector and scalar processors.

  8. Segmentation of mid-ocean ridges

    USGS Publications Warehouse

    Schouten, Hans; Klitgord, Kim D.; Whitehead, J.A.

    1985-01-01

    Studies of mid-ocean ridges in the Pacific and Atlantic oceans show that the volcanism that forms the oceanic crust along the spreading-plate boundaries is concentrated at regular intervals related to spreading rate. This observation and a new calculation for a Rayleigh-Taylor type of gravitational instability of a partially molten mantle region growing under spreading centres yield reasonable estimates of upper mantle viscosities. ?? 1985 Nature Publishing Group.

  9. Oak Ridge 25-MV tandem accelerator

    SciTech Connect

    Ziegler, N.F.; Richardson, E.G.; Mann, J.E.; Juras, R.C.; Jones, C.M.; Biggerstaff, J.A.; Benjamin, J.A.

    1981-01-01

    A new heavy-ion accelerator facility is nearing completion at the Oak Ridge National Laboratory. This paper presents a brief description of the scope and status of this project and a discussion of some aspects of the first operational experience with the 25 MV tandem accelerator which is being provided by the National Electrostatics Corporation (NEC) as a major component of the first phase of the facility.

  10. 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.

  11. Modeling climate related feedback processes

    SciTech Connect

    Elzen, M.G.J. den; Rotmans, J. )

    1993-11-01

    In order to assess their impact, the feedbacks which at present can be quantified reasonably are built into the Integrated Model to Assess the Greenhouse Effect (IMAGE). Unlike previous studies, this study describes the scenario- and time-dependent role of biogeochemical feedbacks. A number of simulation experiments are performed with IMAGE to project climate changes. Besides estimates of their absolute importance, the relative importance of individual biogeochemical feedbacks is considered by calculating the gain for each feedback process. This study focuses on feedback processes in the carbon cycle and the methane (semi-) cycle. Modeled feedbacks are then used to balance the past and present carbon budget. This results in substantially lower projections for atmospheric carbon dioxide than the Intergovernmental Panel on Climate Change (IPCC) estimates. The difference is approximately 18% from the 1990 level for the IPCC [open quotes]Business-as-Usual[close quotes] scenario. Furthermore, the IPCC's [open quotes]best guess[close quotes] value of the CO[sub 2] concentration in the year 2100 falls outside the uncertainty range estimated with our balanced modeling approach. For the IPCC [open quotes]Business-as-Usual[close quotes] scenario, the calculated total gain of the feedbacks within the carbon cycle appears to be negative, a result of the dominant role of the fertilization feedback. This study also shows that if temperature feedbacks on methane emissions from wetlands, rice paddies, and hydrates do materialize, methane concentrations might be increased by 30% by 2100. 70 refs., 17 figs., 7 tabs.

  12. 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.

  13. 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.

  14. 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

  15. The Northern Kolbeinsey Ridge, North Atlantic: Excess volcanism and ridge relocations close to Jan Mayen

    NASA Astrophysics Data System (ADS)

    Yeo, I. A.; Augustin, N.; Devey, C. W.; Deutschmann, M.; Elkins, L. J.; Laurila, T.; Meisenhelder, K.; Rivers, E.; Rothenbeck, M.; van der Zwan, F. M.

    2012-12-01

    The slow-spreading (1.8 cm/yr full rate) Northern Kolbeinsey Ridge (NKR) segment of the Mid-Atlantic Ridge, which lies immediately south of the major Jan Mayen Transform Fault, is characterised by anomalously thick crust and unusually shallow water depths. A lack of precise surveying meant that the tectonics and volcanology of the ridge were previously unknown. We present the preliminary findings from 20 days of sampling and mapping of the NKR between 70°30 N and 71°45 N in July 2012. Over 3,130 km2 of the ridge axis were imaged with ship-based multibeam at 35 m or better resolution, while a further 290 km2 were imaged with high-resolution (~ 1 m) sidescan sonar and multibeam surveys using the AUV "ABYSS". This unique dataset, alongside dredge and volcanic rock corer sampling, allows us to define the location of current volcanic crustal accretion for the first time and reveals a complex pattern of volcanism and tectonics along the ridge. At its northern, deeper end we image a single, 025° trending, 4 -5 km wide axial valley, divided into zones dominated alternately by flatter seafloor and closely spaced flat-topped seamounts. As the seafloor shallows southward, the number of flat-topped seamounts decreases and the axial volcanism becomes dominated by sheet- and hummocky flows. At its shallowest point, the axis is flanked on its eastern side by a large, 5 km diameter central volcano (forming Eggvin Bank, min. water depth 20m). The volcano displays a summit caldera containing fresh basalts (the freshest sampled on the entire ridge) as well as relatively fresh flows on its southern flank. South of Eggvin volcano the ridge is cut by an oblique (68° trending), normal fault bounded valley, which extends 7 km southwest from the current active ridge to the north. This oblique valley connects with two further 025° trending parallel valleys to the south: one in line with the axis to the north and a second 7 km to the west. Both valleys appear to have been recently

  16. A laser feedback interferometer with an oscillating feedback mirror

    NASA Astrophysics Data System (ADS)

    Wang, Zhi-Guo; Wang, Fei; Xiao, Guang-Zong

    2012-11-01

    A method is proposed to solve the problem of direction discrimination for laser feedback interferometers. By vibrating the feedback mirror with a small-amplitude and high-frequency sine wave, laser intensity is modulated accordingly. The modulation amplitude can be extracted using a phase sensitive detector (PSD). When the feedback mirror moves, the PSD output shows a quasi-sine waveform similar to a laser intensity interference fringe but with a phase difference of approximately ±π/2. If the movement direction of the feedback mirror changes, the phase difference sign reverses. Therefore, the laser feedback interferometer offers a potential application in displacement measurement with a resolution of 1/8 wavelength and in-time direction discrimination. Without using optical components such as polarization beam splitters and wave plates, the interferometer is very simple, easy to align, and less costly.

  17. 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.

  18. 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…

  19. Feedback Seeking in Training Settings.

    ERIC Educational Resources Information Center

    Kuchinke, K. Peter

    The role of feedback in training settings was examined in a survey-based study of feedback in nine 5-day management development training courses in a United Kingdom government agency. The courses followed a highly standardized curriculum and delivery process. Although the courses were primarily instructor-and theory-centered, they also included…

  20. Interpersonal Feedback: Origins and Applications.

    ERIC Educational Resources Information Center

    Barbour, Alton

    This paper identifies the origins of the concept of feedback and its entry into the interpersonal communication literature as a social science variable. It touches on why feedback might be important in interpersonal relations, what it consists of, some of the relevant research, and some possible dangers or misuses. It speaks to how the process of…

  1. Haptic feedback helps bipedal coordination.

    PubMed

    Roelofsen, Eefje G J; Bosga, Jurjen; Rosenbaum, David A; Nijhuis-van der Sanden, Maria W G; Hullegie, Wim; van Cingel, Robert; Meulenbroek, Ruud G J

    2016-10-01

    The present study investigated whether special haptic or visual feedback would facilitate the coordination of in-phase, cyclical feet movements of different amplitudes. Seventeen healthy participants sat with their feet on sliding panels that were moved externally over the same or different amplitudes. The participants were asked to generate simultaneous knee flexion-extension movements, or to let their feet be dragged, resulting in reference foot displacements of 150 mm and experimental foot displacements of 150, 120, or 90 mm. Four types of feedback were given: (1) special haptic feedback, involving actively following the motions of the sliders manipulated by two confederates, (2) haptic feedback resulting from passive motion, (3) veridical visual feedback, and (4) enhanced visual feedback. Both with respect to amplitude assimilation effects, correlations and standard deviation of relative phase, the results showed that enhanced visual feedback did not facilitate bipedal independence, but haptic feedback with active movement did. Implications of the findings for movement rehabilitation contexts are discussed.

  2. 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…

  3. Motivating Students through Formative Feedback

    ERIC Educational Resources Information Center

    Mauch, Lois

    2007-01-01

    Technology tools that are used to help apply standards and benchmarks motivate physical educators to use new methods of teaching, and create new ways to provide students with direct formative feedback, the number one motivator for students. Direct formative feedback refers to verbal communication between the teacher and/or parent and student. The…

  4. Feedback Control for Aerodynamics (Preprint)

    DTIC Science & Technology

    2006-09-01

    AFRL-VA-WP-TP-2006-348 FEEDBACK CONTROL FOR AERODYNAMICS (PREPRINT) R. Chris Camphouse, Seddik M. Djouadi, and James H. Myatt...CONSTRUCTION FOR THE DESIGN OF BOUNDARY FEEDBACK CONTROLS FROM REDUCED ORDER MODELS (PREPRINT) 5c. PROGRAM ELEMENT NUMBER 0601102F 5d. PROJECT NUMBER...

  5. 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…

  6. The Sound of Feedback in Higher Education

    ERIC Educational Resources Information Center

    Savin-Baden, Maggi

    2010-01-01

    Whilst there is considerable literature on feedback for students and on the use of audio feedback, literature in the area of podcasting assignment feedback (PAF) remains sparse. Partly, this may be due to a lack of clarity about what counts as feedback, the way in which feedback is located pedagogically and the relationship between feedback…

  7. 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…

  8. 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…

  9. The Cocos and Carnegie Ridges: A Record of Long-term Galapagos Plume-Ridge Interaction

    NASA Astrophysics Data System (ADS)

    Harpp, K. S.; Wanless, V.; Hoernle, K.

    2001-12-01

    The present-day Galapagos Archipelago exhibits an astonishingly wide variety of geochemical compositions, from enriched, hotspot-like signatures in the west and south to MORB-like lavas in the central and northern regions. The distinctive spatial zonation has been attributed to a heterogeneous plume and its extensive interaction with the asthenosphere. One of the controversial questions about the Galapagos system is whether the geochemical zonation in the present-day archipelago is a long-term phenomenon due to inherent plume heterogeneity or only the recent result of short-lived mantle contamination. The aseismic Cocos and Carnegie Ridges record the last 20 Ma of plume activity as the Cocos and Nazca plates, respectively, have moved over the hotspot. During the 1999 PAGANINI expedition, we collected over 80 dredge samples from the ridges to explore the temporal variations of the Galapagos plume. Preliminary results suggested that lavas dredged off the west coast of Central America preserve the geochemical zonation observed in the Galapagos Archipelago today. Trace element determinations from dredge sites along the Cocos and Carnegie Ridges indicate, however, that the situation is (not surprisingly) more complex. Instead, the geochemical variations observed along the ridges may be controlled predominantly by the relative positions of the Galapagos plume and the Galapagos Spreading Center (GSC). The GSC has been migrating to the NE relative to the hotspot. For the oldest portions of the Cocos Ridge, the plume was located beneath the Nazca plate and did not interact with the GSC. Lavas produced during this time therefore represent pristine plume, with compositions more enriched than those of the present-day Galapagos; these are observed NE of Cocos Island. As the ridge migrates closer to the hotspot, plume-mid-ocean ridge interaction intensifies, resulting in the dilution of hotspot lavas by entrained, depleted asthenosphere. Consistently, younger lavas along the

  10. 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.

  11. Feedback on the Feedback: Sociocultural Interpretation of Saudi ESL Learners' Opinions about Writing Feedback

    ERIC Educational Resources Information Center

    Mustafa, Rami F.

    2012-01-01

    This qualitative study employed informal conversational interviews and semi-structured individual interviews to capture the Saudi students' opinions about the feedback they receive, and about their perceptions on what constitutes helpful feedback. Sociocultural theory was used as the framework of this study. The findings suggest that the Saudi…

  12. 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…

  13. 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.

  14. An abrupt change in ridge axis gravity with spreading rate

    NASA Technical Reports Server (NTRS)

    Small, Christopher; Sandwell, David T.

    1989-01-01

    A total of 44 Geosat profiles over ridges with spreading rates ranging from 14 to 155 mm/yr were analyzed. In agreement with previous studies, it is found that slow spreading ridges usually have high amplitude gravity troughs, while fast spreading ridges are characterized by low-amplitude ridge axis highs. Unexpectedly, it is found that the transition from axial trough to axial high occurs abruptly at a spreading rate of 60-70 mm/yr. Ridge axis gravity signatures are highly variable for rates less than 65 mm/yr and very uniform at higher rates. The transition of the gravity signature appears to get more abrupt than the transition of the topographic signature, suggesting an abrupt change in the style of isostatic compensation with spreading rate. Published models of ridge axis dynamics do not explain this sharp transition.

  15. Ridge network detection in crumpled paper via graph density maximization.

    PubMed

    Hsu, Chiou-Ting; Huang, Marvin

    2012-10-01

    Crumpled sheets of paper tend to exhibit a specific and complex structure, which is described by physicists as ridge networks. Existing literature shows that the automation of ridge network detection in crumpled paper is very challenging because of its complex structure and measuring distortion. In this paper, we propose to model the ridge network as a weighted graph and formulate the ridge network detection as an optimization problem in terms of the graph density. First, we detect a set of graph nodes and then determine the edge weight between each pair of nodes to construct a complete graph. Next, we define a graph density criterion and formulate the detection problem to determine a subgraph with maximal graph density. Further, we also propose to refine the graph density by including a pairwise connectivity into the criterion to improve the connectivity of the detected ridge network. Our experimental results show that, with the density criterion, our proposed method effectively automates the ridge network detection.

  16. 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.

  17. Neutron Instruments Added at Oak Ridge

    SciTech Connect

    Ekkebus, Allen E

    2011-01-01

    The neutron scattering facilities at Oak Ridge National Laboratory continue their development as new instruments are commissioned and join the user program at the Spallation Neutron Source and High Flux Isotope Reactor. More than 640 proposals were received for beam time during the January-May 2011 period on SNS and HFIR instruments with about half either being accepted or identified as alternates. The proposal call for the period June-December 2011, announced at http://neutrons.ornl.gov, will close February 23, 2011.

  18. 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.

  19. 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

  20. Children's reasoning about evaluative feedback.

    PubMed

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

    2009-11-01

    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 negative feedback, and this tendency was strongest among the younger children. In Study 2, the expectation that peers would preferentially disclose positive feedback was replicated among children from the USA, and was also seen among younger but not older children from China. Participants in all groups took the relationship between communication partners into account when predicting whether peers would express evaluative feedback. Results of open-ended responses suggested cross-cultural differences, including a greater emphasis by Chinese children on the implications of evaluative feedback for future performance, and reference by some older Chinese children to the possibility that positive feedback might make the recipient 'too proud'.

  1. 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.

  2. Historical Gorda Ridge t-phase swarms: relationships to ridge structure and the tectonic and volcanic state of the ridge during 1964 1966

    NASA Astrophysics Data System (ADS)

    Walker, Daniel A.; Hammond, Stephen R.

    1998-12-01

    The U.S. Navy's Sound Surveillance System (SOSUS) hydrophone arrays are extemely efficient receptors of a high-frequency earthquake energy phase known as the t(ertiary)-wave, or t-phase (Fox et al., 1994). After a nearly 30-year hiatus in such studies, SOSUS arrays are again being utilized to detect t-phases and to locate seismic and volcanic events occurring along the Gorda seafloor spreading center (Fox et al., 1995; Fox and Dziak, 1998). Earlier, Northrop et al. (1968) also used other military arrays to infer tectonic structure along the Gorda Ridge. From October 1964 through December 1966, over 600 low-magnitude earthquakes occurred along the Gorda Ridge. Nearly all of these events had magnitudes below the detection thresholds of land-based seismic networks. Northrop et al. (1968) interpreted the geographic distribution of these events as evidence for a nascent fracture zone near the midpoint of the ridge. In the present study, the spatial distributions of these older data and, for the first time, their temporal distributions as well, were examined with respect to detailed bathymetry of the ridge that was acquired in the early 1980s. This analysis, of 570 on-axis and 74 off-axis events, led to the following observations: (1) nearly all of the Gorda Ridge t-phase events occurred in discreet swarms centered about the ridge axis, (2) most of the events within each of 8 (of 9) observed swarms occurred mainly along single ridge segments, and, (3) reconfirming the earlier Northrop et al. (1968) conclusion, most of the events originated in the region of a major change in the strike of the ridge axis. During the 27-month interval that the ridge was observed, relatively few t-phase events took place along the northernmost segment of the Gorda Ridge where the 1996 eruption occurred. However, a unique sequence of small events which visually resemble the events associated with a Juan de Fuca Ridge eruption in 1993 (Fox et al., 1995) and a Gorda Ridge eruption in 1996 (Fox

  3. New beach ridge type: severely limited fetch, very shallow water

    SciTech Connect

    Tanner, W.F.; Demirpolat, S.

    1988-09-01

    The southern end of Laguna Madre (Texas) north of the Rio Grande mouth is marked by very shallow water, wide tidal flats, lunettes, islands made of beach ridges, and lesser features. The number and variety of islands in the lagoon is remarkable. The lunettes (clay dunes) are made primarily of quartz sand and coarse silt. They are common 5-10 m high, irregular in shape, and steep sided. They were deposited from wind transport and did not migrate. Those that are islands in the lagoon predate present position of sea level. Islands made of beach ridges were built from the lagoon side. Photoanalysis, field work, and granulometry all show that this sand was not moved into these ridges by Gulf of Mexico waves. Trenches in 12 beach ridges showed horizontal bedding but neither low-angle nor steep cross-bedding (quite unlike swash-built beach ridges). The ridges were built by wind-tide lag effects, not from the swash. Therefore, these beach ridges are a new type, in addition to swash-built, eolian, and storm-surge ridges. Growth of the ridges appears to be completed.

  4. 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.

  5. 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.

  6. 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

  7. Multiple expressions of plume-ridge interaction at the Galapagos: Volcanic lineaments and ridge jumps

    NASA Astrophysics Data System (ADS)

    Mittelstaedt, E. L.; Soule, S. A.; Harpp, K. S.; Fornari, D. J.

    2011-12-01

    Despite significant evidence for communication between an upwelling mantle plume beneath the Galápagos Archipelago (GA) and the nearby Galápagos Spreading Center (GSC), little is known about the dynamics of the interaction between the ridge and the hotspot. We use new bathymetry, sidescan sonar, magnetic, subbottom seismic, and gravity data from the FLAMINGO cruise (MV1007) to address the mechanism of plume-ridge interaction in the Northern Galápagos Volcanic Province (NGVP), a region centered on the 90° 50'W Galápagos transform fault (GTF). West of the GTF, the Nazca Plate is dominated by numerous seamounts aligned in 3 volcanic lineaments. Volumetrically, the lineaments are composed of ~1500 km3 of erupted lavas. Faulting patterns and seamount elongations suggest that the locations and orientations of the lineaments may be partly controlled by the lithospheric stress field. In contrast, east of the GTF on the Cocos Plate, there is little evidence of constructional volcanism (~69 km3). However, we observe several linear, nearly ridge-parallel, faulted features separating sediment-filled basins, and two large bathymetric highs with up to 1km of relief. Differences in seafloor west and east of the GTF are also observed in the Residual Mantle Bouguer Anomaly (RMBA). On the Nazca Plate, RMBA lows closely contour the volcanic lineaments with minima at the centers of the largest volcanoes along the Wolf-Darwin Lineament. On the Cocos Plate, the RMBA at a given distance from the ridge axis is generally more negative than at similar locations on the Nazca Plate. In addition, two RMBA lows are observed coincident with the observed bathymetric highs, both of which are slightly elongate in a direction sub-parallel to the Eastern GSC, possibly reflecting a period of increased magma flux along a former ridge axis. Magnetic anomalies reveal a complicated history of plate evolution including a series of ridge jumps since ~3 Ma that result in creation of the GTF. We invert

  8. Robust Control Feedback and Learning

    DTIC Science & Technology

    2002-11-30

    98-1-0026 5b. GRANT NUMBER Robust Control, Feedback and Learning F49620-98-1-0026 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Michael G...Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 Final Report: ROBUST CONTROL FEEDBACK AND LEARNING AFOSR Grant F49620-98-1-0026 October 1...Philadelphia, PA, 2000. [16] M. G. Safonov. Recent advances in robust control, feedback and learning . In S. 0. R. Moheimani, editor, Perspectives in Robust

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. [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.

  15. 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.

  16. 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.

  17. Ghrelin and feedback systems.

    PubMed

    Nonogaki, Katsunori

    2008-01-01

    Ghrelin is produced primarily in the stomach in response to hunger, and circulates in the blood. Plasma ghrelin levels increase during fasting and decrease after ingesting glucose and lipid, but not protein. The efferent vagus nerve contributes to the fasting-induced increase in ghrelin secretion. Ghrelin secreted by the stomach stimulates the afferent vagus nerve and promotes food intake. Ghrelin also stimulates pituitary gland secretion of growth hormone (GH) via the afferent vagus nerve. GH inhibits stomach ghrelin secretion. These findings indicate that the vagal circuit between the central nervous system and stomach has a crucial role in regulating plasma ghrelin levels. Moreover, body mass index modulates plasma ghrelin levels. In a lean state and anorexia nervosa, plasma ghrelin levels are increased, whereas in obesity, except in Prader-Willi syndrome, plasma ghrelin levels are decreased and the feeding- and sleeping-induced decline in plasma ghrelin levels is disrupted. There are two forms of ghrelin: active n-octanoyl-modified ghrelin and des-acyl ghrelin. Fasting increases both ghrelin types compared with the fed state. Hyperphagia and obesity are likely to decrease plasma des-acyl ghrelin, but not n-octanoyl-modified ghrelin levels. Hypothalamic serum and glucocorticoid-inducible kinase-1 and serotonin 5-HT2C/1B receptor gene expression levels are likely to be proportional to plasma des-acyl ghrelin levels during fasting, whereas they are likely to be inversely proportional to plasma des-acyl ghrelin levels in an increased energy storage state such as obesity. Thus, a dysfunction of the ghrelin feedback systems might contribute to the pathophysiology of obesity and eating disorders.

  18. 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

  19. Feedback Control of Rotor Overspeed

    NASA Technical Reports Server (NTRS)

    Churchill, G. B.

    1984-01-01

    Feedback system for automatically governing helicopter rotor speed promises to lessen pilot's workload, enhance maneuverability, and protect airframe. With suitable modifications, concept applied to control speed of electrical generators, automotive engines and other machinery.

  20. Martian wrinkle ridge topography: Evidence for subsurface faults from MOLA

    NASA Astrophysics Data System (ADS)

    Golombek, M. P.; Anderson, F. S.; Zuber, M. T.

    2001-10-01

    Mars Orbiter Laser Altimeter (MOLA) topography shows distinct elevation offsets across wrinkle ridges that can be explained simply by subsurface thrust faults. MOLA has provided the first reliable topographic data of wrinkle ridges to test models for their origin; although previous work has shown that wrinkle ridges result from compressional folding and faulting of near-surface units, the role of thrust faulting and its depth penetration have been argued. Topographic profiles across wrinkle ridges in Solis Planum, Lunae Planum, Tempe Terra, Xanthe Terra, Arcadia, Terra Sirenum, Thaumasia Planum, Arabia Terra, Syrtis Major, and Hesperia Planum show characteristic features such as superposed hills, crenulations, and elevation offsets between the plains on either side of the ridge. The characteristic elevation offsets between plains surfaces on either side of the ridges shown by MOLA are easily explained by subsurface thrust faults that underlie the ridges and produce the offset. In Solis Dorsa, wrinkle ridges are 10-20 km wide (well resolved by the 300 m spaced MOLA elevations), have a total relief of 80-250 m, and have elevation offsets of 50-180 m (well above the uncertainty in the MOLA elevations). MOLA topography shows that the plains decrease in elevation toward the southeast and are deformed into folds or arches not visible in images that are parallel to and in between the ridges. The elevations of the plains on either side of the ridges in Solis and Lunae Plana are characteristically down to the southeast and east, respectively, suggesting that faults beneath the wrinkle ridges offset the plains. This offset indicates underlying thrust faults that dip to the northwest and west, respectively, and systematically lower the southeast side of the plains. The observation that the elevation offsets across the ridges are maintained to the next ridge implies that the thrust fault penetrates to depths of tens of kilometers and thus well into the mechanical lithosphere

  1. Thermodynamics of feedback controlled systems

    NASA Astrophysics Data System (ADS)

    Cao, F. J.; Feito, M.

    2009-04-01

    We compute the entropy reduction in feedback controlled systems due to the repeated operation of the controller. This was the lacking ingredient to establish the thermodynamics of these systems, and in particular of Maxwell’s demons. We illustrate some of the consequences of our general results by deriving the maximum work that can be extracted from isothermal feedback controlled systems. As a case example, we finally study a simple system that performs an isothermal information-fueled particle pumping.

  2. Bisensory force feedback in telerobotics

    NASA Astrophysics Data System (ADS)

    Williams, Lorraine E. P.

    2001-11-01

    Effectively controlling a robot remotely to perform a desired task---teleoperation---offers benefits in improving human safety, reducing workload, providing location accessibility, and in convenience. Because these benefits become more evident under the extreme environmental conditions of space operations, NASA Johnson Space Center has been actively researching the usage of and improvements in teleoperations. Teleoperator task performance has been shown to improve with the addition of sensory feedback. In particular, providing force-feedback to a human operator, has been shown to decrease task completion times and lessen potentially damaging contact forces between the slave robot and its target work environment. We summarize the design, development, and usage of a human interface system built to provide position control as well as both kinesthetic and visual six-axis force-feedback displays to a human teleoperator of a remote manipulator. The system developed is utilized as an experimentation platform evaluating the merit of providing force feedback through both kinesthetic (muscular position and force) and substituted visual displays on a typical space operations task utilizing an anthropomorphic slave robot called "Robonaut". Teleoperator performance of a drill task is measured under four different display scenarios: no force display, visual force display, kinesthetic, and both. Task completion times and contact forces are measured, and subjective questionnaire responses collected. Our results indicate lower maximum force/torque, lower cumulative force/torque, and a greater task consistency with any type of feedback, with no significant differences in task completion time. Cumulative force/torque was reduced between 46--51% with visually substituted force feedback, 69--81% with kinesthetic feedback and 63--92% with both forms of feedback. Maximum force/torque variance between subjects was reduced between 61--90% with any type of force display, indicating improved

  3. Carslberg Ridge and Mid-Atlantic Ridge: Slow-spreading Apparent Analogs

    NASA Astrophysics Data System (ADS)

    Rona, P. A.; Murton, B. J.; Bostrom, K.; Widenfalk, L.; Melson, W. G.; O'Hearn, T.; Cronan, D. S.; Jenkins, W. J.

    2005-12-01

    We compare morphology, tectonics, petrology, and hydrothermal activity of a known section of the Mid-Atlantic Ridge (MAR) between the Kane and Atlantis fracture zones (full multi-beam coverage 21N to 31N) to the lesser known Carlsberg Ridge (CR; limited multi-beam coverage plus satellite altimetry). The CR extends from the Owen Fracture Zone (10N) to the Vityaz Fracture Zone (5S) and spreads at half-rates (~1.2-1.8 cm/yr) similar to the MAR: 1) Morphology: Both ridges exhibit distinct segmentation (primarily sinistral) and axial valleys with high floor to crest relief (range 1122-1771 m). Average lengths of segments (CR: 70 km; MAR: 50 km) and crest-to crest width of the axial valley are greater on the CR (40 km) than MAR (23 km). Axial volcanic ridges form the neovolcanic zone on both ridges, typically 2.6 km wide and 213 m high on the CR. Average water depth near segment centers is greater on the MAR (3933 m) than the CR (3564 m). V-shaped patterns oblique to the spreading axis are present on both ridges. 2) Tectonics: Segments on each ridge are predominantly separated by short-offset (<30 km) non-transform discontinuities with longer transform faults generally spaced hundreds of kilometers apart. Bulls-eye Mantle Bouguer Lows (-30 to -50 mgal) are present at centers of spreading segments on both ridges. Metamorphic core complexes of lower crust and upper mantle are present on the MAR section (at fracture zones) and at least at one locality at 58.33E on the CR. 3) Petrology: MORB composition from our 20 stations along the CR fall into the MORB family, with no evidence of hotspot inputs (no excess K or Nb), or extreme fractionation, similar to the MAR section. REE and trace element patterns between 57E and 61E on the CR indicate increasing melt depletion to the northwest, while glasses exhibit a striking systematic increase in MgO (decrease in fractionation) to the northwest and attain among the most primitive composition of any ocean ridge adjacent to the Owen

  4. 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.

  5. 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.

  6. 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.

  7. Pristine MORB mantle from Gakkel Ridge

    NASA Astrophysics Data System (ADS)

    Snow, J. E.; Hellebrand, E.

    2010-12-01

    Fresh mantle rocks (Total ~300Kg) have been recovered from three dredge hauls on Gakkel Ridge. Most of the fresh material (~275 Kg) is from a single dredge haul (PS66-238) from PFS POLARSTERN ARK XX/2 in 2004 (not from the AMORE expedition). The samples from this group comprise extremely fresh protogranular lherzolites that have clearly defined 1-2 cm orange weathering rinds. The weathered material seems to be mostly discoloration along grain boundaries, as bulk weathering (e.g. Snow and Dick, 1995) cannot be detected in bulk analyses. The fresh cores are largely devoid of serpentine that can be identified in hand sample or SEM. The samples show a bimodal grain size distribution and abundant polygonization of olivine, but little stretching of pyroxene grains, suggesting that they have not been subject to intense deformation that has been seen in many mid-ocean ridge peridotites. Currently, 14 of the 208 discrete samples have been studied. The major element compositions of these samples range from relatively fertile spinel lherzolites to moderately depleted cpx-bearing harzburgites, both in their bulk chemistry and in the compositions of major minerals. The average Cr# (Dick and Bullen, 1984) of spinel ranges from 0.15 to 0.28, suggesting 5-12% melt extraction (Hellebrand et al. 2001). Trace elements measured by SIMS and LA-ICPMS reveal metasomatism and refertilization of the LREE. Os isotopes vary from 187Os/188Os of 0.128 to 0.114, revealing an ancient component that can be interpreted either as a fertile ambient mantle with a highly depleted ancient exotic block or as a single mantle domain variably depleted in an ancient melting event (Liu et al., 2008). Bulk Li isotopic data correspond to estimates of the MORB mantle, however mineral separates show significant isotopic heterogeneity that appears to be caused by diffusion caused by Li redistribution during uplift and cooling (Gao et al., accepted). The altered samples have radically different textures. These

  8. Human factors in telemanipulation: perspectives from the Oak Ridge National Laboratory experience

    NASA Astrophysics Data System (ADS)

    Draper, John V.

    1993-12-01

    Personnel at the Robotics and Process Systems Division (RPSD) of the Oak Ridge National Laboratory 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.

  9. 75 FR 9406 - Crescent Ridge LLC; Notice of Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-02

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Crescent Ridge LLC; Notice of Filing February 23, 2010. Take notice that on February 16, 2010, Crescent Ridge LLC filed a supplement to its February 2, 2010 section 203...

  10. 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.

  11. 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

  12. Physiographic constraints on the origin of lunar wrinkle ridges

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    Wrinkle ridges are linear asymmetric topographic highs with considerable morphologic complexity that are commonly found on the lunar maria and the smooth plains of Mars and Mercury. The origin of planetary wrinkle ridges has been a much argued and debated topic. Early ideas suggested that wrinkle ridges resulted from volcanic intrusion and extrusion of high viscosity lavas; these early ideas were countered with suggestions that wrinkle ridges formed from tectonic processes involving folding and faulting. Combined volcanic and tectonic mechanisms have also been suggested. The identification and analysis of a number of morphologically similar structures on the earth has helped in the recent interpretation of wrinkle ridges as thrust faults that deform surface rocks. Nevertheless, there remains the uncertainty of the dominant role of thrusting versus folding in the formation of planetary wrinkle ridges. Presented is a detailed physiographic analysis of lunar wrinkle ridges in an effort to help distinguish the dominant deformation mechanism. Results agree with the findings of the earth analog study and support the hypothesis that wrinkle ridges form from thrust faults that deform surface rocks.

  13. 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.

  14. 76 FR 35909 - Temporary Concession Contract for Blue Ridge Parkway

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-20

    ...-OYC] Temporary Concession Contract for Blue Ridge Parkway AGENCY: National Park Service, Interior. ACTION: Notice of proposed award of temporary concession contracts for Blue Ridge Parkway, NC/VA. SUMMARY... award temporary concession contracts for the conduct of certain visitor services within the Blue...

  15. 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

  16. 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)

  17. 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.

  18. Feedback traps for virtual potentials

    NASA Astrophysics Data System (ADS)

    Gavrilov, Momčilo; Bechhoefer, John

    2017-03-01

    Feedback traps are tools for trapping and manipulating single charged objects, such as molecules in solution. An alternative to optical tweezers and other single-molecule techniques, they use feedback to counteract the Brownian motion of a molecule of interest. The trap first acquires information about a molecule's position and then applies an electric feedback force to move the molecule. Since electric forces are stronger than optical forces at small scales, feedback traps are the best way to trap single molecules without `touching' them (e.g. by putting them in a small box or attaching them to a tether). Feedback traps can do more than trap molecules: they can also subject a target object to forces that are calculated to be the gradient of a desired potential function U(x). If the feedback loop is fast enough, it creates a virtual potential whose dynamics will be very close to those of a particle in an actual potential U(x). But because the dynamics are entirely a result of the feedback loop-absent the feedback, there is only an object diffusing in a fluid-we are free to specify and then manipulate in time an arbitrary potential U(x,t). Here, we review recent applications of feedback traps to studies on the fundamental connections between information and thermodynamics, a topic where feedback plays an even more fundamental role. We discuss how recursive maximum-likelihood techniques allow continuous calibration, to compensate for drifts in experiments that last for days. We consider ways to estimate work and heat, using them to measure fluctuating energies to a precision of ±0.03 kT over these long experiments. Finally, we compare work and heat measurements of the costs of information erasure, the Landauer limit of kT ln 2 per bit of information erased. We argue that, when you want to know the average heat transferred to a bath in a long protocol, you should measure instead the average work and then infer the heat using the first law of thermodynamics. This

  19. Structural Responses to the Chile Ridge Subduction, Southern South America

    NASA Astrophysics Data System (ADS)

    Rodriguez, E. E.; Russo, R. M.; Mocanu, V. I.; Gallego, A.; Murdie, R.; Comte, D.

    2015-12-01

    The Nazca-Antarctic plate boundary, the Chile spreading ridge, subducts beneath South America, forming the northward-migrating Chile Triple Junction (CTJ), now at ~46.5°S, where an actively spreading segment is currently in the Nazca trench. Ridge subduction is associated with diachronously developed variable structure and magmatism of overriding South America. To assess the effects of ridge subduction, we deployed a network of 39 broadband seismometers in southern Chile between 43 - 49°S and 71 - 76°W from Dec. 2004 - Feb. 2007, recording 102 earthquakes suitable for receiver function analyses, i.e., M > 5.9, of various backazimuths, and at epicentral distances of 30 - 90°. The network encompassed onland portions of the current triple junction and ridge subduction, areas to the south of the CTJ where ridge segments subducted during the last 6 m.y., and regions north of the CTJ not yet affected by ridge subduction, allowing the assessment of the effects of ridge subduction on crustal structure of overriding South America. We constructed 551 teleseismic receiver functions to estimate crustal thicknesses, H, and average compressional to shear wave velocity ratios, Vp/Vs = k, using the iterative time deconvolution method of Ligorria and Ammon (1999). H and k were calculated using the grid search method of Zhu and Kanamori (2000). Beneath stations closest to the trench, where the Nazca plate subducts, we found Moho depths between 28 and 55 km, thickening northward. At the locus of current ridge subduction, in the Taitao Pennisula, thinner crust ranges from 27 - 36 km. H is 36-38 km where the Antarctic plate subducts and the Chile ridge recently subducted. The direct effect of the subducting ridge on South America can be seen in H differences between forearc regions that have sustained ridge subduction versus those that have not. South American forearc crust above the subducted Nazca plate is as much as 28 km thicker than forearc crust recently affected by ridge

  20. 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

  1. 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

  2. The axial topographic high at intermediate and fast spreading ridges

    NASA Astrophysics Data System (ADS)

    Carbotte, Suzanne M.; MacDonald, Ken C.

    1994-12-01

    An axial topographic high is commonly observed at both fast spreading ridges and some segments of intermediate spreading ridges. At fast rates the axial high is primarily created by the buoyancy of hot rock and magma beneath the rise. As newly formed crust is transported off axis, little vestige of an axial high is observed on the ridge flanks. In contrast, at intermediate rates, a significant component of the positive topography may be a volcanic construction, preserved on the ridge flanks as abyssal hills, which are slit axial volcanoes. We suggest this difference in the nature of the axial high reflects a lithosphere strong enough to support construction of a volcanic crestal ridge at intermediate spreading rates, but only rarely at fast rates. Relict overlap ridges, found within the discordant zones left by overlapping spreading centers, is one class of ridge-flank topography which appears to have a significant volcanic constructional component even at fast spreading ridges. Unlike topography away from these discontinuities, the relief and shape of overlapping spreading centers is preserved as relict ridge tips are rafted onto the ridge flanks. Reduced magma supply at these discontinuities may give rise to an axial lithosphere strong enough to support volcanic construction of overlap ridges. Low axial lithospheric strength may also account for the lack of normal faults within the innermost 1-2 km of fast, and some intermediate, spreading ridges. With a thin/weak brittle layer at the ridge crest, tensile failure will predominate and few normal faults will form. Depths to the axial magma chamber reflector observed in multi-channel seismic data limit the thickness of the brittel layer on axis to less than 1-2 km for much of the East Pacific Rise (EPR). This depth is comparable to depths over which tensile failure within the oceanic crust will predominate, estimated from the Griffith criteria for fracture initiation (approx. 0.5-1.5 km). As the brittle layer

  3. Influence of mid-ocean ridges on Rossby waves

    NASA Technical Reports Server (NTRS)

    Wang, Liping; Koblinsky, C. J.

    1994-01-01

    Influence of mid-ocean ridges on Rossby wave activity is discussed in simple models. Ridges can influence Rossby waves in two ways, topographic scattering to model parameters such as frequency, ridge height, and ridge width in both barotropic and baroclinic models. In the barotropic model, for certain model parameters there is perfect transmission of Rossby waves, while for some other model parameters the transmission is rather weak. In a two-layer model, if the frequency is not low enough, trapping of baroclinic signals around topography will occur. The mid-ocean ridge is generally not as efficient as the eastern boundary in generating barotropic waves except at high frequencies in a barotropic model. It is much more efficient than the eastern boundary generating baroclinic waves when wind forcing has a very large zonal scale, while less efficient when wind forcing has a short zonal scale.

  4. First-order linear tectonovolcanic ridges in oceans

    NASA Astrophysics Data System (ADS)

    Pushcharovsky, Yu. M.

    2011-03-01

    The first-order Line, Hawaiian, Emperor, Pukapuka, Louisville, Ninetyeast, and Chagos-Lackadive tectonovolcanic ridges in the Pacific and Indian oceans are considered. These ridges are combined into the category of demarcation tectonic units separating the largest morphostructural sectors of the oceans. The ridges extend for thousands kilometers and are a few hundred kilometers in width. Their crest zones are crowned by numerous volcanoes. The volcanic rocks are largely basalts with elevated alkalinity. All of the ridges were formed in the Late Cretaceous-Cenozoic; the ages of particular ridges are variable. The dimensions of the demarcation tectonic units allow us to refer them to the processes proceeding in the mantle, including tectonic flow, faulting, and significant strike-slip displacements.

  5. 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.

  6. Efficacy of 230Th normalization in sediments from the Juan de Fuca Ridge, northeast Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Costa, Kassandra; McManus, Jerry

    2017-01-01

    230Th normalization is an indispensable method for reconstructing sedimentation rates and mass fluxes over time, but the validity of this approach has generated considerable debate in the paleoceanographic community. 230Th systematics have been challenged with regards to grain size bias, sediment composition (CaCO3), water column advection, and other processes. In this study, we investigate the consequences of these effects on 230Th normalization from a suite of six cores on the Juan de Fuca Ridge. The proximity of these cores (<30 km) suggests that they should receive the same particle rain rate of sediment, but the steep bathymetry of the ridge leads to substantial sediment redistribution and variable carbonate preservation, both of which may limit the usage of 230Th in this region. Despite anticipated complications, 230Th normalization effectively reconstructs nearly identical particle rain rates from all six cores, which are summarily unrelated to the total sedimentation rates as calculated from the age models. Instead the total sedimentation rates are controlled almost entirely by sediment focusing and winnowing, which are highly variable even over the short spatial scales investigated in this study. Furthermore, no feedbacks on 230Th systematics were detected as a consequence of sediment focusing, coarse fraction variability, or calcium carbonate content, supporting the robustness of the 230Th normalization technique.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Multimedia as a Means to Enhance Feedback

    ERIC Educational Resources Information Center

    Tsutsui, Michio

    2004-01-01

    Interactive feedback, the most common feedback method for oral performance, cannot be used in activities that do not allow for instructor-student interaction, such as speeches and presentations, where feedback should occur after the performance. The conventional ways of providing post-performance or delayed feedback, however, are neither efficient…

  12. 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…

  13. Electromyograph Feedback as a Relaxation Technique

    ERIC Educational Resources Information Center

    Coursey, Robert D.

    1975-01-01

    An electromyograph (EMG) feedback group of 10 normal undergraduate males received variable-tone feedback from the frontalis muscle. Comparisons showed that the feedback group achieved significantly lower EMG scores than the two control groups, but only one of the six measures of state anxiety favored the feedback group over the controls. (Author)

  14. Feedback Dialogues That Stimulate Students' Reflective Thinking

    ERIC Educational Resources Information Center

    Van der Schaaf, Marieke; Baartman, Liesbeth; Prins, Frans; Oosterbaan, Anne; Schaap, Harmen

    2013-01-01

    How can feedback dialogues stimulate students' reflective thinking? This study aims to investigate: (1) the effects of feedback dialogues between teachers and students on students' perceptions of teacher feedback and (2) the relation between features of feedback dialogues and students' thinking activities as part of reflective thinking. A…

  15. 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…

  16. Feedback in Videogame-based Adaptive Training

    DTIC Science & Technology

    2011-05-01

    individuals have limited information processing capabilities. Salvati et al. (2003) identified several antecedents and consequences to feedback overload... Antecedents included feedback value and job experience while important consequences were the desire to respond to feedback, stress, and job...Morin, D. (2003). Performance feedback overload: An exploratory field study of its antecedents and consequences . Montreal, Quebec: HEC Montreal

  17. 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…

  18. 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…

  19. 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…

  20. 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.

  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. 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.

  3. 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.

  4. 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.

  5. Radar and photoclinometric studies of wrinkle ridges on Mars

    USGS Publications Warehouse

    Watters, T.R.; Robinson, M.S.

    1997-01-01

    Earth-based radar altimetry and image derived photoclinometric profiles were analyzed to examine both the long- and short-wavelength topography associated with wrinkle ridges on Mars. Photoclinometrically derived elevation data across wrinkle ridges were evaluated to determine the sensitivity of profiles to two empirical photoclinometric parameters, the horizontal digital number (HDN) and the scattered light value (SLV). The photoclinometric profiles are extremely sensitive to small variations in HDN. The sense of slope of a profile can be completely reversed over a range in HDN of as little as ?? 1. Comparably small variations in the SLV have relatively minor effects on the photoclinometrically derived elevations. The existence of elevation offsets from one side of the ridge to the other, reported in previous photoclinometric studies of martian wrinkles, were not confirmed through photoclinometry. In addition, no evidence of elevation offsets were found in Earth-based radar altimetry profiles across wrinkle ridges. In order to more accurately model wrinkle ridge topography, we controlled photoclinometrically derived elevations with long-wavelength topography obtained from the radar altimetry. The results of this study do not support kinematic models for the origin of planetary wrinkle ridges that involve deeply rooted thrust faults which separate crustal blocks at different elevations. A kinematic model involving buckling of shallow crustal layers into concentric folds that close, leading to the development of thrust faults, is consistent with wrinkle ridge morphology and terrestrial analogs. Recent geophysical studies of terrestrial analogs and the influence of shallow subsurface structures, particularly buried craters, on the localization of many wrinkle ridges on Mars suggest that thrust faults associated with the ridges are confined to the ridged plains material and do not extend into the lithosphere. Copyright 1997 by the American Geophysical Union.

  6. Radar and photoclinometric studies of wrinkle ridges on Mars

    NASA Astrophysics Data System (ADS)

    Watters, Thomas R.; Robinson, Mark S.

    1997-05-01

    Earth-based radar altimetry and image derived photoclinometric profiles were analyzed to examine both the long- and short-wavelength topography associated with wrinkle ridges on Mars. Photoclinometrically derived elevation data across wrinkle ridges were evaluated to determine the sensitivity of profiles to two empirical photoclinometric parameters, the horizontal digital number (HDN) and the scattered light value (SLV). The photoclinometric profiles are extremely sensitive to small variations in HDN. The sense of slope of a profile can be completely reversed over a range in HDN of as little as +/-1. Comparably small variations in the SLV have relatively minor effects on the photoclinometrically derived elevations. The existence of elevation offsets from one side of the ridge to the other, reported in previous photoclinometric studies of martian wrinkles, were not confirmed through photoclinometry. In addition, no evidence of elevation offsets were found in Earth-based radar altimetry profiles across wrinkle ridges. In order to more accurately model wrinkle ridge topography, we controlled photoclinometrically derived elevations with long-wavelength topography obtained from the radar altimetry. The results of this study do not support kinematic models for the origin of planetary wrinkle ridges that involve deeply rooted thrust faults which separate crustal blocks at different elevations. A kinematic model involving buckling of shallow crustal layers into concentric folds that close, leading to the development of thrust faults, is consistent with wrinkle ridge morphology and terrestrial analogs. Recent geophysical studies of terrestrial analogs and the influence of shallow subsurface structures, particularly buried craters, on the localization of many wrinkle ridges on Mars suggest that thrust faults associated with the ridges are confined to the ridged plains material and do not extend into the lithosphere.

  7. 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.

  8. Seismic structure of Cocos and Malpelo Volcanic Ridges and implications for hot spot-ridge interaction

    NASA Astrophysics Data System (ADS)

    SallarèS, Valentí; Charvis, Philippe; Flueh, Ernst R.; Bialas, Joerg

    2003-12-01

    The Cocos and Malpelo Volcanic Ridges are blocks of thickened oceanic crust thought to be the result of the interaction between the Galapagos hot spot and the Cocos-Nazca Spreading Center during the last 20 m.y. In this work we investigate the seismic structure of these two aseismic ridges along three wide-angle transects acquired during the Panama basin and Galapagos plume—New Investigations of Intraplate magmatism (PAGANINI)-1999 experiment. A two-dimensional velocity field with the Moho geometry is obtained using joint refraction/reflection travel time tomography, and the uncertainty and robustness of the results are estimated by performing a Monte Carlo-type analysis. Our results show that the maximum crustal thickness along these profiles ranges from ˜16.5 km (southern Cocos) to ˜19 km (northern Cocos and Malpelo). Oceanic layer 2 thickness is quite uniform regardless of total crustal thickness variations; crustal thickening is mainly accommodated by layer 3. These observations are shown to be consistent with gravity data. The variation of layer 3 velocities is similar along all profiles, being lower where crust is thicker. This leads to an overall anticorrelation between crustal thickness and bulk lower crustal velocity. Since this anticorrelation is contrary to crustal thickening resulting from passive upwelling of abnormally hot mantle, it is necessary to consider active upwelling components and/or some compositional heterogeneities in the mantle source. The NW limit of the Malpelo Ridge shows a dramatic crustal thinning and displays high lower crustal velocities and a poorly defined crust-mantle boundary, suggesting that differential motion along the Coiba transform fault probably separated Regina and Malpelo Ridges.

  9. 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.

  10. 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.

  11. An aerial radiological survey of the Oak Ridge Reservation, Oak Ridge, Tennessee. Date of survey: April 1992

    SciTech Connect

    Maurer, R.J.

    1993-04-01

    An aerial radiological survey of the Oak Ridge Reservation (ORR) and surrounding area in Oak Ridge, Tennessee, was conducted during the period March 30 to April 14,1992. The purpose of the survey was to measure and document the terrestrial radiological environment of the Oak Ridge Reservation for use in environmental management programs and emergency response planning. The aerial survey was flown at an altitude of 150 feet (46 meters) along a series of parallel lines 250 feet (76 meters) apart and included X-10 (Oak Ridge National Laboratory), K-25 (former Gaseous Diffusion Plant), Y-12 (Weapons Production Plant), the Freels Bend Area and Oak Ridge Institute for Science and Education, the East Fork Poplar Creek (100-year floodplain extending from K-25 to Y-12), Elza Gate (former uranium ore storage site located in the city of Oak Ridge), Parcel A, the Clinch River (river banks extending from Melton Hill Dam to the city of Kingston), and the CSX Railroad Tracks (extending from Y-12 to the city of Oak Ridge). The survey encompassed approximately 55 square miles (1 41 square kilometers) of the Oak Ridge Reservation and surrounding area.

  12. 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

  13. 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.

  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. Modification of mandibular ridge splitting technique for horizontal augmentation of atrophic ridges

    PubMed Central

    Abu Tair, Jawad A.

    2014-01-01

    Purpose: A two stage approach of ridge splitting and lateral expansion in the mandible to achieve enough bone width for the purpose of dental implants is presented. Materials and Methods: A total of 13 consecutive patients with 16 long-span edentulous areas of the mandibular ridge were included in this study and 42 dental implants were inserted. Corticotomy of a rectangular buccal segment was carried out followed by 3 weeks of recovery; the mandibular ridge was stretched laterally, leaving the buccal periosteum attached to the lateralized segment. In this modification, there was no need for the use of grafted foreign materials to fill the defect and neither the use of barrier membranes, since it was treated practically as a fresh extraction site. To prevent the undesirable movement of the lateral plate, a small chip (2-3 mm in diameter) of bone spacer was properly fixed. The dental implants were placed 3-5 months later on. Results: Approximately, 86% of the expanded areas were successful in providing an adequate width to accommodate an implant. The average gain in width was 3.22 ± 0.97 mm. All intended implants were inserted. Prosthetic loading with fixed prosthesis was successfully implemented in all cases. Conclusion: This modified technique is a simple and short procedure with satisfactory results and minimal morbidity. Of note, this approach is devoid of foreign materials usage and has a low rate cost, therefore, should be employed more often. PMID:24987593

  16. 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.

  17. 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.

  18. 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

  19. Delayed feedback control of chaos.

    PubMed

    Pyragas, Kestutis

    2006-09-15

    Time-delayed feedback control is well known as a practical method for stabilizing unstable periodic orbits embedded in chaotic attractors. The method is based on applying feedback perturbation proportional to the deviation of the current state of the system from its state one period in the past, so that the control signal vanishes when the stabilization of the target orbit is attained. A brief review on experimental implementations, applications for theoretical models and most important modifications of the method is presented. Recent advancements in the theory, as well as an idea of using an unstable degree of freedom in a feedback loop to avoid a well-known topological limitation of the method, are described in detail.

  20. Klystron equalization for RF feedback

    SciTech Connect

    Corredoura, P.

    1993-01-01

    The next generation of colliding beam storage rings support higher luminosities by significantly increasing the number of bunches and decreasing the spacing between respective bunches. The heavy beam loading requires large RF cavity detuning which drives several lower coupled bunch modes very strongly. One technique which has proven to be very successful in reducing the coupled bunch mode driving impedance is RF feedback around the klystron-cavity combination. The gain and bandwidth of the feedback loop is limited by the group delay around the feedback loop. Existing klystrons on the world market have not been optimized for this application and contribute a large portion of the total loop group delay. This paper describes a technique to reduce klystron group delay by adding an equalizing filter to the klystron RF drive. Such a filter was built and tested on a 500 kill klystron as part of the on going PEP-II R&D effort here at SLAC.

  1. Klystron equalization for RF feedback

    SciTech Connect

    Corredoura, P.

    1993-01-01

    The next generation of colliding beam storage rings support higher luminosities by significantly increasing the number of bunches and decreasing the spacing between respective bunches. The heavy beam loading requires large RF cavity detuning which drives several lower coupled bunch modes very strongly. One technique which has proven to be very successful in reducing the coupled bunch mode driving impedance is RF feedback around the klystron-cavity combination. The gain and bandwidth of the feedback loop is limited by the group delay around the feedback loop. Existing klystrons on the world market have not been optimized for this application and contribute a large portion of the total loop group delay. This paper describes a technique to reduce klystron group delay by adding an equalizing filter to the klystron RF drive. Such a filter was built and tested on a 500 kill klystron as part of the on going PEP-II R D effort here at SLAC.

  2. 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.

  3. 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.

  4. 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).

  5. An ultrasonic linear motor using ridge-mode traveling waves.

    PubMed

    Tominaga, Masahiko; Kaminaga, Ryuta; Friend, James R; Nakamura, Kentaro; Ueha, Sadayuki

    2005-10-01

    A new type of ultrasonic linear motor is presented using traveling waves excited along a ridge atop a substrate. The ridge cross section was designed to permit only the fundamental mode to be excited during operation of the motor, with a Langevin transducer used as the source of vibration in this study. The ridge waveguide was first made of lossy media to avoid reflecting vibration energy back toward the vibration source, forming a traveling wave. A 5-mm-wide, 15-mm-tall rectangular acrylic ridge was used to move a slider placed upon it toward the vibration source, in opposition to the direction of the traveling wave transmitted along the waveguide ridge. Using a low-loss 3 x 6-mm aluminum rectangular ridge combined with a damper clamped onto the far end of the waveguide, similar results were obtained. To obtain bidirectional operation, the damper was replaced with a second Langevin transducer, giving a pair of transducers located perpendicularly to the ends of the ridge and driven with an appropriate phase difference. The moving direction of the slider was reversed by shifting this phase difference by about 180 degrees. With this simple configuration, it may soon be possible to fabricate a linear micromotor system on a silicon substrate or other semiconductor wafer adjacent to other electronic and optoelectronic devices.

  6. Propagating buoyant mantle upwelling on the Reykjanes Ridge

    NASA Astrophysics Data System (ADS)

    Martinez, Fernando; Hey, Richard

    2017-01-01

    Crustal features of the Reykjanes Ridge have been attributed to mantle plume flow radiating outward from the Iceland hotspot. This model requires very rapid mantle upwelling and a "rheological boundary" at the solidus to deflect plume material laterally and prevent extreme melting above the plume stem. Here we propose an alternative explanation in which shallow buoyant mantle upwelling instabilities propagate along axis to form the crustal features of the ridge and flanks. As only the locus of buoyant upwelling propagates this mechanism removes the need for rapid mantle plume flow. Based on new geophysical mapping we show that a persistent sub-axial low viscosity channel supporting buoyant mantle upwelling can explain the current oblique geometry of the ridge as a reestablishment of its original configuration following an abrupt change in opening direction. This mechanism further explains the replacement of ridge-orthogonal crustal segmentation with V-shaped crustal ridges and troughs. Our findings indicate that crustal features of the Reykjanes Ridge and flanks are formed by shallow buoyant mantle instabilities, fundamentally like at other slow spreading ridges, and need not reflect deep mantle plume flow.

  7. 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.

  8. Geophysical Characteristics of the Australian-Antarctic Ridge

    NASA Astrophysics Data System (ADS)

    Kim, S. S.; Lin, J.; Park, S. H.; Choi, H.; Lee, S. M.

    2014-12-01

    Between 2011 and 2013, the Korea Polar Research Institute (KOPRI) conducted three consecutive geologic surveys at the little explored eastern ends of the Australian-Antarctic Ridge (AAR) to characterize the tectonics, geochemistry, and hydrothermal activity of this intermediate spreading system. Using the Korean icebreaker R/V Araon, the multi-disciplinary research team collected bathymetry, gravity, magnetics, and rock and water column samples. In addition, Miniature Autonomous Plume Recorders (MAPRs) were deployed at wax-core rock sampling sites to detect the presence of active hydrothermal vents. Here we present a detailed analysis of a 300-km-long supersegment of the AAR to quantify the spatial variations in ridge morphology and robust axial and off-axis volcanisms. The ridge axis morphology alternates between rift valleys and axial highs within relatively short ridge segments. To obtain a geological proxy for regional variations in magma supply, we calculated residual mantle Bouguer gravity anomalies (RMBA), gravity-derived crustal thickness, and residual topography for seven sub-segments. The results of the analyses revealed that the southern flank of the AAR is associated with shallower seafloor, more negative RMBA, thicker crust, and/or less dense mantle than the conjugate northern flank. Furthermore, this north-south asymmetry becomes more prominent toward the KR1 supersegment of the AAR. The axial topography of the KR1 supersegment exhibits a sharp transition from axial highs at the western end to rift valleys at the eastern end, with regions of axial highs being associated with more magma supply as indicated by more negative RMBA. We also compare and contrast the characteristics of the AAR supersegment with that of other ridges of intermediate spreading rates, including the Juan de Fuca Ridge, Galápagos Spreading Center, and Southeast Indian Ridge west of the Australian-Antarctic Discordance, to investigate the influence of ridge-hotspot interaction on

  9. 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

  10. 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

  11. 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

  12. Physical Volcanology of the Huckleberry Ridge Tuff

    NASA Astrophysics Data System (ADS)

    Wilson, C. J.

    2009-12-01

    The 2.06 Ma Huckleberry Ridge Tuff, product of the oldest and largest (ca. 2500 cubic km) of the three caldera-forming eruptions from the Yellowstone system, consists of three major ignimbrite units (A, B, C) with underlying and intervening fall deposits. Despite intense welding, and subsequent significant faulting and erosion, the broad characteristics of the deposits provide valuable insights into the eruption dynamics. Field evidence shows unambiguously that the eruption was spasmodic and prolonged, in addition to complexities previously recognised in vent locations and eruptive compositions by R.L. Christiansen (US Geological Survey Professional Paper 729-G, 2001). The initial fall activity, although plinian in dispersal, was not exceptionally powerful or unusual in any respect, and gives no obvious hints of the scale of what was to follow. This initial fall activity was also prolonged, possibly over months, during which time intrafall reworking occurred at several stages. Ignimbrite unit A is much the largest in volume, and represents most of the thickness of tuff southwest of the caldera, including the rheomorphic tuff of Big Bend Ridge previously mapped as B. Units A and B are separated by weeks or more, based on cooling breaks, and units B and C separated by years or more, based on breaks in cooling and degassing histories. The fall deposit separating ignimbrite units B and C also was erupted spasmodically. Vent-derived lithics in the ignimbrite units are generally mm to cm across, and no coarse lithic-rich facies have been found in units A or B to indicate close proximity to caldera margins. There is also a diversity of juvenile ejecta: red-brown scoria, coarsely porphyritic dense juvenile clasts and their granophyric equivalents, and rhyolitic pumices of a great variety of textures and crystal contents. The overall tuff represents the product of three large and many other small events daisy-chained together and prolonged over a period of probably years to

  13. Solar cell with doped groove regions separated by ridges

    DOEpatents

    Molesa, Steven Edward; Pass, Thomas; Kraft, Steve

    2017-01-31

    Solar cells with doped groove regions separated by ridges and methods of fabricating solar cells are described. In an example, a solar cell includes a substrate having a surface with a plurality of grooves and ridges. A first doped region of a first conductivity type is disposed in a first of the grooves. A second doped region of a second conductivity type, opposite the first conductivity type, is disposed in a second of the grooves. The first and second grooves are separated by one of the ridges.

  14. Reducing geometric dilution of precision using ridge regression signal processing

    NASA Astrophysics Data System (ADS)

    Kelly, R. J.

    The authors propose a method for reducing the effects of GDOP (geometric dilution of precision) in position-fix navigation systems. The idea is to incorporate ridge regression into the aircraft navigation signal processor. MSE (mean square error) performance of an ordinary LMS (least mean square) signal processor was compared with one using ridge regression. Computer simulations confirmed the theory that variance inflation caused by GDOP can be measurably reduced by the ridge regression algorithm. The technique is applicable not only to DME/DME (distance measuring equipment) and GPS but applies also to any position-fix navigation aid, e.g. Loran-C, Omega, and JTIDS relative navigation.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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)

  2. 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…

  3. 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.

  4. 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…

  5. 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…

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. The Equatorial Ridges of Pan and Atlas: Terminal Accretionary Ornaments?

    NASA Astrophysics Data System (ADS)

    Charnoz, Sébastien; Brahic, André; Thomas, Peter C.; Porco, Carolyn C.

    2007-12-01

    In the outer regions of Saturn’s main rings, strong tidal forces balance gravitational accretion processes. Thus, unusual phenomena may be expected there. The Cassini spacecraft has recently revealed the strange “flying saucer” shape of two small satellites, Pan and Atlas, located in this region, showing prominent equatorial ridges. The accretion of ring particles onto the equatorial surfaces of already-formed bodies embedded in the rings may explain the formation of the ridges. This ridge formation process is in good agreement with detailed Cassini images showing differences between rough polar and smooth equatorial terrains. We propose that Pan and Atlas ridges are kilometers-thick “ring-particle piles” formed after the satellites themselves and after the flattening of the rings but before the complete depletion of ring material from their surroundings.

  16. Marathon Oil Company – Circle Ridge NPDES Permit

    EPA Pesticide Factsheets

    Under NPDES permit WY-0000949, the Marathon Oil Company – Circle Ridge is authorized to discharge from its wastewater treatment facility located in Fremont County, Wyoming to a tributary to Coal Draw.

  17. Basaltic Pressure Ridges: Formation and Relationship to Flow Emplacement

    NASA Technical Reports Server (NTRS)

    Theilig, E.

    1985-01-01

    Pressure ridges and pressure plateau are common but not ubiquitous surface features on terrestrial basaltic lava flows and may reflect a specific flow emplacement mechanism. Many of the ridges are large enough to be detected on high-resolution orbital images; therefore, understanding these features could provide a means for interpreting volcanic flows on the mechanism of pressure ridge formation and how their formation relates to flow emplacement. Results from detailed field studies indicate that pressure ridges and plateaus: (1) are emplaced as individual flow lobes, (2) can be composed of primary or secondary material, (3) are dependent on duration and volume of activity within the flow unit, (4) are penecontemporaneous in formation, and (5) are indicative of slowly advancing flows with numerous flow lobes continuously forming and overriding each other.

  18. 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)

  19. 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

  20. Wrinkle ridges, stress domains, and kinematics of venusian plains

    NASA Technical Reports Server (NTRS)

    Mcgill, George E.

    1993-01-01

    Wrinkle ridges are nearly ubiquitous landforms on the plains of Venus. By analogy with similar structures on other planets, venusian wrinkle ridges are inferred to trend normal to the direction of maximum principal compression in the crust, an inference that is verified by geometrical relationships with positive and negative relief features on Venus. Because plains are the dominant terrain on Venus, wrinkle ridges provide an excellent opportunity to determine the orientations of shallow crustal principal stress trajectories over most of the planet. In most places there are two or more sets of wrinkle ridges, and commonly one of these persists over a large area, defining a regional stress domain. Intersection relationships indicate that these domains differ in age.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. Geoid anomalies over Gorringe Ridge, North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Souriau, A.

    1984-04-01

    The geoid anomalies over Gorringe Ridge, a very prominent high in the topography north of the Azores-Gibraltar plate boundary, have been deduced from Seasat alimetric data, and an interpretation of these anomalies together with the gravity anomalies is attempted. The geoid anomalies generated by the topographic high alone with the serpentinite density nearly fit the observed geoid anomalies, so that the structure must be either out of isostatic equilibrium or compensated at great depth. It is shown that a model in isostatic equilibrium with a small negative density contrast extending to 60 km depth or more explains both the gravity and geoid anomalies and is compatible with the deep seismicity north of Gorringe Ridge. Previous nonisostatic models, one involving an uplift of the upper mantle beneath the ridge, one describing a nascent subduction zone, and another involving flexure of the elastic part of the lithosphere due to the ridge loading, are discussed.

  6. 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.

  7. Nested Paleozoic "successor" basins in the southern Appalachian Blue Ridge

    NASA Astrophysics Data System (ADS)

    Tull, James F.; Groszos, Mark 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.

  8. View of Lake Sabrina Dam upstream face from ridge showing ...

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

    View of Lake Sabrina Dam upstream face from ridge showing spillway at lower right of photo, view southwest - Bishop Creek Hydroelectric System, Plant 2, Lake Sabrina Dam, Bishop Creek, Bishop, Inyo County, CA

  9. 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.

  10. 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.

  11. 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.

  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. 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

  14. 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.

  15. 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.

  16. 77 FR 24976 - Environmental Impact Statement for the Proposed Wheatgrass Ridge Wind Project, Fort Hall Indian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-26

    ... Bureau of Indian Affairs Environmental Impact Statement for the Proposed Wheatgrass Ridge Wind Project... on the Environmental Impact Statement (EIS) for the proposed Wheatgrass Ridge Wind Project on the... EIS because the proponent of the Wheatgrass Ridge Wind Project, the Wheatgrass Ridge Wind, LLC.,...

  17. 78 FR 44942 - Environmental Management Site-Specific Advisory Board, Oak Ridge Reservation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-25

    ... 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... Coordinator, Department of Energy Oak Ridge Operations Office, P.O. Box 2001, EM-90, Oak Ridge, TN...

  18. 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...

  19. 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)...

  20. 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.

  1. 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.

  2. Alveolar Ridge Split Technique Using Piezosurgery with Specially Designed Tips

    PubMed Central

    Moro, Alessandro; Foresta, Enrico; Falchi, Marco; De Angelis, Paolo; D'Amato, Giuseppe; Pelo, Sandro

    2017-01-01

    The treatment of patients with atrophic ridge who need prosthetic rehabilitation is a common problem in oral and maxillofacial surgery. Among the various techniques introduced for the expansion of alveolar ridges with a horizontal bone deficit is the alveolar ridge split technique. The aim of this article is to give a description of some new tips that have been specifically designed for the treatment of atrophic ridges with transversal bone deficit. A two-step piezosurgical split technique is also described, based on specific osteotomies of the vestibular cortex and the use of a mandibular ramus graft as interpositional graft. A total of 15 patients were treated with the proposed new tips by our department. All the expanded areas were successful in providing an adequate width and height to insert implants according to the prosthetic plan and the proposed tips allowed obtaining the most from the alveolar ridge split technique and piezosurgery. These tips have made alveolar ridge split technique simple, safe, and effective for the treatment of horizontal and vertical bone defects. Furthermore the proposed piezosurgical split technique allows obtaining horizontal and vertical bone augmentation. PMID:28246596

  3. 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.

  4. 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.

  5. Terrestrial ecosystem feedbacks to global climate change

    SciTech Connect

    Lashof, D.A.; DeAngelo, B.J.; Saleska, S.R.; Harte, J.

    1997-12-31

    Anthropogenic greenhouse gases are expected to induce changes in global climate that can alter ecosystems in ways that, in turn, may further affect climate. Such climate-ecosystem interactions can generate either positive or negative feedbacks to the climate system, thereby either enhancing or diminishing the magnitude of global climate change. Important terrestrial feedback mechanisms include CO{sub 2} fertilization (negative feedbacks), carbon storage in vegetation and soils (positive and negative feedbacks), vegetation albedo (positive feedbacks), and peatland methane emissions (positive and negative feedbacks). While the processes involved are complex, not readily quantifiable, and demonstrate both positive and negative feedback potential, the authors conclude that the combined effect of the feedback mechanisms reviewed here will likely amplify climate change relative to current projections that have not yet adequately incorporated these mechanisms. 162 refs., 7 figs., 3 tabs.

  6. Investigating shareable feedback tags for programming assignments

    NASA Astrophysics Data System (ADS)

    Cummins, Stephen; Burd, Liz; Hatch, Andrew

    2011-03-01

    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 feedback. Results indicate that students with both the lower and higher marks in a cohort are more likely to opt to share their feedback and programming work than students with mid-ranged marks. A variety of reasons, both for and against sharing, given by students are discussed. Six categories of student behaviour exhibited during interaction with their feedback have been identified in this article. This article has shown that feedback tags can be used successfully as a form of shareable feedback and that a number of future research possibilities exist that can extend this topic.

  7. Quality assurance plan for Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1994-01-01

    This Quality Assurance Plan (QAP) is concerned with design and construction (Sect. 2) and characterization and monitoring (Sect. 3). The basis for Sect. 2 is the Quality Assurance Plan for the Design and Construction of Waste Area Grouping 6 Closure at Oak Ridge National Laboratory, Oak Ridge, Tennessee, and the basis for Sect. 3 is the Environmental Restoration Quality Program Plan. Combining the two areas into one plan gives a single, overall document that explains the requirements and from which the individual QAPs and quality assurance project plans can be written. The Waste Area Grouping (WAG) 6 QAP establishes the procedures and requirements to be implemented for control of quality-related activities for the WAG 6 project. Quality Assurance (QA) activities are subject to requirements detailed in the Martin Marietta Energy Systems, Inc. (Energy Systems), QA Program and the Environmental Restoration (ER) QA Program, as well as to other quality requirements. These activities may be performed by Energy Systems organizations, subcontractors to Energy Systems, and architect-engineer (A-E) under prime contract to the US Department of Energy (DOE), or a construction manager under prime contract to DOE. This plan specifies the overall Energy Systems quality requirements for the project. The WAG 6 QAP will be supplemented by subproject QAPs that will identify additional requirements pertaining to each subproject.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Toward Harnessing User Feedback For Machine Learning

    DTIC Science & Technology

    2006-10-02

    feedback and to understand what kinds of feedback users could give . Users were shown explanations of machine learning predictions and asked to provide... learning algorithm. The results show that user feedback has the potential to significantly improve machine learning systems, but that learning ...machine learning predictions and asked to provide feedback to improve the predictions. We found that users had no difficulty providing generous amounts

  13. 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.

  14. 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…

  15. 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…

  16. 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…

  17. 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…

  18. Why Receiving Feedback Collides with Self Determination

    ERIC Educational Resources Information Center

    ten Cate, Olle Th. J.

    2013-01-01

    Providing feedback to trainees in clinical settings is considered important for development and acquisition of skill. Despite recommendations how to provide feedback that have appeared in the literature, research shows that its effectiveness is often disappointing. To understand why receiving feedback is more difficult than it appears, this paper…

  19. 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…

  20. 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.

  1. 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…

  2. 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'…

  3. 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…

  4. The Positive Impact of Negative Feedback

    DTIC Science & Technology

    2011-03-01

    supervisors, subordinates, and peers prior to course start. Following the FRLM lesson on day five, students received individual feedback reports based...Additionally, Nowack (2009) identified where managers who received a small amount of unfavorable feedback actually improved their performance...their arrival at Squadron Officer School, students received a web-based 360-degree feedback survey. Once students completed the surveys, identical

  5. Morphodynamics and slope stability at Mergui Ridge, off western Thailand

    NASA Astrophysics Data System (ADS)

    Schwab, J.; Gross, F.; Krastel, S.; Jintasaeranee, P.; Bunsomboonsakul, S.; Winkelmann, D.; Weinrebe, W.

    2012-04-01

    2D seismic data from the top and the western slope of the Mergui Ridge (200 km off the Thai west coast) have been acquired during MASS cruise III in January 2011 in water depths between 300 and 2200 m. The Mergui Ridge is a part of the outer shelf slope off the Thai-Malay Peninsula and forms the eastern boundary of the East Andaman Basin. Structural features in the working area include faulted older slope sediments at the transition from Mergui Ridge to East Andaman Basin that are onlapping on the (acoustic) basement of Mergui Ridge. At their top these sediments are bordered by a pronounced erosive unconformity. Younger sedimentary units on top include three E-W elongated carbonate platforms. Moreover, drift sediments are deposited on top of the ridge, comprising features such as large scale sediment waves and moats around the platforms indicating transport and reworking of the sediments. These sediments are thinning towards the edge of the ridge where a zone of non-sedimentation prevails. In the East Andaman Basin younger sediments comprise disturbed and partially faulted units that are overlain by plastered drifts with increasing thickness towards south, where pronounced sediment waves within the drifts may indicate slope normal sediment transport by bottom currents. At the basin ridge transition, within the drift sediments on top of Mergui Ridge, and at the edge of the ridge several smaller scale mass transport deposits were identified. These MTDs indicate a general instability of the slope. Instability and general morphology of the slope may result from long-term tectonic processes such as extension due to backarc basin formation in the Andaman Sea basin. Moreover, phases of uplift, erosion and subsidence may have contributed to faulting and deformation of older units in our working area. Ongoing tectonics might still cause deformation and instability. In addition, bottom currents may presently play an important role concerning morphodynamic development by

  6. The structure of the Lomonosov Ridge, Arctic Ocean (Invited)

    NASA Astrophysics Data System (ADS)

    Jackson, H. R.; Marcussen, C.; Funck, T.; Jakobsson, M.; Hell, B.

    2010-12-01

    During the last several years new bathymetric, seismic reflection and refraction profiles have been collected on the Lomonosov Ridge, a feature whose bathymetric expression is 1700 km long and 50-200 km across. Compiling of data from various organizations provides a more complete data base for describing and interpreting the geological history of this unique ridge that crossed the Arctic Ocean from the continental margin of North America (north of Ellesmere Island and Greenland) to the continental margin of Russia creating the Eurasia and Amerasia basins. The Lomonosov Ridge has been described as a double-sided continental margin. Although the conjugate margin on the Eurasia Basin is accepted to be the margin of the Barents and Kara seas, that on the Amerasia Basin side is more difficult to locate. Near the junction of the Ridge with the North American continental margin, new bathymetric data more accurately describe the transition and the variation in slopes on either side of the ridge. On the Eurasia Basin rifted margin, conjugate to the margin of the Barents Sea, many small elongate highs are seen that are not observed on the Amerasia side. The wide plateau on the Lomonosov Ridge near the North American margin has been crossed by short reflection profiles and longer deep refraction profiles. The crustal structure and magnetic signature suggest that the plateau has been altered by igneous intrusion. Between the Pole and the North American margin, based on the magnetic character and supported by a few seismic profiles the continental ridge seems to have been modified by volcanism. This is consistent with the distribution of the High Arctic large igneous province (HALIP) from Franz Josef Land, Svalbard and Greenland (on the conjugate margin prior to rifting) and in the Canadian Arctic Archipelago. The HALIP has a number of radiating dykes that are useful is for the reconstruction of the region prior to sea floor spreading. From the Pole to the Siberian margin of

  7. The Global Distribution of Wrinkle Ridges on Venus

    NASA Astrophysics Data System (ADS)

    Bilotti, Frank; Suppe, John

    1999-05-01

    New digital mapping of over 65,000 wrinkle ridges of the plains of Venus shows a strong correlation between the location and orientation of these long, low-amplitude compressive anticlines and major features of the geoid and long-wavelength topography. Regions with wrinkle ridges occupy 43% of the plains and are strongly skewed toward low elevations and negative geoid anomalies. About 93% of the wrinkle ridge plains lie below mean planetary radius and 72% have negative geoid anomalies. In contrast, the extensional rift zones of Venus are strongly skewed toward high elevations and positive geoid anomalies. Thus compressive deformation dominates the topographic and geoid lows, whereas extensional rifting is generally restricted to the highs. These observations are consistent with geoid-based stress models that predict compression in geoid lows and extension in geoid highs. The orientations of wrinkle ridges are generally consistent over regions extending for 1000-10,000 km. Many regions have multiple sets of wrinkle ridges of different orientations reflecting multiple episodes and directions of compression; however, about 80% of the regions display a single dominant wrinkle ridge orientation, with secondary orientations subordinate. The dominant wrinkle ridge orientations in many regions follow the contours of long-wavelength topography and geoid or lie along the axes of troughs in the geoid. Thus the maximum horizontal compression recorded by the folds is commonly parallel to the present-day gradient in geoid and topography, although some regions are strong exceptions, perhaps reflecting changes in topography and geoid with time. The dominant wrinkle ridge trends ring several major geoid and topographic swells, especially Western Aphrodite Terra and Lada Terra, with ring diameters of 75-120° (8000-13,000 km). In addition there are smaller rings of wrinkle ridges around the swells in Themis, Eistla, and Bell regiones, especially Gula Mons, with ring diameters of 25

  8. Student Feedback Sensitivity and the Efficacy of Feedback Interventions in Public Speaking Performance Improvement

    ERIC Educational Resources Information Center

    Smith, Camille; King, Paul

    2004-01-01

    Although feedback from teachers to students occupies a central role in learning and instruction, the manner in which feedback functions in performance improvement remains unclear. The current study examined how students' sensitivity to feedback and variations in the wording of feedback messages impacted public speaking performance. Results…

  9. The Nature of Feedback: How Different Types of Peer Feedback Affect Writing Performance

    ERIC Educational Resources Information Center

    Nelson, Melissa M.; Schunn, Christian D.

    2009-01-01

    Although providing feedback is commonly practiced in education, there is no general agreement regarding what type of feedback is most helpful and why it is helpful. This study examined the relationship between various types of feedback, potential internal mediators, and the likelihood of implementing feedback. Five main predictions were developed…

  10. Interpreting Feedback: A Discourse Analysis of Teacher Feedback and Student Identity

    ERIC Educational Resources Information Center

    Torres, J. T.; Anguiano, Carlos J.

    2016-01-01

    Feedback has typically been studied as a means of improving academic performance. Few studies inquire into the processes by which feedback shapes student identity. The authors carry out a discourse analysis of written comments to explore how feedback is discursively constructed by both teachers and students. Analysis of written feedback,…

  11. 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 feedback…

  12. Random distributed feedback fibre lasers

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  13. Research on output feedback control

    NASA Technical Reports Server (NTRS)

    Calise, A. J.; Kramer, F. S.

    1985-01-01

    In designing fixed order compensators, an output feedback formulation has been adopted by suitably augmenting the system description to include the compensator states. However, the minimization of the performance index over the range of possible compensator descriptions was impeded due to the nonuniqueness of the compensator transfer function. A controller canonical form of the compensator was chosen to reduce the number of free parameters to its minimal number in the optimization. In the MIMO case, the controller form requires a prespecified set of ascending controllability indices. This constraint on the compensator structure is rather innocuous in relation to the increase in convergence rate of the optimization. Moreover, the controller form is easily relatable to a unique controller transfer function description. This structure of the compensator does not require penalizing the compensator states for a nonzero or coupled solution, a problem that occurs when following a standard output feedback synthesis formulation.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Ultraslow Ridges through Binoculars: Teleseismic Earthquake Characteristics Illuminate Accretion Processes

    NASA Astrophysics Data System (ADS)

    Schlindwein, V.; Laederach, C.; Korger, E.

    2011-12-01

    Ultraslow spreading ridges with full spreading rates < 20 mm/y constitute the largest portion of the global mid-ocean ridge system, yet 85% of these ridges are still unexplored. Understanding the structure and dynamics of crustal production and the associated hydrothermal systems including their biota has become a major challenge of modern mid-ocean ridge research. The complex interplay between tectonic, magmatic and hydrothermal processes that governs lithospheric accretion at ultraslow-spreading ridges is so poorly investigated because their main representatives, the Arctic ridge system and the Southwest Indian Ridge (SWIR), are situated in remote areas with difficult working conditions. While local seismicity studies with ocean bottom seismometers on slow and fast spreading ridges have greatly contributed to our understanding of active accretion processes, comparable studies are lacking for ultraslow spreading ridges forcing to fall back on studies of larger earthquakes recorded on land. Using teleseismic data from the Bulletin of the International Seismological Centre between the years 1976 and 2010, we performed a systematic analysis of the ridge related seismicity (M > 4) of the ultraslow spreading Arctic ridge system and the SWIR. These ridges were divided in 11 sections of uniform seismological, topographic and geological characteristics, totalling a length of 7200 km with the rift axis defined as a multisegment line along the topographic low of the rift valley. Only events within 30 km of the rift axis were included in our study. We found that magmatic and amagmatic accretion sections cannot be distinguished neither by event rate, moment release rate, maximum earthquake magnitude, nor by the b-value. Yet using single link cluster analysis for identification of swarms of 8 or more earthquakes, small clusters of 2-7 earthquakes and single events, we found that sections with amagmatic accretion lack swarms and show consistently a high percentage of single

  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. 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. Evidence for chemically heterogeneous Arctic mantle beneath the Gakkel Ridge

    NASA Astrophysics Data System (ADS)

    D'Errico, Megan E.; Warren, Jessica M.; Godard, Marguerite

    2016-02-01

    Ultraslow spreading at mid-ocean ridges limits melting due to on-axis conductive cooling, leading to the prediction that peridotites from these ridges are relatively fertile. To test this, we examined abyssal peridotites from the Gakkel Ridge, the slowest spreading ridge in the global ocean ridge system. Major and trace element concentrations in pyroxene and olivine minerals are reported for 14 dredged abyssal peridotite samples from the Sparsely Magmatic (SMZ) and Eastern Volcanic (EVZ) Zones. We observe large compositional variations among peridotites from the same dredge and among dredges in close proximity to each other. Modeling of lherzolite trace element compositions indicates varying degrees of non-modal fractional mantle melting, whereas most harzburgite samples require open-system melting involving interaction with a percolating melt. All peridotite chemistry suggests significant melting that would generate a thick crust, which is inconsistent with geophysical observations at Gakkel Ridge. The refractory harzburgites and thin overlying oceanic crust are best explained by low present-day melting of a previously melted heterogeneous mantle. Observed peridotite compositional variations and evidence for melt infiltration demonstrates that fertile mantle components are present and co-existing with infertile mantle components. Melt generated in the Gakkel mantle becomes trapped on short length-scales, which produces selective enrichments in very incompatible rare earth elements. Melt migration and extraction may be significantly controlled by the thick lithosphere induced by cooling at such slow spreading rates. We propose the heterogeneous mantle that exists beneath Gakkel Ridge is the consequence of ancient melting, combined with subsequent melt percolation and entrapment. Initial modes of depleted mantle composition from Hellebrand et al. (2002b). Melt compositions are from Brunelli et al. (2014) in

  2. Pesticide Leaching from Agricultural Fields with Ridges and Furrows.

    PubMed

    Leistra, Minze; Boesten, Jos J T I

    2010-11-01

    In the evaluation of the risk of pesticide leaching to groundwater, the soil surface is usually assumed to be level, although important crops like potato are grown on ridges. A fraction of the water from rainfall and sprinkler irrigation may flow along the soil surface from the ridges to the furrows, thus bringing about an extra load of water and pesticide on the furrow soil. A survey of the literature reveals that surface-runoff from ridges to furrows is a well-known phenomenon but that hardly any data are available on the quantities of water and pesticide involved. On the basis of a field experiment with additional sprinkler irrigation, computer simulations were carried out with the Pesticide Emission Assessment at Regional and Local scales model for separate ridge and furrow systems in a humic sandy potato field. Breakthrough curves of bromide ion (as a tracer for water flow) and carbofuran (as example pesticide) were calculated for 1-m depth in the field. Bromide ion leached comparatively fast from the furrow system, while leaching from the ridge system was slower showing a maximum concentration of about half of that for the furrow system. Carbofuran breakthrough from the furrow system began about a month after application and increased steadily to substantial concentrations. Because the transport time of carbofuran in the ridge soil was much longer, no breakthrough occurred in the growing season. The maximum concentration of carbofuran leaching from the ridge-furrow field was computed to be a factor of six times as high as that computed for the corresponding level field. The study shows that the risk of leaching of pesticides via the furrow soil can be substantially higher than that via the corresponding level field soil.

  3. Tectonic control on deltaic cyclicity in the Ridge Basin, California

    SciTech Connect

    Ehman, K.D.; Sullivan, M.D.; May, S.R. )

    1994-04-01

    Upper Miocene sedimentary rocks of the Ridge basin provide an opportunity to evaluate the relationship between tectonics, subsidence history, and basin fill in an extensional strike-slip setting. Cyclicity of strata within the Ridge basin, which is expressed by the progradational members of the Ridge Route Formation and retrogradation within the Violin Breccia, records sedimentological response to basin margin faulting and variations in accomodation. This cyclicity is best developed within the members of the Peace Valley Formation where thick shaly lacustrine packages are punctuated by progradational sandy fluvial-deltaic units of the Ridge Route Formation. A geohistory curve constructed for the lower portion of the Ridge Basin Group based on magnetostratigraphic age control shows high rates of accomodation with dramatic changes in the interval subsidence rate. There is a significant correlation between increases in subsidence rate and the deposition of thick lacustrine shales in the basin axis and coeval progradation of the Violin Breccia along the western margin of the basin. The Violin Breccia strata were deposited contemporaneously with movement along the San Gabriel fault, and during periods of increased faulting, it prograded into the basin in response to higher sedimentation rates associated with erosion of the uplifted footwall (high relief margin). Progradational intervals of the Violin Breccia, which correspond to the highest rates of subsidence within the basin, are out of phase with the progradation of the sand-prone members of the Ridge Route Formation being derived from the east (low relief margin) during periods of lower subsidence rate. Decreases of subsidence rate generally correspond to periods of progradation of the sandstone members of the Ridge Route Formation and retrogradation of the Violin Breccia until the next period of tectonic subsidence which starts the cycle over again.

  4. 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.

  5. Quality assurance project plan for the Chestnut Ridge Fly Ash Pond Stabilization Project at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    1996-07-01

    The Chestnut Ridge Fly Ash Pond Stabilization (CRFAPS) Project will stabilize a 19-m-high (62-ft-high) earthen embankment across Upper McCoy Branch situated along the southern slope of Chestnut Ridge. This task will be accomplished by raising the crest of the embankment, reinforcing the face of the embankment, removing trees from the face and top of the embankment, and repairing the emergency spillway. The primary responsibilities of the team members are: Lockheed Martin Energy Systems, Inc., (Energy Systems) will be responsible for project integration, technical support, Title 3 field support, environmental oversight, and quality assurance (QA) oversight of the project; Foster Wheeler Environmental Corporation (FWENC) will be responsible for design and home office Title 3 support; MK-Ferguson of Oak Ridge Company (MK-F) will be responsible for health and safety, construction, and procurement of construction materials. Each of the team members has a QA program approved by the US Department of Energy (DOE) Oak Ridge Operations. This project-specific QA project plan (QAPP), which is applicable to all project activities, identifies and integrates the specific QA requirements from the participant`s QA programs that are necessary for this project.

  6. Best management practices plan for the Chestnut Ridge-Filled Coal Ash Pond at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    1996-05-01

    The Chestnut Ridge Filled Coal Ash Pond (FCAP) Project has been established to satisfy Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) requirements for the Chestnut Ridge Operable Unit 2. FCAP is on Chestnut Ridge, approximately 0.5 miles south of the Y-12 Plant. A 62-foot high earthen dam across Upper McCoy Branch was constructed in 1955 to create a pond to serve as a settling basin for fly and bottom ashes generated by burning coal at the Y-12 Steam Plant. Ash from the steam was mixed with water to form a slurry and then pumped to the crest of Chestnut Ridge and released through a large pipe to flow across the Sluice Channel area and into the pond. The ash slurry eventually overtopped the dam and flowed along Upper McCoy Branch to Rogers Quarry. The purpose of this document is to provide a site-specific Best Management Practices (BMP) Plan for construction associated with environmental restoration activities at the FCAP Site.

  7. 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.

  8. How vegetation and sediment transport feedbacks drive landscape change in the Everglades and wetlands worldwide

    USGS Publications Warehouse

    Larsen, Laurel G.; Harvey, Judson W.

    2010-01-01

    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.

  9. 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.

  10. Californium Electrodepositions at Oak Ridge National Laboratory

    SciTech Connect

    Boll, Rose Ann

    2015-01-01

    Electrodepositions of californium isotopes were successfully performed at Oak Ridge National Laboratory (ORNL) during the past year involving two different types of deposition solutions, ammonium acetate (NH4C2H3O2) and isobutanol ((CH3)2CHCH2OH). A californium product that was decay enriched in 251Cf was recovered for use in super-heavy element (SHE) research. This neutron-rich isotope, 251Cf, provides target material for SHE research for the potential discovery of heavier isotopes of Z=118. The californium material was recovered from aged 252Cf neutron sources in storage at ORNL. These sources have decayed for over 30 years, thus providing material with a very high 251Cf-to-252Cf ratio. After the source capsules were opened, the californium was purified and then electrodeposited using the isobutanol method onto thin titanium foils for use in an accelerator at the Joint Institute for Nuclear Research in Dubna, Russia. Another deposition method, ammonium acetate, was used to produce a deposition containing 1.7 0.1 Ci of 252Cf onto a stainless steel substrate. This was the largest single electrodeposition of 252Cf ever prepared. The 252Cf material was initially purified using traditional ion exchange media, such as AG50-AHIB and AG50-HCl, and further purified using a TEVA-NH4SCN system to remove any lanthanides, resulting in the recovery of 3.6 0.1 mg of purified 252Cf. The ammonium acetate deposition was run with a current of 1.0 amp, resulting in a 91.5% deposition yield. Purification and handling of the highly radioactive californium material created additional challenges in the production of these sources.

  11. The ridges of Europa: Extensions of adjacent topography onto their flanks

    NASA Astrophysics Data System (ADS)

    Greenberg, Richard; Sak, Peter B.

    2014-03-01

    The surface of Europa displays numerous generations of intersecting arrays of linear ridges. At some locations along these ridges, older ridges on adjacent terrain appear to extend up the flank of a more recent ridge. It has thus been suggested that the ridges may have formed by upturning of that adjacent terrain. However, the newer ridges generally appear to be material deposited over the older terrain. Here we consider how the morphology of the overprinted topography may have been inherited by the more recent ridges. An analogous process occurs along some sediment-starved convergent plate boundaries on Earth, where the poorly consolidated material of a frontal prism of an overriding plate is pushed over preexisting ridges and seamounts on the downgoing plate. The overriding plate inherits the morphology of the downgoing plate even though the actual extension of that topography has been underthrust and buried. A well-studied example lies offshore of Costa Rica where the Caribbean plate overrides the Cocos plate. Experiments show other mechanisms as well: mass-wasting down a flank can result in extensions of adjacent ridges thanks to the geometry imposed by a constant angle of repose; in addition, more pronounced extensions of the older ridges result if the new ridge grows as it is bulldozed from behind (i.e., from the central groove of a double ridge on Europa). The shapes of the ridge extensions are distinctly different in these two cases. If tidal pumping extrudes material to the surface at the center of a double ridge, it might drive the latter mechanism. The ridge extensions observed on the flanks of more recent ridges may provide a crucial diagnostic of dominant ridge-building mechanisms when and if additional images are obtained at high resolution from future exploration. In additional to their morphology, the distribution of ridge extensions at only isolated locales may also provide constraints on ridge formation processes and their diversity.

  12. 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.

  13. Design demonstrations for category B tank systems at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1994-11-01

    This document presents design demonstrations conducted of liquid low-level waste (LLLW) storage tank systems located at the Oak Ridge National Laboratory (ORNL). Demonstration of the design of these tank systems has been stipulated by the Federal Facility Agreement (FFA) between the US Environmental Protection Agency (EPA)-Region IV; the Tennessee Department of Environment and Conservation (TDEC); and the DOE. The FFA establishes four categories of tanks. These are: Category A -- New or replacement tank systems with secondary containment; Category B -- Existing tank systems with secondary containment; Category C -- Existing tank systems without secondary containment; Category D -- Existing tank systems without secondary containment that are removed from service. This document provides a design demonstration of the secondary containment and ancillary equipment of 11 tank systems listed in the FFA as Category B. The design demonstration for each tank is presented.

  14. Resource Management plan for the Oak Ridge Reservation. Volume 28, Wetlands on the Oak Ridge Reservation

    SciTech Connect

    Cunningham, M.; Pounds, Larry

    1991-12-01

    A survey of wetlands on the Oak Ridge Reservation (ORR) was conducted in 1990. Wetlands occurring on ORR were identified using National Wetlands Inventory (NWI) maps and field surveys. More than 120 sites were visited and 90 wetlands were identified. Wetland types on ORR included emergent communities in shallow embayments on reservoirs, emergent and aquatic communities in ponds, forested wetland on low ground along major creeks, and wet meadows and marshes associated with streams and seeps. Vascular plant species occurring on sites visited were inventoried, and 57 species were added to the checklist of vascular plants on ORR. Three species listed as rare in Tennessee were discovered on ORR during the wetlands survey. The survey provided an intensive ground truth of the wetlands identified by NWI and offered an indication of wetlands that the NWI remote sensing techniques did not detect.

  15. Management of spent nuclear fuel on the Oak Ridge Reservation, Oak Ridge, Tennessee: Environmental assessment

    SciTech Connect

    1996-02-01

    On June 1, 1995, DOE issued a Record of Decision [60 Federal Register 28680] for the Department-wide management of spent nuclear fuel (SNF); regionalized storage of SNF by fuel type was selected as the preferred alternative. The proposed action evaluated in this environmental assessment is the management of SNF on the Oak Ridge Reservation (ORR) to implement this preferred alternative of regional storage. SNF would be retrieved from storage, transferred to a hot cell if segregation by fuel type and/or repackaging is required, loaded into casks, and shipped to off-site storage. The proposed action would also include construction and operation of a dry cask SNF storage facility on ORR, in case of inadequate SNF storage. Action is needed to enable DOE to continue operation of the High Flux Isotope Reactor, which generates SNF. This report addresses environmental impacts.

  16. Level 3 Baseline Risk Assessment for Building 3515 at Oak Ridge National Lab., Oak Ridge, TN

    SciTech Connect

    Wollert, D.A.; Cretella, F.M.; Golden, K.M.

    1995-08-01

    The baseline risk assessment for the Fission Product Pilot Plant (Building 3515) at the Oak Ridge National laboratory (ORNL) provides the Decontamination and Decommissioning (D&D) Program at ORNL and Building 3515 project managers with information concerning the results of the Level 3 baseline risk assessment performed for this building. The document was prepared under Work Breakdown Structure 1.4.12.6.2.01 (Activity Data Sheet 3701, Facilities D&D) and includes information on the potential long-term impacts to human health and the environment if no action is taken to remediate Building 3515. Information provided in this document forms the basis for the development of remedial alternatives and the no-action risk portion of the Engineering Evaluation/Cost Analysis report.

  17. Remedial investigation work plan for Chestnut Ridge Operable Unit 4 (Rogers Quarry/Lower McCoy Branch) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1993-09-01

    The Oak Ridge Y-12 Plant includes - 800 acres near the northeast comer of the reservation and adjacent to the city of Oak Ridge (Fig. 1-1). The plant is a manufacturing and developmental engineering facility that produced components for various nuclear weapons systems and provides engineering support to other Energy Systems facilities. More than 200 contaminated sites have been identified at the Y-12 Plant that resulted from past waste management practices. Many of the sites have operable units (OUs) based on priority and on investigative and remediation requirements. This Remedial Investigation RI work plan specifically addresses Chestnut Ridge OU 4. Chestnut Ridge OU 4 consists of Rogers Quarry and Lower McCoy Branch (MCB). Rogers Quarry, which is also known as Old Rogers Quarry or Bethel Valley Quarry was used for quarrying from the late 1940s or early 1950s until about 1960. Since that time, the quarry has been used for disposal of coal ash and materials from Y-12 production operations, including classified materials. Disposal of coal ash ended in July 1993. 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, support an Ecological Risk Assessment and a Human Health Risk Assessment, 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 OU 4. Potential migration pathways also will be investigated. Data collected during the RI will be used to evaluate the risk posed to human health and the environment by OU 4.

  18. Lomonosov Ridge as a Natural Component of Continental Margin

    NASA Astrophysics Data System (ADS)

    Poselov, V.; Kaminsky, V. D.; Butsenko, V. V.; Grikurov, G. E.

    2010-12-01

    In geodynamic context, Lomonosov Ridge is interpreted as a rifted passive margin framing the Eurasian oceanic basin. At the same time its near-Siberian segment is intimately associated with the Russian Arctic shelf, as evidenced by morphological data and the results of “Trans-Arctic 1992” and “Arctic-2007” geotransect studies. Coring and ACEX data demonstrated the presence in the uppermost geological section of the ridge of Late Cretaceous through Cenozoic sediments and Jurassic-Cretaceous sedimentary rocks; the latter may belong to deeper levels of sedimentary cover, or may represent the Mesozoic folded basement. Coarse bottom debris contains also the fragments of Riphean-Paleozoic rocks probably derived from the local bedrock source. Structure of sedimentary cover is imaged by continuous seismic observations from the shelf of East Siberian Sea along the length of Lomonosov Ridge to 85 N. In the upper part of the section there are two sedimentary sequences separated by a regional unconformity; their seismic velocities are 2.4-3.1 km/s in the upper sequence and 3.4-4.0 km/s in the lower one, and the total thickness reaches ~ 8 km in the deepest part of New Siberian Basin. Both these sequences and the unconformity are traced from Lomonosov Ridge into Amundsen Basin on seismic reflection sections obtained by drifting ice stations North Pole 2479 and 2480. The low-velocity sediments are underlain by a metasedimetary sequence with velocities decreasing from 4.7-4.9 km/s on the shelf to 4.4-4.9 km/s beneath continental slope and 4.2-4.8 km/s on Lomonosov Ridge. The thickness of metasedimentary sequence is about 7 km on the shelf, up to 3.5 km under continental slope, and strongly variable (1-5 km) on Lomonosov Ridge. The upper layer of consolidated crust is 8-9 km thick on the shelf with velocities 6.1-6.2 km/s; on Lomonosov Ridge both its thickness and velocities increase to 10 km and 6.0-6.4 km/s, respectively. In the lower crust the velocities do not exceed 6

  19. Ultra-slow-spreading - A New Class of Ocean Ridge

    NASA Astrophysics Data System (ADS)

    Dick, H. J.; Lin, J.; Michael, P. J.; Schouten, H.; Snow, J. E.

    2002-12-01

    Surveys of the the SW Indian and Gakkel Ridges show that ultra-slow spreading ridges are as different from slow spreading ridges as fast spreading ridges are from slow ? perhaps more so. At an effective spreading rate for mantle upwelling <~12 mm/yr (the full rate spreading component measured orthogonal to the ridge trend) there are dramatic changes. Magmatism becomes discontinuous, with mantle peridotite emplaced directly to the sea floor over large regions. Local magmatic centers are either ephemeral point source or occur at long-lived cross-axis volcanic highs. The latter are principally localized at bends in the ridge trend or at ridge transform intersections. Mantle peridotites emplaced to the sea floor range from harzburgite to lherzolite, despite low levels of melt production, suggesting that much of this variability predates the ridge melting event. While high-pressure vein assemblages are not present, evidence for late stage low-pressure melt impregnation is common, suggesting that the peridotites underwent partial fusion. This likely eliminated pre-existing vein assemblages. Ridge basalts differ from those at faster spreading ridges as they are generally enriched - possible evidence of a pre-existing vein assemblage. In magmatically active areas, rift axes are sub-orthogonal to the spreading direction with high-angle normal faults dominating the formation of axial and rift valley relief. In the absence of active magmatism, rift valley walls are more subdued, and follow the ridge trend. The walls of amagmatic spreading segments are often lower than those at magmatic segments and are either highly irregular or dominated by low-angle normal faults. The latter dip ~14°-18° and slope down from the crest of the rift valley wall to the floor of the axial trough on essentially a single fault surface. Despite this an orthogonal fabric defined by 50 to 200-m high-angle normal fault scarps, reflecting brittle plate extension, is ubiquitous. This is most easily

  20. Enabling Integration and Synthesis through the Ridge 2000 Data Portal

    NASA Astrophysics Data System (ADS)

    Ryan, W. B.; Ferrini, V.; Carbotte, S. M.; O'Hara, S.; Arko, R. A.; Bonczkowski, J.; Chan, S.

    2009-12-01

    Achieving an integrated, holistic understanding of global mid-ocean ridge (MOR) processes through the Ridge 2000 Program relies heavily on the sharing of data across disciplinary boundaries. Although most Ridge 2000 research has been focused on three Integrated Study Sites (ISSs), data from throughout the global mid-ocean ridge (MOR) system will also be important in the integration and synthesis phase of the program. The Ridge 2000 Data Portal (www.marine-geo.org/portals/ridge2000) is a resource established to facilitate the sharing, discovery, and integration of Ridge 2000-relevant data by providing data documentation and access. The Data Portal includes an inventory of field programs and activities, raw and derived data files, and access to publications and remote data sets in specialized data systems (e.g. PetDB, www.petdb.org; GenBank, www.ncbi.nlm.nih.gov; NGDC, www.ngdc.noaa.gov). Access to the R2K database is provided through several pathways, including a web-based search interface (www.marine-geo.org/tools/search) that now includes basic and advanced search functionality. New versions of our data exploration and visualization tool GeoMapApp (www.geomapapp.org) includes a newly designed menu system with cascading and tear-off menus, a new Layer Manager that lists selected layers and enables re-ordering and rendering with variable transparency, a Go To option that allows direct zooming to areas of interest, and an Add Image Overlay option for importing georeferenced images. New data sets are continually added to both GeoMapApp and Virtual Ocean (www.virtualocean.org), a 3D virtual globe with GeoMapApp functionality. Several Ridge 2000 data sets are also bundled for viewing in Google Earth (www.marine-geo.org/tools/kmls.php). This poster will highlight new functionality and data sets relevant to Ridge 2000 Integration and Synthesis, and will provide comparisons of several data sets that exist for each ISS.

  1. The timescales of magma evolution at mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Brandl, Philipp A.; Regelous, Marcel; Beier, Christoph; O'Neill, Hugh St. C.; Nebel, Oliver; Haase, Karsten M.

    2016-01-01

    Oceanic crust is continuously created at mid-ocean ridges by decompression melting of the upper mantle as it upwells due to plate separation. Decades of research on active spreading ridges have led to a growing understanding of the complex magmatic, tectonic and hydrothermal processes linked to the formation of new oceanic igneous crust. However, less is known about the timescales of magmatic processes at mid-ocean ridges, including melting in and melt extraction from the mantle, fractional crystallisation, crustal assimilation and/or magma mixing. In this paper, we review the timescales of magmatic processes by integrating radiometric dating, chemical and petrological observations of mid-ocean ridge basalts (MORBs) and geophysical models. These different lines of evidence suggest that melt extraction and migration, and crystallisation and mixing processes occur over timescales of 1 to 10,000 a. High-resolution geochemical stratigraphic profiles of the oceanic crust using drill-core samples further show that at fast-spreading ridges, adjacent flow units may differ in age by only a few 100 a. We use existing chemical data and new major- and trace-element analyses of fresh MORB glasses from drill-cores in ancient Atlantic and Pacific crust, together with model stratigraphic ages to investigate how lava chemistry changes over 10 to 100 ka periods, the timescale of crustal accretion at spreading ridges which is recorded in the basalt stratigraphy in drilled sections through the oceanic crust. We show that drilled MORBs have compositions that are similar to those of young MORB glasses dredged from active spreading ridges (lavas that will eventually be preserved in the lowermost part of the extrusive section covered by younger flows), showing that the dredged samples are indeed representative of the bulk oceanic crust. Model stratigraphic ages calculated for individual flows in boreholes, together with the geochemical stratigraphy of the drilled sections, show that at

  2. Geology of Smooth Ridge: MARS-IODP Cabled Observatory Site

    NASA Astrophysics Data System (ADS)

    Jordahl, K. A.; Paull, C. K.; Ussler, W.; Aiello, I. W.; Mitts, P.; Greene, H. G.; Gibbs, S.

    2004-12-01

    We document the geologic environment of Smooth Ridge, off shore Central California, where the deep-water node associated with the MARS (Monterey Accelerated Research Site) scientific research cable is to be deployed. The MARS cable will provide internet connections and electric power at a node in 890 m of water in support of scientific observatory development and experiments. IODP boreholes are proposed which will be connected to the MARS cable. The deeply incised channels of Monterey and Soquel Canyons flank Smooth Ridge to the SW and NE and the San Gregorio faults marks its NW and upslope boundary. However, the top of Smooth Ridge, as its name implies, only has subdued bathymetric features. These include a subtle downslope channel and one distinct slump scar. A patch of acoustically reflective seafloor on the west side of the ridge, over 5 km from the MARS site, is associated with the only known large-scale biological community on the crest of Smooth Ridge. A reflection seismic survey conducted in 2003 with a high-resolution electrical sparker source reveals the stratigraphy of the Smooth Ridge in unprecedented detail. In conjunction with previously collected widely-spaced multichannnel seismic data, observations and samples obtained using remotely-operated vehicle (ROV) dives, and piston cores, this new survey reveals the erosional and depositional history of Smooth Ridge. The continuity of seismic reflections indicates nearly undisturbed deposition occurred until at least the mid-Miocene. Since that time, and especially since the upper Pliocene, the record is marked by unconformities and infill due to shifting channels, large slumps and landslides, and sediment waves. Several crossing seismic lines provide a quasi-three-dimensional view of a distinct slump scar's structure, and reveal a history of multiple headwall failures. Other subsurface structures, including a much larger, and older, slump feature, have no bathymetric expression at all. 14C dated piston

  3. Base cation controlled recovery from acidification in streams in the Ridge/Blue Ridge provinces

    NASA Astrophysics Data System (ADS)

    Robison, A.; Scanlon, T. M.; Cosby, B. J.; Webb, R.; Galloway, J. N.

    2012-12-01

    Widespread recovery of surface waters from acidification has been documented throughout the U.S. and Europe over recent decades with a notable exception being the Ridge/Blue Ridge province of the central Appalachians of the U.S. In this region, a decrease in sulfate deposition has not led to a similar decrease in surface water concentrations of this acid anion. Sixty four streams in western Virginia were sampled on a quarterly basis from 1987 to 2010 and were analyzed for various chemical and physical properties. We report here that while acidification continues for most systems, recovery, in terms of increasing acid neutralizing capacity (ANC), has begun to occur in the region on a limited basis. Over the timeframe of study, 33% of the streams demonstrated a positive trend in ANC. The status of watersheds with respect to acidification is controlled primarily by the availability of base cations derived from the underlying bedrock. Recovery was associated almost exclusively by watersheds underlain by relatively base-rich mafic and felsic bedrock, while continued acidification was dominated by sites with relatively base-poor siliciclastic and argillaceous bedrock. Further influencing recovery is the region's high soil sulfate adsorption capacity, a result of older, more highly weathered soils that were not impacted during the most recent glacial maxima. This factor is the main cause of the delayed response of watersheds to decreased acidic deposition. However, a mass balance analysis of sulfate at the base-poor White Oak Run watershed reveals export may soon surpass storage for the first time in the nearly three decades of continuous monitoring. Therefore, recovery from acidification may be near for the region's more ubiquitous base-poor watersheds, as steam sulfate concentrations are predicted to finally decrease. Our findings show a positive, albeit limited step in the recovery of this region from acidification and suggest that more widespread recovery could being

  4. Survey of protected vascular plants on the Oak Ridge Reservation, Oak Ridge, Tennessee

    SciTech Connect

    Awl, D.J.; Pounds, L.R.; Rosensteel, B.A.; King, A.L.; Hamlett, P.A.

    1996-06-01

    Vascular plant surveys were initiated during fiscal year 1992 by the environmentally sensitive areas program to determine the baseline condition of threatened and endangered (T&E) vascular plant species on the Oak Ridge Reservation (ORR). T&E species receive protection under federal and state regulations. In addition, the National Environmental Policy Act (NEPA) requires that federally-funded projects avoid or mitigate impacts to listed species. T&E plant species found on or near the U.S. Department of Energy`s (DOE) Oak Ridge Reservation (ORR) are identified. Twenty-eight species identified on the ORR are listed by the Tennessee Department of Environment and Conservation as either endangered, threatened, or of special concern. Four of these have been under review by the U.S. Fish and Wildlife Service for possible listing (listed in the formerly-used C2 candidate category). Additional species listed by the state occur near and may be present on the ORR. A range of habitats support the rare taxa on the ORR: river bluffs, sinkholes, calcareous barrens, wetlands, utility corridors, and forests. The list of T&E plant species and their locations on the ORR should be considered provisional because the entire ORR has not been surveyed, and state and federal status of all species continues to be updated. The purpose of this document is to present information on the listed T&E plant species currently known to occur on the ORR as well as listed species potentially occurring on the ORR based on geographic range and habitat availability. For the purpose of this report, {open_quotes}T&E species{close_quotes} include all federal- and state-listed species, including candidates for listing, and species of special concern. Consideration of T&E plant habitats is an important component of resource management and land-use planning; protection of rare species in their natural habitat is the best method of ensuring their long-term survival.

  5. Evidence of 60 meter deep Arctic pressure-ridge keels

    SciTech Connect

    Reimnitz, E.; Barnes, P.W.; Phillips, R.L.

    1985-11-01

    Numerous efforts have been made during the last two decades to determine the ice thickness distribution in the Arctic Ocean and in particular to learn the keel depth of the largest modern pressure ridges. With the discovery of oil and gas in the arctic offshore and the trend to extend exploration into deeper water and increasing distance from shore, knowledge of the maximum ice thickness in the continental shelf is becoming increasingly important. Various approaches have been used to directly obtain keel depth data in the Arctic, but no satisfactory technique for water depths of less than 100 meters exists. For continental shelves, virtually all public data on ridge keel configuration stems from spot measurements made with horizontally held sonar transducers lowered through the ice adjacent to ridges, and from cores of ridges. Because these techniques are time-consuming, the depths of only a few ridge keels have been determined by such methods. Fixed upward-looking sonar devices have been used with limited success in several applications to record under-ice relief and movement, but any data so obtained is not public. This report is an attempt to interpret the age of deepwater gouges seen on the Alaskan Arctic shelf.

  6. The negative gravity field over the 85 deg E ridge

    NASA Technical Reports Server (NTRS)

    Liu, C.-S.; Curray, J. R.; Sandwell, D. T.

    1982-01-01

    Two north-south ridges in the basement topography of the Bay of Bengal may be observed on an isopach map at 85 and at 90 deg E. Free-air gravity anomaly profiles across the region show a strong gravity low (about -60 mGal) over the 85 deg E ridge, and a gravity high over the other. Using a simple two-stage loading model, the negative gravity anomaly over the 85 deg E ridge is explained as a direct consequence of sediment loading, and the flexural rigidity of the lithosphere when the ridge was formed is estimated to have been about 180 times less than the flexural rigidity during the sediment loading. An approximate relationship between flexural rigidity and crustal age shows that the 85 deg E ridge was formed on relatively young lithosphere, 5-15 million years old, and that it was buried when the lithosphere was 40-80 million years old. The alteration of the gravity field by a thick layer of sediments may occur in other large sedimentary basins or along continental margins.

  7. Ancient, highly heterogeneous mantle beneath Gakkel ridge, Arctic Ocean.

    PubMed

    Liu, Chuan-Zhou; Snow, Jonathan E; Hellebrand, Eric; Brügmann, Gerhard; von der Handt, Anette; Büchl, Anette; Hofmann, Albrecht W

    2008-03-20

    The Earth's mantle beneath ocean ridges is widely thought to be depleted by previous melt extraction, but well homogenized by convective stirring. This inference of homogeneity has been complicated by the occurrence of portions enriched in incompatible elements. Here we show that some refractory abyssal peridotites from the ultraslow-spreading Gakkel ridge (Arctic Ocean) have very depleted 187Os/188Os ratios with model ages up to 2 billion years, implying the long-term preservation of refractory domains in the asthenospheric mantle rather than their erasure by mantle convection. The refractory domains would not be sampled by mid-ocean-ridge basalts because they contribute little to the genesis of magmas. We thus suggest that the upwelling mantle beneath mid-ocean ridges is highly heterogeneous, which makes it difficult to constrain its composition by mid-ocean-ridge basalts alone. Furthermore, the existence of ancient domains in oceanic mantle suggests that using osmium model ages to constrain the evolution of continental lithosphere should be approached with caution.

  8. The Sagatu Ridge dike swarm, Ethiopian rift margin. [tectonic evolution

    NASA Technical Reports Server (NTRS)

    Mohr, P. A.; Potter, E. C.

    1976-01-01

    A swarm of dikes forms the core of the Sagatu Ridge, a 70-km-long topographic feature elevated to more than 4000 m above sea level and 1500 m above the level of the Eastern (Somalian) plateau. The ridge trends NNE and lies about 50 km east of the northeasterly trending rift-valley margin. Intrusion of the dikes and buildup of the flood-lava pile, largely hawaiitic but with trachyte preponderant in the final stages, occurred during the late Pliocene-early Pleistocene and may have been contemporaneous with downwarping of the protorift trough to the west. The ensuing faulting that formed the present rift margin, however, bypassed the ridge. The peculiar situation and orientation of the Sagatu Ridge, and its temporary existence as a line of crustal extension and voluminous magmatism, are considered related to a powerful structural control by a major line of Precambrian crustal weakness, well exposed further south. Transverse rift structures of unknown type appear to have limited the development of the ridge to the north and south.

  9. Structural style and petroleum prospects of Tonga Ridge

    SciTech Connect

    Pflueger, J.; Havard, K.; Gatliff, R.; Helu, B.

    1989-03-01

    Recent reprocessing of seismic data from the Tonga Ridge has provided a clearer picture of the tectonic style of a forearc basin. Sediments along the ridge achieve a maximum thickness of more than 4000 m. Many faults have been observed, almost all of which are normal. The presence of scarps on the sea floor show that a significant percentage of the faults are active today. Although seismic transverses are not spaced closely enough to allow unambiguous definition of fault orientations, they believe that most of the tensional faults are parallel to the ridge axis. A second set of near-vertical faults with apparent transcurrent movement exists at a high angle to the ridge axis. Bathymetry has played a major role in defining the strikes of the second set of faults. The tensional failures are due to the flexing of the ridge as the leading edge of the Indo-Australian plate is pulled down and under by frictional attachment to the subducting Pacific plate. The development of major fault blocks is related to the subduction of Pacific plate seamounts. Fault-bounded closures and Eocene to Miocene reefs would form excellent traps for hydrocarbons. Oil seeps of biodegaded but thermally mature crude oil on the island of Tongatanu encouraged the drilling of five exploratory test wells, but the source rock feeding the seeps was not discovered. Burial history and geothermal modeling indicate that mature source rocks could occur deeper than depths penetrated by the test wells.

  10. The Mozambique Ridge: a document of massive multistage magmatism

    NASA Astrophysics Data System (ADS)

    Fischer, Maximilian D.; Uenzelmann-Neben, Gabriele; Jacques, Guillaume; Werner, Reinhard

    2017-01-01

    The Mozambique Ridge, a prominent basement high in the southwestern Indian Ocean, consists of four major geomorphological segments associated with numerous phases of volcanic activity in the Lower Cretaceous. The nature and origin of the Mozambique Ridge have been intensely debated with one hypothesis suggesting a Large Igneous Province origin. High-resolution seismic reflection data reveal a large number of extrusion centres with a random distribution throughout the southern Mozambique Ridge and the nearby Transkei Rise. Intrabasement reflections emerge from the extrusion centres and are interpreted to represent massive lava flow sequences. Such lava flow sequences are characteristic of eruptions leading to the formation of continental and oceanic flood basalt provinces, hence supporting a Large Igneous Province origin of the Mozambique Ridge. We observe evidence for widespread post-sedimentary magmatic activity that we correlate with a southward propagation of the East African Rift System. Based on our volumetric analysis of the southern Mozambique Ridge we infer a rapid sequential emplacement between ˜131 and ˜125 Ma, which is similar to the short formation periods of other Large Igneous Provinces like the Agulhas Plateau.

  11. Oak Ridge Y-12 Plant groundwater protection program management plan

    SciTech Connect

    1996-06-01

    The Oak Ridge Y- 1 2 Plant (Y-12 Plant) is owned by the United States Department of Energy (DOE) and managed by Lockheed Martin Energy Systems, Inc. (Energy Systems) under contract No. DE-AC05-84OR21400. The Y-12 Plant Groundwater Protection Program (GWPP), which was initiated in 1975, provides for the protection of groundwater resources consistent with Federal, State, and local regulations, and in accordance with DOE orders and Energy Systems policies and procedures. The Y-12 Plant is located in Anderson County, Tennessee, and is within the corporate limits of the City of Oak Ridge. The Y-12 Plant is one of three major DOE complexes that comprise the 37,000-acre Oak Ridge Reservation (ORR) located in Anderson and Roane counties. The Y-12 Plant is located in Bear Creek Valley at an elevation of about 950 feet (ft) above sea level. Bear Creek Valley is bounded on the northwest and southeast, and is isolated from populated areas of Oak Ridge, by parallel ridges that rise about 300 ft above the valley floor. The Y-12 Plant and its fenced buffer area are about 0.6 mile wide by 3.2 miles long and cover approximately 4,900 acres. The main industrialized section encompasses approximately 800 acres.

  12. Basalts dredged from the Amirante ridge, western Indian ocean

    USGS Publications Warehouse

    Fisher, R.L.; Engel, C.G.; Hilde, T.W.C.

    1968-01-01

    Oceanic tholeiitic basalts were dredged from 2500 to 3000 m depth on each flank of the Amirante Ridge, 1200 km southeast of Somalia in the western Indian Ocean, by R.V. Argo in 1964. One sample, probably shed from a flow or dike in basement beneath the coralline cap, gave a wholerock KAr age of 82??16??106 years. The age is similar to those reported by others for agglomerate from Providence Reef, nearer Madagascar, and for gabbro from Chain Ridge, the southwest member of Owen Fracture Zone, nearer the Somali coast. The Amirante Cretaceous-Early Tertiary occurrence lies between the "continental" 650 ?? 106 years granites of Seychelles Archipelago and the large Precambrian "continental" block of Madagascar. Trends of major structures and distribution of the related topographic and magnetic-anomaly lineations in 7-8 ?? 106 km2of the surrounding Indian Ocean suggest that in addition to spreading of the seafloor from the seismically-active Mid-Indian Ocean Ridge-Carlsberg Ridge complex there has been, since mid-Mesozoic time, distributed left-lateral shear along 52??-54??E that has moved Madagascar at least 700 km south relative to Seychelles Bank. Measurements by other indicate the absolute movement of Madagascar has been southward as well. The emplacement of oceanic tholeiitic basalts at shallow depth, the development of volcanic topography between the sedimented Somali and Mascarene basins, and the existence of the faulted Amirante Trench and Ridge are consequences of the displacement. ?? 1968.

  13. Where are the undiscovered hydrothermal vents on oceanic spreading ridges?

    NASA Astrophysics Data System (ADS)

    Beaulieu, Stace E.; Baker, Edward T.; German, Christopher R.

    2015-11-01

    In nearly four decades since the discovery of deep-sea vents, one-third of the length of global oceanic spreading ridges has been surveyed for hydrothermal activity. Active submarine vent fields are now known along the boundaries of 46 out of 52 recognized tectonic plates. Hydrothermal survey efforts over the most recent decade were sparked by national and commercial interests in the mineral resource potential of seafloor hydrothermal deposits, as well as by academic research. Here we incorporate recent data for back-arc spreading centers and ultraslow- and slow-spreading mid-ocean ridges (MORs) to revise a linear equation relating the frequency of vent fields along oceanic spreading ridges to spreading rate. We apply this equation globally to predict a total number of vent fields on spreading ridges, which suggests that ~900 vent fields remain to be discovered. Almost half of these undiscovered vent fields (comparable to the total of all vent fields discovered during 35 years of research) are likely to occur at MORs with full spreading rates less than 60 mm/yr. We then apply the equation regionally to predict where these hydrothermal vents may be discovered with respect to plate boundaries and national jurisdiction, with the majority expected to occur outside of states' exclusive economic zones. We hope that these predictions will prove useful to the community in the future, in helping to shape continuing ridge-crest exploration.

  14. Shallow subduction, ridge subduction, and the evolution of continental lithosphere

    SciTech Connect

    Helmstaedt, H.; Dixon, J.M.; Farrar, E.; Carmichael, D.M.

    1985-01-01

    Subduction of oceanic lithosphere beneath continental crust at a shallow angle has occurred throughout the Phanerozoic Eon. Ridge subduction often follows shallow subduction and causes bimodal volcanism and crustal rifting, forming back-arc basins. Recent models for Archean plate tectonics propose very fast rates of spreading (400-800 km/Ma) and convergence, and sinking rates comparable to or slower (<10 km/Ma) than those of today. As faster convergence and slower sinking correspond to subduction at shallower angles, shallow subduction and ridge subduction must have been ubiquitous during the Archean permobile regime. This is compatible with a back-arc-basin origin for Archean greenstone belts. The common coexistence of tholeiitic and calc-alkaline igneous rocks in Archean greenstone belts, also implies ridge subduction. The authors envisage a transition, between 2.4 and 1.8 Ga., from a regime dominated by shallow subduction and repeated ridge subduction to one of normal plate tectonics with steeper subduction. Spreading rates decreased; continental plates became larger and stable shelves could develop at trailing margins. Shallow subduction became the exception, restricted to episodes of abnormally fast convergence; nevertheless, the long span of post-Archean time makes it unlikely that any part of the continental crust has escaped shallow subduction and ridge subduction. These processes recycle much volatile-rich oceanic crust into the sub-continental upper mantle, thereby underplating the crust, effecting upper-mantle metasomatism and affecting intraplate magmatism.

  15. Topography and tectonics of mid-oceanic ridge axes

    NASA Technical Reports Server (NTRS)

    Sleep, N. H.; Rosendahl, B. R.

    1979-01-01

    Numerical fluid dynamic models of mid-oceanic ridge axes were constructed using distributions of material properties constrained by seismic studies and thermal calculations. The calculations indicate that spreading is passive except for forces caused by density differences due to thermal expansion and partial melt. Except for geometric differences due to temperature distribution, one set of mechanical properties can adequately explain central rifts of slow ridges and central peaks of fast ridges. Viscous head loss in the upwelling material dominates at low spreading rates where material ascends through a narrow conduit. Thermal expansion and partial melting dominate at high spreading rates where a wide low viscosity crustal magma chamber is present. The preferred rheology is 10 to the 20th poise for the upwelling lithosphere; less than 5 x 10 to the 17th for the crustal magma chamber and axial intrusion zone at fast ridges, and a yield stress of 200 bars for the lithosphere. The calculation correctly predicts the existence of central peaks at 'hot-spot' ridges, where seismic evidence indicates a large magma chamber.

  16. Dermal digital ridge density of a penal population: Analysis of association and individualization.

    PubMed

    Kaur, Maninder; Sharma, Krishan

    2016-11-01

    The present study is an attempt to analyze an association between dermal digital ridge density and explosive personality based on the study of 100 male prisoners and 50 controls. The control group had higher ridge density than the prisoners. Bilateral differences revealed higher ridge density on left hand than right hand in both the groups, but differences between two groups for directional asymmetry were not significant. Surface area is not correlated with ridge density in all the digits. About 50% of the variation in ridge density may be explained by a single factor which in all probability is the genetic component of variation. Ridge density cannot be used as a marker for assessing individual's height. Individuals having ridge density less than 12 ridges and higher than 15 ridges, i.e. placed on the two extremes were more likely than not to have more explosive personality.

  17. Effect of longitudinal ridges on the hydrodynamic performance of a leatherback turtle model

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    Leatherback sea turtles (Dermochelys coriacea) known as the fastest swimmer and the deepest diver among marine turtles have five longitudinal ridges on their carapace, and these ridges are the most remarkable morphological features distinguished from other marine turtles. To investigate the effect of these ridges on the hydrodynamic performance of the leatherback turtle, we model a carapace with and without ridges using a stuffed leatherback turtle in the National Science Museum, Korea. We measure the drag and lift forces on the ridged model in the ranges of real leatherback turtles' Reynolds number (Re) and angle of attack (α), and compare them with those of non-ridged model. At α < 6°, longitudinal ridges decrease drag on the ridged model by up to 32% compared to non-ridged model. On the other hand, at α > 6°, the drag and lift coefficients of the ridged model are higher than those of the non-ridged model, and the lift-to-drag ratio of the ridged model is higher by about 7% than that of the non-ridged model. We also measure the velocity field around both models using a particle image velocimetry and explain the hydrodynamic role of ridges in relation to diving behaviors of leatherback sea turtles. Supported by the NRF Program (2011-0028032).

  18. Sea level forcing of mid-ocean ridge magmatism on Milankovitch timescales

    NASA Astrophysics Data System (ADS)

    Lund, D.; Asimow, P.

    2008-12-01

    delivery from 30 kyr BP to 20 kyr BP, driven by a 50 m decrease in sea level. Melt delivery decreased more than 50% from the Last Glacial Maximum to 5 kyr BP, driven by the ~120 m rise in sea level during the deglaciation. Our results suggest that modest changes in hydrostatic pressure driven by ice sheet growth and decay yield substantial alterations in magma flux at mid-ocean ridges relative to steady state conditions. These simulations raise the possibility that mantle melting may act as a negative feedback on ice sheet size by modulating deep ocean temperature. We estimate that enhanced melt production during sea level low-stands increases deep ocean temperature by order 0.1 °C. We speculate this modest warming may contribute to deglaciations by reducing sea-ice extent in the Southern Ocean, which may in turn promote ventilation of the abyssal ocean and the release of sequestered carbon dioxide to the atmosphere. References: Asimow, P.D., et al., 2004. G-cubed 5(1): 10.1029/2003GC000568. Ghiorso, M.S., et al., 2002. G-cubed 3(5): 10.1029/2001GC000217. Jull, M., and McKenzie, D., 1996. JGR 101(B10): 21815-21828. Maclennan, J., et al., 2002. G-cubed 3(11): 10.1029/2001GC000282 Workman, R.K. and Hart, S.R., 2005. EPSL 231(1-2): 53-72.

  19. High-power 1300-nm Fabry-Perot and DFB ridge-waveguide lasers

    NASA Astrophysics Data System (ADS)

    Garbuzov, Dmitri Z.; Maiorov, Mikhail A.; Menna, Raymond J.; Komissarov, Anatoly V.; Khalfin, V.; Kudryashov, Igor V.; Lunev, Alexander V.; DiMarco, Louis A.; Connolly, John C.

    2002-05-01

    In this paper we summarize the results on the development of high power 1300 nm ridge waveguide Fabry-Perot and distributed-feedback (DFB) lasers. Improved performance of MOCVD grown InGaAsP/InP laser structures and optimization of the ridge waveguide design allowed us to achieve more than 800 mW output power from 1300 nm single mode Fabry-Perot lasers. Despite the fact that the beam aspect ratio for ridge lasers (30 degree(s) x 12 degree(s)) is higher than that for buried devices, our modeling and experiments demonstrated that the fiber coupling efficiency of about 75-80% could be routinely achieved using a lensed fiber or a simple lens pair. Fiber power of higher than 600 mW was displayed. Utilizing similar epitaxial structures and device geometry, the 1300 nm DFB lasers with output power of 500 mW have been fabricated. Analysis of the laser spectral characteristics shows that the high power DFB lasers can be separated into several groups. The single frequency spectral behavior was exhibited by about 20% of all studied DFB lasers. For these lasers, side-mode suppression increases from 45 dB at low current up to 60 dB at maximum current. About 30% of DFB lasers, at all driving currents, demonstrate multi-frequency spectra consisting of 4-8 longitudinal modes with mode spacing larger than that for Fabry-Perot lasers of the same cavity length. Both single frequency and multi frequency DFB lasers exhibit weak wavelength-temperature dependence and very low relative intensity noise (RIN) values. Fabry-Perot and both types of DFB lasers can be used as pump sources for Raman amplifiers operating in the 1300 nm wavelength range where the use of EDFA is not feasible. In addition, the single-mode 1300 nm DFB lasers operating in the 500 mW power range are very attractive for new generation of the cable television transmission and local communication systems.

  20. Ridge-Runnel and Swash Dynamics Field Experiment on a Steep Meso-Tidal Beach

    NASA Astrophysics Data System (ADS)

    Figlus, J.; Chardon-Maldonado, P.; Puleo, J. A.

    2014-12-01

    Ridge-runnel (RR) systems are morphological features that may form in the intermittently wet and dry zone of the beach immediately after storm events. Their onshore migration provides a natural way of recovery for an eroded beach but the detailed swash interactions and complex feedback mechanisms between wave dynamics, sediment transport and profile evolution are not well understood and challenging to measure in-situ. During a storm, elevated water levels and large waves can significantly erode the beach profile in a matter of hours through offshore-directed sediment transport. The beach recovery process, on the other hand, occurs over a much longer time period during less intense wave conditions. In the beginning of this 3-week field campaign at South Bethany Beach, Delaware, a Nor'easter, eroded significant portions of this steep, meso-tidal beach and formed a pronounced RR system which then evolved during the less energetic conditions after the storm. An extensive cross-shore array of sensors was installed immediately after the storm measuring near-bed velocity profiles (5 Nortek Vectrino Profilers) and horizontal velocities (6 Sontec Electromagnetic Current Meters; 1 side-looking Nortek Vectrino) suspended sediment concentrations (10 Optical Backscatter Sensors OBS-3+), and pressure fluctuations (7 GE Druck pressure transducers) in the swash zone. Dense topography surveys of the RR system were conducted twice a day during low tide conditions with a Leica RTK GPS rover system. In addition, sediment grab samples along the entire RR cross-section were collected daily. An offshore ADCP with surface wave tracking capability (Nortek 2MHz AWAC AST) measured directional wave spectra and current profiles at a water depth of approximately 6m. The RR system showed rapid onshore migration over the two tide cycles immediately after the storm, followed by a period of vertical ridge accretion of up to 3 ft at certain locations. A first look at the collected data and analysis

  1. Oak Ridge National Laboratory Wireless Charging of Electric Vehicles - CRADA Report

    SciTech Connect

    Onar, Omer C.; Campbell, Steven L.; Seiber, Larry Eugene; White, Cliff P.; Chinthavali, Madhu Sudhan; Tang, Lixin; Chambon, Paul H.; Ozpineci, Burak; Smith, David E.

    2016-06-20

    Wireless power transfer (WPT) is a paradigm shift in electric-vehicle (EV) charging that offers the consumer an autonomous, safe, and convenient option to conductive charging and its attendant need for cables. With WPT, charging process can be fully automated due to the vehicle and grid side radio communication systems, and is non-contacting; therefore issues with leakage currents, ground faults, and touch potentials do not exist. It also eliminates the need for touching the heavy, bulky, dirty cables and plugs. It eliminates the fear of forgetting to plug-in and running out of charge the following day and eliminates the tripping hazards in public parking lots and in highly populated areas such as shopping malls, recreational areas, parking buildings, etc. Furthermore, the high-frequency magnetic fields employed in power transfer across a large air gap are focused and shielded, so that fringe fields (i.e., magnetic leakage/stray fields) attenuate rapidly over a transition region to levels well below limits set by international standards for the public zone (which starts at the perimeter of the vehicle and includes the passenger cabin). Oak Ridge National Laboratory s approach to WPT charging places strong emphasis on radio communications in the power regulation feedback channel augmented with software control algorithms. The over-arching goal for WPT is minimization of vehicle on-board complexity by keeping the secondary side content confined to coil tuning, rectification, filtering, and interfacing to the regenerative energy-storage system (RESS). This report summarizes the CRADA work between the Oak Ridge National Laboratory and the Toyota Research Institute of North America, Toyota Motor Engineering and Manufacturing North America (TEMA) on the wireless charging of electric vehicles which was funded by Department of Energy under DE-FOA-000667. In this project, ORNL is the lead agency and Toyota TEMA is one of the major partners. Over the course of the project

  2. Self-controlled feedback: does it enhance learning because performers get feedback when they need it?

    PubMed

    Chiviacowsky, Suzete; Wulf, Gabriele

    2002-12-01

    This paper examines whether self-controlled feedback schedules enhance learning, because they are more tailored to the performers' needs than externally controlled feedback schedules. Participants practiced a sequential timing task. One group of learners (self-control) was provided with feedback whenever they requested it, whereas another group (yoked) had no influence on the feedback schedule. The self-control group showed learning benefits on a delayed transfer test. Questionnaire results revealed that self-control learners asked for feedback primarily after good trials and yoked learners preferred to receive feedback after good trials. Analyses demonstrated that errors were lower on feedback than no-feedback trials for the self-control group but not for the yoked group. Thus, self-control participants appeared to use a strategy for requesting feedback. This might explain learning advantages of self-controlled practice.

  3. Geochemical constraints on the formation of near-ridge Vance seamount chain at the Juan de Fuca Ridge (Invited)

    NASA Astrophysics Data System (ADS)

    Walters, R. L.; Hann, N.; Perfit, M. R.

    2013-12-01

    Observations and sampling of off-axis lava flows and near-ridge seamounts, coupled with the recent discovery of large melt bodies away from ridge axes, attest to the significance of off-axis magmatic phenomena for the formation of the oceanic lithosphere at mid-ocean ridges (MORs). One of the most crucial unsolved questions of oceanic volcanism surrounds the physical mantle processes that cause the initial formation of near-ridge seamounts and sustain volcanism over several million years to produce seamount chains. The Vance Seamounts are just one example of a series of near-ridge seamount chains on the Pacific Plate. The chain comprises six submarine mountains that sit more than 1km above the surrounding oceanic crust just west of the Vance segment of the Juan de Fuca Ridge (JdFR). Dive observations indicate that the seamount chain formed sequentially with the oldest seamount furthest from the ridge axis. The geochemical characteristics of the oldest seamount suggest that the initiation of seamount volcanism was associated with a localized chemical (× thermal) heterogeneity in the mantle. Trace element and isotopic signatures suggest that the chemical heterogeneity was progressively depleted as subsequent seamounts were formed. Central seamount lavas have N-MORB compositions with trace element and isotopic ratios that are significantly more depleted than N-MORB lavas erupted at the JdFR axis. Depletion in the most incompatible elements is so severe for the central seamounts that no physically realistic forward geochemical models involving average depleted MORB mantle can reproduce potential parental melt compositions. The lava compositions from seamounts closest to the ridge reverse the trend in trace element depletion becoming more similar to N-MORB erupted at the current axis. We suggest that excess melt is generated off-axis due to the impingement of a discrete chemical heterogeneity that is more fusible than the DMM matrix. A variety of 2D model ridge

  4. Hybrid on-axis plus ridge-perpendicular circulation reconciles hydrothermal flow observations at fast spreading ridges

    NASA Astrophysics Data System (ADS)

    Hasenclever, J.; Theissen-Krah, S.; Rupke, L.; Morgan, J.; Iyer, K. H.; Petersen, S.; Devey, C. W.

    2013-12-01

    We present crustal-scale 3D numerical calculations of hydrothermal fluid flow at fast spreading ridges. The model domain covers 5 km along-axis, 20 km across-axis and extends down to Moho depth. We observe that a complex hydrothermal system develops that extends over the entire crustal thickness and forms a series of on-axis vent fields with an average along-ridge spacing of 500-1000m. This hydrothermal system comprises two distinct flow components: (1) An on-axis circulation above the melt lens with recharging flow surrounding the hot up-flow zones. (2) A ridge-perpendicular circulation with recharge areas located kilometers away from the ridge. Here fluids penetrate the crust down to Moho depth and travel at temperatures of 400-600°C towards the ridge where they merge with the on-axis circulation in a reaction zone above the axial melt lens. Fluids released at the seafloor are a mixture of both components, with an average ratio between proximately- and distally-sourced fluids of about 2:1. This hybrid hydrothermal system reconciles previously incompatible observations that support either on-axis or ridge-perpendicular circulation patterns. The potential co-existence of two interacting hydrothermal circulations at fast spreading ridges is of importance for the interpretation of chemical signatures at hydrothermal vents and the quantification of the mass and energy exchange between ocean and solid earth: (1) A vertically and laterally extended ridge-perpendicular circulation will expose a much larger volume of oceanic crust to high-temperature hydrothermal alteration. Especially the lower crust would also be exposed to significant hydrothermal fluid flow and thus geochemical mining. (2) Fluids that migrate ridge-perpendicular and undergo phase separation at depth are likely to separate gravitationally from the denser and highly saline brine phase. Only the vapor-like phase may migrate up-slope towards the top of the melt lens, where these fluids would provide a

  5. Measuring Feedback in Nearby AGN

    NASA Astrophysics Data System (ADS)

    Crenshaw, D. M.; Fischer, T. C.; Kraemer, S. B.; Schmitt, H. R.; Turner, T. J.

    2012-08-01

    We investigate the impact of feedback from outflowing UV and X-ray absorbers in nearby (z < 0.04) AGN. From studies of the kinematics, physical conditions, and variability of the absorbers in the literature, we calculate the possible ranges in total mass outflow rate (Ṁout) and kinetic luminosity (LK) for each AGN, summed over all of the absorbers. These calculations make use of values (or limits) for the radial locations of the absorbers determined from variability, excited-state absorption, or other considerations. From a sample of 10 Seyfert 1 galaxies with detailed photoionization models for their absorbers, we find that 7 have sufficient constraints on the absorber locations to determine Ṁout and LK. The 6 Seyfert 1s with moderate bolometric luminosities (Lbol = 1043 - 1045 ergs s-1) all have mass outflow rates that are 10 - 1000 times the mass accretion rates needed to generate their observed luminosities, indicating that most of the mass outflow originates from outside the inner accretion disk. Three of these (NGC 4051, NGC 3516, and NGC 3783) have LK in the range 0.5 - 5% Lbol, which is the range typically required by feedback models for efficient self-regulation of black-hole and galactic bulge growth. The other three (NGC 5548, NGC 4151, and NGC 7469) have LK > 0.1%Lbol, although these values may increase if radial locations can be determined for more of the absorbers. We conclude that the outflowing UV and X-ray absorbers in moderate-luminosity AGN have the potential to deliver significant feedback to their environments.

  6. Droplets move over viscoelastic substrates by surfing a ridge

    PubMed Central

    Karpitschka, S.; Das, S.; van Gorcum, M.; Perrin, H.; Andreotti, B.; Snoeijer, J. H.

    2015-01-01

    Liquid drops on soft solids generate strong deformations below the contact line, resulting from a balance of capillary and elastic forces. The movement of these drops may cause strong, potentially singular dissipation in the soft solid. Here we show that a drop on a soft substrate moves by surfing a ridge: the initially flat solid surface is deformed into a sharp ridge whose orientation angle depends on the contact line velocity. We measure this angle for water on a silicone gel and develop a theory based on the substrate rheology. We quantitatively recover the dynamic contact angle and provide a mechanism for stick–slip motion when a drop is forced strongly: the contact line depins and slides down the wetting ridge, forming a new one after a transient. We anticipate that our theory will have implications in problems such as self-organization of cell tissues or the design of capillarity-based microrheometers. PMID:26238436

  7. Merkel cells and the individuality of friction ridge skin.

    PubMed

    Kücken, Michael; Champod, Christophe

    2013-01-21

    There is no definite theory yet for the mechanism by which the pattern of epidermal ridges on fingers, palms and soles forming friction ridge skin (FRS) patterns is created. For a long time growth forces in the embryonal epidermis have been believed to be involved in FRS formation. More recent evidence suggests that Merkel cells play an important part in this process as well. Here we suggest a model for the formation of FRS patterns that links Merkel cells to the epidermal stress distribution. The Merkel cells are modeled as agents in an agent based model that move anisotropically where the anisotropy is created by the epidermal stress tensor. As a result ridge patterns are created with pattern defects as they occur in real FRS patterns. As a consequence we suggest why the topology of FRS patterns is indeed unique as the arrangement of pattern defects is sensitive to the initial configuration of Merkel cells.

  8. Contaminated scrap metal management on the Oak Ridge Reservation

    SciTech Connect

    Hayden, H.W.; Stephenson, M.J.; Bailey, J.K.; Weir, J.R.; Gilbert, W.C.

    1993-09-01

    Large quantities of scrap metal are accumulating at the various Department of Energy (DOE) installations across the country as a result of ongoing DOE programs and missions in concert with present day waste management practices. DOE Oak Ridge alone is presently storing around 500,000 tons of scrap metal. The local generation rate, currently estimated at 1,400 tons/yr, is expected to increase sharply over the next couple of years as numerous environmental restoration and decommissioning programs gain momentum. Projections show that 775,000 tons of scrap metal could be generated at the K-25 Site over the next ten years. The Y-12 Plant and Oak Ridge National Laboratory (ORNL) have similar potentials. The history of scrap metal management at Oak Ridge and future challenges and opportunities are discussed.

  9. InP-based deep-ridge NPN transistor laser

    NASA Astrophysics Data System (ADS)

    Liang, S.; Kong, D. H.; Zhu, H. L.; Zhao, L. J.; Pan, J. Q.; Wang, W.

    2011-08-01

    We report an InP-based deep-ridge NPN transistor laser (TL, λ˜1.5μm). By placing the quantum well (QW) active material above the heavily Zn-doped base layer, both the optical absorption of the heavily p-doped base material and the damage of the quality of the QWs resulted from the Zn diffusion into the QWs are decreased greatly. CW operation of the TL is achieved at -40°C, which is much better than the shallow-ridge InP-based NPN TL. With future optimization of the growth procedure, significant improvement of the performance of the deep-ridge InP-based NPN TLs is expected.

  10. InP-based deep-ridge NPN transistor laser.

    PubMed

    Liang, S; Kong, D H; Zhu, H L; Zhao, L J; Pan, J Q; Wang, W

    2011-08-15

    We report an InP-based deep-ridge NPN transistor laser (TL, λ∼1.5 μm). By placing the quantum well (QW) active material above the heavily Zn-doped base layer, both the optical absorption of the heavily p-doped base material and the damage of the quality of the QWs resulted from the Zn diffusion into the QWs are decreased greatly. CW operation of the TL is achieved at -40 °C, which is much better than the shallow-ridge InP-based NPN TL. With future optimization of the growth procedure, significant improvement of the performance of the deep-ridge InP-based NPN TLs is expected.

  11. Modes of faulting at mid-ocean ridges.

    PubMed

    Buck, W Roger; Lavier, Luc L; Poliakov, Alexei N B

    2005-04-07

    Abyssal-hill-bounding faults that pervade the oceanic crust are the most common tectonic feature on the surface of the Earth. The recognition that these faults form at plate spreading centres came with the plate tectonic revolution. Recent observations reveal a large range of fault sizes and orientations; numerical models of plate separation, dyke intrusion and faulting require at least two distinct mechanisms of fault formation at ridges to explain these observations. Plate unbending with distance from the top of an axial high reproduces the observed dip directions and offsets of faults formed at fast-spreading centres. Conversely, plate stretching, with differing amounts of constant-rate magmatic dyke intrusion, can explain the great variety of fault offset seen at slow-spreading ridges. Very-large-offset normal faults only form when about half the plate separation at a ridge is accommodated by dyke intrusion.

  12. Droplets move over viscoelastic substrates by surfing a ridge

    NASA Astrophysics Data System (ADS)

    Karpitschka, S.; Das, S.; van Gorcum, M.; Perrin, H.; Andreotti, B.; Snoeijer, J. H.

    2015-08-01

    Liquid drops on soft solids generate strong deformations below the contact line, resulting from a balance of capillary and elastic forces. The movement of these drops may cause strong, potentially singular dissipation in the soft solid. Here we show that a drop on a soft substrate moves by surfing a ridge: the initially flat solid surface is deformed into a sharp ridge whose orientation angle depends on the contact line velocity. We measure this angle for water on a silicone gel and develop a theory based on the substrate rheology. We quantitatively recover the dynamic contact angle and provide a mechanism for stick-slip motion when a drop is forced strongly: the contact line depins and slides down the wetting ridge, forming a new one after a transient. We anticipate that our theory will have implications in problems such as self-organization of cell tissues or the design of capillarity-based microrheometers.

  13. The Oak Ridge Reservation Annual Site Environmental Report, 2007

    SciTech Connect

    Hughes, Joan; Thompson, Sharon; Page, David

    2008-09-30

    The Oak Ridge Reservation (ORR) consists of three major government-owned, contractor-operated facilities: the Y-12 National Security Complex, Oak Ridge National Laboratory, and East Tennessee Technology Park. The ORR was established in the early 1940s as part of the Manhattan Project, a secret undertaking that produced materials for the first atomic bombs. The reservation’s role has evolved over the years, and it continues to adapt to meet the changing defense, energy, and research needs of the United States. Both the work carried out for the war effort and subsequent research, development, and production activities have involved, and continue to involve, the use of radiological and hazardous materials. The Oak Ridge Reservation Annual Site Environmental Report and supporting data are available at Http://www.ornl.gov/sci/env_rpt or from the project director.

  14. Droplets move over viscoelastic substrates by surfing a ridge.

    PubMed

    Karpitschka, S; Das, S; van Gorcum, M; Perrin, H; Andreotti, B; Snoeijer, J H

    2015-08-04

    Liquid drops on soft solids generate strong deformations below the contact line, resulting from a balance of capillary and elastic forces. The movement of these drops may cause strong, potentially singular dissipation in the soft solid. Here we show that a drop on a soft substrate moves by surfing a ridge: the initially flat solid surface is deformed into a sharp ridge whose orientation angle depends on the contact line velocity. We measure this angle for water on a silicone gel and develop a theory based on the substrate rheology. We quantitatively recover the dynamic contact angle and provide a mechanism for stick-slip motion when a drop is forced strongly: the contact line depins and slides down the wetting ridge, forming a new one after a transient. We anticipate that our theory will have implications in problems such as self-organization of cell tissues or the design of capillarity-based microrheometers.

  15. Composition of basalts from the Mid-Atlantic Ridge

    USGS Publications Warehouse

    Engel, A.E.J.; Engel, C.G.

    1964-01-01

    Studies of volcanic rocks in dredge hauls from the submerged parts of the Mid-Atlantic Ridge suggest that it consists largely of tholeiitic basalt with low values of K, Ti, and P. In contrast, the volcanic islands which form the elevated caps on the Ridge are built of alkali basalt with high values of Ti, Fe3+, P, Na, and K. This distinct correlation between the form of the volcanic structures, elevation above the sea floor, and composition suggests that the islands of alkali basalt are derived from a parent tholeiitic magma by differentiation in shallow reservoirs. The volume of low-potassium tholeiites along the Mid-Atlantic Ridge and elsewhere in the oceans appears to be many times that of the alkali basalts exposed on oceanic islands. Tholeiitic basalts with about 0.2 K2O appear to be the primary and predominant magma erupted on the oceanic floor.

  16. How did the equatorial ridge on Saturn's moon Iapetus form?

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2012-04-01

    Saturn's moon Iapetus is one of the most unusual moons in our solar system. Perhaps the most bizarre feature of Iapetus is its equatorial ridge, a 20-kilometer-high, 200-kilometer-wide mountain range that runs exactly along the equator, circling more than 75% of the moon. No other body in the solar system exhibits such a feature; as Dombard et al. show, previous models have been unable to adequately explain how the ridge formed. The authors propose that the ridge formed from an ancient giant impact that produced a subsatellite around Iapetus. Tidal interactions with Iapetus ultimately led to orbital decay, eventually bringing the subsatellite close enough that the same forces tore it apart, forming a debris ring around Iapetus. Material from this debris ring then rained down on Iapetus, the researchers say, creating the mountain ring along the equator. (Journal of Geophysical Research-Planets, doi:10.1029/2011JE004010, 2012)

  17. Perceptual Learning Solely Induced by Feedback

    PubMed Central

    Choi, Hoon; Watanabe, Takeo

    2012-01-01

    Although feedback is considered to be an important factor in perceptual learning (PL), its role is normally considered limited to facilitation, rather than direct inducement, of PL. Recent studies, however, have suggested feedback to be more actively involved in the inducement of PL. The current study demonstrates an even more significant role for feedback in PL: feedback can evoke PL of a feature without any bottom-up processing of that feature. We use a “fake feedback” method, in which the feedback is related to an arbitrarily chosen feature, rather than actual performance. We find evidence of PL with this fake feedback method both when the learned feature is absent from the visual stimulus (Experiment 1) and when it conflicts with the visual stimulus (Experiment 2). We call this “feedback-based PL,” in contrast with the classical “exposure-based PL.” We find that feedback-based PL and exposure-based PL can occur independently of each other even while occurring in the same paradigm. These results suggest that feedback not only facilitates PL that is evoked by bottom-up information, but that it can directly induce PL, where such feedback-based PL occurs independently of exposure-based PL. PMID:22269189

  18. Improving Feedback with Modern Technology

    NASA Astrophysics Data System (ADS)

    Lee, K. M.; Siedell, C. M.

    2004-12-01

    The teaching of introductory astronomy has undergone a transformation over the last few years due to advancements in technology. The developments make large amounts of feedback available to both student and instructor regarding student understanding of the material. This presentation will look at two components of that evolution -- peer instruction and web-based assessment -- and show how technology is continuing to make ever greater strides by increasing the sophistication of the prompts to which students react. Demonstration of FLASH animations from the ClassAction Project and the Nebraska Astronomy Applet Project will be used to illustrate these ideas. This work is funded by National Science Foundation grants #0231270 and #0404988.

  19. Adaptive-feedback control algorithm.

    PubMed

    Huang, Debin

    2006-06-01

    This paper is motivated by giving the detailed proofs and some interesting remarks on the results the author obtained in a series of papers [Phys. Rev. Lett. 93, 214101 (2004); Phys. Rev. E 71, 037203 (2005); 69, 067201 (2004)], where an adaptive-feedback algorithm was proposed to effectively stabilize and synchronize chaotic systems. This note proves in detail the strictness of this algorithm from the viewpoint of mathematics, and gives some interesting remarks for its potential applications to chaos control & synchronization. In addition, a significant comment on synchronization-based parameter estimation is given, which shows some techniques proposed in literature less strict and ineffective in some cases.

  20. 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.

  1. 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.

  2. Hot spot-ridge crest convergence in the northeast Pacific

    SciTech Connect

    Karsten, J.L.; Delaney, J.R. )

    1989-01-10

    Evolution of the Juan de Fuca Ridge during the past 7 m.y. has been reconstructed taking into account both the propagating rift history and migration of the spreading center in the 'absolute' (fixed hot spot) reference frame. Northwestward migration of the spreading center (at a rate of 30 km/m.y.) has resulted in progressive encroachment of the ridge axis on the Cobb Hot Spot and westward jumping of the central third of the ridge axis more recently than 0.5 Ma. Seamounts in the Cobb-Eickelberg chain are predicted to display systematic variations in morphology and petrology, and a reduction in the age contrast between the edifice and underlying crust, as a result of the ridge axis approach. Relative seamount volumes also indicate that magmatic output of the hot spot varied during this interval, with a reduction in activity between 2.5 and 4.5 Ma, compared with relatively more robust activity before and after this period. Spatial relationships determined in this reconstruction allow hypotheses relating hot spot activity and rift propagation to be evaluated. In most cases, rift propagation has been directed away from the hot spot during the time period considered. Individual propagators show some reduction in propagation rate as separation between the propagating rift tip and hot spot increases, but cross comparison of multiple propagators does not uniformly display the same relationship. No obvious correlation exists between propagation rate and increasing proximity of the hot spot to the ridge axis or increasing hot spot output. Taken together, these observations do not offer compelling support for the concept of hot spot driven rift propagation. However, short-term reversals in propagation direction at the Cobb Offset coincide with activity of the Heckle melting anomaly, suggesting that local propagation effects may be related to excess magma supply at the ridge axis.

  3. Pesticide Leaching from Agricultural Fields with Ridges and Furrows

    PubMed Central

    Boesten, Jos J. T. I.

    2010-01-01

    In the evaluation of the risk of pesticide leaching to groundwater, the soil surface is usually assumed to be level, although important crops like potato are grown on ridges. A fraction of the water from rainfall and sprinkler irrigation may flow along the soil surface from the ridges to the furrows, thus bringing about an extra load of water and pesticide on the furrow soil. A survey of the literature reveals that surface-runoff from ridges to furrows is a well-known phenomenon but that hardly any data are available on the quantities of water and pesticide involved. On the basis of a field experiment with additional sprinkler irrigation, computer simulations were carried out with the Pesticide Emission Assessment at Regional and Local scales model for separate ridge and furrow systems in a humic sandy potato field. Breakthrough curves of bromide ion (as a tracer for water flow) and carbofuran (as example pesticide) were calculated for 1-m depth in the field. Bromide ion leached comparatively fast from the furrow system, while leaching from the ridge system was slower showing a maximum concentration of about half of that for the furrow system. Carbofuran breakthrough from the furrow system began about a month after application and increased steadily to substantial concentrations. Because the transport time of carbofuran in the ridge soil was much longer, no breakthrough occurred in the growing season. The maximum concentration of carbofuran leaching from the ridge–furrow field was computed to be a factor of six times as high as that computed for the corresponding level field. The study shows that the risk of leaching of pesticides via the furrow soil can be substantially higher than that via the corresponding level field soil. PMID:21076668

  4. Sr isotopic variations along the Juan de Fuca Ridge.

    USGS Publications Warehouse

    Eaby, J.; Clague, D.A.; Delaney, J.R.

    1984-01-01

    The Sr isotopic ratios of 39 glass and microcrystalline basalt samples along the Juan de Fuca Ridge and one glass sample from Brown Bear Seamount are at the lower end of the range for normal MORB; the average 87Sr/86Sr ratio is 0.70249 + or - 0.00014 (2sigma ). Although subtle variations exist along the strike of the ridge, the Sr isotopic data do not show systematic variation relative to the proposed Cobb hotspot. The isotopic data are inconsistent with an enriched mantle-plume origin for the Cobb-Eikelberg Seamount chain.-W.H.B.

  5. Transient Hotspot Motion Induced by Plume-Migrating Ridge Interaction

    NASA Astrophysics Data System (ADS)

    Hall, P. S.; Farahat, N. X.; Kundargi, R.

    2013-12-01

    Paleomagnetic data obtained from the Emperor Seamount Chain shows that the Hawaiian hotspot moved rapidly (~40 mm/yr) southward relative to the Earth's magnetic poles during the period of 81- 47 Ma before coming to rest at its present latitude, suggesting that this abrupt change in the motion of the hotspot created the prominent bend in the Hawaii-Emperor Seamount Chain (HESC) [Tarduno et al., 2003]. Tarduno et al. [2009] proposed that this period of rapid hotspot motion might have been the surface expression of the conduit of the presumed Hawaiian plume being entrained and tilted by the passage of a migrating mid-ocean ridge (the Pacific-Kula ridge system) over the plume. While geophysical and geochemical observations have suggested that ridges can influence the dispersion of plumes in the upper mantle at great distances (>1000 km), much about the interaction between mantle plumes and mid-ocean ridges remains poorly understood. We report on a series of 2-D numerical and 3-D analog geodynamic experiments in which a mid-ocean ridge migrates over a mantle plume. These experiments were undertaken to characterize variations in the location of plume-derived melt as the system evolves through time. A range of values for plume excess temperature, plume conduit width, spreading rate and ridge migration rate were investigated so as to fully evaluate the behavior of the system. We find that both the location of the maximum flux of plume-derived melt and the total area over which plume melt is generated vary systemically over the course of the experiments. Most notably, as the ridge moves away from the plume conduit, the area from which plume-derived melts are generated gradually expands in the direction of ridge migration until it reaches a maximum extent, after which it rapidly collapses back towards the plume conduit. The edge of this zone of plume-derived melting can extend as much as 1500 km from the plume conduit, and upon reaching its maximum extent it retreats towards

  6. Using ridge regression in systematic pointing error corrections

    NASA Technical Reports Server (NTRS)

    Guiar, C. N.

    1988-01-01

    A pointing error model is used in the antenna calibration process. Data from spacecraft or radio star observations are used to determine the parameters in the model. However, the regression variables are not truly independent, displaying a condition known as multicollinearity. Ridge regression, a biased estimation technique, is used to combat the multicollinearity problem. Two data sets pertaining to Voyager 1 spacecraft tracking (days 105 and 106 of 1987) were analyzed using both linear least squares and ridge regression methods. The advantages and limitations of employing the technique are presented. The problem is not yet fully resolved.

  7. Near-ridge seamount chains in the northeastern Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Clague, David A.; Reynolds, Jennifer R.; Davis, Alicé S.

    2000-07-01

    High-resolution bathymetry and side-scan data of the Vance, President Jackson, and Taney near-ridge seamount chains in the northeast Pacific were collected with a hull-mounted 30-kHz sonar. The central volcanoes in each chain consist of truncated cone-shaped volcanoes with steep sides and nearly flat tops. Several areas are characterized by frequent small eruptions that result in disorganized volcanic regions with numerous small cones and volcanic ridges but no organized truncated conical structure. Several volcanoes are crosscut by ridge-parallel faults, showing that they formed within 30-40 km of the ridge axis where ridge-parallel faulting is still active. Magmas that built the volcanoes were probably transported through the crust along active ridge-parallel faults. The volcanoes range in volume from 11 to 187 km3, and most have one or more multiple craters and calderas that modify their summits and flanks. The craters (<1 km diameter) and calderas (>1 km diameter) range from small pit craters to calderas as large as 6.5×8.5 km, although most are 2-4 km across. Crosscutting relationships commonly show a sequence of calderas stepping toward the ridge axis. The calderas overlie crustal magma chambers at least as large as those that underlie Kilauea and Mauna Loa Volcanoes in Hawaii, perhaps 4-5 km in diameter and ˜1-3 km below the surface. The nearly flat tops of many of the volcanoes have remnants of centrally located summit shields, suggesting that their flat tops did not form from eruptions along circumferential ring faults but instead form by filling and overflowing of earlier large calderas. The lavas retain their primitive character by residing in such chambers for only short time periods prior to eruption. Stored magmas are withdrawn, probably as dikes intruded into the adjacent ocean crust along active ridge-parallel faults, triggering caldera collapse, or solidified before the next batch of magma is intruded into the volcano, probably 1000-10,000 years

  8. Spreading Dynamics of an Intermediate Ridge: Endeavour Segment of the Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Scott, S. R.; Ramos, F. C.; Gill, J. B.

    2011-12-01

    U/Th disequilibria analyses of 36 on- and off-axis MORB samples from the Endeavour segment of the Juan de Fuca Ridge, an intermediate spreading ridge off the Pacific Northwest coast of the USA, reflect recent spreading and time-integrated geochemical variability. Previous major and trace element and isotopic data from Endeavour samples exhibit a wide range of geochemical characteristics for samples within close spatial proximity, including EMORB, TMORB and NMORB. Morphology of Endeavour constrains lavas erupted on-axis to flow within the current axial valley, preventing axial lavas from flowing off-axis. This relationship can be used to date any MORB found outside of the axial valley, assuming all types lie on a single zero-age line from the most depleted to most enriched lavas. U-Th data indicate that all EMORB and the majority of TMORB are zero-age (<10 ka) within error and lie on a single zero-age line. EMORB with equivalent (within error) young ages on both sides of the axial valley and that span across the entire eastern flank of the ridge erupted prior to the formation of the current axial valley and within a short time interval (<10 ky). If the axial valley formed within the last 10 ky, the minimum full spreading rate falls around 8 cm/yr. If the majority of EMORB are <8 ka, the axial valley may have formed at a full spreading rate of 10 cm/yr or greater. These U-Th age constraints on EMORB yield a spreading rate faster than the time-integrated spreading rate (5 cm/yr). An EMORB sample located furthest east of the axis is at least 70 ky younger than expected based on the time-integrated spreading rate (5 cm/yr). One on-axis TMORB is not within error of the E-T zero-age line, and may be as old as 17 ka. U-Th ages of TMORB from the western flank fall between 25 and ~100 ka, older than all EMORB. NMORB generally have higher Th isotope ratios than E- or TMORB for a given U/Th ratio and lie on a second zero-age line. One NMORB, on the far western flank, is ~40 ky

  9. Generative model for feedback networks

    NASA Astrophysics Data System (ADS)

    White, Douglas R.; Kejžar, Nataša; Tsallis, Constantino; Farmer, Doyne; White, Scott

    2006-01-01

    We propose a model for network formation and study some of its statistical properties. The motivation for the model comes from the growth of several kinds of real networks (i.e., kinship and trading networks, networks of corporate alliances, networks of autocatalytic chemical reactions). These networks grow either by establishing closer connections by adding links in the existing network or by adding new nodes. A node in these networks lacks the information of the entire network. In order to establish a closer connection to other nodes it starts a search in the neighboring part of the network and waits for a possible feedback from a distant node that received the “searching signal.” Our model imitates this behavior by growing the network via the addition of a link that creates a cycle in the network or via the addition of a new node with a link to the network. The forming of a cycle creates feedback between the two ending nodes. After choosing a starting node, a search is made for another node at a suitable distance; if such a node is found, a link is established between this and the starting node, otherwise (such a node cannot be found) a new node is added and is linked to the starting node. We simulate this algorithm and find that we cannot reject the hypothesis that the empirical degree distribution is a q -exponential function, which has been used to model long-range processes in nonequilibrium statistical mechanics.

  10. RF power recovery feedback circulator

    DOEpatents

    Sharamentov, Sergey I [Bolingbrook, IL

    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.

  11. Climate Change and Aerosol Feedbacks

    NASA Astrophysics Data System (ADS)

    Norman, Ann-Lise

    2008-05-01

    Climate instability is expected as mixing ratios of greenhouse gases in the Earth's atmosphere increase. The current trend in rising temperature can be related to anthropogenic greenhouse gas emissions. However, this trend may change as feedback mechanisms amplify; one of the least-understood aspects of climate change. Formation of cloud condensation nuclei from rising sulfate concentrations in the atmosphere may counteract the current warming trend. A key point is where the sulfate, and cloud condensation nuclei are formed. Is cloud formation widespread or localized near sulfate emission sources? A major source of atmospheric sulfate is dimethylsulfide, a compound related to biotic turnover in the surface ocean that constitutes a widespread natural source of aerosols over the remote ocean. A second major source contributing a significant proportion of atmospheric sulfate in the northern hemisphere is produced over continents from industrial activities and fossil fuel combustion. Distinguishing the source of sulfate in well-mixed air is important so that relationships with cloud formation, sea-ice in polar regions, and albedo can be explored. This distinction in sulfate sources can be achieved using isotope apportionment techniques. Recent measurements show an increase in biogenic sulfate coincident with rising temperatures in the Arctic and large amounts sulfur from DMS oxidation over the Atlantic, potentially indicating a widespread biotic feedback to warming over northern oceans.

  12. Surface radiological investigation of Trench 5 in Waste Area Grouping 7 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Goff, D.D.

    1991-08-01

    A surface radiological investigation of areas encompassing Trench 5 on the Oak Ridge Reservation (ORR) was conducted from May 1990 through November 1990. This survey was led by the author, assisted by various members of the Measurement Applications and Development (MAD) group of the Health and Safety Research Division (HASRD) of Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. The purpose of the investigation was to determine the presence, nature, and extent of surface radiological contamination at Trench 5, the Homogeneous Reactor Experiment fuel wells, and surrounding areas. Based on the data obtained in the field, interim corrective measures were recommended to limit human exposure to radioactivity and to minimize insult to the environment. It should be stressed that this project was not intended to be a complete site characterization but rather to be a preliminary investigation into the potential contamination problem that might exist as a result of past operations at Trench 5.

  13. 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.

  14. 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.

  15. Soil Management Plan for the Oak Ridge Y-12 National Security Complex Oak Ridge, Tennessee

    SciTech Connect

    2005-03-02

    This Soil Management Plan applies to all activities conducted under the auspices of the National Nuclear Security Administration (NNSA) Oak Ridge Y-12 National Security Complex (Y-12) that involve soil disturbance and potential management of waste soil. The plan was prepared under the direction of the Y-12 Environmental Compliance Department of the Environment, Safety, and Health Division. Soil disturbances related to maintenance activities, utility and building construction projects, or demolition projects fall within the purview of the plan. This Soil Management Plan represents an integrated, visually oriented, planning and information resource tool for decision making involving excavation or disturbance of soil at Y-12. This Soil Management Plan addresses three primary elements. (1) Regulatory and programmatic requirements for management of soil based on the location of a soil disturbance project and/or the regulatory classification of any contaminants that may be present (Chap. 2). Five general regulatory or programmatic classifications of soil are recognized to be potentially present at Y-12; soil may fall under one or more these classifications: (a) Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) pursuant to the Oak Ridge Reservation (ORR) Federal Facilities Agreement; (b) Resource Conservation and Recovery Act (RCRA); (c) RCRA 3004(u) solid waste managements units pursuant to the RCRA Hazardous and Solid Waste Amendments Act of 1984 permit for the ORR; (d) Toxic Substances and Control Act-regulated soil containing polychlorinated biphenyls; and (e) Radiologically contaminated soil regulated under the Atomic Energy Act review process. (2) Information for project planners on current and future planned remedial actions (RAs), as prescribed by CERCLA decision documents (including the scope of the actions and remedial goals), land use controls implemented to support or maintain RAs, RCRA post-closure regulatory requirements for

  16. Discharge Competence and Pattern Formation in Peatlands: A Meta-Ecosystem Model of the Everglades Ridge-Slough Landscape

    PubMed Central

    Heffernan, James B.; Watts, Danielle L.; Cohen, Matthew J.

    2013-01-01

    Regular landscape patterning arises from spatially-dependent feedbacks, and can undergo catastrophic loss in response to changing landscape drivers. The central Everglades (Florida, USA) historically exhibited regular, linear, flow-parallel orientation of high-elevation sawgrass ridges and low-elevation sloughs that has degraded due to hydrologic modification. In this study, we use a meta-ecosystem approach to model a mechanism for the establishment, persistence, and loss of this landscape. The discharge competence (or self-organizing canal) hypothesis assumes non-linear relationships between peat accretion and water depth, and describes flow-dependent feedbacks of microtopography on water depth. Closed-form model solutions demonstrate that 1) this mechanism can produce spontaneous divergence of local elevation; 2) divergent and homogenous states can exhibit global bi-stability; and 3) feedbacks that produce divergence act anisotropically. Thus, discharge competence and non-linear peat accretion dynamics may explain the establishment, persistence, and loss of landscape pattern, even in the absence of other spatial feedbacks. Our model provides specific, testable predictions that may allow discrimination between the self-organizing canal hypotheses and competing explanations. The potential for global bi-stability suggested by our model suggests that hydrologic restoration may not re-initiate spontaneous pattern establishment, particularly where distinct soil elevation modes have been lost. As a result, we recommend that management efforts should prioritize maintenance of historic hydroperiods in areas of conserved pattern over restoration of hydrologic regimes in degraded regions. This study illustrates the value of simple meta-ecosystem models for investigation of spatial processes. PMID:23671708

  17. Calendar year 1994 groundwater quality report for the Chestnut Ridge Hydrogeologic Regime, Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    1995-09-01

    This groundwater quality report (GWQR) contains an evaluation of the groundwater quality data obtained during the 1994 calendar year (CY) at several hazardous and non-hazardous waste management facilities associated with the US Department of Energy (DOE) Y-12 Plant located on the DOE Oak Ridge Reservation (ORR) southeast of Oak Ridge, Tennessee (Figure 1). These sites lie within the boundaries of the Chestnut Ridge Hydrogeologic Regime (Chestnut Ridge Regime), which is one of three hydrogeologic regimes defined for the purposes of groundwater quality monitoring at the Y-12 Plant (Figure 2). The Environmental Management Department of the Y-12 Plant Health, Safety, Environment, and Accountability (HSEA) Organization manages the groundwater monitoring activities in each regime under the auspices of the Y-12 Plant Groundwater Protection Program (GWPP). The purpose of the GWPP is to characterize the hydrogeology and to monitor groundwater quality at the Y-12 Plant and surrounding area to protect local groundwater resources in accordance with federal, state, and local regulations, DOE Orders, and Lockheed Martin Energy Systems, Inc. (Energy Systems) corporate policy. The annual GWQR for the Chestnut Ridge Regime is completed in two parts. Part 1 consists primarily of data appendices and serves as a reference for the groundwater quality data obtained each CY under the lead of the Y-12 Plant GWPP. Because it contains information needed to comply with reporting requirements of Resource Conservation and Recovery Act (RCRA) interim status assessment monitoring, the Part 1 GWQR is submitted to the Tennessee Department of Environment and Conservation (TDEC) by the RCRA reporting deadline (March 1 of the following CY); Energy Systems submitted the 1994 Part 1 GWQR for the Chestnut Ridge Regime to the TDEC in February 1995 (HSW Environmental Consultants, Inc. 1995a).

  18. 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.

  19. 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.

  20. 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.

  1. [Complex biotechnical feedback in electrostimulation systems].

    PubMed

    Osipov, A N; Dik, S K; Senkovskiĭ, K G

    2002-01-01

    Basic principles in design of electrostimulating equipment with complex biotechnical coupling combining biotechnical feedback and biological feedback are formulated. Realization of these principles in one system leads to qualitatively new capacities of enhancing the efficiency of implemented rehabilitative measures, which is the basis of the designed multichannel electromyostimulation device MYOS having a complex biotechnical feedback, which is used to treat a number of central and peripheral motor disorders (paralyses, pareses), to correct movements, to learn motor skills during training, etc.

  2. Studies Of Positive-Position-Feedback Control

    NASA Technical Reports Server (NTRS)

    Fanson, James L.; Caughey, Thomas K.

    1992-01-01

    Report discusses theoretical and experimental studies of positive-position-feedback control for suppressing vibrations in large flexible structures. Positive-position-feedback control involves placement of actuators and sensors on structure; control voltages applied to actuators in response to outputs of sensors processed via compensator algorithm. Experiments demonstrate feasibility of suppressing vibrations by positive position feedback, and spillover of vibrational energy into uncontrolled modes has stabilizing effect if control gain sufficiently small.

  3. Southern Juan De Fuca Ridge and Escanaba Trough, Gorda Ridge: Comparison of hydrothermal deposits in sediment-free and sediment-covered ridge settings

    SciTech Connect

    Benninger, L.M.; Randolph, M.; Koski, A.; Zierenberg, R.A. )

    1990-06-01

    Southern Juan De Fuca Ridge (SJDF) is a low-relief, sediment-starved ridge axis that has a total opening rate of 6 cm/year and is characterized by lobate and brecciated sheet flows and pillows of MORB composition. Sulfide deposits form at {approximately}2,200 m water depth and are concentrated within a narrow graben centered within the ridge axial valley. Solitary and coalesced chimneys (0.25 to 12 m high) rise directly from the basalt basement and are composed predominantly of Zn sulfide accompanied by Fe and Cu-Fe sulfide and traces of Pb sulfide. Anhydrite occurs as a minor phase in some chimneys. Sulfide chimneys were formed by rapid-venting of high temperature ({approximately}285{degree}C) fluids. These acidic fluids (pH {approximately}3.5) are enriched in Cl, Na, and Ca and are depleted in Cu and Zn. In contrast to SJDF, Escanaba Trough (ET) is spreading at {approximately}2.3 cm/year and has the high relief and axial graben morphology typical of the slow-spreading Mid-Atlantic Ridge. The floor of the axial valley is buried by up to 500 m of clay and terrigenous silt. Rare basement exposures reveal unbrecciated sheet flows and pillow basalts of MORB composition. Large chimney-topped sulfide mounds up to 20 m high and hundreds of meters in extent occur at {approximately}3,250 m water depth at the base of sediment hills; sulfide veins, small chimneys, and clastic deposits occur on, and within, the sediment between hills. Two distinct sulfide types occur at ET. Pyrrhotite-rich sulfide is enriched in Fe, Cu, and As and is associated with low-velocity venting of warm (<220{degree} C) alkaline (pH {approximately}5.4) fluids that are currently depositing anhydrite and barite sinter deposits on top of the sulfide mounds.

  4. Surface radiological investigations along State Highway 95, Lagoon Road, and Melton Valley Drive, Oak Ridge Reservation, Oak Ridge, Tennessee

    SciTech Connect

    Tiner, P.F.; Uziel, M.S.; Rice, D.E.; Williams, J.K.

    1995-08-01

    The surface radiological investigation along State Highway 95, Lagoon Road, and Melton Valley Drive at the Oak Ridge Reservation was conducted as part of the Oak Ridge National Laboratory Environmental Restoration Program Surveillance and Maintenance activities. This report was prepared to document results of the investigation and subsequent remedial actions. The report details surface gamma radiation levels including gamma anomalies; surface beta radiation levels including beta anomalies; results of analysis of soil, water, and vegetation samples and smear samples collected from paved surfaces; remediation activities conducted as a result of the survey; and recommendations for further corrective measures.

  5. Constraints on the Longwave Cloud Altitude Feedback

    NASA Astrophysics Data System (ADS)

    Zelinka, M. D.; Klein, S. A.

    2011-12-01

    Cloud feedback represents the source of largest spread among global climate model projections of future climate change. Though most studies to date have focused on the large spread in cloud feedback that arises from disparate responses of subtropical low clouds, we show using a new technique for quantifying the contribution to cloud feedback from individual cloud types that a significant spread exists in the response of high clouds, with implications for both longwave and shortwave feedbacks. In this talk, we focus on the inter-model spread in longwave altitude feedback, defined as the impact on top of atmosphere longwave fluxes due solely to changes in the vertical distribution of clouds, holding both the total amount and the optical depth distribution fixed. Among the ten models analyzed, this feedback varies from 0.06 to 0.80 W m-2 K-1. We show that the magnitude of this feedback is dependent on two key variables: the effective high cloud amount in the control climate and the change in mean cloud top pressure under doubling of CO2. The latter component is governed by the degree to which the troposphere deepens under doubling of CO2, suggesting an inverse relationship with the lapse rate feedback. To the extent that realistic bounds can be placed on effective high cloud amount using observations, the range of plausible longwave cloud altitude feedback magnitudes can be further reduced.

  6. Wingful, an extracellular feedback inhibitor of Wingless

    PubMed Central

    Gerlitz, Offer; Basler, Konrad

    2002-01-01

    Secreted peptide signals control many fundamental processes during animal development. Proper responses to these signals require cognate inducible feedback antagonists. Here we report the identification of a novel Drosophila Wingless (Wg) target gene, wingful (wf), and show that it encodes a potent extracellular feedback inhibitor of Wg. In contrast to the cytoplasmic protein Naked cuticle (Nkd), the only known Wg feedback antagonist, Wf functions during larval stages, when Nkd function is dispensable. We propose that Wf may provide feedback control for the long-range morphogen activities of Wg. PMID:12000788

  7. Characterizing Microorganisms in Pillow Lava From the East Indian Ridge and From the Arctic Ridges

    NASA Astrophysics Data System (ADS)

    Lysnes, K.; Steinsbu, B. O.; Einen, J.; Torsvik, T.; Thorseth, I. H.; Pedersen, R. B.

    2001-12-01

    Microbial investigations has been carried out on basalts drilled from 10-30 Ma oceanic crust north of the Australian-Antarctic Discordance (ODP Leg 187) and dredged from the neovolcanic zones of the Mohns and Knipovich Ridges (Norwegian-Greenland Sea). The main objectives with the study are to document microbial diversity of the oceanic subsurface biosphere, and in particular to identify microorganisms participating in basalt alteration. Microorganisms in the pillow lava were characterized using enrichment techniques and DNA based methods. Cultivation experiments were started on board immediately after collecting the samples. Seawater and sediment samples were collected for comparison. The enrichment culture media were aimed at microorganisms participating in the iron, manganese, sulfur, and methane cycles. DNA, extracted directly from basalt, sediment and seawater, and from enrichment cultures, was used for PCR, DGGE and 16S rDNA sequencing. Results from enrichment studies, chemical analysis of metabolic products and DNA based techniques show that iron and manganese oxidizing and reducing bacteria, methanotrophic bacteria, and methanogenic Archaea are present in the basalt samples. These main functional groups of bacteria were found in both the 10-30 Ma drill samples and the neovolcanic dredge samples. The DNA based techniques reveal that the native basalt samples contain mostly uncultured and unidentified groups of microbes. Sulfate reducing bacteria were not abundant in the basalt samples, but were common in the seawater and sediment samples.

  8. Environmental monitoring plan for Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1995-09-01

    This document presents an Environmental Monitoring Plan (EMP) for Waste Area Grouping (WAG 6) at Oak Ridge National Laboratory (ORNL). This document updates a draft monitoring plan developed in 1993. The draft plan was never finalized awaiting resolution of the mechanisms for addressing RCRA concerns at a site where the CERCLA process resulted in a decision to defer action, i.e., postpone closure indefinitely. Over the past two years the Tennessee Department of Environment and Conservation (TDEC), US Department of Energy (DOE), and US Environmental Protection Agency (EPA) Region IV, have agreed that RCRA authority at the site will be maintained through a post- closure permit; ``closure`` in this case referring to deferred action. Both a Revised Closure Plan (DOE 1995a) and a Post-Closure Permit Application (DOE 1995b) have been developed to document this agreement; relevant portions of the EMP will be included in the RCRA Post-Closure Permit Application. As the RCRA issues were being negotiated, DOE initiated monitoring at WAG 6. The purpose of the monitoring activities was to (1) continue to comply with RCRA groundwater quality assessment requirements, (2) install new monitoring equipment, and (3) establish the baseline conditions at WAG 6 against which changes in contaminant releases could be measured. Baseline monitoring is scheduled to end September 30, 1995. Activities that have taken place over the past two years are summarized in this document.

  9. Environmental Monitoring Plan for Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1993-09-01

    This document presents the Environmental Monitoring Plan (EMP) for Waste Area Grouping (WAG) 6 at the Oak Ridge National Laboratory (ORNL). Based on the results of the Resource Conservation and Recovery Act (RCRA) Facility Investigation (RFI) and on subsequent discussions with regulators, a decision was made to defer implementing source control remedial measures at the WAG. The alternative selected to address the risks associated with WAG 6 involves maintenance of site access controls prevent public exposure to on-site contaminants, continued monitoring of contaminant releases determine if source control measures are required, and development of technologies that could support the final remediation of WAG 6. Although active source control measures are not being implemented at WAG 6, environmental monitoring is necessary to ensure that any potential changes in contaminant release from the WAG are identified early enough to take appropriate action. Two types of environmental monitoring will be conducted: baseline monitoring and annual routine monitoring. The baseline monitoring will be conducted to establish the baseline contaminant release conditions at the WAG, confirm the site-related chemicals of concern (COCs), and gather data to confirm the site hydrologic model. The baseline monitoring is expected to begin in 1994 and last for 12--18 months. The annual routine monitoring will consist of continued sampling and analyses of COCs to determine off-WAG contaminant flux and risk, identify mills in releases, and confirm the primary contributors to risk. The annual routine monitoring will continue for {approximately} 4 years after completion of the baseline monitoring.

  10. Surface debris inventory at White Wing Scrap Yard, Oak Ridge Reservation, Oak Ridge, Tennessee

    SciTech Connect

    Rodriguez, R.E.; Tiner, P.F.; Williams, J.K.

    1992-08-01

    An inventory of surface debris in designated grid blocks at the White Wing Scrap Yard [Waste Area Grouping 11 (WAG 11)] was conducted intermittently from February through June 1992 by members of the Measurement Applications and Development Group, Health and Safety Research Division, Oak Ridge National Laboratory (ORNL) at the request of ORNL Environmental Restoration (ER) Program personnel. The objectives of this project are outlined in the following four phases: (1) estimate the amount (volume) and type (e.g., glass, metal and plastics) of surface waste material in 30 designated grid blocks (100- by 100-ft grids); (2) conduct limited air sampling for organic chemical pollutants at selected locations (e.g., near drums, in holes, or other potentially contaminated areas); (3) conduct a walkover gamma radiation scan extending outward (approximately 50 ft) beyond the proposed location of the WAG 11 perimeter fence; and (4) recommend one grid block as a waste staging area. This recommendation is based on location and accessibility for debris staging/transport activities and on low levels of gamma radiation in the grid block.

  11. Environmental Survey preliminary report, Oak Ridge Gaseous Diffusion Plant, Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1989-02-01

    This report presents the preliminary findings from the first phase of the Environmental Survey of the US Department of Energy's (DOE) Oak Ridge Gaseous Diffusion Plant (ORGDP) conducted March 14 through 25, 1988. The Survey is being conducted by an interdisciplinary team of environmental specialists, led and managed by the Office of Environment, Safety and Health's Office of Environmental Audit. Individual team components are being supplied by a private contractor. The objective of the Survey is to identify environmental risk associated with ORGDP. The Survey covers all environmental media and all areas of environmental regulation. It is being performed in accordance with the DOE Environmental Survey Manual. This phase of the Survey involves the review of existing site environmental data, observations of the operations carried on at ORGDP, and interviews with site personnel. The Survey team developed a Sampling and Analysis Plan to assist in further assessing certain of the environmental problems identified during is on-site activities. The Sampling and Analysis Plan will be executed by Idaho National Engineering Laboratory (INEL). When completed, the results will be incorporated into the ORGDP Survey findings for in inclusion into the Environmental Survey Summary Report. 120 refs., 41 figs., 74 tabs.

  12. 3001 canal radiological characterization and waste removal report, Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Ritchie, M.G.

    1996-12-01

    An underground steel reinforced concrete transfer and storage canal was built in 1943 and operated as an integral part of the Oak Ridge Graphite Reactor Building (3001) until 1963 when the reactor was shutdown. During operation, the canal was used for under water transfer of irradiated materials and other metals from the reactor in Building 3001 to the Building 3019 hot cell for further processing. After shutdown of the reactor, the canal was used for storage of irradiated materials and fission products until 1990 when the larger materials were removed and stored in the Department of Energy (DOE) approved solid waste management storage facilities. At that time it was discovered that a considerable amount of sludge had accumulated over the intervening years and subsequent analysis showed that the sludge contained Resource Conservation and Recovery Act (RCRA) materials that violated quantities allowed by the RCRA regulations. It was also recognized in 1990 that the canal was losing water to evaporation and the ground at the rate of approximately 400 gallons per day. To maintain water quality; i.e., radionuclide content at or near DOE derived concentration guidelines (DCG), the water in the canal is constantly demineralized using a demineralizer in the Building 3001 and demineralized make up water is supplied from the Building 3004 demineralizer. This report summarizes the 301 Canal Cleanup Task and the solid waste removed from the 3001 Canal in 1996.

  13. Removal site evaluation report for the Isotope Facilities at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    1996-07-01

    This removal site evaluation (RmSE) report of the Isotope Facilities at Oak Ridge National Laboratory (ORNL) was prepared to provide the Environmental Restoration Program with information necessary to evaluate whether hazardous and/or radiological contaminants in and around the Isotopes Facility pose a substantial risk to human health or the environment and if remedial site evaluations (RSEs) or removal actions are required. The scope of the project included: (1) a review of historical evidence regarding operations and use of the facility; (2) interviews with facility personnel concerning current and past operating practices; (3) a site inspection; and (4) identification of hazard areas requiring maintenance, removal, or remedial actions. The results of RmSE indicate that no substantial risks exist from contaminants present in the Isotope Facilities because adequate controls and practices exist to protect human health and the environment. The recommended correction from the RmSE are being conducted as maintenance actions; accordingly, this RmSE is considered complete and terminated.

  14. Environmental Survey preliminary report, Oak Ridge National Laboratory (X-10), Oak Ridge, Tennessee

    SciTech Connect

    Not Available

    1988-07-01

    This report presents the preliminary findings from the first phase of the Environmental Survey of the US Department of Energy (DOE) Oak Ridge National Laboratory (ORNL), X-10 site, conducted August 17 through September 4, 1987. The Survey is being conducted by an interdisciplinary team of environmental specialists, led and managed by the Office of Environment, Safety and Health's Office of Environmental Audit. Individual team specialists are outside experts supplied by a private contractor. The objective of the Survey is to identify environmental problems and areas of environmental risk associated with ORNL. The Survey covers all environmental media and all areas of environmental regulation. It is being performed in accordance with the DOE Environmental Survey Manual. The on-site phase of the Survey involves the review of existing site environmental data, observations of the operations carried on at ORNL, and interviews with site personnel. The Survey team developed a Sampling and Analysis Plan to assist in further assessing certain of the environmental problems identified during its on-site activities. The Sampling and Analysis Plan will be executed by a DOE National Laboratory or a support contractor. When completed, the results will be incorporated into the Environmental Survey Interim Report for ORNL. The Interim Report will reflect the final determinations of the ORNL Survey. 120 refs., 68 figs., 71 tabs.

  15. Screening of contaminants in Waste Area Grouping 2 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    SciTech Connect

    Blaylock, B.G.; Frank, M.L.; Hoffman, F.O.; Hook, L.A.; Suter, G.W.; Watts, J.A.

    1992-07-01

    Waste Area Grouping 2 (WAG 2) of the Oak Ridge National Laboratory (ORNL) is located in the White Oak Creek Watershed and is composed of White Oak Creek Embayment, White Oak Lake and associated floodplain, and portions of White Oak Creek (WOC) and Melton Branch downstream of ORNL facilities. Contaminants leaving other ORNL WAGs in the WOC watershed pass through WAG 2 before entering the Clinch River. Health and ecological risk screening analyses were conducted on contaminants in WAG 2 to determine which contaminants were of concern and would require immediate consideration for remedial action and which contaminants could be assigned a low priority or further study. For screening purposes, WAG 2 was divided into four geographic reaches: Reach 1, a portion of WOC; Reach 2, Melton Branch; Reach 3, White Oak Lake and the floodplain area to the weirs on WOC and Melton Branch; and Reach 4, the White Oak Creek Embayment, for which an independent screening analysis has been completed. Screening analyses were conducted using data bases compiled from existing data on carcinogenic and noncarcinogenic contaminants, which included organics, inorganics, and radionuclides. Contaminants for which at least one ample had a concentration above the level of detection were placed in a detectable contaminants data base. Those contaminants for which all samples were below the level of detection were placed in a nondetectable contaminants data base.

  16. Underground storage tank management plan, Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    1997-09-01

    The Underground Storage Tank (UST) Program at the Oak Ridge Y-12 Plant was established to locate UST systems at the facility and to ensure that all operating UST systems are free of leaks. UST systems have been removed or upgraded in accordance with Tennessee Department of Environment and Conservation (TDEC) regulations and guidance. With the closure of a significant portion of the USTs, the continuing mission of the UST Management Program is to manage the remaining active UST systems and continue corrective actions in a safe regulatory compliant manner. This Program outlines the compliance issues that must be addressed, reviews the current UST inventory and compliance approach, and presents the status and planned activities associated with each UST system. The UST Program provides guidance for implementing TDEC regulations and guidelines for petroleum UST systems. The plan is divided into three major sections: (1) regulatory requirements, (2) active UST sites, and (3) out-of-service UST sites. These sections describe in detail the applicable regulatory drivers, the UST sites addressed under the Program, and the procedures and guidance for compliance.

  17. The Blue Ridge Dinner Theatre: A Recipe for Success.

    ERIC Educational Resources Information Center

    McCaslin, Nellie

    2002-01-01

    Describes an example of intergenerational theatre--the annual production at the Blue Ridge Dinner Theatre, Ferrum College, Virginia. Notes that in addition to four plays for adults, one play is for family audiences and includes area children. Suggests the program offers patrons quality entertainment, gives unique experience to area children, and…

  18. 9. VIEW FROM MANY PARKS CURVE (ON TRAIL RIDGE ROAD) ...

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

    9. VIEW FROM MANY PARKS CURVE (ON TRAIL RIDGE ROAD) OF HORSESHOE PARK, SHOWING FALL RIVER ROAD FAINTLY AT LEFT AT BASE OF SHEEP MOUNTAIN AND CROSSING ALLUVIAL FAN FROM LAWN LAKE FLOOD. - Fall River Road, Between Estes Park & Fall River Pass, Estes Park, Larimer County, CO

  19. Link between ridge subduction and gold mineralization in southern Alaska

    USGS Publications Warehouse

    Haeussler, Peter J.; Bradley, Dwight C.; Goldfarb, Richard; Snee, Lawrence W.; Taylor, Cliff D.

    1995-01-01

    40Ar/39Ar geochronology reveals that turbidite-hosted gold deposits in the southern Alaska accretionary prism are the same age as nearby near-trench plutons. These early Tertiary plutons and gold lodes formed above a slab window during subduction of an oceanic spreading center. Ridge subduction is a previously unrecognized tectonic process for the generation of lode gold.

  20. Remanent magnetization model for the broken ridge satellite magnetic anomaly

    NASA Technical Reports Server (NTRS)

    Johnson, B. D.

    1983-01-01

    A crustal model for the interpretation of the Broken Ridge satellite magnetic anomaly was constructed from bathymetric data assuming an Airy-type isostatic compensation. An average crustal magnetization of 6 A.m is required to account for the observed anomaly amplitudes provided that the whole crust is homogeneously magnetized. In contrast, a model representing only the topographic expression of the Broken Ridge, above the surrounding sea floor, requires a magnetization of the order of 40 A.m-1. Since this latter figure is much higher than is to be expected from studies of magnetic properties of oceanic rocks, it is concluded that the majority of the crustal volume of Broken Ridge is magnetized relatively uniformly. The direction of the source magnetization is consistent with an inclination shallower than the present geomagnetic field and close to that of an axial dipole. Since a more northerly source location for Broken Ridge is contrary to the paleolatitude data it is though that the magnetization represents a magnetization obtained by averaging the geomagnetic field direction over a sufficient time to remove secular variation effects. This pattern is indicative of viscous magnetization.

  1. Technology Solutions Case Study: Foundation Heat Exchanger, Oak Ridge, Tennessee

    SciTech Connect

    2014-03-01

    The foundation heat exchanger, developed by Oak Ridge National Laboratory, is a new concept for a cost-effective horizontal ground heat exchanger that can be connected to water-to-water or water-to-air heat pump systems for space conditioning as well as domestic water heating.

  2. 6. INTERIOR VIEW OF MAIN ROOM SHOWING DAMAGE AT RIDGE ...

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

    6. INTERIOR VIEW OF MAIN ROOM SHOWING DAMAGE AT RIDGE CAUSED BY SOLID ROCKET FUEL BURNING ON AND THROUGH THE ROOF; VIEW TO WEST. - Cape Canaveral Air Station, Launch Complex 17, Facility 36009, East end of Lighthouse Road, Cape Canaveral, Brevard County, FL

  3. Oak Ridge National Laboratory Institutional Plan, FY 1995--FY 2000

    SciTech Connect

    Not Available

    1994-11-01

    This report discusses the institutional plan for Oak Ridge National Laboratory for the next five years (1995-2000). Included in this report are the: laboratory director`s statement; laboratory mission, vision, and core competencies; laboratory plan; major laboratory initiatives; scientific and technical programs; critical success factors; summaries of other plans; and resource projections.

  4. Oak Ridge Reservation Annual Site environmental report for 1994

    SciTech Connect

    Koncinski, W.S.

    1995-10-01

    This report presents the details of the environmental monitoring and management plan for the Oak Ridge Reservation. Topics include: site and operations overview; environmental compliance strategies; environmental management program; effluent monitoring; environmental surveillance; radiation doses; chemical doses; ground water; and quality assurance.

  5. Thermal resistance of ridge-waveguide lasers mounted upside down

    SciTech Connect

    Amann, M.

    1987-01-05

    The heat dissipation in upside down mounted ridge-waveguide lasers equipped with a double-channel structure is analyzed by a simplified device model. Assuming an isothermal active region, the thermal resistance is obtained by means of conformal mapping. A comparison to published experimental results shows good agreement.

  6. 14. VIEW FROM TUNDRA CURVES (ON TRAIL RIDGE ROAD) SHOWING ...

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

    14. VIEW FROM TUNDRA CURVES (ON TRAIL RIDGE ROAD) SHOWING FALL RIVER ROAD RISING FROM BENEATH CHAPIN PASS (AT EXTREME RIGHT) TO FALL RIVER PASS (FAR LEFT). - Fall River Road, Between Estes Park & Fall River Pass, Estes Park, Larimer County, CO

  7. Photolithography fabrication of sol-gel ridge waveguides

    NASA Astrophysics Data System (ADS)

    Sara, Rahmani; Touam, Tahar; Blanchetiere, Chantal; Saddiki, Z.; Saravanamuttu, Kalaichelvi; Du, Xin M.; Chrostowski, Jacek; Andrews, Mark P.; Najafi, S. Iraj

    1998-07-01

    We report on fabrication of ridge waveguides in UV-light sensitive glass sol-gel thin films, deposited on silicon substrate, using a simple photolithography process. The single-layer films are prepared at low temperature and deep UV-light (DUV) is employed to make the waveguides. The effect of fabrication parameters on waveguide shape is investigated.

  8. Oak Ridge Reservation, annual site environmental report for 1993

    SciTech Connect

    Not Available

    1994-11-01

    The US DOE currently oversees activities on the Oak Ridge Reservation, a government-owned, contractor-operated facility. Three sites compose the reservation; Y-12, Oak Ridge National Laboratory, and K-25. This document contains a summary of environmental monitoring activities on the Oak Ridge Reservation (ORR) and its surroundings. The results summarized in this report are based on the data collected during calendar year (CY) 1993 and compiled in; Environmental Monitoring in the Oak Ridge Reservation: CY 1993 Results. Annual environmental monitoring on the ORR consists of two major activities: effluent monitoring and environmental surveillance. Effluent monitoring is the collection and analysis of samples or measurements of liquid, gaseous, or airborne effluents for the purpose of characterizing and quantifying contaminants and process stream characteristics, assessing radiation and chemical exposures to members of the public, and demonstrating compliance with applicable standards. Environmental surveillance is the collection and analysis of samples of air, water, soil, foodstuffs, biota, and other media from DOE sites and their environs and the measurement of external radiation for purposes of demonstrating compliance with applicable standards, assessing radiation and chemical exposures to members of the public, and assessing effects, if any, on the local environment.

  9. Detail of the ridge framing of the clerestory roof, note ...

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

    Detail of the ridge framing of the clerestory roof, note the alternating wood and steel beams, view facing northeast - U.S. Marine Corps Base Hawaii, Kaneohe Bay, Warehouse 250, Aviation Storehouse, C Street between Fifth & Sixth Streets, Kaneohe, Honolulu County, HI

  10. Curvilinear ridges and related features in southwest Cydonia Mensae, Mars

    NASA Technical Reports Server (NTRS)

    Parker, Timothy J.; Schneeberger, Dale M.; Pieri, David C.; Saunders, R. Stephen

    1987-01-01

    Examined is a region on Mars in southwest Cydonia Mensae (32 deg lat., 17 deg long.) just northwest of the lowland/upland boundary escarpment. The dominant morphological features in this region are the clusters of large massifs and plateau outliers (PI), knobby material (K), and smooth lowland plains (Ps). Surrounding the clusters and linking many isolated knobs is a system of curvilinear ridges and arcuate terrain boundaries which tend to separate the massifs and knobs from the smooth plains. Curvilinear ridges are arcuate to nearly linear and smoother in plan than wrinkle ridges and show no apparent correlation with regional structural grain. They are typically 5 to 10 km long but can range from as little as 2 or 3 km to greater than 50 km long. The widths vary from about 100 m to as much as 2 km. Curvilinear ridges are most numerous within 100 km of the lowland/upland boundary escarpment and are associated with massifs and knobby terrain. Arcuate terrain boundaries appear between units of different apparent albedo or arcuate breaks in slope.

  11. Environmental Compliance and Protection Program Description Oak Ridge, Tennessee

    SciTech Connect

    Bechtel Jacobs

    2009-02-26

    The objective of the Environmental Compliance and Protection (EC and P) Program Description (PD) is to establish minimum environmental compliance requirements and natural resources protection goals for the Bechtel Jacobs Company LLC (BJC) Oak Ridge Environmental Management Cleanup Contract (EMCC) Contract Number DE-AC05-98OR22700-M198. This PD establishes the work practices necessary to ensure protection of the environment during the performance of EMCC work activities on the US Department of Energy's (DOE's) Oak Ridge Reservation (ORR) in Oak Ridge, Tennessee, by BJC employees and subcontractor personnel. Both BJC and subcontractor personnel are required to implement this PD. A majority of the decontamination and demolition (D and D) activities and media (e.g., soil and groundwater) remediation response actions at DOE sites on the ORR are conducted under the authority of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). CERCLA activities are governed by individual CERCLA decision documents (e.g., Record of Decision [ROD] or Action Memorandum) and according to requirements stated in the Federal Facility Agreement for the Oak Ridge Reservation (DOE 1992). Applicable or relevant and appropriate requirements (ARARs) for the selected remedy are the requirements for environmental remediation responses (e.g., removal actions and remedial actions) conducted under CERCLA.

  12. Oak Ridge Reservation. Physical Characteristics and National Resources

    SciTech Connect

    Parr, Patricia Dreyer; Joan, F. Hughes

    2006-10-09

    The topology, geology, hydrology, vegetation, and wildlife of the Oak Ridge Reservation (ORR) provide a complex and intricate array of resources that directly impact land stewardship and use decisions. The purpose of this document is to consolidate general information regarding the natural resources and physical characteristics of the ORR.

  13. Geometrical constraints on the evolution of ridged sea ice

    NASA Astrophysics Data System (ADS)

    Amundrud, Trisha L.; Melling, Humfrey; Ingram, R. Grant

    2004-06-01

    A numerical model of the evolving draft distribution of seasonal pack ice is driven by freezing and ice field compression in one dimension. Spatial transects of sea ice draft acquired during winter in the Beaufort Sea are used to evaluate the model. Histograms obtained by ice-profiling sonar on subsea moorings reveal changes in the draft distribution, while observations of ice velocity by Doppler sonar allow calculation of the strain to which the draft distribution is responding. Numerical diffusion in thermal ice growth is controlled using a remapping algorithm. Mechanical redistribution algorithms in common use generate much more deep ridged ice than is observed. Geometric constraints on ridge-keel development that reflect the finite extent of level floes available for ridge building and the true average shape of keels produce more realistic results. In the seasonal pack ice of the Beaufort Sea, 75% of all floes are too small to provide a volume of ice sufficient to construct a keel of draft equal to that commonly assumed in ice dynamics modeling. On average, the distribution of draft within keels has a negative exponential form, implying a cusped keel shape with more area on the thinner flanks than at the crest; models commonly assume a uniform redistribution of ice into a keel of triangular shape. Clearly, the spatial organization of ice within seasonal pack or, equivalently, the existence of ridges and floes should be an acknowledged factor in redistribution theory for pack ice thickness.

  14. Stellar contributions to the hard X-ray galactic ridge

    NASA Technical Reports Server (NTRS)

    Worrall, S. M.; Marshall, F. E.

    1982-01-01

    The number density of serendipitous sources in galactic plane Einstein Observatory IPC fields are compared with predictions based on the intensity of the HEAO-1 A2 unresolved hrd X-ray galactic ridge emission. It is concluded that theoretically predicted X-ray source populations of luminosity 8 x 10 to the 32nd power to 3 x 10 to the 34th power ergs s have 2 KeV to 10 KeV local surface densities of less than approximately .0008 L(32) pc/2 and are unlikely to be the dominant contributors to the hard X-ray ridge. An estimate for Be/neutron star binary systems, such as X Persei, gives a 2 keV to 10 keV local surface density of approximately 26 x 10 to the -5 power L(32) pc/2. Stellar systems of low luminosity, are more likely contributors. Both RS CVn and cataclysmic variable systems contribute 43% + or - 18% of the ridge. A more sensitive measurement of the ridge's hard X-ray spectrum should reveal Fe-line emission. We speculate that dM stars are further major contributors.

  15. Oak Ridge Research reactor shutdown maintenance and surveillance

    SciTech Connect

    Coleman, G.H.; Laughlin, D.L.

    1991-05-01

    The Department of Energy ordered the Oak Ridge Research Reactor to be placed in permanent shutdown on July 14, 1987. The paper outlines routine maintenance activities and surveillance tests performed April through September, 1990, on the reactor instrumentation and controls, process system, and the gaseous waste filter system. Preparations are being made to transfer the facility to the Remedial Action Program. 6 tabs. (MHB)

  16. 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... Reinstatement. The Department of Justice (DOJ), Federal Bureau of Investigation (FBI), Criminal Justice... form/collection: Friction Ridge Cards: Arrest and Institution; Applicant; Personal Identification;...

  17. 75 FR 73069 - Enstor Grama Ridge Storage and Transportation, LLC, Enstor Katy Storage and Transportation, LP...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-29

    ...; Docket No. PR10-83-001] Enstor Grama Ridge Storage and Transportation, LLC, Enstor Katy Storage and Transportation, LP, et al.; Notice of Baseline Filings November 18, 2010. Enstor Grama Ridge Storage Docket...

  18. Are Axial Volcanic Ridges where all the (volcanic) action is?

    NASA Astrophysics Data System (ADS)

    Searle, R. C.

    2012-12-01

    Although axial volcanic ridges (AVRs) are generally recognised as the main loci for lithospheric generation at slow-spreading mid-ocean ridges, various recent studies have suggested that axial volcanism is not confined to them. Here I present evidence from three studies for significant amounts of off-AVR volcanism at three slow-spreading ridges. 1) Near-bottom side-scan sonar (TOBI) images of the Mid-Atlantic Ridge near 13°N show a complex pattern of closely-spaced, active oceanic core complexes (OCCs) where plate separation is largely a-volcanic, separated by short segments of vigorous volcanic spreading. In one such volcanic segment, the brightest sea floor and therefore inferred youngest volcanism occurs not on the topographic axis (an apparently 'old' AVR) but at the edge of a broad axial valley. 2) A similar TOBI survey of the Mid-Cayman Spreading Centre reveals AVRs in the north and south flanking an OCC (Mt. Dent) and a non-volcanic ridge interpreted as tectonically extruded peridotite ('smooth' sea floor). In both AVR segments there are clear, young lava flows that have erupted from perched sources part way up the median valley walls and have partly flowed down into the valley. 3) The third case is from the Mid-Atlantic Ridge at 45°N, where we conducted a detailed geophysical and geological study of an AVR and surrounding median valley floor. The AVR is largely surrounded by flat sea floor composed mainly of lobate and sheet flows, whereas the AVR comprises predominantly pillow lavas. Although we have no firm dates, various indicators suggest most lavas on the AVR are around 10ka old or somewhat less. The apparently youngest (brightest acoustic returns, thinnest sediment cover) of the flat-lying lava flows appears to have a similar age from its degree of sediment cover. Contact relations between these lavas and the AVR flanks show no evidence of a clear age difference between the two, and we think both types of eruption may have occurred roughly

  19. Abyssal Peridotites and Mantle Melting Beneath Ocean Ridges

    NASA Astrophysics Data System (ADS)

    Dick, H. J.; Snow, J. E.; Hellebrand, E.; Shimizu, N.

    2005-12-01

    Studies of abyssal peridotite from ultraslow and slow spreading ridges show significant regional variability; with a strong correlation between the compositions of peridotite averaged by locality and spatially associated MORB reflecting higher degrees of mantle melting near mantle hot spots. Local variability of peridotite compositions, however, is often large, and may equal the regional variability along ocean ridges. The latter is attributed to local melting and melt transport processes such as melt channelization or late-stage melt impregnation in the lithosphere. The observed regional correlation appears only when many samples are averaged to eliminate local and outcrop scale variability. Almost all the peridotites used in these correlations are from transforms, and therefore represent similar thermal and mantle melting histories. Thus, regional differences in mantle composition are preserved. Until recently, little data were available for peridotites away from transforms representing the central mantle environment beneath magmatic segments. This is key, as geophysical and geologic evidence suggest focused melt flow beneath slow spreading ridges. If so, beneath individual magmatic segments there should be a corresponding mantle melting cell in which melt is focused from a broad melting region to a melt transport zone at its mid-point that feeds an overlying crustal magmatic center. High melt fluxes in the transport zone would produce very depleted peridotites stripped of pyroxene by melt-rock reaction during magma ascent. Studies of peridotites far from transforms at ultraslow Gakkel and SW Indian Ridges indicate this is the case: with near-Cpx free intergranular harzburgite and dunite locally abundant in contrast to transform peridotites. Recent mapping of the plutonic foundation of an ancient 35-km long slow spreading ridge segment at the Kane Core Complex also found a narrow 10-km wide zone of focused melt flow through the mantle marked by abundant dunite

  20. The origin, classification and modelling of sand banks and ridges

    NASA Astrophysics Data System (ADS)

    Dyer, Keith R.; Huntley, David A.

    1999-08-01

    Sand banks and elongated sand ridges occur in many coastal and shelf seas where there is abundant sand and where the currents are strong enough to move sediment, but they have a wide variety of forms. Their generation requires a source of mobile sediment, either from the local sea bed, or from coast erosion. Most appear to have been created during the post-glacial rise in sea level, but they have been subsequently modified by changing currents and waves, thus losing their relict characteristics. A descriptive classification scheme is developed to unify the approaches of marine geologists and physical oceanographers, which emphasizes the formation and present hydrodynamic setting in their long-term development. Open shelf linear ridges (Type 1) are up to 80 km long, average 13 km wide and are tens of metres in height. They are oriented at an angle to the flow, are asymmetrical and appear to migrate in the direction of their steep face. They appear to be in near equilibrium with the flow. These contrast with linear ridges formed in mouths of wide estuaries, which are aligned with the flow, and which migrate away from their steeper face (Type2A). In narrow-mouthed estuaries and inlets, tidal currents are strong only close to the mouth and waves are more dominant. The banks then form close to the mouth as ebb and flood deltas (Type 2Bi). When the coast is retreating, the ebb delta forms a primary source of sand to the nearshore region, which can become modified by storm flows into `shore attached ridges' at angles to the coastline (Type 2Bii). Tidal eddies produced by headlands can create `banner banks' (Type 3A), but when the headland is retreating alternating or `en-echelon' ridges can be formed which can become isolated from the coast as it recedes (Type 3B). Coastal retreat and rising sea level can then cause the ridges to become moribund. Thus the majority of ridges rely on sea level rise for their origin. Theoretical and modelling studies of the shorter term

  1. Radiation feedback in dusty clouds

    NASA Astrophysics Data System (ADS)

    Ishiki, Shohei; Okamoto, Takashi

    2017-03-01

    We have investigated the impact of photoionization and radiation pressure on a dusty star-forming cloud using one-dimensional radiation hydrodynamic simulations, which include absorption and re-emission of photons by dust. We find that, in a cloud of mass 105 M⊙ and radius 17 pc, the effect of radiation pressure is negligible when star formation efficiency is 2 per cent. The importance of radiation pressure increases with increasing star formation efficiency or an increasing dust-to-gas mass ratio. The net effect of radiation feedback, however, becomes smaller with the increasing dust-to-gas mass ratio, since the absorption of ultraviolet photons by dust grains suppresses photoionization and hence photoheating.

  2. Biological Feedbacks in Global Desertification

    NASA Astrophysics Data System (ADS)

    Schlesinger, William H.; Reynolds, James F.; Cunningham, Gary L.; Huenneke, Laura F.; Jarrell, Wesley M.; Virginia, Ross A.; Whitford, Walter G.

    1990-03-01

    Studies of ecosystem processes on the Jornada Experimental Range in southern New Mexico suggest that long-term grazing of semiarid grasslands leads to an increase in the spatial and temporal heterogeneity of water, nitrogen, and other soil resources. Heterogeneity of soil resources promotes invasion by desert shrubs, which leads to a further localization of soil resources under shrub canopies. In the barren area between shrubs, soil fertility is lost by erosion and gaseous emissions. This positive feedback leads to the desertification of formerly productive land in southern New Mexico and in other regions, such as the Sahel. Future desertification is likely to be exacerbated by global climate warming and to cause significant changes in global biogeochemical cycles.

  3. Biological feedbacks in global desertification.

    PubMed

    Schlesinger, W H; Reynolds, J F; Cunningham, G L; Huenneke, L F; Jarrell, W M; Virginia, R A; Whitford, W G

    1990-03-02

    Studies of ecosystem processes on the Jornada Experimental Range in southern New Mexico suggest that longterm grazing of semiarid grasslands leads to an increase in the spatial and temporal heterogeneity of water, nitrogen, and other soil resources. Heterogeneity of soil resources promotes invasion by desert shrubs, which leads to a further localization of soil resources under shrub canopies. In the barren area between shrubs, soil fertility is lost by erosion and gaseous emissions. This positive feedback leads to the desertification of formerly productive land in southern New Mexico and in other regions, such as the Sahel. Future desertification is likely to be exacerbated by global climate warming and to cause significant changes in global biogeochemical cycles.

  4. 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.

  5. 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.

  6. Recent and historic drivers of landscape change in the Everglades ridge, slough, and Tree Island mosaic

    USGS Publications Warehouse

    Larsen, Laurel G.; Nicholas Aumen,; Bernhardt, Christopher E.; Vic Engel,; Givnish, Thomas J.; S Hagerthey, P McCormick; Harvey, Judson; Lynn Leonard,; McCormick, P.; McVoy, Christopher; Noe, Gregory; Nungesser, Martha K.; Rutchey, K.; Sklar, Fred; Troxler, Tiffany G.; Volin, John C.; Willard, Debra A.

    2011-01-01

    More than half of the original Everglades extent formed a patterned peat mosaic of elevated ridges, lower and more open sloughs, and tree islands aligned parallel to the dominant flow direction. This ecologically important landscape structure remained in a dynamic equilibrium for millennia prior to rapid degradation over the past century in response to human manipulation of the hydrologic system. Restoration of the patterned landscape structure is one of the primary objectives of the Everglades restoration effort. Recent research has revealed that three main drivers regulated feedbacks that initiated and maintained landscape structure: the spatial and temporal distribution of surface water depths, surface and subsurface flow, and phosphorus supply. Causes of recent degradation include but are not limited to perturbations to these historically important controls; shifts in mineral and sulfate supply may have also contributed to degradation. Restoring predrainage hydrologic conditions will likely preserve remaining landscape pattern structure, provided a sufficient supply of surface water with low nutrient and low total dissolved solids content exists to maintain a rainfall-driven water chemistry. However, because of hysteresis in landscape evolution trajectories, restoration of areas with a fully degraded landscape could require additional human intervention.

  7. Recent and historic drivers of landscape change in the everglades ridge, Slough, and Tree Island Mosaic

    USGS Publications Warehouse

    Larsen, L.; Aumen, N.; Bernhardt, C.; Engel, V.; Givnish, T.; Hagerthey, S.; Harvey, J.; Leonard, L.; McCormick, P.; McVoy, C.; Noe, G.; Nungesser, M.; Rutchey, K.; Sklar, F.; Troxler, T.; Volin, J.; Willard, D.

    2011-01-01

    More than half of the original Everglades extent formed a patterned peat mosaic of elevated ridges, lower and more open sloughs, and tree islands aligned parallel to the dominant flow direction. This ecologically important landscape structure remained in a dynamic equilibrium for millennia prior to rapid degradation over the past century in response to human manipulation of the hydrologic system. Restoration of the patterned landscape structure is one of the primary objectives of the Everglades restoration effort. Recent research has revealed that three main drivers regulated feedbacks that initiated and maintained landscape structure: the spatial and temporal distribution of surface water depths, surface and subsurface flow, and phosphorus supply. Causes of recent degradation include but are not limited to perturbations to these historically important controls; shifts in mineral and sulfate supply may have also contributed to degradation. Restoring predrainage hydrologic conditions will likely preserve remaining landscape pattern structure, provided a sufficient supply of surface water with low nutrient and low total dissolved solids content exists to maintain a rainfall-driven water chemistry. However, because of hysteresis in landscape evolution trajectories, restoration of areas with a fully degraded landscape could require additional human intervention. Copyright ?? 2011 Taylor & Francis Group, LLC.

  8. 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.

  9. Linking playa surface dust emission potential to feedbacks between surface moisture and salt crust expansion through high resolution terrestrial laser scanning measurements

    NASA Astrophysics Data System (ADS)

    Nield, J. M.; King, J.; Wiggs, G.

    2012-12-01

    The dust emissivity of salt pans (or playas) can be significant but is controlled by interactions between wind erosivity, surface moisture, salt chemistry and crust morphology. These surface properties influence the aeolian transport threshold and can be highly variable over both short temporal and spatial scales. In the past, field studies have been hampered by practical difficulties in accurately measuring properties controlling sediment availability at the surface in high resolution. Studies typically therefore, have investigated large scale monthly or seasonal change using remote sensing and assume a homogeneous surface when predicting dust emissivity. Here we present the first high resolution measurements (sub-cm) of salt crust expansion related to changes in diurnal moisture over daily and weekly time periods using terrestrial laser scanning (TLS, ground-based LiDAR) on Sua Pan, Botswana. The TLS measures both elevation and relative surface moisture change simultaneously, without disturbing the surface. Measurement sequences enable the variability in aeolian sediment availability to be quantified along with temporal feedbacks associated with crust degradation. On crusts with well-developed polygon ridges (high aerodynamic and surface roughness), daily surface expansion was greater than 30mm. The greatest surface change occurred overnight on the upper, exposed sections of the ridges, particularly when surface temperatures dropping below 10°C. These areas also experienced the greatest moisture variation and became increasingly moist overnight in response to an increase in relative humidity. In contrast, during daylight hours, the ridge areas were drier than the lower lying inter-ridge areas. Positive feedbacks between surface topography and moisture reinforced the maximum diurnal moisture variation at ridge peaks, encouraging crust thrusting due to overnight salt hydration, further enhancing the surface, and therefore, aerodynamic roughness. These feedbacks

  10. 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…

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

    ERIC Educational Resources Information Center

    Nakata, Tatsuya

    2015-01-01

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

  12. Explanation Feedback Is Better than Correct Answer Feedback for Promoting Transfer of Learning

    ERIC Educational Resources Information Center

    Butler, Andrew C.; Godbole, Namrata; Marsh, Elizabeth J.

    2013-01-01

    Among the many factors that influence the efficacy of feedback on learning, the information contained in the feedback message is arguably the most important. One common assumption is that there is a benefit to increasing the complexity of the feedback message beyond providing the correct answer. Surprisingly, studies that have manipulated the…

  13. 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…

  14. Can Performance Feedback during Instruction Boost Knowledge Acquisition? Contrasting Criterion-Based and Social Comparison Feedback

    ERIC Educational Resources Information Center

    Kollöffel, Bas; de Jong, Ton

    2016-01-01

    Feedback indicating how well students are performing during a learning task can be very stimulating. In this study with a pre- and post-test design, the effects of two types of performance feedback on learning results were compared: feedback during a learning task was either stated in terms of how well the students were performing relative to…

  15. The Impact of Middle-School Students' Feedback Choices and Performance on Their Feedback Memory

    ERIC Educational Resources Information Center

    Cutumisu, Maria; Schwartz, Daniel L.

    2016-01-01

    This paper presents a novel examination of the impact of students' feedback choices and performance on their feedback memory. An empirical study was designed to collect the choices to seek critical feedback from a hundred and six Grade 8 middle-school students via Posterlet, a digital assessment game in which students design posters. Upon…

  16. Pressure Ridge Keel Shapes in the Chukchi and Beaufort Seas

    NASA Astrophysics Data System (ADS)

    Valenti, V. A.; Mahoney, A. R.; Metzger, A.; Eicken, H.

    2014-12-01

    Abstract: Recent aspirations for offshore development in the Chukchi and Beaufort seas, off the North Slope of Alaska, have precipitated the need of additional information for various sea-ice parameters. Of specific interest to engineers and regulatory agencies are the magnitudes of parameters representative of major hazards with a low expectation of occurring over some timeframe. The thickness and width of large pressure ridges that may impact offshore structures is of particular interest. Here, we analyze an extensive dataset from moored ice profiling sonars (IPSs) and acoustic Doppler current profilers (ADCPs) deployed in the vicinity of offshore oil-and-gas lease areas in the US portions of the Chukchi and Beaufort Seas. In all, we examine 16 annual time series of ice draft and velocity from six different mooring locations over five years. Using an automated algorithm, we identify individual pressure ridge keels based on deviations in ice draft from surrounding level ice and derive measurements of the maximum depth and shape of each. Of particular note, and contrary to many idealized ridges portrayed in the literature, we find that flat-bottomed keels are rare in this region. Since the orientation of each ridge as it passes over the mooring is unknown it is not possible to directly measure the precise width. Instead we bin the keels by maximum depth and find the modal width value for each depth bin. Finding that most keels have broadly the same triangular cross-section, we assume the modal width value corresponds to cases when the ridge passes over the mooring approximately perpendicular to its axis. Using this approach, we find a constant ratio between maximum keel depth and width, corresponding to a mean keel slope of around 33 degrees. This is somewhat steeper than is commonly found in literature. We also analyze the relationship between keel depth and drift speed, but find no statistically significant dependence.

  17. Diverse styles of volcanism at slow-spreading ridges (Invited)

    NASA Astrophysics Data System (ADS)

    Yeo, I. A.; Devey, C. W.; Searle, R. C.

    2013-12-01

    Slow-spreading mid-ocean ridge segments display an incredible diversity in morphology as a result of the volcanic processes occurring on them. The may have prominent axial highs or be floored by smooth, tectonised terrains. Where highs are present they may be smooth or hummocky, fill the valley or be surrounded by lower profile lava flows, and may exist not only in the centre, but also at the ends of segments. Individual eruptions may form one or more lava morphologies, be continuous or discontinuous and occur anywhere along the segment. This diversity is illustrated well in bathymetry and sidescan sonar from along the Mid-Atlantic Ridge. Multibeam bathymetry from sites along the MAR reveal large scale differences in morphology between segments, while higher resolution multibeam and sidescan datasets from AUVs alongside video and photographic information from ROVs help to elucidate the detailed volcanic morphologies associated with these larger scale differences. Hummocky terrain and smooth terrain are present in varying proportions on almost all slow-spreading segments, however may form in differing locations, or as parts of larger edifices. For example, smooth volcanic highs are morphologically and probably volcanologically different to hummocky axial volcanic ridges. In this contribution we compare and contrast bathymetric data from a number of different slow-spreading segments, including recently collected bathymetry from previously unsurveyed sections of the southern Mid-Atlantic Ridge, with high-resolution sidescan, multibeam and video observations to look at the variety of volcanic features on slow-spreading ridges and their impact for the construction of the upper oceanic crust.

  18. 78 FR 3028 - Final Environmental Impact Statement for General Management Plan, Blue Ridge Parkway, Virginia...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-15

    ... National Park Service Final Environmental Impact Statement for General Management Plan, Blue Ridge Parkway... the General Management Plan (GMP) for Blue Ridge Parkway (parkway). Consistent with NPS laws... Ridge Parkway, 199 Hemphill Knob Road, Asheville, NC 28803. A limited number of compact disks...

  19. 75 FR 20859 - Temporary Concession Contract for Blue Ridge Parkway, NC/VA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-21

    ... National Park Service Temporary Concession Contract for Blue Ridge Parkway, NC/VA AGENCY: National Park... Blue Ridge Parkway. SUMMARY: Pursuant to 36 CFR 51.24, public notice is hereby given that the National... services within Blue Ridge Parkway, North Carolina and Virginia for a term not to exceed 3 years....

  20. 76 FR 40354 - Notice of Cancellation of Environmental Impact Statement for the Proposed Crowned Ridge Wind...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-08

    ... Crowned Ridge Wind Energy Center Project, Codington and Grant Counties, SD AGENCY: Western Area Power... 150-megawatt Crowned Ridge Wind Energy Center Project (Project) in Codington and Grant counties, South... process for NextEra's proposed Crowned Ridge Wind Energy Center Project with the publication of...