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Sample records for accurate global bio-optical

  1. Automated in situ observations of upper ocean biogeochemistry, bio-optics, and physics and their potential use for global studies

    NASA Technical Reports Server (NTRS)

    Dickey, Tommy D.; Granata, Timothy C.; Taupier-Letage, Isabelle

    1992-01-01

    The processes controlling the flux of carbon in the upper ocean have dynamic ranges in space and time of at least nine orders of magnitude. These processes depend on a broad suite of inter-related biogeochemical, bio-optical, and physical variables. These variables should be sampled on scales matching the relevant phenomena. Traditional ship-based sampling, while critical for detailed and more comprehensive observations, can span only limited portions of these ranges because of logistical and financial constraints. Further, remote observations from satellite platforms enable broad horizontal coverage which is restricted to the upper few meters of the ocean. For these main reasons, automated subsurface measurement systems are important for the fulfillment of research goals related to the regional and global estimation and modeling of time varying biogeochemical fluxes. Within the past few years, new sensors and systems capable of autonomously measuring several of the critical variables have been developed. The platforms for deploying these systems now include moorings and drifters and it is likely that autonomous underwater vehicles (AUV's) will become available for use in the future. Each of these platforms satisfies particular sampling needs and can be used to complement both shipboard and satellite observations. In the present review, (1) sampling considerations will be summarized, (2) examples of data obtained from some of the existing automated in situ sampling systems will be highlighted, (3) future sensors and systems will be discussed, (4) data management issues for present and future automated systems will be considered, and (5) the status of near real-time data telemetry will be outlined. Finally, we wish to make it clear at the outset that the perspectives presented here are those of the authors and are not intended to represent those of the United States JGOFS program, the International JGOFS program, NOAA's C&GC program, or other global ocean programs.

  2. A compilation of global bio-optical in situ data for ocean-colour satellite applications

    NASA Astrophysics Data System (ADS)

    Valente, André; Sathyendranath, Shubha; Brotas, Vanda; Groom, Steve; Grant, Michael; Taberner, Malcolm; Antoine, David; Arnone, Robert; Balch, William M.; Barker, Kathryn; Barlow, Ray; Bélanger, Simon; Berthon, Jean-François; Beşiktepe, Şükrü; Brando, Vittorio; Canuti, Elisabetta; Chavez, Francisco; Claustre, Hervé; Crout, Richard; Frouin, Robert; García-Soto, Carlos; Gibb, Stuart W.; Gould, Richard; Hooker, Stanford; Kahru, Mati; Klein, Holger; Kratzer, Susanne; Loisel, Hubert; McKee, David; Mitchell, Brian G.; Moisan, Tiffany; Muller-Karger, Frank; O'Dowd, Leonie; Ondrusek, Michael; Poulton, Alex J.; Repecaud, Michel; Smyth, Timothy; Sosik, Heidi M.; Twardowski, Michael; Voss, Kenneth; Werdell, Jeremy; Wernand, Marcel; Zibordi, Giuseppe

    2016-06-01

    A compiled set of in situ data is important to evaluate the quality of ocean-colour satellite-data records. Here we describe the data compiled for the validation of the ocean-colour products from the ESA Ocean Colour Climate Change Initiative (OC-CCI). The data were acquired from several sources (MOBY, BOUSSOLE, AERONET-OC, SeaBASS, NOMAD, MERMAID, AMT, ICES, HOT, GeP&CO), span between 1997 and 2012, and have a global distribution. Observations of the following variables were compiled: spectral remote-sensing reflectances, concentrations of chlorophyll a, spectral inherent optical properties and spectral diffuse attenuation coefficients. The data were from multi-project archives acquired via the open internet services or from individual projects, acquired directly from data providers. Methodologies were implemented for homogenisation, quality control and merging of all data. No changes were made to the original data, other than averaging of observations that were close in time and space, elimination of some points after quality control and conversion to a standard format. The final result is a merged table designed for validation of satellite-derived ocean-colour products and available in text format. Metadata of each in situ measurement (original source, cruise or experiment, principal investigator) were preserved throughout the work and made available in the final table. Using all the data in a validation exercise increases the number of matchups and enhances the representativeness of different marine regimes. By making available the metadata, it is also possible to analyse each set of data separately. The compiled data are available at doi:10.1594/PANGAEA.854832 (Valente et al., 2015).

  3. Bio-optical profile data report: Joint Global Ocean Flux Study, Hawaii Ocean Time-Series, HOT-3, R/V Moana Wave, 6-10 January 1989

    NASA Technical Reports Server (NTRS)

    Collins, Donald J.; Rhea, W. Joseph; Tran, An Van

    1990-01-01

    Time-series measurements of the incident surface downwelling irradiance and vertical profiles of the Bio-optical properties of the ocean have been measured during the third cruise of the Hawaii Ocean Time-Series to the ALOHA site, 22 degrees 56.4 minutes N, 157 degrees 54.6 minutes W, north of the island of Oahu, Hawaii, during the period January 6 to 10, 1989. A summary of these data is presented to permit investigators an overview of the data collected. The data are available in digital form for scientific investigators.

  4. Bermuda Bio Optics Project. Chapter 14

    NASA Technical Reports Server (NTRS)

    Nelson, Norm

    2003-01-01

    The Bermuda BioOptics Project (BBOP) is a collaborative effort between the Institute for Computational Earth System Science (ICESS) at the University of California at Santa Barbara (UCSB) and the Bermuda Biological Station for Research (BBSR). This research program is designed to characterize light availability and utilization in the Sargasso Sea, and to provide an optical link by which biogeochemical observations may be used to evaluate bio-optical models for pigment concentration, primary production, and sinking particle fluxes from satellite-based ocean color sensors. The BBOP time-series was initiated in 1992, and is carried out in conjunction with the U.S. JGOFS Bermuda Atlantic Time-series Study (BATS) at the Bermuda Biological Station for Research. The BATS program itself has been observing biogeochemical processes (primary productivity, particle flux and elemental cycles) in the mesotrophic waters of the Sargasso Sea since 1988. Closely affiliated with BBOP and BATS is a separate NASA-funded study of the spatial variability of biogeochemical processes in the Sargasso Sea using high-resolution AVHRR and SeaWiFS data collected at Bermuda (N. Nelson, P.I.). The collaboration between BATS and BBOP measurements has resulted in a unique data set that addresses not only the SIMBIOS goals but also the broader issues of important factors controlling the carbon cycle.

  5. Evaluating a Gulf of Maine Bio-Optics Dataset Using Hydrolight and Simplified Bio-optical Models

    NASA Astrophysics Data System (ADS)

    Szeto, M. J.; Campbell, J.; Moore, T.

    2008-12-01

    One of the central goals of the ocean color community is to estimate global primary productivity. This task is currently attempted using satellite measurements of the reflected light from the upper ocean. The light measurements are processed in ocean color algorithms to produce indicators of change in the biomass, which convey the dynamics of primary productivity. This work involves an evaluation of an in situ bio-optics dataset used to develop and improve ocean color algorithms. The dataset was collected from the western Gulf of Maine by the Coastal Ocean Observing and Analysis Center at the University of New Hampshire. The evaluation entails a comparison of in situ and modeled remote-sensing reflectance (Rrs), an apparent optical property. The modeled Rrs is produced from Hydrolight, a radiative transfer numerical code that uses fundamental physics to calculate Rrs from in situ absorption and scattering measurements (which are inherent optical properties, i.e, IOPs). The IOPs are dependent on ocean constituents including phytoplankton, colored dissolved organic matter (CDOM), and non-algal particles. Because Hydrolight is based on fundamental principles of radiative transfer, its products are not subject to the many sources of uncertainty associated with the in situ measurements. Differences between in situ and modeled Rrs are evaluated systematically through sensitivity testing of various parameters in Hydrolight. The Rrs and IOP data are also examined using simplified bio-optical models that express Rrs as a function of IOPs (Gordon, et al., 1988; Sydor, 2007). These models are currently used as the basis for semi-analytical ocean color algorithms.

  6. A Review of Bio-Optical Chlorophyll Algorithms and Future Challenges

    NASA Astrophysics Data System (ADS)

    O'Reilly, J. E.; Maritorena, S.

    2001-12-01

    The highly successful bio-optical algorithm used in the global processing of CZCS was empirically derived by statistically relating fewer than 60 in situ observations of water-leaving radiance band ratios to phytoplankton pigment concentration. Since then, improvements in empirical algorithms have mostly resulted from the increased quantity, quality and variety of in situ Rrs-chlorophyll data sets acquired during the past decade from many diverse bio-optical provinces of the global ocean. Concurrent improvement in the knowledge of bio-optical principles has resulted in the emergence of more analytic model-based algorithms for estimating chlorophyll and other water constituents. The relative strengths and weaknesses of the various types of algorithms are discussed. Some of the present and near future challenges are also presented: the need for high quality IOP data, the compatibility between regional and global algorithms, the coupling of atmospheric and in-water models, and the integration of data from a variety of ocean color sensors into a complete picture of the distribution of chlorophyll over the global ocean.

  7. Optical closure of parameterized bio-optical relationships

    NASA Astrophysics Data System (ADS)

    He, Shuangyan; Fischer, Jürgen; Schaale, Michael; He, Ming-xia

    2014-03-01

    An optical closure study on bio-optical relationships was carried out using radiative transfer model matrix operator method developed by Freie Universität Berlin. As a case study, the optical closure of bio-optical relationships empirically parameterized with in situ data for the East China Sea was examined. Remote-sensing reflectance ( R rs) was computed from the inherent optical properties predicted by these biooptical relationships and compared with published in situ data. It was found that the simulated R rs was overestimated for turbid water. To achieve optical closure, bio-optical relationships for absorption and scattering coefficients for suspended particulate matter were adjusted. Furthermore, the results show that the Fournier and Forand phase functions obtained from the adjusted relationships perform better than the Petzold phase function. Therefore, before bio-optical relationships are used for a local sea area, the optical closure should be examined.

  8. Bio-Optics of the Chesapeake Bay from Measurements and Radiative Transfer Calculations

    NASA Technical Reports Server (NTRS)

    Tzortziou, Maria; Herman, Jay R.; Gallegos, Charles L.; Neale, Patrick J.; Subramaniam, Ajit; Harding, Lawrence W., Jr.; Ahmad, Ziauddin

    2005-01-01

    We combined detailed bio-optical measurements and radiative transfer (RT) modeling to perform an optical closure experiment for optically complex and biologically productive Chesapeake Bay waters. We used this experiment to evaluate certain assumptions commonly used when modeling bio-optical processes, and to investigate the relative importance of several optical characteristics needed to accurately model and interpret remote sensing ocean-color observations in these Case 2 waters. Direct measurements were made of the magnitude, variability, and spectral characteristics of backscattering and absorption that are critical for accurate parameterizations in satellite bio-optical algorithms and underwater RT simulations. We found that the ratio of backscattering to total scattering in the mid-mesohaline Chesapeake Bay varied considerably depending on particulate loading, distance from land, and mixing processes, and had an average value of 0.0128 at 530 nm. Incorporating information on the magnitude, variability, and spectral characteristics of particulate backscattering into the RT model, rather than using a volume scattering function commonly assumed for turbid waters, was critical to obtaining agreement between RT calculations and measured radiometric quantities. In situ measurements of absorption coefficients need to be corrected for systematic overestimation due to scattering errors, and this correction commonly employs the assumption that absorption by particulate matter at near infrared wavelengths is zero.

  9. The Global Geodetic Infrastructure for Accurate Monitoring of Earth Systems

    NASA Astrophysics Data System (ADS)

    Weston, Neil; Blackwell, Juliana; Wang, Yan; Willis, Zdenka

    2014-05-01

    The National Geodetic Survey (NGS) and the Integrated Ocean Observing System (IOOS), two Program Offices within the National Ocean Service, NOAA, routinely collect, analyze and disseminate observations and products from several of the 17 critical systems identified by the U.S. Group on Earth Observations. Gravity, sea level monitoring, coastal zone and ecosystem management, geo-hazards and deformation monitoring and ocean surface vector winds are the primary Earth systems that have active research and operational programs in NGS and IOOS. These Earth systems collect terrestrial data but most rely heavily on satellite-based sensors for analyzing impacts and monitoring global change. One fundamental component necessary for monitoring via satellites is having a stable, global geodetic infrastructure where an accurate reference frame is essential for consistent data collection and geo-referencing. This contribution will focus primarily on system monitoring, coastal zone management and global reference frames and how the scientific contributions from NGS and IOOS continue to advance our understanding of the Earth and the Global Geodetic Observing System.

  10. Bio-optical properties of oceanic waters: A reappraisal

    NASA Astrophysics Data System (ADS)

    Morel, André; Maritorena, StéPhane

    2001-04-01

    The apparent optical properties (AOPs) of oceanic case 1 waters were previously analyzed [Morel, 1988] and statistically related to the chlorophyll concentration ([Chl]) used as a global index describing the trophic conditions of water bodies. From these empirical relationships a bio-optical model of the upper layer was developed. With objectives and structure similar to those of the previous study the present reappraisal utilizes AOPs determined during recent Joint Global Ocean Flux Study cruises, namely, spectral attenuation for downward irradiance Kd(λ) and irradiance reflectance R(λ). This revision also benefits from improved knowledge of inherent optical properties (IOPs), namely, pure water absorption coefficients and particle scattering and absorption coefficients, and from better pigment quantification (via a systematic use of high-performance liquid chromatography). Nonlinear trends, already observed between optical properties and algal biomass, are fully confirmed, yet with numerical differences. The previous Kd(λ) model, and subsequently the R(λ) model, is modified to account for these new relationships. The R(λ) values predicted as a function of [Chl] and the predicted ratios of reflectances at two wavelengths, which are commonly used in ocean color algorithms, compare well with field values (not used when developing the reflectance model). This good agreement means that semianalytical ocean color algorithms can be successfully applied to satellite data. Going further into purely analytical approaches, ideally based on radiative transfer computations combined with a suite of relationships between the IOPs and [Chl], remains presently problematic, especially because of the insufficient knowledge of the phase function and backscattering efficiency of oceanic particles.

  11. Bio-Optical Measurement and Modeling of the California Current and Polar Oceans

    NASA Technical Reports Server (NTRS)

    Mitchell, B. Greg; Fargion, Giulietta S. (Technical Monitor)

    2001-01-01

    The principal goals of our research are to validate standard or experimental products through detailed bio-optical and biogeochemical measurements, and to combine ocean optical observations with advanced radiative transfer modeling to contribute to satellite vicarious radiometric calibration and advanced algorithm development. To achieve our goals requires continued efforts to execute complex field programs globally, as well as development of advanced ocean optical measurement protocols. We completed a comprehensive set of ocean optical observations in the California Current, Southern Ocean, Indian Ocean requiring a large commitment to instrument calibration, measurement protocols, data processing and data merger. We augmented separately funded projects of our own, as well as others, to acquire ill situ data sets we have collected on various global cruises supported by separate grants or contracts. In collaboration with major oceanographic ship-based observation programs funded by various agencies (CalCOFI, US JGOFS, NOAA AMLR, INDOEX and Japan/East Sea) our SIMBIOS effort has resulted in data from diverse bio-optical provinces. For these global deployments we generate a high-quality, methodologically consistent, data set encompassing a wide-range of oceanic conditions. Global data collected in recent years have been integrated with our on-going CalCOFI database and have been used to evaluate SeaWiFS algorithms and to carry out validation studies. The combined database we have assembled now comprises more than 700 stations and includes observations for the clearest oligotrophic waters, highly eutrophic blooms, red-tides and coastal case 2 conditions. The data has been used to validate water-leaving radiance estimated with SeaWiFS as well as bio-optical algorithms for chlorophyll pigments. The comprehensive data is utilized for development of experimental algorithms (e.g. high-low latitude pigment transition, phytoplankton absorption, and cDOM). During this period

  12. The SeaWiFS Bio-Optical Archive and Storage System (SeaBASS): Current Architecture and Implementation

    NASA Technical Reports Server (NTRS)

    Werdell, P. Jeremy; Fargion, Giulietta S. (Editor); McClain, Charles R. (Editor); Bailey, Sean W.

    2002-01-01

    Satellite ocean color missions require an abundance of high-quality in situ measurements for bio-optical and atmospheric algorithm development and post-launch product validation and sensor calibration. To facilitate the assembly of a global data set, the NASA Sea-viewing Wide Field-of-view (SeaWiFS) Project developed the Seafaring Bio-optical Archive and Storage System (SeaBASS), a local repository for in situ data regularly used in their scientific analyses. The system has since been expanded to contain data sets collected by the NASA Sensor Intercalibration and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project, as part of NASA Research Announcements NRA-96-MTPE-04 and NRA-99-OES-99. SeaBASS is a well moderated and documented hive for bio-optical data with a simple, secure mechanism for locating and extracting data based on user inputs. Its holdings are available to the general public with the exception of the most recently collected data sets. Extensive quality assurance protocols, comprehensive data and system documentation, and the continuation of an archive and relational database management system (RDBMS) suitable for bio-optical data all contribute to the continued success of SeaBASS. This document provides an overview of the current operational SeaBASS system.

  13. Bio-Optical Measurement and Modeling of the California Current and Polar Oceans. Chapter 13

    NASA Technical Reports Server (NTRS)

    Mitchell, B. Greg

    2001-01-01

    This Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) project contract supports in situ ocean optical observations in the California Current, Southern Ocean, Indian Ocean as well as merger of other in situ data sets we have collected on various global cruises supported by separate grants or contracts. The principal goals of our research are to validate standard or experimental products through detailed bio-optical and biogeochemical measurements, and to combine ocean optical observations with advanced radiative transfer modeling to contribute to satellite vicarious radiometric calibration and advanced algorithm development. In collaboration with major oceanographic ship-based observation programs funded by various agencies (CalCOFI, US JGOFS, NOAA AMLR, INDOEX and Japan/East Sea) our SIMBIOS effort has resulted in data from diverse bio-optical provinces. For these global deployments we generate a high-quality, methodologically consistent, data set encompassing a wide-range of oceanic conditions. Global data collected in recent years have been integrated with our on-going CalCOFI database and have been used to evaluate Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) algorithms and to carry out validation studies. The combined database we have assembled now comprises more than 700 stations and includes observations for the clearest oligotrophic waters, highly eutrophic blooms, red-tides and coastal case two conditions. The data has been used to validate water-leaving radiance estimated with SeaWiFS as well as bio optical algorithms for chlorophyll pigments. The comprehensive data is utilized for development of experimental algorithms (e.g., high-low latitude pigment transition, phytoplankton absorption, and cDOM).

  14. A new bio-optical algorithm for the remote sensing of algal blooms in complex ocean waters

    NASA Astrophysics Data System (ADS)

    Shanmugam, Palanisamy

    2011-04-01

    A new bio-optical algorithm has been developed to provide accurate assessments of chlorophyll a (Chl a) concentration for detection and mapping of algal blooms from satellite data in optically complex waters, where the presence of suspended sediments and dissolved substances can interfere with phytoplankton signal and thus confound conventional band ratio algorithms. A global data set of concurrent measurements of pigment concentration and radiometric reflectance was compiled and used to develop this algorithm that uses the normalized water-leaving radiance ratios along with an algal bloom index (ABI) between three visible bands to determine Chl a concentrations. The algorithm is derived using Sea-viewing Wide Field-of-view Sensor bands, and it is subsequently tuned to be applicable to Moderate Resolution Imaging Spectroradiometer (MODIS)/Aqua data. When compared with large in situ data sets and satellite matchups in a variety of coastal and ocean waters the present algorithm makes good retrievals of the Chl a concentration and shows statistically significant improvement over current global algorithms (e.g., OC3 and OC4v4). An examination of the performance of these algorithms on several MODIS/Aqua images in complex waters of the Arabian Sea and west Florida shelf shows that the new algorithm provides a better means for detecting and differentiating algal blooms from other turbid features, whereas the OC3 algorithm has significant errors although yielding relatively consistent results in clear waters. These findings imply that, provided that an accurate atmospheric correction scheme is available to deal with complex waters, the current MODIS/Aqua, MERIS and OCM data could be extensively used for quantitative and operational monitoring of algal blooms in various regional and global waters.

  15. Introduction to the bio-optics: design and application

    PubMed Central

    Tkaczyk, Tomasz; Xu, Chris

    2015-01-01

    The “Bio-Optics: Design and Application” symposium, held on April 12–15, 2015, in Vancouver, BC, was an important step in a continuous journey to closely connect technological design advancement and biomedical applications. The symposium presented a broad range of innovations in diagnostic devices, endoscopy, optical microscopy, optical coherence tomography, multi-modal imaging, and highlighted specific applications including cancer diagnostics, detection of infectious disease and point of care, as well as microsurgery treatment. PMID:26713203

  16. Bio-Optical Properties of the Arabian Sea as Determined by In-Situ and SeaWifs Data

    NASA Technical Reports Server (NTRS)

    Trees, Charles C.

    1998-01-01

    The overall objective of this work was to characterize optical and fluorescence properties in the euphotic zone during two British Ocean Flux Study (BOFS) Arabian Sea cruises. This was later expanded in 1995 to include three U.S. Joint Global Ocean Flux Study (JGOFS) Arabian Sea Cruises. The region was to be divided into one or more "bio-optical provinces", within each of which a single set of regression models was to be developed to relate the vertical distribution of irradiance attenuation and normalized fluorescence (SF and NF) to remote sensing reflectance and diffuse attenuation coefficient [K(490)]. The working hypothesis was that over relatively large spatial and temporal scales, the vertical profiles of bio-optical properties were predictable.

  17. Accurate Realization of GPS Vertical Global Reference Frame

    NASA Technical Reports Server (NTRS)

    Elosegui, Pedro

    2004-01-01

    The few millimeter per year level accuracy of radial global velocity estimates with the Global Positioning System (GPS) is at least an order of magnitude poorer than the accuracy of horizontal global motions. An improvement in the accuracy of radial global velocities would have a very positive impact on a number of geophysical studies of current general interest such as global sea-level and climate change, coastal hazards, glacial isostatic adjustment, atmospheric and oceanic loading, glaciology and ice mass variability, tectonic deformation and volcanic inflation, and geoid variability. The goal of this project is to improve our current understanding of GPS error sources associated with estimates of radial velocities at global scales. GPS error sources relevant to this project can be classified in two broad categories: (1) those related to the analysis of the GPS phase observable, and (2) those related to the combination of the positions and velocities of a set of globally distributed stations as determined from the analysis of GPS data important aspect in the first category include the effect on vertical rate estimates due to standard analysis choices, such as orbit modeling, network geometry, ambiguity resolution, as well as errors in models (or simply the lack of models) for clocks, multipath, phase-center variations, atmosphere, and solid-Earth tides. The second category includes the possible methods of combining and defining terrestrial reference flames for determining vertical velocities in a global scale. The latter has been the subject of our research activities during this reporting period.

  18. Accurate Realization of GPS Vertical Global Reference Frame

    NASA Technical Reports Server (NTRS)

    Elosegui, Pedro

    2005-01-01

    The goal of this project is to improve our current understanding of GPS error sources associated with estimates of radial velocities at global scales. An improvement in the accuracy of radial global velocities would have a very positive impact on a large number of geophysical studies of current general interest such as global sea-level and climate change, coastal hazards, glacial isostatic adjustment, atmospheric and oceanic loading, glaciology and ice mass variability, tectonic deformation and volcanic inflation, and geoid variability. A set of GPS error sources relevant to this project are those related to the combination of the positions and velocities of a set of globally distributed stations as determined &om the analysis of GPS data, including possible methods of combining and defining terrestrial reference frames. This is were our research activities during this reporting period have concentrated. During this reporting period, we have researched two topics: (1) The effect of errors on the GPS satellite antenna models (or lack thereof) on global GPS vertical position and velocity estimates; (2) The effect of reference W e definition and practice on estimates of the geocenter variations.

  19. The Bermuda Bio-Optics Program (BBOP). Chapter 16

    NASA Technical Reports Server (NTRS)

    Siegel, David A.

    2001-01-01

    The Bermuda Bio-Optics Project (BBOP) is a collaborative effort between the Institute for Computational Earth System Science (ICESS) at the University of California at Santa Barbara (UCSB) and the Bermuda Biological Station for Research (BBSR). This research program is designed to characterize light availability and utilization in the Sargasso Sea, and to provide an optical link by which biogeochemical observations may be used to evaluate bio-optical models for pigment concentration, primary production, and sinking particle fluxes from satellite-based ocean color sensors. The BBOP time-series was initiated in 1992, and is carried out in conjunction with the US JGOFS Bermuda Atlantic Time-series Study (BATS) at the Bermuda Biological Station for Research. The BATS program itself has been observing biogeochemical processes (primary productivity, particle flux at and elemental cycles) in the mesotrophic waters of the Sargasso Sea since 1988. Closely affiliated with BBOP and BATS is a separate NASA-funded study of the spatial variability of biogeochemical processes in the Sargasso Sea using high-resolution Advanced Very High Resolution Radiometer (AVHRR) and Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) data collected at Bermuda. The collaboration between BATS and BBOP measurements has resulted in a unique data set that addresses not only the SIMBIOS goals but also the broader issues of important factors controlling the carbon cycle.

  20. Accurate aircraft wind measurements using the global positioning system (GPS)

    SciTech Connect

    Dobosy, R.J.; Crawford, T.L., McMillen, R.T., Dumas, E.J.

    1996-11-01

    High accuracy measurements of the spatial distribution of wind speed are required in the study of turbulent exchange between the atmosphere and the earth. The use of a differential global positioning system (GPS) to determine the sensor velocity vector component of wind speed is discussed in this paper. The results of noise and rocking testing are summarized, and fluxes obtained from the GPS-based methods are compared to those measured from systems on towers and airplanes. The GPS-based methods provided usable measurements that compared well with tower and aircraft data at a significantly lower cost. 21 refs., 1 fig., 2 tabs.

  1. Retrieval of near-surface bio-optical properties of the Arabian Sea from remotely sensed ocean colour data

    NASA Astrophysics Data System (ADS)

    Pinkerton, M. H.; Trees, C. C.; Aiken, J.; Bale, A. J.; Moore, G. F.; Barlow, R. G.; Cummings, D. G.

    1999-03-01

    The use of CZCS-type band-ratio algorithms to estimate the diffuse attenuation coefficient, percentage light depths, and near-surface optically weighted phytoplankton pigment concentrations from remotely sensed ocean colour data was investigated on two cruises in the Arabian Sea and Gulf of Oman during autumn and winter 1994. The variations of upwelling radiance and downwelling irradiance with depth were measured along with phytoplankton pigment concentrations by HPLC. A spectroradiometer was used on the second cruise to investigate the feasibility of measuring water-leaving radiance from above the sea surface. Retrieval of the diffuse downwelling attenuation coefficient at 490 nm was accurate to within 22% of the actual value across both cruises. There was also a robust relationship between the diffuse attenuation coefficient and the 10, 1 and 0.1% light depths. Above-surface estimates of water-leaving radiance agreed with SeaWiFS-standard estimates to within 10% between 443 and 555 nm. The global 443 : 555 band-ratio algorithms of Aiken et al. [NASA Tech. Memo 104566, Vol. 29, SeaWiFS Technical Report Series, 34 pp] estimated near-surface chlorophyll- a and fluorometric pigment concentrations with mean absolute errors of less than 35% of the actual values (which were all less than 2.0 mg m -3). The performance of algorithms based on the 490 : 555 ratio was poorer. The estimates given by the algorithms were generally higher than the measured pigment concentrations and the variance of the accuracy of the estimates was high. There appears to be no significant change in the performance of the algorithms between cruises (approximately 2 1/2 months apart in time). There is no evidence that the Gulf of Oman should be treated as a separate bio-optical province to the Arabian Sea/Omani shelf area for the purpose of the retrieval of near-surface pigment concentrations from ocean colour observations.

  2. Bio-optical properties of Porsnagerfjorden (Norway) waters based on data collected in 2014 and 2015

    NASA Astrophysics Data System (ADS)

    Białogrodzka, Jagoda; Stramska, Małgorzata; Burska, Dorota; Ficek, Dariusz; Stoń-Egiert, Joanna; Winogradow, Aleksandra

    2016-04-01

    Oceanographic data collected in the Arctic are valuable in view of the role of this region in the studies on global climate change and the fact that historically the number of in situ measurements is relatively low. Porsangerfjorden, Norway, is an example of oceanic basin with case 2 water according to the optical classification. Optical data from coastal seas are difficult in interpretation because the concentrations of optically important components can be high, variable, and not covarying with each other. Porsanger Fjord can be divided into three basins: inner, middle and outer, where physical and bio-optical properties of water masses differ. We collected optical data and water samples for phytoplankton pigments, dissolved organic matter, particulate (POC) and dissolved (DOC) organic carbon, and particulate inorganic carbon (PIC) during our two summer expeditions in 2014 and 2015. In this presentation we focus on data collected with WETLabs' ac-9 and ac-s spectrophotometers and ECO-Triplet and ECO-Triplet-w fluorometers. Concurrently with in situ optical measurements water samples were collected in situ and soon afterwards they were filtered in the laboratory at the station, stored and transported for further processing in Poland. Our analysis includes 146 of in situ measurements and discrete water samples: 62 of POC, 52 of PIC, 33 of DOC, 68 of dissolved organic matter and 89 of phytoplankton pigments. During our analysis we compare chlorophyll (Chl_a), dissolved organic matter (CDOM) and carbon concentrations with in situ collected inherent optical properties of sea water to find empirical proxies allowing to estimate various water component concentrations from optical data. Application of these proxies to available bio-optical data allowed us to derive spatial distribution of these water constituents and their variability. This work was funded by the Norway Grants (NCBR contract No. 201985, project NORDFLUX).

  3. Airborne bio-optics survey of the Galapagos Islands margins

    NASA Astrophysics Data System (ADS)

    Hoge, Frank E.; Wayne Wright, C.; Swift, Robert N.; Yungel, James K.; Berry, Richard E.; Mitchell, Richard

    Aircraft and ship surveys of the Galapagos Islands were conducted to address the hypothesized influence of "island-leached" iron upon phytoplankton production. This paper describes the airborne survey of the Galapagos Islands that composed the second phase of a two-part study of the influence of iron on phytoplankton production in high-nutrient/low-chlorophyll (HNLC) regions. A single bio-optics airborne survey transect along 92°W from 1°N to 2°S was executed on 25 October 1993 in order to provide initial reconnaissance spatial and temporal sampling of the oceanic region west of the Galapagos Islands. A more extensive airborne bio-optics survey of the entire Galapagos Islands region was conducted on 3 November 1993. This expanded flight survey was made along all the ship cruise tracks of the R.V. Columbus Iselin originally planned for 15-27 November 1993. Analysis of the surface-layer airborne laser-induced and water-Raman normalized chlorophyll, phycoerythrin, and chromophoric dissolved organic matter (CDOM) fluorescence, SST, and AXBT (airborne expendable bathythermograph) data suggest that: (1) the regional distribution of phytoplankton and dissolved organic matter is dominated by the strong east-west thermal boundary located both east and west of the Galapagos Islands; (2) the source for the elevated phytoplankton patches west of the Galapagos Islands is from upwelling rather than aeolian sources or from the westward drift of iron and nutrients leached from the islands themselves or offshore shallow bottom sources; (3) the introduction of subsurface water to the surface may occur in episodic events rather than as a steady-state process; and (4) the chronic high chlorophyll west of the Galapagos Islands noted in processed Coastal Zone Color Scanner (CZCS) images may be due, at least in part, to the presence of elevated levels of chromophoric dissolved organic matter (CDOM) absorption.

  4. Bio-optical profiling floats as new observational tools for biogeochemical and ecosystem studies: Potential synergies with ocean color remote sensing

    SciTech Connect

    Claustre, H.; Bishop, J.; Boss, E.; Bernard, S.; Berthon, J.-F.; Coatanoan, C.; Johnson, K.; Lotiker, A.; Ulloa, O.; Perry, M.J.; D'Ortenzio, F.; D'andon, O.H.F.; Uitz, J.

    2009-10-01

    Profiling floats now represent a mature technology. In parallel with their emergence, the field of miniature, low power bio-optical and biogeochemical sensors is rapidly evolving. Over recent years, the bio-geochemical and bio-optical community has begun to benefit from the increase in observational capacities by developing profiling floats that allow the measurement of key biooptical variables and subsequent products of biogeochemical and ecosystem relevance like Chlorophyll a (Chla), optical backscattering or attenuation coefficients which are proxies of Particulate Organic Carbon (POC), Colored Dissolved Organic Matter (CDOM). Thanks to recent algorithmic improvements, new bio-optical variables such as backscattering coefficient or absorption by CDOM, at present can also be extracted from space observations of ocean color. In the future, an intensification of in situ measurements by bio-optical profiling floats would permit the elaboration of unique 3D/4D bio-optical climatologies, linking surface (remotely detected) properties to their vertical distribution (measured by autonomous platforms), with which key questions in the role of the ocean in climate could be addressed. In this context, the objective of the IOCCG (International Ocean Color Coordinating Group) BIO-Argo working group is to elaborate recommendations in view of a future use of bio-optical profiling floats as part of a network that would include a global array that could be 'Argo-relevant', and specific arrays that would have more focused objectives or regional targets. The overall network, realizing true multi-scale sustained observations of global marine biogeochemistry and biooptics, should satisfy the requirements for validation of ocean color remote sensing as well as the needs of a wider community investigating the impact of global change on biogeochemical cycles and ecosystems. Regarding the global profiling float array, the recommendation is that Chla as well as POC should be the key

  5. Decadal trends and common dynamics of the bio-optical and thermal characteristics of the African Great Lakes.

    PubMed

    Loiselle, Steven; Cózar, Andrés; Adgo, Enyew; Ballatore, Thomas; Chavula, Geoffrey; Descy, Jean Pierre; Harper, David M; Kansiime, Frank; Kimirei, Ismael; Langenberg, Victor; Ma, Ronghua; Sarmento, Hugo; Odada, Eric

    2014-01-01

    The Great Lakes of East Africa are among the world's most important freshwater ecosystems. Despite their importance in providing vital resources and ecosystem services, the impact of regional and global environmental drivers on this lacustrine system remains only partially understood. We make a systematic comparison of the dynamics of the bio-optical and thermal properties of thirteen of the largest African lakes between 2002 and 2011. Lake surface temperatures had a positive trend in all Great Lakes outside the latitude of 0° to 8° south, while the dynamics of those lakes within this latitude range were highly sensitive to global inter-annual climate drivers (i.e. El Niño Southern Oscillation). Lake surface temperature dynamics in nearly all lakes were found to be sensitive to the latitudinal position of the Inter Tropical Convergence Zone. Phytoplankton dynamics varied considerably between lakes, with increasing and decreasing trends. Intra-lake differences in both surface temperature and phytoplankton dynamics occurred for many of the larger lakes. This inter-comparison of bio-optical and thermal dynamics provides new insights into the response of these ecosystems to global and regional drivers. PMID:24699528

  6. Bio-optical characteristics along the Straits of Magallanes

    NASA Astrophysics Data System (ADS)

    Lutz, Vivian; Frouin, Robert; Negri, Rubén; Silva, Ricardo; Pompeu, Mayza; Rudorff, Natalia; Cabral, Anderson; Dogliotti, Ana; Martinez, Gustavo

    2016-05-01

    The Straits of Magallanes at the tip of South America connects the Atlantic and Pacific Oceans. The variability in the absorption characteristics by phytoplankton (aph(440)), non-pigmented particles, NPP (aNPP(440)), and chromophoric dissolved organic matter, CDOM (ay(440)), measured along the Straits in late summer 2011 (R/V Melville MV1102 cruise), was analyzed. Satellite-derived monthly PAR data showed that at the time of the cruise the western sector was exposed to a low-light environment (~ 16 mol quanta m-2d-1) while the eastern sector received higher irradiance (~ 28 mol quanta m-2d-1). In the Patagonian Shelf total absorption was dominated by phytoplankton (up to 76%; aph(440)=0.265 m-1), while in the Atlantic Sector of the Straits, the major contributor was NPP (up to 42%; aNPP(440)=0.138 m-1), and in the Pacific Sector of the Straits CDOM contributed up to 80% of the total absorption (ay(440)=0.232 m-1). These changes could be related in part to the input of fresh water from glacier melting and rain in the Pacific Sector (ay(440) vs salinity rs=-0.98). The carbon biomass (C) was composed in its majority by pico-phytoplankton and secondly by nano-phytoplankton, with exception of the Atlantic Sector where the micro-phytoplankton dominated. Carbon to chlorophyll-a ratios (C:Chla) were very low throughout the Straits (average of ~ 6) because of photoacclimation to the extremely low light. Complementary pigments data obtained in spring 2003 by the BEAGLE expedition indicated the predominance of diatoms all along the Straits, but the bio-optical trend resembled the one found in late summer 2011, i.e., NPP dominated the absorption in the well mixed Atlantic Sector, phytoplankton in the Middle Sector, and CDOM in the Pacific Sector. These results emphasize that underwater light is the major factor affecting phytoplankton growth and physiology, and that prevalent physical and geochemical conditions play an important role regulating the bio-optical properties in

  7. First Autonomous Bio-Optical Profiling Float in the Gulf of Mexico Reveals Dynamic Biogeochemistry in Deep Waters

    PubMed Central

    Green, Rebecca E.; Bower, Amy S.; Lugo-Fernández, Alexis

    2014-01-01

    Profiling floats equipped with bio-optical sensors well complement ship-based and satellite ocean color measurements by providing highly-resolved time-series data on the vertical structure of biogeochemical processes in oceanic waters. This is the first study to employ an autonomous profiling (APEX) float in the Gulf of Mexico for measuring spatiotemporal variability in bio-optics and hydrography. During the 17-month deployment (July 2011 to December 2012), the float mission collected profiles of temperature, salinity, chlorophyll fluorescence, particulate backscattering (bbp), and colored dissolved organic matter (CDOM) fluorescence from the ocean surface to a depth of 1,500 m. Biogeochemical variability was characterized by distinct depth trends and local “hot spots”, including impacts from mesoscale processes associated with each of the water masses sampled, from ambient deep waters over the Florida Plain, into the Loop Current, up the Florida Canyon, and eventually into the Florida Straits. A deep chlorophyll maximum (DCM) occurred between 30 and 120 m, with the DCM depth significantly related to the unique density layer ρ = 1023.6 (R2 = 0.62). Particulate backscattering, bbp, demonstrated multiple peaks throughout the water column, including from phytoplankton, deep scattering layers, and resuspension. The bio-optical relationship developed between bbp and chlorophyll (R2 = 0.49) was compared to a global relationship and could significantly improve regional ocean-color algorithms. Photooxidation and autochthonous production contributed to CDOM distributions in the upper water column, whereas in deep water, CDOM behaved as a semi-conservative tracer of water masses, demonstrating a tight relationship with density (R2 = 0.87). In the wake of the Deepwater Horizon oil spill, this research lends support to the use of autonomous drifting profilers as a powerful tool for consideration in the design of an expanded and integrated observing network

  8. First autonomous bio-optical profiling float in the Gulf of Mexico reveals dynamic biogeochemistry in deep waters.

    PubMed

    Green, Rebecca E; Bower, Amy S; Lugo-Fernández, Alexis

    2014-01-01

    Profiling floats equipped with bio-optical sensors well complement ship-based and satellite ocean color measurements by providing highly-resolved time-series data on the vertical structure of biogeochemical processes in oceanic waters. This is the first study to employ an autonomous profiling (APEX) float in the Gulf of Mexico for measuring spatiotemporal variability in bio-optics and hydrography. During the 17-month deployment (July 2011 to December 2012), the float mission collected profiles of temperature, salinity, chlorophyll fluorescence, particulate backscattering (bbp), and colored dissolved organic matter (CDOM) fluorescence from the ocean surface to a depth of 1,500 m. Biogeochemical variability was characterized by distinct depth trends and local "hot spots", including impacts from mesoscale processes associated with each of the water masses sampled, from ambient deep waters over the Florida Plain, into the Loop Current, up the Florida Canyon, and eventually into the Florida Straits. A deep chlorophyll maximum (DCM) occurred between 30 and 120 m, with the DCM depth significantly related to the unique density layer ρ = 1023.6 (R2 = 0.62). Particulate backscattering, bbp, demonstrated multiple peaks throughout the water column, including from phytoplankton, deep scattering layers, and resuspension. The bio-optical relationship developed between bbp and chlorophyll (R2 = 0.49) was compared to a global relationship and could significantly improve regional ocean-color algorithms. Photooxidation and autochthonous production contributed to CDOM distributions in the upper water column, whereas in deep water, CDOM behaved as a semi-conservative tracer of water masses, demonstrating a tight relationship with density (R2 = 0.87). In the wake of the Deepwater Horizon oil spill, this research lends support to the use of autonomous drifting profilers as a powerful tool for consideration in the design of an expanded and integrated observing network for

  9. Bio-Optical Measurement and Modeling of the California Current and Southern Oceans

    NASA Technical Reports Server (NTRS)

    Mitchell, B. Gregg; Mitchell, B. Greg

    2003-01-01

    The SIMBIOS project's principal goals are to validate standard or experimental ocean color products through detailed bio-optical and biogeochemical measurements, and to combine Ocean optical observations with modeling to contribute to satellite vicarious radiometric calibration and algorithm development.

  10. Bio-Optical Measurements at Ocean Boundaries in Support of SIMBIOS. Chapter 7

    NASA Technical Reports Server (NTRS)

    Chavez, Francisco P.; Strutton, Peter G.; Schlining, Brian M.

    2001-01-01

    The equatorial Pacific is a major component of global biogeochemical cycles, due to upwelling that occurs from the coast of South America to beyond 180 deg. This upwelling has significant implications for global CO2 fluxes, as well as primary and secondary production. In addition, this region of the world's oceans represents a large oceanic province over which validation data for Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) are necessary. This project consists of a mooring program and supporting cruise-based measurements aimed at quantifying the spectrum of biological and chemical variability in the equatorial Pacific and obtaining validation data for SeaWiFS. The project has the following general objectives: (1) to understand the relationships between physical forcing, primary production, nutrient supply and the exchange of carbon dioxide between ocean and atmosphere in the equatorial Pacific; (2) to describe the biological and chemical responses to climate and ocean variability; (3) to describe the spatial, seasonal and inter-annual variability in near surface plant pigments, primary production, carbon dioxide and nutrient distributions; and (4) to obtain near real-time bio-optical measurements for validation of SeaWiFS and subsequent ocean color sensors.

  11. Bio-optical water quality dynamics observed from MERIS in Pensacola Bay, Florida

    NASA Astrophysics Data System (ADS)

    Le, Chengfeng; Lehrter, John C.; Schaeffer, Blake A.; Hu, Chuanmin; Murrell, Michael C.; Hagy, James D.; Greene, Richard M.; Beck, Marcus

    2016-05-01

    Observed bio-optical water quality data collected from 2009 to 2011 in Pensacola Bay, Florida were used to develop empirical remote sensing retrieval algorithms for chlorophyll a (Chla), colored dissolved organic matter (CDOM), and suspended particulate matter (SPM). Time-series of the three bio-optical water quality variables were generated from MEdium Resolution Imaging Spectrometer (MERIS) observations from 2003 to 2011. Bio-optical water quality in this estuary exhibited spatial and temporal variations that were correlated to river discharge and wind. Both annual mean and monthly mean bio-optical water quality variables were positively correlated to river discharge. Monthly mean bio-optical water quality variables were also positively correlated to wind speed and wind density (defined by the number of days with daily mean wind speed > 3 m s-1 in a month) over this estuary. These results indicate that bio-optical water quality dynamics in this estuary are vulnerable to changes in river discharge and river constituent loads and local weather conditions such as winter storms and hurricanes.

  12. Development of a regional bio-optical model for water quality assessment in the US Virgin Islands

    NASA Astrophysics Data System (ADS)

    Kerrigan, Kristi Lisa

    Previous research in the US Virgin Islands (USVI) has demonstrated that land-based sources of pollution associated with watershed development and climate change are local and global factors causing coral reef degradation. A good indicator that can be used to assess stress on these environments is the water quality. Conventional assessment methods based on in situ measurements are timely and costly. Satellite remote sensing techniques offer better spatial coverage and temporal resolution to accurately characterize the dynamic nature of water quality parameters by applying bio-optical models. Chlorophyll-a, suspended sediments (TSM), and colored-dissolved organic matter are color-producing agents (CPAs) that define the water quality and can be measured remotely. However, the interference of multiple optically active constituents that characterize the water column as well as reflectance from the bottom poses a challenge in shallow coastal environments in USVI. In this study, field and laboratory based data were collected from sites on St. Thomas and St. John to characterize the CPAs and bottom reflectance of substrates. Results indicate that the optical properties of these waters are a function of multiple CPAs with chlorophyll-a values ranging from 0.10 to 2.35 microg/L and TSM values from 8.97 to 15.7 mg/L. These data were combined with in situ hyperspectral radiometric and Landsat OLI satellite data to develop a regionally tiered model that can predict CPA concentrations using traditional band ratio and multivariate approaches. Band ratio models for the hyperspectral dataset (R2 = 0.35; RMSE = 0.10 microg/L) and Landsat OLI dataset (R2 = 0.35; RMSE = 0.12 microg/L) indicated promising accuracy. However, a stronger model was developed using a multivariate, partial least squares regression to identify wavelengths that are more sensitive to chlorophyll-a (R2 = 0.62, RMSE = 0.08 microg/L) and TSM (R2 = 0.55). This approach takes advantage of the full spectrum of

  13. [Algorithm for estimating chlorophyll-a concentration in case II water body based on bio-optical model].

    PubMed

    Yang, Wei; Chen, Jin; Mausushita, Bunki

    2009-01-01

    In the present study, a novel retrieval method for estimating chlorophyll-a concentration in case II waters based on bio-optical model was proposed and was tested with the data measured in the laboratory. A series of reflectance spectra, with which the concentration of each sample constituent (for example chlorophyll-a, NPSS etc.) was obtained from accurate experiments, were used to calculate the absorption and backscattering coefficients of the constituents of the case II waters. Then non-negative least square method was applied to calculate the concentration of chlorophyll-a and non-phytoplankton suspended sediments (NPSS). Green algae was firstly collected from the Kasumigaura lake in Japan and then cultured in the laboratory. The reflectance spectra of waters with different amounts of phytoplankton and NPSS were measured in the dark room using FieldSpec Pro VNIR (Analytical Spectral Devises Inc. , Boulder, CO, USA). In order to validate whether this method can be applied in multispectral data (for example Landsat TM), the spectra measured in the laboratory were resampled with Landsat TM bands 1, 2, 3 and 4. Different combinations of TM bands were compared to derive the most appropriate wavelength for detecting chlorophyll-a in case II water for green algae. The results indicated that the combination of TM bands 2, 3 and 4 achieved much better accuracy than other combinations, and the estimated concentration of chlorophyll-a was significantly more accurate than empirical methods. It is expected that this method can be directly applied to the real remotely sensed image because it is based on bio-optical model. PMID:19385201

  14. The Scientific and Societal Need for Accurate Global Remote Sensing of Marine Suspended Sediments

    NASA Technical Reports Server (NTRS)

    Acker, James G.

    2006-01-01

    Population pressure, commercial development, and climate change are expected to cause continuing alteration of the vital oceanic coastal zone environment. These pressures will influence both the geology and biology of the littoral, nearshore, and continental shelf regions. A pressing need for global observation of coastal change processes is an accurate remotely-sensed data product for marine suspended sediments. The concentration, delivery, transport, and deposition of sediments is strongly relevant to coastal primary production, inland and coastal hydrology, coastal erosion, and loss of fragile wetland and island habitats. Sediment transport and deposition is also related to anthropogenic activities including agriculture, fisheries, aquaculture, harbor and port commerce, and military operations. Because accurate estimation of marine suspended sediment concentrations requires advanced ocean optical analysis, a focused collaborative program of algorithm development and assessment is recommended, following the successful experience of data refinement for remotely-sensed global ocean chlorophyll concentrations.

  15. BIO-OPTICAL CHARACTERIZATION OF THE DINOFLAGELLATE GYMNODINIUM BREVE AND THE DIATOM THALASSIOSIRA WEISSFLOGII IN OUTDOOR TANKS

    EPA Science Inventory

    The bio-optical signatures of harmful algal blooms can be used to define ocean color satellite algorithms. We characterized the bio-optical properties of nutrient-replete cultures of the red tide dinoflagellate Gymnodinium breve and the diatom Thalassiosira weissflogii. We cultur...

  16. Evaluation of bio-optical algorithms to remotely sense marine primary production from space

    NASA Technical Reports Server (NTRS)

    Berthelot, Beatrice; Deschamps, Pierre-Yves

    1994-01-01

    In situ bio-optical measurements from several oceanographic campaigns were analyzed to derive a direct relationship between water column primary production P (sub t) ocean color as expressed by the ratio of reflectances R (sub 1) at 440 nm and R (sub 3) at 550 nm and photosynthetically available radiation (PAR). The study is restricted to the Morel case I waters for which the following algorithm is proposed: log (P(sub f)) = -4.286 - 1.390 log (R(sub 1)/R(sub3)) + 0.621 log (PAR), with P(sub t) in g C m(exp -2)/d and PAR in J m(exp -2)/d. Using this algorithm the rms accuracy of primary production estimate is 0.17 on a logarithmic scale, i.e., a factor of 1.5. Using spectral reflectance measurements in the entire visible spectral range, the central wavelength, spectral bandwidth, and radiometric noise level requirements are investigated for the channels to be used by an ocean color space mission dedicated to estimating global marine primary production and the associated carbon fluxes. Nearly all the useful information is provided by two channels centered at 440 nm and 550 nm, but the accuracy of primary production estimate appears weakly sensitive to spectral bandwidth, which, consequently, may be enlarged by several tens of nanometers. The sensitivity to radiometric noise, on the contrary, is strong, and a noise equivalent reflectance of 0.005 degraded the accuracy on the primary production estimate by a factor 2 (0.14-0.25 on a logarithmic scale). The results should be applicable to evaluating the primary production of oligotrophic and mesotrophic waters, which constitute most of the open ocean.

  17. Physical oceanographic processes influence bio-optical properties in the Tasman Sea

    NASA Astrophysics Data System (ADS)

    Cherukuru, Nagur; Davies, Peter L.; Brando, Vittorio E.; Anstee, Janet M.; Baird, Mark E.; Clementson, Lesley A.; Doblin, Martina A.

    2016-04-01

    Remote sensing observations show optical signatures to conform to the physical oceanographic patterns in the Tasman Sea. To test the link between physical oceanographic processes and bio-optical properties we investigated an in situ bio-optical dataset collected in the Tasman Sea. Analysis of in situ observations showed the presence of four different water masses in the Tasman Sea, formed by the relatively warm and saline East Australia Current (EAC) water, a mesoscale cold core eddy on the continental slope, cooler Tasman Sea water on the shelf and river plume water. The distribution of suspended substances and their inherent optical properties in these water masses were distinctly different. Light absorption and attenuation budgets indicate varying optical complexity between the water masses. Specific inherent optical properties of suspended particulate and dissolved substances in each group were different as they were influenced by physical and biogeochemical processes specific to that water mass. Remote sensing reflectance signature varied in response to changing bio-optical properties between the water masses; thus providing the link between physical oceanographic processes, bio-optical properties and the optical signature. Findings presented here extend our knowledge of the Tasman Sea, its optical environment and the role of physical oceanographic processes in influencing the inherent optical properties and remote sensing signature in this complex oceanographic region.

  18. Data Report for Calibration of a Bio-Optical Model for Narragansett Bay

    EPA Science Inventory

    Bio-optical models describe the quality and quantity of the light field at various depths in the water column. The absorption and scattering of light within the water column are wavelength dependent. The behavior of light also varies depending on the specific dissolved and partic...

  19. Bio-optical water quality dynamics observed from MERIS in Pensacola Bay, Florida

    EPA Science Inventory

    Observed bio-optical water quality data collected from 2009 to 2011 in Pensacola Bay, Florida were used to develop empirical remote sensing retrieval algorithms for chlorophyll a (Chla), colored dissolved organic matter (CDOM), and suspended particulate matter (SPM). Time-series ...

  20. Global analysis of the Deinococcus radiodurans proteome by using accurate mass tags

    PubMed Central

    Lipton, Mary S.; Paša-Tolić, Ljiljana; Anderson, Gordon A.; Anderson, David J.; Auberry, Deanna L.; Battista, John R.; Daly, Michael J.; Fredrickson, Jim; Hixson, Kim K.; Kostandarithes, Heather; Masselon, Christophe; Markillie, Lye Meng; Moore, Ronald J.; Romine, Margaret F.; Shen, Yufeng; Stritmatter, Eric; Tolić, Nikola; Udseth, Harold R.; Venkateswaran, Amudhan; Wong, Kwong-Kwok; Zhao, Rui; Smith, Richard D.

    2002-01-01

    Understanding biological systems and the roles of their constituents is facilitated by the ability to make quantitative, sensitive, and comprehensive measurements of how their proteome changes, e.g., in response to environmental perturbations. To this end, we have developed a high-throughput methodology to characterize an organism's dynamic proteome based on the combination of global enzymatic digestion, high-resolution liquid chromatographic separations, and analysis by Fourier transform ion cyclotron resonance mass spectrometry. The peptides produced serve as accurate mass tags for the proteins and have been used to identify with high confidence >61% of the predicted proteome for the ionizing radiation-resistant bacterium Deinococcus radiodurans. This fraction represents the broadest proteome coverage for any organism to date and includes 715 proteins previously annotated as either hypothetical or conserved hypothetical. PMID:12177431

  1. Development of an accurate transmission line fault locator using the global positioning system satellites

    NASA Technical Reports Server (NTRS)

    Lee, Harry

    1994-01-01

    A highly accurate transmission line fault locator based on the traveling-wave principle was developed and successfully operated within B.C. Hydro. A transmission line fault produces a fast-risetime traveling wave at the fault point which propagates along the transmission line. This fault locator system consists of traveling wave detectors located at key substations which detect and time tag the leading edge of the fault-generated traveling wave as if passes through. A master station gathers the time-tagged information from the remote detectors and determines the location of the fault. Precise time is a key element to the success of this system. This fault locator system derives its timing from the Global Positioning System (GPS) satellites. System tests confirmed the accuracy of locating faults to within the design objective of +/-300 meters.

  2. Bio-optical footprints created by mesoscale eddies in the Sargasso Sea

    NASA Astrophysics Data System (ADS)

    Siegel, D. A.; Peterson, P.; McGillicuddy, D. J., Jr.; Maritorena, S.; Nelson, N. B.

    2011-07-01

    We investigate the bio-optical footprints made by mesoscale eddies in the Sargasso Sea and the processes that create them through an eddy-centric approach. Many (>10,000) eddies are identified and followed in time using satellite altimetry observations and the spatial ocean color patterns surrounding each eddy are assessed. We find through a sequence of statistical hypothesis tests that not one but several mechanisms (i.e., eddy pumping, eddy advection and eddy-Ekman pumping) are responsible for the spatial-temporal ocean color patterns following individual eddies. Both eddy pumping and the eddy-Ekman pumping mechanisms alter subsurface nutrient distributions thereby driving biogeochemical cycles, while the eddy advection mechanism to first order stirs existing horizontal gradients in bio-optical properties. This work illustrates both the promise and some of the limitations of satellite observations for assessing the biogeochemical impacts of mesoscale eddies.

  3. Analysis of Photosynthetic Rate and Bio-Optical Components from Ocean Color Imagery

    NASA Technical Reports Server (NTRS)

    Kiefer, Dale A.; Stramski, Dariusz

    1997-01-01

    Our research over the last 5 years indicates that the successful transformation of ocean color imagery into maps of bio-optical properties will require continued development and testing of algorithms. In particular improvements in the accuracy of predicting from ocean color imagery the concentration of the bio-optical components of sea as well as the rate of photosynthesis will require progress in at least three areas: (1) we must improve mathematical models of the growth and physiological acclimation of phytoplankton; (2) we must better understand the sources of variability in the absorption and backscattering properties of phytoplankton and associated microparticles; and (3) we must better understand how the radiance distribution just below the sea surface varies as a function sun and sky conditions and inherent optical properties.

  4. Deriving in situ phytoplankton absorption for bio-optical productivity models in turbid waters

    NASA Astrophysics Data System (ADS)

    Oliver, Matthew J.; Schofield, Oscar; Bergmann, Trisha; Glenn, Scott; Orrico, Cristina; Moline, Mark

    2004-07-01

    As part of Hyperspectral Coupled Ocean Dynamics Experiment, a high-resolution hydrographic and bio-optical data set was collected from two cabled profilers at the Long-Term Ecosystem Observatory (LEO). Upwelling- and downwelling-favorable winds and a buoyant plume from the Hudson River induced large changes in hydrographic and optical structure of the water column. An absorption inversion model estimated the relative abundance of phytoplankton, colored dissolved organic matter (CDOM) and detritus, as well as the spectral exponential slopes of CDOM and detritus from in situ WET Labs nine-wavelength absorption/attenuation meter (ac-9) absorption data. Derived optical weights were proportional to the parameter concentrations and allowed for their absorptions to be calculated. Spectrally weighted phytoplankton absorption was estimated using modeled spectral irradiances and the phytoplankton absorption spectra inverted from an ac-9. Derived mean spectral absorption of phytoplankton was used in a bio-optical model estimating photosynthetic rates. Measured radiocarbon uptake productivity rates extrapolated with water mass analysis and the bio-optical modeled results agreed within 20%. This approach is impacted by variability in the maximum quantum yield (ϕmax) and the irradiance light-saturation parameter (Ek(PAR)). An analysis of available data shows that ϕmax variability is relatively constrained in temperate waters. The variability of Ek(PAR) is greater in temperate waters, but based on a sensitivity analysis, has an overall smaller impact on water-column-integrated productivity rates because of the exponential decay of light. This inversion approach illustrates the utility of bio-optical models in turbid coastal waters given the measurements of the bulk inherent optical properties.

  5. Photobiology of Symbiodinium revisited: bio-physical and bio-optical signatures

    NASA Astrophysics Data System (ADS)

    Hennige, S. J.; Suggett, D. J.; Warner, M. E.; McDougall, K. E.; Smith, D. J.

    2009-03-01

    Light is often the most abundant resource within the nutrient-poor waters surrounding coral reefs. Consequently, zooxanthellae ( Symbiodinium spp.) must continually photoacclimate to optimise productivity and ensure coral success. In situ coral photobiology is becoming dominated by routine assessments using state-of-the-art non-invasive bio-optical or chlorophyll a fluorescence (bio-physical) techniques. Multiple genetic types of Symbiodinium are now known to exist; however, little focus has been given as to how these types differ in terms of characteristics that are observable using these techniques. Therefore, this investigation aimed to revisit and expand upon a pivotal study by Iglesias-Prieto and Trench (1994) by comparing the photoacclimation characteristics of different Symbiodinium types based on their bio-physical (chlorophyll a fluorescence, reaction centre counts) and bio-optical (optical absorption, pigment concentrations) ‘signatures’. Signatures described here are unique to Symbiodinium type and describe phenotypic responses to set conditions, and hence are not suitable to describe taxonomic structure of in hospite Symbiodinium communities. In this study, eight Symbiodinium types from clades and sub-clades (A-B, F) were grown under two PFDs (Photon Flux Density) and examined. The photoacclimation response by Symbiodinium was highly variable between algal types for all bio-physical and for many bio-optical measurements; however, a general preference to modifying reaction centre content over effective antennae-absorption was observed. Certain bio-optically derived patterns, such as light absorption, were independent of algal type and, when considered per photosystem, were matched by reaction centre stoichiometry. Only by better understanding genotypic and phenotypic variability between Symbiodinium types can future studies account for the relative taxonomic and physiological contribution by Symbiodinium to coral acclimation.

  6. Physically Accurate Soil Freeze-Thaw Processes in a Global Land Surface Scheme

    NASA Astrophysics Data System (ADS)

    Cuntz, Matthias; Haverd, Vanessa

    2014-05-01

    Transfer of energy and moisture in frozen soil, and hence the active layer depth, are strongly influenced by the soil freezing curve which specifies liquid moisture content as a function of temperature. However, the curve is typically not represented in global land surface models, with less physically-based approximations being used instead. In this work, we develop a physically accurate model of soil freeze-thaw processes, suitable for use in a global land surface scheme. We incorporated soil freeze-thaw processes into an existing detailed model for the transfer of heat, liquid water and water vapor in soils, including isotope diagnostics - Soil-Litter-Iso (SLI, Haverd & Cuntz 2010), which has been used successfully for water and carbon balances of the Australian continent (Haverd et al. 2013). A unique feature of SLI is that fluxes of energy and moisture are coupled using a single system of linear equations. The extension to include freeze-thaw processes and snow maintains this elegant coupling, requiring only coefficients in the linear equations to be modified. No impedance factor for hydraulic conductivity is needed because of the formulation by matric flux potential rather than pressure head. Iterations are avoided which results in the same computational speed as without freezing. The extended model is evaluated extensively in stand-alone mode (against theoretical predictions, lab experiments and field data) and as part of the CABLE global land surface scheme. SLI accurately solves the classical Stefan problem of a homogeneous medium undergoing a phase change. The model also accurately reproduces the freezing front, which is observed in laboratory experiments (Hansson et al. 2004). SLI was further tested against observations at a permafrost site in Tibet (Weismüller et al. 2011). It reproduces seasonal thawing and freezing of the active layer to within 3 K of the observed soil temperature and to within 10% of the observed volumetric liquid soil moisture

  7. Physically Accurate Soil Freeze-Thaw Processes in a Global Land Surface Scheme

    NASA Astrophysics Data System (ADS)

    Cuntz, M.; Haverd, V.

    2013-12-01

    Transfer of energy and moisture in frozen soil, and hence the active layer depth, are strongly influenced by the soil freezing curve which specifies liquid moisture content as a function of temperature. However, the curve is typically not represented in global land surface models, with less physically-based approximations being used instead. In this work, we develop a physically accurate model of soil freeze-thaw processes, suitable for use in a global land surface scheme. We incorporated soil freeze-thaw processes into an existing detailed model for the transfer of heat, liquid water and water vapor in soils, including isotope diagnostics - Soil-Litter-Iso (SLI, Haverd & Cuntz 2010), which has been used successfully for water and carbon balances of the Australian continent (Haverd et al. 2013). A unique feature of SLI is that fluxes of energy and moisture are coupled using a single system of linear equations. The extension to include freeze-thaw processes and snow maintains this elegant coupling, requiring only coefficients in the linear equations to be modified. No impedance factor for hydraulic conductivity is needed because of the formulation by matric flux potential rather than pressure head. Iterations are avoided which results in the same computational speed as without freezing. The extended model is evaluated extensively in stand-alone mode (against theoretical predictions, lab experiments and field data) and as part of the CABLE global land surface scheme. SLI accurately solves the classical Stefan problem of a homogeneous medium undergoing a phase change. The model also accurately reproduces the freezing front, which is observed in laboratory experiments (Hansson et al. 2004). SLI was further tested against observations at a permafrost site in Tibet (Weismüller et al. 2011). It reproduces seasonal thawing and freezing of the active layer to within 3 K of the observed soil temperature and to within 10% of the observed volumetric liquid soil moisture

  8. A bio-optical approach to estimating chlorophyll-a concentration from hyperspectral remote sensing

    NASA Astrophysics Data System (ADS)

    Li, Linhai; Li, Lin; Song, Kaishan

    2010-08-01

    Eagle Creek Reservoir is one of three central Indiana reservoirs supplying drinking water for the residents of Indianapolis. The occurrence of blue-green algae blooms resulting from high nutrient input has been a major public concern so that estimation of chlorophyll-a concentration of this reservoir is significantly important for assessing the reservoir's water quality. Empirical and semi-empirical methods were used in our previous studies for estimating CHL. Due to limitations to empirical and semi-empirical methods, a bio-optical model is tested in this study. Field campaigns were carried out in Eagle Creek Reservoir in central Indiana, and water samples analyzed for water quality parameter concentrations and their inherent optical properties (IOPs). A bio-optical model parameterized with these derived IOPs is used to estimate CHL concentration through a matrix inversion of hyperspectral data, and its performance is compared with those for empirical and semi-empirical models. The result demonstrates that the bio-optical model results in a higher correlation than empirical and semi-empirical models do.

  9. Fuzzy Classification of Ocean Color Satellite Data for Bio-optical Algorithm Constituent Retrievals

    NASA Technical Reports Server (NTRS)

    Campbell, Janet W.

    1998-01-01

    The ocean has been traditionally viewed as a 2 class system. Morel and Prieur (1977) classified ocean water according to the dominant absorbent particle suspended in the water column. Case 1 is described as having a high concentration of phytoplankton (and detritus) relative to other particles. Conversely, case 2 is described as having inorganic particles such as suspended sediments in high concentrations. Little work has gone into the problem of mixing bio-optical models for these different water types. An approach is put forth here to blend bio-optical algorithms based on a fuzzy classification scheme. This scheme involves two procedures. First, a clustering procedure identifies classes and builds class statistics from in-situ optical measurements. Next, a classification procedure assigns satellite pixels partial memberships to these classes based on their ocean color reflectance signature. These membership assignments can be used as the basis for a weighting retrievals from class-specific bio-optical algorithms. This technique is demonstrated with in-situ optical measurements and an image from the SeaWiFS ocean color satellite.

  10. Bio-optical modeling of photosynthetic pigments in corals

    NASA Astrophysics Data System (ADS)

    Hochberg, Eric J.; Apprill, Amy M.; Atkinson, Marlin J.; Bidigare, Robert R.

    2006-03-01

    The spectral reflectance of coral is inherently related to the amounts of photosynthetic pigments present in the zooxanthellae. There are no studies, however, showing that the suite of major photosynthetic pigments can be predicted from optical reflectance spectra. In this study, we measured cm-scale in vivo and in situ spectral reflectance for several colonies of the massive corals Porites lobata and Porites lutea, two colonies of the branching coral Porites compressa, and one colony of the encrusting coral Montipora flabellata in Kaneohe Bay, Oahu, Hawaii. For each reflectance spectrum, we collected a tissue sample and utilized high-performance liquid chromatography to quantify six major photosynthetic pigments, located in the zooxanthellae. We used multivariate multiple regression analysis with cross-validation to build and test an empirical linear model for predicting pigment concentrations from optical reflectance spectra. The model accurately predicted concentrations of chlorophyll a, chlorophyll c 2, peridinin, diadinoxanthin, diatoxanthin and β-carotene, with correlation coefficients of 0.997, 0.941, 0.995, 0.996, 0.980 and 0.984, respectively. The relationship between predicted and actual concentrations was 1:1 for each pigment, except chlorophyll c 2. This simple empirical model demonstrates the potential for routine, rapid, non-invasive monitoring of coral-zooxanthellae status, and ultimately for remote sensing of reef biogeochemical processes.

  11. Evaluating bio-optical models to determine chlorophyll a from hyper spectral data in the turbid coastal waters of South Carolina

    NASA Astrophysics Data System (ADS)

    Hames, J. B.; Ali, K.

    2013-12-01

    Millions of people visit the beaches of South Carolina every year and the increasing utilization of the coastal waters is leading to the deterioration of water quality and the marine ecosystem. Ecological stress on these environments is reflected by the increase in the frequency and severity of Harmful Algal Blooms (HABs). This was evident during recent summer seasons particularly in the shallow nearshore waters of Long Bay, South Carolina, an open coast embayment on the South Atlantic Bight. These aspects threaten human and marine life. The early detection of HABs in the coastal waters requires more efficient and accurate monitoring tools. Remote sensing provides synoptic view of the entire Long Bay waters at high temporal coverage and allows resource managers to effectively map and monitor algal bloom development, near real time. Various remote sensing (RS) algorithms have been developed but were mostly calibrated to low resolution global data and or other specific sites. In the summer of 2013, a suite of measurements and water samples were collected from 15 locations along the nearshore waters of Long Bay using the Grice Laboratory R/V. In this study, we evaluate the efficiency of 10 bio-optical blue-green and NIR-red based RS models applied to GER 1500 hyper spectral reflectance data to predict chlorophyll a, a proxy for phytoplankton density, in the Long Bay waters of SC. Efficiency of the algorithms performance in the study site were tested through a least squares regression and residual analysis. Results show that among the selected suite of algorithms the blue green models by Darecki and Stramski (2004) produced R2 of 0.68 with RMSE=0.39μg/l, Oc4v4 model by O'Reilly et al. (2000) gave R2 of 0.62 with RMSE=0.73ug/l, and the Oc2v4 also by O'Reilly et al (2000) gave R2 of 0.69 with RMSE=0.65. Among the NIR-red models, Moses et al (2009) two-band algorithm produced R2 of 0.75 and RMSE=1.79, and the three-band version generated R2 of 0.81 and RMSE=2.25ug

  12. Communication: An accurate global potential energy surface for the ground electronic state of ozone

    SciTech Connect

    Dawes, Richard E-mail: hguo@unm.edu; Lolur, Phalgun; Li, Anyang; Jiang, Bin; Guo, Hua E-mail: hguo@unm.edu

    2013-11-28

    We report a new full-dimensional and global potential energy surface (PES) for the O + O{sub 2} → O{sub 3} ozone forming reaction based on explicitly correlated multireference configuration interaction (MRCI-F12) data. It extends our previous [R. Dawes, P. Lolur, J. Ma, and H. Guo, J. Chem. Phys. 135, 081102 (2011)] dynamically weighted multistate MRCI calculations of the asymptotic region which showed the widely found submerged reef along the minimum energy path to be the spurious result of an avoided crossing with an excited state. A spin-orbit correction was added and the PES tends asymptotically to the recently developed long-range electrostatic model of Lepers et al. [J. Chem. Phys. 137, 234305 (2012)]. This PES features: (1) excellent equilibrium structural parameters, (2) good agreement with experimental vibrational levels, (3) accurate dissociation energy, and (4) most-notably, a transition region without a spurious reef. The new PES is expected to allow insight into the still unresolved issues surrounding the kinetics, dynamics, and isotope signature of ozone.

  13. The Ocean Colour Climate Change Initiative: III. A Round-Robin Comparison on In-Water Bio-Optical Algorithms

    NASA Technical Reports Server (NTRS)

    Brewin, Robert J.W.; Sathyendranath, Shubha; Muller, Dagmar; Brockmann, Carsten; Deschamps, Pierre-Yves; Devred, Emmanuel; Doerffer, Roland; Fomferra, Norman; Franz, Bryan; Grant, Mike; Groom, Steve; Horseman, Andrew; Hu, Chuanmin; Krasemann, Hajo; Lee, ZhongPing; Maritorena, Stephane; Melin, Frederic; Peters, Marco; Platt, Trevor; Regner, Peter; Smyth, Tim; Steinmetz, Francois; Swinton, John; Werdell, Jeremy; White, George N., III

    2013-01-01

    Satellite-derived remote-sensing reflectance (Rrs) can be used for mapping biogeochemically relevant variables, such as the chlorophyll concentration and the Inherent Optical Properties (IOPs) of the water, at global scale for use in climate-change studies. Prior to generating such products, suitable algorithms have to be selected that are appropriate for the purpose. Algorithm selection needs to account for both qualitative and quantitative requirements. In this paper we develop an objective methodology designed to rank the quantitative performance of a suite of bio-optical models. The objective classification is applied using the NASA bio-Optical Marine Algorithm Dataset (NOMAD). Using in situ Rrs as input to the models, the performance of eleven semianalytical models, as well as five empirical chlorophyll algorithms and an empirical diffuse attenuation coefficient algorithm, is ranked for spectrally-resolved IOPs, chlorophyll concentration and the diffuse attenuation coefficient at 489 nm. The sensitivity of the objective classification and the uncertainty in the ranking are tested using a Monte-Carlo approach (bootstrapping). Results indicate that the performance of the semi-analytical models varies depending on the product and wavelength of interest. For chlorophyll retrieval, empirical algorithms perform better than semi-analytical models, in general. The performance of these empirical models reflects either their immunity to scale errors or instrument noise in Rrs data, or simply that the data used for model parameterisation were not independent of NOMAD. Nonetheless, uncertainty in the classification suggests that the performance of some semi-analytical algorithms at retrieving chlorophyll is comparable with the empirical algorithms. For phytoplankton absorption at 443 nm, some semi-analytical models also perform with similar accuracy to an empirical model. We discuss the potential biases, limitations and uncertainty in the approach, as well as additional

  14. OCTS and SeaWiFS Bio-Optical Algorithm and Product Validation and Intercomparison in US Coastal Waters

    NASA Technical Reports Server (NTRS)

    Brown, Christopher W.; Brock, John C.

    1998-01-01

    The successful launch of the National Space Development Agency of Japan (NASDA) Ocean Color and Temperature Sensor (OCTS) in August 1996, and the launch of Orbital Science Corporation's (OSC) Sea-viewing Wide-Field-of-view Sensor (SeaWiFS) in August 1997 signaled the beginning of a new era for ocean color research and application. These data may be used to remotely evaluate 1) water quality, 2) transport of sediments and adhered pollutants, 3) primary production, upon which commercial shellfish and finfish populations depend for food, and 4) harmful algal blooms which pose a threat to public health and economies of affected areas. Several US government agencies have recently expressed interest in monitoring U.S. coastal waters using optical remote sensing. This renewed interest is broadly driven by 1) resource management concerns over the impact of coastward shifts in population and land use on the ecosystems of estuaries, wetlands, nearshore benthic environments and fisheries, 2) recognition of the need to understand short time scale global change due to urbanization of sensitive land-margin ecosystems, and 3) national security issues. Satellite ocean color sensors have the potential to furnish data at the appropriate time and space scales to evaluate and resolve these concerns and problems. In this draft technical memorandum, we outline our progress during the first year of our SIMBIOS project to evaluate ocean color bio-optical algorithms and products generated using OCTS and SeaWiFS data in coastal US waters.

  15. OCTS And Seawifs Bio-Optical Algorithm and Product Vaildattion and Intercomparison in US Coastal Waters

    NASA Technical Reports Server (NTRS)

    Brow, Chirstopher; Subramaniam, Ajit; Culver, Mary; Brock, John C.

    2000-01-01

    Monitoring the health of U.S. coastal waters is an important goal of the National Oceanic and Atmospheric Administration (NOAA). Satellite sensors are capable of providing daily synoptic data of large expanses of the U.S. coast. Ocean color sensor, in particular, can be used to monitor the water quality of coastal waters on an operational basis. To appraise the validity of satellite-derived measurements, such as chlorophyll concentration, the bio-optical algorithms used to derive them must be evaluated in coastal environments. Towards this purpose, over 21 cruises in diverse U.S. coastal waters have been conducted. Of these 21 cruises, 12 have been performed in conjunction with and under the auspices of the NASA/SIMBIOS Project. The primary goal of these cruises has been to obtain in-situ measurements of downwelling irradiance, upwelling radiance, and chlorophyll concentrations in order to evaluate bio-optical algorithms that estimate chlorophyll concentration. In this Technical Memorandum, we evaluate the ability of five bio-optical algorithms, including the current SeaWiFS algorithm, to estimate chlorophyll concentration in surface waters of the South Atlantic Bight (SAB). The SAB consists of a variety of environments including coastal and continental shelf regimes, Gulf Stream waters, and the Sargasso Sea. The biological and optical characteristics of the region is complicated by temporal and spatial variability in phytoplankton composition, primary productivity, and the concentrations of colored dissolved organic matter (CDOM) and suspended sediment. As such, the SAB is an ideal location to test the robustness of algorithms for coastal use.

  16. Validation of MERIS bio-optical products with in situ data in the turbid Lithuanian Baltic Sea coastal waters

    NASA Astrophysics Data System (ADS)

    Vaičiūtė, Diana; Bresciani, Mariano; Bučas, Martynas

    2012-01-01

    In this study bio-optical water quality indicators, chlorophyll a, colored dissolved organic matter (CDOM), and total suspended matter (TSM) were derived from the Envisat-MERIS satellite data and were compared with in situ measurements collected in the Lithuanian optically Case 2 coastal waters of the Baltic Sea. Eight MERIS full-resolution Level 1b images, acquired during late spring and summer 2010, were processed using five, neural network-based processors for optically Case 2 or coastal and inland waters: FUB, C2R, Eutrophic, Boreal, and standard MERIS Level 2. Results showed that the FUB processor provided the most accurate estimates of the concentration of chlorophyll a [R2=69%; mean absolute error(MAE)=7.76 mg/m3] and TSM (R2=89%; MAE=3.93 g/m3). In situ CDOM absorption was most accurately estimated using the Boreal processor (R2=69%; MAE=0.20 1/m). We analyzed the factors that were most influential in explaining the differences in the accuracy and found that the Secchi depth and the sampling time were the most important factors. The greatest differences between satellite-derived and in situ values of water quality indicators were in correspondence with the lowest Secchi depth, suggesting that the plume zone created by freshwater coming from the hyper-eutrophic lagoon was the most sensitive region for the validation. The evident match between in situ measurements and satellite-based estimates was observed when field measurements were acquired 1-2 h before to approximately 2-4 h after the satellite overpass. Results of this validation work confirmed that remote sensing techniques are suitable for monitoring the changes of optical constituents in Lithuanian coastal waters.

  17. A neural network-based method for merging ocean color and Argo data to extend surface bio-optical properties to depth: Retrieval of the particulate backscattering coefficient

    NASA Astrophysics Data System (ADS)

    Sauzède, R.; Claustre, H.; Uitz, J.; Jamet, C.; Dall'Olmo, G.; D'Ortenzio, F.; Gentili, B.; Poteau, A.; Schmechtig, C.

    2016-04-01

    The present study proposes a novel method that merges satellite ocean color bio-optical products with Argo temperature-salinity profiles to infer the vertical distribution of the particulate backscattering coefficient (bbp). This neural network-based method (SOCA-BBP for Satellite Ocean-Color merged with Argo data to infer the vertical distribution of the Particulate Backscattering coefficient) uses three main input components: (1) satellite-based surface estimates of bbp and chlorophyll a concentration matched up in space and time with (2) depth-resolved physical properties derived from temperature-salinity profiles measured by Argo profiling floats and (3) the day of the year of the considered satellite-Argo matchup. The neural network is trained and validated using a database including 4725 simultaneous profiles of temperature-salinity and bio-optical properties collected by Bio-Argo floats, with concomitant satellite-derived products. The Bio-Argo profiles are representative of the global open-ocean in terms of oceanographic conditions, making the proposed method applicable to most open-ocean environments. SOCA-BBP is validated using 20% of the entire database (global error of 21%). We present additional validation results based on two other independent data sets acquired (1) by four Bio-Argo floats deployed in major oceanic basins, not represented in the database used to train the method; and (2) during an AMT (Atlantic Meridional Transect) field cruise in 2009. These validation tests based on two fully independent data sets indicate the robustness of the predicted vertical distribution of bbp. To illustrate the potential of the method, we merged monthly climatological Argo profiles with ocean color products to produce a depth-resolved climatology of bbp for the global ocean.

  18. Bio-Optical and Geochemical Properties of the South Atlantic Subtropical Gyre

    NASA Technical Reports Server (NTRS)

    Signorini, S. R.; Hooker, Stanford B.; McClain, Charles R.

    2003-01-01

    An investigation of the bio-optical properties of the South Atlantic subtropical gyre (SASG) was conducted using data primarily from the UK Atlantic Meridional Transect (AMT) program and SeaWiFS. The AMT cruises extend from the UK to the Falklands Islands (sailing on the RRS James Clark Ross) with the purpose of improving our knowledge of surface layer hydrography, biogeochemical processes, ecosystem dynamics and food webs across basin scales in the Atlantic Ocean. Two objectives of the AMT program relevant to this study are the characterization of biogeochemical provinces and the analysis of optical and pigment parameters in connection with remote sensing ocean color data. The primary focus of this NASA Technical Memorandum is on the variability of the vertical distribution of phytoplankton pigments and associated absorption properties across the SASG, and their relevance to remote sensing algorithms. Therefore, a subset of the AMT data within the SASG from all available cruises was used in the analyses. One of the challenges addressed here is the determination of the SASG geographic boundaries. One of the major problems is to reconcile the properties of biogeochemical provinces. We use water mass analysis, dynamics of ocean currents, and meridional gradients of bio-optical properties, to identify the SASG boundaries.

  19. The Bermuda BioOptics Project (BBOP) Years 9-11

    NASA Technical Reports Server (NTRS)

    Maritorena, S.; Siegel, D. A.; Nelson, Norm B.

    2004-01-01

    The Bermuda BioOptics Project (BBOP) is a collaborative effort between the Institute for Computational Earth System Science (ICESS) at the University of California at Santa Barbara (UCSB) and the Bermuda Biological Station for Research (BBSR). This research program is designed to characterize light availability and utilization in the Sargasso Sea, and to provide an optical link by which biogeochemical observations may be used to evaluate bio-optical models for pigment concentration, primary production, and sinking particle fluxes from satellite-based ocean color sensors. The BBOP time-series was initiated in 1992, and is carried out in conjunction with the U.S. JGOFS Bermuda Atlantic Time-series Study (BATS) at the Bermuda Biological Station for Research. The BATS program itself has been observing biogeochemical processes (primary productivity, particle flux and elemental cycles) in the mesotrophic waters of the Sargasso Sea since 1988. Closely affiliated with BBOP and BATS is a separate NASA-funded study of the spatial variability of biogeochemical processes in the Sargasso Sea using high-resolution AVHRR and SeaWiFS data collected at Bermuda. The collaboration between BATS and BBOP measurements has resulted in a unique data set that addresses not only the SIMBIOS goals but also the broader issues of important factors controlling the carbon cycle.

  20. The Bermuda BioOptics Project (BBOP) Years 9-11

    NASA Technical Reports Server (NTRS)

    Nelson, Norm

    2003-01-01

    The Bermuda BioOptics Project (BBOP) is a collaborative effort between the Institute for Computational Earth System Science (ICESS) at the University of California at Santa Barbara (UCSB) and the Bermuda Biological Station for Research (BBSR). This research program is designed to characterize light availability and utilization in the Sargasso Sea, and to provide an optical link by which biogeochemical observations may be used to evaluate bio-optical models for pigment concentration, primary production, and sinking particle fluxes from satellite-based ocean color sensors. The BBOP time-series was initiated in 1992, and is carried out in conjunction with the U.S. JGOFS Bermuda Atlantic Time-series Study (BATS) at the Bermuda Biological Station for Research. The BATS program itself has been observing biogeochemical processes (primary productivity, particle flux and elemental cycles) in the mesotrophic waters of the Sargasso Sea since 1988. Closely affiliated with BBOP and BATS is a separate NASA-funded study of the spatial variability of biogeochemical processes in the Sargasso Sea using high-resolution AVHRR and SeaWiFS data collected at Bermuda. The collaboration between BATS and BBOP measurements has resulted in a unique data set that addresses not only the SIMBIOS goals but also the broader issues of important factors controlling the carbon cycle. This final report addresses specific research activities, research results, and lists of presentations and papers submitted for publication.

  1. Design and performance analysis of a bio-optical sub-assembly for diffuse optical technologies

    NASA Astrophysics Data System (ADS)

    Jeong, Je-Myung; Park, Kyoungsu; Kim, Sehwan

    2014-11-01

    This paper presents a compact, multi-wavelength, and high-frequency-response light source named the bio-optical sub-assembly (BiOSA). The BiOSA is used to measure the absorption and the reduced scattering coefficients from diffuse optics-based biomedical systems. It is equipped with six laser diodes and one optical fiber with a 400- μm diameter core. Simulations can be used to determine the design parameters and to confirm the feasibility of the BiOSA. The evaluation results indicate that the coupling efficiency of the fabricated BiOSA is 80 ˜ 85%, and the frequency response is up to 3.38 GHz.

  2. Ship and satellite bio-optical research in the California Bight

    NASA Technical Reports Server (NTRS)

    Smith, R. C.; Baker, K. S.

    1982-01-01

    Mesoscale biological patterns and processes in productive coastal waters were studied. The physical and biological processes leading to chlorophyll variability were investigated. The ecological and evolutionary significance of this variability, and its relation to the prediction of fish recruitment and marine mammal distributions was studied. Seasonal primary productivity (using chlorophyll as an indication of phytoplankton biomass) for the entire Southern California Bight region was assessed. Complementary and contemporaneous ship and satellite (Nimbus 7-CZCS) bio-optical data from the Southern California Bight and surrounding waters were obtained and analyzed. These data were also utilized for the development of multi-platform sampling strategies and the optimization of algorithms for the estimation of phytoplankton biomass and primary production from satellite imagery.

  3. Accurate single-sequence prediction of solvent accessible surface area using local and global features

    PubMed Central

    Faraggi, Eshel; Zhou, Yaoqi; Kloczkowski, Andrzej

    2014-01-01

    We present a new approach for predicting the Accessible Surface Area (ASA) using a General Neural Network (GENN). The novelty of the new approach lies in not using residue mutation profiles generated by multiple sequence alignments as descriptive inputs. Instead we use solely sequential window information and global features such as single-residue and two-residue compositions of the chain. The resulting predictor is both highly more efficient than sequence alignment based predictors and of comparable accuracy to them. Introduction of the global inputs significantly helps achieve this comparable accuracy. The predictor, termed ASAquick, is tested on predicting the ASA of globular proteins and found to perform similarly well for so-called easy and hard cases indicating generalizability and possible usability for de-novo protein structure prediction. The source code and a Linux executables for GENN and ASAquick are available from Research and Information Systems at http://mamiris.com, from the SPARKS Lab at http://sparks-lab.org, and from the Battelle Center for Mathematical Medicine at http://mathmed.org. PMID:25204636

  4. Accurate single-sequence prediction of solvent accessible surface area using local and global features.

    PubMed

    Faraggi, Eshel; Zhou, Yaoqi; Kloczkowski, Andrzej

    2014-11-01

    We present a new approach for predicting the Accessible Surface Area (ASA) using a General Neural Network (GENN). The novelty of the new approach lies in not using residue mutation profiles generated by multiple sequence alignments as descriptive inputs. Instead we use solely sequential window information and global features such as single-residue and two-residue compositions of the chain. The resulting predictor is both highly more efficient than sequence alignment-based predictors and of comparable accuracy to them. Introduction of the global inputs significantly helps achieve this comparable accuracy. The predictor, termed ASAquick, is tested on predicting the ASA of globular proteins and found to perform similarly well for so-called easy and hard cases indicating generalizability and possible usability for de-novo protein structure prediction. The source code and a Linux executables for GENN and ASAquick are available from Research and Information Systems at http://mamiris.com, from the SPARKS Lab at http://sparks-lab.org, and from the Battelle Center for Mathematical Medicine at http://mathmed.org. PMID:25204636

  5. Assessment of water constituents in highly turbid productive water by optimization bio-optical retrieval model after optical classification

    NASA Astrophysics Data System (ADS)

    Huang, Changchun; Li, Yunmei; Yang, Hao; Li, Junsheng; Chen, Xia; Sun, Deyong; Le, Chengfeng; Zou, Jun; Xu, Liangjiang

    2014-11-01

    Based on the bio-optical properties of highly turbid productive inland waterbody, Taihu Lake, a novel bio-optical optimization algorithm was developed to estimate chlorophyll-a concentration (Cchla) and total suspended matter concentration (CTSM) after optical classification. Between 2006 and 2013, 1080 in situ samples collected from four inland lakes in China were utilized to test this optimization algorithm. All data were classified into four classes based on a new bio-optical classification method. The retrieval results of CTSM and Cchla exhibit a good consistency with in situ measured CTSM and Cchla. CTSM retrieval accuracies (evaluated by the root mean square of percentage errors: RMSPs) of classes 1, 2, 3, and 4 were 35.77%, 16.09%, 28.42%, and 26.86% for data1 and were 32.15%, 33.14%, 47.71%, and 34.89% for data3, respectively. Cchla retrieval accuracies (RMSPs) of classes 1, 2, 3, and 4 were 32.49%, 20.05%, 42.01%, and 34.85% for data1, were 44.71%, 32.59%, 47.92%, and 38.11% for data2, and were 33.12%, 25.65%, 70.88%, and 23.57% for data3, respectively. The optimization algorithm was also tested by the simulated data of Medium Resolution Imaging Spectrometer, Moderate Resolution Imaging Spectroradiometer, and Sea-viewing Wide Field-of-view Sensor satellite sensors' center wavelengths. The validation shows a good correlation with the measured CTSM and Cchla. All these examinations demonstrate that the bio-optical optimization algorithm and classification are valid and robust for both the in situ data and the simulated satellite data. The optical relationships of aph(4 4 0) to Cchla and bbp(4 4 0) to CTSM are reasonable and effective. In summary, the results present that the bio-optical optimization algorithm proposed in this study shows high potential application to various water types and satellite sensors. The retrieval accuracy of CTSM and Cchla derived by bio-optical optimization algorithm was significantly improved after classification.

  6. Toward spectroscopically accurate global ab initio potential energy surface for the acetylene-vinylidene isomerization

    SciTech Connect

    Han, Huixian; Li, Anyang; Guo, Hua

    2014-12-28

    A new full-dimensional global potential energy surface (PES) for the acetylene-vinylidene isomerization on the ground (S{sub 0}) electronic state has been constructed by fitting ∼37 000 high-level ab initio points using the permutation invariant polynomial-neural network method with a root mean square error of 9.54 cm{sup −1}. The geometries and harmonic vibrational frequencies of acetylene, vinylidene, and all other stationary points (two distinct transition states and one secondary minimum in between) have been determined on this PES. Furthermore, acetylene vibrational energy levels have been calculated using the Lanczos algorithm with an exact (J = 0) Hamiltonian. The vibrational energies up to 12 700 cm{sup −1} above the zero-point energy are in excellent agreement with the experimentally derived effective Hamiltonians, suggesting that the PES is approaching spectroscopic accuracy. In addition, analyses of the wavefunctions confirm the experimentally observed emergence of the local bending and counter-rotational modes in the highly excited bending vibrational states. The reproduction of the experimentally derived effective Hamiltonians for highly excited bending states signals the coming of age for the ab initio based PES, which can now be trusted for studying the isomerization reaction.

  7. A case study on bio-optical and radiometric quantities in northwest European shelf seas

    NASA Astrophysics Data System (ADS)

    Garaba, Shungu; Zielinski, Oliver

    2013-04-01

    Colour of seawater has become an integral tool in understanding surface marine ecosystems and processes. Additionally, operational oceanographic observatories are becoming more prominent these days while at the same time hyperspectral radiometric sensors are becoming increasingly affordable. This has driven a wide spread use of these hyperspectral sensors to measure reflectance above the water surface from stationary and mobile platforms alike. As enormous amounts of data are produced and favourably processed in real-time, effective quality control procedures become more than just supporting tools, but a crucial prerequisite for trustworthy and manageable information. Here, we use bio-geophysical and hyperspectral radiometric measurements from German Bight (GB), North Sea (NS), Inner Seas (ISS), Irish Sea (IS) and Celtic Sea (CS) to identify and establish relationships between colour producing agents (CPAs) and perceived colour of seawater. In order to obtain valid optical measurements, meteorological and sunglint contamination were mitigated using state-of-the-art quality control protocols. The remote sensing reflectance measured is transformed into discrete Forel-Ule numerical indices (FUI), 1 (indigo-blue, oligotrophic) to 21 (cola brown, hyper-eutrophic). We present a novel approach of estimating which of the three main CPAs of seawater control perceived colour of seawater. Our bio-optical models for estimating FUI for measured CPAs; chlorophyll (Chl-a), coloured dissolved organic material (CDOM) and suspended particulate material (SPM) had correlation coefficients, R² (GB = 0.98, NS = 0.23, ISS=0.99, IS=0.63, CS = 0.16). It was also observed that salinity can be estimated from coloured dissolved organic matter with good accuracy, R² (GB = 0.94, NS = 0.44, ISS=0.90, IS=0.85, CS = 0.51). We show that ocean colour products i.e. reflectance and perceived colour of seawater can be used to infer, with good accuracy, environmental parameters e.g. Chl-a, CDOM, SPM

  8. Development of Bio-Optical Algorithms for Geostationary Ocean Color Imager

    NASA Astrophysics Data System (ADS)

    Ryu, J.; Moon, J.; Min, J.; Palanisamy, S.; Han, H.; Ahn, Y.

    2007-12-01

    GOCI, the first Geostationary Ocean Color Imager, shall be operated in a staring-frame capture mode onboard its Communication Ocean and Meteorological Satellite (COMS) and tentatively scheduled for launch in 2008. The mission concept includes eight visible-to-near-infrared bands, 0.5 km pixel resolution, and a coverage region of 2,500 ¢®¢¯ 2,500 km centered at Korea. The GOCI is expected to provide SeaWiFS quality observations for a single study area with imaging interval of 1 hour from 10 am to 5 pm. In the GOCI swath area, the optical properties of the East Sea (typical of Case-I water), the Yellow Sea and East China Sea (typical of Case-II water) are investigated. For developing the GOCI bio-optical algorithms in optically more complex waters, it is necessary to study and understand the optical properties around the Korean Sea. Radiometric measurements were made using WETLabs AC-S, TriOS RAMSES ACC/ARC, and ASD FieldSpec Pro Dual VNIR Spectroradiometer. Seawater samples were collected concurrently with the radiometric measurements at about 300 points around the Korean Sea during 1998 to 2007. The absorption coefficients were determined using Perkin-Elmer Lambda 19 dual-beam spectrophotometer. We analyzed the absorption coefficient of sea water constituents such as phytoplankton, Suspended Sediment (SS) and Dissolved Organic Matter (DOM). Two kinds of chlorophyll algorithms are developed by using statistical regression and fluorescence-based technique considering the bio- optical properties in Case-II waters. Fluorescence measurements were related to in situ Chl-a concentrations to obtain the Flu(681), Flu(688) and Flu(area) algorithms, which were compared with those from standard spectral ratios of the remote sensing reflectance. The single band algorithm for is derived by relationship between Rrs (555) and in situ concentration. The CDOM is estimated by absorption spectra and its slope centered at 440 nm wavelength. These standard algorithms will be

  9. Global climate modeling of Saturn's atmosphere: fast and accurate radiative transfer and exploration of seasonal variability

    NASA Astrophysics Data System (ADS)

    Guerlet, Sandrine; Spiga, A.; Sylvestre, M.; Fouchet, T.; Millour, E.; Wordsworth, R.; Leconte, J.; Forget, F.

    2013-10-01

    Recent observations of Saturn’s stratospheric thermal structure and composition revealed new phenomena: an equatorial oscillation in temperature, reminiscent of the Earth's Quasi-Biennal Oscillation ; strong meridional contrasts of hydrocarbons ; a warm “beacon” associated with the powerful 2010 storm. Those signatures cannot be reproduced by 1D photochemical and radiative models and suggest that atmospheric dynamics plays a key role. This motivated us to develop a complete 3D General Circulation Model (GCM) for Saturn, based on the LMDz hydrodynamical core, to explore the circulation, seasonal variability, and wave activity in Saturn's atmosphere. In order to closely reproduce Saturn's radiative forcing, a particular emphasis was put in obtaining fast and accurate radiative transfer calculations. Our radiative model uses correlated-k distributions and spectral discretization tailored for Saturn's atmosphere. We include internal heat flux, ring shadowing and aerosols. We will report on the sensitivity of the model to spectral discretization, spectroscopic databases, and aerosol scenarios (varying particle sizes, opacities and vertical structures). We will also discuss the radiative effect of the ring shadowing on Saturn's atmosphere. We will present a comparison of temperature fields obtained with this new radiative equilibrium model to that inferred from Cassini/CIRS observations. In the troposphere, our model reproduces the observed temperature knee caused by heating at the top of the tropospheric aerosol layer. In the lower stratosphere (20mbar

  10. Physical activity intensity can be accurately monitored by smartphone global positioning system 'app'.

    PubMed

    Gordon, Brett Ashley; Bruce, Lyndell; Benson, Amanda Clare

    2016-08-01

    Monitoring physical activity is important to better individualise health and fitness benefits. This study assessed the concurrent validity of a smartphone global positioning system (GPS) 'app' and a sport-specific GPS device with a similar sampling rate, to measure physical activity components of speed and distance, compared to a higher sampling sport-specific GPS device. Thirty-eight (21 female, 17 male) participants, mean age of 24.68, s = 6.46 years, completed two 2.400 km trials around an all-weather athletics track wearing GPSports Pro™ (PRO), GPSports WiSpi™ (WISPI) and an iPhone™ with a Motion X GPS™ 'app' (MOTIONX). Statistical agreement, assessed using t-tests and Bland-Altman plots, indicated an (mean; 95% LOA) underestimation of 2% for average speed (0.126 km·h(-1); -0.389 to 0.642; p < .001), 1.7% for maximal speed (0.442 km·h(-1); -2.676 to 3.561; p = .018) and 1.9% for distance (0.045 km; -0.140 to 0.232; p < .001) by MOTIONX compared to that measured by PRO. In contrast, compared to PRO, WISPI overestimated average speed (0.232 km·h(-1); -0.376 to 0.088; p < .001) and distance (0.083 km; -0.129 to -0.038; p < .001) by 3.5% whilst underestimating maximal speed by 2.5% (0.474 km·h(-1); -1.152 to 2.099; p < .001). Despite the statistically significant difference, the MOTIONX measures intensity of physical activity, with a similar error as WISPI, to an acceptable level for population-based monitoring in unimpeded open-air environments. This presents a low-cost, minimal burden opportunity to remotely monitor physical activity participation to improve the prescription of exercise as medicine. PMID:26505223

  11. Seasonal variability of bio-optical and physical properties in the Sargasso Sea

    NASA Technical Reports Server (NTRS)

    Dickey, T.; Granata, T.; Marra, J.; Langdon, C.; Wiggert, J.; Chai-Jochner, Z.; Hamilton, M.; Vazquez, J.; Stramska, M.; Bidigare, R.

    1993-01-01

    The seasonal variability of bio-optical and physical properties within the upper ocean at a site in the Sargasso Sea has been observed in multivariable moored systems during a 9-month period. In addition, complementary meteorological data, sea surface height and sea surface temperature maps, and expendable bathythermograph and shipboard profile data have been utilized for interpretation. The observations during March are characteristic of late wintertime conditions of a deep isothermal layer, but with intervening periods of warming due to the advection of warm outbreak waters associated with Gulf Stream meanders. The mixed layer depth shoals from greater than 160 m to about 25 m in late March (spring transition). Phytoplankton blooms follow the mixed layer shoaling. A succession of phytoplankton populations occurs during this transitional interval. The mixed layer remains near 25 m for the summer and deepens in mid-September. A relatively intense subsurface maximum in chlorophyll develops at about 75 m following the spring transition. The maximum persists, but weakens in mid-summer.

  12. Yearlong, Daily Assessments of Bio-Optical Distributions under Perennial Ice Cover in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Laney, S. R.; Toole, J. M.; Krishfield, R. A.

    2013-12-01

    Over the past three years eight Ice-Tethered Profilers have been outfitted with a new bio-optical sensor suite and have been deployed under perennial ice cover in the Arctic Ocean. This sensor suite enables the measurement of chlorophyll (a proxy for algal biomass), colored dissolved organic matter concentration, and particular backscatter intensities throughout the entire upper 750 m of the under-ice water column. An irradiance sensor additionally provides concurrent measurements of the light field underneath ice cover during times of the year that receive insolation. Two of these profilers have operated for a full year, returning multiple daily profiles of these basic biogeochemical optical properties with sub-meter vertical resolution. These observations provide unprecedented insight into the basic optical seasonality of the pelagic ocean environment under perennial ice cover, including the timing of important biogeochemical events in the Arctic such as periods of high under-ice productivity and the subsequent export of organic matter to the deep ocean.

  13. Invited Review Article: Review of centrifugal microfluidic and bio-optical disks

    NASA Astrophysics Data System (ADS)

    Nolte, David D.

    2009-10-01

    Spinning biodisks have advantages that make them attractive for specialized biochip applications. The two main classes of spinning biodisks are microfluidic disks and bio-optical compact disks (BioCD). Microfluidic biodisks take advantage of noninertial pumping for lab-on-a-chip devices using noninertial valves and switches under centrifugal and Coriolis forces to distribute fluids about the disks. BioCDs use spinning-disk interferometry, under the condition of common-path phase quadrature, to perform interferometric label-free detection of molecular recognition and binding. The optical detection of bound molecules on a disk is facilitated by rapid spinning that enables high-speed repetitive sampling to eliminate 1/f noise through common-mode rejection of intensity fluctuations and extensive signal averaging. Multiple quadrature classes have been developed, such as microdiffraction, in-line, phase contrast, and holographic adaptive optics. Thin molecular films are detected through the surface dipole density with a surface height sensitivity for the detection of protein spots that is approximately 1 pm. This sensitivity easily resolves a submonolayer of solid-support immobilized antibodies and their antigen targets. Fluorescence and light scattering provide additional optical detection techniques on spinning disks. Immunoassays have been applied to haptoglobin using protein A/G immobilization of antibodies and to prostate specific antigen. Small protein spots enable scalability to many spots per disk for high-throughput and highly multiplexed immonoassays.

  14. Invited Review Article: Review of centrifugal microfluidic and bio-optical disks

    PubMed Central

    Nolte, David D.

    2009-01-01

    Spinning biodisks have advantages that make them attractive for specialized biochip applications. The two main classes of spinning biodisks are microfluidic disks and bio-optical compact disks (BioCD). Microfluidic biodisks take advantage of noninertial pumping for lab-on-a-chip devices using noninertial valves and switches under centrifugal and Coriolis forces to distribute fluids about the disks. BioCDs use spinning-disk interferometry, under the condition of common-path phase quadrature, to perform interferometric label-free detection of molecular recognition and binding. The optical detection of bound molecules on a disk is facilitated by rapid spinning that enables high-speed repetitive sampling to eliminate 1∕f noise through common-mode rejection of intensity fluctuations and extensive signal averaging. Multiple quadrature classes have been developed, such as microdiffraction, in-line, phase contrast, and holographic adaptive optics. Thin molecular films are detected through the surface dipole density with a surface height sensitivity for the detection of protein spots that is approximately 1 pm. This sensitivity easily resolves a submonolayer of solid-support immobilized antibodies and their antigen targets. Fluorescence and light scattering provide additional optical detection techniques on spinning disks. Immunoassays have been applied to haptoglobin using protein A∕G immobilization of antibodies and to prostate specific antigen. Small protein spots enable scalability to many spots per disk for high-throughput and highly multiplexed immonoassays. PMID:19895047

  15. Bio-optical profile data report coastal transition zone program, R/V Point Sur, June 15-28, 1987

    NASA Technical Reports Server (NTRS)

    Davis, Curtiss O.; Rhea, W. Joseph

    1990-01-01

    Twenty vertical profiles of the bio-optical properties of the ocean were made during a research cruise on the R/V Point Sur, June 15 to 28, 1987, as part of the Coastal Transition Zone Program off Point Arena, California. Extracted chlorophyll values were also measured at some stations to provide calibration data for the in situ fluorometer. This summary provides investigators with an overview of the data collected. The entire data set is available in digital form.

  16. Bio-optical profile data report coastal transition zone program, R/V Thomas Washington, June 24 - July 21, 1988

    NASA Technical Reports Server (NTRS)

    Davis, Curtiss O.; Rhea, W. Joseph

    1990-01-01

    Twenty-three vertical profiles of the bio-optical properties of the ocean were made during a research cruise on the R/V Thomas Washington, June 24 to July 21, 1988, as part of the Coastal Transition Zone Program off Point Arena, California. A summary is given, to provide investigators with an overview of the data collected. The entire data set is available in digital form for interested researchers.

  17. IGS-global ionospheric maps for accurate computation of GPS single- frequency ionospheric delay-simulation study

    NASA Astrophysics Data System (ADS)

    Farah, A.

    The Ionospheric delay is still one of the largest sources of error that affects the positioning accuracy of any satellite positioning system. This problem could be solved due to the dispersive nature of the Ionosphere by combining simultaneous measurements of signals at two different frequencies but it is still there for single- frequency users. Much effort has been made in establishing models for single- frequency users to make this effect as small as possible. These models vary in accuracy, input data and computational complexity, so the choice between the different models depends on the individual circumstances of the user. From the simulation point of view, the model needed should be accurate with a global coverage and good description to the Ionosphere's variable nature with both time and location. The author reviews some of these established models, starting with the BENT model, the Klobuchar model and the IRI (International Reference Ionosphere) model. Since quiet a long time, Klobuchar model considers the most widely used model ever in this field, due to its simplicity and time saving. Any GPS user could find Klobuchar model's coefficients in the broadcast navigation message. CODE, Centre for Orbit Determination in Europe provides a new set of coefficients for Klobuchar model, which gives more accurate results for the Ionospheric delay computation. IGS (International GPS Service) services include providing GPS community with a global Ionospheric maps in IONEX-format (IONosphere Map Exchange format) which enables the computation of the Ionospheric delay at the desired location and time. The study was undertaken from GPS-data simulation point of view. The aim was to select a model for the simulation of GPS data that gives a good description of the Ionosphere's nature with a high degree of accuracy in computing the Ionospheric delay that yields to better-simulated data. A new model developed by the author based on IGS global Ionospheric maps. A comparison

  18. State-Resolved Quantum Dynamics of Photodetachment of HCO2(-)/DCO2(-) on an Accurate Global Potential Energy Surface.

    PubMed

    Zou, Lindong; Li, Jun; Wang, Hui; Ma, Jianyi; Guo, Hua

    2015-07-16

    Full-dimensional quantum dynamics studies of the photodetachment of HCO2(-) and DCO2(-) are reported using a wave-packet method on an accurate global potential energy surface of the neutral HOCO/HCO2 system. The calculated photoelectron spectra reproduced both the positions and widths of the main HCO2 and DCO2 peaks observed in experiment. Specifically, both the (2)A1 and (2)B2 resonance peaks of the neutral radicals were identified in our simulations thanks to the adiabatic PES that captures both the (2)A1 and (2)B2 minima. The narrow widths and isotope effect of the lowest resonances are indicative of tunneling-facilitated predissociation. Furthermore, the dissociation product CO2 was found to be excited in both its symmetric stretching and bending modes, which are coupled via a strong Fermi resonance, but rotationally cold, in good agreement with the recent photoelectron-photodetachment coincidence experiments. PMID:25607218

  19. Fast and accurate global multiphase arrival tracking: the irregular shortest-path method in a 3-D spherical earth model

    NASA Astrophysics Data System (ADS)

    Huang, Guo-Jiao; Bai, Chao-Ying; Greenhalgh, Stewart

    2013-09-01

    The traditional grid/cell-based wavefront expansion algorithms, such as the shortest path algorithm, can only find the first arrivals or multiply reflected (or mode converted) waves transmitted from subsurface interfaces, but cannot calculate the other later reflections/conversions having a minimax time path. In order to overcome the above limitations, we introduce the concept of a stationary minimax time path of Fermat's Principle into the multistage irregular shortest path method. Here we extend it from Cartesian coordinates for a flat earth model to global ray tracing of multiple phases in a 3-D complex spherical earth model. The ray tracing results for 49 different kinds of crustal, mantle and core phases show that the maximum absolute traveltime error is less than 0.12 s and the average absolute traveltime error is within 0.09 s when compared with the AK135 theoretical traveltime tables for a 1-D reference model. Numerical tests in terms of computational accuracy and CPU time consumption indicate that the new scheme is an accurate, efficient and a practical way to perform 3-D multiphase arrival tracking in regional or global traveltime tomography.

  20. Bio-optical data integration based on a 4 D database system approach

    NASA Astrophysics Data System (ADS)

    Imai, N. N.; Shimabukuro, M. H.; Carmo, A. F. C.; Alcantara, E. H.; Rodrigues, T. W. P.; Watanabe, F. S. Y.

    2015-04-01

    Bio-optical characterization of water bodies requires spatio-temporal data about Inherent Optical Properties and Apparent Optical Properties which allow the comprehension of underwater light field aiming at the development of models for monitoring water quality. Measurements are taken to represent optical properties along a column of water, and then the spectral data must be related to depth. However, the spatial positions of measurement may differ since collecting instruments vary. In addition, the records should not refer to the same wavelengths. Additional difficulty is that distinct instruments store data in different formats. A data integration approach is needed to make these large and multi source data sets suitable for analysis. Thus, it becomes possible, even automatically, semi-empirical models evaluation, preceded by preliminary tasks of quality control. In this work it is presented a solution, in the stated scenario, based on spatial - geographic - database approach with the adoption of an object relational Database Management System - DBMS - due to the possibilities to represent all data collected in the field, in conjunction with data obtained by laboratory analysis and Remote Sensing images that have been taken at the time of field data collection. This data integration approach leads to a 4D representation since that its coordinate system includes 3D spatial coordinates - planimetric and depth - and the time when each data was taken. It was adopted PostgreSQL DBMS extended by PostGIS module to provide abilities to manage spatial/geospatial data. It was developed a prototype which has the mainly tools an analyst needs to prepare the data sets for analysis.

  1. Bio-optical observations of the 2004 Labrador Sea phytoplankton bloom

    NASA Astrophysics Data System (ADS)

    Strutton, Peter G.; Martz, Todd R.; Degrandpre, Michael D.; McGillis, Wade R.; Drennan, William M.; Boss, Emmanuel

    2011-11-01

    A unique time series of moored bio-optical measurements documented the 2004 spring-summer bloom in the southern Labrador Sea. In situ and satellite chlorophyll data show that chlorophyll levels in the 2004 bloom were at the upper end of those typically observed in this region. Satellite chlorophyll and profiling float temperature/salinity data show that the main bloom, which typically peaks in June/July, is often preceded by ephemeral mixed layer shoaling and a lesser, short-lived bloom in May; this was the case in 2004. The particulate backscatter to beam attenuation ratio (bbp[470 nm]/Cp[660 nm]) showed peaks in the relative abundance of small particles at bloom initiation and during the decline of the bloom, while larger particles dominated during the bloom. Chlorophyll/Cp and bbp/chlorophyll were correlated with carbon export and dominated by changes in the pigment per cell associated with lower light levels due to enhanced attenuation of solar radiation during the bloom. An NPZ (nutrients, phytoplankton, zooplankton) model captured the phytoplankton bloom and an early July peak in zooplankton. Moored acoustic Doppler current profiler (ADCP) data showed an additional mid-June peak in zooplankton biomass which was attributed to egg-laying copepods. The data reported here represent one of the few moored time series of Cp, bbp and chlorophyll extending over several months in an open ocean region. Interpretation of data sets such as this will become increasingly important as these deployments become more commonplace via ocean observing systems. Moreover, these data contribute to the understanding of biological-physical coupling in a biogeochemically important, yet poorly studied region.

  2. Monsoon variability of ultraviolet radiation (UVR) attenuation and bio-optical factors in the Asian tropical coral-reef waters

    NASA Astrophysics Data System (ADS)

    Mizubayashi, Keiko; Kuwahara, Victor S.; Segaran, Thirukanthan C.; Zaleha, Kassim; Effendy, A. W. M.; Kushairi, M. R. M.; Toda, Tatsuki

    2013-07-01

    The East coast of Peninsular Malaysia is strongly influenced by the North-East (NE) monsoon, and may significantly influence the optical environment of coral-reef ecosystems. However, our knowledge of temporal variability, including episodic events, of environmental factors in Asian tropical regions is still limited. The objectives of this study were to (1) observe temporal variability in ultraviolet radiation (UVR) and photosynthetically active radiation (PAR) attenuation and (2) determine the bio-optical factors regulating the optical environment in shallow coral-reef waters. Downwelling UVR and PAR irradiance and in situ bio-optical factors were measured monthly near Bidong Island on the East coast of Peninsular Malaysia from June 2010 to June 2011. The NE monsoon was recognized between November 2010 and January 2011. The highest diffuse attenuation coefficient at 305 nm was 2.05 ± 0.03 m-1 in a coral-reef area on December 2010. The most significant bio-optical factor at 305, 380, 440 nm during the NE monsoon season was CDOM (89 ± 8% at 305 nm, 84 ± 9% at 380 nm and 49 ± 17% at 440 nm). All UVR attenuation coefficients showed significant correlations with the CDOM absorption coefficients (aCDOM). CDOM with relatively low S275-295 during the NE monsoon season (0.0177 ± 0.0020 nm-1) suggests terrestrial sources, which is also supported by the correlation between salinity and aCDOM(305). A significant correlation between S275-295 and the carbon specific absorbance coefficient (a*(305)) suggest the potential to measure DOC optically in these waters. The high CDOM during the NE monsoon season may have an important role to reduce harmful UVR exposure reaching benthic communities.

  3. Microbial screening for quinolones residues in cow milk by bio-optical method.

    PubMed

    Appicciafuoco, Brunella; Dragone, Roberto; Frazzoli, Chiara; Bolzoni, Giuseppe; Mantovani, Alberto; Ferrini, Anna Maria

    2015-03-15

    The use of antibiotics on lactating cows should be monitored for the possible risk of milk contamination with residues. Accordingly, Maximum Residue Levels (MRLs) are established by the European Commission to guarantee consumers safety. As pointed out by Dec 2002/657/EC, screening is the first step in the strategy for antibiotic residue control, thus playing a key role in the whole control procedure. However, current routine screening methods applied in milk chain still fail to detect residues of quinolones at concentrations of interest. This paper reports the findings of a new bio-optical method for the screening of quinolones residues in bovine milk, based on E. coli ATCC 11303 growth inhibition. The effect of blank and spiked cow milk samples (aliquots equivalents to 0.8%, v/v) is evaluated in Mueller Hinton Broth (MHb) and MHb enriched with MgSO4 2% (MHb-Mg) inoculated with the test strain at the concentration of 10(4)CFU/mL. The presence of quinolones inhibits the cellular growth in MHb, while this effect is neutralized in MHb-Mg allowing both detection and presumptive identification of quinolones. Growth of the test strain is monitored at 37 °C in a Bioscreen C automated system, and Optical Density (OD) at 600 nm is recorded every 10 min after shaking for 10s. Growth curves (OD vs. time) of E. coli ATCC 11303 are assessed in milk samples, with and without quinolones, and their differences in terms of ΔOD (ΔOD600nm=ODMHb-Mg-ODMHb) are calculated. The presence of quinolones is detected by the cellular growth inhibition (OD vs time, none increase in the value OD) and presumptively identified through the increase of the slope of ΔOD600nm curve (ΔOD vs. time), after about 3h of incubation. The detection limit for ciprofloxacin and enrofloxacin is at the level of MRL, for marbofloxacin is at 2-fold the MRL whereas for danofloxacin is at 4-fold the MRL. Although the sensitivity of the method could be further improved and the procedure automated, it is a

  4. An accurate global ab initio potential energy surface for the X {sup 1}A{sup '} electronic state of HOBr

    SciTech Connect

    Peterson, Kirk A

    2000-09-15

    A global, analytical potential energy surface for the ground electronic state of HOBr has been determined using highly correlated multireference configuration interaction wave functions and explicit basis set extrapolations of large correlation consistent basis sets. The ab initio data have been fit to an analytical functional form that accurately includes both the HOBr and HBrO minima, as well as all dissociation asymptotes. Small adjustments to this surface are made based on the limited experimental data available and by indirectly taking into account the effects of spin-orbit coupling on the OH+Br dissociation channel. Vibrational energy levels are calculated variationally for both HOBr and HBrO up to the OH+Br dissociation limit using a truncation/recoupling method. The HOBr isomer is calculated to contain 708 bound vibrational energy levels, while the HBrO minimum lies above the OH+Br dissociation limit but is calculated to have 74 ''quasibound,'' localized eigenstates. Infrared intensities for all of these vibrational transitions are also calculated using MRCI dipole moment functions. The assignment of the HOBr states is complicated by strong stretch-bend resonances even at relatively low energies. In contrast to the HOCl case, these state mixings made it particularly difficult to assign the relatively intense OH overtone bands above v{sub 1}=2. The vibrational density of states of HOBr at the OH+Br dissociation limit is determined to be 0.16 states/cm-1. Comparisons to recent work on HOCl using similar methods are made throughout. (c) 2000 American Institute of Physics.

  5. An Accurate Global Ab Initio Potential Energy Surface for the X(1)A' Electronic State of HOBr

    SciTech Connect

    Peterson, Kirk A.

    1999-12-01

    A global, analytical potential energy surface for the ground electronic state of HOBr has been determined using highly correlated multireference configuration interaction wave functions and explicit basis set extrapolations of large correlation consistent basis sets. The ab initio data have been fit to an analytical functional form that accurately includes both the HOBr and HBrO minima, as well as all dissociation asymptotes. Small adjustments to this surface are made based on the limited experimental data available and by indirectly taking into account the effects of spin-orbit coupling on the OH+Br dissociation channel. Vibrational energy levels are calculated variationally for both HOBr and HBrO up to the OH+Br dissociation limit using a truncation-recoupling method. The HOBr isomer is calculated to contain 708 bound vibrational energy levels, while the HBrO minimum lies above the OH+Br dissociation limit but is calculated to have 74 quasibound, localized eigenstates. Infrared intensities for all of these vibrational transitions are also calculated using MRCI dipole moment functions. The assignment of the HOBr states is complicated by strong stretch-bend resonances even at relatively low energies. In contrast to the HOCl case, these state mixings made it particularly difficult to assign the relatively intense OH overtone bands above v1=2. The vibrational density of states of HOBr at the OH+Br dissociation limit is determined to be 0.16 states/cm-1. Comparisons to recent work on HOCl using similar methods are made throughout.

  6. Using bio-optical parameters as a tool for detecting changes in the phytoplankton community (SW Portugal)

    NASA Astrophysics Data System (ADS)

    Goela, Priscila C.; Icely, John; Cristina, Sónia; Danchenko, Sergei; Angel DelValls, T.; Newton, Alice

    2015-12-01

    Upwelling events off the Southwest coast of Portugal can trigger phytoplankton blooms that are important for the fisheries and aquaculture sectors in this region. However, climate change scenarios forecast fluctuations in the intensity and frequency of upwelling events, thereby potentially impacting these sectors. Shifts in the phytoplankton community were analysed from the end of 2008 until the beginning of 2012 by examining the bio-optical properties of the water column, namely the absorption coefficients for phytoplankton, non-algal particles and coloured dissolved organic matter (CDOM). The phytoplankton community was assessed by microscopy, with counts from an inverted microscope, and by chemotaxonomic methodologies, using pigment concentrations determined by High-Performance Liquid Chromatography (HPLC). Results both from microscopy and from chemotaxonomic methods showed a shift from diatom dominance related to bloom conditions matching upwelling events, to small flagellate dominance related to no-bloom conditions matching relaxation of upwelling. During bloom conditions, light absorption from phytoplankton increased markedly, while non-algal particles and CDOM absorption remained relatively constant. The dynamics of CDOM in the study area was attributed to coastal influences rather than from phytoplankton origin. Changes in phytoplankton biomass and consequent alterations in phytoplankton absorption coefficients were attributed to upwelling regimes in the area. Bio-optical parameters can contribute to environmental monitoring of coastal and oceanic waters, which in the case of the European Union, involves the implementation of the Water Framework, Marine Strategy Framework and Marine Spatial Planning Directives.

  7. Bio-optical and physical variability in the subarctic North Atlantic Ocean during the spring of 1989

    NASA Technical Reports Server (NTRS)

    Dickey, T.; Marra, J.; Stramska, M.; Langdon, C.; Granata, T.; Plueddemann, A.; Weller, R.; Yoder, J.

    1994-01-01

    A unique set of physical, bio-optical, and meteorological observations were made from a mooring located in the open ocean south of Iceland (59 deg 29.5 min N, 20 deg 49.8 min W) from April 13 to June 12 1989. The present measurements are apparently the first to resolve the rapid transition to springtime physical and biological conditions at such a high latitude site. Our data were collected with bio-optical and physical moored systems every few minutes. The abrupt onset of springtime stratification was observed with the mixed layer shoaling from approximately 550 m to approximately 50 m in approximately 5 days. During this period a major phytoplankton bloom occurred with a tenfold increase in near-surface chlorophyll concentration in less than 3 weeks. Our statistical analysis indicates that the velocity shear in the upper layer is driven primarily by local wind stress. Mesoscale variability is also apparent from these and concurrent airborne oceangraphic lidar observations. Our complementary modeling results suggest that the near-surface layer may be reasonably well described by a one-dimensional model and that the spring bloom was initiated during incipient near-surface restratification.

  8. Accurate and efficient modeling of global seismic wave propagation for an attenuative Earth model including the center

    NASA Astrophysics Data System (ADS)

    Toyokuni, Genti; Takenaka, Hiroshi

    2012-06-01

    We propose a method for modeling global seismic wave propagation through an attenuative Earth model including the center. This method enables accurate and efficient computations since it is based on the 2.5-D approach, which solves wave equations only on a 2-D cross section of the whole Earth and can correctly model 3-D geometrical spreading. We extend a numerical scheme for the elastic waves in spherical coordinates using the finite-difference method (FDM), to solve the viscoelastodynamic equation. For computation of realistic seismic wave propagation, incorporation of anelastic attenuation is crucial. Since the nature of Earth material is both elastic solid and viscous fluid, we should solve stress-strain relations of viscoelastic material, including attenuative structures. These relations represent the stress as a convolution integral in time, which has had difficulty treating viscoelasticity in time-domain computation such as the FDM. However, we now have a method using so-called memory variables, invented in the 1980s, followed by improvements in Cartesian coordinates. Arbitrary values of the quality factor (Q) can be incorporated into the wave equation via an array of Zener bodies. We also introduce the multi-domain, an FD grid of several layers with different grid spacings, into our FDM scheme. This allows wider lateral grid spacings with depth, so as not to perturb the FD stability criterion around the Earth center. In addition, we propose a technique to avoid the singularity problem of the wave equation in spherical coordinates at the Earth center. We develop a scheme to calculate wavefield variables on this point, based on linear interpolation for the velocity-stress, staggered-grid FDM. This scheme is validated through a comparison of synthetic seismograms with those obtained by the Direct Solution Method for a spherically symmetric Earth model, showing excellent accuracy for our FDM scheme. As a numerical example, we apply the method to simulate seismic

  9. Chlorophyll-a concentration estimation with three bio-optical algorithms: correction for the low concentration range for the Yiam Reservoir, Korea

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bio-optical algorithms have been applied to monitor water quality in surface water systems. Empirical algorithms, such as Ritchie (2008), Gons (2008), and Gilerson (2010), have been applied to estimate the chlorophyll-a (chl-a) concentrations. However, the performance of each algorithm severely degr...

  10. Bio-optical characteristics of a red tide induced by Mesodinium rubrum in the Cariaco Basin, Venezuela

    NASA Astrophysics Data System (ADS)

    Guzmán, Laurencia; Varela, Ramón; Muller-Karger, Frank; Lorenzoni, Laura

    2016-08-01

    The bio-optical changes of the water induced by red tides depend on the type of organism present, and the spectral characterization of such changes can provide useful information on the organism, abundance and distribution. Here we present results from the bio-optical characterization of a non-toxic red tide induced by the autotrophic ciliate Mesodinium rubrum. Particle absorption was high [ap(440) = 1.78 m- 1], as compared to measurements done in the same region [ap(440) = 0.09 ± 0.06 m- 1], with detrital components contributing roughly 11% [ad(440) = 0.19 m- 1]. The remainder was attributed to absorption by phytoplankton pigments [aph(440) = 1.60 m- 1]. These aph values were ~ 15 times higher than typical values for these waters. High chlorophyll a concentrations were also measured (52.73 μg L- 1), together with alloxanthin (9.52 μg L- 1) and chlorophyll c (6.25 μg L- 1). This suite of pigment is typical of the algal class Cryptophyceae, from which Mesodinium obtains its chloroplasts. Remote sensing reflectance showed relatively low values [Rrs(440) = 0.0007 sr- 1], as compared to other Rrs values for the region under high bloom conditions [Rrs(440) = 0.0028 sr- 1], with maxima at 388, 484, 520, 596 and 688 nm. Based on the low reflection in the green-yellow, as compared to other red tides, we propose a new band ratio [Rrs(688)/Rrs(564)] to identify blooms of this particular group of organisms.

  11. Phytoplankton blooms in the Patagonian shelf-break and vicinities: bio-optical signature and performance of ocean color algorithms

    NASA Astrophysics Data System (ADS)

    Garcia, C. A.; Ferreira, A.; Dogliotti, A. I.; Tavano, V. M.; High Latitude Oceanography Group-GOAL

    2011-12-01

    The PATagonia EXperiment (PATEX) is a Brazilian research project, which has the overall objective of characterizing the environmental constraints, phytoplankton assemblages, primary production rates, bio-optical characteristics, and air-sea CO2 fluxes waters along the Argentinean shelf-break during austral spring and summer. A set of seven PATEX cruises has been conducted from 2004 to 2009 (total of 189 CTD stations) covering a broad region, in waters whose surface chlorophyll-a concentration (chla) varied from 0.10 to 22.30 mg m-3. This wide range of phytoplankton biomass reflected several stages of the phytoplankton blooms with relative higher chlorophyll associated to microplankton (picoplankton and/or nanoplankton) dominance during the spring (later summer) cruises in the shelf-break blooms. A special cruise (PATEX 5) was specially designed for sampling a coccolithophorid bloom in the Patagonia inner shelf (Garcia et al, 2011, JGR, 116, C03025). Overall, distinct efficiencies in absorption and scattering properties were observed due to differences in the algal cell size and pigment composition. Cluster analysis performed on both chla-specific absorption and scattering coefficients has shown the relative contributions by each of three cell-size classes. A hierarchical cluster analysis was also applied to "in situ" hyperspectral remote sensing reflectance spectra in order to classify the whole spectra set into coherent groups. Three spectrally distinct classes were well defined and they are significantly associated chla range. NASA OC4v6 chlorophyll algorithm has shown a relatively good performance when combining bio-optical data from all cruises (r2=0.78, slope of 0.86 and intercept of 0.03), with a positive bias (Mean Relative Percentage Difference, RPD=11.53%). The impact of chlorophyll-specific absorption and scattering coefficients on the performance of ocean empirical algorithms is also accessed.

  12. Bio-Optical Properties of the Arabian Sea as Determined by In Situ and Sea WiFS Data

    NASA Technical Reports Server (NTRS)

    Trees, Charles C.

    1997-01-01

    The overall objective of this work was to characterize optical and fluorescence properties in the euphotic zone during two British Ocean Flux Study (BOFS) Arabian Sea cruises. This was later expanded in 1995 to include three U.S. JGOFS Arabian Sea Cruises. The region was to be divided into one or more "bio-optical provinces," within each of which a single set of regression models was to be developed to relate the vertical distribution of irradiance attenuation and normalized fluorescence (SF and NF) to remote sensing reflectance and diffuse attenuation coefficient. The working hypothesis was that over relatively large spatial and temporal scales, the vertical profiles of bio-optical properties were predictable. The specific technical objectives were: (1) To characterize the vertical distribution of the inherent and apparent optical properties by measuring downwelling and upwelling irradiances, upwelling radiances, scalar irradiance of PAR, and beam transmissions at each station - from these data, spectral diffuse attenuation coefficients, irradiance reflectances, remote sensing reflectances, surface-leaving radiances and beam attenuation coefficients were determined; (2) To characterize the spectral absorption of total particulate, detrital, and dissolved organic material at each station from discrete water samples; (3) To describe the vertical distribution of photoadaptive properties in the water column by measuring profiles of stimulated (SF) and natural (NF) fluorescence and examining relationships between SF and NF as a function of diffuse optical depth, pigment biomass and primary productivity; and (4) To establish locally derived, in-water algorithms relating remote sensing reflectance spectra to diffuse attenuation coefficients, phytoplankton pigment concentrations and primary productivity, through intercomparisons with in situ measurements, for application to SeaWiFS data.

  13. Water mass bio-optical properties in the Monterey Bay region: Fluorescence-based inference of shifts in phytoplankton photophysiology

    NASA Astrophysics Data System (ADS)

    Jolliff, J. K.; Gould, R. W., Jr.; Penta, B.; Teague, W. J.; DeRada, S.; Chavez, F. P.; Arnone, R. A.

    2012-07-01

    A physical and bio-optical field survey of the Monterey Bay area was conducted during May-June 2008. The combined bio-optical and physical data may be summarized as a transition between two end-member states during the late spring to summer upwelling season: (1) the mesotrophic, nanoflagellate-dominated, low-salinity surface waters (chlorophyll-a ˜ 0.5-2 mg m-3; S < 33.4) of the California Current and (2) the eutrophic, diatomaceous, higher salinity surface waters (chlorophyll-a > 2 mg m-3; S > 33.8) of Monterey Bay and adjacent continental shelf areas. High-resolution and collocated spectrophotometric, fluorometric and CTD data obtained from a towed platform indicated low-salinity subarctic-origin surface waters intruded into Monterey Bay on 4 June. The dark in vivo fluorometry (IVF) phytoplankton response normalized to particle absorption at 676 nm (the apparent fluorescence efficiency, AFE) was nearly fourfold larger in this water mass type compared to higher salinity surface waters more typical of Monterey Bay. The collocated fluorescence and optical data were then used to estimate in situ irradiance values and determine apparent light saturation intensities (I'k) based on the remarkably consistent AFE water column inflection points. I'kvalues retrieved from the low-salinity surface waters were approximately half those obtained over the continental shelf. An analysis of concomitant HPLC data, in addition to historical data for the region, suggest these observed fluorescence trends may be indicative of taxon-specific variation in photophysiology. Specifically, the subarctic water mass-associated pelagic nanoflagellate group likely possesses a fundamentally different photosynthetic architecture than large diatoms prototypical of coastal upwelling regimes.

  14. HubAlign: an accurate and efficient method for global alignment of protein–protein interaction networks

    PubMed Central

    Hashemifar, Somaye; Xu, Jinbo

    2014-01-01

    Motivation: High-throughput experimental techniques have produced a large amount of protein–protein interaction (PPI) data. The study of PPI networks, such as comparative analysis, shall benefit the understanding of life process and diseases at the molecular level. One way of comparative analysis is to align PPI networks to identify conserved or species-specific subnetwork motifs. A few methods have been developed for global PPI network alignment, but it still remains challenging in terms of both accuracy and efficiency. Results: This paper presents a novel global network alignment algorithm, denoted as HubAlign, that makes use of both network topology and sequence homology information, based upon the observation that topologically important proteins in a PPI network usually are much more conserved and thus, more likely to be aligned. HubAlign uses a minimum-degree heuristic algorithm to estimate the topological and functional importance of a protein from the global network topology information. Then HubAlign aligns topologically important proteins first and gradually extends the alignment to the whole network. Extensive tests indicate that HubAlign greatly outperforms several popular methods in terms of both accuracy and efficiency, especially in detecting functionally similar proteins. Availability: HubAlign is available freely for non-commercial purposes at http://ttic.uchicago.edu/∼hashemifar/software/HubAlign.zip Contact: jinboxu@gmail.com Supplementary information: Supplementary data are available at Bioinformatics online. PMID:25161231

  15. The Architecture and Utility of SeaBASS: the SeaWiFS Bio-optical Archive and Storage System

    NASA Astrophysics Data System (ADS)

    Werdell, P.; Bailey, S. W.; Fargion, G.; McClain, C.

    2001-12-01

    The accumulation and evaluation of in situ data is a critical aspect of both satellite ocean color sensor validation and algorithm development. NASA's Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Sensor Intercomparison and Merger for Biological and Oceanic Studies (SIMBIOS) Projects designed the SeaWiFS Bio-optical Archive and Storage System (SeaBASS) to be a local repository of radiometric, phytoplankton pigment, and other oceanographic and atmospheric data, collected using well-defined and consistent measurement protocols. These data have been used by the SIMBIOS Project to validate SeaWiFS, Ocean Color and Temperature Scanner (OCTS), and Modular Optoelectronic Scanner (MOS) data products, to develop and evaluate bio-optical algorithms used to generate such products, for data merger studies, and to characterize the calibration history and stability of the field instruments used to build validation data sets. Data archived in SeaBASS were collected using a number of instrument packages on a variety of different platforms. The archive consists of an organized directory structure where physical data files and documentation are stored and a relational database system for managing and controlling these data and metadata. A series of World Wide Web-based search engines provide the user community direct access to data files, metadata, and geophysical data products. Additionally, other online utilities are available for generating maps and plots of data archived in SeaBASS. Historically, to protect the publication rights of contributors' data and to limit user-support to active participants, access to SeaBASS has been limited to contributing researchers and to members of the SIMBIOS and other NASA-affiliated Science Teams. As of August 2001, however, data collected prior to December 31, 1999 are available to the public at large. These data are available online and via the National Oceanographic Data Center. This report elaborates on the architecture of SeaBASS and

  16. Bio-Optical Measurements in Upwelling Ecosystems in Support of SIMBIOS. Chapter 4

    NASA Technical Reports Server (NTRS)

    Chavez, Francisco P.; Strutton, Peter G.; Kuwahara, Victor S.; Mahoney, Kevin L.; Drake, Eric

    2003-01-01

    The upwelling region of the equatorial Pacific Ocean, which spans one quarter of the earth s circumference, strongly impacts global biogeochemistry. This upwelling system has significant implications for global CO2 fluxes (Tans et al., 1990; Takahashi et al., 1997; Feely et al., 1999), as well as primary and secondary production (Chavez and Barber, 1987; Chavez and Toggweiler, 1995; Chavez et al., 1996; Dugdale and Wilkerson, 1998; Chavez et al., 1999; Strutton and Chavez, 2000). In addition, the region represents a vast oceanic (case 1) region over which validation data for SeaWiFS are needed. This project consists of an optical mooring program and cruise-based measurements focused on measuring biological and chemical variability in the equatorial Pacific and obtaining validation data for SeaWiFS.

  17. The structure of thermohaline and bio-optical fields in the surface layer of the Kara Sea in September 2011

    NASA Astrophysics Data System (ADS)

    Zavialov, P. O.; Izhitskiy, A. S.; Osadchiev, A. A.; Pelevin, V. V.; Grabovskiy, A. B.

    2015-07-01

    We present data of measurements of thermohaline and bio-optical fields in the surface layer of the Kara Sea carried out in September 2012, during the 59th cruise of the R.V Akademik Mstislav Keldysh. Measurements were performed during vessel motion along the expedition route using a pump-through CTD system (temperature and salinity) and UV fluorescent lidar (concentrations of chlorophyll, total suspended matter, and dissolved organic matter) with a high spatial resolution (about 10-100 m). Detailed sea-area distribution maps of the above parameters are presented, frontal zones are detected, T, S diagrams for the surface water layer are constructed, and basic water types are identified. It is shown that Ob-Yenisei freshwater runoff is a main factor affecting properties of the surface layer. In the second part of this paper, a numerical model of the dynamics of continental runoff in the Kara Sea is suggested. Model experiments were carried out under real wind conditions of August-September 2011 (NCAR/NCEP reanalysis); the model was validated on the basis of in situ data collected during the cruise.

  18. Bio-optical profile data report: Southern California Bight Study (SCB2-29) R/V Robert G. Sproul, 20-25 August 1988

    NASA Technical Reports Server (NTRS)

    Collins, Donald J.; Tran, An Van

    1990-01-01

    Time series measurements of the incident surface downwelling irradiance and vertical profiles of the bio-optical properties of the ocean were studied during the 29th cruise of the Southern California Bight Study (SCBS) during the period of August 20-25, 1988. A summary of these data is presented to permit investigators an overview of the data collected. The data are available in digital form for scientific investigators.

  19. SeaWiFS technical report series. Volume 20: The SeaWiFS bio-optical archive and storage system (SeaBASS), part 1

    NASA Technical Reports Server (NTRS)

    Hooker, Stanford B. (Editor); Mcclain, Charles R.; Firestone, James K.; Westphal, Todd L.; Yeh, Eueng-Nan; Ge, Yuntao; Firestone, Elaine R.

    1994-01-01

    This document provides an overview of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Bio-Optical Archive and Storage System (SeaBASS), which will serve as a repository for numerous data sets of interest to the SeaWiFS Science Team and other approved investigators in the oceanographic community. The data collected will be those data sets suitable for the development and evaluation of bio-optical algorithms which include results from SeaWiFS Intercalibration Round-Robin Experiments (SIRREXs), prelaunch characterization of the SeaWiFS instrument by its manufacturer -- Hughes/Santa Barbara Research Center (SBRC), Marine Optical Characterization Experiment (MOCE) cruises, Marine Optical Buoy (MOBY) deployments and refurbishments, and field studies of other scientists outside of NASA. The primary goal of the data system is to provide a simple mechanism for querying the available archive and requesting specific items, while assuring that the data is made available only to authorized users. The design, construction, and maintenance of SeaBASS is the responsibility of the SeaWiFS Calibration and Validation Team (CVT). This report is concerned with documenting the execution of this task by the CVT and consists of a series of chapters detailing the various data sets involved. The topics presented are as follows: 1) overview of the SeaBASS file architecture, 2) the bio-optical data system, 3) the historical pigment database, 4) the SIRREX database, and 5) the SBRC database.

  20. Accurate modeling of spectral fine-structure in Earth radiance spectra measured with the Global Ozone Monitoring Experiment.

    PubMed

    van Deelen, Rutger; Hasekamp, Otto P; Landgraf, Jochen

    2007-01-10

    We present what we believe to be a novel approach to simulating the spectral fine structure (<1 nm) in measurements of spectrometers such as the Global Ozone Monitoring Experiment (GOME). GOME measures the Earth's radiance spectra and daily solar irradiance spectra from which a reflectivity spectrum is commonly extracted. The high-frequency structures contained in such a spectrum are, apart from atmospheric absorption, caused by Raman scattering and by a shift between the solar irradiance and the Earth's radiance spectrum. Normally, an a priori high-resolution solar spectrum is used to simulate these structures. We present an alternative method in which all the required information on the solar spectrum is retrieved from the GOME measurements. We investigate two approaches for the spectral range of 390-400 nm. First, a solar spectrum is reconstructed on a fine spectral grid from the GOME solar measurement. This approach leads to undersampling errors of up to 0.5% in the modeling of the Earth's radiance spectra. Second, a combination of the solar measurement and one of the Earth's radiance measurement is used to retrieve a solar spectrum. This approach effectively removes the undersampling error and results in residuals close to the GOME measurement noise of 0.1%. PMID:17268571

  1. A compact and accurate semi-global potential energy surface for malonaldehyde from constrained least squares regression

    SciTech Connect

    Mizukami, Wataru Tew, David P.; Habershon, Scott

    2014-10-14

    We present a new approach to semi-global potential energy surface fitting that uses the least absolute shrinkage and selection operator (LASSO) constrained least squares procedure to exploit an extremely flexible form for the potential function, while at the same time controlling the risk of overfitting and avoiding the introduction of unphysical features such as divergences or high-frequency oscillations. Drawing from a massively redundant set of overlapping distributed multi-dimensional Gaussian functions of inter-atomic separations we build a compact full-dimensional surface for malonaldehyde, fit to explicitly correlated coupled cluster CCSD(T)(F12*) energies with a root mean square deviations accuracy of 0.3%–0.5% up to 25 000 cm{sup −1} above equilibrium. Importance-sampled diffusion Monte Carlo calculations predict zero point energies for malonaldehyde and its deuterated isotopologue of 14 715.4(2) and 13 997.9(2) cm{sup −1} and hydrogen transfer tunnelling splittings of 21.0(4) and 3.2(4) cm{sup −1}, respectively, which are in excellent agreement with the experimental values of 21.583 and 2.915(4) cm{sup −1}.

  2. Aerial extent, composition, bio-optics and biogeochemistry of a massive under-ice algal bloom in the Arctic

    NASA Astrophysics Data System (ADS)

    Balch, W. M.; Bowler, B. C.; Lubelczyk, L. C.; Stevens, M. W.

    2014-07-01

    It has been long thought that coccolithophores are a minor component of the phytoplankton assemblage in Arctic waters, with diatoms typically being more dominant. Little is known about how the phytoplankton communities will change, however, as the Arctic warms. We participated in the 2011 Impacts of Climate on EcoSystems and Chemistry of the Arctic Pacific Environment (ICESCAPE) cruise to the western Arctic, performing a combination of discrete measurements (microscopy, calcification, particulate inorganic carbon (PIC), particulate organic carbon (POC), biogenic silica (BSi)) plus continuous surface bio-optical measurements (absorption, scattering, backscattering and acid-labile backscattering; the latter specific for coccolithophores). Here, we report bio-optical and coccolithophore observations from the massive under-ice algal bloom originally described in Arrigo et al. (2012). The most intense portions of the bloom were centered in cold Winter Water and there was evidence for nitrate drawdown in the top 10-20 m with strong penetration of silicate rich water into the surface waters. Surface chlorophyll a and particulate absorption at 440 nm approached 30 μg L-1 and 1.0 m-1, respectively. Particulate absorption of detritus (ap at 412 nm) was highly correlated to ap at 440 nm associated with chlorophyll a and slopes of the absorption spectrum showed that both dissolved and particulate absorption at 412 nm exceeded that at 440 nm, with slopes, Sg, of 0.01 nm-1. Colored dissolved organic matter fluorescence (FDOM) was high in the bloom but the relative fluorescence yields were low, characteristic of phytoplankton-produced FDOM (as opposed to terrestrially-produced FDOM). Coccolithophore backscattering was elevated in the under-ice bloom, but it only accounted for 10% of the total particle backscattering, relatively low compared to typical subpolar waters further to the south. Total particle scattering was significantly elevated in the under-ice bloom (values of

  3. An optical water type framework for selecting and blending retrievals from bio-optical algorithms in lakes and coastal waters.

    PubMed

    Moore, Timothy S; Dowell, Mark D; Bradt, Shane; Verdu, Antonio Ruiz

    2014-03-01

    Bio-optical models are based on relationships between the spectral remote sensing reflectance and optical properties of in-water constituents. The wavelength range where this information can be exploited changes depending on the water characteristics. In low chlorophyll-a waters, the blue/green region of the spectrum is more sensitive to changes in chlorophyll-a concentration, whereas the red/NIR region becomes more important in turbid and/or eutrophic waters. In this work we present an approach to manage the shift from blue/green ratios to red/NIR-based chlorophyll-a algorithms for optically complex waters. Based on a combined in situ data set of coastal and inland waters, measures of overall algorithm uncertainty were roughly equal for two chlorophyll-a algorithms-the standard NASA OC4 algorithm based on blue/green bands and a MERIS 3-band algorithm based on red/NIR bands-with RMS error of 0.416 and 0.437 for each in log chlorophyll-a units, respectively. However, it is clear that each algorithm performs better at different chlorophyll-a ranges. When a blending approach is used based on an optical water type classification, the overall RMS error was reduced to 0.320. Bias and relative error were also reduced when evaluating the blended chlorophyll-a product compared to either of the single algorithm products. As a demonstration for ocean color applications, the algorithm blending approach was applied to MERIS imagery over Lake Erie. We also examined the use of this approach in several coastal marine environments, and examined the long-term frequency of the OWTs to MODIS-Aqua imagery over Lake Erie. PMID:24839311

  4. Satellite Ocean Color Data Merging Using a Bio-optical model: A Path for Earth Science Data Records ?

    NASA Astrophysics Data System (ADS)

    Maritorena, S.; Siegel, D. A.; Hembise Fanton D'Andon, O.; Mangin, A.; Frew, J.; Nelson, N.

    2009-12-01

    The characteristics and benefits of ocean color merged data sets created using a semi-analytical model and the normalized water-leaving radiance observations from the SeaWiFS, MODIS-AQUA and MERIS ocean color missions are presented. Merged data products are coalesced from multiple mission observations into a single data product with better spatial and temporal coverage than the individual missions. Using the data from SeaWiFS, MODIS-AQUA and MERIS for the 2002-2009 time period, the average daily coverage of a merged product is ~25% of the world ocean which is nearly twice that of any single mission’s observations. The frequency at which a particular area is sampled from space is also greatly improved in merged data as some areas can be sampled as frequently as 64% of the time (in days). The merged data are validated through matchup analyses and by comparing them to the data sets obtained from individual missions. Further, a complete error budget was developed which accounts for uncertainty associated with input water-leaving radiances, the bio-optical model and uncertainty estimates for the output products (i.e. the chlorophyll concentration, the combined dissolved and detrital absorption coefficient and the particulate backscattering coefficient). These merged products and their uncertainties at each pixel were developed within the NASA MEASURES (http://wiki.icess.ucsb.edu/measures/index.php/Main_Page) and ESA GlobColour (http://www.globcolour.info/) projects and are available to the scientific community. The merging approach has many potential benefits for the creation of Earth Science Data Records from satellite ocean color observations.

  5. An optical water type framework for selecting and blending retrievals from bio-optical algorithms in lakes and coastal waters

    PubMed Central

    Moore, Timothy S.; Dowell, Mark D.; Bradt, Shane; Verdu, Antonio Ruiz

    2014-01-01

    Bio-optical models are based on relationships between the spectral remote sensing reflectance and optical properties of in-water constituents. The wavelength range where this information can be exploited changes depending on the water characteristics. In low chlorophyll-a waters, the blue/green region of the spectrum is more sensitive to changes in chlorophyll-a concentration, whereas the red/NIR region becomes more important in turbid and/or eutrophic waters. In this work we present an approach to manage the shift from blue/green ratios to red/NIR-based chlorophyll-a algorithms for optically complex waters. Based on a combined in situ data set of coastal and inland waters, measures of overall algorithm uncertainty were roughly equal for two chlorophyll-a algorithms—the standard NASA OC4 algorithm based on blue/green bands and a MERIS 3-band algorithm based on red/NIR bands—with RMS error of 0.416 and 0.437 for each in log chlorophyll-a units, respectively. However, it is clear that each algorithm performs better at different chlorophyll-a ranges. When a blending approach is used based on an optical water type classification, the overall RMS error was reduced to 0.320. Bias and relative error were also reduced when evaluating the blended chlorophyll-a product compared to either of the single algorithm products. As a demonstration for ocean color applications, the algorithm blending approach was applied to MERIS imagery over Lake Erie. We also examined the use of this approach in several coastal marine environments, and examined the long-term frequency of the OWTs to MODIS-Aqua imagery over Lake Erie. PMID:24839311

  6. The Use of Accurate Mass Tags based upon High-Throughput Fourier Transform Ion Cyclotron Resonance Mass Spectrometry for Global Proteomic Characterization

    SciTech Connect

    Camp, David G.; Smith, Richard D.

    2004-07-30

    In this review, we describe the technological basis and progress towards a new global proteomics strategy that uses peptide accurate mass measurements augmented by information from separations (e.g. LC retention times) to provide large improvements in sensitivity, dynamic range, comprehensiveness and throughput. The use of ?accurate mass and time? (AMT) tags serves to eliminate the need for routine MS/MS measurements [#4109]. As the case study, we use our own research efforts to illustrate the role of AMTs within the broader context of a state-of-the-art proteomics effort. Our strategy exploits high-resolution capillary LC separations combined with Fourier transform ion cyclotron resonance mass spectrometry (FTICR). AMTs represent peptide biomarkers and can be used to confidently identify proteins based on the high mass measurement accuracy provided by FTICR combined with LC elution times. Once identified using MS/MS, these biomarkers provide the foundation for subsequent high throughput studies using only AMT tags to identify and quantify the proteins expressed within a cell system. Key attractions of this approach include the feasibility of completely automated high confidence protein identifications, extensive proteome coverage, and the capability for exploiting stable-isotope labeling methods for high precision abundance measurements [#4019]. Additional developments described in this review include methods for more effective coverage of membrane proteins [#4184], for dynamic range expansion of proteome measurements [#4012], and for multi-stage separations that promise to enable more focused analyses, further extend the quality of measurements, and also extend measurements to more complex proteomes.

  7. OCTS and SeaWiFS Bio-Optical Algorithm and Product Validation and Intercomparison in US Coastal Waters. Chapter 5

    NASA Technical Reports Server (NTRS)

    Brown, Christopher W.; Subramaniam, Ajit; Culver, Mary; Brock, John C.

    2001-01-01

    Monitoring the health of US coastal waters is an important goal of the National Oceanic and Atmospheric Administration (NOAA). Satellite sensors are capable of providing daily synoptic data of large expanses of the US coast. Ocean color sensors, in particular, can be used to monitor the water quality of coastal waters on an operational basis. To appraise the validity of satellite-derived measurements, such as chlorophyll concentration, the bio-optical algorithms used to derive them must be evaluated in coastal environments. Towards this purpose, over 21 cruises in diverse US coastal waters have been conducted. Of these 21 cruises, 12 have been performed in conjunction with and under the auspices of the NASA/Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project. The primary goal of these cruises has been to obtain in-situ measurements of downwelling irradiance, upwelling radiance, and chlorophyll concentrations in order to evaluate bio-optical algorithms that estimate chlorophyll concentration. In this Technical Memorandum, we evaluate the ability of five bio-optical algorithms, including the current Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) algorithm, to estimate chlorophyll concentration in surface waters of the South Atlantic Bight (SAB). The SAB consists of a variety of environments including coastal and continental shelf regimes, Gulf Stream waters, and the Sargasso Sea. The biological and optical characteristics of the region is complicated by temporal and spatial variability in phytoplankton composition, primary productivity, and the concentrations of colored dissolved organic matter (CDOM) and suspended sediment. As such, the SAB is an ideal location to test the robustness of algorithms for coastal use.

  8. Spatio-temporal Variations of Phytoplankton and Bio-optical Characteristics In Case Ii Waters: Example of The Eastern English Channel During Spring 2000

    NASA Astrophysics Data System (ADS)

    Vantrepotte, V.; Brunet, C.; Mériaux, X.; Lécuyer, E.; Vellucci, V.

    In the aim to use remote sensing technique to estimate algal biomass concentrations in surface coastal waters, it is necessary to obtain in situ information on the mesoscale phytoplankton dynamics, as well as on bio-optical properties of water masses. This step is useful to regionally validate and interpret the satellite-derived data and for lo- cal primary production modelisation. Five mesoscale cruises (BiopTel cruises) were realized in the eastern English Channel between February and October 2000, in order to study phytoplankton dynamics and bio-optical characteristics, as well as the factors controlling their seasonal variations. From the measurements realized at two depths in the water column (phytoplankton pigments by HPLC, nutrient concentrations, phyto- plankton productivity by Phyto-Pam technique, yellow substance concentrations, phy- toplankton absorption spectrum), we can define several biological provinces and their temporal succession. Fv/Fm ratio and ETR measurements (as a proxy for primary productivity) show variations according to space (different ecosystems and coastal- offshore transects) and time (season) in relation with phytoplankton quantity and quality, light and nutrient availability. Significant mesoscale relationships are found between ETR and some hydrobiological parameters. Moreover, spatio-temporal vari- ations of IOPs are highlighted. Yellow substances present their higher concentrations near the Seine and the Somme estuaries, and follow a seasonal variation characterized by two phases. From winter to early spring, they decrease in relation with the decrease of rivers runoff and then they significantly increase from early spring to summer, in relation with the increase of water temperature. Phytoplankton absorption spectrum results show a high variability in space and time, and these results are discussed in relationship with phytoplankton community composition and physiological state. Re- gional relationships between bio-optical

  9. A new bio-optical model to estimate phytoplankton primary production: An application in the eastern Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Stefanì, Chiara; Bonamano, Simone; Melchiorri, Cristiano; Piermattei, Viviana; Fani, Fabiola; Lazzara, Luigi; Marcelli, Marco

    2015-04-01

    The estimation of phytoplankton primary production provides basic input for the quantification of carbon flux in the ocean because of the strong relationship between available photosynthetic energy at the ocean surface and energy storage by algal photosynthesis. We used a new version of PhytoVFP (Variable Fluorescence Phytoplankton Production) bio-optical model to calculate phytoplankton primary production (PP) in the euphotic zone. PhytoVFP is classified as a Wavelength- and Depth-resolved (WRDR) model and is based on the implementation of photosynthetic efficiency (Fv / Fmax), measured in-situ by the PrimProd probe. An innovation of the model is the reproduction of the daily photoacclimation process by varying photosynthetic parameters (Ek, alfa and Pbmax ) along the water column as a function of stratification. The PhytoVFP model is structured into three main modules: (1) "PAR estimation ";- (2) "Photo-acclimation of marine phytoplankton"; - (3) "Phytoplankton primary production estimation". The performance of the PhytoVFP model was evaluated using PAR and 14C primary production measures collected during the SAMCA3 and SAMCA4 oceanographic cruises. The comparison between the measured and calculated radiation showed a good correlation, both in the surface and along the water column (R2 = 0.8992 in the presence, and R2 = 0.8747 in the absence, of clouds) Sensitivity tests, carried out on phie (photosynthetic quantum yield) and beta (photoinhibition parameter), allowed us to identify the best model parametrization which minimized the MAE (Mean Absolute Error). The values assigned to these parameters allowed to have a good correlation between the measured and estimated primary production values (R² = 0.808923). The results of PhytoVFP model have been also compared with its older version and the Morel (1991) model showing that the MAE of the new version is lower than the other models. The PhytoVFP model was applied on Primprod data collected during MedGOOS12 cruise

  10. Bio-optical characteristics of a phytoplankton bloom event off Baja California Peninsula (30 31°N)

    NASA Astrophysics Data System (ADS)

    Barocio-León, Óscar A.; Millán-Núñez, Roberto; Santamaría-del-Ángel, Eduardo; Gonzalez-Silvera, Adriana; Trees, Charles C.; Orellana-Cepeda, Elizabeth

    2008-03-01

    A phytoplankton bloom was detected in the Southern California Current System, off the Baja California Peninsula (Mexico) on June 2003 with chlorophyll- a concentration (TChl a) of 10.13 mg m -3. Two stations (D1 and D2) were sampled on June 24, and D2 was resampled 6 days later; chlorophyll- a concentration had decreased by about one half. LAC MODIS-Chl a images were obtained and showed the spread of the bloom on the day after sampling. The phytoplankton community consisted primarily of dinoflagellate temporary cysts, mainly at the surface and at 5 m in station D1. Two Pseudo-nitzschia species ( P. australis, P. seriata) were also very abundant. Samples from the bloom had a specific phytoplankton absorption coefficient ( aph*(λ)) lower than the rest of the samples. Values varied from 0.0186 to 0.0455 m 2 mg -1 for aph*(440) and from 0.0092 to 0.0294 m 2 mg -1 for aph*(675), with ratios aph*(440): aph*(675) ranging from 0.99 to 2.20. These low ratios were associated with the combined effect of packaging, and with the relatively high ratios of fucoxanthin, peridinin, diadinoxanthin and chlorophyll- c2 to TChl a. Samples from the surface and 5 m depth at station D1 had higher ratios of Perid:TChl a (0.12-0.32) than the rest of the samples, suggesting that cysts have similar Perid:TChl a as free-living dinoflagellates. An unusual absorption spectrum with a broad maximum around 480-500 nm was associated with the high proportion of cysts and diatoms. The slope of the spectra between 443 and 488 nm was a good index to differentiate bloom samples containing high proportions of dinoflagellate temporary cysts. Further investigation of the absorption properties of dinoflagellate cysts is needed in order to detect these waters by remote sensing. Although much work is still necessary to understand and explain the bio-optical properties of a bloom, the present study is the first assessment off the Baja California coast to simultaneously consider aspects such as absorption

  11. Bio-optical characterization of offshore NW Mediterranean waters: CDOM contribution to the absorption budget and diffuse attenuation of downwelling irradiance

    NASA Astrophysics Data System (ADS)

    Pérez, Gonzalo L.; Galí, Martí; Royer, Sarah-Jeanne; Sarmento, Hugo; Gasol, Josep M.; Marrasé, Cèlia; Simó, Rafel

    2016-08-01

    We investigated the peculiar bio-optical characteristics of the Mediterranean Sea focusing on the spectral diffuse attenuation coefficient [Kd (λ)] and its relationship with chlorophyll a concentration (Chl a), complemented with measurements of light absorption by chromophoric dissolved organic matter (CDOM) and the optical properties of particulate material. The non-water absorption budget showed that CDOM was the largest contributor in the 300-600 nm range (>60% of the absorption at 443 nm in the euphotic layer), increasing to 80% within the first optical depth (FOD). This translated into CDOM accounting for >50% of KdBio (λ) (the irradiance attenuation coefficient caused by all non-water absorptions) between 320 and 555 nm and throughout both layers (FOD and euphotic). Indeed, we tested three Chl a-based bio-optical models and all three underestimated Kd (λ), evidencing the importance of CDOM beside Chl a to fully account for light attenuation. The Morel & Maritorena (2001) model (M&M 01) underestimated Kd (λ) in the UV and blue spectral regions within the FOD layer, showing lower differences with increasing wavelengths. The Morel et al. (2007a) model (BGS 07) also underestimated Kd (λ) in the FOD layer, yet it performed much better in the 380-555 nm range. In the euphotic layer, the Morel (1988) model (JGR 88) underestimated Kd (λ) showing higher differences at 412 and 443 nm and also performed better at higher wavelengths. Observed euphotic layer depths (Z1%) were 28 m shallower than those predicted with the M&M 01 empirical relationship, further highlighting the role of CDOM in the bio-optical peculiarity of Mediterranean Sea. In situ measurements of the CDOM index (Φ), an indicator of the deviation of the CDOM-Chl a average relationship for Case 1 waters, gave a mean of 5.9 in the FOD, consistent with simultaneous estimates from MODIS (4.8±0.4). The implications of the bio-optical anomaly for ecological and biogeochemical inferences in the

  12. Mesoscale and seasonal bio-optical properties variability in coastal waters using the example of the eastern English Channel during Spring, 2000

    NASA Astrophysics Data System (ADS)

    Vantrepotte, Vincent; Brunet, Christophe; Meriaux, Xavier; Lecuyer, Eric; Dilligeard, Eric; Santer, Richard P.

    2003-05-01

    Remote sensed chlorophyll α (chlα) maps are useful to proceed to phytoplankton dynamics study and primary production modelization in coastal waters. However, chlα remote sensing depend on the bio-optical characteristics of waters masses which are site-specific and highly variable according to space and time in coastal waters. In order to study the seasonal variability of phytoplankton and bio-optic parameters as well as the factors controlling their spatio-temporal distributions, five mesoscale cruises (BIOPTEL) were carried out in the eastern English Channel during the spring 2000 (between February and October). Phytoplankton absorption spectrum showed a high variability according to space and time due to the algal community composition and the physiological state. Considering these scales of variation, a local model was defined. The variability of the two other components of marine absorption: yellow substances and non algal particles are also presented and related to exogenous parameters such as river flow, temperature and hydrodynamism. Furthermore, in order to appreciate how important are the local IOPs (Inherent Optical Properties) variability on AOPs (Apparent Optical Properties) restitution a sensitivity analysis was realized. In the frame of biomass estimation, marine reflectance were simulated considering the local absorption coefficients rather than the standard ones.

  13. Seasonal variations of bio-optical properties and their interrelationships observed by Bio-Argo floats in the subpolar North Atlantic

    NASA Astrophysics Data System (ADS)

    Xing, Xiaogang; Claustre, Hervé; Uitz, Julia; Mignot, Alexandre; Poteau, Antoine; Wang, Haili

    2014-10-01

    Based on in situ data sets collected using two Bio-Argo floats deployed in the subpolar North Atlantic from June 2008 to May 2010, the present study focuses on the seasonal variability of three bio-optical properties, i.e., chlorophyll-a concentration ([Chla]), particle backscattering coefficient at 532 nm (bbp(532)), and particle beam attenuation coefficient at 660 nm (cp(660)). In addition, the interrelationships among these properties are examined. Our results show that: (1) [Chla], bbp(532) and cp(660) are largely well coupled with each other in the upper layer, all being minimum in mid-winter (January) and maximum in summer; (2) the backscattering coefficient presents an abrupt increase in late summer in the Icelandic Basin, likely due to a large contribution of coccolithophores following the diatom spring bloom; (3) the intercorrelations between the three bio-optical properties are basically consistent with previous studies; (4) seasonal variation in the of [Chla] to cp(660) ratio exhibits a clear light-dependence, most likely due to the phytoplankton photoacclimation.

  14. Accurate ab initio-based adiabatic global potential energy surface for the 2(2)A" state of NH2 by extrapolation to the complete basis set limit.

    PubMed

    Li, Y Q; Ma, F C; Sun, M T

    2013-10-21

    A full three-dimensional global potential energy surface is reported first time for the title system, which is important for the photodissociation processes. It is obtained using double many-body expansion theory and an extensive set of accurate ab initio energies extrapolated to the complete basis set limit. Such a work can be recommended for dynamics studies of the N((2)D) + H2 reaction, a reliable theoretical treatment of the photodissociation dynamics and as building blocks for constructing the double many-body expansion potential energy surface of larger nitrogen/hydrogen containing systems. In turn, a preliminary theoretical study of the reaction N((2)D)+H2(X(1)Σg (+))(ν=0,j=0)→NH(a(1)Δ)+H((2)S) has been carried out with the method of quasi-classical trajectory on the new potential energy surface. Integral cross sections and thermal rate constants have been calculated, providing perhaps the most reliable estimate of the integral cross sections and the rate constants known thus far for such a reaction. PMID:24160511

  15. Six-dimensional quantum dynamics of dissociative chemisorption of H2 on Co(0001) on an accurate global potential energy surface.

    PubMed

    Jiang, Bin; Hu, Xixi; Lin, Sen; Xie, Daiqian; Guo, Hua

    2015-09-28

    Cobalt is a widely used catalyst for many heterogeneous reactions, including the Fischer-Tropsch (FT) process, which converts syngas (H2 and CO) to higher hydrocarbons. As a result, a better understanding of the key chemical steps on the Co surface, such as the dissociative chemisorption of H2 as an initial step of the FT process, is of fundamental importance. Here, we report an accurate full-dimensional global potential energy surface for the dissociative chemisorption of H2 on the rigid Co(0001) surface constructed from more than 3000 density functional theory points. The high-fidelity potential energy surface was obtained using the permutation invariant polynomial-neural network method, which preserves both the permutation symmetry of H2 and translational symmetry of the Co(0001) surface. The reaction path features a very low barrier on the top site. Full-dimensional quantum dynamical calculations provide insights into the dissociation dynamics and influence of the initial vibrational, rotational, and orientational degrees of freedom. PMID:26286861

  16. Accurate ab initio-based adiabatic global potential energy surface for the 22A″ state of NH2 by extrapolation to the complete basis set limit

    NASA Astrophysics Data System (ADS)

    Li, Y. Q.; Ma, F. C.; Sun, M. T.

    2013-10-01

    A full three-dimensional global potential energy surface is reported first time for the title system, which is important for the photodissociation processes. It is obtained using double many-body expansion theory and an extensive set of accurate ab initio energies extrapolated to the complete basis set limit. Such a work can be recommended for dynamics studies of the N(2D) + H2 reaction, a reliable theoretical treatment of the photodissociation dynamics and as building blocks for constructing the double many-body expansion potential energy surface of larger nitrogen/hydrogen containing systems. In turn, a preliminary theoretical study of the reaction N(^2D)+H_2(X^1Σ _g^+)(ν =0,j=0)rArr NH(a^1Δ )+H(^2S) has been carried out with the method of quasi-classical trajectory on the new potential energy surface. Integral cross sections and thermal rate constants have been calculated, providing perhaps the most reliable estimate of the integral cross sections and the rate constants known thus far for such a reaction.

  17. Variability Of Bio-Optical Parameters Of The SE Baltic Sea Coastal Waters Based On In Situ And Satellite Data

    NASA Astrophysics Data System (ADS)

    Vaiciute, Diana; Bresciani, Mariano; Matta, Erica; Braga, Frederica; Bucas, Martynas

    2013-12-01

    In our study we present validation activities associated with satellite MERIS image processing aimed at estimating chlorophyll a (chl a), coloured dissolved organic matter (CDOM) and total suspended matter (TSM) in the Lithuanian Baltic Sea coastal waters. Eight MERIS full-resolution Level 1b images, acquired during late spring and summer 2010, were processed using five, neural network-based processors for optically Case 2 coastal and inland waters: FUB, C2R, Eutrophic, Boreal, and standard MERIS Level 2. Results showed that the FUB processor provided the most accurate estimates of the concentration of chl a and TSM. In situ CDOM absorption was most accurately estimated using the Boreal processor. SE Baltic Sea at the Lithuanian coast is connected to the hypereutrophic Curonian Lagoon. The outflow region remains oligohaline with temporary and irregular salinity fluctuations from 0 to 7(8) PSU mainly driven by wind. Over the salinity gradient we observed patchy distribution of optically active constituents that may cause the changes of optical water properties. In order to understand the impact of the lagoon waters outflow to the coastal region on the validation results, during the summer 2012 inherent and apparent optical properties were measured and remote sensing reflectance was analysed over the investigation region.

  18. Accurate high level ab initio-based global potential energy surface and dynamics calculations for ground state of CH{sub 2}{sup +}

    SciTech Connect

    Li, Y. Q.; Zhang, P. Y.; Han, K. L.

    2015-03-28

    A global many-body expansion potential energy surface is reported for the electronic ground state of CH{sub 2}{sup +} by fitting high level ab initio energies calculated at the multireference configuration interaction level with the aug-cc-pV6Z basis set. The topographical features of the new global potential energy surface are examined in detail and found to be in good agreement with those calculated directly from the raw ab initio energies, as well as previous calculations available in the literature. In turn, in order to validate the potential energy surface, a test theoretical study of the reaction CH{sup +}(X{sup 1}Σ{sup +})+H({sup 2}S)→C{sup +}({sup 2}P)+H{sub 2}(X{sup 1}Σ{sub g}{sup +}) has been carried out with the method of time dependent wavepacket on the title potential energy surface. The total integral cross sections and the rate coefficients have been calculated; the results determined that the new potential energy surface can both be recommended for dynamics studies of any type and as building blocks for constructing the potential energy surfaces of larger C{sup +}/H containing systems.

  19. Brazilian inland water bio-optical dataset to support carbon budget studies in reservoirs as well as anthropogenic impacts in Amazon floodplain lakes: Preliminary results

    NASA Astrophysics Data System (ADS)

    Barbosa, C.; Novo, E.; Ferreira, R.; Carvalho, L.; Cairo, C.; Lopes, F.; Stech, J.; Alcantara, E.

    2015-04-01

    This work presents ongoing efforts and preliminary results for building a dataset that represents the first and most comprehensive bio-optical information available on Brazilian inland waters to support the development of remote sensing algorithms for monitoring aquatic systems. From 2012 to 2014 optical and limnological data was gathered along thirteen field campaigns in five Brazilian reservoirs, in an irrigation and domestic water supply reservoir located in semi-arid northeast of the country and in Amazonian floodplain lakes, thus covering the diversity of Brazilian inland waters. At each site 20 stations, on average, were sampled to acquire profiles of the following optical variables: absorption, attenuation, scattering, and backscattering coefficients and radiances/irradiances spectra above and in-water. Alongside these measurements, water samples were collected for determining concentrations of chlorophyll-a (Chl-a), Total Suspended Solid (TSS), Total Dissolved Carbon (TDC) and its organic/inorganic fractions, CDOM absorption, phytoplankton specific absorption [aph*] and Non-Algal Particles absorption [aNAP*]. Preliminary results show that Chl-a concentrations ranged from 0.6 to 243μg/L in reservoirs and 0.90 to 92μg/L in Amazonian lakes, while TSS concentrations ranged from 0.3 to 31mg/L in reservoirs and 0.5 to 162mg/L in Amazonian lakes. In situ beam attenuation coefficients ranged from 1.4 to 16m-1 in reservoirs and 12.5 to 38m-1 in Amazonian lakes, while diffuse attenuation coefficients of downwelling irradiance over the Photosynthetically Active Radiation (Kd(PAR)) extended from 0.35 to 4.5m-1 in reservoirs and 1.69 to 13.30m-1 in Amazonian lakes. Our research group is building this dataset anticipating future demands for algorithm validation regarding OLI/Landsat8 data and ESA Sentinel missions to be launched as of 2015.

  20. Bio-Optical Properties and Ocean Color Algorithms for Coastal Waters Influenced by the Mississippi River During a Cold Front Passage

    NASA Technical Reports Server (NTRS)

    D'Sa Eurico J.; Miller, Richard L.; DelCastillo, Carlos

    2006-01-01

    During the passage of a cold front in March 2002, bio-optical properties examined in coastal waters impacted by the Mississippi River indicated westward advective flows and increasing river discharge containing a larger nonalgal particle content contributed significantly to surface optical variability. A comparison of seasonal data from three cruises indicated spectral models of absorption and scattering to be generally consistent with other coastal environments, while their parameterization in terms of chlorophyll a concentration (Chl) showed seasonal variability. The exponential slope of the colored dissolved organic matter (CDOM) averaged 0.0161 plus or minus 0.00054 per nanometer, and for nonalgal absorption it averaged 0.011 per nanometer with deviations from general trends observed due to anomalous water properties. Although the phytoplankton specific absorption coefficients varied over a wide range (0.02 to 0.1 square meters (mg Chl) sup -1)) being higher in offshore surface waters, values of phytoplankton absorption spectra at the SeaWiFS wavebands were highly correlated to modeled values. The normalized scattering spectral shapes and the mean spectrum were in agreement to observations in other coastal waters, while the backscattering ratios were on average lower in phytoplankton dominated surface waters (0.0101 plus or minus 0.002) and higher in near-bottom waters (0.0191 plus or minus 0.0045) with low Chl. Average percent differences in remote sensing reflectance R (sub rs) derived form modeled and in-eater radiometric measurements were highest in the blue wavebands (52%) and at sampling stations with a ore stratified water column. Estimates of Chl and CDOM absorption derived from SeaWiFS images generated using regional empirical algorithms were highly correlated to in situ data.

  1. New Chemical, Bio-Optical and Physical Observations of Upper Ocean Response to the Passage of a Mesoscale Eddy Off Bermuda

    NASA Technical Reports Server (NTRS)

    McNeil, J. D.; Jannasch, H. W.; Dickey, T.; McGillicuddy, Dennis J., Jr.; Brzezinski, M.; Sakamoto, C. M.

    1999-01-01

    A mesoscale eddy advected across the Bermuda Testbed Mooring site over a 30-day period centered on July 14, 1995. Temperature and current measurements along with biogeochemical measurements were used to characterize the biological response of the upper ocean associated with the introduction of nitrate into the euphotic layer due to the doming of isotherms associated with the eddy. Complementary shipboard data showed an anomalous water mass, which extended from a depth of approximately 50 to 1000 m, manifesting as a cold surface expression and warm anomaly at depth. Although mesoscale eddies are frequently observed in the Sargasso Sea, the present observations are particularly unique because of the high-temporal-resolution measurements of the new instrumentation deployed on the mooring. Analyzers that measure nitrate plus nitrite were placed at depths of 80 and 200 m and bio-optical sensors were located at depths of 20, 35, 45, 71, and 86 m. Peak nitrate values of nearly 3.0 micro-M at 80 m and chlorophyll a values of 1.4 mg/cubic m at 71 m were observed, a well as a 25- to 30-meter shoaling of the 1% light level depth. A Doppler shift from the inertial period (22.8 hours) to 25.2 hours was observed in several time series records due to the movement of the eddy across the mooring. Inertial pumping brought cold, nutrient-rich waters farther into the euphotic zone than would occur solely by isothermal lifting. Silicic acid was depleted to undetectable levels owing to the growth of diatoms within the eddy. The chlorophyll a values associated with the eddy appear to be the largest recorded during the eight years of the ongoing US JGOFS Bermuda Atlantic Time Series Study program.

  2. New Chemical, Bio-Optical and Physical Observations of Upper Ocean Response to the Passage of a Mesoscale Eddy off Bermuda

    NASA Technical Reports Server (NTRS)

    McNeil, J. D.; Jannasch, H. W.; Dickey, T.; McGillicuddy, D.; Brzekinski, M.; Sakamoto, C. M.

    1999-01-01

    A mesoscale eddy advected across the Bermuda Testbed Mooring site over a 30-day period centered on July 14, 1995. Temperature and current measurements along with biogeochemical measurements were used to characterize the biological response of the upper ocean associated with the introduction of nitrate into the euphoric layer due to the doming of isotherms associated with the eddy. Complementary shipboard data showed an anomalous water mass, which extended from a depth of approximately 50 to 1000 m, manifesting as a cold surface expression and warm anomaly at depth. Although mesoscale eddies are frequently observed in the Sargasso Sea, the present observations are particularly unique because of the high-temporal-resolution measurements of the new instrumentation deployed on the mooring. Analyzers that measure nitrate plus nitrite were placed at depths of 80 and 200 m and bio-optical sensors were located at depths of 20, 35, 45, 71, and 86 m. Peak nitrate values of nearly 3.0 microns at 80 m and chlorophyll alpha values of 1.4 mg/cu m at 71 m were observed, as well as a 25- to 30-meter shoaling of the 1% light level depth. A Doppler shift from the inertial period (22.8 hours) to 25.2 hours was observed in several time series records due to the movement of the eddy across the mooring. Inertial pumping brought cold, nutrient-rich waters farther into the euphotic zone than would occur solely by isothermal lifting. Silicic acid was depleted to undetectable levels owing to the growth of diatoms within the eddy. The chlorophyll alpha values associated with the eddy appear to be the largest recorded during the 8 years of the ongoing U.S. JGOFS Bermuda Atlantic Time Series Study (BATS) program.

  3. Validation of Surface Bio-Optical Properties in the Gulf of Maine as a Means for Improving Satellite Primary Production Estimates. Chapter 4

    NASA Technical Reports Server (NTRS)

    Balch, William M.

    2001-01-01

    One of the greatest challenges in providing sea-truth data for various ocean color sensors is climatology. This is particularly true in the Gulf of Maine since it is cloudy and foggy more than it is clear; the climatology shows on average, about one in four to five days has clear skies with clear days slightly more frequent in the late summer and early fall. Our strategy has been to use a ship of opportunity where one has choice of the sampling days. This provides much better flexibility to sample during clear periods with good satellite coverage. Our Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) contract has been to use the M/S Scotia Prince ferry as a ship of opportunity, running between Portland, Maine and Yarmouth, NS. Measurements include continuous, surface, along-track fluorescence, two independent measures of backscattering, total light scattering, absorption, beam attenuation, above-water remote sensing reflectance, calcite-dependent light scattering, temperature, and salinity. Expendable bathythermography (XBT) drops allow acquisition of vertical temperature information, useful for defining isopycnal slope, which affects primary production. These data are comparable to a previous program from early 1982, where a ship of opportunity program (SOOP) was run on the truck ferry, M/V Marine Evangeline, which ran along the same transect. These surface data were combined with satellite-derived sea surface temperature fields to examine the Maine coastal current. Unfortunately, this program stopped in 1982. The ongoing SIMBIOS results will dovetail nicely with the previous work (which also had Coastal Zone Color Scanner (CZCS) coverage) for looking at any long-term changes in the Gulf of Maine hydrography, bio-optics, and biogeochemistry.

  4. Accurate market price formation model with both supply-demand and trend-following for global food prices providing policy recommendations.

    PubMed

    Lagi, Marco; Bar-Yam, Yavni; Bertrand, Karla Z; Bar-Yam, Yaneer

    2015-11-10

    Recent increases in basic food prices are severely affecting vulnerable populations worldwide. Proposed causes such as shortages of grain due to adverse weather, increasing meat consumption in China and India, conversion of corn to ethanol in the United States, and investor speculation on commodity markets lead to widely differing implications for policy. A lack of clarity about which factors are responsible reinforces policy inaction. Here, for the first time to our knowledge, we construct a dynamic model that quantitatively agrees with food prices. The results show that the dominant causes of price increases are investor speculation and ethanol conversion. Models that just treat supply and demand are not consistent with the actual price dynamics. The two sharp peaks in 2007/2008 and 2010/2011 are specifically due to investor speculation, whereas an underlying upward trend is due to increasing demand from ethanol conversion. The model includes investor trend following as well as shifting between commodities, equities, and bonds to take advantage of increased expected returns. Claims that speculators cannot influence grain prices are shown to be invalid by direct analysis of price-setting practices of granaries. Both causes of price increase, speculative investment and ethanol conversion, are promoted by recent regulatory changes-deregulation of the commodity markets, and policies promoting the conversion of corn to ethanol. Rapid action is needed to reduce the impacts of the price increases on global hunger. PMID:26504216

  5. Accurate market price formation model with both supply-demand and trend-following for global food prices providing policy recommendations

    PubMed Central

    Lagi, Marco; Bar-Yam, Yavni; Bertrand, Karla Z.; Bar-Yam, Yaneer

    2015-01-01

    Recent increases in basic food prices are severely affecting vulnerable populations worldwide. Proposed causes such as shortages of grain due to adverse weather, increasing meat consumption in China and India, conversion of corn to ethanol in the United States, and investor speculation on commodity markets lead to widely differing implications for policy. A lack of clarity about which factors are responsible reinforces policy inaction. Here, for the first time to our knowledge, we construct a dynamic model that quantitatively agrees with food prices. The results show that the dominant causes of price increases are investor speculation and ethanol conversion. Models that just treat supply and demand are not consistent with the actual price dynamics. The two sharp peaks in 2007/2008 and 2010/2011 are specifically due to investor speculation, whereas an underlying upward trend is due to increasing demand from ethanol conversion. The model includes investor trend following as well as shifting between commodities, equities, and bonds to take advantage of increased expected returns. Claims that speculators cannot influence grain prices are shown to be invalid by direct analysis of price-setting practices of granaries. Both causes of price increase, speculative investment and ethanol conversion, are promoted by recent regulatory changes—deregulation of the commodity markets, and policies promoting the conversion of corn to ethanol. Rapid action is needed to reduce the impacts of the price increases on global hunger. PMID:26504216

  6. Accomplishments of the MUSICA project to provide accurate, long-term, global and high-resolution observations of tropospheric {H2O,δD} pairs - a review

    NASA Astrophysics Data System (ADS)

    Schneider, Matthias; Wiegele, Andreas; Barthlott, Sabine; González, Yenny; Christner, Emanuel; Dyroff, Christoph; García, Omaira E.; Hase, Frank; Blumenstock, Thomas; Sepúlveda, Eliezer; Mengistu Tsidu, Gizaw; Takele Kenea, Samuel; Rodríguez, Sergio; Andrey, Javier

    2016-07-01

    In the lower/middle troposphere, {H2O,δD} pairs are good proxies for moisture pathways; however, their observation, in particular when using remote sensing techniques, is challenging. The project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) addresses this challenge by integrating the remote sensing with in situ measurement techniques. The aim is to retrieve calibrated tropospheric {H2O,δD} pairs from the middle infrared spectra measured from ground by FTIR (Fourier transform infrared) spectrometers of the NDACC (Network for the Detection of Atmospheric Composition Change) and the thermal nadir spectra measured by IASI (Infrared Atmospheric Sounding Interferometer) aboard the MetOp satellites. In this paper, we present the final MUSICA products, and discuss the characteristics and potential of the NDACC/FTIR and MetOp/IASI {H2O,δD} data pairs. First, we briefly resume the particularities of an {H2O,δD} pair retrieval. Second, we show that the remote sensing data of the final product version are absolutely calibrated with respect to H2O and δD in situ profile references measured in the subtropics, between 0 and 7 km. Third, we reveal that the {H2O,δD} pair distributions obtained from the different remote sensors are consistent and allow distinct lower/middle tropospheric moisture pathways to be identified in agreement with multi-year in situ references. Fourth, we document the possibilities of the NDACC/FTIR instruments for climatological studies (due to long-term monitoring) and of the MetOp/IASI sensors for observing diurnal signals on a quasi-global scale and with high horizontal resolution. Fifth, we discuss the risk of misinterpreting {H2O,δD} pair distributions due to incomplete processing of the remote sensing products.

  7. Accurate ab initio-based adiabatic global potential energy surface for the 2{sup 2}A″ state of NH{sub 2} by extrapolation to the complete basis set limit

    SciTech Connect

    Li, Y. Q.; Ma, F. C.; Sun, M. T.

    2013-10-21

    A full three-dimensional global potential energy surface is reported first time for the title system, which is important for the photodissociation processes. It is obtained using double many-body expansion theory and an extensive set of accurate ab initio energies extrapolated to the complete basis set limit. Such a work can be recommended for dynamics studies of the N({sup 2}D) + H{sub 2} reaction, a reliable theoretical treatment of the photodissociation dynamics and as building blocks for constructing the double many-body expansion potential energy surface of larger nitrogen/hydrogen containing systems. In turn, a preliminary theoretical study of the reaction N({sup 2}D)+H{sub 2}(X{sup 1}Σ{sub g}{sup +})(ν=0,j=0)→NH(a{sup 1}Δ)+H({sup 2}S) has been carried out with the method of quasi-classical trajectory on the new potential energy surface. Integral cross sections and thermal rate constants have been calculated, providing perhaps the most reliable estimate of the integral cross sections and the rate constants known thus far for such a reaction.

  8. Grading More Accurately

    ERIC Educational Resources Information Center

    Rom, Mark Carl

    2011-01-01

    Grades matter. College grading systems, however, are often ad hoc and prone to mistakes. This essay focuses on one factor that contributes to high-quality grading systems: grading accuracy (or "efficiency"). I proceed in several steps. First, I discuss the elements of "efficient" (i.e., accurate) grading. Next, I present analytical results…

  9. Accurate monotone cubic interpolation

    NASA Technical Reports Server (NTRS)

    Huynh, Hung T.

    1991-01-01

    Monotone piecewise cubic interpolants are simple and effective. They are generally third-order accurate, except near strict local extrema where accuracy degenerates to second-order due to the monotonicity constraint. Algorithms for piecewise cubic interpolants, which preserve monotonicity as well as uniform third and fourth-order accuracy are presented. The gain of accuracy is obtained by relaxing the monotonicity constraint in a geometric framework in which the median function plays a crucial role.

  10. Accurate Finite Difference Algorithms

    NASA Technical Reports Server (NTRS)

    Goodrich, John W.

    1996-01-01

    Two families of finite difference algorithms for computational aeroacoustics are presented and compared. All of the algorithms are single step explicit methods, they have the same order of accuracy in both space and time, with examples up to eleventh order, and they have multidimensional extensions. One of the algorithm families has spectral like high resolution. Propagation with high order and high resolution algorithms can produce accurate results after O(10(exp 6)) periods of propagation with eight grid points per wavelength.

  11. Accurate measurement of time

    NASA Astrophysics Data System (ADS)

    Itano, Wayne M.; Ramsey, Norman F.

    1993-07-01

    The paper discusses current methods for accurate measurements of time by conventional atomic clocks, with particular attention given to the principles of operation of atomic-beam frequency standards, atomic hydrogen masers, and atomic fountain and to the potential use of strings of trapped mercury ions as a time device more stable than conventional atomic clocks. The areas of application of the ultraprecise and ultrastable time-measuring devices that tax the capacity of modern atomic clocks include radio astronomy and tests of relativity. The paper also discusses practical applications of ultraprecise clocks, such as navigation of space vehicles and pinpointing the exact position of ships and other objects on earth using the GPS.

  12. Accurate quantum chemical calculations

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.

    1989-01-01

    An important goal of quantum chemical calculations is to provide an understanding of chemical bonding and molecular electronic structure. A second goal, the prediction of energy differences to chemical accuracy, has been much harder to attain. First, the computational resources required to achieve such accuracy are very large, and second, it is not straightforward to demonstrate that an apparently accurate result, in terms of agreement with experiment, does not result from a cancellation of errors. Recent advances in electronic structure methodology, coupled with the power of vector supercomputers, have made it possible to solve a number of electronic structure problems exactly using the full configuration interaction (FCI) method within a subspace of the complete Hilbert space. These exact results can be used to benchmark approximate techniques that are applicable to a wider range of chemical and physical problems. The methodology of many-electron quantum chemistry is reviewed. Methods are considered in detail for performing FCI calculations. The application of FCI methods to several three-electron problems in molecular physics are discussed. A number of benchmark applications of FCI wave functions are described. Atomic basis sets and the development of improved methods for handling very large basis sets are discussed: these are then applied to a number of chemical and spectroscopic problems; to transition metals; and to problems involving potential energy surfaces. Although the experiences described give considerable grounds for optimism about the general ability to perform accurate calculations, there are several problems that have proved less tractable, at least with current computer resources, and these and possible solutions are discussed.

  13. Image Formation in Bio-optical Sensing

    NASA Astrophysics Data System (ADS)

    Miller, Eric

    2012-02-01

    Over the past two decades a number of optical sensing methods have emerged with potential to provide complementary information to traditional medical imaging modalities in application areas ranging from basic science to disease diagnosis and treatment monitoring. Though still largely in the research and development stage, modalities including diffuse optical tomography (DOT), fluorescence molecular tomography (FMT), photo-acoustic tomography (PAT), and bio-luminescence tomography (BLT) have excited much interest due to their natural functional imaging capability, their relatively low cost, and the fact that none required the use of ionizing radiation. These advantages however are tempered by a number of challenges associated with the processing of these data. Specifically, these data types all rely in one way or another on the interaction of light with tissue. The diffusive nature of this interaction inherently limits the spatial resolution of these modalities. As a result the process of forming an image is a far more delicate task than is the case with more standard imaging modalities such as X-ray computed tomography (CT). Two basic methods have been explored to address the ill-posedness of these problems in order to improve the information content in the resulting images. The optical data may be augmented either through the use of spectral diversity or by attempting to integrate optical data types with information from other modalities such as CT or MRI. Alternatively, a mathematical technique known as regularization can be used to impose physically-based constraints on the reconstruction. In this talk, I shall provide an overview of the work in my group in optical image formation within the contexts of DOT for breast cancer imaging and FMT for small animal imaging. The focus of the talk will be on methods that integrate data augmentation and mathematical regularization. In the case of FMT, we shall discuss our work in combining the optical data with information provided by CT concerning the structural distribution of tissue classes within the region of interest. Here, we have developed a number of spatially-varying regularization methods which use the CT data to help constrain the FMT reconstruction and obtain imaging results that are substantially improved over classical regularization techniques. For DOT, we have recently been considering the use of hyperspectral data sets in which information from over 100 near infrared wavelengths is made available to the processing. When combined with a regularization scheme based on parameterizing the images in a geometric manner, we believe that it will be possible to produce a standalone DOT system with spatial resolution that is today only achieved by combining DOT with e.g., CT.

  14. NNLOPS accurate associated HW production

    NASA Astrophysics Data System (ADS)

    Astill, William; Bizon, Wojciech; Re, Emanuele; Zanderighi, Giulia

    2016-06-01

    We present a next-to-next-to-leading order accurate description of associated HW production consistently matched to a parton shower. The method is based on reweighting events obtained with the HW plus one jet NLO accurate calculation implemented in POWHEG, extended with the MiNLO procedure, to reproduce NNLO accurate Born distributions. Since the Born kinematics is more complex than the cases treated before, we use a parametrization of the Collins-Soper angles to reduce the number of variables required for the reweighting. We present phenomenological results at 13 TeV, with cuts suggested by the Higgs Cross section Working Group.

  15. How to accurately bypass damage

    PubMed Central

    Broyde, Suse; Patel, Dinshaw J.

    2016-01-01

    Ultraviolet radiation can cause cancer through DNA damage — specifically, by linking adjacent thymine bases. Crystal structures show how the enzyme DNA polymerase η accurately bypasses such lesions, offering protection. PMID:20577203

  16. Accurate Evaluation of Quantum Integrals

    NASA Technical Reports Server (NTRS)

    Galant, David C.; Goorvitch, D.

    1994-01-01

    Combining an appropriate finite difference method with Richardson's extrapolation results in a simple, highly accurate numerical method for solving a Schr\\"{o}dinger's equation. Important results are that error estimates are provided, and that one can extrapolate expectation values rather than the wavefunctions to obtain highly accurate expectation values. We discuss the eigenvalues, the error growth in repeated Richardson's extrapolation, and show that the expectation values calculated on a crude mesh can be extrapolated to obtain expectation values of high accuracy.

  17. Predict amine solution properties accurately

    SciTech Connect

    Cheng, S.; Meisen, A.; Chakma, A.

    1996-02-01

    Improved process design begins with using accurate physical property data. Especially in the preliminary design stage, physical property data such as density viscosity, thermal conductivity and specific heat can affect the overall performance of absorbers, heat exchangers, reboilers and pump. These properties can also influence temperature profiles in heat transfer equipment and thus control or affect the rate of amine breakdown. Aqueous-amine solution physical property data are available in graphical form. However, it is not convenient to use with computer-based calculations. Developed equations allow improved correlations of derived physical property estimates with published data. Expressions are given which can be used to estimate physical properties of methyldiethanolamine (MDEA), monoethanolamine (MEA) and diglycolamine (DGA) solutions.

  18. Accurate thickness measurement of graphene

    NASA Astrophysics Data System (ADS)

    Shearer, Cameron J.; Slattery, Ashley D.; Stapleton, Andrew J.; Shapter, Joseph G.; Gibson, Christopher T.

    2016-03-01

    Graphene has emerged as a material with a vast variety of applications. The electronic, optical and mechanical properties of graphene are strongly influenced by the number of layers present in a sample. As a result, the dimensional characterization of graphene films is crucial, especially with the continued development of new synthesis methods and applications. A number of techniques exist to determine the thickness of graphene films including optical contrast, Raman scattering and scanning probe microscopy techniques. Atomic force microscopy (AFM), in particular, is used extensively since it provides three-dimensional images that enable the measurement of the lateral dimensions of graphene films as well as the thickness, and by extension the number of layers present. However, in the literature AFM has proven to be inaccurate with a wide range of measured values for single layer graphene thickness reported (between 0.4 and 1.7 nm). This discrepancy has been attributed to tip-surface interactions, image feedback settings and surface chemistry. In this work, we use standard and carbon nanotube modified AFM probes and a relatively new AFM imaging mode known as PeakForce tapping mode to establish a protocol that will allow users to accurately determine the thickness of graphene films. In particular, the error in measuring the first layer is reduced from 0.1-1.3 nm to 0.1-0.3 nm. Furthermore, in the process we establish that the graphene-substrate adsorbate layer and imaging force, in particular the pressure the tip exerts on the surface, are crucial components in the accurate measurement of graphene using AFM. These findings can be applied to other 2D materials.

  19. Accurate ab Initio Spin Densities

    PubMed Central

    2012-01-01

    We present an approach for the calculation of spin density distributions for molecules that require very large active spaces for a qualitatively correct description of their electronic structure. Our approach is based on the density-matrix renormalization group (DMRG) algorithm to calculate the spin density matrix elements as a basic quantity for the spatially resolved spin density distribution. The spin density matrix elements are directly determined from the second-quantized elementary operators optimized by the DMRG algorithm. As an analytic convergence criterion for the spin density distribution, we employ our recently developed sampling-reconstruction scheme [J. Chem. Phys.2011, 134, 224101] to build an accurate complete-active-space configuration-interaction (CASCI) wave function from the optimized matrix product states. The spin density matrix elements can then also be determined as an expectation value employing the reconstructed wave function expansion. Furthermore, the explicit reconstruction of a CASCI-type wave function provides insight into chemically interesting features of the molecule under study such as the distribution of α and β electrons in terms of Slater determinants, CI coefficients, and natural orbitals. The methodology is applied to an iron nitrosyl complex which we have identified as a challenging system for standard approaches [J. Chem. Theory Comput.2011, 7, 2740]. PMID:22707921

  20. Accurate Fiber Length Measurement Using Time-of-Flight Technique

    NASA Astrophysics Data System (ADS)

    Terra, Osama; Hussein, Hatem

    2016-06-01

    Fiber artifacts of very well-measured length are required for the calibration of optical time domain reflectometers (OTDR). In this paper accurate length measurement of different fiber lengths using the time-of-flight technique is performed. A setup is proposed to measure accurately lengths from 1 to 40 km at 1,550 and 1,310 nm using high-speed electro-optic modulator and photodetector. This setup offers traceability to the SI unit of time, the second (and hence to meter by definition), by locking the time interval counter to the Global Positioning System (GPS)-disciplined quartz oscillator. Additionally, the length of a recirculating loop artifact is measured and compared with the measurement made for the same fiber by the National Physical Laboratory of United Kingdom (NPL). Finally, a method is proposed to relatively correct the fiber refractive index to allow accurate fiber length measurement.

  1. GloboLakes: A global observatory of lake responses to environmental change.

    NASA Astrophysics Data System (ADS)

    Groom, Steve; Tyler, Andrew; Hunter, Peter; Spyrakos, Evangelos; Martinez-Vicente, Victor; Merchant, Chris; Cutler, Mark; Rowan, John; Dawson, Terry; Maberly, Stephen; Cavalho, Laurence; Elliot, Alex; Thackery, Stephen; Miller, Claire; Scott, Marian

    2014-05-01

    The world's freshwater ecosystems are vital components of the global biosphere, yet are vulnerable to climate and other human-induced change. There is increasing recognition that lakes play an important role in global biogeochemical cycling and provide key ecosystem services. However, our understanding of how lakes respond to environmental change at a global scale, and how this impacts on their status and function, is hampered by limited information on their chemical, physical and ecological condition. There are estimated to be over 300 million lakes globally, of which over 17,000 are greater than 10 km2 in surface area. These numbers have limited the systematic study of lake ecosystems. GloboLakes is a five-year UK research programme investigating the state of lakes and their response to climatic and other environmental drivers of change. It will establish a satellite-based observatory with archive and near-real time data processing to produce a time series of observed biogeochemical parameters and lake temperature for over 1000 lakes globally. This will be supported by linked ancillary data on climate and catchment land-use. The ability to monitor a large number of lakes consistently at high frequency and globally will facilitate a paradigm shift in our understanding of how lakes respond to environmental change at different spatial and temporal scales. A key requirement is to validate satellite retrieval algorithms and test the time-series of resulting lake properties such as chlorophyll-a by comparison with in situ data. To support the former extensive bio-optical and constituent data were taken in year 1 of the project in a number of UK lakes with a variety of trophic states. Furthermore, for wider validation activities GloboLakes has established the LIMNADES initiative to create a centralised database of ground bio-optical measurements of worldwide lakes through voluntary cooperation across the international scientific community. This presentation will

  2. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2013-07-01 2013-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  3. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  4. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2011-07-01 2011-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  5. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  6. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2012-07-01 2012-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  7. Global Aerosol Observations

    Atmospheric Science Data Center

    2013-04-19

    ... atmosphere, directly influencing global climate and human health. Ground-based networks that accurately measure column aerosol amount and ... being used to improve Air Quality Models and for regional health studies. To assess the human-health impact of chronic aerosol exposure, ...

  8. Accurate parameter estimation for unbalanced three-phase system.

    PubMed

    Chen, Yuan; So, Hing Cheung

    2014-01-01

    Smart grid is an intelligent power generation and control console in modern electricity networks, where the unbalanced three-phase power system is the commonly used model. Here, parameter estimation for this system is addressed. After converting the three-phase waveforms into a pair of orthogonal signals via the α β-transformation, the nonlinear least squares (NLS) estimator is developed for accurately finding the frequency, phase, and voltage parameters. The estimator is realized by the Newton-Raphson scheme, whose global convergence is studied in this paper. Computer simulations show that the mean square error performance of NLS method can attain the Cramér-Rao lower bound. Moreover, our proposal provides more accurate frequency estimation when compared with the complex least mean square (CLMS) and augmented CLMS. PMID:25162056

  9. Accurately Determining the Risks of Rising Sea Level

    NASA Astrophysics Data System (ADS)

    Marbaix, Philippe; Nicholls, Robert J.

    2007-10-01

    With the highest density of people and the greatest concentration of economic activity located in the coastal regions, sea level rise is an important concern as the climate continues to warm. Subsequent flooding may potentially disrupt industries, populations, and livelihoods, particularly in the long term if the climate is not quickly stabilized [McGranahan et al., 2007; Tol et al., 2006]. To help policy makers understand these risks, a more accurate description of hazards posed by rising sea levels is needed at the global scale, even though the impacts in specific regions are better known.

  10. Mill profiler machines soft materials accurately

    NASA Technical Reports Server (NTRS)

    Rauschl, J. A.

    1966-01-01

    Mill profiler machines bevels, slots, and grooves in soft materials, such as styrofoam phenolic-filled cores, to any desired thickness. A single operator can accurately control cutting depths in contour or straight line work.

  11. Remote balance weighs accurately amid high radiation

    NASA Technical Reports Server (NTRS)

    Eggenberger, D. N.; Shuck, A. B.

    1969-01-01

    Commercial beam-type balance, modified and outfitted with electronic controls and digital readout, can be remotely controlled for use in high radiation environments. This allows accurate weighing of breeder-reactor fuel pieces when they are radioactively hot.

  12. Understanding the Code: keeping accurate records.

    PubMed

    Griffith, Richard

    2015-10-01

    In his continuing series looking at the legal and professional implications of the Nursing and Midwifery Council's revised Code of Conduct, Richard Griffith discusses the elements of accurate record keeping under Standard 10 of the Code. This article considers the importance of accurate record keeping for the safety of patients and protection of district nurses. The legal implications of records are explained along with how district nurses should write records to ensure these legal requirements are met. PMID:26418404

  13. Ultraviolet radiation and bio-optics in Crater Lake, Oregon

    USGS Publications Warehouse

    Hargreaves, B.R.; Girdner, S.F.; Buktenica, M.W.; Collier, R.W.; Urbach, E.; Larson, G.L.

    2007-01-01

    Crater Lake, Oregon, is a mid-latitude caldera lake famous for its depth (594 m) and blue color. Recent underwater spectral measurements of solar radiation (300-800 nm) support earlier observations of unusual transparency and extend these to UV-B wavelengths. New data suggest that penetration of solar UVR into Crater Lake has a significant ecological impact. Evidence includes a correlation between water column chlorophyll-a and stratospheric ozone since 1984, the scarcity of organisms in the upper water column, and apparent UV screening pigments in phytoplankton that vary with depth. The lowest UV-B diffuse attenuation coefficients (K d,320) were similar to those reported for the clearest natural waters elsewhere, and were lower than estimates for pure water published in 1981. Optical proxies for UVR attenuation were correlated with chlorophyll-a concentration (0-30 m) during typical dry summer months from 1984 to 2002. Using all proxies and measurements of UV transparency, decadal and longer cycles were apparent but no long-term trend since the first optical measurement in 1896. ?? 2007 Springer Science+Business Media B.V.

  14. Bio-optical Measurement in the California Current

    NASA Technical Reports Server (NTRS)

    Mitchell, B. Greg

    2005-01-01

    We measured the optical and bio-geochemical properties during the autumn 2004 CalCOFI cruise. Calibration of in situ radiometry instruments We maintain NIST-traceable calibration of our PRR-800/8 10 radiometers. SIRREX-linked calibrations for our PRR-800/8 10 have been accomplished by Biospherical Instruments, Inc. (BSI) and SDSU Center for Hydro Optics and Remote Sensing (CHORS) since May 1993.

  15. Monitoring global vegetation

    NASA Technical Reports Server (NTRS)

    Macdonald, R. B.; Houston, A. G.; Heydorn, R. P.; Botkin, D. B.; Estes, J. E.; Strahler, A. H.

    1981-01-01

    An attempt is made to identify the need for, and the current capability of, a technology which could aid in monitoring the Earth's vegetation resource on a global scale. Vegetation is one of our most critical natural resources, and accurate timely information on its current status and temporal dynamics is essential to understand many basic and applied environmental interrelationships which exist on the small but complex planet Earth.

  16. Robust ODF smoothing for accurate estimation of fiber orientation.

    PubMed

    Beladi, Somaieh; Pathirana, Pubudu N; Brotchie, Peter

    2010-01-01

    Q-ball imaging was presented as a model free, linear and multimodal diffusion sensitive approach to reconstruct diffusion orientation distribution function (ODF) using diffusion weighted MRI data. The ODFs are widely used to estimate the fiber orientations. However, the smoothness constraint was proposed to achieve a balance between the angular resolution and noise stability for ODF constructs. Different regularization methods were proposed for this purpose. However, these methods are not robust and quite sensitive to the global regularization parameter. Although, numerical methods such as L-curve test are used to define a globally appropriate regularization parameter, it cannot serve as a universal value suitable for all regions of interest. This may result in over smoothing and potentially end up in neglecting an existing fiber population. In this paper, we propose to include an interpolation step prior to the spherical harmonic decomposition. This interpolation based approach is based on Delaunay triangulation provides a reliable, robust and accurate smoothing approach. This method is easy to implement and does not require other numerical methods to define the required parameters. Also, the fiber orientations estimated using this approach are more accurate compared to other common approaches. PMID:21096202

  17. Decadal Changes in Global Ocean Annual Primary Production

    NASA Technical Reports Server (NTRS)

    Gregg, Watson; Conkright, Margarita E.; Behrenfeld, Michael J.; Ginoux, Paul; Casey, Nancy W.; Koblinsky, Chester J. (Technical Monitor)

    2002-01-01

    The Sea-viewing Wide Field-of-View Sensor (SeaWiFS) has produced the first multi-year time series of global ocean chlorophyll observations since the demise of the Coastal Zone Color Scanner (CZCS) in 1986. Global observations from 1997-present from SeaWiFS combined with observations from 1979-1986 from the CZCS should in principle provide an opportunity to observe decadal changes in global ocean annual primary production, since chlorophyll is the primary driver for estimates of primary production. However, incompatibilities between algorithms have so far precluded quantitative analysis. We have developed and applied compatible processing methods for the CZCS, using modern advances in atmospheric correction and consistent bio-optical algorithms to advance the CZCS archive to comparable quality with SeaWiFS. We applied blending methodologies, where in situ data observations are incorporated into the CZCS and SeaWiFS data records, to provide improvement of the residuals. These re-analyzed, blended data records provide maximum compatibility and permit, for the first time, a quantitative analysis of the changes in global ocean primary production in the early-to-mid 1980's and the present, using synoptic satellite observations. An intercomparison of the global and regional primary production from these blended satellite observations is important to understand global climate change and the effects on ocean biota. Photosynthesis by chlorophyll-containing phytoplankton is responsible for biotic uptake of carbon in the oceans and potentially ultimately from the atmosphere. Global ocean annual primary decreased from the CZCS record to SeaWiFS, by nearly 6% from the early 1980s to the present. Annual primary production in the high latitudes was responsible for most of the decadal change. Conversely, primary production in the low latitudes generally increased, with the exception of the tropical Pacific. The differences and similarities of the two data records provide evidence

  18. Global Education.

    ERIC Educational Resources Information Center

    Longstreet, Wilma S., Ed.

    1988-01-01

    This issue contains an introduction ("The Promise and Perplexity of Globalism," by W. Longstreet) and seven articles dedicated to exploring the meaning of global education for today's schools. "Global Education: An Overview" (J. Becker) develops possible definitions, identifies objectives and skills, and addresses questions and issues in this…

  19. Global Science.

    ERIC Educational Resources Information Center

    Brophy, Michael

    1991-01-01

    Approaches taken by a school science department to implement a global science curriculum using a range of available resources are outlined. Problems with current curriculum approaches, alternatives to an ethnocentric curriculum, advantages of global science, and possible strategies for implementing a global science policy are discussed. (27…

  20. Global Education.

    ERIC Educational Resources Information Center

    Berkley, June, Ed.

    1982-01-01

    The articles in this collection deal with various methods of global education--education to prepare students to function as understanding and informed citizens of the world. Topics discussed in the 26 articles include: (1) the necessity of global education; (2) global education in the elementary school language arts curriculum; (3) science fiction…

  1. Global HRD.

    ERIC Educational Resources Information Center

    1997

    This document contains four papers from a symposium on global human resource development (HRD). "Globalization of Human Resource Management (HRM) in Government: A Cross-Cultural Perspective" (Pan Suk Kim) relates HRM to national cultures and addresses its specific functional aspects with a unique dimension in a global organization. "An…

  2. A highly accurate interatomic potential for argon

    NASA Astrophysics Data System (ADS)

    Aziz, Ronald A.

    1993-09-01

    A modified potential based on the individually damped model of Douketis, Scoles, Marchetti, Zen, and Thakkar [J. Chem. Phys. 76, 3057 (1982)] is presented which fits, within experimental error, the accurate ultraviolet (UV) vibration-rotation spectrum of argon determined by UV laser absorption spectroscopy by Herman, LaRocque, and Stoicheff [J. Chem. Phys. 89, 4535 (1988)]. Other literature potentials fail to do so. The potential also is shown to predict a large number of other properties and is probably the most accurate characterization of the argon interaction constructed to date.

  3. DNA barcode data accurately assign higher spider taxa.

    PubMed

    Coddington, Jonathan A; Agnarsson, Ingi; Cheng, Ren-Chung; Čandek, Klemen; Driskell, Amy; Frick, Holger; Gregorič, Matjaž; Kostanjšek, Rok; Kropf, Christian; Kweskin, Matthew; Lokovšek, Tjaša; Pipan, Miha; Vidergar, Nina; Kuntner, Matjaž

    2016-01-01

    The use of unique DNA sequences as a method for taxonomic identification is no longer fundamentally controversial, even though debate continues on the best markers, methods, and technology to use. Although both existing databanks such as GenBank and BOLD, as well as reference taxonomies, are imperfect, in best case scenarios "barcodes" (whether single or multiple, organelle or nuclear, loci) clearly are an increasingly fast and inexpensive method of identification, especially as compared to manual identification of unknowns by increasingly rare expert taxonomists. Because most species on Earth are undescribed, a complete reference database at the species level is impractical in the near term. The question therefore arises whether unidentified species can, using DNA barcodes, be accurately assigned to more inclusive groups such as genera and families-taxonomic ranks of putatively monophyletic groups for which the global inventory is more complete and stable. We used a carefully chosen test library of CO1 sequences from 49 families, 313 genera, and 816 species of spiders to assess the accuracy of genus and family-level assignment. We used BLAST queries of each sequence against the entire library and got the top ten hits. The percent sequence identity was reported from these hits (PIdent, range 75-100%). Accurate assignment of higher taxa (PIdent above which errors totaled less than 5%) occurred for genera at PIdent values >95 and families at PIdent values ≥ 91, suggesting these as heuristic thresholds for accurate generic and familial identifications in spiders. Accuracy of identification increases with numbers of species/genus and genera/family in the library; above five genera per family and fifteen species per genus all higher taxon assignments were correct. We propose that using percent sequence identity between conventional barcode sequences may be a feasible and reasonably accurate method to identify animals to family/genus. However, the quality of the

  4. DNA barcode data accurately assign higher spider taxa

    PubMed Central

    Coddington, Jonathan A.; Agnarsson, Ingi; Cheng, Ren-Chung; Čandek, Klemen; Driskell, Amy; Frick, Holger; Gregorič, Matjaž; Kostanjšek, Rok; Kropf, Christian; Kweskin, Matthew; Lokovšek, Tjaša; Pipan, Miha; Vidergar, Nina

    2016-01-01

    The use of unique DNA sequences as a method for taxonomic identification is no longer fundamentally controversial, even though debate continues on the best markers, methods, and technology to use. Although both existing databanks such as GenBank and BOLD, as well as reference taxonomies, are imperfect, in best case scenarios “barcodes” (whether single or multiple, organelle or nuclear, loci) clearly are an increasingly fast and inexpensive method of identification, especially as compared to manual identification of unknowns by increasingly rare expert taxonomists. Because most species on Earth are undescribed, a complete reference database at the species level is impractical in the near term. The question therefore arises whether unidentified species can, using DNA barcodes, be accurately assigned to more inclusive groups such as genera and families—taxonomic ranks of putatively monophyletic groups for which the global inventory is more complete and stable. We used a carefully chosen test library of CO1 sequences from 49 families, 313 genera, and 816 species of spiders to assess the accuracy of genus and family-level assignment. We used BLAST queries of each sequence against the entire library and got the top ten hits. The percent sequence identity was reported from these hits (PIdent, range 75–100%). Accurate assignment of higher taxa (PIdent above which errors totaled less than 5%) occurred for genera at PIdent values >95 and families at PIdent values ≥ 91, suggesting these as heuristic thresholds for accurate generic and familial identifications in spiders. Accuracy of identification increases with numbers of species/genus and genera/family in the library; above five genera per family and fifteen species per genus all higher taxon assignments were correct. We propose that using percent sequence identity between conventional barcode sequences may be a feasible and reasonably accurate method to identify animals to family/genus. However, the quality of

  5. Accurate pointing of tungsten welding electrodes

    NASA Technical Reports Server (NTRS)

    Ziegelmeier, P.

    1971-01-01

    Thoriated-tungsten is pointed accurately and quickly by using sodium nitrite. Point produced is smooth and no effort is necessary to hold the tungsten rod concentric. The chemically produced point can be used several times longer than ground points. This method reduces time and cost of preparing tungsten electrodes.

  6. Extremely Accurate On-Orbit Position Accuracy using TDRSS

    NASA Technical Reports Server (NTRS)

    Stocklin, Frank; Toral, Marco; Bar-Sever, Yoaz; Rush, John

    2006-01-01

    NASA is planning to launch a new service for Earth satellites providing them with precise GPS differential corrections and other ancillary information enabling decimeter level orbit determination accuracy and nanosecond time-transfer accuracy, onboard, in real-time. The TDRSS Augmentation Service for Satellites (TASS) will broadcast its message on the S-band multiple access forward channel of NASA s Tracking and Data Relay Satellite System (TDRSS). The satellite's phase array antenna has been configured to provide a wide beam, extending coverage up to 1000 km altitude over the poles. Global coverage will be ensured with broadcast from three or more TDRSS satellites. The GPS differential corrections are provided by the NASA Global Differential GPS (GDGPS) System, developed and operated by JPL. The GDGPS System employs global ground network of more than 70 GPS receivers to monitor the GPS constellation in real time. The system provides real-time estimates of the GPS satellite states, as well as many other real-time products such as differential corrections, global ionospheric maps, and integrity monitoring. The unique multiply redundant architecture of the GDGPS System ensures very high reliability, with 99.999% demonstrated since the inception of the system in early 2000. The estimated real time GPS orbit and clock states provided by the GDGPS system are accurate to better than 20 cm 3D RMS, and have been demonstrated to support sub-decimeter real time positioning and orbit determination for a variety of terrestrial, airborne, and spaceborne applications. In addition to the GPS differential corrections, TASS will provide real-time Earth orientation and solar flux information that enable precise onboard knowledge of the Earth-fixed position of the spacecraft, and precise orbit prediction and planning capabilities. TASS will also provide 5 seconds alarms for GPS integrity failures based on the unique GPS integrity monitoring service of the GDGPS System.

  7. Feedback about More Accurate versus Less Accurate Trials: Differential Effects on Self-Confidence and Activation

    ERIC Educational Resources Information Center

    Badami, Rokhsareh; VaezMousavi, Mohammad; Wulf, Gabriele; Namazizadeh, Mahdi

    2012-01-01

    One purpose of the present study was to examine whether self-confidence or anxiety would be differentially affected by feedback from more accurate rather than less accurate trials. The second purpose was to determine whether arousal variations (activation) would predict performance. On Day 1, participants performed a golf putting task under one of…

  8. Feedback about more accurate versus less accurate trials: differential effects on self-confidence and activation.

    PubMed

    Badami, Rokhsareh; VaezMousavi, Mohammad; Wulf, Gabriele; Namazizadeh, Mahdi

    2012-06-01

    One purpose of the present study was to examine whether self-confidence or anxiety would be differentially affected byfeedback from more accurate rather than less accurate trials. The second purpose was to determine whether arousal variations (activation) would predict performance. On day 1, participants performed a golf putting task under one of two conditions: one group received feedback on the most accurate trials, whereas another group received feedback on the least accurate trials. On day 2, participants completed an anxiety questionnaire and performed a retention test. Shin conductance level, as a measure of arousal, was determined. The results indicated that feedback about more accurate trials resulted in more effective learning as well as increased self-confidence. Also, activation was a predictor of performance. PMID:22808705

  9. Regional to Global Assessments of Phytoplankton Dynamics From The SeaWiFS Mission

    NASA Technical Reports Server (NTRS)

    Siegel, David; Behrenfeld, Michael; Maritorena, Stephanie; McClain, Charles R.; Antoine, David; Bailey, Sean W.; Bontempi, Paula S.; Boss, Emmanuel S.; Dierssen, Heidi M.; Doney, Scott C.; Eplee, R. E., Jr.; Evans, Robert H.; Feldman, Gene C.; Fields, Erik; Franz, Bryan A.; Kuring, Norman A.; Mengelt, Claudia; Nelson, Norman B.; Patt, Fred S.; Robinson, Wayne D.; Sarmiento, J. L.; Swan, C. M.; Werdell, Paul J.; Westberry, T. K.; Wilding, John G.; Yoder, J. A.

    2013-01-01

    Photosynthetic production of organic matter by microscopic oceanic phytoplankton fuels ocean ecosystems and contributes roughly half of the Earth's net primary production. For 13 years, the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) mission provided the first consistent, synoptic observations of global ocean ecosystems. Changes in the surface chlorophyll concentration, the primary biological property retrieved from SeaWiFS, have traditionally been used as a metric for phytoplankton abundance and its distribution largely reflects patterns in vertical nutrient transport. On regional to global scales, chlorophyll concentrations covary with sea surface temperature (SST) because SST changes reflect light and nutrient conditions. However, the oceanmay be too complex to be well characterized using a single index such as the chlorophyll concentration. A semi-analytical bio-optical algorithm is used to help interpret regional to global SeaWiFS chlorophyll observations from using three independent, well-validated ocean color data products; the chlorophyll a concentration, absorption by CDM and particulate backscattering. First, we show that observed long-term, global-scale trends in standard chlorophyll retrievals are likely compromised by coincident changes in CDM. Second, we partition the chlorophyll signal into a component due to phytoplankton biomass changes and a component caused by physiological adjustments in intracellular chlorophyll concentrations to changes in mixed layer light levels. We show that biomass changes dominate chlorophyll signals for the high latitude seas and where persistent vertical upwelling is known to occur, while physiological processes dominate chlorophyll variability over much of the tropical and subtropical oceans. The SeaWiFS data set demonstrates complexity in the interpretation of changes in regional to global phytoplankton distributions and illustrates limitations for the assessment of phytoplankton dynamics using chlorophyll

  10. Accurate Anisotropic Fast Marching for Diffusion-Based Geodesic Tractography

    PubMed Central

    Jbabdi, S.; Bellec, P.; Toro, R.; Daunizeau, J.; Pélégrini-Issac, M.; Benali, H.

    2008-01-01

    Using geodesics for inferring white matter fibre tracts from diffusion-weighted MR data is an attractive method for at least two reasons: (i) the method optimises a global criterion, and hence is less sensitive to local perturbations such as noise or partial volume effects, and (ii) the method is fast, allowing to infer on a large number of connexions in a reasonable computational time. Here, we propose an improved fast marching algorithm to infer on geodesic paths. Specifically, this procedure is designed to achieve accurate front propagation in an anisotropic elliptic medium, such as DTI data. We evaluate the numerical performance of this approach on simulated datasets, as well as its robustness to local perturbation induced by fiber crossing. On real data, we demonstrate the feasibility of extracting geodesics to connect an extended set of brain regions. PMID:18299703

  11. New model accurately predicts reformate composition

    SciTech Connect

    Ancheyta-Juarez, J.; Aguilar-Rodriguez, E. )

    1994-01-31

    Although naphtha reforming is a well-known process, the evolution of catalyst formulation, as well as new trends in gasoline specifications, have led to rapid evolution of the process, including: reactor design, regeneration mode, and operating conditions. Mathematical modeling of the reforming process is an increasingly important tool. It is fundamental to the proper design of new reactors and revamp of existing ones. Modeling can be used to optimize operating conditions, analyze the effects of process variables, and enhance unit performance. Instituto Mexicano del Petroleo has developed a model of the catalytic reforming process that accurately predicts reformate composition at the higher-severity conditions at which new reformers are being designed. The new AA model is more accurate than previous proposals because it takes into account the effects of temperature and pressure on the rate constants of each chemical reaction.

  12. Accurate colorimetric feedback for RGB LED clusters

    NASA Astrophysics Data System (ADS)

    Man, Kwong; Ashdown, Ian

    2006-08-01

    We present an empirical model of LED emission spectra that is applicable to both InGaN and AlInGaP high-flux LEDs, and which accurately predicts their relative spectral power distributions over a wide range of LED junction temperatures. We further demonstrate with laboratory measurements that changes in LED spectral power distribution with temperature can be accurately predicted with first- or second-order equations. This provides the basis for a real-time colorimetric feedback system for RGB LED clusters that can maintain the chromaticity of white light at constant intensity to within +/-0.003 Δuv over a range of 45 degrees Celsius, and to within 0.01 Δuv when dimmed over an intensity range of 10:1.

  13. Accurate mask model for advanced nodes

    NASA Astrophysics Data System (ADS)

    Zine El Abidine, Nacer; Sundermann, Frank; Yesilada, Emek; Ndiaye, El Hadji Omar; Mishra, Kushlendra; Paninjath, Sankaranarayanan; Bork, Ingo; Buck, Peter; Toublan, Olivier; Schanen, Isabelle

    2014-07-01

    Standard OPC models consist of a physical optical model and an empirical resist model. The resist model compensates the optical model imprecision on top of modeling resist development. The optical model imprecision may result from mask topography effects and real mask information including mask ebeam writing and mask process contributions. For advanced technology nodes, significant progress has been made to model mask topography to improve optical model accuracy. However, mask information is difficult to decorrelate from standard OPC model. Our goal is to establish an accurate mask model through a dedicated calibration exercise. In this paper, we present a flow to calibrate an accurate mask enabling its implementation. The study covers the different effects that should be embedded in the mask model as well as the experiment required to model them.

  14. Accurate guitar tuning by cochlear implant musicians.

    PubMed

    Lu, Thomas; Huang, Juan; Zeng, Fan-Gang

    2014-01-01

    Modern cochlear implant (CI) users understand speech but find difficulty in music appreciation due to poor pitch perception. Still, some deaf musicians continue to perform with their CI. Here we show unexpected results that CI musicians can reliably tune a guitar by CI alone and, under controlled conditions, match simultaneously presented tones to <0.5 Hz. One subject had normal contralateral hearing and produced more accurate tuning with CI than his normal ear. To understand these counterintuitive findings, we presented tones sequentially and found that tuning error was larger at ∼ 30 Hz for both subjects. A third subject, a non-musician CI user with normal contralateral hearing, showed similar trends in performance between CI and normal hearing ears but with less precision. This difference, along with electric analysis, showed that accurate tuning was achieved by listening to beats rather than discriminating pitch, effectively turning a spectral task into a temporal discrimination task. PMID:24651081

  15. Two highly accurate methods for pitch calibration

    NASA Astrophysics Data System (ADS)

    Kniel, K.; Härtig, F.; Osawa, S.; Sato, O.

    2009-11-01

    Among profiles, helix and tooth thickness pitch is one of the most important parameters of an involute gear measurement evaluation. In principle, coordinate measuring machines (CMM) and CNC-controlled gear measuring machines as a variant of a CMM are suited for these kinds of gear measurements. Now the Japan National Institute of Advanced Industrial Science and Technology (NMIJ/AIST) and the German national metrology institute the Physikalisch-Technische Bundesanstalt (PTB) have each developed independently highly accurate pitch calibration methods applicable to CMM or gear measuring machines. Both calibration methods are based on the so-called closure technique which allows the separation of the systematic errors of the measurement device and the errors of the gear. For the verification of both calibration methods, NMIJ/AIST and PTB performed measurements on a specially designed pitch artifact. The comparison of the results shows that both methods can be used for highly accurate calibrations of pitch standards.

  16. Accurate modeling of parallel scientific computations

    NASA Technical Reports Server (NTRS)

    Nicol, David M.; Townsend, James C.

    1988-01-01

    Scientific codes are usually parallelized by partitioning a grid among processors. To achieve top performance it is necessary to partition the grid so as to balance workload and minimize communication/synchronization costs. This problem is particularly acute when the grid is irregular, changes over the course of the computation, and is not known until load time. Critical mapping and remapping decisions rest on the ability to accurately predict performance, given a description of a grid and its partition. This paper discusses one approach to this problem, and illustrates its use on a one-dimensional fluids code. The models constructed are shown to be accurate, and are used to find optimal remapping schedules.

  17. Accurate Guitar Tuning by Cochlear Implant Musicians

    PubMed Central

    Lu, Thomas; Huang, Juan; Zeng, Fan-Gang

    2014-01-01

    Modern cochlear implant (CI) users understand speech but find difficulty in music appreciation due to poor pitch perception. Still, some deaf musicians continue to perform with their CI. Here we show unexpected results that CI musicians can reliably tune a guitar by CI alone and, under controlled conditions, match simultaneously presented tones to <0.5 Hz. One subject had normal contralateral hearing and produced more accurate tuning with CI than his normal ear. To understand these counterintuitive findings, we presented tones sequentially and found that tuning error was larger at ∼30 Hz for both subjects. A third subject, a non-musician CI user with normal contralateral hearing, showed similar trends in performance between CI and normal hearing ears but with less precision. This difference, along with electric analysis, showed that accurate tuning was achieved by listening to beats rather than discriminating pitch, effectively turning a spectral task into a temporal discrimination task. PMID:24651081

  18. An accurate registration technique for distorted images

    NASA Technical Reports Server (NTRS)

    Delapena, Michele; Shaw, Richard A.; Linde, Peter; Dravins, Dainis

    1990-01-01

    Accurate registration of International Ultraviolet Explorer (IUE) images is crucial because the variability of the geometrical distortions that are introduced by the SEC-Vidicon cameras ensures that raw science images are never perfectly aligned with the Intensity Transfer Functions (ITFs) (i.e., graded floodlamp exposures that are used to linearize and normalize the camera response). A technique for precisely registering IUE images which uses a cross correlation of the fixed pattern that exists in all raw IUE images is described.

  19. Accurate maser positions for MALT-45

    NASA Astrophysics Data System (ADS)

    Jordan, Christopher; Bains, Indra; Voronkov, Maxim; Lo, Nadia; Jones, Paul; Muller, Erik; Cunningham, Maria; Burton, Michael; Brooks, Kate; Green, James; Fuller, Gary; Barnes, Peter; Ellingsen, Simon; Urquhart, James; Morgan, Larry; Rowell, Gavin; Walsh, Andrew; Loenen, Edo; Baan, Willem; Hill, Tracey; Purcell, Cormac; Breen, Shari; Peretto, Nicolas; Jackson, James; Lowe, Vicki; Longmore, Steven

    2013-10-01

    MALT-45 is an untargeted survey, mapping the Galactic plane in CS (1-0), Class I methanol masers, SiO masers and thermal emission, and high frequency continuum emission. After obtaining images from the survey, a number of masers were detected, but without accurate positions. This project seeks to resolve each maser and its environment, with the ultimate goal of placing the Class I methanol maser into a timeline of high mass star formation.

  20. Quasars as very-accurate clock synchronizers

    NASA Technical Reports Server (NTRS)

    Hurd, W. J.; Goldstein, R. M.

    1975-01-01

    Quasars can be employed to synchronize global data communications, geophysical measurements, and atomic clocks. It is potentially two to three orders of magnitude better than presently-used Moon-bounce system. Comparisons between quasar and clock pulses are used to develop correction or synchronization factors for station clocks.

  1. Accurate phase-shift velocimetry in rock.

    PubMed

    Shukla, Matsyendra Nath; Vallatos, Antoine; Phoenix, Vernon R; Holmes, William M

    2016-06-01

    Spatially resolved Pulsed Field Gradient (PFG) velocimetry techniques can provide precious information concerning flow through opaque systems, including rocks. This velocimetry data is used to enhance flow models in a wide range of systems, from oil behaviour in reservoir rocks to contaminant transport in aquifers. Phase-shift velocimetry is the fastest way to produce velocity maps but critical issues have been reported when studying flow through rocks and porous media, leading to inaccurate results. Combining PFG measurements for flow through Bentheimer sandstone with simulations, we demonstrate that asymmetries in the molecular displacement distributions within each voxel are the main source of phase-shift velocimetry errors. We show that when flow-related average molecular displacements are negligible compared to self-diffusion ones, symmetric displacement distributions can be obtained while phase measurement noise is minimised. We elaborate a complete method for the production of accurate phase-shift velocimetry maps in rocks and low porosity media and demonstrate its validity for a range of flow rates. This development of accurate phase-shift velocimetry now enables more rapid and accurate velocity analysis, potentially helping to inform both industrial applications and theoretical models. PMID:27111139

  2. Accurate Molecular Polarizabilities Based on Continuum Electrostatics

    PubMed Central

    Truchon, Jean-François; Nicholls, Anthony; Iftimie, Radu I.; Roux, Benoît; Bayly, Christopher I.

    2013-01-01

    A novel approach for representing the intramolecular polarizability as a continuum dielectric is introduced to account for molecular electronic polarization. It is shown, using a finite-difference solution to the Poisson equation, that the Electronic Polarization from Internal Continuum (EPIC) model yields accurate gas-phase molecular polarizability tensors for a test set of 98 challenging molecules composed of heteroaromatics, alkanes and diatomics. The electronic polarization originates from a high intramolecular dielectric that produces polarizabilities consistent with B3LYP/aug-cc-pVTZ and experimental values when surrounded by vacuum dielectric. In contrast to other approaches to model electronic polarization, this simple model avoids the polarizability catastrophe and accurately calculates molecular anisotropy with the use of very few fitted parameters and without resorting to auxiliary sites or anisotropic atomic centers. On average, the unsigned error in the average polarizability and anisotropy compared to B3LYP are 2% and 5%, respectively. The correlation between the polarizability components from B3LYP and this approach lead to a R2 of 0.990 and a slope of 0.999. Even the F2 anisotropy, shown to be a difficult case for existing polarizability models, can be reproduced within 2% error. In addition to providing new parameters for a rapid method directly applicable to the calculation of polarizabilities, this work extends the widely used Poisson equation to areas where accurate molecular polarizabilities matter. PMID:23646034

  3. Accurate phase-shift velocimetry in rock

    NASA Astrophysics Data System (ADS)

    Shukla, Matsyendra Nath; Vallatos, Antoine; Phoenix, Vernon R.; Holmes, William M.

    2016-06-01

    Spatially resolved Pulsed Field Gradient (PFG) velocimetry techniques can provide precious information concerning flow through opaque systems, including rocks. This velocimetry data is used to enhance flow models in a wide range of systems, from oil behaviour in reservoir rocks to contaminant transport in aquifers. Phase-shift velocimetry is the fastest way to produce velocity maps but critical issues have been reported when studying flow through rocks and porous media, leading to inaccurate results. Combining PFG measurements for flow through Bentheimer sandstone with simulations, we demonstrate that asymmetries in the molecular displacement distributions within each voxel are the main source of phase-shift velocimetry errors. We show that when flow-related average molecular displacements are negligible compared to self-diffusion ones, symmetric displacement distributions can be obtained while phase measurement noise is minimised. We elaborate a complete method for the production of accurate phase-shift velocimetry maps in rocks and low porosity media and demonstrate its validity for a range of flow rates. This development of accurate phase-shift velocimetry now enables more rapid and accurate velocity analysis, potentially helping to inform both industrial applications and theoretical models.

  4. High Frequency QRS ECG Accurately Detects Cardiomyopathy

    NASA Technical Reports Server (NTRS)

    Schlegel, Todd T.; Arenare, Brian; Poulin, Gregory; Moser, Daniel R.; Delgado, Reynolds

    2005-01-01

    High frequency (HF, 150-250 Hz) analysis over the entire QRS interval of the ECG is more sensitive than conventional ECG for detecting myocardial ischemia. However, the accuracy of HF QRS ECG for detecting cardiomyopathy is unknown. We obtained simultaneous resting conventional and HF QRS 12-lead ECGs in 66 patients with cardiomyopathy (EF = 23.2 plus or minus 6.l%, mean plus or minus SD) and in 66 age- and gender-matched healthy controls using PC-based ECG software recently developed at NASA. The single most accurate ECG parameter for detecting cardiomyopathy was an HF QRS morphological score that takes into consideration the total number and severity of reduced amplitude zones (RAZs) present plus the clustering of RAZs together in contiguous leads. This RAZ score had an area under the receiver operator curve (ROC) of 0.91, and was 88% sensitive, 82% specific and 85% accurate for identifying cardiomyopathy at optimum score cut-off of 140 points. Although conventional ECG parameters such as the QRS and QTc intervals were also significantly longer in patients than controls (P less than 0.001, BBBs excluded), these conventional parameters were less accurate (area under the ROC = 0.77 and 0.77, respectively) than HF QRS morphological parameters for identifying underlying cardiomyopathy. The total amplitude of the HF QRS complexes, as measured by summed root mean square voltages (RMSVs), also differed between patients and controls (33.8 plus or minus 11.5 vs. 41.5 plus or minus 13.6 mV, respectively, P less than 0.003), but this parameter was even less accurate in distinguishing the two groups (area under ROC = 0.67) than the HF QRS morphologic and conventional ECG parameters. Diagnostic accuracy was optimal (86%) when the RAZ score from the HF QRS ECG and the QTc interval from the conventional ECG were used simultaneously with cut-offs of greater than or equal to 40 points and greater than or equal to 445 ms, respectively. In conclusion 12-lead HF QRS ECG employing

  5. Accurate perception of negative emotions predicts functional capacity in schizophrenia.

    PubMed

    Abram, Samantha V; Karpouzian, Tatiana M; Reilly, James L; Derntl, Birgit; Habel, Ute; Smith, Matthew J

    2014-04-30

    Several studies suggest facial affect perception (FAP) deficits in schizophrenia are linked to poorer social functioning. However, whether reduced functioning is associated with inaccurate perception of specific emotional valence or a global FAP impairment remains unclear. The present study examined whether impairment in the perception of specific emotional valences (positive, negative) and neutrality were uniquely associated with social functioning, using a multimodal social functioning battery. A sample of 59 individuals with schizophrenia and 41 controls completed a computerized FAP task, and measures of functional capacity, social competence, and social attainment. Participants also underwent neuropsychological testing and symptom assessment. Regression analyses revealed that only accurately perceiving negative emotions explained significant variance (7.9%) in functional capacity after accounting for neurocognitive function and symptoms. Partial correlations indicated that accurately perceiving anger, in particular, was positively correlated with functional capacity. FAP for positive, negative, or neutral emotions were not related to social competence or social attainment. Our findings were consistent with prior literature suggesting negative emotions are related to functional capacity in schizophrenia. Furthermore, the observed relationship between perceiving anger and performance of everyday living skills is novel and warrants further exploration. PMID:24524947

  6. A spectrally accurate algorithm for electromagnetic scattering in three dimensions

    NASA Astrophysics Data System (ADS)

    Ganesh, M.; Hawkins, S.

    2006-09-01

    In this work we develop, implement and analyze a high-order spectrally accurate algorithm for computation of the echo area, and monostatic and bistatic radar cross-section (RCS) of a three dimensional perfectly conducting obstacle through simulation of the time-harmonic electromagnetic waves scattered by the conductor. Our scheme is based on a modified boundary integral formulation (of the Maxwell equations) that is tolerant to basis functions that are not tangential on the conductor surface. We test our algorithm with extensive computational experiments using a variety of three dimensional perfect conductors described in spherical coordinates, including benchmark radar targets such as the metallic NASA almond and ogive. The monostatic RCS measurements for non-convex conductors require hundreds of incident waves (boundary conditions). We demonstrate that the monostatic RCS of small (to medium) sized conductors can be computed using over one thousand incident waves within a few minutes (to a few hours) of CPU time. We compare our results with those obtained using method of moments based industrial standard three dimensional electromagnetic codes CARLOS, CICERO, FE-IE, FERM, and FISC. Finally, we prove the spectrally accurate convergence of our algorithm for computing the surface current, far-field, and RCS values of a class of conductors described globally in spherical coordinates.

  7. Subvoxel accurate graph search using non-Euclidean graph space.

    PubMed

    Abràmoff, Michael D; Wu, Xiaodong; Lee, Kyungmoo; Tang, Li

    2014-01-01

    Graph search is attractive for the quantitative analysis of volumetric medical images, and especially for layered tissues, because it allows globally optimal solutions in low-order polynomial time. However, because nodes of graphs typically encode evenly distributed voxels of the volume with arcs connecting orthogonally sampled voxels in Euclidean space, segmentation cannot achieve greater precision than a single unit, i.e. the distance between two adjoining nodes, and partial volume effects are ignored. We generalize the graph to non-Euclidean space by allowing non-equidistant spacing between nodes, so that subvoxel accurate segmentation is achievable. Because the number of nodes and edges in the graph remains the same, running time and memory use are similar, while all the advantages of graph search, including global optimality and computational efficiency, are retained. A deformation field calculated from the volume data adaptively changes regional node density so that node density varies with the inverse of the expected cost. We validated our approach using optical coherence tomography (OCT) images of the retina and 3-D MR of the arterial wall, and achieved statistically significant increased accuracy. Our approach allows improved accuracy in volume data acquired with the same hardware, and also, preserved accuracy with lower resolution, more cost-effective, image acquisition equipment. The method is not limited to any specific imaging modality and readily extensible to higher dimensions. PMID:25314272

  8. Accurately Mapping M31's Microlensing Population

    NASA Astrophysics Data System (ADS)

    Crotts, Arlin

    2004-07-01

    We propose to augment an existing microlensing survey of M31 with source identifications provided by a modest amount of ACS {and WFPC2 parallel} observations to yield an accurate measurement of the masses responsible for microlensing in M31, and presumably much of its dark matter. The main benefit of these data is the determination of the physical {or "einstein"} timescale of each microlensing event, rather than an effective {"FWHM"} timescale, allowing masses to be determined more than twice as accurately as without HST data. The einstein timescale is the ratio of the lensing cross-sectional radius and relative velocities. Velocities are known from kinematics, and the cross-section is directly proportional to the {unknown} lensing mass. We cannot easily measure these quantities without knowing the amplification, hence the baseline magnitude, which requires the resolution of HST to find the source star. This makes a crucial difference because M31 lens m ass determinations can be more accurate than those towards the Magellanic Clouds through our Galaxy's halo {for the same number of microlensing events} due to the better constrained geometry in the M31 microlensing situation. Furthermore, our larger survey, just completed, should yield at least 100 M31 microlensing events, more than any Magellanic survey. A small amount of ACS+WFPC2 imaging will deliver the potential of this large database {about 350 nights}. For the whole survey {and a delta-function mass distribution} the mass error should approach only about 15%, or about 6% error in slope for a power-law distribution. These results will better allow us to pinpoint the lens halo fraction, and the shape of the halo lens spatial distribution, and allow generalization/comparison of the nature of halo dark matter in spiral galaxies. In addition, we will be able to establish the baseline magnitude for about 50, 000 variable stars, as well as measure an unprecedentedly deta iled color-magnitude diagram and luminosity

  9. Accurate measurement of unsteady state fluid temperature

    NASA Astrophysics Data System (ADS)

    Jaremkiewicz, Magdalena

    2016-07-01

    In this paper, two accurate methods for determining the transient fluid temperature were presented. Measurements were conducted for boiling water since its temperature is known. At the beginning the thermometers are at the ambient temperature and next they are immediately immersed into saturated water. The measurements were carried out with two thermometers of different construction but with the same housing outer diameter equal to 15 mm. One of them is a K-type industrial thermometer widely available commercially. The temperature indicated by the thermometer was corrected considering the thermometers as the first or second order inertia devices. The new design of a thermometer was proposed and also used to measure the temperature of boiling water. Its characteristic feature is a cylinder-shaped housing with the sheath thermocouple located in its center. The temperature of the fluid was determined based on measurements taken in the axis of the solid cylindrical element (housing) using the inverse space marching method. Measurements of the transient temperature of the air flowing through the wind tunnel using the same thermometers were also carried out. The proposed measurement technique provides more accurate results compared with measurements using industrial thermometers in conjunction with simple temperature correction using the inertial thermometer model of the first or second order. By comparing the results, it was demonstrated that the new thermometer allows obtaining the fluid temperature much faster and with higher accuracy in comparison to the industrial thermometer. Accurate measurements of the fast changing fluid temperature are possible due to the low inertia thermometer and fast space marching method applied for solving the inverse heat conduction problem.

  10. Accurate upwind methods for the Euler equations

    NASA Technical Reports Server (NTRS)

    Huynh, Hung T.

    1993-01-01

    A new class of piecewise linear methods for the numerical solution of the one-dimensional Euler equations of gas dynamics is presented. These methods are uniformly second-order accurate, and can be considered as extensions of Godunov's scheme. With an appropriate definition of monotonicity preservation for the case of linear convection, it can be shown that they preserve monotonicity. Similar to Van Leer's MUSCL scheme, they consist of two key steps: a reconstruction step followed by an upwind step. For the reconstruction step, a monotonicity constraint that preserves uniform second-order accuracy is introduced. Computational efficiency is enhanced by devising a criterion that detects the 'smooth' part of the data where the constraint is redundant. The concept and coding of the constraint are simplified by the use of the median function. A slope steepening technique, which has no effect at smooth regions and can resolve a contact discontinuity in four cells, is described. As for the upwind step, existing and new methods are applied in a manner slightly different from those in the literature. These methods are derived by approximating the Euler equations via linearization and diagonalization. At a 'smooth' interface, Harten, Lax, and Van Leer's one intermediate state model is employed. A modification for this model that can resolve contact discontinuities is presented. Near a discontinuity, either this modified model or a more accurate one, namely, Roe's flux-difference splitting. is used. The current presentation of Roe's method, via the conceptually simple flux-vector splitting, not only establishes a connection between the two splittings, but also leads to an admissibility correction with no conditional statement, and an efficient approximation to Osher's approximate Riemann solver. These reconstruction and upwind steps result in schemes that are uniformly second-order accurate and economical at smooth regions, and yield high resolution at discontinuities.

  11. The first accurate description of an aurora

    NASA Astrophysics Data System (ADS)

    Schröder, Wilfried

    2006-12-01

    As technology has advanced, the scientific study of auroral phenomena has increased by leaps and bounds. A look back at the earliest descriptions of aurorae offers an interesting look into how medieval scholars viewed the subjects that we study.Although there are earlier fragmentary references in the literature, the first accurate description of the aurora borealis appears to be that published by the German Catholic scholar Konrad von Megenberg (1309-1374) in his book Das Buch der Natur (The Book of Nature). The book was written between 1349 and 1350.

  12. Are Kohn-Sham conductances accurate?

    PubMed

    Mera, H; Niquet, Y M

    2010-11-19

    We use Fermi-liquid relations to address the accuracy of conductances calculated from the single-particle states of exact Kohn-Sham (KS) density functional theory. We demonstrate a systematic failure of this procedure for the calculation of the conductance, and show how it originates from the lack of renormalization in the KS spectral function. In certain limits this failure can lead to a large overestimation of the true conductance. We also show, however, that the KS conductances can be accurate for single-channel molecular junctions and systems where direct Coulomb interactions are strongly dominant. PMID:21231333

  13. Accurate density functional thermochemistry for larger molecules.

    SciTech Connect

    Raghavachari, K.; Stefanov, B. B.; Curtiss, L. A.; Lucent Tech.

    1997-06-20

    Density functional methods are combined with isodesmic bond separation reaction energies to yield accurate thermochemistry for larger molecules. Seven different density functionals are assessed for the evaluation of heats of formation, Delta H 0 (298 K), for a test set of 40 molecules composed of H, C, O and N. The use of bond separation energies results in a dramatic improvement in the accuracy of all the density functionals. The B3-LYP functional has the smallest mean absolute deviation from experiment (1.5 kcal mol/f).

  14. New law requires 'medically accurate' lesson plans.

    PubMed

    1999-09-17

    The California Legislature has passed a bill requiring all textbooks and materials used to teach about AIDS be medically accurate and objective. Statements made within the curriculum must be supported by research conducted in compliance with scientific methods, and published in peer-reviewed journals. Some of the current lesson plans were found to contain scientifically unsupported and biased information. In addition, the bill requires material to be "free of racial, ethnic, or gender biases." The legislation is supported by a wide range of interests, but opposed by the California Right to Life Education Fund, because they believe it discredits abstinence-only material. PMID:11366835

  15. Remote-sensing-based measurement of phytoplankton size spectrum and cell diameter in the global oceans

    NASA Astrophysics Data System (ADS)

    Roy, S.; Sathyendranath, S.; Bouman, H. A.; Platt, T.

    2012-12-01

    Oceanic phytoplankton regulate the spectral quality of the submarine light field because light absorption by phytoplankton is spectrally structured, with a maximum in the blue and a secondary maximum in the red. The spectral characteristics of absorption are variable with phytoplankton taxa, and also with cell size and growth conditions. The intra-cellular concentration of light-absorbing pigments varies with phytoplankton size, which in turn modulates its specific absorption. The changes in phytoplankton cell size alter not only the bio-optical properties of the water column, but also the trophic interactions within the ecosystem. It is thus important to study the time evolution of phytoplankton size structure over the global ocean. We have developed a novel model that uses the light absorption coefficient of phytoplankton to retrieve quantitative information about phytoplankton size structure from satellite-derived ocean-colour data. The application of the method to satellite remote sensing at any given spatial location depends on the estimates of the concentration of chlorophyll-a, which is an operational index of phytoplankton biomass, and the remote sensing reflectance at different wavelengths in the visible domain. Using our method we have computed the equivalent spherical diameter of phytoplankton cells and the exponent of particle-size spectrum of phytoplankton, and thereby estimated the chlorophyll distribution in different phytoplankton size classes on a global scale. The spatial distribution of the size-spectrum exponent and the biomass fractions of pico-, nano- and micro-phytoplankton estimated are consistent with our current understanding of phytoplankton functional types in the global oceans. The study will enhance our understanding of the distribution and time evolution of phytoplankton size structure in the global oceans.

  16. Accurate basis set truncation for wavefunction embedding

    NASA Astrophysics Data System (ADS)

    Barnes, Taylor A.; Goodpaster, Jason D.; Manby, Frederick R.; Miller, Thomas F.

    2013-07-01

    Density functional theory (DFT) provides a formally exact framework for performing embedded subsystem electronic structure calculations, including DFT-in-DFT and wavefunction theory-in-DFT descriptions. In the interest of efficiency, it is desirable to truncate the atomic orbital basis set in which the subsystem calculation is performed, thus avoiding high-order scaling with respect to the size of the MO virtual space. In this study, we extend a recently introduced projection-based embedding method [F. R. Manby, M. Stella, J. D. Goodpaster, and T. F. Miller III, J. Chem. Theory Comput. 8, 2564 (2012)], 10.1021/ct300544e to allow for the systematic and accurate truncation of the embedded subsystem basis set. The approach is applied to both covalently and non-covalently bound test cases, including water clusters and polypeptide chains, and it is demonstrated that errors associated with basis set truncation are controllable to well within chemical accuracy. Furthermore, we show that this approach allows for switching between accurate projection-based embedding and DFT embedding with approximate kinetic energy (KE) functionals; in this sense, the approach provides a means of systematically improving upon the use of approximate KE functionals in DFT embedding.

  17. Accurate radiative transfer calculations for layered media.

    PubMed

    Selden, Adrian C

    2016-07-01

    Simple yet accurate results for radiative transfer in layered media with discontinuous refractive index are obtained by the method of K-integrals. These are certain weighted integrals applied to the angular intensity distribution at the refracting boundaries. The radiative intensity is expressed as the sum of the asymptotic angular intensity distribution valid in the depth of the scattering medium and a transient term valid near the boundary. Integrated boundary equations are obtained, yielding simple linear equations for the intensity coefficients, enabling the angular emission intensity and the diffuse reflectance (albedo) and transmittance of the scattering layer to be calculated without solving the radiative transfer equation directly. Examples are given of half-space, slab, interface, and double-layer calculations, and extensions to multilayer systems are indicated. The K-integral method is orders of magnitude more accurate than diffusion theory and can be applied to layered scattering media with a wide range of scattering albedos, with potential applications to biomedical and ocean optics. PMID:27409700

  18. Fast and accurate propagation of coherent light

    PubMed Central

    Lewis, R. D.; Beylkin, G.; Monzón, L.

    2013-01-01

    We describe a fast algorithm to propagate, for any user-specified accuracy, a time-harmonic electromagnetic field between two parallel planes separated by a linear, isotropic and homogeneous medium. The analytical formulation of this problem (ca 1897) requires the evaluation of the so-called Rayleigh–Sommerfeld integral. If the distance between the planes is small, this integral can be accurately evaluated in the Fourier domain; if the distance is very large, it can be accurately approximated by asymptotic methods. In the large intermediate region of practical interest, where the oscillatory Rayleigh–Sommerfeld kernel must be applied directly, current numerical methods can be highly inaccurate without indicating this fact to the user. In our approach, for any user-specified accuracy ϵ>0, we approximate the kernel by a short sum of Gaussians with complex-valued exponents, and then efficiently apply the result to the input data using the unequally spaced fast Fourier transform. The resulting algorithm has computational complexity , where we evaluate the solution on an N×N grid of output points given an M×M grid of input samples. Our algorithm maintains its accuracy throughout the computational domain. PMID:24204184

  19. How Accurately can we Calculate Thermal Systems?

    SciTech Connect

    Cullen, D; Blomquist, R N; Dean, C; Heinrichs, D; Kalugin, M A; Lee, M; Lee, Y; MacFarlan, R; Nagaya, Y; Trkov, A

    2004-04-20

    I would like to determine how accurately a variety of neutron transport code packages (code and cross section libraries) can calculate simple integral parameters, such as K{sub eff}, for systems that are sensitive to thermal neutron scattering. Since we will only consider theoretical systems, we cannot really determine absolute accuracy compared to any real system. Therefore rather than accuracy, it would be more precise to say that I would like to determine the spread in answers that we obtain from a variety of code packages. This spread should serve as an excellent indicator of how accurately we can really model and calculate such systems today. Hopefully, eventually this will lead to improvements in both our codes and the thermal scattering models that they use in the future. In order to accomplish this I propose a number of extremely simple systems that involve thermal neutron scattering that can be easily modeled and calculated by a variety of neutron transport codes. These are theoretical systems designed to emphasize the effects of thermal scattering, since that is what we are interested in studying. I have attempted to keep these systems very simple, and yet at the same time they include most, if not all, of the important thermal scattering effects encountered in a large, water-moderated, uranium fueled thermal system, i.e., our typical thermal reactors.

  20. Accurate shear measurement with faint sources

    SciTech Connect

    Zhang, Jun; Foucaud, Sebastien; Luo, Wentao E-mail: walt@shao.ac.cn

    2015-01-01

    For cosmic shear to become an accurate cosmological probe, systematic errors in the shear measurement method must be unambiguously identified and corrected for. Previous work of this series has demonstrated that cosmic shears can be measured accurately in Fourier space in the presence of background noise and finite pixel size, without assumptions on the morphologies of galaxy and PSF. The remaining major source of error is source Poisson noise, due to the finiteness of source photon number. This problem is particularly important for faint galaxies in space-based weak lensing measurements, and for ground-based images of short exposure times. In this work, we propose a simple and rigorous way of removing the shear bias from the source Poisson noise. Our noise treatment can be generalized for images made of multiple exposures through MultiDrizzle. This is demonstrated with the SDSS and COSMOS/ACS data. With a large ensemble of mock galaxy images of unrestricted morphologies, we show that our shear measurement method can achieve sub-percent level accuracy even for images of signal-to-noise ratio less than 5 in general, making it the most promising technique for cosmic shear measurement in the ongoing and upcoming large scale galaxy surveys.

  1. Accurate pose estimation for forensic identification

    NASA Astrophysics Data System (ADS)

    Merckx, Gert; Hermans, Jeroen; Vandermeulen, Dirk

    2010-04-01

    In forensic authentication, one aims to identify the perpetrator among a series of suspects or distractors. A fundamental problem in any recognition system that aims for identification of subjects in a natural scene is the lack of constrains on viewing and imaging conditions. In forensic applications, identification proves even more challenging, since most surveillance footage is of abysmal quality. In this context, robust methods for pose estimation are paramount. In this paper we will therefore present a new pose estimation strategy for very low quality footage. Our approach uses 3D-2D registration of a textured 3D face model with the surveillance image to obtain accurate far field pose alignment. Starting from an inaccurate initial estimate, the technique uses novel similarity measures based on the monogenic signal to guide a pose optimization process. We will illustrate the descriptive strength of the introduced similarity measures by using them directly as a recognition metric. Through validation, using both real and synthetic surveillance footage, our pose estimation method is shown to be accurate, and robust to lighting changes and image degradation.

  2. Accurate determination of characteristic relative permeability curves

    NASA Astrophysics Data System (ADS)

    Krause, Michael H.; Benson, Sally M.

    2015-09-01

    A recently developed technique to accurately characterize sub-core scale heterogeneity is applied to investigate the factors responsible for flowrate-dependent effective relative permeability curves measured on core samples in the laboratory. The dependency of laboratory measured relative permeability on flowrate has long been both supported and challenged by a number of investigators. Studies have shown that this apparent flowrate dependency is a result of both sub-core scale heterogeneity and outlet boundary effects. However this has only been demonstrated numerically for highly simplified models of porous media. In this paper, flowrate dependency of effective relative permeability is demonstrated using two rock cores, a Berea Sandstone and a heterogeneous sandstone from the Otway Basin Pilot Project in Australia. Numerical simulations of steady-state coreflooding experiments are conducted at a number of injection rates using a single set of input characteristic relative permeability curves. Effective relative permeability is then calculated from the simulation data using standard interpretation methods for calculating relative permeability from steady-state tests. Results show that simplified approaches may be used to determine flowrate-independent characteristic relative permeability provided flow rate is sufficiently high, and the core heterogeneity is relatively low. It is also shown that characteristic relative permeability can be determined at any typical flowrate, and even for geologically complex models, when using accurate three-dimensional models.

  3. Global Composite

    Atmospheric Science Data Center

    2013-04-19

    article title:  MISR Global Images See the Light of Day     View Larger Image ... than its nadir counterpart due to enhanced reflection of light by atmospheric particulates. MISR data are processed at the ...

  4. Are National HFC Inventory Reports Accurate?

    NASA Astrophysics Data System (ADS)

    Lunt, M. F.; Rigby, M. L.; Ganesan, A.; Manning, A.; O'Doherty, S.; Prinn, R. G.; Saito, T.; Harth, C. M.; Muhle, J.; Weiss, R. F.; Salameh, P.; Arnold, T.; Yokouchi, Y.; Krummel, P. B.; Steele, P.; Fraser, P. J.; Li, S.; Park, S.; Kim, J.; Reimann, S.; Vollmer, M. K.; Lunder, C. R.; Hermansen, O.; Schmidbauer, N.; Young, D.; Simmonds, P. G.

    2014-12-01

    Hydrofluorocarbons (HFCs) were introduced as replacements for ozone depleting chlorinated gases due to their negligible ozone depletion potential. As a result, these potent greenhouse gases are now rapidly increasing in atmospheric mole fraction. However, at present, less than 50% of HFC emissions, as inferred from models combined with atmospheric measurements (top-down methods), can be accounted for by the annual national reports to the United Nations Framework Convention on Climate Change (UNFCCC). There are at least two possible reasons for the discrepancy. Firstly, significant emissions could be originating from countries not required to report to the UNFCCC ("non-Annex 1" countries). Secondly, emissions reports themselves may be subject to inaccuracies. For example the HFC emission factors used in the 'bottom-up' calculation of emissions tend to be technology-specific (refrigeration, air conditioning etc.), but not tuned to the properties of individual HFCs. To provide a new top-down perspective, we inferred emissions using high frequency HFC measurements from the Advanced Global Atmospheric Gases Experiment (AGAGE) and the National Institute for Environmental Studies (NIES) networks. Global and regional emissions information was inferred from these measurements using a coupled Eulerian and Lagrangian system, based on NCAR's MOZART model and the UK Met Office NAME model. Uncertainties in this measurement and modelling framework were investigated using a hierarchical Bayesian inverse method. Global and regional emissions estimates for five of the major HFCs (HFC-134a, HFC-125, HFC-143a, HFC-32, HFC-152a) from 2004-2012 are presented. It was found that, when aggregated, the top-down estimates from Annex 1 countries agreed remarkably well with the reported emissions, suggesting the non-Annex 1 emissions make up the difference with the top-down global estimate. However, when these HFC species are viewed individually we find that emissions of HFC-134a are over

  5. Accurate Thermal Stresses for Beams: Normal Stress

    NASA Technical Reports Server (NTRS)

    Johnson, Theodore F.; Pilkey, Walter D.

    2003-01-01

    Formulations for a general theory of thermoelasticity to generate accurate thermal stresses for structural members of aeronautical vehicles were developed in 1954 by Boley. The formulation also provides three normal stresses and a shear stress along the entire length of the beam. The Poisson effect of the lateral and transverse normal stresses on a thermally loaded beam is taken into account in this theory by employing an Airy stress function. The Airy stress function enables the reduction of the three-dimensional thermal stress problem to a two-dimensional one. Numerical results from the general theory of thermoelasticity are compared to those obtained from strength of materials. It is concluded that the theory of thermoelasticity for prismatic beams proposed in this paper can be used instead of strength of materials when precise stress results are desired.

  6. Accurate Thermal Stresses for Beams: Normal Stress

    NASA Technical Reports Server (NTRS)

    Johnson, Theodore F.; Pilkey, Walter D.

    2002-01-01

    Formulations for a general theory of thermoelasticity to generate accurate thermal stresses for structural members of aeronautical vehicles were developed in 1954 by Boley. The formulation also provides three normal stresses and a shear stress along the entire length of the beam. The Poisson effect of the lateral and transverse normal stresses on a thermally loaded beam is taken into account in this theory by employing an Airy stress function. The Airy stress function enables the reduction of the three-dimensional thermal stress problem to a two-dimensional one. Numerical results from the general theory of thermoelasticity are compared to those obtained from strength of materials. It is concluded that the theory of thermoelasticity for prismatic beams proposed in this paper can be used instead of strength of materials when precise stress results are desired.

  7. Highly accurate articulated coordinate measuring machine

    DOEpatents

    Bieg, Lothar F.; Jokiel, Jr., Bernhard; Ensz, Mark T.; Watson, Robert D.

    2003-12-30

    Disclosed is a highly accurate articulated coordinate measuring machine, comprising a revolute joint, comprising a circular encoder wheel, having an axis of rotation; a plurality of marks disposed around at least a portion of the circumference of the encoder wheel; bearing means for supporting the encoder wheel, while permitting free rotation of the encoder wheel about the wheel's axis of rotation; and a sensor, rigidly attached to the bearing means, for detecting the motion of at least some of the marks as the encoder wheel rotates; a probe arm, having a proximal end rigidly attached to the encoder wheel, and having a distal end with a probe tip attached thereto; and coordinate processing means, operatively connected to the sensor, for converting the output of the sensor into a set of cylindrical coordinates representing the position of the probe tip relative to a reference cylindrical coordinate system.

  8. Practical aspects of spatially high accurate methods

    NASA Technical Reports Server (NTRS)

    Godfrey, Andrew G.; Mitchell, Curtis R.; Walters, Robert W.

    1992-01-01

    The computational qualities of high order spatially accurate methods for the finite volume solution of the Euler equations are presented. Two dimensional essentially non-oscillatory (ENO), k-exact, and 'dimension by dimension' ENO reconstruction operators are discussed and compared in terms of reconstruction and solution accuracy, computational cost and oscillatory behavior in supersonic flows with shocks. Inherent steady state convergence difficulties are demonstrated for adaptive stencil algorithms. An exact solution to the heat equation is used to determine reconstruction error, and the computational intensity is reflected in operation counts. Standard MUSCL differencing is included for comparison. Numerical experiments presented include the Ringleb flow for numerical accuracy and a shock reflection problem. A vortex-shock interaction demonstrates the ability of the ENO scheme to excel in simulating unsteady high-frequency flow physics.

  9. The thermodynamic cost of accurate sensory adaptation

    NASA Astrophysics Data System (ADS)

    Tu, Yuhai

    2015-03-01

    Living organisms need to obtain and process environment information accurately in order to make decisions critical for their survival. Much progress have been made in identifying key components responsible for various biological functions, however, major challenges remain to understand system-level behaviors from the molecular-level knowledge of biology and to unravel possible physical principles for the underlying biochemical circuits. In this talk, we will present some recent works in understanding the chemical sensory system of E. coli by combining theoretical approaches with quantitative experiments. We focus on addressing the questions on how cells process chemical information and adapt to varying environment, and what are the thermodynamic limits of key regulatory functions, such as adaptation.

  10. Accurate numerical solutions of conservative nonlinear oscillators

    NASA Astrophysics Data System (ADS)

    Khan, Najeeb Alam; Nasir Uddin, Khan; Nadeem Alam, Khan

    2014-12-01

    The objective of this paper is to present an investigation to analyze the vibration of a conservative nonlinear oscillator in the form u" + lambda u + u^(2n-1) + (1 + epsilon^2 u^(4m))^(1/2) = 0 for any arbitrary power of n and m. This method converts the differential equation to sets of algebraic equations and solve numerically. We have presented for three different cases: a higher order Duffing equation, an equation with irrational restoring force and a plasma physics equation. It is also found that the method is valid for any arbitrary order of n and m. Comparisons have been made with the results found in the literature the method gives accurate results.

  11. Accurate Telescope Mount Positioning with MEMS Accelerometers

    NASA Astrophysics Data System (ADS)

    Mészáros, L.; Jaskó, A.; Pál, A.; Csépány, G.

    2014-08-01

    This paper describes the advantages and challenges of applying microelectromechanical accelerometer systems (MEMS accelerometers) in order to attain precise, accurate, and stateless positioning of telescope mounts. This provides a completely independent method from other forms of electronic, optical, mechanical or magnetic feedback or real-time astrometry. Our goal is to reach the subarcminute range which is considerably smaller than the field-of-view of conventional imaging telescope systems. Here we present how this subarcminute accuracy can be achieved with very cheap MEMS sensors and we also detail how our procedures can be extended in order to attain even finer measurements. In addition, our paper discusses how can a complete system design be implemented in order to be a part of a telescope control system.

  12. Accurate metacognition for visual sensory memory representations.

    PubMed

    Vandenbroucke, Annelinde R E; Sligte, Ilja G; Barrett, Adam B; Seth, Anil K; Fahrenfort, Johannes J; Lamme, Victor A F

    2014-04-01

    The capacity to attend to multiple objects in the visual field is limited. However, introspectively, people feel that they see the whole visual world at once. Some scholars suggest that this introspective feeling is based on short-lived sensory memory representations, whereas others argue that the feeling of seeing more than can be attended to is illusory. Here, we investigated this phenomenon by combining objective memory performance with subjective confidence ratings during a change-detection task. This allowed us to compute a measure of metacognition--the degree of knowledge that subjects have about the correctness of their decisions--for different stages of memory. We show that subjects store more objects in sensory memory than they can attend to but, at the same time, have similar metacognition for sensory memory and working memory representations. This suggests that these subjective impressions are not an illusion but accurate reflections of the richness of visual perception. PMID:24549293

  13. Apparatus for accurately measuring high temperatures

    DOEpatents

    Smith, Douglas D.

    1985-01-01

    The present invention is a thermometer used for measuring furnace temperaes in the range of about 1800.degree. to 2700.degree. C. The thermometer comprises a broadband multicolor thermal radiation sensor positioned to be in optical alignment with the end of a blackbody sight tube extending into the furnace. A valve-shutter arrangement is positioned between the radiation sensor and the sight tube and a chamber for containing a charge of high pressure gas is positioned between the valve-shutter arrangement and the radiation sensor. A momentary opening of the valve shutter arrangement allows a pulse of the high gas to purge the sight tube of air-borne thermal radiation contaminants which permits the radiation sensor to accurately measure the thermal radiation emanating from the end of the sight tube.

  14. Apparatus for accurately measuring high temperatures

    DOEpatents

    Smith, D.D.

    The present invention is a thermometer used for measuring furnace temperatures in the range of about 1800/sup 0/ to 2700/sup 0/C. The thermometer comprises a broadband multicolor thermal radiation sensor positioned to be in optical alignment with the end of a blackbody sight tube extending into the furnace. A valve-shutter arrangement is positioned between the radiation sensor and the sight tube and a chamber for containing a charge of high pressure gas is positioned between the valve-shutter arrangement and the radiation sensor. A momentary opening of the valve shutter arrangement allows a pulse of the high gas to purge the sight tube of air-borne thermal radiation contaminants which permits the radiation sensor to accurately measure the thermal radiation emanating from the end of the sight tube.

  15. Toward Accurate and Quantitative Comparative Metagenomics.

    PubMed

    Nayfach, Stephen; Pollard, Katherine S

    2016-08-25

    Shotgun metagenomics and computational analysis are used to compare the taxonomic and functional profiles of microbial communities. Leveraging this approach to understand roles of microbes in human biology and other environments requires quantitative data summaries whose values are comparable across samples and studies. Comparability is currently hampered by the use of abundance statistics that do not estimate a meaningful parameter of the microbial community and biases introduced by experimental protocols and data-cleaning approaches. Addressing these challenges, along with improving study design, data access, metadata standardization, and analysis tools, will enable accurate comparative metagenomics. We envision a future in which microbiome studies are replicable and new metagenomes are easily and rapidly integrated with existing data. Only then can the potential of metagenomics for predictive ecological modeling, well-powered association studies, and effective microbiome medicine be fully realized. PMID:27565341

  16. The importance of accurate atmospheric modeling

    NASA Astrophysics Data System (ADS)

    Payne, Dylan; Schroeder, John; Liang, Pang

    2014-11-01

    This paper will focus on the effect of atmospheric conditions on EO sensor performance using computer models. We have shown the importance of accurately modeling atmospheric effects for predicting the performance of an EO sensor. A simple example will demonstrated how real conditions for several sites in China will significantly impact on image correction, hyperspectral imaging, and remote sensing. The current state-of-the-art model for computing atmospheric transmission and radiance is, MODTRAN® 5, developed by the US Air Force Research Laboratory and Spectral Science, Inc. Research by the US Air Force, Navy and Army resulted in the public release of LOWTRAN 2 in the early 1970's. Subsequent releases of LOWTRAN and MODTRAN® have continued until the present. Please verify that (1) all pages are present, (2) all figures are correct, (3) all fonts and special characters are correct, and (4) all text and figures fit within the red margin lines shown on this review document. Complete formatting information is available at http://SPIE.org/manuscripts Return to the Manage Active Submissions page at http://spie.org/submissions/tasks.aspx and approve or disapprove this submission. Your manuscript will not be published without this approval. Please contact author_help@spie.org with any questions or concerns. The paper will demonstrate the importance of using validated models and local measured meteorological, atmospheric and aerosol conditions to accurately simulate the atmospheric transmission and radiance. Frequently default conditions are used which can produce errors of as much as 75% in these values. This can have significant impact on remote sensing applications.

  17. The high cost of accurate knowledge.

    PubMed

    Sutcliffe, Kathleen M; Weber, Klaus

    2003-05-01

    Many business thinkers believe it's the role of senior managers to scan the external environment to monitor contingencies and constraints, and to use that precise knowledge to modify the company's strategy and design. As these thinkers see it, managers need accurate and abundant information to carry out that role. According to that logic, it makes sense to invest heavily in systems for collecting and organizing competitive information. Another school of pundits contends that, since today's complex information often isn't precise anyway, it's not worth going overboard with such investments. In other words, it's not the accuracy and abundance of information that should matter most to top executives--rather, it's how that information is interpreted. After all, the role of senior managers isn't just to make decisions; it's to set direction and motivate others in the face of ambiguities and conflicting demands. Top executives must interpret information and communicate those interpretations--they must manage meaning more than they must manage information. So which of these competing views is the right one? Research conducted by academics Sutcliffe and Weber found that how accurate senior executives are about their competitive environments is indeed less important for strategy and corresponding organizational changes than the way in which they interpret information about their environments. Investments in shaping those interpretations, therefore, may create a more durable competitive advantage than investments in obtaining and organizing more information. And what kinds of interpretations are most closely linked with high performance? Their research suggests that high performers respond positively to opportunities, yet they aren't overconfident in their abilities to take advantage of those opportunities. PMID:12747164

  18. Accurate Weather Forecasting for Radio Astronomy

    NASA Astrophysics Data System (ADS)

    Maddalena, Ronald J.

    2010-01-01

    The NRAO Green Bank Telescope routinely observes at wavelengths from 3 mm to 1 m. As with all mm-wave telescopes, observing conditions depend upon the variable atmospheric water content. The site provides over 100 days/yr when opacities are low enough for good observing at 3 mm, but winds on the open-air structure reduce the time suitable for 3-mm observing where pointing is critical. Thus, to maximum productivity the observing wavelength needs to match weather conditions. For 6 years the telescope has used a dynamic scheduling system (recently upgraded; www.gb.nrao.edu/DSS) that requires accurate multi-day forecasts for winds and opacities. Since opacity forecasts are not provided by the National Weather Services (NWS), I have developed an automated system that takes available forecasts, derives forecasted opacities, and deploys the results on the web in user-friendly graphical overviews (www.gb.nrao.edu/ rmaddale/Weather). The system relies on the "North American Mesoscale" models, which are updated by the NWS every 6 hrs, have a 12 km horizontal resolution, 1 hr temporal resolution, run to 84 hrs, and have 60 vertical layers that extend to 20 km. Each forecast consists of a time series of ground conditions, cloud coverage, etc, and, most importantly, temperature, pressure, humidity as a function of height. I use the Liebe's MWP model (Radio Science, 20, 1069, 1985) to determine the absorption in each layer for each hour for 30 observing wavelengths. Radiative transfer provides, for each hour and wavelength, the total opacity and the radio brightness of the atmosphere, which contributes substantially at some wavelengths to Tsys and the observational noise. Comparisons of measured and forecasted Tsys at 22.2 and 44 GHz imply that the forecasted opacities are good to about 0.01 Nepers, which is sufficient for forecasting and accurate calibration. Reliability is high out to 2 days and degrades slowly for longer-range forecasts.

  19. A spectrally accurate method for overlapping grid solution of incompressible Navier-Stokes equations

    NASA Astrophysics Data System (ADS)

    Merrill, Brandon E.; Peet, Yulia T.; Fischer, Paul F.; Lottes, James W.

    2016-02-01

    An overlapping mesh methodology that is spectrally accurate in space and up to third-order accurate in time is developed for solution of unsteady incompressible flow equations in three-dimensional domains. The ability to decompose a global domain into separate, but overlapping, subdomains eases mesh generation procedures and increases flexibility of modeling flows with complex geometries. The methodology employs implicit spectral element discretization of equations in each subdomain and explicit treatment of subdomain interfaces with spectrally-accurate spatial interpolation and high-order accurate temporal extrapolation, and requires few, if any, iterations, yet maintains the global accuracy and stability of the underlying flow solver. The overlapping mesh methodology is thoroughly validated using two-dimensional and three-dimensional benchmark problems in laminar and turbulent flows. The spatial and temporal convergence is documented and is in agreement with the nominal order of accuracy of the solver. The influence of long integration times, as well as inflow-outflow global boundary conditions on the performance of the overlapping grid solver is assessed. In a turbulent benchmark of fully-developed turbulent pipe flow, the turbulent statistics with the overlapping grids is validated against published available experimental and other computation data. Scaling tests are presented that show near linear strong scaling, even for moderately large processor counts.

  20. Approaching system equilibrium with accurate or not accurate feedback information in a two-route system

    NASA Astrophysics Data System (ADS)

    Zhao, Xiao-mei; Xie, Dong-fan; Li, Qi

    2015-02-01

    With the development of intelligent transport system, advanced information feedback strategies have been developed to reduce traffic congestion and enhance the capacity. However, previous strategies provide accurate information to travelers and our simulation results show that accurate information brings negative effects, especially in delay case. Because travelers prefer to the best condition route with accurate information, and delayed information cannot reflect current traffic condition but past. Then travelers make wrong routing decisions, causing the decrease of the capacity and the increase of oscillations and the system deviating from the equilibrium. To avoid the negative effect, bounded rationality is taken into account by introducing a boundedly rational threshold BR. When difference between two routes is less than the BR, routes have equal probability to be chosen. The bounded rationality is helpful to improve the efficiency in terms of capacity, oscillation and the gap deviating from the system equilibrium.

  1. Higher order accurate partial implicitization: An unconditionally stable fourth-order-accurate explicit numerical technique

    NASA Technical Reports Server (NTRS)

    Graves, R. A., Jr.

    1975-01-01

    The previously obtained second-order-accurate partial implicitization numerical technique used in the solution of fluid dynamic problems was modified with little complication to achieve fourth-order accuracy. The Von Neumann stability analysis demonstrated the unconditional linear stability of the technique. The order of the truncation error was deduced from the Taylor series expansions of the linearized difference equations and was verified by numerical solutions to Burger's equation. For comparison, results were also obtained for Burger's equation using a second-order-accurate partial-implicitization scheme, as well as the fourth-order scheme of Kreiss.

  2. Accurate Fission Data for Nuclear Safety

    NASA Astrophysics Data System (ADS)

    Solders, A.; Gorelov, D.; Jokinen, A.; Kolhinen, V. S.; Lantz, M.; Mattera, A.; Penttilä, H.; Pomp, S.; Rakopoulos, V.; Rinta-Antila, S.

    2014-05-01

    The Accurate fission data for nuclear safety (AlFONS) project aims at high precision measurements of fission yields, using the renewed IGISOL mass separator facility in combination with a new high current light ion cyclotron at the University of Jyväskylä. The 30 MeV proton beam will be used to create fast and thermal neutron spectra for the study of neutron induced fission yields. Thanks to a series of mass separating elements, culminating with the JYFLTRAP Penning trap, it is possible to achieve a mass resolving power in the order of a few hundred thousands. In this paper we present the experimental setup and the design of a neutron converter target for IGISOL. The goal is to have a flexible design. For studies of exotic nuclei far from stability a high neutron flux (1012 neutrons/s) at energies 1 - 30 MeV is desired while for reactor applications neutron spectra that resembles those of thermal and fast nuclear reactors are preferred. It is also desirable to be able to produce (semi-)monoenergetic neutrons for benchmarking and to study the energy dependence of fission yields. The scientific program is extensive and is planed to start in 2013 with a measurement of isomeric yield ratios of proton induced fission in uranium. This will be followed by studies of independent yields of thermal and fast neutron induced fission of various actinides.

  3. Fast and Provably Accurate Bilateral Filtering

    NASA Astrophysics Data System (ADS)

    Chaudhury, Kunal N.; Dabhade, Swapnil D.

    2016-06-01

    The bilateral filter is a non-linear filter that uses a range filter along with a spatial filter to perform edge-preserving smoothing of images. A direct computation of the bilateral filter requires $O(S)$ operations per pixel, where $S$ is the size of the support of the spatial filter. In this paper, we present a fast and provably accurate algorithm for approximating the bilateral filter when the range kernel is Gaussian. In particular, for box and Gaussian spatial filters, the proposed algorithm can cut down the complexity to $O(1)$ per pixel for any arbitrary $S$. The algorithm has a simple implementation involving $N+1$ spatial filterings, where $N$ is the approximation order. We give a detailed analysis of the filtering accuracy that can be achieved by the proposed approximation in relation to the target bilateral filter. This allows us to to estimate the order $N$ required to obtain a given accuracy. We also present comprehensive numerical results to demonstrate that the proposed algorithm is competitive with state-of-the-art methods in terms of speed and accuracy.

  4. Accurate Prediction of Docked Protein Structure Similarity.

    PubMed

    Akbal-Delibas, Bahar; Pomplun, Marc; Haspel, Nurit

    2015-09-01

    One of the major challenges for protein-protein docking methods is to accurately discriminate nativelike structures. The protein docking community agrees on the existence of a relationship between various favorable intermolecular interactions (e.g. Van der Waals, electrostatic, desolvation forces, etc.) and the similarity of a conformation to its native structure. Different docking algorithms often formulate this relationship as a weighted sum of selected terms and calibrate their weights against specific training data to evaluate and rank candidate structures. However, the exact form of this relationship is unknown and the accuracy of such methods is impaired by the pervasiveness of false positives. Unlike the conventional scoring functions, we propose a novel machine learning approach that not only ranks the candidate structures relative to each other but also indicates how similar each candidate is to the native conformation. We trained the AccuRMSD neural network with an extensive dataset using the back-propagation learning algorithm. Our method achieved predicting RMSDs of unbound docked complexes with 0.4Å error margin. PMID:26335807

  5. Accurate lineshape spectroscopy and the Boltzmann constant

    PubMed Central

    Truong, G.-W.; Anstie, J. D.; May, E. F.; Stace, T. M.; Luiten, A. N.

    2015-01-01

    Spectroscopy has an illustrious history delivering serendipitous discoveries and providing a stringent testbed for new physical predictions, including applications from trace materials detection, to understanding the atmospheres of stars and planets, and even constraining cosmological models. Reaching fundamental-noise limits permits optimal extraction of spectroscopic information from an absorption measurement. Here, we demonstrate a quantum-limited spectrometer that delivers high-precision measurements of the absorption lineshape. These measurements yield a very accurate measurement of the excited-state (6P1/2) hyperfine splitting in Cs, and reveals a breakdown in the well-known Voigt spectral profile. We develop a theoretical model that accounts for this breakdown, explaining the observations to within the shot-noise limit. Our model enables us to infer the thermal velocity dispersion of the Cs vapour with an uncertainty of 35 p.p.m. within an hour. This allows us to determine a value for Boltzmann's constant with a precision of 6 p.p.m., and an uncertainty of 71 p.p.m. PMID:26465085

  6. Fast and Provably Accurate Bilateral Filtering.

    PubMed

    Chaudhury, Kunal N; Dabhade, Swapnil D

    2016-06-01

    The bilateral filter is a non-linear filter that uses a range filter along with a spatial filter to perform edge-preserving smoothing of images. A direct computation of the bilateral filter requires O(S) operations per pixel, where S is the size of the support of the spatial filter. In this paper, we present a fast and provably accurate algorithm for approximating the bilateral filter when the range kernel is Gaussian. In particular, for box and Gaussian spatial filters, the proposed algorithm can cut down the complexity to O(1) per pixel for any arbitrary S . The algorithm has a simple implementation involving N+1 spatial filterings, where N is the approximation order. We give a detailed analysis of the filtering accuracy that can be achieved by the proposed approximation in relation to the target bilateral filter. This allows us to estimate the order N required to obtain a given accuracy. We also present comprehensive numerical results to demonstrate that the proposed algorithm is competitive with the state-of-the-art methods in terms of speed and accuracy. PMID:27093722

  7. How Accurate are SuperCOSMOS Positions?

    NASA Astrophysics Data System (ADS)

    Schaefer, Adam; Hunstead, Richard; Johnston, Helen

    2014-02-01

    Optical positions from the SuperCOSMOS Sky Survey have been compared in detail with accurate radio positions that define the second realisation of the International Celestial Reference Frame (ICRF2). The comparison was limited to the IIIaJ plates from the UK/AAO and Oschin (Palomar) Schmidt telescopes. A total of 1 373 ICRF2 sources was used, with the sample restricted to stellar objects brighter than BJ = 20 and Galactic latitudes |b| > 10°. Position differences showed an rms scatter of 0.16 arcsec in right ascension and declination. While overall systematic offsets were < 0.1 arcsec in each hemisphere, both the systematics and scatter were greater in the north.

  8. Accurate adiabatic correction in the hydrogen molecule

    SciTech Connect

    Pachucki, Krzysztof; Komasa, Jacek

    2014-12-14

    A new formalism for the accurate treatment of adiabatic effects in the hydrogen molecule is presented, in which the electronic wave function is expanded in the James-Coolidge basis functions. Systematic increase in the size of the basis set permits estimation of the accuracy. Numerical results for the adiabatic correction to the Born-Oppenheimer interaction energy reveal a relative precision of 10{sup −12} at an arbitrary internuclear distance. Such calculations have been performed for 88 internuclear distances in the range of 0 < R ⩽ 12 bohrs to construct the adiabatic correction potential and to solve the nuclear Schrödinger equation. Finally, the adiabatic correction to the dissociation energies of all rovibrational levels in H{sub 2}, HD, HT, D{sub 2}, DT, and T{sub 2} has been determined. For the ground state of H{sub 2} the estimated precision is 3 × 10{sup −7} cm{sup −1}, which is almost three orders of magnitude higher than that of the best previous result. The achieved accuracy removes the adiabatic contribution from the overall error budget of the present day theoretical predictions for the rovibrational levels.

  9. Accurate adiabatic correction in the hydrogen molecule

    NASA Astrophysics Data System (ADS)

    Pachucki, Krzysztof; Komasa, Jacek

    2014-12-01

    A new formalism for the accurate treatment of adiabatic effects in the hydrogen molecule is presented, in which the electronic wave function is expanded in the James-Coolidge basis functions. Systematic increase in the size of the basis set permits estimation of the accuracy. Numerical results for the adiabatic correction to the Born-Oppenheimer interaction energy reveal a relative precision of 10-12 at an arbitrary internuclear distance. Such calculations have been performed for 88 internuclear distances in the range of 0 < R ⩽ 12 bohrs to construct the adiabatic correction potential and to solve the nuclear Schrödinger equation. Finally, the adiabatic correction to the dissociation energies of all rovibrational levels in H2, HD, HT, D2, DT, and T2 has been determined. For the ground state of H2 the estimated precision is 3 × 10-7 cm-1, which is almost three orders of magnitude higher than that of the best previous result. The achieved accuracy removes the adiabatic contribution from the overall error budget of the present day theoretical predictions for the rovibrational levels.

  10. MEMS accelerometers in accurate mount positioning systems

    NASA Astrophysics Data System (ADS)

    Mészáros, László; Pál, András.; Jaskó, Attila

    2014-07-01

    In order to attain precise, accurate and stateless positioning of telescope mounts we apply microelectromechanical accelerometer systems (also known as MEMS accelerometers). In common practice, feedback from the mount position is provided by electronic, optical or magneto-mechanical systems or via real-time astrometric solution based on the acquired images. Hence, MEMS-based systems are completely independent from these mechanisms. Our goal is to investigate the advantages and challenges of applying such devices and to reach the sub-arcminute range { that is well smaller than the field-of-view of conventional imaging telescope systems. We present how this sub-arcminute accuracy can be achieved with very cheap MEMS sensors. Basically, these sensors yield raw output within an accuracy of a few degrees. We show what kind of calibration procedures could exploit spherical and cylindrical constraints between accelerometer output channels in order to achieve the previously mentioned accuracy level. We also demonstrate how can our implementation be inserted in a telescope control system. Although this attainable precision is less than both the resolution of telescope mount drive mechanics and the accuracy of astrometric solutions, the independent nature of attitude determination could significantly increase the reliability of autonomous or remotely operated astronomical observations.

  11. Accurate, reliable prototype earth horizon sensor head

    NASA Technical Reports Server (NTRS)

    Schwarz, F.; Cohen, H.

    1973-01-01

    The design and performance is described of an accurate and reliable prototype earth sensor head (ARPESH). The ARPESH employs a detection logic 'locator' concept and horizon sensor mechanization which should lead to high accuracy horizon sensing that is minimally degraded by spatial or temporal variations in sensing attitude from a satellite in orbit around the earth at altitudes in the 500 km environ 1,2. An accuracy of horizon location to within 0.7 km has been predicted, independent of meteorological conditions. This corresponds to an error of 0.015 deg-at 500 km altitude. Laboratory evaluation of the sensor indicates that this accuracy is achieved. First, the basic operating principles of ARPESH are described; next, detailed design and construction data is presented and then performance of the sensor under laboratory conditions in which the sensor is installed in a simulator that permits it to scan over a blackbody source against background representing the earth space interface for various equivalent plant temperatures.

  12. Accurate lineshape spectroscopy and the Boltzmann constant.

    PubMed

    Truong, G-W; Anstie, J D; May, E F; Stace, T M; Luiten, A N

    2015-01-01

    Spectroscopy has an illustrious history delivering serendipitous discoveries and providing a stringent testbed for new physical predictions, including applications from trace materials detection, to understanding the atmospheres of stars and planets, and even constraining cosmological models. Reaching fundamental-noise limits permits optimal extraction of spectroscopic information from an absorption measurement. Here, we demonstrate a quantum-limited spectrometer that delivers high-precision measurements of the absorption lineshape. These measurements yield a very accurate measurement of the excited-state (6P1/2) hyperfine splitting in Cs, and reveals a breakdown in the well-known Voigt spectral profile. We develop a theoretical model that accounts for this breakdown, explaining the observations to within the shot-noise limit. Our model enables us to infer the thermal velocity dispersion of the Cs vapour with an uncertainty of 35 p.p.m. within an hour. This allows us to determine a value for Boltzmann's constant with a precision of 6 p.p.m., and an uncertainty of 71 p.p.m. PMID:26465085

  13. Fast and Accurate Exhaled Breath Ammonia Measurement

    PubMed Central

    Solga, Steven F.; Mudalel, Matthew L.; Spacek, Lisa A.; Risby, Terence H.

    2014-01-01

    This exhaled breath ammonia method uses a fast and highly sensitive spectroscopic method known as quartz enhanced photoacoustic spectroscopy (QEPAS) that uses a quantum cascade based laser. The monitor is coupled to a sampler that measures mouth pressure and carbon dioxide. The system is temperature controlled and specifically designed to address the reactivity of this compound. The sampler provides immediate feedback to the subject and the technician on the quality of the breath effort. Together with the quick response time of the monitor, this system is capable of accurately measuring exhaled breath ammonia representative of deep lung systemic levels. Because the system is easy to use and produces real time results, it has enabled experiments to identify factors that influence measurements. For example, mouth rinse and oral pH reproducibly and significantly affect results and therefore must be controlled. Temperature and mode of breathing are other examples. As our understanding of these factors evolves, error is reduced, and clinical studies become more meaningful. This system is very reliable and individual measurements are inexpensive. The sampler is relatively inexpensive and quite portable, but the monitor is neither. This limits options for some clinical studies and provides rational for future innovations. PMID:24962141

  14. Global militarization

    SciTech Connect

    Wallensteen, P.; Galtung, J.; Portales, C.

    1985-01-01

    This book contains 10 chapters. Some of the titles are: Military Formations and Social Formations: A Structural Analysis; Global Conflict Formations: Present Developments and Future Directions; War and the Power of Warmakers in Western Europe and Elsewhere, 1600-1980; and The Urban Type of Society and International War.

  15. Global Warming?

    ERIC Educational Resources Information Center

    Eichman, Julia Christensen; Brown, Jeff A.

    1994-01-01

    Presents information and data on an experiment designed to test whether different atmosphere compositions are affected by light and temperature during both cooling and heating. Although flawed, the experiment should help students appreciate the difficulties that researchers face when trying to find evidence of global warming. (PR)

  16. Global Education.

    ERIC Educational Resources Information Center

    McCoubrey, Sharon

    1994-01-01

    This theme issue focuses on topics related to global issues. (1) "Recycling for Art Projects" (Wendy Stephenson) gives an argument for recycling in the art classroom; (2) "Winds of Change: Tradition and Innovation in Circumpolar Art" (Bill Zuk and Robert Dalton) includes profiles of Alaskan Yupik artist, Larry Beck, who creates art from recycled…

  17. Campus Global.

    ERIC Educational Resources Information Center

    Sort, Josep

    2003-01-01

    Describes the development of the Campus Global portal at a public university in Spain. The project aimed to change the ways in which the university community worked, taught, and learned. Examines how the project was carried out, the transformations it instigated inside the organization, the improvements it has brought about, and the current state…

  18. Accurate orbit propagation with planetary close encounters

    NASA Astrophysics Data System (ADS)

    Baù, Giulio; Milani Comparetti, Andrea; Guerra, Francesca

    2015-08-01

    We tackle the problem of accurately propagating the motion of those small bodies that undergo close approaches with a planet. The literature is lacking on this topic and the reliability of the numerical results is not sufficiently discussed. The high-frequency components of the perturbation generated by a close encounter makes the propagation particularly challenging both from the point of view of the dynamical stability of the formulation and the numerical stability of the integrator. In our approach a fixed step-size and order multistep integrator is combined with a regularized formulation of the perturbed two-body problem. When the propagated object enters the region of influence of a celestial body, the latter becomes the new primary body of attraction. Moreover, the formulation and the step-size will also be changed if necessary. We present: 1) the restarter procedure applied to the multistep integrator whenever the primary body is changed; 2) new analytical formulae for setting the step-size (given the order of the multistep, formulation and initial osculating orbit) in order to control the accumulation of the local truncation error and guarantee the numerical stability during the propagation; 3) a new definition of the region of influence in the phase space. We test the propagator with some real asteroids subject to the gravitational attraction of the planets, the Yarkovsky and relativistic perturbations. Our goal is to show that the proposed approach improves the performance of both the propagator implemented in the OrbFit software package (which is currently used by the NEODyS service) and of the propagator represented by a variable step-size and order multistep method combined with Cowell's formulation (i.e. direct integration of position and velocity in either the physical or a fictitious time).

  19. How flatbed scanners upset accurate film dosimetry.

    PubMed

    van Battum, L J; Huizenga, H; Verdaasdonk, R M; Heukelom, S

    2016-01-21

    Film is an excellent dosimeter for verification of dose distributions due to its high spatial resolution. Irradiated film can be digitized with low-cost, transmission, flatbed scanners. However, a disadvantage is their lateral scan effect (LSE): a scanner readout change over its lateral scan axis. Although anisotropic light scattering was presented as the origin of the LSE, this paper presents an alternative cause. Hereto, LSE for two flatbed scanners (Epson 1680 Expression Pro and Epson 10000XL), and Gafchromic film (EBT, EBT2, EBT3) was investigated, focused on three effects: cross talk, optical path length and polarization. Cross talk was examined using triangular sheets of various optical densities. The optical path length effect was studied using absorptive and reflective neutral density filters with well-defined optical characteristics (OD range 0.2-2.0). Linear polarizer sheets were used to investigate light polarization on the CCD signal in absence and presence of (un)irradiated Gafchromic film. Film dose values ranged between 0.2 to 9 Gy, i.e. an optical density range between 0.25 to 1.1. Measurements were performed in the scanner's transmission mode, with red-green-blue channels. LSE was found to depend on scanner construction and film type. Its magnitude depends on dose: for 9 Gy increasing up to 14% at maximum lateral position. Cross talk was only significant in high contrast regions, up to 2% for very small fields. The optical path length effect introduced by film on the scanner causes 3% for pixels in the extreme lateral position. Light polarization due to film and the scanner's optical mirror system is the main contributor, different in magnitude for the red, green and blue channel. We concluded that any Gafchromic EBT type film scanned with a flatbed scanner will face these optical effects. Accurate dosimetry requires correction of LSE, therefore, determination of the LSE per color channel and dose delivered to the film. PMID:26689962

  20. Accurate paleointensities - the multi-method approach

    NASA Astrophysics Data System (ADS)

    de Groot, Lennart

    2016-04-01

    The accuracy of models describing rapid changes in the geomagnetic field over the past millennia critically depends on the availability of reliable paleointensity estimates. Over the past decade methods to derive paleointensities from lavas (the only recorder of the geomagnetic field that is available all over the globe and through geologic times) have seen significant improvements and various alternative techniques were proposed. The 'classical' Thellier-style approach was optimized and selection criteria were defined in the 'Standard Paleointensity Definitions' (Paterson et al, 2014). The Multispecimen approach was validated and the importance of additional tests and criteria to assess Multispecimen results must be emphasized. Recently, a non-heating, relative paleointensity technique was proposed -the pseudo-Thellier protocol- which shows great potential in both accuracy and efficiency, but currently lacks a solid theoretical underpinning. Here I present work using all three of the aforementioned paleointensity methods on suites of young lavas taken from the volcanic islands of Hawaii, La Palma, Gran Canaria, Tenerife, and Terceira. Many of the sampled cooling units are <100 years old, the actual field strength at the time of cooling is therefore reasonably well known. Rather intuitively, flows that produce coherent results from two or more different paleointensity methods yield the most accurate estimates of the paleofield. Furthermore, the results for some flows pass the selection criteria for one method, but fail in other techniques. Scrutinizing and combing all acceptable results yielded reliable paleointensity estimates for 60-70% of all sampled cooling units - an exceptionally high success rate. This 'multi-method paleointensity approach' therefore has high potential to provide the much-needed paleointensities to improve geomagnetic field models for the Holocene.

  1. Important Nearby Galaxies without Accurate Distances

    NASA Astrophysics Data System (ADS)

    McQuinn, Kristen

    2014-10-01

    The Spitzer Infrared Nearby Galaxies Survey (SINGS) and its offspring programs (e.g., THINGS, HERACLES, KINGFISH) have resulted in a fundamental change in our view of star formation and the ISM in galaxies, and together they represent the most complete multi-wavelength data set yet assembled for a large sample of nearby galaxies. These great investments of observing time have been dedicated to the goal of understanding the interstellar medium, the star formation process, and, more generally, galactic evolution at the present epoch. Nearby galaxies provide the basis for which we interpret the distant universe, and the SINGS sample represents the best studied nearby galaxies.Accurate distances are fundamental to interpreting observations of galaxies. Surprisingly, many of the SINGS spiral galaxies have numerous distance estimates resulting in confusion. We can rectify this situation for 8 of the SINGS spiral galaxies within 10 Mpc at a very low cost through measurements of the tip of the red giant branch. The proposed observations will provide an accuracy of better than 0.1 in distance modulus. Our sample includes such well known galaxies as M51 (the Whirlpool), M63 (the Sunflower), M104 (the Sombrero), and M74 (the archetypal grand design spiral).We are also proposing coordinated parallel WFC3 UV observations of the central regions of the galaxies, rich with high-mass UV-bright stars. As a secondary science goal we will compare the resolved UV stellar populations with integrated UV emission measurements used in calibrating star formation rates. Our observations will complement the growing HST UV atlas of high resolution images of nearby galaxies.

  2. Towards Accurate Application Characterization for Exascale (APEX)

    SciTech Connect

    Hammond, Simon David

    2015-09-01

    Sandia National Laboratories has been engaged in hardware and software codesign activities for a number of years, indeed, it might be argued that prototyping of clusters as far back as the CPLANT machines and many large capability resources including ASCI Red and RedStorm were examples of codesigned solutions. As the research supporting our codesign activities has moved closer to investigating on-node runtime behavior a nature hunger has grown for detailed analysis of both hardware and algorithm performance from the perspective of low-level operations. The Application Characterization for Exascale (APEX) LDRD was a project concieved of addressing some of these concerns. Primarily the research was to intended to focus on generating accurate and reproducible low-level performance metrics using tools that could scale to production-class code bases. Along side this research was an advocacy and analysis role associated with evaluating tools for production use, working with leading industry vendors to develop and refine solutions required by our code teams and to directly engage with production code developers to form a context for the application analysis and a bridge to the research community within Sandia. On each of these accounts significant progress has been made, particularly, as this report will cover, in the low-level analysis of operations for important classes of algorithms. This report summarizes the development of a collection of tools under the APEX research program and leaves to other SAND and L2 milestone reports the description of codesign progress with Sandia’s production users/developers.

  3. How flatbed scanners upset accurate film dosimetry

    NASA Astrophysics Data System (ADS)

    van Battum, L. J.; Huizenga, H.; Verdaasdonk, R. M.; Heukelom, S.

    2016-01-01

    Film is an excellent dosimeter for verification of dose distributions due to its high spatial resolution. Irradiated film can be digitized with low-cost, transmission, flatbed scanners. However, a disadvantage is their lateral scan effect (LSE): a scanner readout change over its lateral scan axis. Although anisotropic light scattering was presented as the origin of the LSE, this paper presents an alternative cause. Hereto, LSE for two flatbed scanners (Epson 1680 Expression Pro and Epson 10000XL), and Gafchromic film (EBT, EBT2, EBT3) was investigated, focused on three effects: cross talk, optical path length and polarization. Cross talk was examined using triangular sheets of various optical densities. The optical path length effect was studied using absorptive and reflective neutral density filters with well-defined optical characteristics (OD range 0.2-2.0). Linear polarizer sheets were used to investigate light polarization on the CCD signal in absence and presence of (un)irradiated Gafchromic film. Film dose values ranged between 0.2 to 9 Gy, i.e. an optical density range between 0.25 to 1.1. Measurements were performed in the scanner’s transmission mode, with red-green-blue channels. LSE was found to depend on scanner construction and film type. Its magnitude depends on dose: for 9 Gy increasing up to 14% at maximum lateral position. Cross talk was only significant in high contrast regions, up to 2% for very small fields. The optical path length effect introduced by film on the scanner causes 3% for pixels in the extreme lateral position. Light polarization due to film and the scanner’s optical mirror system is the main contributor, different in magnitude for the red, green and blue channel. We concluded that any Gafchromic EBT type film scanned with a flatbed scanner will face these optical effects. Accurate dosimetry requires correction of LSE, therefore, determination of the LSE per color channel and dose delivered to the film.

  4. Accurate simulation of optical properties in dyes.

    PubMed

    Jacquemin, Denis; Perpète, Eric A; Ciofini, Ilaria; Adamo, Carlo

    2009-02-17

    Since Antiquity, humans have produced and commercialized dyes. To this day, extraction of natural dyes often requires lengthy and costly procedures. In the 19th century, global markets and new industrial products drove a significant effort to synthesize artificial dyes, characterized by low production costs, huge quantities, and new optical properties (colors). Dyes that encompass classes of molecules absorbing in the UV-visible part of the electromagnetic spectrum now have a wider range of applications, including coloring (textiles, food, paintings), energy production (photovoltaic cells, OLEDs), or pharmaceuticals (diagnostics, drugs). Parallel to the growth in dye applications, researchers have increased their efforts to design and synthesize new dyes to customize absorption and emission properties. In particular, dyes containing one or more metallic centers allow for the construction of fairly sophisticated systems capable of selectively reacting to light of a given wavelength and behaving as molecular devices (photochemical molecular devices, PMDs).Theoretical tools able to predict and interpret the excited-state properties of organic and inorganic dyes allow for an efficient screening of photochemical centers. In this Account, we report recent developments defining a quantitative ab initio protocol (based on time-dependent density functional theory) for modeling dye spectral properties. In particular, we discuss the importance of several parameters, such as the methods used for electronic structure calculations, solvent effects, and statistical treatments. In addition, we illustrate the performance of such simulation tools through case studies. We also comment on current weak points of these methods and ways to improve them. PMID:19113946

  5. Progress in fast, accurate multi-scale climate simulations

    DOE PAGESBeta

    Collins, W. D.; Johansen, H.; Evans, K. J.; Woodward, C. S.; Caldwell, P. M.

    2015-06-01

    We present a survey of physical and computational techniques that have the potential to contribute to the next generation of high-fidelity, multi-scale climate simulations. Examples of the climate science problems that can be investigated with more depth with these computational improvements include the capture of remote forcings of localized hydrological extreme events, an accurate representation of cloud features over a range of spatial and temporal scales, and parallel, large ensembles of simulations to more effectively explore model sensitivities and uncertainties. Numerical techniques, such as adaptive mesh refinement, implicit time integration, and separate treatment of fast physical time scales are enablingmore » improved accuracy and fidelity in simulation of dynamics and allowing more complete representations of climate features at the global scale. At the same time, partnerships with computer science teams have focused on taking advantage of evolving computer architectures such as many-core processors and GPUs. As a result, approaches which were previously considered prohibitively costly have become both more efficient and scalable. In combination, progress in these three critical areas is poised to transform climate modeling in the coming decades.« less

  6. Progress in fast, accurate multi-scale climate simulations

    SciTech Connect

    Collins, W. D.; Johansen, H.; Evans, K. J.; Woodward, C. S.; Caldwell, P. M.

    2015-06-01

    We present a survey of physical and computational techniques that have the potential to contribute to the next generation of high-fidelity, multi-scale climate simulations. Examples of the climate science problems that can be investigated with more depth with these computational improvements include the capture of remote forcings of localized hydrological extreme events, an accurate representation of cloud features over a range of spatial and temporal scales, and parallel, large ensembles of simulations to more effectively explore model sensitivities and uncertainties. Numerical techniques, such as adaptive mesh refinement, implicit time integration, and separate treatment of fast physical time scales are enabling improved accuracy and fidelity in simulation of dynamics and allowing more complete representations of climate features at the global scale. At the same time, partnerships with computer science teams have focused on taking advantage of evolving computer architectures such as many-core processors and GPUs. As a result, approaches which were previously considered prohibitively costly have become both more efficient and scalable. In combination, progress in these three critical areas is poised to transform climate modeling in the coming decades.

  7. Progress in Fast, Accurate Multi-scale Climate Simulations

    SciTech Connect

    Collins, William D; Johansen, Hans; Evans, Katherine J; Woodward, Carol S.; Caldwell, Peter

    2015-01-01

    We present a survey of physical and computational techniques that have the potential to con- tribute to the next generation of high-fidelity, multi-scale climate simulations. Examples of the climate science problems that can be investigated with more depth include the capture of remote forcings of localized hydrological extreme events, an accurate representation of cloud features over a range of spatial and temporal scales, and parallel, large ensembles of simulations to more effectively explore model sensitivities and uncertainties. Numerical techniques, such as adaptive mesh refinement, implicit time integration, and separate treatment of fast physical time scales are enabling improved accuracy and fidelity in simulation of dynamics and allow more complete representations of climate features at the global scale. At the same time, part- nerships with computer science teams have focused on taking advantage of evolving computer architectures, such as many-core processors and GPUs, so that these approaches which were previously considered prohibitively costly have become both more efficient and scalable. In combination, progress in these three critical areas is poised to transform climate modeling in the coming decades.

  8. Accurate inference of local phased ancestry of modern admixed populations.

    PubMed

    Ma, Yamin; Zhao, Jian; Wong, Jian-Syuan; Ma, Li; Li, Wenzhi; Fu, Guoxing; Xu, Wei; Zhang, Kui; Kittles, Rick A; Li, Yun; Song, Qing

    2014-01-01

    Population stratification is a growing concern in genetic-association studies. Averaged ancestry at the genome level (global ancestry) is insufficient for detecting the population substructures and correcting population stratifications in association studies. Local and phase stratification are needed for human genetic studies, but current technologies cannot be applied on the entire genome data due to various technical caveats. Here we developed a novel approach (aMAP, ancestry of Modern Admixed Populations) for inferring local phased ancestry. It took about 3 seconds on a desktop computer to finish a local ancestry analysis for each human genome with 1.4-million SNPs. This method also exhibits the scalability to larger datasets with respect to the number of SNPs, the number of samples, and the size of reference panels. It can detect the lack of the proxy of reference panels. The accuracy was 99.4%. The aMAP software has a capacity for analyzing 6-way admixed individuals. As the biomedical community continues to expand its efforts to increase the representation of diverse populations, and as the number of large whole-genome sequence datasets continues to grow rapidly, there is an increasing demand on rapid and accurate local ancestry analysis in genetics, pharmacogenomics, population genetics, and clinical diagnosis. PMID:25052506

  9. Accurate theoretical chemistry with coupled pair models.

    PubMed

    Neese, Frank; Hansen, Andreas; Wennmohs, Frank; Grimme, Stefan

    2009-05-19

    Quantum chemistry has found its way into the everyday work of many experimental chemists. Calculations can predict the outcome of chemical reactions, afford insight into reaction mechanisms, and be used to interpret structure and bonding in molecules. Thus, contemporary theory offers tremendous opportunities in experimental chemical research. However, even with present-day computers and algorithms, we cannot solve the many particle Schrodinger equation exactly; inevitably some error is introduced in approximating the solutions of this equation. Thus, the accuracy of quantum chemical calculations is of critical importance. The affordable accuracy depends on molecular size and particularly on the total number of atoms: for orientation, ethanol has 9 atoms, aspirin 21 atoms, morphine 40 atoms, sildenafil 63 atoms, paclitaxel 113 atoms, insulin nearly 800 atoms, and quaternary hemoglobin almost 12,000 atoms. Currently, molecules with up to approximately 10 atoms can be very accurately studied by coupled cluster (CC) theory, approximately 100 atoms with second-order Møller-Plesset perturbation theory (MP2), approximately 1000 atoms with density functional theory (DFT), and beyond that number with semiempirical quantum chemistry and force-field methods. The overwhelming majority of present-day calculations in the 100-atom range use DFT. Although these methods have been very successful in quantum chemistry, they do not offer a well-defined hierarchy of calculations that allows one to systematically converge to the correct answer. Recently a number of rather spectacular failures of DFT methods have been found-even for seemingly simple systems such as hydrocarbons, fueling renewed interest in wave function-based methods that incorporate the relevant physics of electron correlation in a more systematic way. Thus, it would be highly desirable to fill the gap between 10 and 100 atoms with highly correlated ab initio methods. We have found that one of the earliest (and now

  10. Panwapa: Global Kids, Global Connections

    ERIC Educational Resources Information Center

    Berson, Ilene R.; Berson, Michael J.

    2009-01-01

    Panwapa, created by the Sesame Street Workshop of PBS, is an example of an initiative on the Internet designed to enhance students' learning by exposing them to global communities. Panwapa means "Here on Earth" in Tshiluba, a Bantu language spoken in the Democratic Republic of Congo. At the Panwapa website, www.panwapa.org, children aged four to…

  11. Going Global

    ERIC Educational Resources Information Center

    Boulard, Garry

    2010-01-01

    In a move to increase its out-of-state and international student enrollment, officials at the University of Iowa are stepping up their global recruitment efforts--even in the face of criticism that the school may be losing sight of its mission. The goal is to increase enrollment across the board, with both in-state as well as out-of-state and…

  12. Global Arrays

    SciTech Connect

    2006-02-23

    The Global Arrays (GA) toolkit provides an efficient and portable “shared-memory” programming interface for distributed-memory computers. Each process in a MIMD parallel program can asynchronously access logical blocks of physically distributed dense multi-dimensional arrays, without need for explicit cooperation by other processes. Unlike other shared-memory environments, the GA model exposes to the programmer the non-uniform memory access (NUMA) characteristics of the high performance computers and acknowledges that access to a remote portion of the shared data is slower than to the local portion. The locality information for the shared data is available, and a direct access to the local portions of shared data is provided. Global Arrays have been designed to complement rather than substitute for the message-passing programming model. The programmer is free to use both the shared-memory and message-passing paradigms in the same program, and to take advantage of existing message-passing software libraries. Global Arrays are compatible with the Message Passing Interface (MPI).

  13. Global Arrays

    2006-02-23

    The Global Arrays (GA) toolkit provides an efficient and portable “shared-memory” programming interface for distributed-memory computers. Each process in a MIMD parallel program can asynchronously access logical blocks of physically distributed dense multi-dimensional arrays, without need for explicit cooperation by other processes. Unlike other shared-memory environments, the GA model exposes to the programmer the non-uniform memory access (NUMA) characteristics of the high performance computers and acknowledges that access to a remote portion of the sharedmore » data is slower than to the local portion. The locality information for the shared data is available, and a direct access to the local portions of shared data is provided. Global Arrays have been designed to complement rather than substitute for the message-passing programming model. The programmer is free to use both the shared-memory and message-passing paradigms in the same program, and to take advantage of existing message-passing software libraries. Global Arrays are compatible with the Message Passing Interface (MPI).« less

  14. Global Ionosphere Radio Observatory

    NASA Astrophysics Data System (ADS)

    Galkin, I. A.; Reinisch, B. W.; Huang, X. A.

    2014-12-01

    The Global Ionosphere Radio Observatory (GIRO) comprises a network of ground-based high-frequency vertical sounding sensors, ionosondes, with instrument installations in 27 countries and a central Lowell GIRO Data Center (LGDC) for data acquisition and assimilation, including 46 real-time data streams as of August 2014. The LGDC implemented a suite of technologies for post-processing, modeling, analysis, and dissemination of the acquired and derived data products, including: (1) IRI-based Real-time Assimilative Model, "IRTAM", that builds and publishes every 15-minutes an updated "global weather" map of the peak density and height in the ionosphere, as well as a map of deviations from the classic IRI climate; (2) Global Assimilative Model of Bottomside Ionosphere Timelines (GAMBIT) Database and Explorer holding 15 years worth of IRTAM computed maps at 15 minute cadence;. (3) 17+ million ionograms and matching ionogram-derived records of URSI-standard ionospheric characteristics and vertical profiles of electron density; (4) 10+ million records of the Doppler Skymaps showing spatial distributions over the GIRO locations and plasma drifts; (5) Data and software for Traveling Ionospheric Disturbance (TID) diagnostics; and (6) HR2006 ray tracing software mated to the "realistic" IRTAM ionosphere. In cooperation with the URSI Ionosonde Network Advisory Group (INAG), the LGDC promotes cooperative agreements with the ionosonde observatories of the world to accept and process real-time data of HF radio monitoring of the ionosphere, and to promote a variety of investigations that benefit from the global-scale, prompt, detailed, and accurate descriptions of the ionospheric variability.

  15. Ocean biogeochemical response to phytoplankton-light feedback in a global model

    NASA Astrophysics Data System (ADS)

    Manizza, Manfredi; Le QuéRé, Corinne; Watson, Andrew J.; Buitenhuis, Erik T.

    2008-10-01

    Oceanic phytoplankton, absorbing solar radiation, can influence the bio-optical properties of seawater and hence upper ocean physics. We include this process in a global ocean general circulation model (OGCM) coupled to a dynamic green ocean model (DGOM) based on multiple plankton functional types (PFT). We not only study the impact of this process on ocean physics but we also explore the biogeochemical response due to this biophysical feedback. The phytoplankton-light feedback (PLF) impacts the dynamics of the upper tropical and subtropical oceans. The change in circulation enhances both the vertical supply in the tropics and the lateral supply of nutrients from the tropics to the subtropics boosting the subtropical productivity by up to 60 gC m-2 a-1. Physical changes, due to the PLF, impact on light and nutrient availability causing shifts in the ocean ecosystems. In the extratropics, increased stratification favors calcifiers (by up to ˜8%) at the expense of mixed phytoplankton. In the Southern Ocean, silicifiers increase their biomass (by up to ˜10%) because of the combined alleviation of iron and light limitation. The PLF has a small effect globally on air-sea fluxes of carbon dioxide (CO2, 72 TmolC a-1 outgassing) and oxygen (O2, 46 TmolO2 a-1 ingassing) because changes in biogeochemical processes (primary production, biogenic calcification, and export production) highly vary regionally and can also oppose each other. From our study it emerges that the main impact of the PLF is an amplification of the seasonal cycle of physical and biogeochemical properties of the high-latitude oceans mostly driven by the amplification of the SST seasonal cycle.

  16. The Global Positioning System

    USGS Publications Warehouse

    U.S. Geological Survey

    1999-01-01

    The Global Positioning System (GPS) is a constellation of navigation satellites called Navigation Satellite Timing And Ranging (NAVSTAR), maintained by the U.S. Department of Defense. Many outdoor enthusiasts recognize that a handheld GPS receiver can be an accurate tool for determining their location on the terrain. The GPS receiver helps determine locations on the Earth's surface by collecting signals from three or more satellites through a process called triangulation. Identifying a location on the Earth is more useful if you also know about the surrounding topographic conditions. Using a topographic map with the GPS receiver provides important information about features of the surrounding terrain and can help you plot an effective route from one location to another.

  17. A spectroscopic transfer standard for accurate atmospheric CO measurements

    NASA Astrophysics Data System (ADS)

    Nwaboh, Javis A.; Li, Gang; Serdyukov, Anton; Werhahn, Olav; Ebert, Volker

    2016-04-01

    Atmospheric carbon monoxide (CO) is a precursor of essential climate variables and has an indirect effect for enhancing global warming. Accurate and reliable measurements of atmospheric CO concentration are becoming indispensable. WMO-GAW reports states a compatibility goal of ±2 ppb for atmospheric CO concentration measurements. Therefore, the EMRP-HIGHGAS (European metrology research program - high-impact greenhouse gases) project aims at developing spectroscopic transfer standards for CO concentration measurements to meet this goal. A spectroscopic transfer standard would provide results that are directly traceable to the SI, can be very useful for calibration of devices operating in the field, and could complement classical gas standards in the field where calibration gas mixtures in bottles often are not accurate, available or stable enough [1][2]. Here, we present our new direct tunable diode laser absorption spectroscopy (dTDLAS) sensor capable of performing absolute ("calibration free") CO concentration measurements, and being operated as a spectroscopic transfer standard. To achieve the compatibility goal stated by WMO for CO concentration measurements and ensure the traceability of the final concentration results, traceable spectral line data especially line intensities with appropriate uncertainties are needed. Therefore, we utilize our new high-resolution Fourier-transform infrared (FTIR) spectroscopy CO line data for the 2-0 band, with significantly reduced uncertainties, for the dTDLAS data evaluation. Further, we demonstrate the capability of our sensor for atmospheric CO measurements, discuss uncertainty calculation following the guide to the expression of uncertainty in measurement (GUM) principles and show that CO concentrations derived using the sensor, based on the TILSAM (traceable infrared laser spectroscopic amount fraction measurement) method, are in excellent agreement with gravimetric values. Acknowledgement Parts of this work have been

  18. IRIS: Towards an Accurate and Fast Stage Weight Prediction Method

    NASA Astrophysics Data System (ADS)

    Taponier, V.; Balu, A.

    2002-01-01

    The knowledge of the structural mass fraction (or the mass ratio) of a given stage, which affects the performance of a rocket, is essential for the analysis of new or upgraded launchers or stages, whose need is increased by the quick evolution of the space programs and by the necessity of their adaptation to the market needs. The availability of this highly scattered variable, ranging between 0.05 and 0.15, is of primary importance at the early steps of the preliminary design studies. At the start of the staging and performance studies, the lack of frozen weight data (to be obtained later on from propulsion, trajectory and sizing studies) leads to rely on rough estimates, generally derived from printed sources and adapted. When needed, a consolidation can be acquired trough a specific analysis activity involving several techniques and implying additional effort and time. The present empirical approach allows thus to get approximated values (i.e. not necessarily accurate or consistent), inducing some result inaccuracy as well as, consequently, difficulties of performance ranking for a multiple option analysis, and an increase of the processing duration. This forms a classical harsh fact of the preliminary design system studies, insufficiently discussed to date. It appears therefore highly desirable to have, for all the evaluation activities, a reliable, fast and easy-to-use weight or mass fraction prediction method. Additionally, the latter should allow for a pre selection of the alternative preliminary configurations, making possible a global system approach. For that purpose, an attempt at modeling has been undertaken, whose objective was the determination of a parametric formulation of the mass fraction, to be expressed from a limited number of parameters available at the early steps of the project. It is based on the innovative use of a statistical method applicable to a variable as a function of several independent parameters. A specific polynomial generator

  19. Robust, accurate and fast automatic segmentation of the spinal cord.

    PubMed

    De Leener, Benjamin; Kadoury, Samuel; Cohen-Adad, Julien

    2014-09-01

    Spinal cord segmentation provides measures of atrophy and facilitates group analysis via inter-subject correspondence. Automatizing this procedure enables studies with large throughput and minimizes user bias. Although several automatic segmentation methods exist, they are often restricted in terms of image contrast and field-of-view. This paper presents a new automatic segmentation method (PropSeg) optimized for robustness, accuracy and speed. The algorithm is based on the propagation of a deformable model and is divided into three parts: firstly, an initialization step detects the spinal cord position and orientation using a circular Hough transform on multiple axial slices rostral and caudal to the starting plane and builds an initial elliptical tubular mesh. Secondly, a low-resolution deformable model is propagated along the spinal cord. To deal with highly variable contrast levels between the spinal cord and the cerebrospinal fluid, the deformation is coupled with a local contrast-to-noise adaptation at each iteration. Thirdly, a refinement process and a global deformation are applied on the propagated mesh to provide an accurate segmentation of the spinal cord. Validation was performed in 15 healthy subjects and two patients with spinal cord injury, using T1- and T2-weighted images of the entire spinal cord and on multiecho T2*-weighted images. Our method was compared against manual segmentation and against an active surface method. Results show high precision for all the MR sequences. Dice coefficients were 0.9 for the T1- and T2-weighted cohorts and 0.86 for the T2*-weighted images. The proposed method runs in less than 1min on a normal computer and can be used to quantify morphological features such as cross-sectional area along the whole spinal cord. PMID:24780696

  20. Fast and Accurate Detection of Multiple Quantitative Trait Loci

    PubMed Central

    Nettelblad, Carl; Holmgren, Sverker

    2013-01-01

    Abstract We present a new computational scheme that enables efficient and reliable quantitative trait loci (QTL) scans for experimental populations. Using a standard brute-force exhaustive search effectively prohibits accurate QTL scans involving more than two loci to be performed in practice, at least if permutation testing is used to determine significance. Some more elaborate global optimization approaches, for example, DIRECT have been adopted earlier to QTL search problems. Dramatic speedups have been reported for high-dimensional scans. However, since a heuristic termination criterion must be used in these types of algorithms, the accuracy of the optimization process cannot be guaranteed. Indeed, earlier results show that a small bias in the significance thresholds is sometimes introduced. Our new optimization scheme, PruneDIRECT, is based on an analysis leading to a computable (Lipschitz) bound on the slope of a transformed objective function. The bound is derived for both infinite- and finite-size populations. Introducing a Lipschitz bound in DIRECT leads to an algorithm related to classical Lipschitz optimization. Regions in the search space can be permanently excluded (pruned) during the optimization process. Heuristic termination criteria can thus be avoided. Hence, PruneDIRECT has a well-defined error bound and can in practice be guaranteed to be equivalent to a corresponding exhaustive search. We present simulation results that show that for simultaneous mapping of three QTLS using permutation testing, PruneDIRECT is typically more than 50 times faster than exhaustive search. The speedup is higher for stronger QTL. This could be used to quickly detect strong candidate eQTL networks. PMID:23919387

  1. 77 FR 65244 - In the Matter of Fearless International, Inc., Glassmaster Company, Global Entertainment Holdings...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-25

    ... From the Federal Register Online via the Government Publishing Office SECURITIES AND EXCHANGE COMMISSION In the Matter of Fearless International, Inc., Glassmaster Company, Global Entertainment Holdings... of current and accurate information concerning the securities of Global Entertainment...

  2. Global teaching of global seismology

    NASA Astrophysics Data System (ADS)

    Stein, S.; Wysession, M.

    2005-12-01

    Our recent textbook, Introduction to Seismology, Earthquakes, & Earth Structure (Blackwell, 2003) is used in many countries. Part of the reason for this may be our deliberate attempt to write the book for an international audience. This effort appears in several ways. We stress seismology's long tradition of global data interchange. Our brief discussions of the science's history illustrate the contributions of scientists around the world. Perhaps most importantly, our discussions of earthquakes, tectonics, and seismic hazards take a global view. Many examples are from North America, whereas others are from other areas. Our view is that non-North American students should be exposed to North American examples that are type examples, and that North American students should be similarly exposed to examples elsewhere. For example, we illustrate how the Euler vector geometry changes a plate boundary from spreading, to strike-slip, to convergence using both the Pacific-North America boundary from the Gulf of California to Alaska and the Eurasia-Africa boundary from the Azores to the Mediterranean. We illustrate diffuse plate boundary zones using western North America, the Andes, the Himalayas, the Mediterranean, and the East Africa Rift. The subduction zone discussions examine Japan, Tonga, and Chile. We discuss significant earthquakes both in the U.S. and elsewhere, and explore hazard mitigation issues in different contexts. Both comments from foreign colleagues and our experience lecturing overseas indicate that this approach works well. Beyond the specifics of our text, we believe that such a global approach is facilitated by the international traditions of the earth sciences and the world youth culture that gives students worldwide common culture. For example, a video of the scene in New Madrid, Missouri that arose from a nonsensical earthquake prediction in 1990 elicits similar responses from American and European students.

  3. Global precipitation measurement (GPM)

    NASA Astrophysics Data System (ADS)

    Neeck, Steven P.; Flaming, Gilbert M.; Adams, W. James; Smith, Eric A.

    2001-12-01

    The National Aeronautics and Space Administration (NASA) is studying options for future space-based missions for the EOS Follow-on Era (post 2003), building upon the measurements made by Pre-EOS and EOS First Series Missions. One mission under consideration is the Global Precipitation Measurement (GPM), a cooperative venture of NASA, Japan, and other international partners. GPM will capitalize on the experience of the highly successful Tropical Rainfall Measurement Mission (TRMM). Its goal is to extend the measurement of rainfall to high latitudes with high temporal frequency, providing a global data set every three hours. A reference concept has been developed consisting of an improved TRMM-like primary satellite with precipitation radar and microwave radiometer to make detailed and accurate estimates of the precipitation structure and a constellation of small satellites flying compact microwave radiometers to provide the required temporal sampling of highly variable precipitation systems. Considering that DMSP spacecraft equipped with SSMIS microwave radiometers, successor NPOESS spacecraft equipped with CMIS microwave radiometers, and other relevant international systems are expected to be in operation during the timeframe of the reference concept, the total number of small satellites required to complete the constellation will be reduced. A nominal plan is to begin implementation in FY'03 with launches in 2007. NASA is presently engaged in advanced mission studies and advanced instrument technology development related to the mission.

  4. Global Geomorphology

    NASA Technical Reports Server (NTRS)

    Douglas, I.

    1985-01-01

    Any global view of landforms must include an evaluation of the link between plate tectonics and geomorphology. To explain the broad features of the continents and ocean floors, a basic distinction between the tectogene and cratogene part of the Earth's surface must be made. The tectogene areas are those that are dominated by crustal movements, earthquakes and volcanicity at the present time and are essentially those of the great mountain belts and mid ocean ridges. Cratogene areas comprise the plate interiors, especially the old lands of Gondwanaland and Laurasia. Fundamental as this division between plate margin areas and plate interiors is, it cannot be said to be a simple case of a distinction between tectonically active and stable areas. Indeed, in terms of megageomorphology, former plate margins and tectonic activity up to 600 million years ago have to be considered.

  5. Global gamesmanship.

    PubMed

    MacMillan, Ian C; van Putten, Alexander B; McGrath, Rita Gunther

    2003-05-01

    Competition among multinationals these days is likely to be a three-dimensional game of global chess: The moves an organization makes in one market are designed to achieve goals in another in ways that aren't immediately apparent to its rivals. The authors--all management professors-call this approach "competing under strategic interdependence," or CSI. And where this interdependence exists, the complexity of the situation can quickly overwhelm ordinary analysis. Indeed, most business strategists are terrible at anticipating the consequences of interdependent choices, and they're even worse at using interdependency to their advantage. In this article, the authors offer a process for mapping the competitive landscape and anticipating how your company's moves in one market can influence its competitive interactions in others. They outline the six types of CSI campaigns--onslaughts, contests, guerrilla campaigns, feints, gambits, and harvesting--available to any multiproduct or multimarket corporation that wants to compete skillfully. They cite real-world examples such as the U.S. pricing battle Philip Morris waged with R.J. Reynolds--not to gain market share in the domestic cigarette market but to divert R.J. Reynolds's resources and attention from the opportunities Philip Morris was pursuing in Eastern Europe. And, using data they collected from their studies of consumer-products companies Procter & Gamble and Unilever, the authors describe how to create CSI tables and bubble charts that present a graphical look at the competitive landscape and that may uncover previously hidden opportunities. The CSI mapping process isn't just for global corporations, the authors explain. Smaller organizations that compete with a portfolio of products in just one national or regional market may find it just as useful for planning their next business moves. PMID:12747163

  6. Global warming

    NASA Astrophysics Data System (ADS)

    Houghton, John

    2005-06-01

    'Global warming' is a phrase that refers to the effect on the climate of human activities, in particular the burning of fossil fuels (coal, oil and gas) and large-scale deforestation, which cause emissions to the atmosphere of large amounts of 'greenhouse gases', of which the most important is carbon dioxide. Such gases absorb infrared radiation emitted by the Earth's surface and act as blankets over the surface keeping it warmer than it would otherwise be. Associated with this warming are changes of climate. The basic science of the 'greenhouse effect' that leads to the warming is well understood. More detailed understanding relies on numerical models of the climate that integrate the basic dynamical and physical equations describing the complete climate system. Many of the likely characteristics of the resulting changes in climate (such as more frequent heat waves, increases in rainfall, increase in frequency and intensity of many extreme climate events) can be identified. Substantial uncertainties remain in knowledge of some of the feedbacks within the climate system (that affect the overall magnitude of change) and in much of the detail of likely regional change. Because of its negative impacts on human communities (including for instance substantial sea-level rise) and on ecosystems, global warming is the most important environmental problem the world faces. Adaptation to the inevitable impacts and mitigation to reduce their magnitude are both necessary. International action is being taken by the world's scientific and political communities. Because of the need for urgent action, the greatest challenge is to move rapidly to much increased energy efficiency and to non-fossil-fuel energy sources.

  7. Global carbon budget 2013

    NASA Astrophysics Data System (ADS)

    Le Quéré, C.; Peters, G. P.; Andres, R. J.; Andrew, R. M.; Boden, T.; Ciais, P.; Friedlingstein, P.; Houghton, R. A.; Marland, G.; Moriarty, R.; Sitch, S.; Tans, P.; Arneth, A.; Arvanitis, A.; Bakker, D. C. E.; Bopp, L.; Canadell, J. G.; Chini, L. P.; Doney, S. C.; Harper, A.; Harris, I.; House, J. I.; Jain, A. K.; Jones, S. D.; Kato, E.; Keeling, R. F.; Klein Goldewijk, K.; Körtzinger, A.; Koven, C.; Lefèvre, N.; Omar, A.; Ono, T.; Park, G.-H.; Pfeil, B.; Poulter, B.; Raupach, M. R.; Regnier, P.; Rödenbeck, C.; Saito, S.; Schwinger, J.; Segschneider, J.; Stocker, B. D.; Tilbrook, B.; van Heuven, S.; Viovy, N.; Wanninkhof, R.; Wiltshire, A.; Zaehle, S.; Yue, C.

    2013-11-01

    Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe datasets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil-fuel combustion and cement production (EFF) are based on energy statistics, while emissions from Land-Use Change (ELUC), including deforestation, are based on combined evidence from land-cover change data, fire activity in regions undergoing deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated for the first time in this budget with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of Dynamic Global Vegetation Models. All uncertainties are reported as ± 1 sigma, reflecting the current capacity to characterise the annual estimates of each component of the global carbon budget. For the last decade available (2003-2012), EFF was 8.6 ± 0.4 GtC yr-1, ELUC 0.8 ± 0.5 GtC yr-1, GATM 4.3 ± 0.1 GtC yr-1, SOCEAN 2.6 ± 0.5 GtC yr-1, and SLAND 2.6 ± 0.8 GtC yr-1. For year 2012 alone, EFF grew to 9.7

  8. Global Albedo

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A new sensor aboard NASA?s Terra satellite is now collecting the most detailed and accurate measurements ever made of how much sunlight the Earth?s surface reflects back up into the atmosphere. By quantifying precisely our planet?s reflectivity, or albedo, the Moderate Resolution Imaging Spectroradiometer (MODIS) is helping scientists better understand and predict how various surface features influence both short-term weather patterns as well as longer-term climate trends. (Click to read the press release.) The colors in this image emphasize the albedo over the Earth?s land surfaces, ranging from 0.0 to 0.4. Areas colored red show the brightest, most reflective regions; yellows and greens are intermediate values; and blues and violets show relatively dark surfaces. White indicates where no data were available, and no albedo data are provided over the oceans. This image was produced using data composited over a 16-day period, from April 7-22, 2002. Image courtesy Crystal Schaaf, Boston University, based upon data processed by the MODIS Land Science Team

  9. Global trends

    NASA Technical Reports Server (NTRS)

    Megie, G.; Chanin, M.-L.; Ehhalt, D.; Fraser, P.; Frederick, J. F.; Gille, J. C.; Mccormick, M. P.; Schoebert, M.; Bishop, L.; Bojkov, R. D.

    1990-01-01

    Measuring trends in ozone, and most other geophysical variables, requires that a small systematic change with time be determined from signals that have large periodic and aperiodic variations. Their time scales range from the day-to-day changes due to atmospheric motions through seasonal and annual variations to 11 year cycles resulting from changes in the sun UV output. Because of the magnitude of all of these variations is not well known and highly variable, it is necessary to measure over more than one period of the variations to remove their effects. This means that at least 2 or more times the 11 year sunspot cycle. Thus, the first requirement is for a long term data record. The second related requirement is that the record be consistent. A third requirement is for reasonable global sampling, to ensure that the effects are representative of the entire Earth. The various observational methods relevant to trend detection are reviewed to characterize their quality and time and space coverage. Available data are then examined for long term trends or recent changes in ozone total content and vertical distribution, as well as related parameters such as stratospheric temperature, source gases and aerosols.

  10. IGS Clock Products for Accurate Geodetic and Timing Applications

    NASA Astrophysics Data System (ADS)

    Senior, K. L.; Ray, J. R.

    2007-12-01

    The performance of any GNSS is intimately related to the characteristics of the satellite clocks, so an understanding of the clock behavior is vital. The accurate products of the IGS enable daily point positions to the sub-cm level and continuous global clock comparisons to the sub-ns level. Time transfers are less accurate than associated positioning because of: 1) difficult-to-measure hardware delays; 2) the limiting pseudorange measurement errors. Both factors arise from characteristics of the pseudorange signals, which are easily degraded by multipath and other effects. The behavior of the satellite clocks are also be important. Over sub-daily intervals, IGS products show that approximate power-law stochastic processes govern all GPS clocks. The Block IIA Rb and Cs clocks obey random walk noise, with the Rb clocks up to nearly an order of magnitude more stable. Due to the high-frequency noise of the onboard Time Keeping system in the newer Block IIR and IIR-M satellites, their Rb clocks are dominantly white noise up to a few 1000 s with standard deviations of 90 to 180 ps. Superposed on this random background, periodic signals are present at four harmonic frequencies, n × (2.0029 ± 0.0005) cycles per day for n = 1, 2, 3, and 4. The equivalent fundamental period is 11.9826 hours, which surprisingly differs from the reported mean GPS orbital period of 11.9659 hours by 60 ± 11 s. We cannot account for this apparent discrepancy but note that a clear relationship between the periodic signals and the orbital dynamics is evidenced for some satellites by modulations of the spectral amplitudes with eclipse season. The Cs clocks are more strongly affected than the Rb clocks. All four harmonics are much smaller for the IIR/IIR-M satellites than for the older blocks. The strong 12- and 6-hour periodics in most GPS clocks dictate that these variations should be modeled in all high-accuracy applications, such as for timescale formation, interpolation of IGS clock products

  11. Research on the Rapid and Accurate Positioning and Orientation Approach for Land Missile-Launching Vehicle

    PubMed Central

    Li, Kui; Wang, Lei; Lv, Yanhong; Gao, Pengyu; Song, Tianxiao

    2015-01-01

    Getting a land vehicle’s accurate position, azimuth and attitude rapidly is significant for vehicle based weapons’ combat effectiveness. In this paper, a new approach to acquire vehicle’s accurate position and orientation is proposed. It uses biaxial optical detection platform (BODP) to aim at and lock in no less than three pre-set cooperative targets, whose accurate positions are measured beforehand. Then, it calculates the vehicle’s accurate position, azimuth and attitudes by the rough position and orientation provided by vehicle based navigation systems and no less than three couples of azimuth and pitch angles measured by BODP. The proposed approach does not depend on Global Navigation Satellite System (GNSS), thus it is autonomous and difficult to interfere. Meanwhile, it only needs a rough position and orientation as algorithm’s iterative initial value, consequently, it does not have high performance requirement for Inertial Navigation System (INS), odometer and other vehicle based navigation systems, even in high precise applications. This paper described the system’s working procedure, presented theoretical deviation of the algorithm, and then verified its effectiveness through simulation and vehicle experiments. The simulation and experimental results indicate that the proposed approach can achieve positioning and orientation accuracy of 0.2 m and 20″ respectively in less than 3 min. PMID:26492249

  12. Research on the rapid and accurate positioning and orientation approach for land missile-launching vehicle.

    PubMed

    Li, Kui; Wang, Lei; Lv, Yanhong; Gao, Pengyu; Song, Tianxiao

    2015-01-01

    Getting a land vehicle's accurate position, azimuth and attitude rapidly is significant for vehicle based weapons' combat effectiveness. In this paper, a new approach to acquire vehicle's accurate position and orientation is proposed. It uses biaxial optical detection platform (BODP) to aim at and lock in no less than three pre-set cooperative targets, whose accurate positions are measured beforehand. Then, it calculates the vehicle's accurate position, azimuth and attitudes by the rough position and orientation provided by vehicle based navigation systems and no less than three couples of azimuth and pitch angles measured by BODP. The proposed approach does not depend on Global Navigation Satellite System (GNSS), thus it is autonomous and difficult to interfere. Meanwhile, it only needs a rough position and orientation as algorithm's iterative initial value, consequently, it does not have high performance requirement for Inertial Navigation System (INS), odometer and other vehicle based navigation systems, even in high precise applications. This paper described the system's working procedure, presented theoretical deviation of the algorithm, and then verified its effectiveness through simulation and vehicle experiments. The simulation and experimental results indicate that the proposed approach can achieve positioning and orientation accuracy of 0.2 m and 20″ respectively in less than 3 min. PMID:26492249

  13. 78 FR 34604 - Submitting Complete and Accurate Information

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-10

    ... COMMISSION 10 CFR Part 50 Submitting Complete and Accurate Information AGENCY: Nuclear Regulatory Commission... accurate information as would a licensee or an applicant for a license.'' DATES: Submit comments by August... may submit comments by any of the following methods (unless this document describes a different...

  14. Tube dimpling tool assures accurate dip-brazed joints

    NASA Technical Reports Server (NTRS)

    Beuyukian, C. S.; Heisman, R. M.

    1968-01-01

    Portable, hand-held dimpling tool assures accurate brazed joints between tubes of different diameters. Prior to brazing, the tool performs precise dimpling and nipple forming and also provides control and accurate measuring of the height of nipples and depth of dimples so formed.

  15. 31 CFR 205.24 - How are accurate estimates maintained?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false How are accurate estimates maintained... Treasury-State Agreement § 205.24 How are accurate estimates maintained? (a) If a State has knowledge that an estimate does not reasonably correspond to the State's cash needs for a Federal assistance...

  16. A parallel high-order accurate finite element nonlinear Stokes ice sheet model and benchmark experiments

    SciTech Connect

    Leng, Wei; Ju, Lili; Gunzburger, Max; Price, Stephen; Ringler, Todd

    2012-01-01

    The numerical modeling of glacier and ice sheet evolution is a subject of growing interest, in part because of the potential for models to inform estimates of global sea level change. This paper focuses on the development of a numerical model that determines the velocity and pressure fields within an ice sheet. Our numerical model features a high-fidelity mathematical model involving the nonlinear Stokes system and combinations of no-sliding and sliding basal boundary conditions, high-order accurate finite element discretizations based on variable resolution grids, and highly scalable parallel solution strategies, all of which contribute to a numerical model that can achieve accurate velocity and pressure approximations in a highly efficient manner. We demonstrate the accuracy and efficiency of our model by analytical solution tests, established ice sheet benchmark experiments, and comparisons with other well-established ice sheet models.

  17. Accurate body composition measures from whole-body silhouettes

    PubMed Central

    Xie, Bowen; Avila, Jesus I.; Ng, Bennett K.; Fan, Bo; Loo, Victoria; Gilsanz, Vicente; Hangartner, Thomas; Kalkwarf, Heidi J.; Lappe, Joan; Oberfield, Sharon; Winer, Karen; Zemel, Babette; Shepherd, John A.

    2015-01-01

    Purpose: Obesity and its consequences, such as diabetes, are global health issues that burden about 171 × 106 adult individuals worldwide. Fat mass index (FMI, kg/m2), fat-free mass index (FFMI, kg/m2), and percent fat mass may be useful to evaluate under- and overnutrition and muscle development in a clinical or research environment. This proof-of-concept study tested whether frontal whole-body silhouettes could be used to accurately measure body composition parameters using active shape modeling (ASM) techniques. Methods: Binary shape images (silhouettes) were generated from the skin outline of dual-energy x-ray absorptiometry (DXA) whole-body scans of 200 healthy children of ages from 6 to 16 yr. The silhouette shape variation from the average was described using an ASM, which computed principal components for unique modes of shape. Predictive models were derived from the modes for FMI, FFMI, and percent fat using stepwise linear regression. The models were compared to simple models using demographics alone [age, sex, height, weight, and body mass index z-scores (BMIZ)]. Results: The authors found that 95% of the shape variation of the sampled population could be explained using 26 modes. In most cases, the body composition variables could be predicted similarly between demographics-only and shape-only models. However, the combination of shape with demographics improved all estimates of boys and girls compared to the demographics-only model. The best prediction models for FMI, FFMI, and percent fat agreed with the actual measures with R2 adj. (the coefficient of determination adjusted for the number of parameters used in the model equation) values of 0.86, 0.95, and 0.75 for boys and 0.90, 0.89, and 0.69 for girls, respectively. Conclusions: Whole-body silhouettes in children may be useful to derive estimates of body composition including FMI, FFMI, and percent fat. These results support the feasibility of measuring body composition variables from simple

  18. Technological Basis and Scientific Returns for Absolutely Accurate Measurements

    NASA Astrophysics Data System (ADS)

    Dykema, J. A.; Anderson, J.

    2011-12-01

    The 2006 NRC Decadal Survey fostered a new appreciation for societal objectives as a driving motivation for Earth science. Many high-priority societal objectives are dependent on predictions of weather and climate. These predictions are based on numerical models, which derive from approximate representations of well-founded physics and chemistry on space and timescales appropriate to global and regional prediction. These laws of chemistry and physics in turn have a well-defined quantitative relationship with physical measurement units, provided these measurement units are linked to international measurement standards that are the foundation of contemporary measurement science and standards for engineering and commerce. Without this linkage, measurements have an ambiguous relationship to scientific principles that introduces avoidable uncertainty in analyses, predictions, and improved understanding of the Earth system. Since the improvement of climate and weather prediction is fundamentally dependent on the improvement of the representation of physical processes, measurement systems that reduce the ambiguity between physical truth and observations represent an essential component of a national strategy for understanding and living with the Earth system. This paper examines the technological basis and potential science returns of sensors that make measurements that are quantitatively tied on-orbit to international measurement standards, and thus testable to systematic errors. This measurement strategy provides several distinct benefits. First, because of the quantitative relationship between these international measurement standards and fundamental physical constants, measurements of this type accurately capture the true physical and chemical behavior of the climate system and are not subject to adjustment due to excluded measurement physics or instrumental artifacts. In addition, such measurements can be reproduced by scientists anywhere in the world, at any time

  19. [The determinant role of an accurate medicosocial approach in the prognosis of pediatric blood diseases].

    PubMed

    Toppet, M

    2005-01-01

    The care of infancy and childhood blood diseases implies a comprehensive medicosocial approach. This is a prerequisite for regular follow-up, for satisfactory compliance to treatment and for optimal patient's quality of life. Different modalities of medicosocial approach have been developed in the pediatric department (firstly in the Hospital Saint Pierre and than in the Children's University Hospital HUDERF). The drastic importance of a recent reform of the increased family allowances is briefly presented. The author underlines the determinant role of an accurate global approach, in which the patient and the family are surrounded by a multidisciplinary team, including social workers. PMID:16454232

  20. Dengue: a continuing global threat

    PubMed Central

    Guzman, Maria G.; Halstead, Scott B.; Artsob, Harvey; Buchy, Philippe; Farrar, Jeremy; Gubler, Duane J.; Hunsperger, Elizabeth; Kroeger, Axel; Margolis, Harold S.; Martínez, Eric; Nathan, Michael B.; Pelegrino, Jose Luis; Simmons, Cameron; Yoksan, Sutee; Peeling, Rosanna W.

    2014-01-01

    Dengue fever and dengue haemorrhagic fever are important arthropod-borne viral diseases. Each year, there are ~50 million dengue infections and ~500,000 individuals are hospitalized with dengue haemorrhagic fever, mainly in Southeast Asia, the Pacific and the Americas. Illness is produced by any of the four dengue virus serotypes. A global strategy aimed at increasing the capacity for surveillance and outbreak response, changing behaviours and reducing the disease burden using integrated vector management in conjunction with early and accurate diagnosis has been advocated. Antiviral drugs and vaccines that are currently under development could also make an important contribution to dengue control in the future. PMID:21079655

  1. Screened exchange hybrid density functional for accurate and efficient structures and interaction energies.

    PubMed

    Brandenburg, Jan Gerit; Caldeweyher, Eike; Grimme, Stefan

    2016-06-21

    We extend the recently introduced PBEh-3c global hybrid density functional [S. Grimme et al., J. Chem. Phys., 2015, 143, 054107] by a screened Fock exchange variant based on the Henderson-Janesko-Scuseria exchange hole model. While the excellent performance of the global hybrid is maintained for small covalently bound molecules, its performance for computed condensed phase mass densities is further improved. Most importantly, a speed up of 30 to 50% can be achieved and especially for small orbital energy gap cases, the method is numerically much more robust. The latter point is important for many applications, e.g., for metal-organic frameworks, organic semiconductors, or protein structures. This enables an accurate density functional based electronic structure calculation of a full DNA helix structure on a single core desktop computer which is presented as an example in addition to comprehensive benchmark results. PMID:27240749

  2. A new global ionospheric model

    NASA Technical Reports Server (NTRS)

    Yip, K. W.; Vonroos, O. H.

    1975-01-01

    A new global ionospheric model was successfully implemented. The daytime portion of this model provides one-way ionospheric range corrections that compare favorably with those derived from the Mariner Venus/Mercury S- and X-band dual frequency Doppler data. For elevation angles, gamma higher than 30 deg and solar zenith angle less than 80 deg, this model provides calibrations accurate to a few centimeters. The calibrations provided by the nighttime model are also very reasonable. It is interesting to note that the daytime ionospheric calibrations derived from the current calibration scheme, DIEN/TIEN, are fairly close to those given by the new global model, especially in the temporal variations and thus the Doppler effects. The comparison between the nighttime model and DIEN/TIEN was based on the one-way ionospheric range corrections for three passes near the Mariner 9 encounter with Mars in 1971. They can differ by over 30%.

  3. On computational schemes for global-local stress analysis

    NASA Technical Reports Server (NTRS)

    Reddy, J. N.

    1989-01-01

    An overview is given of global-local stress analysis methods and associated difficulties and recommendations for future research. The phrase global-local analysis is understood to be an analysis in which some parts of the domain or structure are identified, for reasons of accurate determination of stresses and displacements or for more refined analysis than in the remaining parts. The parts of refined analysis are termed local and the remaining parts are called global. Typically local regions are small in size compared to global regions, while the computational effort can be larger in local regions than in global regions.

  4. Improving Global Models of Remotely Sensed Ocean Chlorophyll Content Using Partial Least Squares and Geographically Weighted Regression

    NASA Astrophysics Data System (ADS)

    Gholizadeh, H.; Robeson, S. M.

    2015-12-01

    Empirical models have been widely used to estimate global chlorophyll content from remotely sensed data. Here, we focus on the standard NASA empirical models that use blue-green band ratios. These band ratio ocean color (OC) algorithms are in the form of fourth-order polynomials and the parameters of these polynomials (i.e. coefficients) are estimated from the NASA bio-Optical Marine Algorithm Data set (NOMAD). Most of the points in this data set have been sampled from tropical and temperate regions. However, polynomial coefficients obtained from this data set are used to estimate chlorophyll content in all ocean regions with different properties such as sea-surface temperature, salinity, and downwelling/upwelling patterns. Further, the polynomial terms in these models are highly correlated. In sum, the limitations of these empirical models are as follows: 1) the independent variables within the empirical models, in their current form, are correlated (multicollinear), and 2) current algorithms are global approaches and are based on the spatial stationarity assumption, so they are independent of location. Multicollinearity problem is resolved by using partial least squares (PLS). PLS, which transforms the data into a set of independent components, can be considered as a combined form of principal component regression (PCR) and multiple regression. Geographically weighted regression (GWR) is also used to investigate the validity of spatial stationarity assumption. GWR solves a regression model over each sample point by using the observations within its neighbourhood. PLS results show that the empirical method underestimates chlorophyll content in high latitudes, including the Southern Ocean region, when compared to PLS (see Figure 1). Cluster analysis of GWR coefficients also shows that the spatial stationarity assumption in empirical models is not likely a valid assumption.

  5. Accurate calculation of diffraction-limited encircled and ensquared energy.

    PubMed

    Andersen, Torben B

    2015-09-01

    Mathematical properties of the encircled and ensquared energy functions for the diffraction-limited point-spread function (PSF) are presented. These include power series and a set of linear differential equations that facilitate the accurate calculation of these functions. Asymptotic expressions are derived that provide very accurate estimates for the relative amount of energy in the diffraction PSF that fall outside a square or rectangular large detector. Tables with accurate values of the encircled and ensquared energy functions are also presented. PMID:26368873

  6. Rapid Geometric Correction of SSC Terrasar-X Images with Direct Georeferencing, Global dem and Global Geoid Models

    NASA Astrophysics Data System (ADS)

    Vassilaki, D. I.; Stamos, A. A.; Ioannidis, C.

    2013-05-01

    In this paper a process for rapid geometric correction of slant range SAR images is presented. The process is completely independent of ground control information thanks to the direct georeferencing method capabilities offered by the TerraSAR-X sensor. The process is especially rapid due to the use of readily available global DEMs and global geoid models. An additional advantage of this process is its flexibility. If a more accurate local DEM or local geoid model is readily available it can be used instead of the global DEM or global geoid model. The process is applied to geometrically correct a SSC TerraSAR-X image over a sub-urban mountainous area using the SRTM and the ASTER global DEMs and the EGM2008 global geoid model. Additionally two local, more accurate DEMs, are used. The accuracy of the process is evaluated by independent check points.

  7. Global mean sea surface based upon SEASAT altimeter data

    NASA Technical Reports Server (NTRS)

    Marsh, J. G.

    1984-01-01

    A global mean sea surface based upon the SEASAT altimeter data was derived. A combination of crossing arc techniques, accurate SEASAT reference orbits, and a previously computed GOES-3/SEASAT mean sea surface were used in the computation process. This mean sea surface provides a basis for the determination of global ocean circulation patterns and for detailed analysis of the Earth's internal structure. A contour map of the global mean sea surface is presented.

  8. Underworld Goes Global

    NASA Astrophysics Data System (ADS)

    Giordani, J. P.; Moresi, L. N.; capitanio, F. A.; Mansour, J.; Quenette, S. D.

    2012-12-01

    We recently embarked on a project to develop a spherical version of the Underworld code. It seemed fitting that we should try to complete this monstrous journey in under 80 days and with little more than a carpet bag containing a few clean clothes and a book of finite element methodology to guide the way. We report our adventures along the way. Underworld was designed to model processes at the lithosphere scale and was therefore focused on efficient/accurate treatment of large deformation, history dependent material properties and interfaces. At the scale of interest, the curvature of the Earth can often be neglected and the original Underworld code assumed, for simplicity, a Cartesian geometry. Two important considerations led us to develop a spherical code: 1) that many of the processes of interest at the lithospheric scale are driven by global-scale flows which we are increasingly incorporating directly in models (e.g. convergent boundary processes driven by the buoyancy of subducted slabs); and 2) that mapping observables from {lat, long, depth} to Cartesian coordinates introduces an unnecessary complication to interpretation of the resulting models. (Actuallly, three important considerations ... having flown around the world a number of times, keenly observing the world below, and having failed to observe any vertices or edges ... ) We will discuss our choices in mesh construction, particle advection, integration schemes, parallel decomposition, and the abstractions necessary to keep the underlying code independent of the chosen geometry.

  9. Accurate Alignment of Plasma Channels Based on Laser Centroid Oscillations

    SciTech Connect

    Gonsalves, Anthony; Nakamura, Kei; Lin, Chen; Osterhoff, Jens; Shiraishi, Satomi; Schroeder, Carl; Geddes, Cameron; Toth, Csaba; Esarey, Eric; Leemans, Wim

    2011-03-23

    A technique has been developed to accurately align a laser beam through a plasma channel by minimizing the shift in laser centroid and angle at the channel outptut. If only the shift in centroid or angle is measured, then accurate alignment is provided by minimizing laser centroid motion at the channel exit as the channel properties are scanned. The improvement in alignment accuracy provided by this technique is important for minimizing electron beam pointing errors in laser plasma accelerators.

  10. Accurate wavelength calibration method for flat-field grating spectrometers.

    PubMed

    Du, Xuewei; Li, Chaoyang; Xu, Zhe; Wang, Qiuping

    2011-09-01

    A portable spectrometer prototype is built to study wavelength calibration for flat-field grating spectrometers. An accurate calibration method called parameter fitting is presented. Both optical and structural parameters of the spectrometer are included in the wavelength calibration model, which accurately describes the relationship between wavelength and pixel position. Along with higher calibration accuracy, the proposed calibration method can provide information about errors in the installation of the optical components, which will be helpful for spectrometer alignment. PMID:21929865

  11. The Use of Accurate Mass Tags for High-Throughput Microbial Proteomics

    SciTech Connect

    Smith, Richard D. ); Anderson, Gordon A. ); Lipton, Mary S. ); Masselon, Christophe D. ); Pasa Tolic, Ljiljana ); Shen, Yufeng ); Udseth, Harold R. )

    2002-08-01

    We describe and demonstrate a global strategy that extends the sensitivity, dynamic range, comprehensiveness, and throughput of proteomic measurements based upon the use of peptide accurate mass tags (AMTs) produced by global protein enzymatic digestion. The two-stage strategy exploits Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometry to validate peptide AMTs for a specific organism, tissue or cell type from potential mass tags identified using conventional tandem mass spectrometry (MS/MS) methods, providing greater confidence in identifications as well as the basis for subsequent measurements without the need for MS/MS, and thus with greater sensitivity and increased throughput. A single high resolution capillary liquid chromatography separation combined with high sensitivity, high resolution and ac-curate FT-ICR measurements has been shown capable of characterizing peptide mixtures of significantly more than 10 5 components with mass accuracies of -1 ppm, sufficient for broad protein identification using AMTs. Other attractions of the approach include the broad and relatively unbiased proteome coverage, the capability for exploiting stable isotope labeling methods to realize high precision for relative protein abundance measurements, and the projected potential for study of mammalian proteomes when combined with additional sample fractionation. Using this strategy, in our first application we have been able to identify AMTs for 60% of the potentially expressed proteins in the organism Deinococcus radiodurans.

  12. Global Carbon Budget 2015

    DOE PAGESBeta

    Le Quéré, C.; Moriarty, R.; Andrew, R. M.; Canadell, J. G.; Sitch, S.; Korsbakken, J. I.; Friedlingstein, P.; Peters, G. P.; Andres, R. J.; Boden, T. A.; et al

    2015-12-07

    Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics, and model estimates and their interpretation by a broad scientific community. We also discuss changes compared to previous estimates as well as consistency within and among components, alongside methodology andmore » data limitations. CO2 emissions from fossil fuels and industry (EFF) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover-change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. Moreover, the mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO2, and land-cover change (some including nitrogen–carbon interactions). We compare the mean land and ocean fluxes and their variability to estimates from three atmospheric inverse methods for three broad latitude bands. All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each

  13. Global Carbon Budget 2015

    SciTech Connect

    Le Quéré, C.; Moriarty, R.; Andrew, R. M.; Canadell, J. G.; Sitch, S.; Korsbakken, J. I.; Friedlingstein, P.; Peters, G. P.; Andres, R. J.; Boden, T. A.; Houghton, R. A.; House, J. I.; Keeling, R. F.; Tans, P.; Arneth, A.; Bakker, D. C. E.; Barbero, L.; Bopp, L.; Chang, J.; Chevallier, F.; Chini, L. P.; Ciais, P.; Fader, M.; Gkritzalis, T.; Harris, I.; Hauck, J.; Ilyina, T.; Jain, A. K.; Kato, E.; Kitidis, V.; Klein Goldewijk, K.; Landschützer, P.; Lauvset, S. K.; Lefèvre, N.; Lenton, A.; Lima, I. D.; Metzl, N.; Millero, F.; Munro, D. R.; Murata, A.; Nabel, J. E. M. S.; Nakaoka, S.; Nojiri, Y.; O'Brien, K.; Olsen, A.; Ono, T.; Pérez, F. F.; Pfeil, B.; Pierrot, D.; Poulter, B.; Rehder, G.; Rödenbeck, C.; Saito, S.; Schuster, U.; Schwinger, J.; Séférian, R.; Steinhoff, T.; Stocker, B. D.; Sutton, A. J.; Takahashi, T.; Tilbrook, B.; van der Laan-Luijkx, I. T.; van der Werf, G. R.; van Heuven, S.; Vandemark, D.; Viovy, N.; Wiltshire, A.; Zaehle, S.; Zeng, N.

    2015-12-07

    Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics, and model estimates and their interpretation by a broad scientific community. We also discuss changes compared to previous estimates as well as consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil fuels and industry (EFF) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover-change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. Moreover, the mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO2, and land-cover change (some including nitrogen–carbon interactions). We compare the mean land and ocean fluxes and their variability to estimates from three

  14. Global carbon budget 2014

    DOE PAGESBeta

    Le Quéré, C.; Moriarty, R.; Andrew, R. M.; Peters, G. P.; Ciais, P.; Friedlingstein, P.; Jones, S. D.; Sitch, S.; Tans, P.; Arneth, A.; et al

    2015-05-08

    Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics, and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates, consistency within and among components, alongside methodology and data limitations. CO2 emissionsmore » from fossil fuel combustion and cement production (EFF) are based on energy statistics and cement production data, respectively, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover-change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO2, and land-cover-change (some including nitrogen–carbon interactions). We compare the mean land and ocean fluxes and their variability to estimates from three atmospheric inverse methods for three broad latitude bands. All uncertainties are reported as ±1σ;, reflecting the current capacity to characterise the annual estimates

  15. Global Carbon Budget 2015

    NASA Astrophysics Data System (ADS)

    Le Quéré, C.; Moriarty, R.; Andrew, R. M.; Canadell, J. G.; Sitch, S.; Korsbakken, J. I.; Friedlingstein, P.; Peters, G. P.; Andres, R. J.; Boden, T. A.; Houghton, R. A.; House, J. I.; Keeling, R. F.; Tans, P.; Arneth, A.; Bakker, D. C. E.; Barbero, L.; Bopp, L.; Chang, J.; Chevallier, F.; Chini, L. P.; Ciais, P.; Fader, M.; Feely, R. A.; Gkritzalis, T.; Harris, I.; Hauck, J.; Ilyina, T.; Jain, A. K.; Kato, E.; Kitidis, V.; Klein Goldewijk, K.; Koven, C.; Landschützer, P.; Lauvset, S. K.; Lefèvre, N.; Lenton, A.; Lima, I. D.; Metzl, N.; Millero, F.; Munro, D. R.; Murata, A.; Nabel, J. E. M. S.; Nakaoka, S.; Nojiri, Y.; O'Brien, K.; Olsen, A.; Ono, T.; Pérez, F. F.; Pfeil, B.; Pierrot, D.; Poulter, B.; Rehder, G.; Rödenbeck, C.; Saito, S.; Schuster, U.; Schwinger, J.; Séférian, R.; Steinhoff, T.; Stocker, B. D.; Sutton, A. J.; Takahashi, T.; Tilbrook, B.; van der Laan-Luijkx, I. T.; van der Werf, G. R.; van Heuven, S.; Vandemark, D.; Viovy, N.; Wiltshire, A.; Zaehle, S.; Zeng, N.

    2015-12-01

    Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics, and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates as well as consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil fuels and industry (EFF) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover-change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO2, and land-cover change (some including nitrogen-carbon interactions). We compare the mean land and ocean fluxes and their variability to estimates from three atmospheric inverse methods for three broad latitude bands. All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each component of the global

  16. Global carbon budget 2014

    NASA Astrophysics Data System (ADS)

    Le Quéré, C.; Moriarty, R.; Andrew, R. M.; Peters, G. P.; Ciais, P.; Friedlingstein, P.; Jones, S. D.; Sitch, S.; Tans, P.; Arneth, A.; Boden, T. A.; Bopp, L.; Bozec, Y.; Canadell, J. G.; Chini, L. P.; Chevallier, F.; Cosca, C. E.; Harris, I.; Hoppema, M.; Houghton, R. A.; House, J. I.; Jain, A. K.; Johannessen, T.; Kato, E.; Keeling, R. F.; Kitidis, V.; Klein Goldewijk, K.; Koven, C.; Landa, C. S.; Landschützer, P.; Lenton, A.; Lima, I. D.; Marland, G.; Mathis, J. T.; Metzl, N.; Nojiri, Y.; Olsen, A.; Ono, T.; Peng, S.; Peters, W.; Pfeil, B.; Poulter, B.; Raupach, M. R.; Regnier, P.; Rödenbeck, C.; Saito, S.; Salisbury, J. E.; Schuster, U.; Schwinger, J.; Séférian, R.; Segschneider, J.; Steinhoff, T.; Stocker, B. D.; Sutton, A. J.; Takahashi, T.; Tilbrook, B.; van der Werf, G. R.; Viovy, N.; Wang, Y.-P.; Wanninkhof, R.; Wiltshire, A.; Zeng, N.

    2015-05-01

    Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics, and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates, consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil fuel combustion and cement production (EFF) are based on energy statistics and cement production data, respectively, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover-change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO2, and land-cover-change (some including nitrogen-carbon interactions). We compare the mean land and ocean fluxes and their variability to estimates from three atmospheric inverse methods for three broad latitude bands. All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each

  17. Global carbon budget 2014

    SciTech Connect

    Le Quéré, C.; Moriarty, R.; Andrew, R. M.; Peters, G. P.; Ciais, P.; Friedlingstein, P.; Jones, S. D.; Sitch, S.; Tans, P.; Arneth, A.; Boden, T. A.; Bopp, L.; Bozec, Y.; Canadell, J. G.; Chini, L. P.; Chevallier, F.; Cosca, C. E.; Harris, I.; Hoppema, M.; Houghton, R. A.; House, J. I.; Jain, A. K.; Johannessen, T.; Kato, E.; Keeling, R. F.; Kitidis, V.; Klein Goldewijk, K.; Koven, C.; Landa, C. S.; Landschützer, P.; Lenton, A.; Lima, I. D.; Marland, G.; Mathis, J. T.; Metzl, N.; Nojiri, Y.; Olsen, A.; Ono, T.; Peng, S.; Peters, W.; Pfeil, B.; Poulter, B.; Raupach, M. R.; Regnier, P.; Rödenbeck, C.; Saito, S.; Salisbury, J. E.; Schuster, U.; Schwinger, J.; Séférian, R.; Segschneider, J.; Steinhoff, T.; Stocker, B. D.; Sutton, A. J.; Takahashi, T.; Tilbrook, B.; van der Werf, G. R.; Viovy, N.; Wang, Y.-P.; Wanninkhof, R.; Wiltshire, A.; Zeng, N.

    2015-05-08

    Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics, and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates, consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil fuel combustion and cement production (EFF) are based on energy statistics and cement production data, respectively, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover-change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO2, and land-cover-change (some including nitrogen–carbon interactions). We compare the mean land and ocean fluxes and their variability to estimates from

  18. High Order Schemes in Bats-R-US for Faster and More Accurate Predictions

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Toth, G.; Gombosi, T. I.

    2014-12-01

    BATS-R-US is a widely used global magnetohydrodynamics model that originally employed second order accurate TVD schemes combined with block based Adaptive Mesh Refinement (AMR) to achieve high resolution in the regions of interest. In the last years we have implemented fifth order accurate finite difference schemes CWENO5 and MP5 for uniform Cartesian grids. Now the high order schemes have been extended to generalized coordinates, including spherical grids and also to the non-uniform AMR grids including dynamic regridding. We present numerical tests that verify the preservation of free-stream solution and high-order accuracy as well as robust oscillation-free behavior near discontinuities. We apply the new high order accurate schemes to both heliospheric and magnetospheric simulations and show that it is robust and can achieve the same accuracy as the second order scheme with much less computational resources. This is especially important for space weather prediction that requires faster than real time code execution.

  19. Can phenological models predict tree phenology accurately under climate change conditions?

    NASA Astrophysics Data System (ADS)

    Chuine, Isabelle; Bonhomme, Marc; Legave, Jean Michel; García de Cortázar-Atauri, Inaki; Charrier, Guillaume; Lacointe, André; Améglio, Thierry

    2014-05-01

    The onset of the growing season of trees has been globally earlier by 2.3 days/decade during the last 50 years because of global warming and this trend is predicted to continue according to climate forecast. The effect of temperature on plant phenology is however not linear because temperature has a dual effect on bud development. On one hand, low temperatures are necessary to break bud dormancy, and on the other hand higher temperatures are necessary to promote bud cells growth afterwards. Increasing phenological changes in temperate woody species have strong impacts on forest trees distribution and productivity, as well as crops cultivation areas. Accurate predictions of trees phenology are therefore a prerequisite to understand and foresee the impacts of climate change on forests and agrosystems. Different process-based models have been developed in the last two decades to predict the date of budburst or flowering of woody species. They are two main families: (1) one-phase models which consider only the ecodormancy phase and make the assumption that endodormancy is always broken before adequate climatic conditions for cell growth occur; and (2) two-phase models which consider both the endodormancy and ecodormancy phases and predict a date of dormancy break which varies from year to year. So far, one-phase models have been able to predict accurately tree bud break and flowering under historical climate. However, because they do not consider what happens prior to ecodormancy, and especially the possible negative effect of winter temperature warming on dormancy break, it seems unlikely that they can provide accurate predictions in future climate conditions. It is indeed well known that a lack of low temperature results in abnormal pattern of bud break and development in temperate fruit trees. An accurate modelling of the dormancy break date has thus become a major issue in phenology modelling. Two-phases phenological models predict that global warming should delay

  20. Web Map Services (WMS) Global Mosaic

    NASA Technical Reports Server (NTRS)

    Percivall, George; Plesea, Lucian

    2003-01-01

    The WMS Global Mosaic provides access to imagery of the global landmass using an open standard for web mapping. The seamless image is a mosaic of Landsat 7 scenes; geographically-accurate with 30 and 15 meter resolutions. By using the OpenGIS Web Map Service (WMS) interface, any organization can use the global mosaic as a layer in their geospatial applications. Based on a trade study, an implementation approach was chosen that extends a previously developed WMS hosting a Landsat 5 CONUS mosaic developed by JPL. The WMS Global Mosaic supports the NASA Geospatial Interoperability Office goal of providing an integrated digital representation of the Earth, widely accessible for humanity's critical decisions.

  1. Can phenological models predict tree phenology accurately in the future? The unrevealed hurdle of endodormancy break.

    PubMed

    Chuine, Isabelle; Bonhomme, Marc; Legave, Jean-Michel; García de Cortázar-Atauri, Iñaki; Charrier, Guillaume; Lacointe, André; Améglio, Thierry

    2016-10-01

    The onset of the growing season of trees has been earlier by 2.3 days per decade during the last 40 years in temperate Europe because of global warming. The effect of temperature on plant phenology is, however, not linear because temperature has a dual effect on bud development. On one hand, low temperatures are necessary to break bud endodormancy, and, on the other hand, higher temperatures are necessary to promote bud cell growth afterward. Different process-based models have been developed in the last decades to predict the date of budbreak of woody species. They predict that global warming should delay or compromise endodormancy break at the species equatorward range limits leading to a delay or even impossibility to flower or set new leaves. These models are classically parameterized with flowering or budbreak dates only, with no information on the endodormancy break date because this information is very scarce. Here, we evaluated the efficiency of a set of phenological models to accurately predict the endodormancy break dates of three fruit trees. Our results show that models calibrated solely with budbreak dates usually do not accurately predict the endodormancy break date. Providing endodormancy break date for the model parameterization results in much more accurate prediction of this latter, with, however, a higher error than that on budbreak dates. Most importantly, we show that models not calibrated with endodormancy break dates can generate large discrepancies in forecasted budbreak dates when using climate scenarios as compared to models calibrated with endodormancy break dates. This discrepancy increases with mean annual temperature and is therefore the strongest after 2050 in the southernmost regions. Our results claim for the urgent need of massive measurements of endodormancy break dates in forest and fruit trees to yield more robust projections of phenological changes in a near future. PMID:27272707

  2. Nonexposure accurate location K-anonymity algorithm in LBS.

    PubMed

    Jia, Jinying; Zhang, Fengli

    2014-01-01

    This paper tackles location privacy protection in current location-based services (LBS) where mobile users have to report their exact location information to an LBS provider in order to obtain their desired services. Location cloaking has been proposed and well studied to protect user privacy. It blurs the user's accurate coordinate and replaces it with a well-shaped cloaked region. However, to obtain such an anonymous spatial region (ASR), nearly all existent cloaking algorithms require knowing the accurate locations of all users. Therefore, location cloaking without exposing the user's accurate location to any party is urgently needed. In this paper, we present such two nonexposure accurate location cloaking algorithms. They are designed for K-anonymity, and cloaking is performed based on the identifications (IDs) of the grid areas which were reported by all the users, instead of directly on their accurate coordinates. Experimental results show that our algorithms are more secure than the existent cloaking algorithms, need not have all the users reporting their locations all the time, and can generate smaller ASR. PMID:24605060

  3. Nonexposure Accurate Location K-Anonymity Algorithm in LBS

    PubMed Central

    2014-01-01

    This paper tackles location privacy protection in current location-based services (LBS) where mobile users have to report their exact location information to an LBS provider in order to obtain their desired services. Location cloaking has been proposed and well studied to protect user privacy. It blurs the user's accurate coordinate and replaces it with a well-shaped cloaked region. However, to obtain such an anonymous spatial region (ASR), nearly all existent cloaking algorithms require knowing the accurate locations of all users. Therefore, location cloaking without exposing the user's accurate location to any party is urgently needed. In this paper, we present such two nonexposure accurate location cloaking algorithms. They are designed for K-anonymity, and cloaking is performed based on the identifications (IDs) of the grid areas which were reported by all the users, instead of directly on their accurate coordinates. Experimental results show that our algorithms are more secure than the existent cloaking algorithms, need not have all the users reporting their locations all the time, and can generate smaller ASR. PMID:24605060

  4. An Attainable Global Perspective.

    ERIC Educational Resources Information Center

    de Castaneda, Viann Pedersen

    Concordia College (Minnesota) has established a global studies curriculum that encourages the development of a global perspective in future business leaders. Global perspective is seen as having five dimensions: (1) perspective consciousness; (2) "state of the planet" awareness; (3) cross-cultural awareness; (4) knowledge of global dynamics; and…

  5. Global carbon budget 2013

    NASA Astrophysics Data System (ADS)

    Le Quéré, C.; Peters, G. P.; Andres, R. J.; Andrew, R. M.; Boden, T. A.; Ciais, P.; Friedlingstein, P.; Houghton, R. A.; Marland, G.; Moriarty, R.; Sitch, S.; Tans, P.; Arneth, A.; Arvanitis, A.; Bakker, D. C. E.; Bopp, L.; Canadell, J. G.; Chini, L. P.; Doney, S. C.; Harper, A.; Harris, I.; House, J. I.; Jain, A. K.; Jones, S. D.; Kato, E.; Keeling, R. F.; Klein Goldewijk, K.; Körtzinger, A.; Koven, C.; Lefèvre, N.; Maignan, F.; Omar, A.; Ono, T.; Park, G.-H.; Pfeil, B.; Poulter, B.; Raupach, M. R.; Regnier, P.; Rödenbeck, C.; Saito, S.; Schwinger, J.; Segschneider, J.; Stocker, B. D.; Takahashi, T.; Tilbrook, B.; van Heuven, S.; Viovy, N.; Wanninkhof, R.; Wiltshire, A.; Zaehle, S.

    2014-06-01

    Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates, consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil-fuel combustion and cement production (EFF) are based on energy statistics, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated for the first time in this budget with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO2 and land cover change (some including nitrogen-carbon interactions). All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each component of the global carbon budget. For the last decade available (2003-2012), EFF was 8.6 ± 0.4 GtC yr-1, ELUC 0.9 ± 0.5 GtC yr-1, GATM 4.3 ± 0.1 GtC yr-1

  6. Global carbon budget 2014

    NASA Astrophysics Data System (ADS)

    Le Quéré, C.; Moriarty, R.; Andrew, R. M.; Peters, G. P.; Ciais, P.; Friedlingstein, P.; Jones, S. D.; Sitch, S.; Tans, P.; Arneth, A.; Boden, T. A.; Bopp, L.; Bozec, Y.; Canadell, J. G.; Chevallier, F.; Cosca, C. E.; Harris, I.; Hoppema, M.; Houghton, R. A.; House, J. I.; Jain, A.; Johannessen, T.; Kato, E.; Keeling, R. F.; Kitidis, V.; Klein Goldewijk, K.; Koven, C.; Landa, C. S.; Landschützer, P.; Lenton, A.; Lima, I. D.; Marland, G.; Mathis, J. T.; Metzl, N.; Nojiri, Y.; Olsen, A.; Ono, T.; Peters, W.; Pfeil, B.; Poulter, B.; Raupach, M. R.; Regnier, P.; Rödenbeck, C.; Saito, S.; Salisbury, J. E.; Schuster, U.; Schwinger, J.; Séférian, R.; Segschneider, J.; Steinhoff, T.; Stocker, B. D.; Sutton, A. J.; Takahashi, T.; Tilbrook, B.; van der Werf, G. R.; Viovy, N.; Wang, Y.-P.; Wanninkhof, R.; Wiltshire, A.; Zeng, N.

    2014-09-01

    Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe datasets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates, consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil fuel combustion and cement production (EFF) are based on energy statistics and cement production data, respectively, while emissions from Land-Use Change (ELUC), mainly deforestation, are based on combined evidence from land-cover change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent Dynamic Global Vegetation Models forced by observed climate, CO2 and land cover change (some including nitrogen-carbon interactions). We compare the variability and mean land and ocean fluxes to estimates from three atmospheric inverse methods for three broad latitude bands. All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each component of

  7. Differential equation based method for accurate approximations in optimization

    NASA Technical Reports Server (NTRS)

    Pritchard, Jocelyn I.; Adelman, Howard M.

    1990-01-01

    A method to efficiently and accurately approximate the effect of design changes on structural response is described. The key to this method is to interpret sensitivity equations as differential equations that may be solved explicitly for closed form approximations, hence, the method is denoted the Differential Equation Based (DEB) method. Approximations were developed for vibration frequencies, mode shapes and static displacements. The DEB approximation method was applied to a cantilever beam and results compared with the commonly-used linear Taylor series approximations and exact solutions. The test calculations involved perturbing the height, width, cross-sectional area, tip mass, and bending inertia of the beam. The DEB method proved to be very accurate, and in most cases, was more accurate than the linear Taylor series approximation. The method is applicable to simultaneous perturbation of several design variables. Also, the approximations may be used to calculate other system response quantities. For example, the approximations for displacements are used to approximate bending stresses.

  8. Efficient Global Aerodynamic Modeling from Flight Data

    NASA Technical Reports Server (NTRS)

    Morelli, Eugene A.

    2012-01-01

    A method for identifying global aerodynamic models from flight data in an efficient manner is explained and demonstrated. A novel experiment design technique was used to obtain dynamic flight data over a range of flight conditions with a single flight maneuver. Multivariate polynomials and polynomial splines were used with orthogonalization techniques and statistical modeling metrics to synthesize global nonlinear aerodynamic models directly and completely from flight data alone. Simulation data and flight data from a subscale twin-engine jet transport aircraft were used to demonstrate the techniques. Results showed that global multivariate nonlinear aerodynamic dependencies could be accurately identified using flight data from a single maneuver. Flight-derived global aerodynamic model structures, model parameter estimates, and associated uncertainties were provided for all six nondimensional force and moment coefficients for the test aircraft. These models were combined with a propulsion model identified from engine ground test data to produce a high-fidelity nonlinear flight simulation very efficiently. Prediction testing using a multi-axis maneuver showed that the identified global model accurately predicted aircraft responses.

  9. Accurate upwind-monotone (nonoscillatory) methods for conservation laws

    NASA Technical Reports Server (NTRS)

    Huynh, Hung T.

    1992-01-01

    The well known MUSCL scheme of Van Leer is constructed using a piecewise linear approximation. The MUSCL scheme is second order accurate at the smooth part of the solution except at extrema where the accuracy degenerates to first order due to the monotonicity constraint. To construct accurate schemes which are free from oscillations, the author introduces the concept of upwind monotonicity. Several classes of schemes, which are upwind monotone and of uniform second or third order accuracy are then presented. Results for advection with constant speed are shown. It is also shown that the new scheme compares favorably with state of the art methods.

  10. Accurate stress resultants equations for laminated composite deep thick shells

    SciTech Connect

    Qatu, M.S.

    1995-11-01

    This paper derives accurate equations for the normal and shear force as well as bending and twisting moment resultants for laminated composite deep, thick shells. The stress resultant equations for laminated composite thick shells are shown to be different from those of plates. This is due to the fact the stresses over the thickness of the shell have to be integrated on a trapezoidal-like shell element to obtain the stress resultants. Numerical results are obtained and showed that accurate stress resultants are needed for laminated composite deep thick shells, especially if the curvature is not spherical.

  11. Must Kohn-Sham oscillator strengths be accurate at threshold?

    SciTech Connect

    Yang Zenghui; Burke, Kieron; Faassen, Meta van

    2009-09-21

    The exact ground-state Kohn-Sham (KS) potential for the helium atom is known from accurate wave function calculations of the ground-state density. The threshold for photoabsorption from this potential matches the physical system exactly. By carefully studying its absorption spectrum, we show the answer to the title question is no. To address this problem in detail, we generate a highly accurate simple fit of a two-electron spectrum near the threshold, and apply the method to both the experimental spectrum and that of the exact ground-state Kohn-Sham potential.

  12. Fast and Accurate Construction of Ultra-Dense Consensus Genetic Maps Using Evolution Strategy Optimization

    PubMed Central

    Mester, David; Ronin, Yefim; Schnable, Patrick; Aluru, Srinivas; Korol, Abraham

    2015-01-01

    Our aim was to develop a fast and accurate algorithm for constructing consensus genetic maps for chip-based SNP genotyping data with a high proportion of shared markers between mapping populations. Chip-based genotyping of SNP markers allows producing high-density genetic maps with a relatively standardized set of marker loci for different mapping populations. The availability of a standard high-throughput mapping platform simplifies consensus analysis by ignoring unique markers at the stage of consensus mapping thereby reducing mathematical complicity of the problem and in turn analyzing bigger size mapping data using global optimization criteria instead of local ones. Our three-phase analytical scheme includes automatic selection of ~100-300 of the most informative (resolvable by recombination) markers per linkage group, building a stable skeletal marker order for each data set and its verification using jackknife re-sampling, and consensus mapping analysis based on global optimization criterion. A novel Evolution Strategy optimization algorithm with a global optimization criterion presented in this paper is able to generate high quality, ultra-dense consensus maps, with many thousands of markers per genome. This algorithm utilizes "potentially good orders" in the initial solution and in the new mutation procedures that generate trial solutions, enabling to obtain a consensus order in reasonable time. The developed algorithm, tested on a wide range of simulated data and real world data (Arabidopsis), outperformed two tested state-of-the-art algorithms by mapping accuracy and computation time. PMID:25867943

  13. Global Neurosurgery: The Unmet Need.

    PubMed

    Park, Kee B; Johnson, Walter D; Dempsey, Robert J

    2016-04-01

    Globally, the lack of access to basic surgical care causes 3 times as much deaths as HIV/AIDS, tuberculosis, and malaria combined. The magnitude of this unmet need has been described recently, and the numbers are startling. Major shifts in global health agenda have highlighted access to essential and emergency surgery as a high priority. A broad examination of the current global neurosurgical efforts to improve access has revealed some strengths, particularly in the realm of training; however, the demand grossly outstrips the supply; most people in low-income countries do not have access to basic surgical care, either due to lack of availability or affordability. Projects that help create a robust and resilient health system within low- and middle-income countries require urgent implementation. In this context, concurrent scale-up of human resources, investments in capacity building, local data collection, and analysis for accurate assessment are essential. In addition, through process of collaboration and consensus building within the neurosurgical community, a unified voice of neurosurgery is necessary to effectively advocate for all those who need neurosurgical care wherever, whenever. PMID:26732963

  14. Rising temperatures reduce global wheat production

    NASA Astrophysics Data System (ADS)

    Asseng, S.; Ewert, F.; Martre, P.; Rötter, R. P.; Lobell, D. B.; Cammarano, D.; Kimball, B. A.; Ottman, M. J.; Wall, G. W.; White, J. W.; Reynolds, M. P.; Alderman, P. D.; Prasad, P. V. V.; Aggarwal, P. K.; Anothai, J.; Basso, B.; Biernath, C.; Challinor, A. J.; de Sanctis, G.; Doltra, J.; Fereres, E.; Garcia-Vila, M.; Gayler, S.; Hoogenboom, G.; Hunt, L. A.; Izaurralde, R. C.; Jabloun, M.; Jones, C. D.; Kersebaum, K. C.; Koehler, A.-K.; Müller, C.; Naresh Kumar, S.; Nendel, C.; O'Leary, G.; Olesen, J. E.; Palosuo, T.; Priesack, E.; Eyshi Rezaei, E.; Ruane, A. C.; Semenov, M. A.; Shcherbak, I.; Stöckle, C.; Stratonovitch, P.; Streck, T.; Supit, I.; Tao, F.; Thorburn, P. J.; Waha, K.; Wang, E.; Wallach, D.; Wolf, J.; Zhao, Z.; Zhu, Y.

    2015-02-01

    Crop models are essential tools for assessing the threat of climate change to local and global food production. Present models used to predict wheat grain yield are highly uncertain when simulating how crops respond to temperature. Here we systematically tested 30 different wheat crop models of the Agricultural Model Intercomparison and Improvement Project against field experiments in which growing season mean temperatures ranged from 15 °C to 32 °C, including experiments with artificial heating. Many models simulated yields well, but were less accurate at higher temperatures. The model ensemble median was consistently more accurate in simulating the crop temperature response than any single model, regardless of the input information used. Extrapolating the model ensemble temperature response indicates that warming is already slowing yield gains at a majority of wheat-growing locations. Global wheat production is estimated to fall by 6% for each °C of further temperature increase and become more variable over space and time.

  15. Rising Temperatures Reduce Global Wheat Production

    NASA Technical Reports Server (NTRS)

    Asseng, S.; Ewert, F.; Martre, P.; Rötter, R. P.; Lobell, D. B.; Cammarano, D.; Kimball, B. A.; Ottman, M. J.; Wall, G. W.; White, J. W.; Reynolds, M. P.; Alderman, P. D.; Prasad, P. V. V.; Aggarwal, P. K.; Anothai, J.; Basso, B.; Biernath, C.; Challinor, A. J.; De Sanctis, G.; Doltra, J.; Fereres, E.; Garcia-Vila, M.; Gayler, S.; Hoogenboom, G.; Hunt, L. A.; Izaurralde, R. C.; Jabloun, M.; C. D. Jones,; Kersebaum, K. C.; Koehler, A-K.; Müller, C.; Naresh Kumar, S.; Nendel, C.; O’Leary, G.; Olesen, J. E.; Palosuo, T.; Priesack, E.; Eyshi Rezaei, E.; Ruane, A. C.; Semenov, M. A.; Shcherbak, I.; Stöckle, C.; Stratonovitch, P.; Streck, T.; Supit, I.; Tao, F.; Thorburn, P. J.; Waha, K.; Wang, E.; Wallach, D.; Wolf, J.; Zhao, Z.; Zhu, Y.

    2015-01-01

    Crop models are essential tools for assessing the threat of climate change to local and global food production. Present models used to predict wheat grain yield are highly uncertain when simulating how crops respond to temperature. Here we systematically tested 30 different wheat crop models of the Agricultural Model Intercomparison and Improvement Project against field experiments in which growing season mean temperatures ranged from 15 degrees C to 32? degrees C, including experiments with artificial heating. Many models simulated yields well, but were less accurate at higher temperatures. The model ensemble median was consistently more accurate in simulating the crop temperature response than any single model, regardless of the input information used. Extrapolating the model ensemble temperature response indicates that warming is already slowing yield gains at a majority of wheat-growing locations. Global wheat production is estimated to fall by 6% for each degree C of further temperature increase and become more variable over space and time.

  16. Global emissions inventories to aid atmospheric modelers

    NASA Astrophysics Data System (ADS)

    Graedel, T. E.

    Computer projections of changes in global atmospheric chemistry could become more accurate and more easily compared with the availability of standard global emissions inventories. Starting in 1994, the Global Emissions Inventory Activity (GEIA) began to finalize gridded global emissions inventories and distribute them to atmospheric scientists. GEIA operates under the auspices of the International Global Atmospheric Chemistry (IGAC) Project, a cooperative effort of several hundred atmospheric scientists from more than 30 countries. The purpose of the IGAC Project is to measure, understand, and predict changes in global atmospheric chemistry, particularly those contributing to global problems such as acid rain, depletion of stratospheric ozone, greenhouse warming, and increased oxidant levels that damage biota.A 1992 survey by participants in the GEIA project [Graedel et al., 1993] showed that suitable emissions inventories are rarely available. The chlorofluorocarbon inventory, regarded as well quantified, was unavailable in gridded form. Inventories for CO2, CH4, NOx, SO2, reduced sulfur, and radon were regarded as having excess uncertainty, inadequate spatial resolution, or both; inventories for other chemical species were sketchy or nonexistent. Temporal resolution was almost uniformly poor. The survey made it clear that internally consistent, rigorously developed, gridded inventories with adequate spatial and temporal resolution would be valuable.

  17. Transforming Academic Globalization into Globalization for All

    ERIC Educational Resources Information Center

    Ramalhoto, M. F.

    2006-01-01

    Driving innovation and continuous improvement with regard to ecological, environmental and human sustainability is essential for win-win globalization. That calls for research on strategic and monitoring planning to manage globalization and technological and scientific change. This paper describes a new basic function of the university institution…

  18. Monitoring circuit accurately measures movement of solenoid valve

    NASA Technical Reports Server (NTRS)

    Gillett, J. D.

    1966-01-01

    Solenoid operated valve in a control system powered by direct current issued to accurately measure the valve travel. This system is currently in operation with a 28-vdc power system used for control of fluids in liquid rocket motor test facilities.

  19. A Self-Instructional Device for Conditioning Accurate Prosody.

    ERIC Educational Resources Information Center

    Buiten, Roger; Lane, Harlan

    1965-01-01

    A self-instructional device for conditioning accurate prosody in second-language learning is described in this article. The Speech Auto-Instructional Device (SAID) is electro-mechanical and performs three functions: SAID (1) presents to the student tape-recorded pattern sentences that are considered standards in prosodic performance; (2) processes…

  20. Second-order accurate nonoscillatory schemes for scalar conservation laws

    NASA Technical Reports Server (NTRS)

    Huynh, Hung T.

    1989-01-01

    Explicit finite difference schemes for the computation of weak solutions of nonlinear scalar conservation laws is presented and analyzed. These schemes are uniformly second-order accurate and nonoscillatory in the sense that the number of extrema of the discrete solution is not increasing in time.

  1. Bioaccessibility tests accurately estimate bioavailability of lead to quail

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hazards of soil-borne Pb to wild birds may be more accurately quantified if the bioavailability of that Pb is known. To better understand the bioavailability of Pb, we incorporated Pb-contaminated soils or Pb acetate into diets for Japanese quail (Coturnix japonica), fed the quail for 15 days, and ...

  2. Accurately Detecting Students' Lies regarding Relational Aggression by Correctional Instructions

    ERIC Educational Resources Information Center

    Dickhauser, Oliver; Reinhard, Marc-Andre; Marksteiner, Tamara

    2012-01-01

    This study investigates the effect of correctional instructions when detecting lies about relational aggression. Based on models from the field of social psychology, we predict that correctional instruction will lead to a less pronounced lie bias and to more accurate lie detection. Seventy-five teachers received videotapes of students' true denial…

  3. Accurate Measurements of the Local Deuterium Abundance from HST Spectra

    NASA Technical Reports Server (NTRS)

    Linsky, Jeffrey L.

    1996-01-01

    An accurate measurement of the primordial value of D/H would provide a critical test of nucleosynthesis models for the early universe and the baryon density. I briefly summarize the ongoing HST observations of the interstellar H and D Lyman-alpha absorption for lines of sight to nearby stars and comment on recent reports of extragalactic D/H measurements.

  4. Quantifying Accurate Calorie Estimation Using the "Think Aloud" Method

    ERIC Educational Resources Information Center

    Holmstrup, Michael E.; Stearns-Bruening, Kay; Rozelle, Jeffrey

    2013-01-01

    Objective: Clients often have limited time in a nutrition education setting. An improved understanding of the strategies used to accurately estimate calories may help to identify areas of focused instruction to improve nutrition knowledge. Methods: A "Think Aloud" exercise was recorded during the estimation of calories in a standard dinner meal…

  5. Benchmarking accurate spectral phase retrieval of single attosecond pulses

    NASA Astrophysics Data System (ADS)

    Wei, Hui; Le, Anh-Thu; Morishita, Toru; Yu, Chao; Lin, C. D.

    2015-02-01

    A single extreme-ultraviolet (XUV) attosecond pulse or pulse train in the time domain is fully characterized if its spectral amplitude and phase are both determined. The spectral amplitude can be easily obtained from photoionization of simple atoms where accurate photoionization cross sections have been measured from, e.g., synchrotron radiations. To determine the spectral phase, at present the standard method is to carry out XUV photoionization in the presence of a dressing infrared (IR) laser. In this work, we examine the accuracy of current phase retrieval methods (PROOF and iPROOF) where the dressing IR is relatively weak such that photoelectron spectra can be accurately calculated by second-order perturbation theory. We suggest a modified method named swPROOF (scattering wave phase retrieval by omega oscillation filtering) which utilizes accurate one-photon and two-photon dipole transition matrix elements and removes the approximations made in PROOF and iPROOF. We show that the swPROOF method can in general retrieve accurate spectral phase compared to other simpler models that have been suggested. We benchmark the accuracy of these phase retrieval methods through simulating the spectrogram by solving the time-dependent Schrödinger equation numerically using several known single attosecond pulses with a fixed spectral amplitude but different spectral phases.

  6. BIOACCESSIBILITY TESTS ACCURATELY ESTIMATE BIOAVAILABILITY OF LEAD TO QUAIL

    EPA Science Inventory

    Hazards of soil-borne Pb to wild birds may be more accurately quantified if the bioavailability of that Pb is known. To better understand the bioavailability of Pb to birds, we measured blood Pb concentrations in Japanese quail (Coturnix japonica) fed diets containing Pb-contami...

  7. Device accurately measures and records low gas-flow rates

    NASA Technical Reports Server (NTRS)

    Branum, L. W.

    1966-01-01

    Free-floating piston in a vertical column accurately measures and records low gas-flow rates. The system may be calibrated, using an adjustable flow-rate gas supply, a low pressure gage, and a sequence recorder. From the calibration rates, a nomograph may be made for easy reduction. Temperature correction may be added for further accuracy.

  8. A Simple and Accurate Method for Measuring Enzyme Activity.

    ERIC Educational Resources Information Center

    Yip, Din-Yan

    1997-01-01

    Presents methods commonly used for investigating enzyme activity using catalase and presents a new method for measuring catalase activity that is more reliable and accurate. Provides results that are readily reproduced and quantified. Can also be used for investigations of enzyme properties such as the effects of temperature, pH, inhibitors,…

  9. Precise and Accurate Density Determination of Explosives Using Hydrostatic Weighing

    SciTech Connect

    B. Olinger

    2005-07-01

    Precise and accurate density determination requires weight measurements in air and water using sufficiently precise analytical balances, knowledge of the densities of air and water, knowledge of thermal expansions, availability of a density standard, and a method to estimate the time to achieve thermal equilibrium with water. Density distributions in pressed explosives are inferred from the densities of elements from a central slice.

  10. Is a Writing Sample Necessary for "Accurate Placement"?

    ERIC Educational Resources Information Center

    Sullivan, Patrick; Nielsen, David

    2009-01-01

    The scholarship about assessment for placement is extensive and notoriously ambiguous. Foremost among the questions that continue to be unresolved in this scholarship is this one: Is a writing sample necessary for "accurate placement"? Using a robust data sample of student assessment essays and ACCUPLACER test scores, we put this question to the…

  11. Efficient and accurate sound propagation using adaptive rectangular decomposition.

    PubMed

    Raghuvanshi, Nikunj; Narain, Rahul; Lin, Ming C

    2009-01-01

    Accurate sound rendering can add significant realism to complement visual display in interactive applications, as well as facilitate acoustic predictions for many engineering applications, like accurate acoustic analysis for architectural design. Numerical simulation can provide this realism most naturally by modeling the underlying physics of wave propagation. However, wave simulation has traditionally posed a tough computational challenge. In this paper, we present a technique which relies on an adaptive rectangular decomposition of 3D scenes to enable efficient and accurate simulation of sound propagation in complex virtual environments. It exploits the known analytical solution of the Wave Equation in rectangular domains, and utilizes an efficient implementation of the Discrete Cosine Transform on Graphics Processors (GPU) to achieve at least a 100-fold performance gain compared to a standard Finite-Difference Time-Domain (FDTD) implementation with comparable accuracy, while also being 10-fold more memory efficient. Consequently, we are able to perform accurate numerical acoustic simulation on large, complex scenes in the kilohertz range. To the best of our knowledge, it was not previously possible to perform such simulations on a desktop computer. Our work thus enables acoustic analysis on large scenes and auditory display for complex virtual environments on commodity hardware. PMID:19590105

  12. Accurate momentum transfer cross section for the attractive Yukawa potential

    SciTech Connect

    Khrapak, S. A.

    2014-04-15

    Accurate expression for the momentum transfer cross section for the attractive Yukawa potential is proposed. This simple analytic expression agrees with the numerical results better than to within ±2% in the regime relevant for ion-particle collisions in complex (dusty) plasmas.

  13. Instrument accurately measures small temperature changes on test surface

    NASA Technical Reports Server (NTRS)

    Harvey, W. D.; Miller, H. B.

    1966-01-01

    Calorimeter apparatus accurately measures very small temperature rises on a test surface subjected to aerodynamic heating. A continuous thin sheet of a sensing material is attached to a base support plate through which a series of holes of known diameter have been drilled for attaching thermocouples to the material.

  14. On the importance of having accurate data for astrophysical modelling

    NASA Astrophysics Data System (ADS)

    Lique, Francois

    2016-06-01

    The Herschel telescope and the ALMA and NOEMA interferometers have opened new windows of observation for wavelengths ranging from far infrared to sub-millimeter with spatial and spectral resolutions previously unmatched. To make the most of these observations, an accurate knowledge of the physical and chemical processes occurring in the interstellar and circumstellar media is essential.In this presentation, I will discuss what are the current needs of astrophysics in terms of molecular data and I will show that accurate molecular data are crucial for the proper determination of the physical conditions in molecular clouds.First, I will focus on collisional excitation studies that are needed for molecular lines modelling beyond the Local Thermodynamic Equilibrium (LTE) approach. In particular, I will show how new collisional data for the HCN and HNC isomers, two tracers of star forming conditions, have allowed solving the problem of their respective abundance in cold molecular clouds. I will also present the last collisional data that have been computed in order to analyse new highly resolved observations provided by the ALMA interferometer.Then, I will present the calculation of accurate rate constants for the F+H2 → HF+H and Cl+H2 ↔ HCl+H reactions, which have allowed a more accurate determination of the physical conditions in diffuse molecular clouds. I will also present the recent work on the ortho-para-H2 conversion due to hydrogen exchange that allow more accurate determination of the ortho-to-para-H2 ratio in the universe and that imply a significant revision of the cooling mechanism in astrophysical media.

  15. Global Tuberculosis Report 2015

    MedlinePlus

    ... Feed Youtube Twitter Facebook Google + iTunes Play Store Tuberculosis (TB) Menu Tuberculosis The End TB Strategy Areas ... data News, events and features About us Global tuberculosis report 2015 This is the twentieth global report ...

  16. Global Health Observatory (GHO)

    MedlinePlus

    ... repository Reports Country statistics Map gallery Standards Global Health Observatory (GHO) data Monitoring health for the SDGs ... relevant web pages on the theme. Monitoring the health goal: indicators of overall progress Mortality and global ...

  17. IMERG Global Precipitation Rates

    NASA Video Gallery

    NASA's Global Precipitation Measurement mission has produced its first global map of rainfall and snowfall. The GPM Core Observatory launched one year ago on Feb. 27, 2014 as a collaboration betwee...

  18. Global Atmospheric Aerosol Modeling

    NASA Technical Reports Server (NTRS)

    Hendricks, Johannes; Aquila, Valentina; Righi, Mattia

    2012-01-01

    Global aerosol models are used to study the distribution and properties of atmospheric aerosol particles as well as their effects on clouds, atmospheric chemistry, radiation, and climate. The present article provides an overview of the basic concepts of global atmospheric aerosol modeling and shows some examples from a global aerosol simulation. Particular emphasis is placed on the simulation of aerosol particles and their effects within global climate models.

  19. Accurate modeling of switched reluctance machine based on hybrid trained WNN

    SciTech Connect

    Song, Shoujun Ge, Lefei; Ma, Shaojie; Zhang, Man

    2014-04-15

    According to the strong nonlinear electromagnetic characteristics of switched reluctance machine (SRM), a novel accurate modeling method is proposed based on hybrid trained wavelet neural network (WNN) which combines improved genetic algorithm (GA) with gradient descent (GD) method to train the network. In the novel method, WNN is trained by GD method based on the initial weights obtained per improved GA optimization, and the global parallel searching capability of stochastic algorithm and local convergence speed of deterministic algorithm are combined to enhance the training accuracy, stability and speed. Based on the measured electromagnetic characteristics of a 3-phase 12/8-pole SRM, the nonlinear simulation model is built by hybrid trained WNN in Matlab. The phase current and mechanical characteristics from simulation under different working conditions meet well with those from experiments, which indicates the accuracy of the model for dynamic and static performance evaluation of SRM and verifies the effectiveness of the proposed modeling method.

  20. Accurate, efficient, and (iso)geometrically flexible collocation methods for phase-field models

    NASA Astrophysics Data System (ADS)

    Gomez, Hector; Reali, Alessandro; Sangalli, Giancarlo

    2014-04-01

    We propose new collocation methods for phase-field models. Our algorithms are based on isogeometric analysis, a new technology that makes use of functions from computational geometry, such as, for example, Non-Uniform Rational B-Splines (NURBS). NURBS exhibit excellent approximability and controllable global smoothness, and can represent exactly most geometries encapsulated in Computer Aided Design (CAD) models. These attributes permitted us to derive accurate, efficient, and geometrically flexible collocation methods for phase-field models. The performance of our method is demonstrated by several numerical examples of phase separation modeled by the Cahn-Hilliard equation. We feel that our method successfully combines the geometrical flexibility of finite elements with the accuracy and simplicity of pseudo-spectral collocation methods, and is a viable alternative to classical collocation methods.

  1. Global tectonics and space geodesy.

    PubMed

    Gordon, R G; Stein, S

    1992-04-17

    Much of the success of plate tectonics can be attributed to the near rigidity of tectonic plates and the availability of data that describe the rates and directions of motion across narrow plate boundaries \\m=~\\1 to 60 kilometers wide. Nonetheless, many plate boundaries in both continental and oceanic lithosphere are not narrow but are hundreds to thousands of kilometers wide. Wide plate boundary zones cover \\m=~\\15 percent of Earth's surface area. Space geodesy, which includes very long baseline radio interferometry, satellite laser ranging, and the global positioning system, is providing the accurate long-distance measurements needed to estimate the present motion across and within wide plate boundary zones. Space geodetic data show that plate velocities averaged over years are remarkably similar to velocities averaged over millions of years. PMID:17743109

  2. Global tectonics and space geodesy

    NASA Technical Reports Server (NTRS)

    Gordon, Richard G.; Stein, Seth

    1992-01-01

    Much of the success of plate tectonics can be attributed to the near rigidity of tectonic plates and the availability of data that describe the rates and directions of motion across narrow plate boundaries of about 1 to 60 kilometers. Nonetheless, many plate boundaries in both continental and oceanic lithosphere are not narrow but are hundreds to thousands of kilometers wide. Wide plate boundary zones cover approximately 15 percent of earth's surface area. Space geodesy, which includes very long baseline radio interferometry, satellite laser ranging, and the global positioning system, provides the accurate long-distance measurements needed to estimate the present motion across and within wide plate boundary zones. Space geodetic data show that plate velocities averaged over years are remarkably similar to velocities avaraged over millions of years.

  3. SUMOylation in Control of Accurate Chromosome Segregation during Mitosis

    PubMed Central

    Wan, Jun; Subramonian, Divya; Zhang, Xiang-Dong

    2012-01-01

    Posttranslational protein modification by small ubiquitin-related modifier (SUMO) has emerged as an important regulatory mechanism for chromosome segregation during mitosis. This review focuses on how SUMOylation regulates the centromere and kinetochore activities to achieve accurate chromosome segregation during mitosis. Kinetochores are assembled on the specialized chromatin domains called centromeres and serve as the sites for attaching spindle microtubule to segregate sister chromatids to daughter cells. Many proteins associated with mitotic centromeres and kinetochores have been recently found to be modified by SUMO. Although we are still at the early stage of elucidating how SUMOylation controls chromosome segregation during mitosis, a substantial progress has been achieved over the past decade. Furthermore, a major theme that has emerged from the recent studies of SUMOylation in mitosis is that both SUMO conjugation and deconjugation are critical for kinetochore assembly and disassembly. Lastly, we propose a model that SUMOylation coordinates multiple centromere and kinetochore activities to ensure accurate chromosome segregation. PMID:22812528

  4. Accurate and robust estimation of camera parameters using RANSAC

    NASA Astrophysics Data System (ADS)

    Zhou, Fuqiang; Cui, Yi; Wang, Yexin; Liu, Liu; Gao, He

    2013-03-01

    Camera calibration plays an important role in the field of machine vision applications. The popularly used calibration approach based on 2D planar target sometimes fails to give reliable and accurate results due to the inaccurate or incorrect localization of feature points. To solve this problem, an accurate and robust estimation method for camera parameters based on RANSAC algorithm is proposed to detect the unreliability and provide the corresponding solutions. Through this method, most of the outliers are removed and the calibration errors that are the main factors influencing measurement accuracy are reduced. Both simulative and real experiments have been carried out to evaluate the performance of the proposed method and the results show that the proposed method is robust under large noise condition and quite efficient to improve the calibration accuracy compared with the original state.

  5. Accurate Development of Thermal Neutron Scattering Cross Section Libraries

    SciTech Connect

    Hawari, Ayman; Dunn, Michael

    2014-06-10

    The objective of this project is to develop a holistic (fundamental and accurate) approach for generating thermal neutron scattering cross section libraries for a collection of important enutron moderators and reflectors. The primary components of this approach are the physcial accuracy and completeness of the generated data libraries. Consequently, for the first time, thermal neutron scattering cross section data libraries will be generated that are based on accurate theoretical models, that are carefully benchmarked against experimental and computational data, and that contain complete covariance information that can be used in propagating the data uncertainties through the various components of the nuclear design and execution process. To achieve this objective, computational and experimental investigations will be performed on a carefully selected subset of materials that play a key role in all stages of the nuclear fuel cycle.

  6. Accurate adjoint design sensitivities for nano metal optics.

    PubMed

    Hansen, Paul; Hesselink, Lambertus

    2015-09-01

    We present a method for obtaining accurate numerical design sensitivities for metal-optical nanostructures. Adjoint design sensitivity analysis, long used in fluid mechanics and mechanical engineering for both optimization and structural analysis, is beginning to be used for nano-optics design, but it fails for sharp-cornered metal structures because the numerical error in electromagnetic simulations of metal structures is highest at sharp corners. These locations feature strong field enhancement and contribute strongly to design sensitivities. By using high-accuracy FEM calculations and rounding sharp features to a finite radius of curvature we obtain highly-accurate design sensitivities for 3D metal devices. To provide a bridge to the existing literature on adjoint methods in other fields, we derive the sensitivity equations for Maxwell's equations in the PDE framework widely used in fluid mechanics. PMID:26368483

  7. An Accurate Link Correlation Estimator for Improving Wireless Protocol Performance

    PubMed Central

    Zhao, Zhiwei; Xu, Xianghua; Dong, Wei; Bu, Jiajun

    2015-01-01

    Wireless link correlation has shown significant impact on the performance of various sensor network protocols. Many works have been devoted to exploiting link correlation for protocol improvements. However, the effectiveness of these designs heavily relies on the accuracy of link correlation measurement. In this paper, we investigate state-of-the-art link correlation measurement and analyze the limitations of existing works. We then propose a novel lightweight and accurate link correlation estimation (LACE) approach based on the reasoning of link correlation formation. LACE combines both long-term and short-term link behaviors for link correlation estimation. We implement LACE as a stand-alone interface in TinyOS and incorporate it into both routing and flooding protocols. Simulation and testbed results show that LACE: (1) achieves more accurate and lightweight link correlation measurements than the state-of-the-art work; and (2) greatly improves the performance of protocols exploiting link correlation. PMID:25686314

  8. Light Field Imaging Based Accurate Image Specular Highlight Removal

    PubMed Central

    Wang, Haoqian; Xu, Chenxue; Wang, Xingzheng; Zhang, Yongbing; Peng, Bo

    2016-01-01

    Specular reflection removal is indispensable to many computer vision tasks. However, most existing methods fail or degrade in complex real scenarios for their individual drawbacks. Benefiting from the light field imaging technology, this paper proposes a novel and accurate approach to remove specularity and improve image quality. We first capture images with specularity by the light field camera (Lytro ILLUM). After accurately estimating the image depth, a simple and concise threshold strategy is adopted to cluster the specular pixels into “unsaturated” and “saturated” category. Finally, a color variance analysis of multiple views and a local color refinement are individually conducted on the two categories to recover diffuse color information. Experimental evaluation by comparison with existed methods based on our light field dataset together with Stanford light field archive verifies the effectiveness of our proposed algorithm. PMID:27253083

  9. Local Debonding and Fiber Breakage in Composite Materials Modeled Accurately

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Arnold, Steven M.

    2001-01-01

    A prerequisite for full utilization of composite materials in aerospace components is accurate design and life prediction tools that enable the assessment of component performance and reliability. Such tools assist both structural analysts, who design and optimize structures composed of composite materials, and materials scientists who design and optimize the composite materials themselves. NASA Glenn Research Center's Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) software package (http://www.grc.nasa.gov/WWW/LPB/mac) addresses this need for composite design and life prediction tools by providing a widely applicable and accurate approach to modeling composite materials. Furthermore, MAC/GMC serves as a platform for incorporating new local models and capabilities that are under development at NASA, thus enabling these new capabilities to progress rapidly to a stage in which they can be employed by the code's end users.

  10. Fixed-Wing Micro Aerial Vehicle for Accurate Corridor Mapping

    NASA Astrophysics Data System (ADS)

    Rehak, M.; Skaloud, J.

    2015-08-01

    In this study we present a Micro Aerial Vehicle (MAV) equipped with precise position and attitude sensors that together with a pre-calibrated camera enables accurate corridor mapping. The design of the platform is based on widely available model components to which we integrate an open-source autopilot, customized mass-market camera and navigation sensors. We adapt the concepts of system calibration from larger mapping platforms to MAV and evaluate them practically for their achievable accuracy. We present case studies for accurate mapping without ground control points: first for a block configuration, later for a narrow corridor. We evaluate the mapping accuracy with respect to checkpoints and digital terrain model. We show that while it is possible to achieve pixel (3-5 cm) mapping accuracy in both cases, precise aerial position control is sufficient for block configuration, the precise position and attitude control is required for corridor mapping.

  11. Multimodal Spatial Calibration for Accurately Registering EEG Sensor Positions

    PubMed Central

    Chen, Shengyong; Xiao, Gang; Li, Xiaoli

    2014-01-01

    This paper proposes a fast and accurate calibration method to calibrate multiple multimodal sensors using a novel photogrammetry system for fast localization of EEG sensors. The EEG sensors are placed on human head and multimodal sensors are installed around the head to simultaneously obtain all EEG sensor positions. A multiple views' calibration process is implemented to obtain the transformations of multiple views. We first develop an efficient local repair algorithm to improve the depth map, and then a special calibration body is designed. Based on them, accurate and robust calibration results can be achieved. We evaluate the proposed method by corners of a chessboard calibration plate. Experimental results demonstrate that the proposed method can achieve good performance, which can be further applied to EEG source localization applications on human brain. PMID:24803954

  12. Accurate nuclear radii and binding energies from a chiral interaction

    DOE PAGESBeta

    Ekstrom, Jan A.; Jansen, G. R.; Wendt, Kyle A.; Hagen, Gaute; Papenbrock, Thomas F.; Carlsson, Boris; Forssen, Christian; Hjorth-Jensen, M.; Navratil, Petr; Nazarewicz, Witold

    2015-05-01

    With the goal of developing predictive ab initio capability for light and medium-mass nuclei, two-nucleon and three-nucleon forces from chiral effective field theory are optimized simultaneously to low-energy nucleon-nucleon scattering data, as well as binding energies and radii of few-nucleon systems and selected isotopes of carbon and oxygen. Coupled-cluster calculations based on this interaction, named NNLOsat, yield accurate binding energies and radii of nuclei up to 40Ca, and are consistent with the empirical saturation point of symmetric nuclear matter. In addition, the low-lying collective Jπ=3- states in 16O and 40Ca are described accurately, while spectra for selected p- and sd-shellmore » nuclei are in reasonable agreement with experiment.« less

  13. Method for Accurately Calibrating a Spectrometer Using Broadband Light

    NASA Technical Reports Server (NTRS)

    Simmons, Stephen; Youngquist, Robert

    2011-01-01

    A novel method has been developed for performing very fine calibration of a spectrometer. This process is particularly useful for modern miniature charge-coupled device (CCD) spectrometers where a typical factory wavelength calibration has been performed and a finer, more accurate calibration is desired. Typically, the factory calibration is done with a spectral line source that generates light at known wavelengths, allowing specific pixels in the CCD array to be assigned wavelength values. This method is good to about 1 nm across the spectrometer s wavelength range. This new method appears to be accurate to about 0.1 nm, a factor of ten improvement. White light is passed through an unbalanced Michelson interferometer, producing an optical signal with significant spectral variation. A simple theory can be developed to describe this spectral pattern, so by comparing the actual spectrometer output against this predicted pattern, errors in the wavelength assignment made by the spectrometer can be determined.

  14. Accurate nuclear radii and binding energies from a chiral interaction

    SciTech Connect

    Ekstrom, Jan A.; Jansen, G. R.; Wendt, Kyle A.; Hagen, Gaute; Papenbrock, Thomas F.; Carlsson, Boris; Forssen, Christian; Hjorth-Jensen, M.; Navratil, Petr; Nazarewicz, Witold

    2015-05-01

    With the goal of developing predictive ab initio capability for light and medium-mass nuclei, two-nucleon and three-nucleon forces from chiral effective field theory are optimized simultaneously to low-energy nucleon-nucleon scattering data, as well as binding energies and radii of few-nucleon systems and selected isotopes of carbon and oxygen. Coupled-cluster calculations based on this interaction, named NNLOsat, yield accurate binding energies and radii of nuclei up to 40Ca, and are consistent with the empirical saturation point of symmetric nuclear matter. In addition, the low-lying collective Jπ=3- states in 16O and 40Ca are described accurately, while spectra for selected p- and sd-shell nuclei are in reasonable agreement with experiment.

  15. An accurate link correlation estimator for improving wireless protocol performance.

    PubMed

    Zhao, Zhiwei; Xu, Xianghua; Dong, Wei; Bu, Jiajun

    2015-01-01

    Wireless link correlation has shown significant impact on the performance of various sensor network protocols. Many works have been devoted to exploiting link correlation for protocol improvements. However, the effectiveness of these designs heavily relies on the accuracy of link correlation measurement. In this paper, we investigate state-of-the-art link correlation measurement and analyze the limitations of existing works. We then propose a novel lightweight and accurate link correlation estimation (LACE) approach based on the reasoning of link correlation formation. LACE combines both long-term and short-term link behaviors for link correlation estimation. We implement LACE as a stand-alone interface in TinyOS and incorporate it into both routing and flooding protocols. Simulation and testbed results show that LACE: (1) achieves more accurate and lightweight link correlation measurements than the state-of-the-art work; and (2) greatly improves the performance of protocols exploiting link correlation. PMID:25686314

  16. Groundtruth approach to accurate quantitation of fluorescence microarrays

    SciTech Connect

    Mascio-Kegelmeyer, L; Tomascik-Cheeseman, L; Burnett, M S; van Hummelen, P; Wyrobek, A J

    2000-12-01

    To more accurately measure fluorescent signals from microarrays, we calibrated our acquisition and analysis systems by using groundtruth samples comprised of known quantities of red and green gene-specific DNA probes hybridized to cDNA targets. We imaged the slides with a full-field, white light CCD imager and analyzed them with our custom analysis software. Here we compare, for multiple genes, results obtained with and without preprocessing (alignment, color crosstalk compensation, dark field subtraction, and integration time). We also evaluate the accuracy of various image processing and analysis techniques (background subtraction, segmentation, quantitation and normalization). This methodology calibrates and validates our system for accurate quantitative measurement of microarrays. Specifically, we show that preprocessing the images produces results significantly closer to the known ground-truth for these samples.

  17. Multimodal spatial calibration for accurately registering EEG sensor positions.

    PubMed

    Zhang, Jianhua; Chen, Jian; Chen, Shengyong; Xiao, Gang; Li, Xiaoli

    2014-01-01

    This paper proposes a fast and accurate calibration method to calibrate multiple multimodal sensors using a novel photogrammetry system for fast localization of EEG sensors. The EEG sensors are placed on human head and multimodal sensors are installed around the head to simultaneously obtain all EEG sensor positions. A multiple views' calibration process is implemented to obtain the transformations of multiple views. We first develop an efficient local repair algorithm to improve the depth map, and then a special calibration body is designed. Based on them, accurate and robust calibration results can be achieved. We evaluate the proposed method by corners of a chessboard calibration plate. Experimental results demonstrate that the proposed method can achieve good performance, which can be further applied to EEG source localization applications on human brain. PMID:24803954

  18. Note-accurate audio segmentation based on MPEG-7

    NASA Astrophysics Data System (ADS)

    Wellhausen, Jens

    2003-12-01

    Segmenting audio data into the smallest musical components is the basis for many further meta data extraction algorithms. For example, an automatic music transcription system needs to know where the exact boundaries of each tone are. In this paper a note accurate audio segmentation algorithm based on MPEG-7 low level descriptors is introduced. For a reliable detection of different notes, both features in the time and the frequency domain are used. Because of this, polyphonic instrument mixes and even melodies characterized by human voices can be examined with this alogrithm. For testing and verification of the note accurate segmentation, a simple music transcription system was implemented. The dominant frequency within each segment is used to build a MIDI file representing the processed audio data.

  19. The Psychology of Globalization.

    ERIC Educational Resources Information Center

    Arnett, Jeffrey Jensen

    2002-01-01

    Examines the influence of globalization on psychological functioning, describing globalization worldwide and its psychological consequences. Notes that most people now develop bicultural identities that combine local identity with global culture-related identity. Identity confusion is increasing among young people in non-western cultures because…

  20. Developing Successful Global Leaders

    ERIC Educational Resources Information Center

    Training, 2011

    2011-01-01

    Everyone seems to agree the world desperately needs strong leaders who can manage a global workforce and all the inherent challenges that go with it. That's a big part of the raison d'etre for global leadership development programs. But are today's organizations fully utilizing these programs to develop global leaders, and, if so, are they…

  1. Mapping Global Citizenship

    ERIC Educational Resources Information Center

    Stein, Sharon

    2015-01-01

    The demand to cultivate global citizenship is frequently invoked as central to colleges' and universities' internationalization efforts. However, the term "global citizenship" remains undertheorized in the context of U.S. higher education. This article maps and engages three common global citizenship positions--entrepreneurial, liberal…

  2. Globalization and American Education

    ERIC Educational Resources Information Center

    Merriman, William; Nicoletti, Augustine

    2008-01-01

    Globalization is a potent force in today's world. The welfare of the United States is tied to the welfare of other countries by economics, the environment, politics, culture, information, and technology. This paper identifies the implications of globalization for education, presents applications of important aspects of globalization that teachers…

  3. Accurate Method for Determining Adhesion of Cantilever Beams

    SciTech Connect

    Michalske, T.A.; de Boer, M.P.

    1999-01-08

    Using surface micromachined samples, we demonstrate the accurate measurement of cantilever beam adhesion by using test structures which are adhered over long attachment lengths. We show that this configuration has a deep energy well, such that a fracture equilibrium is easily reached. When compared to the commonly used method of determining the shortest attached beam, the present method is much less sensitive to variations in surface topography or to details of capillary drying.

  4. Multigrid time-accurate integration of Navier-Stokes equations

    NASA Technical Reports Server (NTRS)

    Arnone, Andrea; Liou, Meng-Sing; Povinelli, Louis A.

    1993-01-01

    Efficient acceleration techniques typical of explicit steady-state solvers are extended to time-accurate calculations. Stability restrictions are greatly reduced by means of a fully implicit time discretization. A four-stage Runge-Kutta scheme with local time stepping, residual smoothing, and multigridding is used instead of traditional time-expensive factorizations. Some applications to natural and forced unsteady viscous flows show the capability of the procedure.

  5. Shock Emergence in Supernovae: Limiting Cases and Accurate Approximations

    NASA Astrophysics Data System (ADS)

    Ro, Stephen; Matzner, Christopher D.

    2013-08-01

    We examine the dynamics of accelerating normal shocks in stratified planar atmospheres, providing accurate fitting formulae for the scaling index relating shock velocity to the initial density and for the post-shock acceleration factor as functions of the polytropic and adiabatic indices which parameterize the problem. In the limit of a uniform initial atmosphere, there are analytical formulae for these quantities. In the opposite limit of a very steep density gradient, the solutions match the outcome of shock acceleration in exponential atmospheres.

  6. SHOCK EMERGENCE IN SUPERNOVAE: LIMITING CASES AND ACCURATE APPROXIMATIONS

    SciTech Connect

    Ro, Stephen; Matzner, Christopher D.

    2013-08-10

    We examine the dynamics of accelerating normal shocks in stratified planar atmospheres, providing accurate fitting formulae for the scaling index relating shock velocity to the initial density and for the post-shock acceleration factor as functions of the polytropic and adiabatic indices which parameterize the problem. In the limit of a uniform initial atmosphere, there are analytical formulae for these quantities. In the opposite limit of a very steep density gradient, the solutions match the outcome of shock acceleration in exponential atmospheres.

  7. A method for producing large, accurate, economical female molds

    SciTech Connect

    Guenter, A.; Guenter, B.

    1996-11-01

    A process in which lightweight, highly accurate, economical molds can be produced for prototype and low production runs of large parts for use in composites molding has been developed. This has been achieved by developing existing milling technology, using new materials and innovative material applications to CNC mill large female molds directly. Any step that can be eliminated in the mold building process translates into savings in tooling costs through reduced labor and material requirements.

  8. Accurate far-infrared rotational frequencies of carbon monoxide

    NASA Technical Reports Server (NTRS)

    Varberg, Thomas D.; Evenson, Kenneth M.

    1992-01-01

    This study presents high-resolution measurements of the pure rotational absorption spectrum of CO in its ground state for the range J arcsec - 5-37. A least-squares fit to this data set, augmented by previous microwave measurements of the J arcsec = 0-4 rotational transitions in the literature, determined accurate values for the molecular constants. A table of calculated CO rotational frequencies is provided for the range J arcsec = 0-45.

  9. A robust and accurate formulation of molecular and colloidal electrostatics.

    PubMed

    Sun, Qiang; Klaseboer, Evert; Chan, Derek Y C

    2016-08-01

    This paper presents a re-formulation of the boundary integral method for the Debye-Hückel model of molecular and colloidal electrostatics that removes the mathematical singularities that have to date been accepted as an intrinsic part of the conventional boundary integral equation method. The essence of the present boundary regularized integral equation formulation consists of subtracting a known solution from the conventional boundary integral method in such a way as to cancel out the singularities associated with the Green's function. This approach better reflects the non-singular physical behavior of the systems on boundaries with the benefits of the following: (i) the surface integrals can be evaluated accurately using quadrature without any need to devise special numerical integration procedures, (ii) being able to use quadratic or spline function surface elements to represent the surface more accurately and the variation of the functions within each element is represented to a consistent level of precision by appropriate interpolation functions, (iii) being able to calculate electric fields, even at boundaries, accurately and directly from the potential without having to solve hypersingular integral equations and this imparts high precision in calculating the Maxwell stress tensor and consequently, intermolecular or colloidal forces, (iv) a reliable way to handle geometric configurations in which different parts of the boundary can be very close together without being affected by numerical instabilities, therefore potentials, fields, and forces between surfaces can be found accurately at surface separations down to near contact, and (v) having the simplicity of a formulation that does not require complex algorithms to handle singularities will result in significant savings in coding effort and in the reduction of opportunities for coding errors. These advantages are illustrated using examples drawn from molecular and colloidal electrostatics. PMID:27497538

  10. Strategy Guideline. Accurate Heating and Cooling Load Calculations

    SciTech Connect

    Burdick, Arlan

    2011-06-01

    This guide presents the key criteria required to create accurate heating and cooling load calculations and offers examples of the implications when inaccurate adjustments are applied to the HVAC design process. The guide shows, through realistic examples, how various defaults and arbitrary safety factors can lead to significant increases in the load estimate. Emphasis is placed on the risks incurred from inaccurate adjustments or ignoring critical inputs of the load calculation.

  11. A time-accurate multiple-grid algorithm

    NASA Technical Reports Server (NTRS)

    Jespersen, D. C.

    1985-01-01

    A time-accurate multiple-grid algorithm is described. The algorithm allows one to take much larger time steps with an explicit time-marching scheme than would otherwise be the case. Sample calculations of a scalar advection equation and the Euler equations for an oscillating airfoil are shown. For the oscillating airfoil, time steps an order of magnitude larger than the single-grid algorithm are possible.

  12. Accurate equilibrium structures of fluoro- and chloroderivatives of methane

    NASA Astrophysics Data System (ADS)

    Vogt, Natalja; Demaison, Jean; Rudolph, Heinz Dieter

    2014-11-01

    This work is a systematic study of molecular structure of fluoro-, chloro-, and fluorochloromethanes. For the first time, the accurate ab initio structure is computed for 10 molecules (CF4, CClF3, CCl2F2, CCl3F, CHClF2, CHCl2F, CH2F2, CH2ClF, CH2Cl2, and CCl4) at the coupled cluster level of electronic structure theory including single and double excitations augmented by a perturbational estimate of the effects of connected triple excitations [CCSD(T)] with all electrons being correlated and Gaussian basis sets of at least quadruple-ζ quality. Furthermore, when possible, namely for the molecules CH2F2, CH2Cl2, CH2ClF, CHClF2, and CCl2F2, accurate semi-experimental equilibrium (rSEe) structure has also been determined. This is achieved through a least-squares structural refinement procedure based on the equilibrium rotational constants of all available isotopomers, determined by correcting the experimental ground-state rotational constants with computed ab initio vibration-rotation interaction constants and electronic g-factors. The computed and semi-experimental equilibrium structures are in excellent agreement with each other, but the rSEe structure is generally more accurate, in particular for the CF and CCl bond lengths. The carbon-halogen bond length is discussed within the framework of the ligand close-packing model as a function of the atomic charges. For this purpose, the accurate equilibrium structures of some other molecules with alternative ligands, such as CH3Li, CF3CCH, and CF3CN, are also computed.

  13. Accurate Insertion Loss Measurements of the Juno Patch Array Antennas

    NASA Technical Reports Server (NTRS)

    Chamberlain, Neil; Chen, Jacqueline; Hodges, Richard; Demas, John

    2010-01-01

    This paper describes two independent methods for estimating the insertion loss of patch array antennas that were developed for the Juno Microwave Radiometer instrument. One method is based principally on pattern measurements while the other method is based solely on network analyzer measurements. The methods are accurate to within 0.1 dB for the measured antennas and show good agreement (to within 0.1dB) of separate radiometric measurements.

  14. Accurate method for determining adhesion of cantilever beams

    SciTech Connect

    de Boer, M.P.; Michalske, T.A.

    1999-07-01

    Using surface micromachined samples, we demonstrate the accurate measurement of cantilever beam adhesion by using test structures which are adhered over long attachment lengths. We show that this configuration has a deep energy well, such that a fracture equilibrium is easily reached. When compared to the commonly used method of determining the shortest attached beam, the present method is much less sensitive to variations in surface topography or to details of capillary drying. {copyright} {ital 1999 American Institute of Physics.}

  15. A robust and accurate formulation of molecular and colloidal electrostatics

    NASA Astrophysics Data System (ADS)

    Sun, Qiang; Klaseboer, Evert; Chan, Derek Y. C.

    2016-08-01

    This paper presents a re-formulation of the boundary integral method for the Debye-Hückel model of molecular and colloidal electrostatics that removes the mathematical singularities that have to date been accepted as an intrinsic part of the conventional boundary integral equation method. The essence of the present boundary regularized integral equation formulation consists of subtracting a known solution from the conventional boundary integral method in such a way as to cancel out the singularities associated with the Green's function. This approach better reflects the non-singular physical behavior of the systems on boundaries with the benefits of the following: (i) the surface integrals can be evaluated accurately using quadrature without any need to devise special numerical integration procedures, (ii) being able to use quadratic or spline function surface elements to represent the surface more accurately and the variation of the functions within each element is represented to a consistent level of precision by appropriate interpolation functions, (iii) being able to calculate electric fields, even at boundaries, accurately and directly from the potential without having to solve hypersingular integral equations and this imparts high precision in calculating the Maxwell stress tensor and consequently, intermolecular or colloidal forces, (iv) a reliable way to handle geometric configurations in which different parts of the boundary can be very close together without being affected by numerical instabilities, therefore potentials, fields, and forces between surfaces can be found accurately at surface separations down to near contact, and (v) having the simplicity of a formulation that does not require complex algorithms to handle singularities will result in significant savings in coding effort and in the reduction of opportunities for coding errors. These advantages are illustrated using examples drawn from molecular and colloidal electrostatics.

  16. Water wave model with accurate dispersion and vertical vorticity

    NASA Astrophysics Data System (ADS)

    Bokhove, Onno

    2010-05-01

    Cotter and Bokhove (Journal of Engineering Mathematics 2010) derived a variational water wave model with accurate dispersion and vertical vorticity. In one limit, it leads to Luke's variational principle for potential flow water waves. In the another limit it leads to the depth-averaged shallow water equations including vertical vorticity. Presently, focus will be put on the Hamiltonian formulation of the variational model and its boundary conditions.

  17. Strategy Guideline: Accurate Heating and Cooling Load Calculations

    SciTech Connect

    Burdick, A.

    2011-06-01

    This guide presents the key criteria required to create accurate heating and cooling load calculations and offers examples of the implications when inaccurate adjustments are applied to the HVAC design process. The guide shows, through realistic examples, how various defaults and arbitrary safety factors can lead to significant increases in the load estimate. Emphasis is placed on the risks incurred from inaccurate adjustments or ignoring critical inputs of the load calculation.

  18. Accurate or Assumed: Visual Learning in Children with ASD

    ERIC Educational Resources Information Center

    Trembath, David; Vivanti, Giacomo; Iacono, Teresa; Dissanayake, Cheryl

    2015-01-01

    Children with autism spectrum disorder (ASD) are often described as visual learners. We tested this assumption in an experiment in which 25 children with ASD, 19 children with global developmental delay (GDD), and 17 typically developing (TD) children were presented a series of videos via an eye tracker in which an actor instructed them to…

  19. Using GPS To Teach More Than Accurate Positions.

    ERIC Educational Resources Information Center

    Johnson, Marie C.; Guth, Peter L.

    2002-01-01

    Undergraduate science majors need practice in critical thinking, quantitative analysis, and judging whether their calculated answers are physically reasonable. Develops exercises using handheld Global Positioning System (GPS) receivers. Reinforces students' abilities to think quantitatively, make realistic "back of the envelope" assumptions, and…

  20. Accurate thermoelastic tensor and acoustic velocities of NaCl

    NASA Astrophysics Data System (ADS)

    Marcondes, Michel L.; Shukla, Gaurav; da Silveira, Pedro; Wentzcovitch, Renata M.

    2015-12-01

    Despite the importance of thermoelastic properties of minerals in geology and geophysics, their measurement at high pressures and temperatures are still challenging. Thus, ab initio calculations are an essential tool for predicting these properties at extreme conditions. Owing to the approximate description of the exchange-correlation energy, approximations used in calculations of vibrational effects, and numerical/methodological approximations, these methods produce systematic deviations. Hybrid schemes combining experimental data and theoretical results have emerged as a way to reconcile available information and offer more reliable predictions at experimentally inaccessible thermodynamics conditions. Here we introduce a method to improve the calculated thermoelastic tensor by using highly accurate thermal equation of state (EoS). The corrective scheme is general, applicable to crystalline solids with any symmetry, and can produce accurate results at conditions where experimental data may not exist. We apply it to rock-salt-type NaCl, a material whose structural properties have been challenging to describe accurately by standard ab initio methods and whose acoustic/seismic properties are important for the gas and oil industry.

  1. Accurate and occlusion-robust multi-view stereo

    NASA Astrophysics Data System (ADS)

    Zhu, Zhaokun; Stamatopoulos, Christos; Fraser, Clive S.

    2015-11-01

    This paper proposes an accurate multi-view stereo method for image-based 3D reconstruction that features robustness in the presence of occlusions. The new method offers improvements in dealing with two fundamental image matching problems. The first concerns the selection of the support window model, while the second centers upon accurate visibility estimation for each pixel. The support window model is based on an approximate 3D support plane described by a depth and two per-pixel depth offsets. For the visibility estimation, the multi-view constraint is initially relaxed by generating separate support plane maps for each support image using a modified PatchMatch algorithm. Then the most likely visible support image, which represents the minimum visibility of each pixel, is extracted via a discrete Markov Random Field model and it is further augmented by parameter clustering. Once the visibility is estimated, multi-view optimization taking into account all redundant observations is conducted to achieve optimal accuracy in the 3D surface generation for both depth and surface normal estimates. Finally, multi-view consistency is utilized to eliminate any remaining observational outliers. The proposed method is experimentally evaluated using well-known Middlebury datasets, and results obtained demonstrate that it is amongst the most accurate of the methods thus far reported via the Middlebury MVS website. Moreover, the new method exhibits a high completeness rate.

  2. Method and apparatus for accurately manipulating an object during microelectrophoresis

    DOEpatents

    Parvin, Bahram A.; Maestre, Marcos F.; Fish, Richard H.; Johnston, William E.

    1997-01-01

    An apparatus using electrophoresis provides accurate manipulation of an object on a microscope stage for further manipulations add reactions. The present invention also provides an inexpensive and easily accessible means to move an object without damage to the object. A plurality of electrodes are coupled to the stage in an array whereby the electrode array allows for distinct manipulations of the electric field for accurate manipulations of the object. There is an electrode array control coupled to the plurality of electrodes for manipulating the electric field. In an alternative embodiment, a chamber is provided on the stage to hold the object. The plurality of electrodes are positioned in the chamber, and the chamber is filled with fluid. The system can be automated using visual servoing, which manipulates the control parameters, i.e., x, y stage, applying the field, etc., after extracting the significant features directly from image data. Visual servoing includes an imaging device and computer system to determine the location of the object. A second stage having a plurality of tubes positioned on top of the second stage, can be accurately positioned by visual servoing so that one end of one of the plurality of tubes surrounds at least part of the object on the first stage.

  3. Method and apparatus for accurately manipulating an object during microelectrophoresis

    DOEpatents

    Parvin, B.A.; Maestre, M.F.; Fish, R.H.; Johnston, W.E.

    1997-09-23

    An apparatus using electrophoresis provides accurate manipulation of an object on a microscope stage for further manipulations and reactions. The present invention also provides an inexpensive and easily accessible means to move an object without damage to the object. A plurality of electrodes are coupled to the stage in an array whereby the electrode array allows for distinct manipulations of the electric field for accurate manipulations of the object. There is an electrode array control coupled to the plurality of electrodes for manipulating the electric field. In an alternative embodiment, a chamber is provided on the stage to hold the object. The plurality of electrodes are positioned in the chamber, and the chamber is filled with fluid. The system can be automated using visual servoing, which manipulates the control parameters, i.e., x, y stage, applying the field, etc., after extracting the significant features directly from image data. Visual servoing includes an imaging device and computer system to determine the location of the object. A second stage having a plurality of tubes positioned on top of the second stage, can be accurately positioned by visual servoing so that one end of one of the plurality of tubes surrounds at least part of the object on the first stage. 11 figs.

  4. Accurate pose estimation using single marker single camera calibration system

    NASA Astrophysics Data System (ADS)

    Pati, Sarthak; Erat, Okan; Wang, Lejing; Weidert, Simon; Euler, Ekkehard; Navab, Nassir; Fallavollita, Pascal

    2013-03-01

    Visual marker based tracking is one of the most widely used tracking techniques in Augmented Reality (AR) applications. Generally, multiple square markers are needed to perform robust and accurate tracking. Various marker based methods for calibrating relative marker poses have already been proposed. However, the calibration accuracy of these methods relies on the order of the image sequence and pre-evaluation of pose-estimation errors, making the method offline. Several studies have shown that the accuracy of pose estimation for an individual square marker depends on camera distance and viewing angle. We propose a method to accurately model the error in the estimated pose and translation of a camera using a single marker via an online method based on the Scaled Unscented Transform (SUT). Thus, the pose estimation for each marker can be estimated with highly accurate calibration results independent of the order of image sequences compared to cases when this knowledge is not used. This removes the need for having multiple markers and an offline estimation system to calculate camera pose in an AR application.

  5. Accurate projector calibration method by using an optical coaxial camera.

    PubMed

    Huang, Shujun; Xie, Lili; Wang, Zhangying; Zhang, Zonghua; Gao, Feng; Jiang, Xiangqian

    2015-02-01

    Digital light processing (DLP) projectors have been widely utilized to project digital structured-light patterns in 3D imaging systems. In order to obtain accurate 3D shape data, it is important to calibrate DLP projectors to obtain the internal parameters. The existing projector calibration methods have complicated procedures or low accuracy of the obtained parameters. This paper presents a novel method to accurately calibrate a DLP projector by using an optical coaxial camera. The optical coaxial geometry is realized by a plate beam splitter, so the DLP projector can be treated as a true inverse camera. A plate having discrete markers on the surface is used to calibrate the projector. The corresponding projector pixel coordinate of each marker on the plate is determined by projecting vertical and horizontal sinusoidal fringe patterns on the plate surface and calculating the absolute phase. The internal parameters of the DLP projector are obtained by the corresponding point pair between the projector pixel coordinate and the world coordinate of discrete markers. Experimental results show that the proposed method can accurately calibrate the internal parameters of a DLP projector. PMID:25967789

  6. Can blind persons accurately assess body size from the voice?

    PubMed

    Pisanski, Katarzyna; Oleszkiewicz, Anna; Sorokowska, Agnieszka

    2016-04-01

    Vocal tract resonances provide reliable information about a speaker's body size that human listeners use for biosocial judgements as well as speech recognition. Although humans can accurately assess men's relative body size from the voice alone, how this ability is acquired remains unknown. In this study, we test the prediction that accurate voice-based size estimation is possible without prior audiovisual experience linking low frequencies to large bodies. Ninety-one healthy congenitally or early blind, late blind and sighted adults (aged 20-65) participated in the study. On the basis of vowel sounds alone, participants assessed the relative body sizes of male pairs of varying heights. Accuracy of voice-based body size assessments significantly exceeded chance and did not differ among participants who were sighted, or congenitally blind or who had lost their sight later in life. Accuracy increased significantly with relative differences in physical height between men, suggesting that both blind and sighted participants used reliable vocal cues to size (i.e. vocal tract resonances). Our findings demonstrate that prior visual experience is not necessary for accurate body size estimation. This capacity, integral to both nonverbal communication and speech perception, may be present at birth or may generalize from broader cross-modal correspondences. PMID:27095264

  7. Accurate forced-choice recognition without awareness of memory retrieval.

    PubMed

    Voss, Joel L; Baym, Carol L; Paller, Ken A

    2008-06-01

    Recognition confidence and the explicit awareness of memory retrieval commonly accompany accurate responding in recognition tests. Memory performance in recognition tests is widely assumed to measure explicit memory, but the generality of this assumption is questionable. Indeed, whether recognition in nonhumans is always supported by explicit memory is highly controversial. Here we identified circumstances wherein highly accurate recognition was unaccompanied by hallmark features of explicit memory. When memory for kaleidoscopes was tested using a two-alternative forced-choice recognition test with similar foils, recognition was enhanced by an attentional manipulation at encoding known to degrade explicit memory. Moreover, explicit recognition was most accurate when the awareness of retrieval was absent. These dissociations between accuracy and phenomenological features of explicit memory are consistent with the notion that correct responding resulted from experience-dependent enhancements of perceptual fluency with specific stimuli--the putative mechanism for perceptual priming effects in implicit memory tests. This mechanism may contribute to recognition performance in a variety of frequently-employed testing circumstances. Our results thus argue for a novel view of recognition, in that analyses of its neurocognitive foundations must take into account the potential for both (1) recognition mechanisms allied with implicit memory and (2) recognition mechanisms allied with explicit memory. PMID:18519546

  8. Differential equation based method for accurate approximations in optimization

    NASA Technical Reports Server (NTRS)

    Pritchard, Jocelyn I.; Adelman, Howard M.

    1990-01-01

    This paper describes a method to efficiently and accurately approximate the effect of design changes on structural response. The key to this new method is to interpret sensitivity equations as differential equations that may be solved explicitly for closed form approximations, hence, the method is denoted the Differential Equation Based (DEB) method. Approximations were developed for vibration frequencies, mode shapes and static displacements. The DEB approximation method was applied to a cantilever beam and results compared with the commonly-used linear Taylor series approximations and exact solutions. The test calculations involved perturbing the height, width, cross-sectional area, tip mass, and bending inertia of the beam. The DEB method proved to be very accurate, and in msot cases, was more accurate than the linear Taylor series approximation. The method is applicable to simultaneous perturbation of several design variables. Also, the approximations may be used to calculate other system response quantities. For example, the approximations for displacement are used to approximate bending stresses.

  9. Accurate thermochemistry for medium-sized and large molecules

    SciTech Connect

    Raghavachari, K.; Stefanov, B.B.; Curtiss, L.A.

    1997-12-31

    Accurate techniques such as Gaussian-2 (G2) theory have been proposed in recent years to evaluate the thermochemistry of small molecules from first-principles. However, as the molecules get larger, the errors in G2 theory and similar approaches tend to accumulate. For example, the computed heats of formation of benzene and naphthalene with G2 and G2(MP2) theories, respectively, have errors of 3.9 and 7.2 kcal/mol. In this work, we explore strategies for computing accurate heats of formation for medium-sized and large molecules. In our first scheme, G2 theory is combined with isodesmic bond separation reaction energies to yield accurate thermochemistry for larger molecules. For a test set of 40 molecules composed of H, C, O, and N, our method yields enthalpies of formation, {Delta}H{sub f}{sup 0}(298 K), with a mean absolute deviation from experiment of only 0.5 kcal/mol. This is an improvement of a factor of three over the deviation of 1.5 kcal/mol seen in standard G2 theory.

  10. Accurately measuring volcanic plume velocity with multiple UV spectrometers

    USGS Publications Warehouse

    Williams-Jones, G.; Horton, K.A.; Elias, T.; Garbeil, H.; Mouginis-Mark, P. J.; Sutton, A.J.; Harris, A.J.L.

    2006-01-01

    A fundamental problem with all ground-based remotely sensed measurements of volcanic gas flux is the difficulty in accurately measuring the velocity of the gas plume. Since a representative wind speed and direction are used as proxies for the actual plume velocity, there can be considerable uncertainty in reported gas flux values. Here we present a method that uses at least two time-synchronized simultaneously recording UV spectrometers (FLYSPECs) placed a known distance apart. By analyzing the time varying structure of SO2 concentration signals at each instrument, the plume velocity can accurately be determined. Experiments were conducted on Ki??lauea (USA) and Masaya (Nicaragua) volcanoes in March and August 2003 at plume velocities between 1 and 10 m s-1. Concurrent ground-based anemometer measurements differed from FLYSPEC-measured plume speeds by up to 320%. This multi-spectrometer method allows for the accurate remote measurement of plume velocity and can therefore greatly improve the precision of volcanic or industrial gas flux measurements. ?? Springer-Verlag 2006.

  11. Can clinicians accurately assess esophageal dilation without fluoroscopy?

    PubMed

    Bailey, A D; Goldner, F

    1990-01-01

    This study questioned whether clinicians could determine the success of esophageal dilation accurately without the aid of fluoroscopy. Twenty patients were enrolled with the diagnosis of distal esophageal stenosis, including benign peptic stricture (17), Schatski's ring (2), and squamous cell carcinoma of the esophagus (1). Dilation attempts using only Maloney dilators were monitored fluoroscopically by the principle investigator, the physician and patient being unaware of the findings. Physicians then predicted whether or not their dilations were successful, and they examined various features to determine their usefulness in predicting successful dilation. They were able to predict successful dilation accurately in 97% of the cases studied; however, their predictions of unsuccessful dilation were correct only 60% of the time. Features helpful in predicting passage included easy passage of the dilator (98%) and the patient feeling the dilator in the stomach (95%). Excessive resistance suggesting unsuccessful passage was an unreliable feature and was often due to the dilator curling in the stomach. When Maloney dilators are used to dilate simple distal strictures, if the physician predicts successful passage, he is reliably accurate without the use of fluoroscopy; however, if unsuccessful passage is suspected, fluoroscopy must be used for confirmation. PMID:2210278

  12. Efficient and accurate computation of generalized singular-value decompositions

    NASA Astrophysics Data System (ADS)

    Drmac, Zlatko

    2001-11-01

    We present a new family of algorithms for accurate floating--point computation of the singular value decomposition (SVD) of various forms of products (quotients) of two or three matrices. The main goal of such an algorithm is to compute all singular values to high relative accuracy. This means that we are seeking guaranteed number of accurate digits even in the smallest singular values. We also want to achieve computational efficiency, while maintaining high accuracy. To illustrate, consider the SVD of the product A=BTSC. The new algorithm uses certain preconditioning (based on diagonal scalings, the LU and QR factorizations) to replace A with A'=(B')TS'C', where A and A' have the same singular values and the matrix A' is computed explicitly. Theoretical analysis and numerical evidence show that, in the case of full rank B, C, S, the accuracy of the new algorithm is unaffected by replacing B, S, C with, respectively, D1B, D2SD3, D4C, where Di, i=1,...,4 are arbitrary diagonal matrices. As an application, the paper proposes new accurate algorithms for computing the (H,K)-SVD and (H1,K)-SVD of S.

  13. Accurate thermoelastic tensor and acoustic velocities of NaCl

    SciTech Connect

    Marcondes, Michel L.; Shukla, Gaurav; Silveira, Pedro da; Wentzcovitch, Renata M.

    2015-12-15

    Despite the importance of thermoelastic properties of minerals in geology and geophysics, their measurement at high pressures and temperatures are still challenging. Thus, ab initio calculations are an essential tool for predicting these properties at extreme conditions. Owing to the approximate description of the exchange-correlation energy, approximations used in calculations of vibrational effects, and numerical/methodological approximations, these methods produce systematic deviations. Hybrid schemes combining experimental data and theoretical results have emerged as a way to reconcile available information and offer more reliable predictions at experimentally inaccessible thermodynamics conditions. Here we introduce a method to improve the calculated thermoelastic tensor by using highly accurate thermal equation of state (EoS). The corrective scheme is general, applicable to crystalline solids with any symmetry, and can produce accurate results at conditions where experimental data may not exist. We apply it to rock-salt-type NaCl, a material whose structural properties have been challenging to describe accurately by standard ab initio methods and whose acoustic/seismic properties are important for the gas and oil industry.

  14. A unique approach to accurately measure thickness in thick multilayers.

    PubMed

    Shi, Bing; Hiller, Jon M; Liu, Yuzi; Liu, Chian; Qian, Jun; Gades, Lisa; Wieczorek, Michael J; Marander, Albert T; Maser, Jorg; Assoufid, Lahsen

    2012-05-01

    X-ray optics called multilayer Laue lenses (MLLs) provide a promising path to focusing hard X-rays with high focusing efficiency at a resolution between 5 nm and 20 nm. MLLs consist of thousands of depth-graded thin layers. The thickness of each layer obeys the linear zone plate law. X-ray beamline tests have been performed on magnetron sputter-deposited WSi(2)/Si MLLs at the Advanced Photon Source/Center for Nanoscale Materials 26-ID nanoprobe beamline. However, it is still very challenging to accurately grow each layer at the designed thickness during deposition; errors introduced during thickness measurements of thousands of layers lead to inaccurate MLL structures. Here, a new metrology approach that can accurately measure thickness by introducing regular marks on the cross section of thousands of layers using a focused ion beam is reported. This new measurement method is compared with a previous method. More accurate results are obtained using the new measurement approach. PMID:22514179

  15. Global temperatures and the global warming ``debate''

    NASA Astrophysics Data System (ADS)

    Aubrecht, Gordon

    2009-04-01

    Many ordinary citizens listen to pronouncements on talk radio casting doubt on anthropogenic global warming. Some op-ed columnists likewise cast doubts, and are read by credulous citizens. For example, on 8 March 2009, the Boston Globe published a column by Jeff Jacoby, ``Where's global warming?'' According to Jacoby, ``But it isn't such hints of a planetary warming trend that have been piling up in profusion lately. Just the opposite.'' He goes on to write, ``the science of climate change is not nearly as important as the religion of climate change,'' and blamed Al Gore for getting his mistaken views accepted. George Will at the Washington Post also expressed denial. As a result, 44% of U.S. voters, according to the January 19 2009 Rasmussen Report, blame long-term planetary trends for global warming, not human beings. Is there global cooling, as skeptics claim? We examine the temperature record.

  16. Global sea level linked to global temperature

    PubMed Central

    Vermeer, Martin; Rahmstorf, Stefan

    2009-01-01

    We propose a simple relationship linking global sea-level variations on time scales of decades to centuries to global mean temperature. This relationship is tested on synthetic data from a global climate model for the past millennium and the next century. When applied to observed data of sea level and temperature for 1880–2000, and taking into account known anthropogenic hydrologic contributions to sea level, the correlation is >0.99, explaining 98% of the variance. For future global temperature scenarios of the Intergovernmental Panel on Climate Change's Fourth Assessment Report, the relationship projects a sea-level rise ranging from 75 to 190 cm for the period 1990–2100. PMID:19995972

  17. Global Health and the Global Economic Crisis

    PubMed Central

    Gill, Stephen; Bakker, Isabella

    2011-01-01

    Although the resources and knowledge for achieving improved global health exist, a new, critical paradigm on health as an aspect of human development, human security, and human rights is needed. Such a shift is required to sufficiently modify and credibly reduce the present dominance of perverse market forces on global health. New scientific discoveries can make wide-ranging contributions to improved health; however, improved global health depends on achieving greater social justice, economic redistribution, and enhanced democratization of production, caring social institutions for essential health care, education, and other public goods. As with the quest for an HIV vaccine, the challenge of improved global health requires an ambitious multidisciplinary research program. PMID:21330597

  18. Global social identity and global cooperation.

    PubMed

    Buchan, Nancy R; Brewer, Marilynn B; Grimalda, Gianluca; Wilson, Rick K; Fatas, Enrique; Foddy, Margaret

    2011-06-01

    This research examined the question of whether the psychology of social identity can motivate cooperation in the context of a global collective. Our data came from a multinational study of choice behavior in a multilevel public-goods dilemma conducted among samples drawn from the general populations of the United States, Italy, Russia, Argentina, South Africa, and Iran. Results demonstrate that an inclusive social identification with the world community is a meaningful psychological construct that plays a role in motivating cooperation that transcends parochial interests. Self-reported identification with the world as a whole predicts behavioral contributions to a global public good beyond what is predicted from expectations about what other people are likely to contribute. Furthermore, global social identification is conceptually distinct from general attitudes about global issues, and has unique effects on cooperative behavior. PMID:21586763

  19. Measuring solar reflectance Part I: Defining a metric that accurately predicts solar heat gain

    SciTech Connect

    Levinson, Ronnen; Akbari, Hashem; Berdahl, Paul

    2010-05-14

    Solar reflectance can vary with the spectral and angular distributions of incident sunlight, which in turn depend on surface orientation, solar position and atmospheric conditions. A widely used solar reflectance metric based on the ASTM Standard E891 beam-normal solar spectral irradiance underestimates the solar heat gain of a spectrally selective 'cool colored' surface because this irradiance contains a greater fraction of near-infrared light than typically found in ordinary (unconcentrated) global sunlight. At mainland U.S. latitudes, this metric RE891BN can underestimate the annual peak solar heat gain of a typical roof or pavement (slope {le} 5:12 [23{sup o}]) by as much as 89 W m{sup -2}, and underestimate its peak surface temperature by up to 5 K. Using R{sub E891BN} to characterize roofs in a building energy simulation can exaggerate the economic value N of annual cool-roof net energy savings by as much as 23%. We define clear-sky air mass one global horizontal ('AM1GH') solar reflectance R{sub g,0}, a simple and easily measured property that more accurately predicts solar heat gain. R{sub g,0} predicts the annual peak solar heat gain of a roof or pavement to within 2 W m{sup -2}, and overestimates N by no more than 3%. R{sub g,0} is well suited to rating the solar reflectances of roofs, pavements and walls. We show in Part II that R{sub g,0} can be easily and accurately measured with a pyranometer, a solar spectrophotometer or version 6 of the Solar Spectrum Reflectometer.

  20. Measuring solar reflectance - Part I: Defining a metric that accurately predicts solar heat gain

    SciTech Connect

    Levinson, Ronnen; Akbari, Hashem; Berdahl, Paul

    2010-09-15

    Solar reflectance can vary with the spectral and angular distributions of incident sunlight, which in turn depend on surface orientation, solar position and atmospheric conditions. A widely used solar reflectance metric based on the ASTM Standard E891 beam-normal solar spectral irradiance underestimates the solar heat gain of a spectrally selective ''cool colored'' surface because this irradiance contains a greater fraction of near-infrared light than typically found in ordinary (unconcentrated) global sunlight. At mainland US latitudes, this metric R{sub E891BN} can underestimate the annual peak solar heat gain of a typical roof or pavement (slope {<=} 5:12 [23 ]) by as much as 89 W m{sup -2}, and underestimate its peak surface temperature by up to 5 K. Using R{sub E891BN} to characterize roofs in a building energy simulation can exaggerate the economic value N of annual cool roof net energy savings by as much as 23%. We define clear sky air mass one global horizontal (''AM1GH'') solar reflectance R{sub g,0}, a simple and easily measured property that more accurately predicts solar heat gain. R{sub g,0} predicts the annual peak solar heat gain of a roof or pavement to within 2 W m{sup -2}, and overestimates N by no more than 3%. R{sub g,0} is well suited to rating the solar reflectances of roofs, pavements and walls. We show in Part II that R{sub g,0} can be easily and accurately measured with a pyranometer, a solar spectrophotometer or version 6 of the Solar Spectrum Reflectometer. (author)

  1. Beyond global warming: Ecology and global change

    SciTech Connect

    Vitousek, P.M. )

    1994-10-01

    While ecologists involved in management or policy often are advised to learn to deal with uncertainty, some components of global environmental change are certainly occurring and are certainly human-caused. All have important ecological consequences. Well-documented global changes include: Increasing concentrations of carbon dioxide in the atmosphere; alterations in the biogeochemistry of the global nitrogen cycle; and ongoing land use/land cover change. Human activity - now primarily fossil fuel combustion - has increased carbon dioxide concentrations from [approximately] 280 to 355 [mu]L/L since 1800 and is likely to have climatic consequences and direct effects on biota in all terrestrial ecosystems. The global nitrogen cycle has been altered so that more nitrogen is fixed annually by humanity than by all natural pathways combined. Altering atmospheric chemistry and aquatic ecosystems, contributes to eutrophication of the biosphere, and has substantial regional effects on biological diversity. Finally, human land use/land cover change has transformed one-third to one-half of Earth's ice-free surface, representing the most important component of global change now. Any clear dichotomy between pristine ecosystems and human-altered areas that may have existed in the past has vanished, and ecological research should account for this reality. Certain components of global environmental change are the primary causes of anticipated changes in climate, and of ongoing losses of biological diversity. They are caused by the extraordinary growth in size and resource use of the human population. On a broad scale, there is little uncertainty about any of these components of change or their causes. However, much of the public believes the causes of global change to be uncertain and contentious. By speaking out effectively,the focus of public discussion towards what can and should be done about global environmental change can be shifted. 135 refs., 13 figs., 1 tab.

  2. Global perspectives: A new global ethic, a new global partnership

    SciTech Connect

    Brundtland, G.H.

    1990-06-01

    In her keynote address at the opening plenary session of the Globe '90 Conference held in Vancouver in March, Mrs. Brundtland called for a new global partnership of government, industry, producers and consumers to meet present and future environmental challenges. This partnership would require help to developing countries to help free them from their handicaps of debt, overpopulation and poverty; that improvements made to the environment would not be offset by ecological damage in other areas. She was encouraged that the policy of sustainable development has been widely adapted as the only viable strategy for global change.

  3. MapSplice: Accurate mapping of RNA-seq reads for splice junction discovery

    PubMed Central

    Wang, Kai; Singh, Darshan; Zeng, Zheng; Coleman, Stephen J.; Huang, Yan; Savich, Gleb L.; He, Xiaping; Mieczkowski, Piotr; Grimm, Sara A.; Perou, Charles M.; MacLeod, James N.; Chiang, Derek Y.; Prins, Jan F.; Liu, Jinze

    2010-01-01

    The accurate mapping of reads that span splice junctions is a critical component of all analytic techniques that work with RNA-seq data. We introduce a second generation splice detection algorithm, MapSplice, whose focus is high sensitivity and specificity in the detection of splices as well as CPU and memory efficiency. MapSplice can be applied to both short (<75 bp) and long reads (≥75 bp). MapSplice is not dependent on splice site features or intron length, consequently it can detect novel canonical as well as non-canonical splices. MapSplice leverages the quality and diversity of read alignments of a given splice to increase accuracy. We demonstrate that MapSplice achieves higher sensitivity and specificity than TopHat and SpliceMap on a set of simulated RNA-seq data. Experimental studies also support the accuracy of the algorithm. Splice junctions derived from eight breast cancer RNA-seq datasets recapitulated the extensiveness of alternative splicing on a global level as well as the differences between molecular subtypes of breast cancer. These combined results indicate that MapSplice is a highly accurate algorithm for the alignment of RNA-seq reads to splice junctions. Software download URL: http://www.netlab.uky.edu/p/bioinfo/MapSplice. PMID:20802226

  4. MapSplice: accurate mapping of RNA-seq reads for splice junction discovery.

    PubMed

    Wang, Kai; Singh, Darshan; Zeng, Zheng; Coleman, Stephen J; Huang, Yan; Savich, Gleb L; He, Xiaping; Mieczkowski, Piotr; Grimm, Sara A; Perou, Charles M; MacLeod, James N; Chiang, Derek Y; Prins, Jan F; Liu, Jinze

    2010-10-01

    The accurate mapping of reads that span splice junctions is a critical component of all analytic techniques that work with RNA-seq data. We introduce a second generation splice detection algorithm, MapSplice, whose focus is high sensitivity and specificity in the detection of splices as well as CPU and memory efficiency. MapSplice can be applied to both short (<75 bp) and long reads (≥ 75 bp). MapSplice is not dependent on splice site features or intron length, consequently it can detect novel canonical as well as non-canonical splices. MapSplice leverages the quality and diversity of read alignments of a given splice to increase accuracy. We demonstrate that MapSplice achieves higher sensitivity and specificity than TopHat and SpliceMap on a set of simulated RNA-seq data. Experimental studies also support the accuracy of the algorithm. Splice junctions derived from eight breast cancer RNA-seq datasets recapitulated the extensiveness of alternative splicing on a global level as well as the differences between molecular subtypes of breast cancer. These combined results indicate that MapSplice is a highly accurate algorithm for the alignment of RNA-seq reads to splice junctions. Software download URL: http://www.netlab.uky.edu/p/bioinfo/MapSplice. PMID:20802226

  5. Identification of accurate nonlinear rainfall-runoff models with unique parameters

    NASA Astrophysics Data System (ADS)

    Schoups, G.; Vrugt, J. A.; Fenicia, F.; van de Giesen, N.

    2009-04-01

    We propose a strategy to identify models with unique parameters that yield accurate streamflow predictions, given a time-series of rainfall inputs. The procedure consists of five general steps. First, an a priori range of model structures is specified based on prior general and site-specific hydrologic knowledge. To this end, we rely on a flexible model code that allows a specification of a wide range of model structures, from simple to complex. Second, using global optimization each model structure is calibrated to a record of rainfall-runoff data, yielding optimal parameter values for each model structure. Third, accuracy of each model structure is determined by estimating model prediction errors using independent validation and statistical theory. Fourth, parameter identifiability of each calibrated model structure is estimated by means of Monte Carlo Markov Chain simulation. Finally, an assessment is made about each model structure in terms of its accuracy of mimicking rainfall-runoff processes (step 3), and the uniqueness of its parameters (step 4). The procedure results in the identification of the most complex and accurate model supported by the data, without causing parameter equifinality. As such, it provides insight into the information content of the data for identifying nonlinear rainfall-runoff models. We illustrate the method using rainfall-runoff data records from several MOPEX basins in the US.

  6. Accurate Vehicle Location System Using RFID, an Internet of Things Approach

    PubMed Central

    Prinsloo, Jaco; Malekian, Reza

    2016-01-01

    Modern infrastructure, such as dense urban areas and underground tunnels, can effectively block all GPS signals, which implies that effective position triangulation will not be achieved. The main problem that is addressed in this project is the design and implementation of an accurate vehicle location system using radio-frequency identification (RFID) technology in combination with GPS and the Global system for Mobile communication (GSM) technology, in order to provide a solution to the limitation discussed above. In essence, autonomous vehicle tracking will be facilitated with the use of RFID technology where GPS signals are non-existent. The design of the system and the results are reflected in this paper. An extensive literature study was done on the field known as the Internet of Things, as well as various topics that covered the integration of independent technology in order to address a specific challenge. The proposed system is then designed and implemented. An RFID transponder was successfully designed and a read range of approximately 31 cm was obtained in the low frequency communication range (125 kHz to 134 kHz). The proposed system was designed, implemented, and field tested and it was found that a vehicle could be accurately located and tracked. It is also found that the antenna size of both the RFID reader unit and RFID transponder plays a critical role in the maximum communication range that can be achieved. PMID:27271638

  7. Accurate Vehicle Location System Using RFID, an Internet of Things Approach.

    PubMed

    Prinsloo, Jaco; Malekian, Reza

    2016-01-01

    Modern infrastructure, such as dense urban areas and underground tunnels, can effectively block all GPS signals, which implies that effective position triangulation will not be achieved. The main problem that is addressed in this project is the design and implementation of an accurate vehicle location system using radio-frequency identification (RFID) technology in combination with GPS and the Global system for Mobile communication (GSM) technology, in order to provide a solution to the limitation discussed above. In essence, autonomous vehicle tracking will be facilitated with the use of RFID technology where GPS signals are non-existent. The design of the system and the results are reflected in this paper. An extensive literature study was done on the field known as the Internet of Things, as well as various topics that covered the integration of independent technology in order to address a specific challenge. The proposed system is then designed and implemented. An RFID transponder was successfully designed and a read range of approximately 31 cm was obtained in the low frequency communication range (125 kHz to 134 kHz). The proposed system was designed, implemented, and field tested and it was found that a vehicle could be accurately located and tracked. It is also found that the antenna size of both the RFID reader unit and RFID transponder plays a critical role in the maximum communication range that can be achieved. PMID:27271638

  8. Fully Automated Generation of Accurate Digital Surface Models with Sub-Meter Resolution from Satellite Imagery

    NASA Astrophysics Data System (ADS)

    Wohlfeil, J.; Hirschmüller, H.; Piltz, B.; Börner, A.; Suppa, M.

    2012-07-01

    Modern pixel-wise image matching algorithms like Semi-Global Matching (SGM) are able to compute high resolution digital surface models from airborne and spaceborne stereo imagery. Although image matching itself can be performed automatically, there are prerequisites, like high geometric accuracy, which are essential for ensuring the high quality of resulting surface models. Especially for line cameras, these prerequisites currently require laborious manual interaction using standard tools, which is a growing problem due to continually increasing demand for such surface models. The tedious work includes partly or fully manual selection of tie- and/or ground control points for ensuring the required accuracy of the relative orientation of images for stereo matching. It also includes masking of large water areas that seriously reduce the quality of the results. Furthermore, a good estimate of the depth range is required, since accurate estimates can seriously reduce the processing time for stereo matching. In this paper an approach is presented that allows performing all these steps fully automated. It includes very robust and precise tie point selection, enabling the accurate calculation of the images' relative orientation via bundle adjustment. It is also shown how water masking and elevation range estimation can be performed automatically on the base of freely available SRTM data. Extensive tests with a large number of different satellite images from QuickBird and WorldView are presented as proof of the robustness and reliability of the proposed method.

  9. Accurate Mobile Urban Mapping via Digital Map-Based SLAM †.

    PubMed

    Roh, Hyunchul; Jeong, Jinyong; Cho, Younggun; Kim, Ayoung

    2016-01-01

    This paper presents accurate urban map generation using digital map-based Simultaneous Localization and Mapping (SLAM). Throughout this work, our main objective is generating a 3D and lane map aiming for sub-meter accuracy. In conventional mapping approaches, achieving extremely high accuracy was performed by either (i) exploiting costly airborne sensors or (ii) surveying with a static mapping system in a stationary platform. Mobile scanning systems recently have gathered popularity but are mostly limited by the availability of the Global Positioning System (GPS). We focus on the fact that the availability of GPS and urban structures are both sporadic but complementary. By modeling both GPS and digital map data as measurements and integrating them with other sensor measurements, we leverage SLAM for an accurate mobile mapping system. Our proposed algorithm generates an efficient graph SLAM and achieves a framework running in real-time and targeting sub-meter accuracy with a mobile platform. Integrated with the SLAM framework, we implement a motion-adaptive model for the Inverse Perspective Mapping (IPM). Using motion estimation derived from SLAM, the experimental results show that the proposed approaches provide stable bird's-eye view images, even with significant motion during the drive. Our real-time map generation framework is validated via a long-distance urban test and evaluated at randomly sampled points using Real-Time Kinematic (RTK)-GPS. PMID:27548175

  10. Joint iris boundary detection and fit: a real-time method for accurate pupil tracking.

    PubMed

    Barbosa, Marconi; James, Andrew C

    2014-08-01

    A range of applications in visual science rely on accurate tracking of the human pupil's movement and contraction in response to light. While the literature for independent contour detection and fitting of the iris-pupil boundary is vast, a joint approach, in which it is assumed that the pupil has a given geometric shape has been largely overlooked. We present here a global method for simultaneously finding and fitting of an elliptic or circular contour against a dark interior, which produces consistently accurate results even under non-ideal recording conditions, such as reflections near and over the boundary, droopy eye lids, or the sudden formation of tears. The specific form of the proposed optimization problem allows us to write down closed analytic formulae for the gradient and the Hessian of the objective function. Moreover, both the objective function and its derivatives can be cast into vectorized form, making the proposed algorithm significantly faster than its closest relative in the literature. We compare methods in multiple ways, both analytically and numerically, using real iris images as well as idealizations of the iris for which the ground truth boundary is precisely known. The method proposed here is illustrated under challenging recording conditions and it is shown to be robust. PMID:25136477

  11. Accurate protein structure modeling using sparse NMR data and homologous structure information

    PubMed Central

    Thompson, James M.; Sgourakis, Nikolaos G.; Liu, Gaohua; Rossi, Paolo; Tang, Yuefeng; Mills, Jeffrey L.; Szyperski, Thomas; Montelione, Gaetano T.; Baker, David

    2012-01-01

    While information from homologous structures plays a central role in X-ray structure determination by molecular replacement, such information is rarely used in NMR structure determination because it can be incorrect, both locally and globally, when evolutionary relationships are inferred incorrectly or there has been considerable evolutionary structural divergence. Here we describe a method that allows robust modeling of protein structures of up to 225 residues by combining , 13C, and 15N backbone and 13Cβ chemical shift data, distance restraints derived from homologous structures, and a physically realistic all-atom energy function. Accurate models are distinguished from inaccurate models generated using incorrect sequence alignments by requiring that (i) the all-atom energies of models generated using the restraints are lower than models generated in unrestrained calculations and (ii) the low-energy structures converge to within 2.0 Å backbone rmsd over 75% of the protein. Benchmark calculations on known structures and blind targets show that the method can accurately model protein structures, even with very remote homology information, to a backbone rmsd of 1.2–1.9 Å relative to the conventional determined NMR ensembles and of 0.9–1.6 Å relative to X-ray structures for well-defined regions of the protein structures. This approach facilitates the accurate modeling of protein structures using backbone chemical shift data without need for side-chain resonance assignments and extensive analysis of NOESY cross-peak assignments. PMID:22665781

  12. Global Collaborative STEM Education

    NASA Astrophysics Data System (ADS)

    Meabh Kelly, Susan; Smith, Walter

    2016-04-01

    Global Collaborative STEM Education, as the name suggests, simultaneously supports two sets of knowledge and skills. The first set is STEM -- science, technology, engineering and math. The other set of content knowledge and skills is that of global collaboration. Successful global partnerships require awareness of one's own culture, the biases embedded within that culture, as well as developing awareness of the collaborators' culture. Workforce skills fostered include open-mindedness, perseverance when faced with obstacles, and resourceful use of technological "bridges" to facilitate and sustain communication. In respect for the 2016 GIFT Workshop focus, Global Collaborative STEM Education projects dedicated to astronomy research will be presented. The projects represent different benchmarks within the Global Collaborative STEM Education continuum, culminating in an astronomy research experience that fully reflects how the global STEM workforce collaborates. To facilitate wider engagement in Global Collaborative STEM Education, project summaries, classroom resources and contact information for established international collaborative astronomy research projects will be disseminated.

  13. An accurate and efficient algorithm for Faraday rotation corrections for spaceborne microwave radiometers

    NASA Astrophysics Data System (ADS)

    Singh, Malkiat; Bettenhausen, Michael H.

    2011-08-01

    Faraday rotation changes the polarization plane of linearly polarized microwaves which propagate through the ionosphere. To correct for ionospheric polarization error, it is necessary to have electron density profiles on a global scale that represent the ionosphere in real time. We use raytrace through the combined models of ionospheric conductivity and electron density (ICED), Bent, and Gallagher models (RIBG model) to specify the ionospheric conditions by ingesting the GPS data from observing stations that are as close as possible to the observation time and location of the space system for which the corrections are required. To accurately calculate Faraday rotation corrections, we also utilize the raytrace utility of the RIBG model instead of the normal shell model assumption for the ionosphere. We use WindSat data, which exhibits a wide range of orientations of the raypath and a high data rate of observations, to provide a realistic data set for analysis. The standard single-shell models at 350 and 400 km are studied along with a new three-shell model and compared with the raytrace method for computation time and accuracy. We have compared the Faraday results obtained with climatological (International Reference Ionosphere and RIBG) and physics-based (Global Assimilation of Ionospheric Measurements) ionospheric models. We also study the impact of limitations in the availability of GPS data on the accuracy of the Faraday rotation calculations.

  14. Improved Algorithms for Accurate Retrieval of UV - Visible Diffuse Attenuation Coefficients in Optically Complex, Inshore Waters

    NASA Technical Reports Server (NTRS)

    Cao, Fang; Fichot, Cedric G.; Hooker, Stanford B.; Miller, William L.

    2014-01-01

    Photochemical processes driven by high-energy ultraviolet radiation (UVR) in inshore, estuarine, and coastal waters play an important role in global bio geochemical cycles and biological systems. A key to modeling photochemical processes in these optically complex waters is an accurate description of the vertical distribution of UVR in the water column which can be obtained using the diffuse attenuation coefficients of down welling irradiance (Kd()). The Sea UV Sea UVc algorithms (Fichot et al., 2008) can accurately retrieve Kd ( 320, 340, 380,412, 443 and 490 nm) in oceanic and coastal waters using multispectral remote sensing reflectances (Rrs(), Sea WiFS bands). However, SeaUVSeaUVc algorithms are currently not optimized for use in optically complex, inshore waters, where they tend to severely underestimate Kd(). Here, a new training data set of optical properties collected in optically complex, inshore waters was used to re-parameterize the published SeaUVSeaUVc algorithms, resulting in improved Kd() retrievals for turbid, estuarine waters. Although the updated SeaUVSeaUVc algorithms perform best in optically complex waters, the published SeaUVSeaUVc models still perform well in most coastal and oceanic waters. Therefore, we propose a composite set of SeaUVSeaUVc algorithms, optimized for Kd() retrieval in almost all marine systems, ranging from oceanic to inshore waters. The composite algorithm set can retrieve Kd from ocean color with good accuracy across this wide range of water types (e.g., within 13 mean relative error for Kd(340)). A validation step using three independent, in situ data sets indicates that the composite SeaUVSeaUVc can generate accurate Kd values from 320 490 nm using satellite imagery on a global scale. Taking advantage of the inherent benefits of our statistical methods, we pooled the validation data with the training set, obtaining an optimized composite model for estimating Kd() in UV wavelengths for almost all marine waters. This

  15. Fast and accurate estimation for astrophysical problems in large databases

    NASA Astrophysics Data System (ADS)

    Richards, Joseph W.

    2010-10-01

    A recent flood of astronomical data has created much demand for sophisticated statistical and machine learning tools that can rapidly draw accurate inferences from large databases of high-dimensional data. In this Ph.D. thesis, methods for statistical inference in such databases will be proposed, studied, and applied to real data. I use methods for low-dimensional parametrization of complex, high-dimensional data that are based on the notion of preserving the connectivity of data points in the context of a Markov random walk over the data set. I show how this simple parameterization of data can be exploited to: define appropriate prototypes for use in complex mixture models, determine data-driven eigenfunctions for accurate nonparametric regression, and find a set of suitable features to use in a statistical classifier. In this thesis, methods for each of these tasks are built up from simple principles, compared to existing methods in the literature, and applied to data from astronomical all-sky surveys. I examine several important problems in astrophysics, such as estimation of star formation history parameters for galaxies, prediction of redshifts of galaxies using photometric data, and classification of different types of supernovae based on their photometric light curves. Fast methods for high-dimensional data analysis are crucial in each of these problems because they all involve the analysis of complicated high-dimensional data in large, all-sky surveys. Specifically, I estimate the star formation history parameters for the nearly 800,000 galaxies in the Sloan Digital Sky Survey (SDSS) Data Release 7 spectroscopic catalog, determine redshifts for over 300,000 galaxies in the SDSS photometric catalog, and estimate the types of 20,000 supernovae as part of the Supernova Photometric Classification Challenge. Accurate predictions and classifications are imperative in each of these examples because these estimates are utilized in broader inference problems

  16. Fast and Accurate Construction of Confidence Intervals for Heritability.

    PubMed

    Schweiger, Regev; Kaufman, Shachar; Laaksonen, Reijo; Kleber, Marcus E; März, Winfried; Eskin, Eleazar; Rosset, Saharon; Halperin, Eran

    2016-06-01

    Estimation of heritability is fundamental in genetic studies. Recently, heritability estimation using linear mixed models (LMMs) has gained popularity because these estimates can be obtained from unrelated individuals collected in genome-wide association studies. Typically, heritability estimation under LMMs uses the restricted maximum likelihood (REML) approach. Existing methods for the construction of confidence intervals and estimators of SEs for REML rely on asymptotic properties. However, these assumptions are often violated because of the bounded parameter space, statistical dependencies, and limited sample size, leading to biased estimates and inflated or deflated confidence intervals. Here, we show that the estimation of confidence intervals by state-of-the-art methods is inaccurate, especially when the true heritability is relatively low or relatively high. We further show that these inaccuracies occur in datasets including thousands of individuals. Such biases are present, for example, in estimates of heritability of gene expression in the Genotype-Tissue Expression project and of lipid profiles in the Ludwigshafen Risk and Cardiovascular Health study. We also show that often the probability that the genetic component is estimated as 0 is high even when the true heritability is bounded away from 0, emphasizing the need for accurate confidence intervals. We propose a computationally efficient method, ALBI (accurate LMM-based heritability bootstrap confidence intervals), for estimating the distribution of the heritability estimator and for constructing accurate confidence intervals. Our method can be used as an add-on to existing methods for estimating heritability and variance components, such as GCTA, FaST-LMM, GEMMA, or EMMAX. PMID:27259052

  17. D-BRAIN: Anatomically Accurate Simulated Diffusion MRI Brain Data.

    PubMed

    Perrone, Daniele; Jeurissen, Ben; Aelterman, Jan; Roine, Timo; Sijbers, Jan; Pizurica, Aleksandra; Leemans, Alexander; Philips, Wilfried

    2016-01-01

    Diffusion Weighted (DW) MRI allows for the non-invasive study of water diffusion inside living tissues. As such, it is useful for the investigation of human brain white matter (WM) connectivity in vivo through fiber tractography (FT) algorithms. Many DW-MRI tailored restoration techniques and FT algorithms have been developed. However, it is not clear how accurately these methods reproduce the WM bundle characteristics in real-world conditions, such as in the presence of noise, partial volume effect, and a limited spatial and angular resolution. The difficulty lies in the lack of a realistic brain phantom on the one hand, and a sufficiently accurate way of modeling the acquisition-related degradation on the other. This paper proposes a software phantom that approximates a human brain to a high degree of realism and that can incorporate complex brain-like structural features. We refer to it as a Diffusion BRAIN (D-BRAIN) phantom. Also, we propose an accurate model of a (DW) MRI acquisition protocol to allow for validation of methods in realistic conditions with data imperfections. The phantom model simulates anatomical and diffusion properties for multiple brain tissue components, and can serve as a ground-truth to evaluate FT algorithms, among others. The simulation of the acquisition process allows one to include noise, partial volume effects, and limited spatial and angular resolution in the images. In this way, the effect of image artifacts on, for instance, fiber tractography can be investigated with great detail. The proposed framework enables reliable and quantitative evaluation of DW-MR image processing and FT algorithms at the level of large-scale WM structures. The effect of noise levels and other data characteristics on cortico-cortical connectivity and tractography-based grey matter parcellation can be investigated as well. PMID:26930054

  18. The FLUKA Code: An Accurate Simulation Tool for Particle Therapy

    PubMed Central

    Battistoni, Giuseppe; Bauer, Julia; Boehlen, Till T.; Cerutti, Francesco; Chin, Mary P. W.; Dos Santos Augusto, Ricardo; Ferrari, Alfredo; Ortega, Pablo G.; Kozłowska, Wioletta; Magro, Giuseppe; Mairani, Andrea; Parodi, Katia; Sala, Paola R.; Schoofs, Philippe; Tessonnier, Thomas; Vlachoudis, Vasilis

    2016-01-01

    Monte Carlo (MC) codes are increasingly spreading in the hadrontherapy community due to their detailed description of radiation transport and interaction with matter. The suitability of a MC code for application to hadrontherapy demands accurate and reliable physical models capable of handling all components of the expected radiation field. This becomes extremely important for correctly performing not only physical but also biologically based dose calculations, especially in cases where ions heavier than protons are involved. In addition, accurate prediction of emerging secondary radiation is of utmost importance in innovative areas of research aiming at in vivo treatment verification. This contribution will address the recent developments of the FLUKA MC code and its practical applications in this field. Refinements of the FLUKA nuclear models in the therapeutic energy interval lead to an improved description of the mixed radiation field as shown in the presented benchmarks against experimental data with both 4He and 12C ion beams. Accurate description of ionization energy losses and of particle scattering and interactions lead to the excellent agreement of calculated depth–dose profiles with those measured at leading European hadron therapy centers, both with proton and ion beams. In order to support the application of FLUKA in hospital-based environments, Flair, the FLUKA graphical interface, has been enhanced with the capability of translating CT DICOM images into voxel-based computational phantoms in a fast and well-structured way. The interface is capable of importing also radiotherapy treatment data described in DICOM RT standard. In addition, the interface is equipped with an intuitive PET scanner geometry generator and automatic recording of coincidence events. Clinically, similar cases will be presented both in terms of absorbed dose and biological dose calculations describing the various available features. PMID:27242956

  19. An accurate analytic representation of the water pair potential.

    PubMed

    Cencek, Wojciech; Szalewicz, Krzysztof; Leforestier, Claude; van Harrevelt, Rob; van der Avoird, Ad

    2008-08-28

    The ab initio water dimer interaction energies obtained from coupled cluster calculations and used in the CC-pol water pair potential (Bukowski et al., Science, 2007, 315, 1249) have been refitted to a site-site form containing eight symmetry-independent sites in each monomer and denoted as CC-pol-8s. Initially, the site-site functions were assumed in a B-spline form, which allowed a precise optimization of the positions of the sites. Next, these functions were assumed in the standard exponential plus inverse powers form. The root mean square error of the CC-pol-8s fit with respect to the 2510 ab initio points is 0.10 kcal mol(-1), compared to 0.42 kcal mol(-1) of the CC-pol fit (0.010 kcal mol(-1) compared to 0.089 kcal mol(-1) for points with negative interaction energies). The energies of the stationary points in the CC-pol-8s potential are considerably more accurate than in the case of CC-pol. The water dimer vibration-rotation-tunneling spectrum predicted by the CC-pol-8s potential agrees substantially and systematically better with experiment than the already very accurate spectrum predicted by CC-pol, while specific features that could not be accurately predicted previously now agree very well with experiment. This shows that the uncertainties of the fit were the largest source of error in the previous predictions and that the present potential sets a new standard of accuracy in investigations of the water dimer. PMID:18688514

  20. D-BRAIN: Anatomically Accurate Simulated Diffusion MRI Brain Data

    PubMed Central

    Perrone, Daniele; Jeurissen, Ben; Aelterman, Jan; Roine, Timo; Sijbers, Jan; Pizurica, Aleksandra; Leemans, Alexander; Philips, Wilfried

    2016-01-01

    Diffusion Weighted (DW) MRI allows for the non-invasive study of water diffusion inside living tissues. As such, it is useful for the investigation of human brain white matter (WM) connectivity in vivo through fiber tractography (FT) algorithms. Many DW-MRI tailored restoration techniques and FT algorithms have been developed. However, it is not clear how accurately these methods reproduce the WM bundle characteristics in real-world conditions, such as in the presence of noise, partial volume effect, and a limited spatial and angular resolution. The difficulty lies in the lack of a realistic brain phantom on the one hand, and a sufficiently accurate way of modeling the acquisition-related degradation on the other. This paper proposes a software phantom that approximates a human brain to a high degree of realism and that can incorporate complex brain-like structural features. We refer to it as a Diffusion BRAIN (D-BRAIN) phantom. Also, we propose an accurate model of a (DW) MRI acquisition protocol to allow for validation of methods in realistic conditions with data imperfections. The phantom model simulates anatomical and diffusion properties for multiple brain tissue components, and can serve as a ground-truth to evaluate FT algorithms, among others. The simulation of the acquisition process allows one to include noise, partial volume effects, and limited spatial and angular resolution in the images. In this way, the effect of image artifacts on, for instance, fiber tractography can be investigated with great detail. The proposed framework enables reliable and quantitative evaluation of DW-MR image processing and FT algorithms at the level of large-scale WM structures. The effect of noise levels and other data characteristics on cortico-cortical connectivity and tractography-based grey matter parcellation can be investigated as well. PMID:26930054

  1. The FLUKA Code: An Accurate Simulation Tool for Particle Therapy.

    PubMed

    Battistoni, Giuseppe; Bauer, Julia; Boehlen, Till T; Cerutti, Francesco; Chin, Mary P W; Dos Santos Augusto, Ricardo; Ferrari, Alfredo; Ortega, Pablo G; Kozłowska, Wioletta; Magro, Giuseppe; Mairani, Andrea; Parodi, Katia; Sala, Paola R; Schoofs, Philippe; Tessonnier, Thomas; Vlachoudis, Vasilis

    2016-01-01

    Monte Carlo (MC) codes are increasingly spreading in the hadrontherapy community due to their detailed description of radiation transport and interaction with matter. The suitability of a MC code for application to hadrontherapy demands accurate and reliable physical models capable of handling all components of the expected radiation field. This becomes extremely important for correctly performing not only physical but also biologically based dose calculations, especially in cases where ions heavier than protons are involved. In addition, accurate prediction of emerging secondary radiation is of utmost importance in innovative areas of research aiming at in vivo treatment verification. This contribution will address the recent developments of the FLUKA MC code and its practical applications in this field. Refinements of the FLUKA nuclear models in the therapeutic energy interval lead to an improved description of the mixed radiation field as shown in the presented benchmarks against experimental data with both (4)He and (12)C ion beams. Accurate description of ionization energy losses and of particle scattering and interactions lead to the excellent agreement of calculated depth-dose profiles with those measured at leading European hadron therapy centers, both with proton and ion beams. In order to support the application of FLUKA in hospital-based environments, Flair, the FLUKA graphical interface, has been enhanced with the capability of translating CT DICOM images into voxel-based computational phantoms in a fast and well-structured way. The interface is capable of importing also radiotherapy treatment data described in DICOM RT standard. In addition, the interface is equipped with an intuitive PET scanner geometry generator and automatic recording of coincidence events. Clinically, similar cases will be presented both in terms of absorbed dose and biological dose calculations describing the various available features. PMID:27242956

  2. The importance of accurate convergence in addressing stereoscopic visual fatigue

    NASA Astrophysics Data System (ADS)

    Mayhew, Christopher A.

    2015-03-01

    Visual fatigue (asthenopia) continues to be a problem in extended viewing of stereoscopic imagery. Poorly converged imagery may contribute to this problem. In 2013, the Author reported that in a study sample a surprisingly high number of 3D feature films released as stereoscopic Blu-rays contained obvious convergence errors.1 The placement of stereoscopic image convergence can be an "artistic" call, but upon close examination, the sampled films seemed to have simply missed their intended convergence location. This failure maybe because some stereoscopic editing tools do not have the necessary fidelity to enable a 3D editor to obtain a high degree of image alignment or set an exact point of convergence. Compounding this matter further is the fact that a large number of stereoscopic editors may not believe that pixel accurate alignment and convergence is necessary. The Author asserts that setting a pixel accurate point of convergence on an object at the start of any given stereoscopic scene will improve the viewer's ability to fuse the left and right images quickly. The premise is that stereoscopic performance (acuity) increases when an accurately converged object is available in the image for the viewer to fuse immediately. Furthermore, this increased viewer stereoscopic performance should reduce the amount of visual fatigue associated with longer-term viewing because less mental effort will be required to perceive the imagery. To test this concept, we developed special stereoscopic imagery to measure viewer visual performance with and without specific objects for convergence. The Company Team conducted a series of visual tests with 24 participants between 25 and 60 years of age. This paper reports the results of these tests.

  3. Global warming without global mean precipitation increase?

    PubMed

    Salzmann, Marc

    2016-06-01

    Global climate models simulate a robust increase of global mean precipitation of about 1.5 to 2% per kelvin surface warming in response to greenhouse gas (GHG) forcing. Here, it is shown that the sensitivity to aerosol cooling is robust as well, albeit roughly twice as large. This larger sensitivity is consistent with energy budget arguments. At the same time, it is still considerably lower than the 6.5 to 7% K(-1) decrease of the water vapor concentration with cooling from anthropogenic aerosol because the water vapor radiative feedback lowers the hydrological sensitivity to anthropogenic forcings. When GHG and aerosol forcings are combined, the climate models with a realistic 20th century warming indicate that the global mean precipitation increase due to GHG warming has, until recently, been completely masked by aerosol drying. This explains the apparent lack of sensitivity of the global mean precipitation to the net global warming recently found in observations. As the importance of GHG warming increases in the future, a clear signal will emerge. PMID:27386558

  4. Global warming without global mean precipitation increase?

    PubMed Central

    Salzmann, Marc

    2016-01-01

    Global climate models simulate a robust increase of global mean precipitation of about 1.5 to 2% per kelvin surface warming in response to greenhouse gas (GHG) forcing. Here, it is shown that the sensitivity to aerosol cooling is robust as well, albeit roughly twice as large. This larger sensitivity is consistent with energy budget arguments. At the same time, it is still considerably lower than the 6.5 to 7% K−1 decrease of the water vapor concentration with cooling from anthropogenic aerosol because the water vapor radiative feedback lowers the hydrological sensitivity to anthropogenic forcings. When GHG and aerosol forcings are combined, the climate models with a realistic 20th century warming indicate that the global mean precipitation increase due to GHG warming has, until recently, been completely masked by aerosol drying. This explains the apparent lack of sensitivity of the global mean precipitation to the net global warming recently found in observations. As the importance of GHG warming increases in the future, a clear signal will emerge. PMID:27386558

  5. Accurate evaluation of homogenous and nonhomogeneous gas emissivities

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Lee, K. P.

    1984-01-01

    Spectral transmittance and total band adsorptance of selected infrared bands of carbon dioxide and water vapor are calculated by using the line-by-line and quasi-random band models and these are compared with available experimental results to establish the validity of the quasi-random band model. Various wide-band model correlations are employed to calculate the total band absorptance and total emissivity of these two gases under homogeneous and nonhomogeneous conditions. These results are compared with available experimental results under identical conditions. From these comparisons, it is found that the quasi-random band model can provide quite accurate results and is quite suitable for most atmospheric applications.

  6. Accurate pressure gradient calculations in hydrostatic atmospheric models

    NASA Technical Reports Server (NTRS)

    Carroll, John J.; Mendez-Nunez, Luis R.; Tanrikulu, Saffet

    1987-01-01

    A method for the accurate calculation of the horizontal pressure gradient acceleration in hydrostatic atmospheric models is presented which is especially useful in situations where the isothermal surfaces are not parallel to the vertical coordinate surfaces. The present method is shown to be exact if the potential temperature lapse rate is constant between the vertical pressure integration limits. The technique is applied to both the integration of the hydrostatic equation and the computation of the slope correction term in the horizontal pressure gradient. A fixed vertical grid and a dynamic grid defined by the significant levels in the vertical temperature distribution are employed.

  7. Accurate strain measurements in highly strained Ge microbridges

    NASA Astrophysics Data System (ADS)

    Gassenq, A.; Tardif, S.; Guilloy, K.; Osvaldo Dias, G.; Pauc, N.; Duchemin, I.; Rouchon, D.; Hartmann, J.-M.; Widiez, J.; Escalante, J.; Niquet, Y.-M.; Geiger, R.; Zabel, T.; Sigg, H.; Faist, J.; Chelnokov, A.; Rieutord, F.; Reboud, V.; Calvo, V.

    2016-06-01

    Ge under high strain is predicted to become a direct bandgap semiconductor. Very large deformations can be introduced using microbridge devices. However, at the microscale, strain values are commonly deduced from Raman spectroscopy using empirical linear models only established up to ɛ100 = 1.2% for uniaxial stress. In this work, we calibrate the Raman-strain relation at higher strain using synchrotron based microdiffraction. The Ge microbridges show unprecedented high tensile strain up to 4.9% corresponding to an unexpected Δω = 9.9 cm-1 Raman shift. We demonstrate experimentally and theoretically that the Raman strain relation is not linear and we provide a more accurate expression.

  8. Accurate analysis of EBSD data for phase identification

    NASA Astrophysics Data System (ADS)

    Palizdar, Y.; Cochrane, R. C.; Brydson, R.; Leary, R.; Scott, A. J.

    2010-07-01

    This paper aims to investigate the reliability of software default settings in the analysis of EBSD results. To study the effect of software settings on the EBSD results, the presence of different phases in high Al steel has been investigated by EBSD. The results show the importance of appropriate automated analysis parameters for valid and reliable phase discrimination. Specifically, the importance of the minimum number of indexed bands and the maximum solution error have been investigated with values of 7-9 and 1.0-1.5° respectively, found to be needed for accurate analysis.

  9. Beam Profile Monitor With Accurate Horizontal And Vertical Beam Profiles

    DOEpatents

    Havener, Charles C [Knoxville, TN; Al-Rejoub, Riad [Oak Ridge, TN

    2005-12-26

    A widely used scanner device that rotates a single helically shaped wire probe in and out of a particle beam at different beamline positions to give a pair of mutually perpendicular beam profiles is modified by the addition of a second wire probe. As a result, a pair of mutually perpendicular beam profiles is obtained at a first beamline position, and a second pair of mutually perpendicular beam profiles is obtained at a second beamline position. The simple modification not only provides more accurate beam profiles, but also provides a measurement of the beam divergence and quality in a single compact device.

  10. Vibration of clamped right triangular thin plates: Accurate simplified solutions

    NASA Astrophysics Data System (ADS)

    Saliba, H. T.

    1994-12-01

    Use of the superposition techniques in the free-vibration analyses of thin plates, as they were first introduced by Gorman, has provided simple and effective solutions to a vast number of rectangular plate problems. A modified superposition method is presented that is a noticeable improvement over existing techniques. It deals only with simple support conditions, leading to a simple, highly accurate, and very economical solution to the free-vibration problem of simply-supported right angle triangular plates. The modified method is also applicable to clamped-edge conditions.

  11. Accurate LTE abundances for some lambda Boo stars

    NASA Astrophysics Data System (ADS)

    Andrievsky, S. M.; Chernyshova, I. V.; Klochkova, V. G.; Panchuk, V. E.

    1998-04-01

    High-resolution and high S/N CCD spectra were analyzed to determine accurate LTE abundances in four lambda Boo stars: pi1 Ori, 29 Cyg, HR 8203 and 15 And. In general, 14 chemical elements were investigated. The main results are the following: all stars have a strong deficiency of the majority of investigated metals. Oxygen exhibits a moderate deficiency. The carbon abundance is close to the solar one. The results obtained support an accretion/diffusion model, which is currently adopted for the explanation of the lambda Boo phenomenon.

  12. Pink-Beam, Highly-Accurate Compact Water Cooled Slits

    SciTech Connect

    Lyndaker, Aaron; Deyhim, Alex; Jayne, Richard; Waterman, Dave; Caletka, Dave; Steadman, Paul; Dhesi, Sarnjeet

    2007-01-19

    Advanced Design Consulting, Inc. (ADC) has designed accurate compact slits for applications where high precision is required. The system consists of vertical and horizontal slit mechanisms, a vacuum vessel which houses them, water cooling lines with vacuum guards connected to the individual blades, stepper motors with linear encoders, limit (home position) switches and electrical connections including internal wiring for a drain current measurement system. The total slit size is adjustable from 0 to 15 mm both vertically and horizontally. Each of the four blades are individually controlled and motorized. In this paper, a summary of the design and Finite Element Analysis of the system are presented.

  13. Detection and accurate localization of harmonic chipless tags

    NASA Astrophysics Data System (ADS)

    Dardari, Davide

    2015-12-01

    We investigate the detection and localization properties of harmonic tags working at microwave frequencies. A two-tone interrogation signal and a dedicated signal processing scheme at the receiver are proposed to eliminate phase ambiguities caused by the short signal wavelength and to provide accurate distance/position estimation even in the presence of clutter and multipath. The theoretical limits on tag detection and localization accuracy are investigated starting from a concise characterization of harmonic backscattered signals. Numerical results show that accuracies in the order of centimeters are feasible within an operational range of a few meters in the RFID UHF band.

  14. Accurate and Sensitive Peptide Identification with Mascot Percolator

    PubMed Central

    Brosch, Markus; Yu, Lu; Hubbard, Tim; Choudhary, Jyoti

    2009-01-01

    Sound scoring methods for sequence database search algorithms such as Mascot and Sequest are essential for sensitive and accurate peptide and protein identifications from proteomic tandem mass spectrometry data. In this paper, we present a software package that interfaces Mascot with Percolator, a well performing machine learning method for rescoring database search results, and demonstrate it to be amenable for both low and high accuracy mass spectrometry data, outperforming all available Mascot scoring schemes as well as providing reliable significance measures. Mascot Percolator can be readily used as a stand alone tool or integrated into existing data analysis pipelines. PMID:19338334

  15. Calibration Techniques for Accurate Measurements by Underwater Camera Systems.

    PubMed

    Shortis, Mark

    2015-01-01

    Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems. PMID:26690172

  16. Accurate method of modeling cluster scaling relations in modified gravity

    NASA Astrophysics Data System (ADS)

    He, Jian-hua; Li, Baojiu

    2016-06-01

    We propose a new method to model cluster scaling relations in modified gravity. Using a suite of nonradiative hydrodynamical simulations, we show that the scaling relations of accumulated gas quantities, such as the Sunyaev-Zel'dovich effect (Compton-y parameter) and the x-ray Compton-y parameter, can be accurately predicted using the known results in the Λ CDM model with a precision of ˜3 % . This method provides a reliable way to analyze the gas physics in modified gravity using the less demanding and much more efficient pure cold dark matter simulations. Our results therefore have important theoretical and practical implications in constraining gravity using cluster surveys.

  17. Accurate energy levels for singly ionized platinum (Pt II)

    NASA Technical Reports Server (NTRS)

    Reader, Joseph; Acquista, Nicolo; Sansonetti, Craig J.; Engleman, Rolf, Jr.

    1988-01-01

    New observations of the spectrum of Pt II have been made with hollow-cathode lamps. The region from 1032 to 4101 A was observed photographically with a 10.7-m normal-incidence spectrograph. The region from 2245 to 5223 A was observed with a Fourier-transform spectrometer. Wavelength measurements were made for 558 lines. The uncertainties vary from 0.0005 to 0.004 A. From these measurements and three parity-forbidden transitions in the infrared, accurate values were determined for 28 even and 72 odd energy levels of Pt II.

  18. Accurate dynamics in an azimuthally-symmetric accelerating cavity

    NASA Astrophysics Data System (ADS)

    Appleby, R. B.; Abell, D. T.

    2015-02-01

    We consider beam dynamics in azimuthally-symmetric accelerating cavities, using the EMMA FFAG cavity as an example. By fitting a vector potential to the field map, we represent the linear and non-linear dynamics using truncated power series and mixed-variable generating functions. The analysis provides an accurate model for particle trajectories in the cavity, reveals potentially significant and measurable effects on the dynamics, and shows differences between cavity focusing models. The approach provides a unified treatment of transverse and longitudinal motion, and facilitates detailed map-based studies of motion in complex machines like FFAGs.

  19. Calibration Techniques for Accurate Measurements by Underwater Camera Systems

    PubMed Central

    Shortis, Mark

    2015-01-01

    Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems. PMID:26690172

  20. Accurate Excited State Geometries within Reduced Subspace TDDFT/TDA.

    PubMed

    Robinson, David

    2014-12-01

    A method for the calculation of TDDFT/TDA excited state geometries within a reduced subspace of Kohn-Sham orbitals has been implemented and tested. Accurate geometries are found for all of the fluorophore-like molecules tested, with at most all valence occupied orbitals and half of the virtual orbitals included but for some molecules even fewer orbitals. Efficiency gains of between 15 and 30% are found for essentially the same level of accuracy as a standard TDDFT/TDA excited state geometry optimization calculation. PMID:26583218

  1. Childhood stunting: a global perspective.

    PubMed

    de Onis, Mercedes; Branca, Francesco

    2016-05-01

    Childhood stunting is the best overall indicator of children's well-being and an accurate reflection of social inequalities. Stunting is the most prevalent form of child malnutrition with an estimated 161 million children worldwide in 2013 falling below -2 SD from the length-for-age/height-for-age World Health Organization Child Growth Standards median. Many more millions suffer from some degree of growth faltering as the entire length-for-age/height-for-age z-score distribution is shifted to the left indicating that all children, and not only those falling below a specific cutoff, are affected. Despite global consensus on how to define and measure it, stunting often goes unrecognized in communities where short stature is the norm as linear growth is not routinely assessed in primary health care settings and it is difficult to visually recognize it. Growth faltering often begins in utero and continues for at least the first 2 years of post-natal life. Linear growth failure serves as a marker of multiple pathological disorders associated with increased morbidity and mortality, loss of physical growth potential, reduced neurodevelopmental and cognitive function and an elevated risk of chronic disease in adulthood. The severe irreversible physical and neurocognitive damage that accompanies stunted growth poses a major threat to human development. Increased awareness of stunting's magnitude and devastating consequences has resulted in its being identified as a major global health priority and the focus of international attention at the highest levels with global targets set for 2025 and beyond. The challenge is to prevent linear growth failure while keeping child overweight and obesity at bay. PMID:27187907

  2. RRTMGP: A fast and accurate radiation code for the next decade

    NASA Astrophysics Data System (ADS)

    Mlawer, E. J.; Pincus, R.; Wehe, A.; Delamere, J.

    2015-12-01

    Atmospheric radiative processes are key drivers of the Earth's climate and must be accurately represented in global circulations models (GCMs) to allow faithful simulations of the planet's past, present, and future. The radiation code RRTMG is widely utilized by global modeling centers for both climate and weather predictions, but it has become increasingly out-of-date. The code's structure is not well suited for the current generation of computer architectures and its stored absorption coefficients are not consistent with the most recent spectroscopic information. We are developing a new broadband radiation code for the current generation of computational architectures. This code, called RRTMGP, will be a completely restructured and modern version of RRTMG. The new code preserves the strengths of the existing RRTMG parameterization, especially the high accuracy of the k-distribution treatment of absorption by gases, but the entire code is being rewritten to provide highly efficient computation across a range of architectures. Our redesign includes refactoring the code into discrete kernels corresponding to fundamental computational elements (e.g. gas optics), optimizing the code for operating on multiple columns in parallel, simplifying the subroutine interface, revisiting the existing gas optics interpolation scheme to reduce branching, and adding flexibility with respect to run-time choices of streams, need for consideration of scattering, aerosol and cloud optics, etc. The result of the proposed development will be a single, well-supported and well-validated code amenable to optimization across a wide range of platforms. Our main emphasis is on highly-parallel platforms including Graphical Processing Units (GPUs) and Many-Integrated-Core processors (MICs), which experience shows can accelerate broadband radiation calculations by as much as a factor of fifty. RRTMGP will provide highly efficient and accurate radiative fluxes calculations for coupled global

  3. GIS TECHNICAL MEMORANDUM 3: GLOBAL POSITIONING SYSTEMS TECHNOLOGY AND ITS APPLICATION IN ENVIRONMENTAL PROGRAMS.

    EPA Science Inventory

    Global Positioning Systems (GPS) are a location determination technology that offers significance opportunities for obtaining highly accurate locational data at low costs. n order for the technology to perform up to its capabilities in Agency applications, Environmental Protectio...

  4. Highly Accurate Inverse Consistent Registration: A Robust Approach

    PubMed Central

    Reuter, Martin; Rosas, H. Diana; Fischl, Bruce

    2010-01-01

    The registration of images is a task that is at the core of many applications in computer vision. In computational neuroimaging where the automated segmentation of brain structures is frequently used to quantify change, a highly accurate registration is necessary for motion correction of images taken in the same session, or across time in longitudinal studies where changes in the images can be expected. This paper, inspired by Nestares and Heeger (2000), presents a method based on robust statistics to register images in the presence of differences, such as jaw movement, differential MR distortions and true anatomical change. The approach we present guarantees inverse consistency (symmetry), can deal with different intensity scales and automatically estimates a sensitivity parameter to detect outlier regions in the images. The resulting registrations are highly accurate due to their ability to ignore outlier regions and show superior robustness with respect to noise, to intensity scaling and outliers when compared to state-of-the-art registration tools such as FLIRT (in FSL) or the coregistration tool in SPM. PMID:20637289

  5. Strategy for accurate liver intervention by an optical tracking system

    PubMed Central

    Lin, Qinyong; Yang, Rongqian; Cai, Ken; Guan, Peifeng; Xiao, Weihu; Wu, Xiaoming

    2015-01-01

    Image-guided navigation for radiofrequency ablation of liver tumors requires the accurate guidance of needle insertion into a tumor target. The main challenge of image-guided navigation for radiofrequency ablation of liver tumors is the occurrence of liver deformations caused by respiratory motion. This study reports a strategy of real-time automatic registration to track custom fiducial markers glued onto the surface of a patient’s abdomen to find the respiratory phase, in which the static preoperative CT is performed. Custom fiducial markers are designed. Real-time automatic registration method consists of the automatic localization of custom fiducial markers in the patient and image spaces. The fiducial registration error is calculated in real time and indicates if the current respiratory phase corresponds to the phase of the static preoperative CT. To demonstrate the feasibility of the proposed strategy, a liver simulator is constructed and two volunteers are involved in the preliminary experiments. An ex-vivo porcine liver model is employed to further verify the strategy for liver intervention. Experimental results demonstrate that real-time automatic registration method is rapid, accurate, and feasible for capturing the respiratory phase from which the static preoperative CT anatomical model is generated by tracking the movement of the skin-adhered custom fiducial markers. PMID:26417501

  6. A Highly Accurate Face Recognition System Using Filtering Correlation

    NASA Astrophysics Data System (ADS)

    Watanabe, Eriko; Ishikawa, Sayuri; Kodate, Kashiko

    2007-09-01

    The authors previously constructed a highly accurate fast face recognition optical correlator (FARCO) [E. Watanabe and K. Kodate: Opt. Rev. 12 (2005) 460], and subsequently developed an improved, super high-speed FARCO (S-FARCO), which is able to process several hundred thousand frames per second. The principal advantage of our new system is its wide applicability to any correlation scheme. Three different configurations were proposed, each depending on correlation speed. This paper describes and evaluates a software correlation filter. The face recognition function proved highly accurate, seeing that a low-resolution facial image size (64 × 64 pixels) has been successfully implemented. An operation speed of less than 10 ms was achieved using a personal computer with a central processing unit (CPU) of 3 GHz and 2 GB memory. When we applied the software correlation filter to a high-security cellular phone face recognition system, experiments on 30 female students over a period of three months yielded low error rates: 0% false acceptance rate and 2% false rejection rate. Therefore, the filtering correlation works effectively when applied to low resolution images such as web-based images or faces captured by a monitoring camera.

  7. Mouse models of human AML accurately predict chemotherapy response

    PubMed Central

    Zuber, Johannes; Radtke, Ina; Pardee, Timothy S.; Zhao, Zhen; Rappaport, Amy R.; Luo, Weijun; McCurrach, Mila E.; Yang, Miao-Miao; Dolan, M. Eileen; Kogan, Scott C.; Downing, James R.; Lowe, Scott W.

    2009-01-01

    The genetic heterogeneity of cancer influences the trajectory of tumor progression and may underlie clinical variation in therapy response. To model such heterogeneity, we produced genetically and pathologically accurate mouse models of common forms of human acute myeloid leukemia (AML) and developed methods to mimic standard induction chemotherapy and efficiently monitor therapy response. We see that murine AMLs harboring two common human AML genotypes show remarkably diverse responses to conventional therapy that mirror clinical experience. Specifically, murine leukemias expressing the AML1/ETO fusion oncoprotein, associated with a favorable prognosis in patients, show a dramatic response to induction chemotherapy owing to robust activation of the p53 tumor suppressor network. Conversely, murine leukemias expressing MLL fusion proteins, associated with a dismal prognosis in patients, are drug-resistant due to an attenuated p53 response. Our studies highlight the importance of genetic information in guiding the treatment of human AML, functionally establish the p53 network as a central determinant of chemotherapy response in AML, and demonstrate that genetically engineered mouse models of human cancer can accurately predict therapy response in patients. PMID:19339691

  8. Accurate and efficient reconstruction of deep phylogenies from structured RNAs

    PubMed Central

    Stocsits, Roman R.; Letsch, Harald; Hertel, Jana; Misof, Bernhard; Stadler, Peter F.

    2009-01-01

    Ribosomal RNA (rRNA) genes are probably the most frequently used data source in phylogenetic reconstruction. Individual columns of rRNA alignments are not independent as a consequence of their highly conserved secondary structures. Unless explicitly taken into account, these correlation can distort the phylogenetic signal and/or lead to gross overestimates of tree stability. Maximum likelihood and Bayesian approaches are of course amenable to using RNA-specific substitution models that treat conserved base pairs appropriately, but require accurate secondary structure models as input. So far, however, no accurate and easy-to-use tool has been available for computing structure-aware alignments and consensus structures that can deal with the large rRNAs. The RNAsalsa approach is designed to fill this gap. Capitalizing on the improved accuracy of pairwise consensus structures and informed by a priori knowledge of group-specific structural constraints, the tool provides both alignments and consensus structures that are of sufficient accuracy for routine phylogenetic analysis based on RNA-specific substitution models. The power of the approach is demonstrated using two rRNA data sets: a mitochondrial rRNA set of 26 Mammalia, and a collection of 28S nuclear rRNAs representative of the five major echinoderm groups. PMID:19723687

  9. Accurate and efficient reconstruction of deep phylogenies from structured RNAs.

    PubMed

    Stocsits, Roman R; Letsch, Harald; Hertel, Jana; Misof, Bernhard; Stadler, Peter F

    2009-10-01

    Ribosomal RNA (rRNA) genes are probably the most frequently used data source in phylogenetic reconstruction. Individual columns of rRNA alignments are not independent as a consequence of their highly conserved secondary structures. Unless explicitly taken into account, these correlation can distort the phylogenetic signal and/or lead to gross overestimates of tree stability. Maximum likelihood and Bayesian approaches are of course amenable to using RNA-specific substitution models that treat conserved base pairs appropriately, but require accurate secondary structure models as input. So far, however, no accurate and easy-to-use tool has been available for computing structure-aware alignments and consensus structures that can deal with the large rRNAs. The RNAsalsa approach is designed to fill this gap. Capitalizing on the improved accuracy of pairwise consensus structures and informed by a priori knowledge of group-specific structural constraints, the tool provides both alignments and consensus structures that are of sufficient accuracy for routine phylogenetic analysis based on RNA-specific substitution models. The power of the approach is demonstrated using two rRNA data sets: a mitochondrial rRNA set of 26 Mammalia, and a collection of 28S nuclear rRNAs representative of the five major echinoderm groups. PMID:19723687

  10. Accurate phylogenetic classification of DNA fragments based onsequence composition

    SciTech Connect

    McHardy, Alice C.; Garcia Martin, Hector; Tsirigos, Aristotelis; Hugenholtz, Philip; Rigoutsos, Isidore

    2006-05-01

    Metagenome studies have retrieved vast amounts of sequenceout of a variety of environments, leading to novel discoveries and greatinsights into the uncultured microbial world. Except for very simplecommunities, diversity makes sequence assembly and analysis a verychallenging problem. To understand the structure a 5 nd function ofmicrobial communities, a taxonomic characterization of the obtainedsequence fragments is highly desirable, yet currently limited mostly tothose sequences that contain phylogenetic marker genes. We show that forclades at the rank of domain down to genus, sequence composition allowsthe very accurate phylogenetic 10 characterization of genomic sequence.We developed a composition-based classifier, PhyloPythia, for de novophylogenetic sequence characterization and have trained it on adata setof 340 genomes. By extensive evaluation experiments we show that themethodis accurate across all taxonomic ranks considered, even forsequences that originate fromnovel organisms and are as short as 1kb.Application to two metagenome datasets 15 obtained from samples ofphosphorus-removing sludge showed that the method allows the accurateclassification at genus level of most sequence fragments from thedominant populations, while at the same time correctly characterizingeven larger parts of the samples at higher taxonomic levels.

  11. Accurate estimation of sigma(exp 0) using AIRSAR data

    NASA Technical Reports Server (NTRS)

    Holecz, Francesco; Rignot, Eric

    1995-01-01

    During recent years signature analysis, classification, and modeling of Synthetic Aperture Radar (SAR) data as well as estimation of geophysical parameters from SAR data have received a great deal of interest. An important requirement for the quantitative use of SAR data is the accurate estimation of the backscattering coefficient sigma(exp 0). In terrain with relief variations radar signals are distorted due to the projection of the scene topography into the slant range-Doppler plane. The effect of these variations is to change the physical size of the scattering area, leading to errors in the radar backscatter values and incidence angle. For this reason the local incidence angle, derived from sensor position and Digital Elevation Model (DEM) data must always be considered. Especially in the airborne case, the antenna gain pattern can be an additional source of radiometric error, because the radar look angle is not known precisely as a result of the the aircraft motions and the local surface topography. Consequently, radiometric distortions due to the antenna gain pattern must also be corrected for each resolution cell, by taking into account aircraft displacements (position and attitude) and position of the backscatter element, defined by the DEM data. In this paper, a method to derive an accurate estimation of the backscattering coefficient using NASA/JPL AIRSAR data is presented. The results are evaluated in terms of geometric accuracy, radiometric variations of sigma(exp 0), and precision of the estimated forest biomass.

  12. Accurate Determination of Membrane Dynamics with Line-Scan FCS

    PubMed Central

    Ries, Jonas; Chiantia, Salvatore; Schwille, Petra

    2009-01-01

    Here we present an efficient implementation of line-scan fluorescence correlation spectroscopy (i.e., one-dimensional spatio-temporal image correlation spectroscopy) using a commercial laser scanning microscope, which allows the accurate measurement of diffusion coefficients and concentrations in biological lipid membranes within seconds. Line-scan fluorescence correlation spectroscopy is a calibration-free technique. Therefore, it is insensitive to optical artifacts, saturation, or incorrect positioning of the laser focus. In addition, it is virtually unaffected by photobleaching. Correction schemes for residual inhomogeneities and depletion of fluorophores due to photobleaching extend the applicability of line-scan fluorescence correlation spectroscopy to more demanding systems. This technique enabled us to measure accurate diffusion coefficients and partition coefficients of fluorescent lipids in phase-separating supported bilayers of three commonly used raft-mimicking compositions. Furthermore, we probed the temperature dependence of the diffusion coefficient in several model membranes, and in human embryonic kidney cell membranes not affected by temperature-induced optical aberrations. PMID:19254560

  13. Anisotropic Turbulence Modeling for Accurate Rod Bundle Simulations

    SciTech Connect

    Baglietto, Emilio

    2006-07-01

    An improved anisotropic eddy viscosity model has been developed for accurate predictions of the thermal hydraulic performances of nuclear reactor fuel assemblies. The proposed model adopts a non-linear formulation of the stress-strain relationship in order to include the reproduction of the anisotropic phenomena, and in combination with an optimized low-Reynolds-number formulation based on Direct Numerical Simulation (DNS) to produce correct damping of the turbulent viscosity in the near wall region. This work underlines the importance of accurate anisotropic modeling to faithfully reproduce the scale of the turbulence driven secondary flows inside the bundle subchannels, by comparison with various isothermal and heated experimental cases. The very low scale secondary motion is responsible for the increased turbulence transport which produces a noticeable homogenization of the velocity distribution and consequently of the circumferential cladding temperature distribution, which is of main interest in bundle design. Various fully developed bare bundles test cases are shown for different geometrical and flow conditions, where the proposed model shows clearly improved predictions, in close agreement with experimental findings, for regular as well as distorted geometries. Finally the applicability of the model for practical bundle calculations is evaluated through its application in the high-Reynolds form on coarse grids, with excellent results. (author)

  14. Exploring accurate Poisson–Boltzmann methods for biomolecular simulations

    PubMed Central

    Wang, Changhao; Wang, Jun; Cai, Qin; Li, Zhilin; Zhao, Hong-Kai; Luo, Ray

    2013-01-01

    Accurate and efficient treatment of electrostatics is a crucial step in computational analyses of biomolecular structures and dynamics. In this study, we have explored a second-order finite-difference numerical method to solve the widely used Poisson–Boltzmann equation for electrostatic analyses of realistic bio-molecules. The so-called immersed interface method was first validated and found to be consistent with the classical weighted harmonic averaging method for a diversified set of test biomolecules. The numerical accuracy and convergence behaviors of the new method were next analyzed in its computation of numerical reaction field grid potentials, energies, and atomic solvation forces. Overall similar convergence behaviors were observed as those by the classical method. Interestingly, the new method was found to deliver more accurate and better-converged grid potentials than the classical method on or nearby the molecular surface, though the numerical advantage of the new method is reduced when grid potentials are extrapolated to the molecular surface. Our exploratory study indicates the need for further improving interpolation/extrapolation schemes in addition to the developments of higher-order numerical methods that have attracted most attention in the field. PMID:24443709

  15. Mouse models of human AML accurately predict chemotherapy response.

    PubMed

    Zuber, Johannes; Radtke, Ina; Pardee, Timothy S; Zhao, Zhen; Rappaport, Amy R; Luo, Weijun; McCurrach, Mila E; Yang, Miao-Miao; Dolan, M Eileen; Kogan, Scott C; Downing, James R; Lowe, Scott W

    2009-04-01

    The genetic heterogeneity of cancer influences the trajectory of tumor progression and may underlie clinical variation in therapy response. To model such heterogeneity, we produced genetically and pathologically accurate mouse models of common forms of human acute myeloid leukemia (AML) and developed methods to mimic standard induction chemotherapy and efficiently monitor therapy response. We see that murine AMLs harboring two common human AML genotypes show remarkably diverse responses to conventional therapy that mirror clinical experience. Specifically, murine leukemias expressing the AML1/ETO fusion oncoprotein, associated with a favorable prognosis in patients, show a dramatic response to induction chemotherapy owing to robust activation of the p53 tumor suppressor network. Conversely, murine leukemias expressing MLL fusion proteins, associated with a dismal prognosis in patients, are drug-resistant due to an attenuated p53 response. Our studies highlight the importance of genetic information in guiding the treatment of human AML, functionally establish the p53 network as a central determinant of chemotherapy response in AML, and demonstrate that genetically engineered mouse models of human cancer can accurately predict therapy response in patients. PMID:19339691

  16. An accurate model potential for alkali neon systems.

    PubMed

    Zanuttini, D; Jacquet, E; Giglio, E; Douady, J; Gervais, B

    2009-12-01

    We present a detailed investigation of the ground and lowest excited states of M-Ne dimers, for M=Li, Na, and K. We show that the potential energy curves of these Van der Waals dimers can be obtained accurately by considering the alkali neon systems as one-electron systems. Following previous authors, the model describes the evolution of the alkali valence electron in the combined potentials of the alkali and neon cores by means of core polarization pseudopotentials. The key parameter for an accurate model is the M(+)-Ne potential energy curve, which was obtained by means of ab initio CCSD(T) calculation using a large basis set. For each MNe dimer, a systematic comparison with ab initio computation of the potential energy curve for the X, A, and B states shows the remarkable accuracy of the model. The vibrational analysis and the comparison with existing experimental data strengthens this conclusion and allows for a precise assignment of the vibrational levels. PMID:19968334

  17. Ultra-accurate collaborative information filtering via directed user similarity

    NASA Astrophysics Data System (ADS)

    Guo, Q.; Song, W.-J.; Liu, J.-G.

    2014-07-01

    A key challenge of the collaborative filtering (CF) information filtering is how to obtain the reliable and accurate results with the help of peers' recommendation. Since the similarities from small-degree users to large-degree users would be larger than the ones in opposite direction, the large-degree users' selections are recommended extensively by the traditional second-order CF algorithms. By considering the users' similarity direction and the second-order correlations to depress the influence of mainstream preferences, we present the directed second-order CF (HDCF) algorithm specifically to address the challenge of accuracy and diversity of the CF algorithm. The numerical results for two benchmark data sets, MovieLens and Netflix, show that the accuracy of the new algorithm outperforms the state-of-the-art CF algorithms. Comparing with the CF algorithm based on random walks proposed by Liu et al. (Int. J. Mod. Phys. C, 20 (2009) 285) the average ranking score could reach 0.0767 and 0.0402, which is enhanced by 27.3% and 19.1% for MovieLens and Netflix, respectively. In addition, the diversity, precision and recall are also enhanced greatly. Without relying on any context-specific information, tuning the similarity direction of CF algorithms could obtain accurate and diverse recommendations. This work suggests that the user similarity direction is an important factor to improve the personalized recommendation performance.

  18. An Accurate Temperature Correction Model for Thermocouple Hygrometers 1

    PubMed Central

    Savage, Michael J.; Cass, Alfred; de Jager, James M.

    1982-01-01

    Numerous water relation studies have used thermocouple hygrometers routinely. However, the accurate temperature correction of hygrometer calibration curve slopes seems to have been largely neglected in both psychrometric and dewpoint techniques. In the case of thermocouple psychrometers, two temperature correction models are proposed, each based on measurement of the thermojunction radius and calculation of the theoretical voltage sensitivity to changes in water potential. The first model relies on calibration at a single temperature and the second at two temperatures. Both these models were more accurate than the temperature correction models currently in use for four psychrometers calibrated over a range of temperatures (15-38°C). The model based on calibration at two temperatures is superior to that based on only one calibration. The model proposed for dewpoint hygrometers is similar to that for psychrometers. It is based on the theoretical voltage sensitivity to changes in water potential. Comparison with empirical data from three dewpoint hygrometers calibrated at four different temperatures indicates that these instruments need only be calibrated at, e.g. 25°C, if the calibration slopes are corrected for temperature. PMID:16662241

  19. An accurate temperature correction model for thermocouple hygrometers.

    PubMed

    Savage, M J; Cass, A; de Jager, J M

    1982-02-01

    Numerous water relation studies have used thermocouple hygrometers routinely. However, the accurate temperature correction of hygrometer calibration curve slopes seems to have been largely neglected in both psychrometric and dewpoint techniques.In the case of thermocouple psychrometers, two temperature correction models are proposed, each based on measurement of the thermojunction radius and calculation of the theoretical voltage sensitivity to changes in water potential. The first model relies on calibration at a single temperature and the second at two temperatures. Both these models were more accurate than the temperature correction models currently in use for four psychrometers calibrated over a range of temperatures (15-38 degrees C). The model based on calibration at two temperatures is superior to that based on only one calibration.The model proposed for dewpoint hygrometers is similar to that for psychrometers. It is based on the theoretical voltage sensitivity to changes in water potential. Comparison with empirical data from three dewpoint hygrometers calibrated at four different temperatures indicates that these instruments need only be calibrated at, e.g. 25 degrees C, if the calibration slopes are corrected for temperature. PMID:16662241

  20. Machine learning of parameters for accurate semiempirical quantum chemical calculations

    DOE PAGESBeta

    Dral, Pavlo O.; von Lilienfeld, O. Anatole; Thiel, Walter

    2015-04-14

    We investigate possible improvements in the accuracy of semiempirical quantum chemistry (SQC) methods through the use of machine learning (ML) models for the parameters. For a given class of compounds, ML techniques require sufficiently large training sets to develop ML models that can be used for adapting SQC parameters to reflect changes in molecular composition and geometry. The ML-SQC approach allows the automatic tuning of SQC parameters for individual molecules, thereby improving the accuracy without deteriorating transferability to molecules with molecular descriptors very different from those in the training set. The performance of this approach is demonstrated for the semiempiricalmore » OM2 method using a set of 6095 constitutional isomers C7H10O2, for which accurate ab initio atomization enthalpies are available. The ML-OM2 results show improved average accuracy and a much reduced error range compared with those of standard OM2 results, with mean absolute errors in atomization enthalpies dropping from 6.3 to 1.7 kcal/mol. They are also found to be superior to the results from specific OM2 reparameterizations (rOM2) for the same set of isomers. The ML-SQC approach thus holds promise for fast and reasonably accurate high-throughput screening of materials and molecules.« less

  1. Machine learning of parameters for accurate semiempirical quantum chemical calculations

    SciTech Connect

    Dral, Pavlo O.; von Lilienfeld, O. Anatole; Thiel, Walter

    2015-04-14

    We investigate possible improvements in the accuracy of semiempirical quantum chemistry (SQC) methods through the use of machine learning (ML) models for the parameters. For a given class of compounds, ML techniques require sufficiently large training sets to develop ML models that can be used for adapting SQC parameters to reflect changes in molecular composition and geometry. The ML-SQC approach allows the automatic tuning of SQC parameters for individual molecules, thereby improving the accuracy without deteriorating transferability to molecules with molecular descriptors very different from those in the training set. The performance of this approach is demonstrated for the semiempirical OM2 method using a set of 6095 constitutional isomers C7H10O2, for which accurate ab initio atomization enthalpies are available. The ML-OM2 results show improved average accuracy and a much reduced error range compared with those of standard OM2 results, with mean absolute errors in atomization enthalpies dropping from 6.3 to 1.7 kcal/mol. They are also found to be superior to the results from specific OM2 reparameterizations (rOM2) for the same set of isomers. The ML-SQC approach thus holds promise for fast and reasonably accurate high-throughput screening of materials and molecules.

  2. Accurate optical CD profiler based on specialized finite element method

    NASA Astrophysics Data System (ADS)

    Carrero, Jesus; Perçin, Gökhan

    2012-03-01

    As the semiconductor industry is moving to very low-k1 patterning solutions, the metrology problems facing process engineers are becoming much more complex. Choosing the right optical critical dimension (OCD) metrology technique is essential for bridging the metrology gap and achieving the required manufacturing volume throughput. The critical dimension scanning electron microscope (CD-SEM) measurement is usually distorted by the high aspect ratio of the photoresist and hard mask layers. CD-SEM measurements cease to correlate with complex three-dimensional profiles, such as the cases for double patterning and FinFETs, thus necessitating sophisticated, accurate and fast computational methods to bridge the gap. In this work, a suite of computational methods that complement advanced OCD equipment, and enabling them to operate at higher accuracies, are developed. In this article, a novel method for accurately modeling OCD profiles is presented. A finite element formulation in primal form is used to discretize the equations. The implementation uses specialized finite element spaces to solve Maxwell equations in two dimensions.

  3. Accurate interlaminar stress recovery from finite element analysis

    NASA Technical Reports Server (NTRS)

    Tessler, Alexander; Riggs, H. Ronald

    1994-01-01

    The accuracy and robustness of a two-dimensional smoothing methodology is examined for the problem of recovering accurate interlaminar shear stress distributions in laminated composite and sandwich plates. The smoothing methodology is based on a variational formulation which combines discrete least-squares and penalty-constraint functionals in a single variational form. The smoothing analysis utilizes optimal strains computed at discrete locations in a finite element analysis. These discrete strain data are smoothed with a smoothing element discretization, producing superior accuracy strains and their first gradients. The approach enables the resulting smooth strain field to be practically C1-continuous throughout the domain of smoothing, exhibiting superconvergent properties of the smoothed quantity. The continuous strain gradients are also obtained directly from the solution. The recovered strain gradients are subsequently employed in the integration o equilibrium equations to obtain accurate interlaminar shear stresses. The problem is a simply-supported rectangular plate under a doubly sinusoidal load. The problem has an exact analytic solution which serves as a measure of goodness of the recovered interlaminar shear stresses. The method has the versatility of being applicable to the analysis of rather general and complex structures built of distinct components and materials, such as found in aircraft design. For these types of structures, the smoothing is achieved with 'patches', each patch covering the domain in which the smoothed quantity is physically continuous.

  4. An Accurate and Dynamic Computer Graphics Muscle Model

    NASA Technical Reports Server (NTRS)

    Levine, David Asher

    1997-01-01

    A computer based musculo-skeletal model was developed at the University in the departments of Mechanical and Biomedical Engineering. This model accurately represents human shoulder kinematics. The result of this model is the graphical display of bones moving through an appropriate range of motion based on inputs of EMGs and external forces. The need existed to incorporate a geometric muscle model in the larger musculo-skeletal model. Previous muscle models did not accurately represent muscle geometries, nor did they account for the kinematics of tendons. This thesis covers the creation of a new muscle model for use in the above musculo-skeletal model. This muscle model was based on anatomical data from the Visible Human Project (VHP) cadaver study. Two-dimensional digital images from the VHP were analyzed and reconstructed to recreate the three-dimensional muscle geometries. The recreated geometries were smoothed, reduced, and sliced to form data files defining the surfaces of each muscle. The muscle modeling function opened these files during run-time and recreated the muscle surface. The modeling function applied constant volume limitations to the muscle and constant geometry limitations to the tendons.

  5. Accurate 3D quantification of the bronchial parameters in MDCT

    NASA Astrophysics Data System (ADS)

    Saragaglia, A.; Fetita, C.; Preteux, F.; Brillet, P. Y.; Grenier, P. A.

    2005-08-01

    The assessment of bronchial reactivity and wall remodeling in asthma plays a crucial role in better understanding such a disease and evaluating therapeutic responses. Today, multi-detector computed tomography (MDCT) makes it possible to perform an accurate estimation of bronchial parameters (lumen and wall areas) by allowing a quantitative analysis in a cross-section plane orthogonal to the bronchus axis. This paper provides the tools for such an analysis by developing a 3D investigation method which relies on 3D reconstruction of bronchial lumen and central axis computation. Cross-section images at bronchial locations interactively selected along the central axis are generated at appropriate spatial resolution. An automated approach is then developed for accurately segmenting the inner and outer bronchi contours on the cross-section images. It combines mathematical morphology operators, such as "connection cost", and energy-controlled propagation in order to overcome the difficulties raised by vessel adjacencies and wall irregularities. The segmentation accuracy was validated with respect to a 3D mathematically-modeled phantom of a pair bronchus-vessel which mimics the characteristics of real data in terms of gray-level distribution, caliber and orientation. When applying the developed quantification approach to such a model with calibers ranging from 3 to 10 mm diameter, the lumen area relative errors varied from 3.7% to 0.15%, while the bronchus area was estimated with a relative error less than 5.1%.

  6. Accurate and Precise Zinc Isotope Ratio Measurements in Urban Aerosols

    NASA Astrophysics Data System (ADS)

    Weiss, D.; Gioia, S. M. C. L.; Coles, B.; Arnold, T.; Babinski, M.

    2009-04-01

    We developed an analytical method and constrained procedural boundary conditions that enable accurate and precise Zn isotope ratio measurements in urban aerosols. We also demonstrate the potential of this new isotope system for air pollutant source tracing. The procedural blank is around 5 ng and significantly lower than published methods due to a tailored ion chromatographic separation. Accurate mass bias correction using external correction with Cu is limited to Zn sample content of approximately 50 ng due to the combined effect of blank contribution of Cu and Zn from the ion exchange procedure and the need to maintain a Cu/Zn ratio of approximately 1. Mass bias is corrected for by applying the common analyte internal standardization method approach. Comparison with other mass bias correction methods demonstrates the accuracy of the method. The average precision of δ66Zn determinations in aerosols is around 0.05 per mil per atomic mass unit. The method was tested on aerosols collected in Sao Paulo City, Brazil. The measurements reveal significant variations in δ66Zn ranging between -0.96 and -0.37 per mil in coarse and between -1.04 and 0.02 per mil in fine particular matter. This variability suggests that Zn isotopic compositions distinguish atmospheric sources. The isotopic light signature suggests traffic as the main source.

  7. More-Accurate Model of Flows in Rocket Injectors

    NASA Technical Reports Server (NTRS)

    Hosangadi, Ashvin; Chenoweth, James; Brinckman, Kevin; Dash, Sanford

    2011-01-01

    An improved computational model for simulating flows in liquid-propellant injectors in rocket engines has been developed. Models like this one are needed for predicting fluxes of heat in, and performances of, the engines. An important part of predicting performance is predicting fluctuations of temperature, fluctuations of concentrations of chemical species, and effects of turbulence on diffusion of heat and chemical species. Customarily, diffusion effects are represented by parameters known in the art as the Prandtl and Schmidt numbers. Prior formulations include ad hoc assumptions of constant values of these parameters, but these assumptions and, hence, the formulations, are inaccurate for complex flows. In the improved model, these parameters are neither constant nor specified in advance: instead, they are variables obtained as part of the solution. Consequently, this model represents the effects of turbulence on diffusion of heat and chemical species more accurately than prior formulations do, and may enable more-accurate prediction of mixing and flows of heat in rocket-engine combustion chambers. The model has been implemented within CRUNCH CFD, a proprietary computational fluid dynamics (CFD) computer program, and has been tested within that program. The model could also be implemented within other CFD programs.

  8. Novel dispersion tolerant interferometry method for accurate measurements of displacement

    NASA Astrophysics Data System (ADS)

    Bradu, Adrian; Maria, Michael; Leick, Lasse; Podoleanu, Adrian G.

    2015-05-01

    We demonstrate that the recently proposed master-slave interferometry method is able to provide true dispersion free depth profiles in a spectrometer-based set-up that can be used for accurate displacement measurements in sensing and optical coherence tomography. The proposed technique is based on correlating the channelled spectra produced by the linear camera in the spectrometer with previously recorded masks. As such technique is not based on Fourier transformations (FT), it does not require any resampling of data and is immune to any amounts of dispersion left unbalanced in the system. In order to prove the tolerance of technique to dispersion, different lengths of optical fiber are used in the interferometer to introduce dispersion and it is demonstrated that neither the sensitivity profile versus optical path difference (OPD) nor the depth resolution are affected. In opposition, it is shown that the classical FT based methods using calibrated data provide less accurate optical path length measurements and exhibit a quicker decays of sensitivity with OPD.

  9. Accurate Anharmonic IR Spectra from Integrated Cc/dft Approach

    NASA Astrophysics Data System (ADS)

    Barone, Vincenzo; Biczysko, Malgorzata; Bloino, Julien; Carnimeo, Ivan; Puzzarini, Cristina

    2014-06-01

    The recent implementation of the computation of infrared (IR) intensities beyond the double harmonic approximation [1] paved the route to routine calculations of infrared spectra for a wide set of molecular systems. Contrary to common beliefs, second-order perturbation theory is able to deliver results of high accuracy provided that anharmonic resonances are properly managed [1,2]. It has been already shown for several small closed- and open shell molecular systems that the differences between coupled cluster (CC) and DFT anharmonic wavenumbers are mainly due to the harmonic terms, paving the route to introduce effective yet accurate hybrid CC/DFT schemes [2]. In this work we present that hybrid CC/DFT models can be applied also to the IR intensities leading to the simulation of highly accurate fully anharmonic IR spectra for medium-size molecules, including ones of atmospheric interest, showing in all cases good agreement with experiment even in the spectral ranges where non-fundamental transitions are predominant[3]. [1] J. Bloino and V. Barone, J. Chem. Phys. 136, 124108 (2012) [2] V. Barone, M. Biczysko, J. Bloino, Phys. Chem. Chem. Phys., 16, 1759-1787 (2014) [3] I. Carnimeo, C. Puzzarini, N. Tasinato, P. Stoppa, A. P. Charmet, M. Biczysko, C. Cappelli and V. Barone, J. Chem. Phys., 139, 074310 (2013)

  10. Accurate measurements of dynamics and reproducibility in small genetic networks

    PubMed Central

    Dubuis, Julien O; Samanta, Reba; Gregor, Thomas

    2013-01-01

    Quantification of gene expression has become a central tool for understanding genetic networks. In many systems, the only viable way to measure protein levels is by immunofluorescence, which is notorious for its limited accuracy. Using the early Drosophila embryo as an example, we show that careful identification and control of experimental error allows for highly accurate gene expression measurements. We generated antibodies in different host species, allowing for simultaneous staining of four Drosophila gap genes in individual embryos. Careful error analysis of hundreds of expression profiles reveals that less than ∼20% of the observed embryo-to-embryo fluctuations stem from experimental error. These measurements make it possible to extract not only very accurate mean gene expression profiles but also their naturally occurring fluctuations of biological origin and corresponding cross-correlations. We use this analysis to extract gap gene profile dynamics with ∼1 min accuracy. The combination of these new measurements and analysis techniques reveals a twofold increase in profile reproducibility owing to a collective network dynamics that relays positional accuracy from the maternal gradients to the pair-rule genes. PMID:23340845

  11. Quality metric for accurate overlay control in <20nm nodes

    NASA Astrophysics Data System (ADS)

    Klein, Dana; Amit, Eran; Cohen, Guy; Amir, Nuriel; Har-Zvi, Michael; Huang, Chin-Chou Kevin; Karur-Shanmugam, Ramkumar; Pierson, Bill; Kato, Cindy; Kurita, Hiroyuki

    2013-04-01

    The semiconductor industry is moving toward 20nm nodes and below. As the Overlay (OVL) budget is getting tighter at these advanced nodes, the importance in the accuracy in each nanometer of OVL error is critical. When process owners select OVL targets and methods for their process, they must do it wisely; otherwise the reported OVL could be inaccurate, resulting in yield loss. The same problem can occur when the target sampling map is chosen incorrectly, consisting of asymmetric targets that will cause biased correctable terms and a corrupted wafer. Total measurement uncertainty (TMU) is the main parameter that process owners use when choosing an OVL target per layer. Going towards the 20nm nodes and below, TMU will not be enough for accurate OVL control. KLA-Tencor has introduced a quality score named `Qmerit' for its imaging based OVL (IBO) targets, which is obtained on the-fly for each OVL measurement point in X & Y. This Qmerit score will enable the process owners to select compatible targets which provide accurate OVL values for their process and thereby improve their yield. Together with K-T Analyzer's ability to detect the symmetric targets across the wafer and within the field, the Archer tools will continue to provide an independent, reliable measurement of OVL error into the next advanced nodes, enabling fabs to manufacture devices that meet their tight OVL error budgets.

  12. Accurate tremor locations from coherent S and P waves

    NASA Astrophysics Data System (ADS)

    Armbruster, John G.; Kim, Won-Young; Rubin, Allan M.

    2014-06-01

    Nonvolcanic tremor is an important component of the slow slip processes which load faults from below, but accurately locating tremor has proven difficult because tremor rarely contains clear P or S wave arrivals. Here we report the observation of coherence in the shear and compressional waves of tremor at widely separated stations which allows us to detect and accurately locate tremor events. An event detector using data from two stations sees the onset of tremor activity in the Cascadia tremor episodes of February 2003, July 2004, and September 2005 and confirms the previously reported south to north migration of the tremor. Event detectors using data from three and four stations give Sand P arrival times of high accuracy. The hypocenters of the tremor events fall at depths of ˜30 to ˜40 km and define a narrow plane dipping at a shallow angle to the northeast, consistent with the subducting plate interface. The S wave polarizations and P wave first motions define a source mechanism in agreement with the northeast convergence seen in geodetic observations of slow slip. Tens of thousands of locations determined by constraining the events to the plate interface show tremor sources highly clustered in space with a strongly similar pattern of sources in the three episodes examined. The deeper sources generate tremor in minor episodes as well. The extent to which the narrow bands of tremor sources overlap between the three major episodes suggests relative epicentral location errors as small as 1-2 km.

  13. Individual Differences in Accurately Judging Personality From Text.

    PubMed

    Hall, Judith A; Goh, Jin X; Mast, Marianne Schmid; Hagedorn, Christian

    2016-08-01

    This research examines correlates of accuracy in judging Big Five traits from first-person text excerpts. Participants in six studies were recruited from psychology courses or online. In each study, participants performed a task of judging personality from text and performed other ability tasks and/or filled out questionnaires. Participants who were more accurate in judging personality from text were more likely to be female; had personalities that were more agreeable, conscientious, and feminine, and less neurotic and dominant (all controlling for participant gender); scored higher on empathic concern; self-reported more interest in, and attentiveness to, people's personalities in their daily lives; and reported reading more for pleasure, especially fiction. Accuracy was not associated with SAT scores but had a significant relation to vocabulary knowledge. Accuracy did not correlate with tests of judging personality and emotion based on audiovisual cues. This research is the first to address individual differences in accurate judgment of personality from text, thus adding to the literature on correlates of the good judge of personality. PMID:25720617

  14. A general, accurate procedure for calculating molecular interaction force.

    PubMed

    Yang, Pinghai; Qian, Xiaoping

    2009-09-15

    The determination of molecular interaction forces, e.g., van der Waals force, between macroscopic bodies is of fundamental importance for understanding sintering, adhesion and fracture processes. In this paper, we develop an accurate, general procedure for van der Waals force calculation. This approach extends a surface formulation that converts a six-dimensional (6D) volume integral into a 4D surface integral for the force calculation. It uses non-uniform rational B-spline (NURBS) surfaces to represent object surfaces. Surface integrals are then done on the parametric domain of the NURBS surfaces. It has combined advantages of NURBS surface representation and surface formulation, including (1) molecular interactions between arbitrary-shaped objects can be represented and evaluated by the NURBS model further common geometries such as spheres, cones, planes can be represented exactly and interaction forces are thus calculated accurately; (2) calculation efficiency is improved by converting the volume integral to the surface integral. This approach is implemented and validated via its comparison with analytical solutions for simple geometries. Calculation of van der Waals force between complex geometries with surface roughness is also demonstrated. A tutorial on the NURBS approach is given in Appendix A. PMID:19596335

  15. Accurate Evaluation Method of Molecular Binding Affinity from Fluctuation Frequency

    NASA Astrophysics Data System (ADS)

    Hoshino, Tyuji; Iwamoto, Koji; Ode, Hirotaka; Ohdomari, Iwao

    2008-05-01

    Exact estimation of the molecular binding affinity is significantly important for drug discovery. The energy calculation is a direct method to compute the strength of the interaction between two molecules. This energetic approach is, however, not accurate enough to evaluate a slight difference in binding affinity when distinguishing a prospective substance from dozens of candidates for medicine. Hence more accurate estimation of drug efficacy in a computer is currently demanded. Previously we proposed a concept of estimating molecular binding affinity, focusing on the fluctuation at an interface between two molecules. The aim of this paper is to demonstrate the compatibility between the proposed computational technique and experimental measurements, through several examples for computer simulations of an association of human immunodeficiency virus type-1 (HIV-1) protease and its inhibitor (an example for a drug-enzyme binding), a complexation of an antigen and its antibody (an example for a protein-protein binding), and a combination of estrogen receptor and its ligand chemicals (an example for a ligand-receptor binding). The proposed affinity estimation has proven to be a promising technique in the advanced stage of the discovery and the design of drugs.

  16. Isomerism of Cyanomethanimine: Accurate Structural, Energetic, and Spectroscopic Characterization.

    PubMed

    Puzzarini, Cristina

    2015-11-25

    The structures, relative stabilities, and rotational and vibrational parameters of the Z-C-, E-C-, and N-cyanomethanimine isomers have been evaluated using state-of-the-art quantum-chemical approaches. Equilibrium geometries have been calculated by means of a composite scheme based on coupled-cluster calculations that accounts for the extrapolation to the complete basis set limit and core-correlation effects. The latter approach is proved to provide molecular structures with an accuracy of 0.001-0.002 Å and 0.05-0.1° for bond lengths and angles, respectively. Systematically extrapolated ab initio energies, accounting for electron correlation through coupled-cluster theory, including up to single, double, triple, and quadruple excitations, and corrected for core-electron correlation and anharmonic zero-point vibrational energy, have been used to accurately determine relative energies and the Z-E isomerization barrier with an accuracy of about 1 kJ/mol. Vibrational and rotational spectroscopic parameters have been investigated by means of hybrid schemes that allow us to obtain rotational constants accurate to about a few megahertz and vibrational frequencies with a mean absolute error of ∼1%. Where available, for all properties considered, a very good agreement with experimental data has been observed. PMID:26529434

  17. Reverse radiance: a fast accurate method for determining luminance

    NASA Astrophysics Data System (ADS)

    Moore, Kenneth E.; Rykowski, Ronald F.; Gangadhara, Sanjay

    2012-10-01

    Reverse ray tracing from a region of interest backward to the source has long been proposed as an efficient method of determining luminous flux. The idea is to trace rays only from where the final flux needs to be known back to the source, rather than tracing in the forward direction from the source outward to see where the light goes. Once the reverse ray reaches the source, the radiance the equivalent forward ray would have represented is determined and the resulting flux computed. Although reverse ray tracing is conceptually simple, the method critically depends upon an accurate source model in both the near and far field. An overly simplified source model, such as an ideal Lambertian surface substantially detracts from the accuracy and thus benefit of the method. This paper will introduce an improved method of reverse ray tracing that we call Reverse Radiance that avoids assumptions about the source properties. The new method uses measured data from a Source Imaging Goniometer (SIG) that simultaneously measures near and far field luminous data. Incorporating this data into a fast reverse ray tracing integration method yields fast, accurate data for a wide variety of illumination problems.

  18. Accurate camera calibration method specialized for virtual studios

    NASA Astrophysics Data System (ADS)

    Okubo, Hidehiko; Yamanouchi, Yuko; Mitsumine, Hideki; Fukaya, Takashi; Inoue, Seiki

    2008-02-01

    Virtual studio is a popular technology for TV programs, that makes possible to synchronize computer graphics (CG) to realshot image in camera motion. Normally, the geometrical matching accuracy between CG and realshot image is not expected so much on real-time system, we sometimes compromise on directions, not to come out the problem. So we developed the hybrid camera calibration method and CG generating system to achieve the accurate geometrical matching of CG and realshot on virtual studio. Our calibration method is intended for the camera system on platform and tripod with rotary encoder, that can measure pan/tilt angles. To solve the camera model and initial pose, we enhanced the bundle adjustment algorithm to fit the camera model, using pan/tilt data as known parameters, and optimizing all other parameters invariant against pan/tilt value. This initialization yields high accurate camera position and orientation consistent with any pan/tilt values. Also we created CG generator implemented the lens distortion function with GPU programming. By applying the lens distortion parameters obtained by camera calibration process, we could get fair compositing results.

  19. Simple and accurate optical height sensor for wafer inspection systems

    NASA Astrophysics Data System (ADS)

    Shimura, Kei; Nakai, Naoya; Taniguchi, Koichi; Itoh, Masahide

    2016-02-01

    An accurate method for measuring the wafer surface height is required for wafer inspection systems to adjust the focus of inspection optics quickly and precisely. A method for projecting a laser spot onto the wafer surface obliquely and for detecting its image displacement using a one-dimensional position-sensitive detector is known, and a variety of methods have been proposed for improving the accuracy by compensating the measurement error due to the surface patterns. We have developed a simple and accurate method in which an image of a reticle with eight slits is projected on the wafer surface and its reflected image is detected using an image sensor. The surface height is calculated by averaging the coordinates of the images of the slits in both the two directions in the captured image. Pattern-related measurement error was reduced by applying the coordinates averaging to the multiple-slit-projection method. Accuracy of better than 0.35 μm was achieved for a patterned wafer at the reference height and ±0.1 mm from the reference height in a simple configuration.

  20. A fast and accurate decoder for underwater acoustic telemetry

    NASA Astrophysics Data System (ADS)

    Ingraham, J. M.; Deng, Z. D.; Li, X.; Fu, T.; McMichael, G. A.; Trumbo, B. A.

    2014-07-01

    The Juvenile Salmon Acoustic Telemetry System, developed by the U.S. Army Corps of Engineers, Portland District, has been used to monitor the survival of juvenile salmonids passing through hydroelectric facilities in the Federal Columbia River Power System. Cabled hydrophone arrays deployed at dams receive coded transmissions sent from acoustic transmitters implanted in fish. The signals' time of arrival on different hydrophones is used to track fish in 3D. In this article, a new algorithm that decodes the received transmissions is described and the results are compared to results for the previous decoding algorithm. In a laboratory environment, the new decoder was able to decode signals with lower signal strength than the previous decoder, effectively increasing decoding efficiency and range. In field testing, the new algorithm decoded significantly more signals than the previous decoder and three-dimensional tracking experiments showed that the new decoder's time-of-arrival estimates were accurate. At multiple distances from hydrophones, the new algorithm tracked more points more accurately than the previous decoder. The new algorithm was also more than 10 times faster, which is critical for real-time applications on an embedded system.

  1. A fast and accurate decoder for underwater acoustic telemetry.

    PubMed

    Ingraham, J M; Deng, Z D; Li, X; Fu, T; McMichael, G A; Trumbo, B A

    2014-07-01

    The Juvenile Salmon Acoustic Telemetry System, developed by the U.S. Army Corps of Engineers, Portland District, has been used to monitor the survival of juvenile salmonids passing through hydroelectric facilities in the Federal Columbia River Power System. Cabled hydrophone arrays deployed at dams receive coded transmissions sent from acoustic transmitters implanted in fish. The signals' time of arrival on different hydrophones is used to track fish in 3D. In this article, a new algorithm that decodes the received transmissions is described and the results are compared to results for the previous decoding algorithm. In a laboratory environment, the new decoder was able to decode signals with lower signal strength than the previous decoder, effectively increasing decoding efficiency and range. In field testing, the new algorithm decoded significantly more signals than the previous decoder and three-dimensional tracking experiments showed that the new decoder's time-of-arrival estimates were accurate. At multiple distances from hydrophones, the new algorithm tracked more points more accurately than the previous decoder. The new algorithm was also more than 10 times faster, which is critical for real-time applications on an embedded system. PMID:25085162

  2. Accurate Computation of Survival Statistics in Genome-Wide Studies

    PubMed Central

    Vandin, Fabio; Papoutsaki, Alexandra; Raphael, Benjamin J.; Upfal, Eli

    2015-01-01

    A key challenge in genomics is to identify genetic variants that distinguish patients with different survival time following diagnosis or treatment. While the log-rank test is widely used for this purpose, nearly all implementations of the log-rank test rely on an asymptotic approximation that is not appropriate in many genomics applications. This is because: the two populations determined by a genetic variant may have very different sizes; and the evaluation of many possible variants demands highly accurate computation of very small p-values. We demonstrate this problem for cancer genomics data where the standard log-rank test leads to many false positive associations between somatic mutations and survival time. We develop and analyze a novel algorithm, Exact Log-rank Test (ExaLT), that accurately computes the p-value of the log-rank statistic under an exact distribution that is appropriate for any size populations. We demonstrate the advantages of ExaLT on data from published cancer genomics studies, finding significant differences from the reported p-values. We analyze somatic mutations in six cancer types from The Cancer Genome Atlas (TCGA), finding mutations with known association to survival as well as several novel associations. In contrast, standard implementations of the log-rank test report dozens-hundreds of likely false positive associations as more significant than these known associations. PMID:25950620

  3. Learning fast accurate movements requires intact frontostriatal circuits

    PubMed Central

    Shabbott, Britne; Ravindran, Roshni; Schumacher, Joseph W.; Wasserman, Paula B.; Marder, Karen S.; Mazzoni, Pietro

    2013-01-01

    The basal ganglia are known to play a crucial role in movement execution, but their importance for motor skill learning remains unclear. Obstacles to our understanding include the lack of a universally accepted definition of motor skill learning (definition confound), and difficulties in distinguishing learning deficits from execution impairments (performance confound). We studied how healthy subjects and subjects with a basal ganglia disorder learn fast accurate reaching movements. We addressed the definition and performance confounds by: (1) focusing on an operationally defined core element of motor skill learning (speed-accuracy learning), and (2) using normal variation in initial performance to separate movement execution impairment from motor learning abnormalities. We measured motor skill learning as performance improvement in a reaching task with a speed-accuracy trade-off. We compared the performance of subjects with Huntington's disease (HD), a neurodegenerative basal ganglia disorder, to that of premanifest carriers of the HD mutation and of control subjects. The initial movements of HD subjects were less skilled (slower and/or less accurate) than those of control subjects. To factor out these differences in initial execution, we modeled the relationship between learning and baseline performance in control subjects. Subjects with HD exhibited a clear learning impairment that was not explained by differences in initial performance. These results support a role for the basal ganglia in both movement execution and motor skill learning. PMID:24312037

  4. Accurate eye center location through invariant isocentric patterns.

    PubMed

    Valenti, Roberto; Gevers, Theo

    2012-09-01

    Locating the center of the eyes allows for valuable information to be captured and used in a wide range of applications. Accurate eye center location can be determined using commercial eye-gaze trackers, but additional constraints and expensive hardware make these existing solutions unattractive and impossible to use on standard (i.e., visible wavelength), low-resolution images of eyes. Systems based solely on appearance are proposed in the literature, but their accuracy does not allow us to accurately locate and distinguish eye centers movements in these low-resolution settings. Our aim is to bridge this gap by locating the center of the eye within the area of the pupil on low-resolution images taken from a webcam or a similar device. The proposed method makes use of isophote properties to gain invariance to linear lighting changes (contrast and brightness), to achieve in-plane rotational invariance, and to keep low-computational costs. To further gain scale invariance, the approach is applied to a scale space pyramid. In this paper, we extensively test our approach for its robustness to changes in illumination, head pose, scale, occlusion, and eye rotation. We demonstrate that our system can achieve a significant improvement in accuracy over state-of-the-art techniques for eye center location in standard low-resolution imagery. PMID:22813958

  5. The New Global Health

    PubMed Central

    Simone, Patricia M.; Davison, Veronica; Slutsker, Laurence

    2013-01-01

    Global health reflects the realities of globalization, including worldwide dissemination of infectious and noninfectious public health risks. Global health architecture is complex and better coordination is needed between multiple organizations. Three overlapping themes determine global health action and prioritization: development, security, and public health. These themes play out against a background of demographic change, socioeconomic development, and urbanization. Infectious diseases remain critical factors, but are no longer the major cause of global illness and death. Traditional indicators of public health, such as maternal and infant mortality rates no longer describe the health status of whole societies; this change highlights the need for investment in vital registration and disease-specific reporting. Noncommunicable diseases, injuries, and mental health will require greater attention from the world in the future. The new global health requires broader engagement by health organizations and all countries for the objectives of health equity, access, and coverage as priorities beyond the Millennium Development Goals are set. PMID:23876365

  6. Globalization, culture and psychology.

    PubMed

    Melluish, Steve

    2014-10-01

    This article outlines the cultural and psychological effects of globalization. It looks at the impact of globalization on identity; ideas of privacy and intimacy; the way we understand and perceive psychological distress; and the development of the profession of psychology around the world. The article takes a critical perspective on globalization, seeing it as aligned with the spread of neoliberal capitalism, a tendency towards cultural homogenization, the imposition of dominant 'global north' ideas and the resultant growing inequalities in health and well-being. However, it also argues that the increased interconnectedness created by globalization allows for greater acknowledgement of our common humanity and for collective efforts to be developed to tackle what are increasingly global problems. This requires the development of more nuanced understandings of cultural differences and of indigenous psychologies. PMID:25343628

  7. Global health for a globally minded president.

    PubMed

    Daulaire, Nils

    2009-01-01

    President-elect Barack Obama can build on historic initiatives championed by his predecessor in global AIDS and malaria. These should serve as the platform for a more comprehensive and evidence-based set of activities aimed at addressing the major causes of ill health and instability in low-income countries. Obama should launch a new Global Family Health Action Plan aimed at saving the lives of six million children and women annually in impoverished nations. Existing policies driven by U.S. domestic ideological battles, particularly those relating to sexual and reproductive health, should be revised and brought into line with solid science and evidence from the field. PMID:19151008

  8. Global water cycle

    NASA Technical Reports Server (NTRS)

    Robertson, Franklin; Goodman, Steven J.; Christy, John R.; Fitzjarrald, Daniel E.; Chou, Shi-Hung; Crosson, William; Wang, Shouping; Ramirez, Jorge

    1993-01-01

    This research is the MSFC component of a joint MSFC/Pennsylvania State University Eos Interdisciplinary Investigation on the global water cycle extension across the earth sciences. The primary long-term objective of this investigation is to determine the scope and interactions of the global water cycle with all components of the Earth system and to understand how it stimulates and regulates change on both global and regional scales. Significant accomplishments in the past year are presented and include the following: (1) water vapor variability; (2) multi-phase water analysis; (3) global modeling; and (4) optimal precipitation and stream flow analysis and hydrologic processes.

  9. NASA Global Hawk Overview

    NASA Technical Reports Server (NTRS)

    Naftel, Chris

    2014-01-01

    The NASA Global Hawk Project is supporting Earth Science research customers. These customers include: US Government agencies, civilian organizations, and universities. The combination of the Global Hawks range, endurance, altitude, payload power, payload volume and payload weight capabilities separates the Global Hawk platform from all other platforms available to the science community. This presentation includes an overview of the concept of operations and an overview of the completed science campaigns. In addition, the future science plans, using the NASA Global Hawk System, will be presented.

  10. Seasonal And Regional Differentiation Of Bio-Optical Properties Within The North Polar Atlantic

    NASA Technical Reports Server (NTRS)

    Stramska, Malgorzata; Stramski, Dariusz; Kaczmarek, Slawomir; Allison, David B.; Schwarz, Jill

    2005-01-01

    Using data collected during spring and summer seasons in the north polar Atlantic we examined the variability of the spectral absorption, a(lambda), and backscattering, b(sub b)(lambda), coefficients of surface waters and its relation to phytoplankton pigment concentration and composition. For a given chlorophyll a concentration (TChla), the concentrations of photosynthetic carotenoids (PSC), photoprotective carotenoids (PPC), and total accessory pigments (AP) were consistently lower in spring than in summer. The chlorophyll-specific absorption coefficients of phytoplankton and total particulate matter were also lower in spring, which can be partly attributed to lower proportions of PPC, PSC, and AP in spring. The spring values of the green-to-blue band ratio of the absorption coefficient were higher than the summer ratios. The blue-to-green ratios of backscattering coefficient were also higher in spring. The higher b(sub b) values and lower blue-to-green b(sub b) ratios in summer were likely associated with higher concentrations of detrital particles in summer compared to spring. Because the product of the green-to-blue absorption ratio and the blue-to-green backscattering ratio is a proxy for the blue-to-green ratio of remote-sensing reflectance, we conclude that the performance of ocean color band-ratio algorithms for estimating pigments in the north polar Atlantic is significantly affected by seasonal shifts in the relationships between absorption and TChla as well as between backscattering and TChla. Intriguingly, however, fairly good estimate of the particulate beam attenuation coefficient at 660 nm (potential measure of total particulate matter or particulate organic carbon concentration) can be obtained by applying a single blue-to-green band-ratio algorithm for both spring and summer seasons.

  11. Time dependent bio-optical and temperature measurements beneath Arctic pack ice

    NASA Astrophysics Data System (ADS)

    Hill, V. J.; Steele, M.; Light, B.

    2014-12-01

    As part of the Arctic Observing Network, a new ice-tethered buoy has been developed for monitoring under-ice light and temperature fields. A 20 to 50 m string supports sensors both within and below the ice for the collection of hourly estimates of vertically resolved downwelling irradiance (412, 443, 555 nm and PAR), temperature, chlorophyll a (Chl a) backscatter, and colored dissolved organic material (CDOM) fluorescence. Two buoys are currently operating. Buoy 1 was deployed in the Beaufort Sea in March 2014 and buoy 2 was deployed at the Barneo ice camp in collaboration with the North Pole Environmental observatory in April 2014. At both locations, attenuation of light in the uppermost 20 - 50 m of the water column was dominated by CDOM in the early spring. Buoy 1 drifted into the Chukchi Sea in June and experienced a switch from CDOM to phytoplankton dominated absorption. Buoy 2 has continued to drift south, but remains in the central basin. It has moved into water with reduced light attenuation properties, indicating low CDOM and low Chl a concentrations. Both buoys have observed water column temperature increases without associated increases in absorbed energy, indicating proximal open water. These buoys offer a unique opportunity to observe the seasonal evolution of the light field and associated warming of the upper water column in ice-covered seas.

  12. Advances in Bio-Optical Imaging for the Diagnosis of Early Oral Cancer

    PubMed Central

    Olivo, Malini; Bhuvaneswari, Ramaswamy; Keogh, Ivan

    2011-01-01

    Oral cancer is among the most common malignancies worldwide, therefore early detection and treatment is imperative. The 5-year survival rate has remained at a dismal 50% for the past several decades. The main reason for the poor survival rate is the fact that most of the oral cancers, despite the general accessibility of the oral cavity, are not diagnosed until the advanced stage. Early detection of the oral tumors and its precursor lesions may be the most effective means to improve clinical outcome and cure most patients. One of the emerging technologies is the use of non-invasive in vivo tissue imaging to capture the molecular changes at high-resolution to improve the detection capability of early stage disease. This review will discuss the use of optical probes and highlight the role of optical imaging such as autofluorescence, fluorescence diagnosis (FD), laser confocal endomicroscopy (LCE), surface enhanced Raman spectroscopy (SERS), optical coherence tomography (OCT) and confocal reflectance microscopy (CRM) in early oral cancer detection. FD is a promising method to differentiate cancerous lesions from benign, thus helping in the determination of adequate resolution of surgical resection margin. LCE offers in vivo cellular imaging of tissue structures from surface to subsurface layers and has demonstrated the potential to be used as a minimally invasive optical biopsy technique for early diagnosis of oral cancer lesions. SERS was able to differentiate between normal and oral cancer patients based on the spectra acquired from saliva of patients. OCT has been used to visualize the detailed histological features of the oral lesions with an imaging depth down to 2–3 mm. CRM is an optical tool to noninvasively image tissue with near histological resolution. These comprehensive diagnostic modalities can also be used to define surgical margin and to provide a direct assessment of the therapeutic effectiveness. PMID:24310585

  13. Bio-optics based sensation imaging for breast tumor detection using tissue characterization.

    PubMed

    Lee, Jong-Ha; Kim, Yoon Nyun; Park, Hee-Jun

    2015-01-01

    The tissue inclusion parameter estimation method is proposed to measure the stiffness as well as geometric parameters. The estimation is performed based on the tactile data obtained at the surface of the tissue using an optical tactile sensation imaging system (TSIS). A forward algorithm is designed to comprehensively predict the tactile data based on the mechanical properties of tissue inclusion using finite element modeling (FEM). This forward information is used to develop an inversion algorithm that will be used to extract the size, depth, and Young's modulus of a tissue inclusion from the tactile data. We utilize the artificial neural network (ANN) for the inversion algorithm. The proposed estimation method was validated by a realistic tissue phantom with stiff inclusions. The experimental results showed that the proposed estimation method can measure the size, depth, and Young's modulus of a tissue inclusion with 0.58%, 3.82%, and 2.51% relative errors, respectively. The obtained results prove that the proposed method has potential to become a useful screening and diagnostic method for breast cancer. PMID:25785306

  14. Bio-Optics Based Sensation Imaging for Breast Tumor Detection Using Tissue Characterization

    PubMed Central

    Lee, Jong-Ha; Kim, Yoon Nyun; Park, Hee-Jun

    2015-01-01

    The tissue inclusion parameter estimation method is proposed to measure the stiffness as well as geometric parameters. The estimation is performed based on the tactile data obtained at the surface of the tissue using an optical tactile sensation imaging system (TSIS). A forward algorithm is designed to comprehensively predict the tactile data based on the mechanical properties of tissue inclusion using finite element modeling (FEM). This forward information is used to develop an inversion algorithm that will be used to extract the size, depth, and Young's modulus of a tissue inclusion from the tactile data. We utilize the artificial neural network (ANN) for the inversion algorithm. The proposed estimation method was validated by a realistic tissue phantom with stiff inclusions. The experimental results showed that the proposed estimation method can measure the size, depth, and Young's modulus of a tissue inclusion with 0.58%, 3.82%, and 2.51% relative errors, respectively. The obtained results prove that the proposed method has potential to become a useful screening and diagnostic method for breast cancer. PMID:25785306

  15. Advances in bio-optical imaging for the diagnosis of early oral cancer.

    PubMed

    Olivo, Malini; Bhuvaneswari, Ramaswamy; Keogh, Ivan

    2011-01-01

    Oral cancer is among the most common malignancies worldwide, therefore early detection and treatment is imperative. The 5-year survival rate has remained at a dismal 50% for the past several decades. The main reason for the poor survival rate is the fact that most of the oral cancers, despite the general accessibility of the oral cavity, are not diagnosed until the advanced stage. Early detection of the oral tumors and its precursor lesions may be the most effective means to improve clinical outcome and cure most patients. One of the emerging technologies is the use of non-invasive in vivo tissue imaging to capture the molecular changes at high-resolution to improve the detection capability of early stage disease. This review will discuss the use of optical probes and highlight the role of optical imaging such as autofluorescence, fluorescence diagnosis (FD), laser confocal endomicroscopy (LCE), surface enhanced Raman spectroscopy (SERS), optical coherence tomography (OCT) and confocal reflectance microscopy (CRM) in early oral cancer detection. FD is a promising method to differentiate cancerous lesions from benign, thus helping in the determination of adequate resolution of surgical resection margin. LCE offers in vivo cellular imaging of tissue structures from surface to subsurface layers and has demonstrated the potential to be used as a minimally invasive optical biopsy technique for early diagnosis of oral cancer lesions. SERS was able to differentiate between normal and oral cancer patients based on the spectra acquired from saliva of patients. OCT has been used to visualize the detailed histological features of the oral lesions with an imaging depth down to 2-3 mm. CRM is an optical tool to noninvasively image tissue with near histological resolution. These comprehensive diagnostic modalities can also be used to define surgical margin and to provide a direct assessment of the therapeutic effectiveness. PMID:24310585

  16. Bio-Optical and Remote Sensing Observations in Chesapeake Bay. Chapter 7

    NASA Technical Reports Server (NTRS)

    Harding, Lawrence W., Jr.; Magnuson, Andrea

    2003-01-01

    The high temporal and spatial resolution of satellite ocean color observations will prove invaluable for monitoring the health of coastal ecosystems where physical and biological variability demands sampling scales beyond that possible by ship. However, ocean color remote sensing of Case 2 waters is a challenging undertaking due to the optical complexity of the water. The focus of this SIMBIOS support has been to provide in situ optical measurements from Chesapeake Bay (CB) and adjacent mid-Atlantic bight (MAB) waters for use in algorithm development and validation efforts to improve the satellite retrieval of chlorophyll (chl a) in Case 2 waters. CB provides a valuable site for validation of data from ocean color sensors for a number of reasons. First, the physical dimensions of the Bay (> 6,500 km2) make retrievals from satellites with a spatial resolution of approx. 1 km (i.e., SeaWiFS) or less (i.e., MODIS) reasonable for most of the ecosystem. Second, CB is highly influenced by freshwater flow from major rivers, making it a classic Case 2 water body with significant concentrations of chlorophyll, particulates and chromophoric dissolved organic matter (CDOM) that highly impact the shape of reflectance spectra.

  17. Seasonal and regional differentiation of bio-optical properties within the north polar Atlantic

    NASA Astrophysics Data System (ADS)

    Stramska, Malgorzata; Stramski, Dariusz; Kaczmarek, SłAwomir; Allison, David B.; Schwarz, Jill

    2006-08-01

    Using field data from the north polar Atlantic, we examined seasonal variability of the spectral absorption, a(λ), and backscattering, bb(λ), coefficients of surface waters in relation to phytoplankton pigments. For a given chlorophyll a concentration, the concentrations of accessory pigments were lower in spring than in summer. This effect contributed to lower chlorophyll-specific absorption of phytoplankton and total particulate matter in spring. The spring values of the green-to-blue band ratio of a(λ) were higher than the summer ratios. The blue-to-green ratios of bb(λ) were also higher in spring. The higher bb values and lower blue-to-green bb ratios in summer were likely associated with higher concentrations of detrital particles in summer compared to spring. Because the product of these band ratios of a and bb is a proxy for the blue-to-green ratio of remote-sensing reflectance, the performance of ocean color band-ratio algorithms for estimating pigments is significantly affected by seasonal shifts in the relationships between absorption, backscattering, and chlorophyll a. Our results suggest that the algorithm for the spring season would predict chlorophyll a that is higher by as much as a factor of 4-6 compared to that predicted from the summer algorithm. This indicates a need for a seasonal approach in the north polar Atlantic. However, we also found that a fairly good estimate of the particulate beam attenuation coefficient at 660 nm (a proxy for total particulate matter or particulate organic carbon concentration) can be obtained by applying a single blue-to-green band-ratio algorithm regardless of the season.

  18. Time-accurate Navier-Stokes calculations with multigrid acceleration

    NASA Technical Reports Server (NTRS)

    Melson, N. D.; Sanetrik, Mark D.; Atkins, Harold L.

    1993-01-01

    An efficient method for calculating unsteady flows is presented, with emphasis on a modified version of the thin-layer Navier-Stokes equations. Fourier stability analysis is used to illustrate the effect of treating the source term implicitly instead of explicity, as well as to illustrate other algorithmic choices. A 2D circular cylinder (with a Reynolds number of 1200 and a Mach number of 0.3) is calculated. The present scheme requires only about 10 percent of the computer time required by global minimum time stepping.

  19. The KFM, A Homemade Yet Accurate and Dependable Fallout Meter

    SciTech Connect

    Kearny, C.H.

    2001-11-20

    The KFM is a homemade fallout meter that can be made using only materials, tools, and skills found in millions of American homes. It is an accurate and dependable electroscope-capacitor. The KFM, in conjunction with its attached table and a watch, is designed for use as a rate meter. Its attached table relates observed differences in the separations of its two leaves (before and after exposures at the listed time intervals) to the dose rates during exposures of these time intervals. In this manner dose rates from 30 mR/hr up to 43 R/hr can be determined with an accuracy of {+-}25%. A KFM can be charged with any one of the three expedient electrostatic charging devices described. Due to the use of anhydrite (made by heating gypsum from wallboard) inside a KFM and the expedient ''dry-bucket'' in which it can be charged when the air is very humid, this instrument always can be charged and used to obtain accurate measurements of gamma radiation no matter how high the relative humidity. The heart of this report is the step-by-step illustrated instructions for making and using a KFM. These instructions have been improved after each successive field test. The majority of the untrained test families, adequately motivated by cash bonuses offered for success and guided only by these written instructions, have succeeded in making and using a KFM. NOTE: ''The KFM, A Homemade Yet Accurate and Dependable Fallout Meter'', was published by Oak Ridge National Laboratory report in1979. Some of the materials originally suggested for suspending the leaves of the Kearny Fallout Meter (KFM) are no longer available. Because of changes in the manufacturing process, other materials (e.g., sewing thread, unwaxed dental floss) may not have the insulating capability to work properly. Oak Ridge National Laboratory has not tested any of the suggestions provided in the preface of the report, but they have been used by other groups. When using these instructions, the builder can verify the

  20. An approximation based global optimization strategy for structural synthesis

    NASA Technical Reports Server (NTRS)

    Sepulveda, A. E.; Schmit, L. A.

    1991-01-01

    A global optimization strategy for structural synthesis based on approximation concepts is presented. The methodology involves the solution of a sequence of highly accurate approximate problems using a global optimization algorithm. The global optimization algorithm implemented consists of a branch and bound strategy based on the interval evaluation of the objective function and constraint functions, combined with a local feasible directions algorithm. The approximate design optimization problems are constructed using first order approximations of selected intermediate response quantities in terms of intermediate design variables. Some numerical results for example problems are presented to illustrate the efficacy of the design procedure setforth.