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Sample records for random vitrinite reflectance

  1. Influence of particle and surface quality on the vitrinite reflectance of dispersed organic matter: Comparative exercise using data from the qualifying system for reflectance analysis working group of ICCP

    Science.gov (United States)

    Borrego, A.G.; Araujo, C.V.; Balke, A.; Cardott, B.; Cook, A.C.; David, P.; Flores, D.; Hamor-Vido, M.; Hiltmann, W.; Kalkreuth, W.; Koch, J.; Kommeren, C.J.; Kus, J.; Ligouis, B.; Marques, M.; Mendonca, Filho J.G.; Misz, M.; Oliveira, L.; Pickel, W.; Reimer, K.; Ranasinghe, P.; Suarez-Ruiz, I.; Vieth, A.

    2006-01-01

    The development of a qualifying system for reflectance analysis has been the scope of a working group within the International Committee for Coal and Organic Petrology (ICCP) since 1999, when J. Koch presented a system to qualify vitrinite particles according to their size, proximity to bright components and homogeneity of the surface. After some years of work aimed at improving the classification system using photomicrographs, it was decided to run a round robin exercise on microscopy samples. The classification system tested consists of three qualifiers ranging from excellent to low quality vitrinites with an additional option for unsuitable vitrinites. This paper reports on the results obtained by 22 analysts who were asked to measure random reflectance readings on vitrinite particles assigning to each reading a qualifier. Four samples containing different organic matter types and a variety of vitrinite occurrences have been analysed. Results indicated that the reflectance of particles classified as excellent, good or poor compared to the total average reflectance did not show trends to be systematically lower or higher for the four samples analysed. The differences in reflectance between the qualifiers for any given sample were lower than the scatter of vitrinite reflectance among participants. Overall, satisfactory results were obtained in determining the reflectance of vitrinite in the four samples analysed. This was so for samples having abundant and easy to identify vitrinites (higher plant-derived organic matter) as well as for samples with scarce and difficult to identify particles (samples with dominant marine-derived organic matter). The highest discrepancies were found for the organic-rich oil shales where the selection of the vitrinite population to measure proved to be particularly difficult. Special instructions should be provided for the analysis of this sort of samples. The certainty of identification of the vitrinite associated with the vitrinite

  2. Coal rank (vitrinite reflectance) data for Cretaceous/Tertiary coal measures in the Grande Cache and Hinton areas, Alberta

    Energy Technology Data Exchange (ETDEWEB)

    Kalkreuth, W.D.; Langenberg, W.; McMechan, M.E.; Tomica, M.A.; McDougall, W.; Burchard, K.

    1996-07-01

    A total of 544 vitrinite reflectance values are reported. The outcrop locations and other pertinent data are listed. Vitrinite reflectances determined in subsurface samples from two coal exploration boreholes and 13 petroleum exploration wells are tabulated. The data have been used (in other studies) to evaluate maturation levels in potential source rocks and to assess methane potential of the coal deposits. A diskette containing the data is included. 18 refs., 1 fig., 2 tabs.

  3. The thermal history of the Bowen Basin: a comparison of apatite fission track analysis and vitrinite reflectance

    International Nuclear Information System (INIS)

    Marshallsea, S.J.

    1987-01-01

    Vitrinite reflectance and apatite fission-track analysis (AFTA) are two techiques widely used to assess paleotemperatures of the order of 20-120 deg.C. in sedimentary basins. Whereas vitrinite reflectance is essentially a qualitative technique that gives an integrated measure of the entire thermal history, AFTA can reveal information on the variation of paleotemperatures through time because fission-tracks in apatite are continually produced throughout geological time. An apatite fission track study of the Upper Permian units of the Bowen Basin has offered the opportunity to compare the two paleotemperature indicators and place constraints on the timing of maximum paleotemperatures. The regional pattern of apatite fission-track ages closely coincides with the vitrinite reflectance indicating that maximum paleotemperatures have varied across the Basin with the central region of the Bowen Basin experiencing highest paleotemperatures. The reduction in apatite reflectance fission-track age with increasing reflectance represents the progressive annealing at temperatures around 60-120 deg. C. of those fission-tracks formed prior to the time of maximum temperatures. In those samples giving the youngest apatite fission-track ages all tacks were totally annealed at this time, and the fission-track age in these samples, in the range 90-120 Myr, indicate the time of cooling from the thermal maximum in the Early Cretaceous. 1 ref

  4. Paleothermal structure of the Nankai inner accretionary wedge estimated from vitrinite reflectance of cuttings

    Science.gov (United States)

    Fukuchi, Rina; Yamaguchi, Asuka; Yamamoto, Yuzuru; Ashi, Juichiro

    2017-08-01

    The paleothermal structure and tectonic evolution of an accretionary prism is basic information for understanding subduction zone seismogenesis. To evaluate the entire paleotemperature profile of the Integrated Ocean Drilling Program (IODP) Site C0002 located in the off-Kumano region of the Nankai Trough and penetrate the inner accretionary wedge down to 3058.5 m below the seafloor (mbsf), we performed a vitrinite reflectance analysis for cuttings and core samples during IODP expeditions 338 and 348: Nankai Trough seismogenic zone experiment. Although vitrinite reflectance values (Ro) tend to increase with depth, two reversals of these values suggested the existence of thrust fault zones with sufficient displacements to offset the paleothermal structure. The estimated maximum paleotemperatures are 42-70°C at 1200-1300 mbsf, 44-100°C at 1600-2400 mbsf, and 56-115°C at 2600-3000 mbsf, respectively. These temperatures roughly coincide with estimated modern temperatures; however, at a smaller scale, the reconstructed partial paleogeothermal gradient (˜60-150°C/km) recorded at the hanging- and footwall of the presumed thrust fault zone is higher than the modern geothermal gradient (˜30-40°C/km). This high paleogeothermal gradient was possibly obtained prior to subduction, reflecting the large heat flow of the young Philippine Sea Plate.

  5. Multiple cooling episodes in the Central Tarim (Northwest China) revealed by apatite fission track analysis and vitrinite reflectance data

    Science.gov (United States)

    Chang, Jian; Qiu, Nansheng; Song, Xinying; Li, Huili

    2016-06-01

    Apatite fission track and vitrinite reflectance are integrated for the first time to study the cooling history in the Central Tarim, northwest China. The paleo-temperature profiles from vitrinite reflectance data of the Z1 and Z11 wells showed a linear relationship with depth, suggesting an approximately 24.8 °C/km paleo-geothermal gradient and 2700-3900 m of erosion during the Early Mesozoic. The measured apatite fission track ages from well Z2 in the Central Tarim range from 39 to 159 Ma and effectively record the Meso-Cenozoic cooling events that occurred in Central Tarim. Moreover, two cooling events at 190-140 Ma in the Early Jurassic-Early Cretaceous and 80-45 Ma in the Late Cretaceous-Paleocene revealed by measured AFT data and thermal modeling results are related to the collisions of the Qiangtang-Lhasa terranes and the Greater India Plate with the southern margin of the Eurasian Plate, respectively. This study provides new insights into the tectonic evolution of the Tarim Basin (and more broadly Central Asia) and for hydrocarbon generation and exploration in the Central Tarim.

  6. Structural elucidation, molecular representation and solvent interactions of vitrinite-rich and inertinite-rich South African coals

    Science.gov (United States)

    van Niekerk, Daniel

    the kinetic parameters and it was found that the swelling was governed by relaxation of the coal structure (super-Case II swelling). X-ray computed tomography was conducted confirming anisotropic swelling. The petrographic transitions (maceral-group composition and reflectance) with solvent swelling and extraction were quantified. No changes in the maceral compositions were found, but changes in some coal particles were observed. Random reflectance analysis showed that, for both vitrinite and inertinite, there is a decrease in reflectance values with solvent treatment. Vitrinite reflectograms showed a shift from the dominant reflecting V-types to lower V-types. The inertinite reflectograms exhibited an increase in number of I-types (broadening of reflectrograms). Molecular simulation and visualization approaches to solvent swelling and extraction were performed on the proposed molecular models of vitrinite-rich and inertinite-rich coals. A theoretical extraction yield was determined using solubility parameters and showed agreement with experimental extraction yield trends. Statistical Associating Fluid Theory (SAFT) modeling was explored to test whether this method could predict swelling extent. The predicted swelling trends of SAFT were comparable to that of the experimental swelling results. SAFT was found to be a promising tool for solvent-coal interaction predictions. Partially solvent swollen structures were constructed by the addition of solvent molecules to the original coal molecules using a amorphous building approach. This method showed that coal-coal non-bonding interaction changed with the introduction of solvent. A disruption in the van der Waals interaction energies and a change in hydrogen bond distributions were observed in the swollen coal models and quantified. It was concluded that small changes in coal structure translates to significant changes in solvent interaction behavior. These changes were successfully visualized and simulated using

  7. Macromolecule simulation and CH{sub 4} adsorption mechanism of coal vitrinite

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Song, E-mail: songyu10094488@126.com [School of Resources and Earth Science, China University of Mining & Technology, Xuzhou 221116 (China); Key Laboratory of Coal bed Methane Resource & Reservoir Formation Process, Ministry of Education, Xuzhou 221008 (China); Yan-ming, Zhu; Wu, Li [School of Resources and Earth Science, China University of Mining & Technology, Xuzhou 221116 (China); Key Laboratory of Coal bed Methane Resource & Reservoir Formation Process, Ministry of Education, Xuzhou 221008 (China)

    2017-02-28

    Highlights: • Molecular model of single maceral vitrinite was obtained by {sup 13}C NMR, FT IR and HRTEM. • An optimal configuration was obtained through calculation of MM and MD. • The adsorption parameters for methane and vitrinite were determined with DFT and GCMC. - Abstract: The microscopic mechanism of interactions between CH{sub 4} and coal macromolecules is of significant practical and theoretical importance in CBM development and methane storage. Under periodic boundary conditions, the optimal energy configuration of coal vitrinite, which has a higher torsion degree and tighter arrangement, can be determined by the calculation of molecular mechanics (MM) and molecular dynamics (MD), and annealing kinetics simulation based on ultimate analysis, {sup 13}C NMR, FT IR and HRTEM. Macromolecular stabilization is primarily due to the van der Waals energy and covalent bond energy, mainly consisting of bond torsion energy and bond angle energy. Using the optimal configuration as the adsorbent, GCMC simulation of vitrinite adsorption of CH{sub 4} is conducted. A saturated state is reached after absorbing 17 CH{sub 4}s per coal vitrinite molecule. CH{sub 4} is preferentially adsorbed on the edge, and inclined to gathering around the branched chains of the inner vitrinite sites. Finally, the adsorption parameters are calculated through first principle DFT. The adsorbability order is as follows: aromatic structure> heteroatom rings > oxygen functional groups. The adsorption energy order is as follows: Top < Bond < Center, Up < Down. The order of average RDF better reflects the adsorption ability and that of [-COOH] is lower than those of [−C=O] and [C−O−C]. CH{sub 4} distributed in the distance of 0.99–16 Å to functional groups in the type of monolayer adsorption and the average distance order manifest as [−C=O] (1.64 Å) < [C−O−C] (1.89 Å) < [−COOH] (3.78 Å) < [-CH{sub 3}] (4.11 Å) according to the average RDF curves. CH{sub 4} enriches

  8. Evolution of the Cerro Prieto geothermal system as interpreted from vitrinite reflectance under isothermal conditions

    Energy Technology Data Exchange (ETDEWEB)

    Barker, C.E. (US Geological Survey, Denver, CO); Pawlewicz, M.J.; Bostick, N.H.; Elders, W.A.

    1981-01-01

    Temperature estimates from reflectance data in the Cerro Prieto system correlate with modern temperature logs and temperature estimates from fluid inclusion and oxygen isotope geothermometry indicating that the temperature in the central portion of the Cerro Prieto System is now at its historical maximum. Isoreflectance lines formed by contouring vitrinite reflectance data for a given isothermal surface define an imaginary surface that indicates an apparent duration of heating in the system. The 250/sup 0/C isothermal surface has a complex dome-like form suggesting a localized heat source that has caused shallow heating in the central portion of this system. Isoreflectance lines relative to this 250/sup 0/C isothermal surface define a zone of low reflectance roughly corresponding to the crest of the isothermal surface. Comparison of these two surfaces suggest that the shallow heating in the central portion of Cerro Prieto is young relative to the heating (to 250/sup 0/C) on the system margins. Laboratory and theoretical models of hydrothermal convection cells suggest that the form of the observed 250/sup 0/C isothermal surface and the reflectance surface derived relative to it results from the convective rise of thermal fluids under the influence of a regional hydrodynamic gradient that induces a shift of the hydrothermal heating effects to the southwest.

  9. Variations in vitrinite reflectance with organic facies - examples from Pennsylvanian cyclothems of the Midcontinent, USA

    Energy Technology Data Exchange (ETDEWEB)

    Wenger, L M; Baker, D R

    1987-01-01

    Significant variations in vitrinite reflectance (% R/sub o/) with organic facies have been demonstrated from Pennsylvanian -aged cyclothems of the Midcontinent, USA. Thermal alteration index (TAI) and Rock-Eval T/sub m/ax values remain relatively constant through these thin lithologic successions, regardless of facies, and are in reasonable agreement with R/sub o/ measurements on interbedded coal. Organic-rich black and phosphatic black-shales, which contain significant component of liptinitic organic matter of presumed marine algal derivation, display R/sub o/ values which are suppressed relative to the coal benchmark. A distinct correlation between increased hydrogen index (HI) and liptinite content with suppressed reflectivities is apparent. More oxic facies (e.g. calcareous and fossiliferous gray shales and limestones) often display R/sub o/'s that are considerably higher than for coal. Soxhlet extraction prior to maceration yielded no variation in reflectance compared to non-extracted kerogens suggesting bitumen adsorption was not the cause of the apparent suppression in the organic-rich black-shales. Lower total organic carbon (TOC)-normalized bitumen contents and Rock-Eval transformations ratios in liptinite-rich facies suggest differential reaction kinetics for kerogen types, with terrestrial organic matter 'maturing' at an earlier stage than hydrogen-rich marine-derived organic matter. 8 refs., 6 figs., 1 tab.

  10. Simulations and experimental investigations of the competitive adsorption of CH4 and CO2 on low-rank coal vitrinite.

    Science.gov (United States)

    Yu, Song; Bo, Jiang; Jiahong, Li

    2017-09-16

    The mechanism for the competitive adsorption of CH 4 and CO 2 on coal vitrinite (DV-8, maximum vitrinite reflectance R o,max  = 0.58%) was revealed through simulation and experimental methods. A saturated state was reached after absorbing 17 CH 4 or 22 CO 2 molecules per DV-8 molecule. The functional groups (FGs) on the surface of the vitrinite can be ranked in order of decreasing CH 4 and CO 2 adsorption ability as follows: [-CH 3 ] > [-C=O] > [-C-O-C-] > [-COOH] and [-C-O-C-] > [-C=O] > [-CH 3 ] > [-COOH]. CH 4 and CO 2 distributed as aggregations and they were both adsorbed at the same sites on vitrinite, indicating that CO 2 can replace CH 4 by occupying the main adsorption sites for CH 4 -vitrinite. High temperatures are not conducive to the adsorption of CH 4 and CO 2 on vitrinite. According to the results of density functional theory (DFT) and grand canonical Monte Carlo (GCMC) calculations, vitrinite has a higher adsorption capacity for CO 2 than for CH 4 , regardless of whether a single-component or binary adsorbate is considered. The equivalent adsorption heat (EAH) of CO 2 -vitrinite (23.02-23.17) is higher than that of CH 4 -vitrinite (9.04-9.40 kJ/mol). The EAH of CO 2 -vitrinite decreases more rapidly with increasing temperature than the EAH of CH 4 -vitrinite does, indicating in turn that the CO 2 -vitrinite bond weakens more quickly with increasing temperature than the CH 4 -vitrinite bond does. Simulation data were found to be in good accord with the corresponding experimental results.

  11. Macromolecule simulation and CH4 adsorption mechanism of coal vitrinite

    Science.gov (United States)

    Yu, Song; Yan-ming, Zhu; Wu, Li

    2017-02-01

    The microscopic mechanism of interactions between CH4 and coal macromolecules is of significant practical and theoretical importance in CBM development and methane storage. Under periodic boundary conditions, the optimal energy configuration of coal vitrinite, which has a higher torsion degree and tighter arrangement, can be determined by the calculation of molecular mechanics (MM) and molecular dynamics (MD), and annealing kinetics simulation based on ultimate analysis, 13C NMR, FT IR and HRTEM. Macromolecular stabilization is primarily due to the van der Waals energy and covalent bond energy, mainly consisting of bond torsion energy and bond angle energy. Using the optimal configuration as the adsorbent, GCMC simulation of vitrinite adsorption of CH4 is conducted. A saturated state is reached after absorbing 17 CH4s per coal vitrinite molecule. CH4 is preferentially adsorbed on the edge, and inclined to gathering around the branched chains of the inner vitrinite sites. Finally, the adsorption parameters are calculated through first principle DFT. The adsorbability order is as follows: aromatic structure> heteroatom rings > oxygen functional groups. The adsorption energy order is as follows: Top graphene. However, the energy of the most preferential location is much lower than that of graphite/graphene. CH4 is more easily absorbed on the surface of vitrinite. Adsorbability varies considerably at different adsorption locations and sites on the surface of vitrinite. Crystal parameter of vitrinite is a = b = c = 15.8 Å and majority of its micropores are blow 15.8 Å, indicating that the vitrinite have the optimum adsorption aperture. It can explain its higher observed adsorption capacities for CH4 compared with graphite/graphene.

  12. The new vitrinite classification (ICCP System 1994)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-04-01

    This paper has been prepared by the International Committee for Coal and Organic Petrology (ICCP). Within the new vitrinite classification (ICCP System 1994) the maceral group vitrinite is divided into three subgroups, telovitrinite, detrovitrinite and gelovitrinite, which are each further sub-divided into two macerals. The dominant parameter for these newly ordered and in part newly defined sub-groups is the degree of destruction (degradation), whereas the macerals can be further distinguished by their morphological characteristics and their degree of gelificiation. The new system is furthermore related more closely to the huminite classification system still in use and a future one to be published by the ICCP. 69 refs., 2 figs., 2 tabs.

  13. The thermal history of the Karoo Moatize-Minjova Basin, Tete Province, Mozambique: An integrated vitrinite reflectance and apatite fission track thermochronology study

    Science.gov (United States)

    Fernandes, Paulo; Cogné, Nathan; Chew, David M.; Rodrigues, Bruno; Jorge, Raul C. G. S.; Marques, João; Jamal, Daud; Vasconcelos, Lopo

    2015-12-01

    The Moatize-Minjova Basin is a Karoo-aged rift basin located in the Tete Province of central Mozambique along the present-day Zambezi River valley. In this basin the Permian Moatize and Matinde formations consist of interbedded carbonaceous mudstones and sandstones with coal seams. The thermal history has been determined using rock samples from two coal exploration boreholes (ca. 500 m depth) to constrain the burial and exhumation history of the basin. Organic maturation levels were determined using vitrinite reflectance and spore fluorescence/colour. Ages and rates of tectonic uplift and denudation have been assessed by apatite fission track analysis. The thermal history was modelled by inverse modelling of the fission track and vitrinite reflectance data. The Moatize Formation attained a coal rank of bituminous coals with low to medium volatiles (1.3-1.7%Rr). Organic maturation levels increase in a linear fashion downhole in the two boreholes, indicating that burial was the main process controlling peak temperature maturation. Calculated palaeogeothermal gradients range from 59 °C/km to 40 °C/km. According to the models, peak burial temperatures were attained shortly (3-10 Ma) after deposition. Apatite fission track ages [146 to 84 Ma (Cretaceous)] are younger than the stratigraphic age. Thermal modelling indicates two episodes of cooling and exhumation: a first period of rapid cooling between 240 and 230 Ma (Middle - Upper Triassic boundary) implying 2500-3000 m of denudation; and a second period, also of rapid cooling, from 6 Ma (late Miocene) onwards implying 1000-1500 m of denudation. The first episode is related to the main compressional deformation event within the Cape Fold Belt in South Africa, which transferred stress northwards on pre-existing transtensional fault systems within the Karoo rift basins, causing tectonic inversion and uplift. During the Mesozoic and most of the Cenozoic the basin is characterized by very slow cooling. The second period

  14. Measurement of reflectance of coal macerals: its automation and significance

    Energy Technology Data Exchange (ETDEWEB)

    Davis, A.

    1978-06-01

    A prime objective of the Pennsylvania State University's DOE program is the characterization of 1,300 samples of U.S. coals. Reflectance determination plays a major role in meeting this objective, because it is used as an accurate rank index both to select coals for testing and to investigate property-behavior interrelationships using the Penn State/DOE Coal Data Base. Reflectances of coal macerals are related to their refractive and absorptive indices by the Beer equation; the refractive index of the medium and the wavelength of light need to be specified. Determinations usually are made in immersion oil at 546 nm. Properties of vitrinite make it the most suitable maceral for these measurements, but the variety of vitrinite selected may depend upon the intended application. Vitrinite reflectance is considered to be dependent upon the degree of aromatization of its structural units. Although some of the earlier investigators believed that the reflectance of coals increased in a discontinuous, stepped manner as their rank increased, the bulk of assembled data suggests that the change is continuous. Some recent results indicate that there may be more than one coalification track for coals with different geological histories, resulting in displacement from the general trend. Several techniques have been employed to determine the optical properties of coal constituents. Usual comparative method involves the use of a microscope photometer to compare the intensity of light reflected by particles within a polished pellet of coal to that of a glass or synthetic mineral standard. Because coal is anisotropic it is common to measure either maximum reflectance in polarized light or random reflectance in non-polarized light. Various eqipment modifications and accessories have been used to improve the ease of measuring maximum reflectance.

  15. Standardization of reflectance measurements in dispersed organic matter: results of an exercise to improve interlaboratory agreement

    Science.gov (United States)

    Hackley, Paul C.; Araujo, Carla Viviane; Borrego, Angeles G.; Bouzinos, Antonis; Cardott, Brian; Cook, Alan C.; Eble, Cortland; Flores, Deolinda; Gentzis, Thomas; Gonçalves, Paula Alexandra; Filho, João Graciano Mendonça; Hámor-Vidó, Mária; Jelonek, Iwona; Kommeren, Kees; Knowles, Wayne; Kus, Jolanta; Mastalerz, Maria; Menezes, Taíssa Rêgo; Newman, Jane; Pawlewicz, Mark; Pickel, Walter; Potter, Judith; Ranasinghe, Paddy; Read, Harold; Reyes, Julito; Rodriguez, Genaro De La Rosa; de Souza, Igor Viegas Alves Fernandes; Suarez-Ruiz, Isabel; Sýkorová, Ivana; Valentine, Brett J.

    2015-01-01

    Vitrinite reflectance generally is considered the most robust thermal maturity parameter available for application to hydrocarbon exploration and petroleum system evaluation. However, until 2011 there was no standardized methodology available to provide guidelines for vitrinite reflectance measurements in shale. Efforts to correct this deficiency resulted in publication of ASTM D7708: Standard test method for microscopical determination of the reflectance of vitrinite dispersed in sedimentary rocks. In 2012-2013, an interlaboratory exercise was conducted to establish precision limits for the D7708 measurement technique. Six samples, representing a wide variety of shale, were tested in duplicate by 28 analysts in 22 laboratories from 14 countries. Samples ranged from immature to overmature (0.31-1.53% Ro), from organic-lean to organic-rich (1-22 wt.% total organic carbon), and contained Type I (lacustrine), Type II (marine), and Type III (terrestrial) kerogens. Repeatability limits (maximum difference between valid repetitive results from same operator, same conditions) ranged from 0.03-0.11% absolute reflectance, whereas reproducibility limits (maximum difference between valid results obtained on same test material by different operators, different laboratories) ranged from 0.12-0.54% absolute reflectance. Repeatability and reproducibility limits degraded consistently with increasing maturity and decreasing organic content. However, samples with terrestrial kerogens (Type III) fell off this trend, showing improved levels of reproducibility due to higher vitrinite content and improved ease of identification. Operators did not consistently meet the reporting requirements of the test method, indicating that a common reporting template is required to improve data quality. The most difficult problem encountered was the petrographic distinction of solid bitumens and low-reflecting inert macerals from vitrinite when vitrinite occurred with reflectance ranges overlapping

  16. Detection of frictional heat in seismic faults by coal reflectance

    Science.gov (United States)

    Kitamura, M.; Mukoyoshi, H.; Fulton, P. M.; Hirose, T.

    2012-12-01

    Quantitative assessment of heat generation along a fault during coseismic faulting is of primary importance in understanding the dynamics of earthquakes. Evidence of substantial frictional heating along a fault is also a reliable indicator determining whether a fault has slipped at high velocity in the past, which is crucial for assessing earthquake and tsunami hazard. The reflectance measurement of vitrinite (one of the primary components of coals) has been considered a possible geothermometer of fault zones, especially in accretionary wedges where vitrinite fragments are common [e.g., Sakaguchi et al., 2011]. Under normal burial conditions, vitrinite reflectance (Ro) increases by irreversible maturation reaction as temperature is elevated and thus sensitively records the maximum temperature to which the vitrinite is subjected. However, the commonly used kinetic models of vitrinite maturation [e.g., Sweeney and Burnham, 1990] may not yield accurate estimates of the peak temperature in a fault zone resulting from fast frictional heating rates [Fulton and Harris, 2012]. Whether or not coal can mature in typical earthquake rise time (e.g., ~10 seconds) remains uncertain. Here we present the results of friction experiments aimed at revealing coal maturation by frictional heat generated at slip velocities representative of natural earthquakes of up to 1.3 m/s. All friction experiments were conducted on a mixture of 90 wt% quartz powder and 10 wt% coal grains for simulated fault gouge at three different velocities of 0.0013 m/s, 0.65 m/s and 1.3 m/s, a constant normal stress of 1.0 MPa and ~15 m displacement under anoxic, dry nitrogen atmosphere at room temperature. We also measured temperature in the gouge zone during faulting by thermocouples. The initial coal fragments consist of vitrinite, inertinite and liptinite. Although liptinite was easy to identify microscopically, it was difficult to discriminate between vitrinite and inertinite grains as their grain size

  17. Application of integrated vitrinite reflectance and FAMM analyses for thermal maturity assessment of the northeastern Malay Basin, offshore Vietnam: Implications for petroleum prospectivity evaluation

    DEFF Research Database (Denmark)

    Petersen, H. I.; Sherwood, N.; Mathiesen, A.

    2008-01-01

    Several exploration wells have intersected a Cenozoic coal-bearing, fluvial-deltaic mudstone and sandstone succession in the northeastern Vietnamese part of the Malay Basin, and have successfully tested seismically identified direct hydrocarbon indicators (DHIs). The oil and gas/condensate discov......Several exploration wells have intersected a Cenozoic coal-bearing, fluvial-deltaic mudstone and sandstone succession in the northeastern Vietnamese part of the Malay Basin, and have successfully tested seismically identified direct hydrocarbon indicators (DHIs). The oil and gas...... for the uppermost Oligocene source rocks between 2Ma and present-day, which post-dates trap formation. Seismic facies patterns suggest that lacustrine oil-prone units are in he oil window in the same graben complex a few km NW of the investigated well, and these rocks are likely to be the source of the hydrocarbons....../condensate discovery ell 46-CN-1x encountered a _55m thick section of lacustrine mudstones having considerable potential as an oil source. Vitrinite reflectance (VR) measurements from these alginite-bearing rocks introduce several problems in thermal maturity evaluation, including associated VR suppression...

  18. Preliminary vitrinite and bitumen reflectance, total organic carbon, and pyrolysis data for samples from Upper and Lower Cretaceous strata, Maverick Basin, south Texas

    Science.gov (United States)

    Hackley, Paul C.; Dennen, Kristin O.; Gesserman, Rachel M.; Ridgley, Jennie L.

    2009-01-01

    The Lower Cretaceous Pearsall Formation, a regionally occurring limestone and shale interval of 500-600-ft maximum thickness (Rose, 1986), is being evaluated as part of an ongoing U.S. Geological Survey (USGS) assessment of undiscovered hydrocarbon resources in onshore Lower Cretaceous strata of the northern Gulf of Mexico. The purpose of this report is to release preliminary vitrinite and bitumen reflectance, total organic carbon, and pyrolysis data for Pearsall Formation, Glen Rose Formation, Hosston Formation, Austin Group, and Eagle Ford Group samples from the Maverick Basin in south Texas in order to aid in the characterization of these strata in this area. The preliminary nature of this report and the data contained herein reflect that the assessment and characterization of these samples is a work currently in progress. Pearsall Formation subdivisions are, in ascending stratigraphic order, the Pine Island Shale, James Limestone, and Bexar Shale Members (Loucks, 2002). The Lower Cretaceous Glen Rose Formation is also part of the USGS Lower Cretaceous assessment and produces oil in the Maverick Basin (Loucks and Kerans, 2003). The Hosston Formation was assessed by the USGS for undiscovered oil and gas resources in 2006 (Dyman and Condon, 2006), but not in south Texas. The Upper Cretaceous Austin Group is being assessed as part of the USGS assessment of undiscovered hydrocarbon resources in the Upper Cretaceous strata of the northern Gulf of Mexico and, along with the Upper Cretaceous Eagle Ford Group, is considered to be an important source rock in the Smackover-Austin-Eagleford Total Petroleum System (Condon and Dyman, 2006). Both the Austin Group and the Eagle Ford Group are present in the Maverick Basin in south Texas (Rose, 1986).

  19. EPR evidence for thermally excited triplet states in exinite, vitrinite and inertinite separated from bituminous coal

    Energy Technology Data Exchange (ETDEWEB)

    Slowik, G.P.; Wojtowicz, W.; Wieckowski, A.B. [University of Zielona Gora, Zielona Gora (Poland). Inst. of Physics

    2005-07-01

    In this work we have made an electron spin resonance (EPR) study of macerals obtained from the lithotype clarain separated from Polish medium-rank coal (85.6 wt.% C). For three macerals (exinite, vitrinite, and inertinite), the temperature dependence of intensity of EPR spectra in the temperature range of 100-373 K was investigated. The experimentally obtained EPR spectra of macerals were fitted by curves of the derivatives of the Gaussian and Lorentzian functions. The best fitting was obtained, when the experimental EPR spectra were assumed to be a superposition of three lines, for exinite and vitrinite - a broad Gaussian (G), a broad Lorentzian (L1) and a narrow Lorentzian (L3) line, but for inertinite of two lines - a narrow Lorentzian (L2) and a narrow Lorentzian (L3) line. The computer-assisted fitting has shown that each individual component line has similar values of resonance field, but different linewidths and amplitudes. The temperature dependence of line intensity I of the broad Gaussian (G) and narrow Lorentzian (L2 and L3) lines fulfils the Curie law in the form I = C/T or IT = C, whereas the broad Lorentzian (L1) line does not fulfil the Curie law. In the last case the temperature dependence of the Lorentzian (L1) component was fitted by the relation I = C/T + B/(T(3 + exp(J/kT))) or IT C + B/(3 + exp(J/kT))), valid for thermally excited triplet states (S = 1). For exinite and vitrinite the curves presenting the temperature dependence of the product IT versus temperature T were resolved into two curves, one for paramagnetic centres in the doublet state (S = ), and the other for paramagnetic centres in the thermally excited triplet state (S = 1).

  20. Standardization of reflectance measurements in dispersed organic matter: Results of an exercise to improve interlaboratory agreement

    Czech Academy of Sciences Publication Activity Database

    Hackley, P.C.; Araujo, C.V.; Borrego, A.G.; Bouzinos, A.; Cardott, B.J.; Cook, A.C.; Eble, C.; Flores, D.; Gentzis, T.; Goncalves, P.A.; Mendonca Filho, J.G.; Hámor-Vidó, M.; Jelonek, I.; Kommeren, K.; Knowles, W.; Kus, J.; Mastalerz, M.; Menezes, T.R.; Newman, J.; Oikonomopoulos, I.K.; Pawlewicz, M.; Pickel, W.; Potter, J.; Ranasinghe, P.; Read, H.; Reyes, J.; De La Rosa Rodriguez, G.; de Souza, I.V.A.F.; Suárez-Ruiz, I.; Sýkorová, Ivana; Valentine, B.J.

    2015-01-01

    Roč. 59, JAN (2015), s. 22-34 ISSN 0264-8172 Institutional support: RVO:67985891 Keywords : vitrinite reflectance * thermal maturity * shale petroleum systems * microscopy * hydrocarbon exploration Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.788, year: 2015 http://www.sciencedirect.com/science/article/pii/S0264817214002402

  1. Thermal maturity of northern Appalachian Basin Devonian shales: Insights from sterane and terpane biomarkers

    Science.gov (United States)

    Hackley, Paul C.; Ryder, Robert T.; Trippi, Michael H.; Alimi, Hossein

    2013-01-01

    To better estimate thermal maturity of Devonian shales in the northern Appalachian Basin, eleven samples of Marcellus and Huron Shale were characterized via multiple analytical techniques. Vitrinite reflectance, Rock–Eval pyrolysis, gas chromatography (GC) of whole rock extracts, and GC–mass spectrometry (GCMS) of extract saturate fractions were evaluated on three transects that lie across previously documented regional thermal maturity isolines. Results from vitrinite reflectance suggest that most samples are immature with respect to hydrocarbon generation. However, bulk geochemical data and sterane and terpane biomarker ratios from GCMS suggest that almost all samples are in the oil window. This observation is consistent with the presence of thermogenic gas in the study area and higher vitrinite reflectance values recorded from overlying Pennsylvanian coals. These results suggest that vitrinite reflectance is a poor predictor of thermal maturity in early mature areas of Devonian shale, perhaps because reported measurements often include determinations of solid bitumen reflectance. Vitrinite reflectance interpretations in areas of early mature Devonian shale should be supplanted by evaluation of thermal maturity information from biomarker ratios and bulk geochemical data.

  2. The kinetics of sterane biological marker release and degradation processes during the hydrous pyrolysis of vitrinite kerogen

    Science.gov (United States)

    Abbott, G. D.; Wang, G. Y.; Eglinton, T. I.; Home, A. K.; Petch, G. S.

    1990-09-01

    The hydrous pyrolysis of a mineral-free vitrinite kerogen (Dinantian coal Lower Carboniferous, North East England) has been carried out at four temperatures (270, 300, 330, and 350°C) for heating times ranging from 2 to 648 h. No significant differences in the epimer-based maturation parameters 20S/(20S + 20R)-5α(H),14α(H),17α(H) C 29 non-rearranged steranes and 22S/(22S+22R)-17α(H), 21β(H) homohopanes were found for a comparison between "expelled oil" and "bitumen" fractions in the resulting pyrolysates. A deuterated model compound ((20R)-5α(H),14α(H),17α(H)-[2,2,4,4-d 4] cholestane) was added to a number of preextracted kerogens (vitrinite, Kimmeridge, Messel and Monterey) and the mixtures were heated under typical hydrous pyrolysis conditions. These experiments showed that direct chiral isomerisation at C-20 in the non-rearranged steranes appears to be relatively unimportant during hydrous pyrolysis which has also been suggested by other recent studies on geological samples.A kinetic model comprising consecutive release and degradation processes was derived to measure first-order rate coefficients from the bi-exponential concentration-time functions of both the (20R)-and (20S)-5α(H),14α(H),17α(H) C 29 "free" steranes in the vitrinite kerogen pyrolysates. This data was then used to calculate preliminary Arrhenius parameters for release ((20S): ΔEa = 125 ± 30 kJ mol -1, A ≈ 4.7 × 10 5 s -1;(20R): ΔEa = 151 ± 39 kJ mol -1, A ≈ 2.7 × 10 9 s -1) and degradation ((20S): ΔEa = 104 ± 22 kJ mol -1, A ≈ 5.8 × 10 3 s -1; (20R): Δa = 87 ± 6 kJ mol -1, A ≈ 2.2 × 10 2 s -1) of the above individual isomers and the values were found to be consistent with a free-radical chain mechanism. This work helps in the greater understanding of the important biomarker reactions that prevail in hydrous pyrolysis experiments.

  3. Effect of concentration of dispersed organic matter on optical maturity parameters. Interlaboratory results of the organic matter concentration working group of the ICCP

    Energy Technology Data Exchange (ETDEWEB)

    Mendonca Filho, J.G.; Kern, M.L.; Mendonca, J.O. [Palynofacies and Organic Facies Laboratory (LAFO), DEGL, IGEO, UFRJ, Cidade Universitaria, Rio de Janeiro (Brazil); Araujo, C.V.; Menezes, T.R.; Souza, I.V.A.F. [Petrobras R and D Center, Rio de Janeiro (Brazil); Borrego, A.G.; Suarez-Ruiz, I. [Instituto Nacional del Carbon, CSIC, Oviedo (Spain); Cook, A.; Ranasinghe, P. [Keiraville Konsultants Pty. Ltd, NSW (Australia); Flores, D. [University of Porto, Departamento de Geologia (Portugal); Hackley, P. [U.S. Geological Survey, MS 956 National Center Reston, VA (United States); Hower, J.C. [University of Kentucky, Center for Applied Energy Research, Lexington (United States); Kommeren, K. [Shell International Exploration and Production, Rijswijk (Netherlands); Kus, J. [Germany Federal Institute for Geosciences and Natural Resources in Geozentrum, Hannover (Germany); Mastalerz, M. [Indiana Geological Survey, Indiana University, Bloomington (United States); Newman, J. [Newman Energy Research Ltd, Christchurch (New Zealand); Ujiie, Y. [Graduate School of Science and Technology, Hirosaki University (Japan)

    2010-12-01

    The main objective of this work was to study the effect of the kerogen isolation procedures on maturity parameters of organic matter using optical microscopes. This work represents the results of the Organic Matter Concentration Working Group (OMCWG) of the International Committee for Coal and Organic Petrology (ICCP) during the years 2008 and 2009. Four samples have been analysed covering a range of maturity (low and moderate) and terrestrial and marine geological settings. The analyses comprise random vitrinite reflectance measured on both kerogen concentrate and whole rock mounts and fluorescence spectra taken on alginite. Eighteen participants from twelve laboratories from all over the world performed the analyses. Samples of continental settings contained enough vitrinite for participants to record around 50 measurements whereas fewer readings were taken on samples from marine setting. The scatter of results was also larger in the samples of marine origin. Similar vitrinite reflectance values were in general recorded in the whole rock and in the kerogen concentrate. The small deviations of the trend cannot be attributed to the acid treatment involved in kerogen isolation but to reasons related to components identification or to the difficulty to achieve a good polish of samples with high mineral matter content. In samples difficult to polish, vitrinite reflectance was measured on whole rock tended to be lower. The presence or absence of rock fabric affected the selection of the vitrinite population for measurement and this also had an influence in the average value reported and in the scatter of the results. Slightly lower standard deviations were reported for the analyses run on kerogen concentrates. Considering the spectral fluorescence results, it was observed that the {lambda}max presents a shift to higher wavelengths in the kerogen concentrate sample in comparison to the whole-rock sample, thus revealing an influence of preparation methods (acid treatment

  4. Return probabilities for the reflected random walk on N_0

    NARCIS (Netherlands)

    Essifi, R.; Peigné, M.

    2015-01-01

    Let \\((Y_n)\\) be a sequence of i.i.d. \\(\\mathbb{Z }\\)-valued random variables with law \\(\\mu \\). The reflected random walk \\((X_n)\\) is defined recursively by \\(X_0=x \\in \\mathbb{N }_0, X_{n+1}=\\vert X_n+Y_{n+1}\\vert \\). Under mild hypotheses on the law \\(\\mu \\), it is proved that, for any \\( y \\in

  5. Transmission and Andreev reflection in one-dimensional chain with randomly doped superconducting grains

    International Nuclear Information System (INIS)

    Hu Dongsheng; Xiong Shijie

    2002-01-01

    We investigate the transport properties and Andreev reflection in one-dimensional (1D) systems with randomly doped superconducting grains. The superconducting grains are described by the Bogoliubov-de Gene Hamiltonian and the conductance is calculated by using the transfer matrix method and Landauer-Buettiker formula. It is found that although the quasiparticle states are localized due to the randomness and the low dimensionality, the conductance is still kept finite in the thermodynamical limit due to the Andreev reflection. We also investigate the effect of correlation of disorder in such systems and the results show the delocalization of quasiparticle states and suppression of Andreev reflection in a wide energy window

  6. Application of reflectance micro-Fourier Transform infrared analysis to the study of coal macerals: An example from the Late Jurassic to Early Cretaceous coals of the Mist Mountain Formation, British Columbia, Canada

    Science.gov (United States)

    Mastalerz, Maria; Bustin, R.M.

    1996-01-01

    The applicability of the reflectance micro-Fourier Transform infra-red spectroscopy (FTIR) technique for analyzing the distribution of functional groups in coal macerals is discussed. High quality of spectra, comparable to those obtained using other FTIR techniques (KBr pellet and transmission micro-FTIR), indicate this technique can be applied to characterizing functional groups under most conditions. The ease of sample preparation, the potential to analyze large intact samples, and ability to characterize organic matter in areas as small as 20 ??m are the main advantages of reflectance micro-FTIR. The quantitative aspects of reflectance micro-FTIR require further study. The examples from the coal seams of the Mist Mountain Formation, British Columbia show that at high volatile bituminous rank, reflectance micro-FTIR provides valuable information on the character of aliphatic chains of vitrinite and liptinite macerals. Because the character of aliphatic chains influences bond disassociation energies, such information is useful from a hydrocarbon generation viewpoint. In medium volatile bituminous coal liptinite macerals are usually not detectable but this technique can be used to study the degree of oxidation and reactivity of vitrinite and semifusinite.

  7. The role of random nanostructures for the omnidirectional anti-reflection properties of the glasswing butterfly

    Science.gov (United States)

    Siddique, Radwanul Hasan; Gomard, Guillaume; Hölscher, Hendrik

    2015-04-01

    The glasswing butterfly (Greta oto) has, as its name suggests, transparent wings with remarkable low haze and reflectance over the whole visible spectral range even for large view angles of 80°. This omnidirectional anti-reflection behaviour is caused by small nanopillars covering the transparent regions of its wings. In difference to other anti-reflection coatings found in nature, these pillars are irregularly arranged and feature a random height and width distribution. Here we simulate the optical properties with the effective medium theory and transfer matrix method and show that the random height distribution of pillars significantly reduces the reflection not only for normal incidence but also for high view angles.

  8. Oxidation and carbonisation of coals: a case study of coal fire affected coals from the Wuda coalfield, Inner Mongolia, China

    Science.gov (United States)

    Kus, Jolanta; Meyer, Uwe; Ma, Jianwei; Chen-Brauchler, Dai

    2010-05-01

    At the coalfield of Wuda (Inner Mongolia, PR China) extensive underground coal fires cause widespread thermal and oxidative effects in coal seams. Within phase B of the Coal Fire Research Project of the Sino-German Initiative, methods for innovative fire-extinguishing technologies were investigated in multifaceted research approaches. Extensive investigations of oxidative and thermally affected coal seams in coal fire zone 18 were conducted in 2008 prior to application of new fire-extinguishing methods. We present results from the outcrop of coal seam No. 4 in the fire zone 18. The coal of seam No. 4 is of Early Permian age and belongs stratigraphically to the Shanxi Formation. The unaffected coal displays a high volatile bituminous A rank with a background value of random vitrinite reflectance ranging from 0.90 to 0.96 % Rr. Coal channel samples were coallected at actively extracted coal faces along multiple profiles with surface temperatures ranging from about 50° to 600°C. Microscopic examinations revealed a variety of products of coal exposure to the fire. Within coal samples, a marked rise in vitrinite reflectance from background values to 5.55% Rr (6.00 % Rmax) is encountered. In addition, a number of coal samples showed suppressed vitrinite reflectances ranging between 0.82 to 0.88% Rr. Further, seemingly heat unaffected coal samples display intensive development of oxidations rims at coal grain edges and cracks as well as shrinkage cracks and formation of iron oxides/hydroxides. Instead, thermally affected coal samples with higher coalification grade are further characterised by development of macropores (devolatilisation pores) in vitrinitic streaks, transformation of liptinite to meta-liptinite and micrinite as well as by natural coke particles of mostly porous nature and fine to coarse grained anisotropic mosaic. Coal petrographic investigations confirmed a hypothesis that both, oxidations as well as low temperature carbonisation govern the thermal

  9. Prediction of coal reactivity during combustion and gasification by using petrographic data

    Energy Technology Data Exchange (ETDEWEB)

    Furimsky, E.; Palmer, A.D.; Kalkreuth, W.D.; Cameron, A.R.; Kovacik, G.

    1990-06-01

    Petrographic data were correlated with calorific value, oxygen content, fuel ratio, ignition temperature, oxygen chemisorption and selected gasification reactivity data of twenty one Canadian coals (17 from Western and 4 from Eastern Canada). Both parameters are suitable for predicting other coal properties in the absence of mineral matter effects. Using ignition temperature and oxygen chemisorption the series of coals can be divided into three groups. The first group, characterized by low ignition temperatures and low oxygen chemisorption, had mean vitrinite reflectance and/or petrofactor less than 0.6 and/or 7.0 The second group, characterized by the largest oxygen chemisorption and intermediate ignition temperatures had mean vitrinite reflectance and/or petrofactor in the range of 0.6 to 1.0 and/or 7.0 to 11.0. The third group, characterized by the highest ignition temperatures and the lowest oxygen chemisorption had mean vitrinite reflectance and/or petrofactor greater than about 1.0 and/or 11.0. Calorific value and ignition temperature are good correlating parameters for low rank coals, whereas fuel ratio is suitable for higher rank coals. The petrofactor as a correlating parameter offered little advantage compared with the mean vitrinite reflectance. 20 refs., 15 figs., 4 tabs.

  10. Micrinite maceral evidence of hydrocarbon generation in cretaceous coal measures of the middle Benue trough, Nigeria

    International Nuclear Information System (INIS)

    Obaje, N. G.; Ukpabio, E. J.; Funtua, I. I.

    1999-01-01

    Maceral analysis on samples from the coal and coal-bearing strata of the Awgu Formation in the Middle Benue Trough of Nigeria allows the subdivision of the coal beds and inter seam sediments into three different petrographic/coal facies, namely: a vitrinite-fusinite coal facies which is rich in vitrinite, poor in liptinite, with variable amounts of inertinite and low mineral matter content; a trimaceritic coal facies which is rich in vitrinite, liptinite and inertinite with low mineral matter content; and a shaley coal facies which, expectedly, is dominated by mineral matter and has variable amounts of vitrinite, liptinite and inertinite. Micrinite macerals constitute 8.2% and 4.5 on mineral matter-counted basis in samples from the trimaceritic and shaley coal facies respectively. These amounts, in both cases, are considered to be very high. They occur as finely particulate, rounded grains approximately I um in diameter. Most of the micrinite are closely associated with highly reflecting, almost unrecognizable liptinite. The nature and origin of micrinite and its significance to oil and gas generation have been studied extensively. As secondary macerals, they are generally believed to be relics of oil generation from oil-prone macerals, mainly liptinitic and vitrinitic macerals with which they are closely associated. Reflectance measurements on the associated vitrinite macerals indicate a thermal maturity range of 0.74 - 1.25 % Rm. This range corresponds to the zone of oil generation in most minerogenic oil source rocks. In the study area, however, only the trimaceritic coal facies and some parts of the shaley coal facies that are rich in liptinite alongside the associated micrinite macerals are considered to have generated oil. The vitrinite-fusinite coal facies with its high content of humic organic matter (vitrinite + Inertinite) can only generate gas (wet + dry) within the given thermal maturity range

  11. Notes on the origin of inertinite macerals in coals: Observations on the importance of fungi in the origin of macrinite

    Energy Technology Data Exchange (ETDEWEB)

    Hower, James C. [University of Kentucky Center for Applied Energy Research, 2540 Research Park Drive, Lexington, Kentucky 40511 (United States); O' Keefe, Jennifer M.K. [Department of Physical Sciences, Morehead State University, Morehead, Kentucky 40351 (United States); Watt, Michael A. [Weatherford Laboratories, Arvada, Colorado 80007 (United States); Pratt, Timothy J. [Formerly: Ticora Geosciences, Arvada, Colorado 80007 (United States); Eble, Cortland F. [Kentucky Geological Survey, Lexington, Kentucky 40506 (United States); Stucker, J.D.; Richardson, Allison R. [Department of Earth and Environmental Sciences, University of Kentucky, Lexington, KY 40506 (United States); Kostova, Irena J. [Sofia University ' ' St. Kliment Ohridski' ' , Department of Geology and Paleontology, 15, Tzar Osvoboditel Blvd., 1000 Sofia (Bulgaria)

    2009-11-01

    Macrinite is a, generally, rare inertinite maceral, often incorporating remnants and fragments of other macerals, including vitrinite, liptinite, and other inertinite. The associated inertinites include multiple forms of funginite. Funginite is also commonly found in association with vitrinite of slightly elevated reflectance and with degraded varieties of vitrinite. Together with the highly degraded macrinite, the latter two associations are here inferred to be part of a continuum of fungal and microbial degradation of peat. In any case, the origin of some macrinite is potentially distinct from that of inertinite generated by fire. (author)

  12. Investigating combined influence of petrology and technological parameters on strength of porous coke body

    Energy Technology Data Exchange (ETDEWEB)

    Dinel' t, V.M.; Shkoller, M.B.; Stankevich, A.S.; Korchuganova, G.S.

    1983-09-01

    The VUKhIN branch in Kuznetsk investigated effects of coal petrology and coking conditions on structural strength of coke in blast furnaces. Structural strength of coke produced from black coal from the Kuzbass as well as structural strength of coke partially gasified by carbon dioxide under conditions similar to those in blast furnaces was investigated. Fourteen samples of coal mixtures from the Kuzbass were used. Regression analysis was applied. Equations for forecasting coke properties on the basis of coal petrology and selected parameters characterizing coking were derived. Analyses showed that coke structural strength was decisively influenced by coefficients which characterized the average reflectivity of vitrinite in a coal mixture and its average density. After partial coke gasification by carbon dioxide effects of coefficients which characterized coal mixture nonhomogeneity (fluctuations of vitrinite reflectivity) and coal mixture density increased. Increasing coal density partially compensated negative effects of fluctuations of vitrinite reflectivity on coke structural strength. (10 refs.) (In Russian)

  13. Development and evaluation of an automated reflectance microscope system for the petrographic characterization of bituminous coals

    Energy Technology Data Exchange (ETDEWEB)

    Hoover, D. S.; Davis, A.

    1980-10-01

    The development of automated coal petrographic techniques will lessen the demands on skilled personnel to do routine work. This project is concerned with the development and successful testing of an instrument which will meet these needs. The fundamental differences in reflectance of the three primary maceral groups should enable their differentiation in an automated-reflectance frequency histogram (reflectogram). Consequently, reflected light photometry was chosen as the method for automating coal petrographic analysis. Three generations of an automated system (called Rapid Scan Versions I, II and III) were developed and evaluated for petrographic analysis. Their basic design was that of a reflected-light microscope photometer with an automatic stage, interfaced with a minicomputer. The hardware elements used in the Rapid Scan Version I limited the system's flexibility and presented problems with signal digitization and measurement precision. Rapid Scan Version II was designed to incorporate a new microscope photometer and computer system. A digital stepping stage was incorporated into the Rapid Scan Version III system. The precision of reflectance determination of this system was found to be +- 0.02 percent reflectance. The limiting factor in quantitative interpretation of Rapid Scan reflectograms is the resolution of reflectance populations of the individual maceral groups. Statistical testing indicated that reflectograms were highly reproducible, and a new computer program, PETAN, was written to interpret the curves for vitrinite reflectance parameters ad petrographic.

  14. Monte Carlo simulation of reflection spectra of random multilayer media strongly scattering and absorbing light

    International Nuclear Information System (INIS)

    Meglinskii, I V

    2001-01-01

    The reflection spectra of a multilayer random medium - the human skin - strongly scattering and absorbing light are numerically simulated. The propagation of light in the medium and the absorption spectra are simulated by the stochastic Monte Carlo method, which combines schemes for calculations of real photon trajectories and the statistical weight method. The model takes into account the inhomogeneous spatial distribution of blood vessels, water, and melanin, the degree of blood oxygenation, and the hematocrit index. The attenuation of the incident radiation caused by reflection and refraction at Fresnel boundaries of layers inside the medium is also considered. The simulated reflection spectra are compared with the experimental reflection spectra of the human skin. It is shown that a set of parameters that was used to describe the optical properties of skin layers and their possible variations, despite being far from complete, is nevertheless sufficient for the simulation of the reflection spectra of the human skin and their quantitative analysis. (laser applications and other topics in quantum electronics)

  15. Anatomy of an intruded coal, I: Effect of contact metamorphism on whole-coal geochemistry, Springfield (No. 5) (Pennsylvanian) coal, Illinois Basin

    Energy Technology Data Exchange (ETDEWEB)

    Rimmer, Susan M. [Department of Geology, Southern Illinois University Carbondale, Carbondale, IL 62901 (United States); Yoksoulian, Lois E. [Department of Earth and Environmental Sciences, University of Kentucky, Lexington, KY 40506 (United States); Hower, James C. [Center for Applied Energy Research, University of Kentucky, 2540 Research Park Drive, Lexington, KY 40511 (United States)

    2009-08-01

    If time and heating rate are important agents in coal maturation, one might expect to see differences in chemical changes in response to maturation depending on the means of increased rank. Using a suite of samples obtained from an intruded Pennsylvanian-age coal in southern Illinois, we present whole-coal chemical data. Comparing these data to extant geochemical data for coals that have undergone normal burial maturation, we evaluated the hypothesis that if coal alteration occurs rapidly (due to intrusion) rather than gradually (burial maturation), then different relationships are seen in chemical composition (proximate and ultimate analyses) and vitrinite reflectance. The Pennsylvanian-age (Asturian [Westphalian D]) Springfield (No. 5) coal is mined at the Big Ridge Mine, near Eldorado, southern Illinois. This high volatile B bituminous coal was intruded by an ultramafic igneous intrusion during the early Permian. Alteration occurs out to {proportional_to} 1.2 x dike thickness and includes an increase in random vitrinite reflectance (R{sub m}) from levels {proportional_to} 0.7% to over 5.3%, loss of liptinites, and formation of devolatilization vacuoles and fine mosaic texture. Decreases in volatile matter (VM) and increases in fixed carbon (FC) appear to be less than would be expected for the level of reflectance seen within the alteration halo. Carbonate minerals have a major influence on proximate analyses but even following the removal of carbonates, the decrease in VM is still less than would be seen in coals of similar vitrinite reflectance that were altered by normal burial maturation. Carbonate mineralization also contributes to variability in ultimate analysis values approaching the intrusion, particularly for %C and %O. After carbonate removal, data for these coals do not appear to follow the normal burial coalification tracks when plotted on a van Krevelen diagram and on a Seyler chart. These differences suggest that a slightly different maturation

  16. A partially reflecting random walk on spheres algorithm for electrical impedance tomography

    Energy Technology Data Exchange (ETDEWEB)

    Maire, Sylvain, E-mail: maire@univ-tln.fr [Laboratoire LSIS Equipe Signal et Image, Université du Sud Toulon-Var, Av. Georges Pompidou, BP 56, 83162 La Valette du Var Cedex (France); Simon, Martin, E-mail: simon@math.uni-mainz.de [Institute of Mathematics, Johannes Gutenberg University, 55099 Mainz (Germany)

    2015-12-15

    In this work, we develop a probabilistic estimator for the voltage-to-current map arising in electrical impedance tomography. This novel so-called partially reflecting random walk on spheres estimator enables Monte Carlo methods to compute the voltage-to-current map in an embarrassingly parallel manner, which is an important issue with regard to the corresponding inverse problem. Our method uses the well-known random walk on spheres algorithm inside subdomains where the diffusion coefficient is constant and employs replacement techniques motivated by finite difference discretization to deal with both mixed boundary conditions and interface transmission conditions. We analyze the global bias and the variance of the new estimator both theoretically and experimentally. Subsequently, the variance of the new estimator is considerably reduced via a novel control variate conditional sampling technique which yields a highly efficient hybrid forward solver coupling probabilistic and deterministic algorithms.

  17. Study of Kerogen Maturity using Transmission Fourier Transform Infrared Spectroscopy (FTIR)

    Science.gov (United States)

    Dang, S. T.

    2014-12-01

    Maturity of kerogen in shale governs the productivity and generation hydrocarbon type. There are generally two accepted methods to measure kerogen maturity; one is the measurement of vitrinite reflectance, %Ro, and another is the measurement of Tmax through pyrolysis. However, each of these techniques has its own limits; vitrinite reflectance measurement cannot be applied to marine shale and pre-Silurian shales, which lack plant materials. Furthermore, %Ro, requires the isolation and identification of vitrinite macerals and statistical measurements of at least 50 macerals. Tmax measurement is questionable for mature and post-mature samples. In addition, there are questions involving the effects of solvents on Tmax determinations. Fourier Transmission Infrared Spectroscopy, FTIR, can be applied for both qualitative and quantitative assessment on organics maturity in shale. The technique does not require separating organic matter or identifying macerals. A CH2/CH3 index, RCH, calculated from FTIR spectra is more objective than other measurements. The index increases with maturity (both natural maturation and synthetic maturation through hydrous and dry pyrolysis). The new maturity index RCH can be calibrated to vitrinite reflectance which allows the definition of the following values for levels of maturity: 1) immature—RCH > 1.6±0.2; 2) oil window-- 1.6±0.2 1.3±0.3; 3) wet gas window--1.3±0.3 1.13±0.05; and 4) dry gas window RCH < 1.13±0.05.

  18. Study on maturation process of huminitic organic matter by means of high-pressure experiments

    Energy Technology Data Exchange (ETDEWEB)

    Horvath, Z.A.

    1983-01-01

    Two different series of artificial coalification experiments were made using high pressure bombs. The first series was carried out with a lignite coal of Pliocene age in open and closed systems under the following conditions: duration: one week, load pressure: 1.5 and 10 kbar: temperature: 90, 120, 160 and 200 C, respectively. In the second series of experiments the behaviour of multipopulate vitrinite material in sedimentary rocks was simulated. This was realized by a coal mixture made from four different types of coal of various rank. This starting material was treated under the same conditions as the samples of the first series. The degree of coalification was followed by the random reflectance of the vitrinitic microcomponents of coal. The experimental results show that temperature and duration of the run are the primary factors to increase the rank while the role of load pressure is negligible. The only effect of volatile pressure is to retain the increase of coalification in closed system (as a consequence of the Le Chatelier-Brown principle).

  19. Light-reflection random-target method for measurement of the modulation transfer function of a digital video-camera

    Czech Academy of Sciences Publication Activity Database

    Pospíšil, Jaroslav; Jakubík, P.; Machala, L.

    2005-01-01

    Roč. 116, - (2005), s. 573-585 ISSN 0030-4026 Institutional research plan: CEZ:AV0Z10100522 Keywords : random-target measuring method * light-reflection white - noise target * digital video camera * modulation transfer function * power spectral density Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.395, year: 2005

  20. Paleothermicity in the Central Asturian Coal Basin, North Spain

    Energy Technology Data Exchange (ETDEWEB)

    Piedad-Sanchez, Noe; Izart, Alain; Martinez, Luis; Elie, Marcel; Menetrier, Cedric [UMR G2R/7566-Geologie et Gestion des Ressources Minerales et Energetiques, Equipe Dynamique des Bassins Sedimentaires et des Matieres Organiques, Faculte des Sciences, Universite Henri Poincare, Nancy 1, BP-239, Boulevard des Aiguillettes, 54506 Vandoeuvre-les-Nancy Cedex (France); Suarez-Ruiz, Isabel [Instituto Nacional del Carbon (CSIC), C/ Francisco Pintado Fe, 26, 33011-Oviedo (Spain)

    2004-06-23

    This research shows for the first time maps of vitrinite reflectances and paleotemperatures from the Central Asturian Coal Basin (North Spain) which is a Carboniferous (Pennsylvanian) Basin mainly of Moscovian age. Vitrinite reflectance values decrease from north to south whereas volatile matter distribution increases from south to north. Vitrinite reflectance and volatile matter parameters indicate a coal rank ranging from high volatile bituminous coal in the north, to semianthracite and anthracite in the south. Rock-Eval data show that the organic matter of this basin is Type III kerogen, with a maturation ranging from oil to gas window. Paleotemperatures were calculated by diverse methods using vitrinite reflectance data for different durations of heating and Rock-Eval results. The calculated paleotemperatures and vertical paleotemperature gradients decrease from south to north. The thermal gradient variation in the Central Asturian Coal Basin points to the influence of at least two heating events that affected the organic matter. The first associated with a regular geothermal gradient operating over a long period of time, and the second linked to a southern granitic event of short duration estimated by tectonic data. The short thermal event was located at the end of sedimentation (Late Moscovian and Late Westphalian D) and after folding, but before the overthrusting during the Asturian tectonic phase located before the Early Kasimovian (Cantabrian and Stephanian) deposits. Finally, a simulation of paleotemperatures around the granitic pluton was calculated and compared to maps of paleotemperatures obtained by various methods. These maps refer to an initial depth of one or two km in accordance with the selected methods that are compatible with local erosion. This approach was preferred in order to explain the metamorphism of coal, rather than the hypothesis of hydrothermal fluid flow proposed for other foreland basins. This regional thermal anomaly could be

  1. Source rock potential of middle cretaceous rocks in Southwestern Montana

    Science.gov (United States)

    Dyman, T.S.; Palacas, J.G.; Tysdal, R.G.; Perry, W.J.; Pawlewicz, M.J.

    1996-01-01

    The middle Cretaceous in southwestern Montana is composed of a marine and nonmarine succession of predominantly clastic rocks that were deposited along the western margin of the Western Interior Seaway. In places, middle Cretaceous rocks contain appreciable total organic carbon (TOC), such as 5.59% for the Mowry Shale and 8.11% for the Frontier Formation in the Madison Range. Most samples, however, exhibit less than 1.0% TOC. The genetic or hydrocarbon potential (S1+S2) of all the samples analyzed, except one, yield less than 1 mg HC/g rock, strongly indicating poor potential for generating commercial amounts of hydrocarbons. Out of 51 samples analyzed, only one (a Thermopolis Shale sample from the Snowcrest Range) showed a moderate petroleum potential of 3.1 mg HC/g rock. Most of the middle Cretaceous samples are thermally immature to marginally mature, with vitrinite reflectance ranging from about 0.4 to 0.6% Ro. Maturity is high in the Pioneer Mountains, where vitrinite reflectance averages 3.4% Ro, and at Big Sky Montana, where vitrinite reflectance averages 2.5% Ro. At both localities, high Ro values are due to local heat sources, such as the Pioneer batholith in the Pioneer Mountains.

  2. A study on hydrogen bond in coal macerals with in situ diffuse reflectance FTIR by using a new experimental method

    Energy Technology Data Exchange (ETDEWEB)

    Li, D.T.; Li, W.; Sun, Q.L.; Li, B.Q. [Chinese Academy of Science, Taiyuan (China). Inst. for Coal Chemistry

    2003-04-01

    A new method using the small porcelain as the reactor combined with increasing the flow rate of carrier gas was proposed, which has the advantage of excluding the condensation of volatile produced by heated solid samples on the windows during in situ diffuse reflectance FTIR experiment. Moreover, the feasibility of this method was also discussed. Using this method, the distribution and thermal stability of hydrogen bonds in coal macerals obtained from two coals were studied. The results show that the differences between the distribution of hydrogen bonds formed by hydroxyl group in the macerals of two coals were very similar. For the vitrinites the thermal stability of SH-N, carboxylic acid dimmers and self-associated OH is higher than those in inertinites but for OH-N and hydroxyl tetramers and OH-OR{sub 2} there are no obvious laws. For OH-{pi}, its content increased with increasing temperature to 350-380{sup o}C, and then decreased with further heating. The variation of hydrogen bonds in macerals reflects the difference in their structure.

  3. The organic petrology and thermal maturity of Lower Carboniferous and Upper Devonian source rocks in the Liard Basin, at Jackfish Gap-Yohin Ridge and North Beaver River, northern Canada: Implications for hydrocarbon exploration

    Energy Technology Data Exchange (ETDEWEB)

    Potter, J. (Univ. of Newcastle-upon-Tyne (United Kingdom)); Richards, B.C.; Goodarzi, G. (Geological Survey, Calgary, Alberta (Canada))

    Basinal shales of the Besa River Fm. have TOC values ranging from 1 to 4% and contain abundant type II, dominantly amorphous, kerogen of marine origin. Shales in the Yohin, Clausen, Prophet, and Golata Formations are of mixed maring and terrestrial origins and yield TOC values of 1 to 3%. Kerogen in the Golata and Yohin Formations are dominated by terrestrial components, while the Clausen and Flett kerogen comprises marine liptinites and bitumens. Kerogen from the deltaic Mattson shales at Jackfish Gap are types II and III, having mixed marine and terrestrial origins consistent with shallow, nearshore, subtidal environments. The coals are sapropelic and probably lacustrine in origin. Algal laminites associated with coals in the Upper Mattson have >10% TOC values, while non-laminite shales contain between 2 and 5% TOC. Comparable measured and calculated vitrinite reflectance data indicate that kerogen in the Lower Carboniferous at Jackfish Gap is mature. Kerogen in correlative formations in the subsurface at North Beaver River is more marine. Vitrinites are rate and oxidized, but four populations of bitumens are distinguished on the basis of relative reflectivity and morphological or petrophysical associations. Types A and B bitumens are primary and by-products of hydrocarbon generation from type II (algal and amorphous) kerogens. Correlations between depth and reflectance of bitumens A and B are very good. Vitrinite reflectance data calculated from bitumen reflectance measurements for the Besa River, Prophet, and Golata indicate that they are potential sources of catagenic gas. The Mattson kerogen is mature, oil and gas-prone.

  4. Effect of UV irradiation on cutaneous cicatrices: a randomized, controlled trial with clinical, skin reflectance, histological, immunohistochemical and biochemical evaluations.

    Science.gov (United States)

    Due, Eva; Rossen, Kristian; Sorensen, Lars Tue; Kliem, Anette; Karlsmark, Tonny; Haedersdal, Merete

    2007-01-01

    The aim of this study was to examine the effect of ultraviolet (UV) irradiation on human cutaneous cicatrices. In this randomized, controlled study, dermal punch biopsy wounds served as a wound healing model. Wounds healed by primary or second intention and were randomized to postoperative solar UV irradiation or to no UV exposure. Evaluations after 5 and 12 weeks included blinded clinical assessments, skin reflectance measurements, histology, immunohistochemistry, and biochemical analyses of the N-terminal propeptide from procollagen-1, hydroxyproline, hydroxylysine, and proline. Twelve weeks postoperatively, UV-irradiated cicatrices healing by second intention: (i) were significantly pointed out as the most disfiguring; (ii) obtained significantly higher scores of colour, infiltration and cicatrix area; and (iii) showed significantly higher increase in skin-reflectance measurements of skin-pigmentation vs. non-irradiated cicatrices. No histological, immunohistochemical or biochemical differences were found. In conclusion, postoperative UV exposure aggravates the clinical appearance of cicatrices in humans.

  5. Petrography, palynology, and paleoecology of the Lower Pennsylvanian Bon Air coal, Franklin County, Cumberland Plateau, southeast Tennessee

    Energy Technology Data Exchange (ETDEWEB)

    Shaver, Stephen A.; Saussy, Frederick L. [Department of Forestry and Geology, University of the South, Sewanee, TN 37383 (United States); Eble, Cortland F. [Kentucky Geological Survey, 228 MMRB, University of Kentucky, Lexington, KY 40506-0107 (United States); Hower, James C. [Center for Applied Energy Research, University of Kentucky, 2540 Research Park Drive, Lexington, KY 40511-8433 (United States)

    2006-05-03

    ?15%). Moderately high ash (11.0?20.0%) and low to moderate sulfur (1.24% avg.) are typical, but ash may locally be up to 38% and sulfur up to 2.9%. Volatile matter (32.1?41.3%), calorific value (33.3?34.9 MJ/kg MAF), moisture (2.2?3.4%), and vitrinite reflectance (0.70?0.84% R{sub max}; 0.64?0.79% R{sub random}) place the Bon Air's rank as high-volatile-A bituminous (hvAb). The Armfield coal was probably a channel-distal paleomire, perhaps an oxbow lake or floodplain depression, which domed and then subsided back to planarity prior to burial. Features of its basal and uppermost benches suggest low-lying, often-flooded (but periodically dry) mires marked by fluvial influxes and diverse lycopsid growth. These include variable inertinite, common palynoflora of both small lycopsids (Omphalophloios-like) and large arboreous ones (Lepidophloios and Lepidodendron), minor but significant palynoflora of subaerial levee or levee/mire transition species (especially Paralycopodites), moderate to high ash, variable sulfur, and elevated levels of commonly fluvial trace elements (e.g., Al, Cr, REEs, Rb, Sr, Th, V, Y, and Zr). These benches also contain high total vitrinite, high collotelinite/collodetrinite ratios, and clays with moderate to low kaolinite/quartz ratios, all consistent with the near-neutral pH and limited peat degradation that typify such planar mires. By contrast, middle benches at Armfield reflect mires domed above the land surface, less-often flooded, less-preservational, and of lower pH: coals have lower ash, vitrinite, and collotelinite, less palynoflora of both large arboreous lycopsids and Paralycopodites, and high proportions of kaolinite, liptinite, and Densosporites. Similar data at Shakerag suggest that its mire also grew from planar to domed. However, more abundant Paralycopodites, a kaolinite-poor but quartz-and-illite-rich underclay, benches alternately ash-rich and ash-poor, and an upper bench truncated by channel sandstone, suggest that it was channel

  6. Application of coal petrographic methods in petroleum and natural gas exploration. Anwendung kohlenpetrographischer Methoden bei der Erdoel- und Erdgasprospektion

    Energy Technology Data Exchange (ETDEWEB)

    Teichmueller, M.

    1971-02-15

    The relationship that exists between coalification and the formation of liquid petroleum and natural gas depends entirely upon the temperature in the earth's crust and the duration of heating. The degree of coalification can be determined by reflectivity measurements on very small vitrinitic (huminitic) inclusions in sedimentary rocks, because a satisfactory correlation has been established between mean reflectivity (R/sub m Oil/) and different parameters of chemical rank using 900 vitrites of different rank. This paper reports the considerable experience obtained with this method using cores and cuttings from boreholes of the German oil industry. Subsequently, examples from other countries are described which confirm the applicability of the method. Results obtained so far suggest that oil deposits may occur when the reflectivity (R/sub m Oil/) of the vitrinite lies between 0.3 and 1.0% (brown coal to high-volatile bituminous stage), whereas economic gas deposits may be found when R/sub m Oil/ extends from 0.7 to 2.0% (high-low volatile bituminous stage).

  7. The Influence of Collaborative Reflection and Think-Aloud Protocols on Pre-Service Teachers' Reflection: A Mixed Methods Approach

    Science.gov (United States)

    Epler, Cory M.; Drape, Tiffany A.; Broyles, Thomas W.; Rudd, Rick D.

    2013-01-01

    The purpose of this mixed methods study was to determine if there are differences in pre-service teachers' depth of reflection when using a written self-reflection form, a written self-reflection form and a think-aloud protocol, and collaborative reflection. Twenty-six pre-service teachers were randomly assigned to fourteen teaching teams. The…

  8. Comparative organic petrology of interlayered sandstones, siltstones, mudstones and coals in the Upper Carboniferous Ruhr basin, northwest Germany, and their thermal history and methane generation

    Energy Technology Data Exchange (ETDEWEB)

    Scheidt, G.; Littke, R. (Harress Geotechnik GmbH, Floersheim (Germany, F.R.))

    1989-01-01

    In the coal-mining Ruhr-area, Upper Carboniferous rocks consist of interlayered sandstones, siltstones, mudstones and coals. They were deposited in a tropical, paralic environment where alternating fluvial sedimentation, occasional marine ingressions, and swamp growth resulted in an irregular cyclic succession. The total sedimentary package contains on an average 6 Vol.% of organic manner. About 70 Vol. % of the organic matter occurs in coal seams, the rest as dispersed organic matter in clastic rocks. The organic matter is autochthonous in the coals and allochthonous in associated sandstones and siltstones. It consists of about 70% vitrinite, 20% inertinite, and 10% liptinite. The overall maceral group composition is the same for coals and dispersed organic matter. This surprising similarity is caused by a nearly exclusive input of land-plant derived organic matter to swamps and fluvial systems and a similar degree of preservation. Highest average liptinite contents were found in unrooted mudstones, highest average inertinite contents in coarse-grained siltstones and highest average vitrinite percentages in sandstones. Maturities of the sediments studied are well within the hydrocarbon generation window, e.g. vitrinite reflectivities range from 0.6% to 1.6%. Reflectivities measured on dispersed particles in clastic rocks are similar to those measured in coal seams. Calculations of the amount of methane generated indicate that coal seams contributed more to the total hydrocarbon generation than dispersed organic matter. 51 refs., 13 figs.

  9. Light-reflection random-target method for measurement of the modulation transfer function of a digital video-camera

    Science.gov (United States)

    Pospisil, J.; Jakubik, P.; Machala, L.

    2005-11-01

    This article reports the suggestion, realization and verification of the newly developed measuring means of the noiseless and locally shift-invariant modulation transfer function (MTF) of a digital video camera in a usual incoherent visible region of optical intensity, especially of its combined imaging, detection, sampling and digitizing steps which are influenced by the additive and spatially discrete photodetector, aliasing and quantization noises. Such means relates to the still camera automatic working regime and static two-dimensional spatially continuous light-reflection random target of white-noise property. The introduced theoretical reason for such a random-target method is also performed under exploitation of the proposed simulation model of the linear optical intensity response and possibility to express the resultant MTF by a normalized and smoothed rate of the ascertainable output and input power spectral densities. The random-target and resultant image-data were obtained and processed by means of a processing and evaluational PC with computation programs developed on the basis of MATLAB 6.5E The present examples of results and other obtained results of the performed measurements demonstrate the sufficient repeatability and acceptability of the described method for comparative evaluations of the performance of digital video cameras under various conditions.

  10. Do writing and storytelling skill influence assessment of reflective ability in medical students' written reflections?

    Science.gov (United States)

    Aronson, Louise; Niehaus, Brian; DeVries, Charlie D; Siegel, Jennifer R; O'Sullivan, Patricia S

    2010-10-01

    Increasingly, students are asked to write reflections as part of their medical education, but some question the influence of other factors on the evaluation of these reflections. In this pilot study, the investigators determined whether scores from a validated rubric to measure reflective ability were affected by irrelevant variance resulting from writing or storytelling ability. Students in clerkships wrote reflections on professionalism. All were given identical prompts, with half receiving additional structured guidelines on reflection. Sixty reflections, 30 from each group, were randomly chosen and scored for reflection, writing, and storytelling by trained raters using validated rubrics. There was no correlation between reflection and either writing (r = 0.049, P = .35) or storytelling (r = 0.14, P = .13). The guidelines increased reflection, but not writing or storytelling scores. Reflection is a distinct construct unaffected by learners' writing or storytelling skills. These findings support reflective ability as a distinct skill.

  11. Berau coal in East Kalimantan; Its petrographics characteristics and depositional environment

    Directory of Open Access Journals (Sweden)

    Nana Suwarna

    2014-06-01

    Full Text Available http://dx.doi.org/10.17014/ijog.vol2no4.20071To asses the characteristics of the Early to Middle Miocene Berau coal in the Berau Basin, leading to interpretation of coal depositional environments, some fresh outcrop and subcrop samples and also drill cores of the coals have been analyzed microscopically. Coal petrographic analysis was performed on twenty four coal samples from the Middle Miocene Lati Formation. Vitrinite, present in a high value, and ranging between 66.2 - 96.2%, is dominated by vitrinite B. On the other hand, inertinite and exinite, showing a similar value, exist in a low to moderate amount. Vitrinite reflectance, present in a low value, varies from 0.40 - 0.58%. Low mineral matter content is dominated by clay minerals (0.4 - 6.6% with minor pyrite. Transitions from wet and very wet forested swamps to drier conditions with lower tree density are indicated by the higher content of vitrinite B, whilst a reverse trend is indicated by the lower content of vitrinite A. Petrographic indices obtained from facies diagnostic macerals show that an accumulation of the ancient peats under prevailing relatively wet limited influx clastic marsh to very wet forest swamps or moors is considered. The composition of the coal samples supports the interpretation of a system of fluvial to meandering streams in an upper delta plain environment. The original peat-forming vegetation was composed mainly of cellulose rich, shrub-like plants, tree ferns, herbaceous plant communities, with minor amount of trees. Thereby, the organic facies concept is thus applicable in basin studies context and has potential to become an additional tool for depositional environment interpretation.  

  12. Thermogravimetric analysis in the characterization of colombian coals used in the production of coke

    International Nuclear Information System (INIS)

    Guerrero, Camilo; Salamanca, Monica E; Diaz, Jose de J

    2010-01-01

    Five types of coal from the states of Cundinamarca, Boyaca and Norte de Santander (Colombia) were characterized by proximate, ultimate, rheological, petrographic, calorific and thermogravimetric analysis. The parameters used, especially the ones which determine the rheological properties show that the studied coals and its blends could produce good quality coke. It was observed the inverse relationship between the volatile matter content and the mean vitrinite reflectance, relationship which is attributed to the increase of the aromaticity in the molecular structure of the coal as a consequence of the rank increase. The parameters derived from the thermogravimetric analysis, maximum velocity of de-volatilization and the temperature of maximum velocity of de-volatilization and the media reflectance of the vitrinite showed good correlations. Also was observed an interesting correlation between the velocity of de-volatilization and maximum fluidity. This shows that the thermogravimetric analysis can be a useful tool to characterize in a quick way coals used for metallurgical coke production.

  13. Peer group reflection helps clinical teachers to critically reflect on their teaching.

    Science.gov (United States)

    Boerboom, Tobias B B; Jaarsma, Debbie; Dolmans, Diana H J M; Scherpbier, Albert J J A; Mastenbroek, Nicole J J M; Van Beukelen, Peter

    2011-01-01

    Student evaluations can help clinical teachers to reflect on their teaching skills and find ways to improve their teaching. Studies have shown that the mere presentation of student evaluations is not a sufficient incentive for teachers to critically reflect on their teaching. We evaluated and compared the effectiveness of two feedback facilitation strategies that were identical except for a peer reflection meeting. In this study, 54 clinical teachers were randomly assigned to two feedback strategies. In one strategy, a peer reflection was added as an additional step. All teachers completed a questionnaire evaluating the strategy that they had experienced. We analysed the reflection reports and the evaluation questionnaire. Both strategies stimulated teachers to reflect on feedback and formulate alternative actions for their teaching practice. The teachers who had participated in the peer reflection meeting showed deeper critical reflection and more concrete plans to change their teaching. All feedback strategies were considered effective by the majority of the teachers. Strategies with student feedback and self-assessment stimulated reflection on teaching and helped clinical teachers to formulate plans for improvement. A peer reflection meeting seemed to enhance reflection quality. Further research should establish whether it can have lasting effects on teaching quality.

  14. RMSRo

    DEFF Research Database (Denmark)

    Nielsen, S.B.; Clausen, O.R.; McGregor, Eoin David

    2014-01-01

    Geophysical Research Abstracts Vol. 16, EGU2014-12484, 2014 EGU General Assembly 2014 © Author(s) 2014. CC Attribution 3.0 License. RMSRo: A vitrinite reflectance model consistent with the temperature-apatite fission track system Søren B. Nielsen, Ole R. Clausen, and Eoin D. McGregor Department...

  15. Wave reflections from breakwaters

    OpenAIRE

    Dickson, William S.

    1994-01-01

    A new method is presented for estimating the reflection of a random, multi-directional sea from a coastal structure. The technique is applicable to an array of wave gauges of arbitrary geometry deployed seaward of the reflector. An expansion for small oblique wave incidence angles is used to derive an approximate relationship between measured array cross-spectra and a small number of parameters that describe the incident wave properties and the reflectivity of the structure. Model tests with ...

  16. Liquid hydrocarbon generation potential from Tertiary Nyalau Formation coals in the onshore Sarawak, Eastern Malaysia

    Science.gov (United States)

    Hakimi, Mohammed Hail; Abdullah, Wan Hasiah

    2013-01-01

    Tertiary coals exposed in the north-central part of onshore Sarawak are evaluated, and their depositional environments are interpreted. Total organic carbon contents (TOC) of the coals range from 58.1 to 80.9 wt. % and yield hydrogen index values ranging from 282 to 510 mg HC/g TOC with low oxygen index values, consistent with Type II and mixed Type II-III kerogens. The coal samples have vitrinite reflectance values in the range of 0.47-0.67 Ro %, indicating immature to early mature (initial oil window). T max values range from 428 to 436 °C, which are good in agreement with vitrinite reflectance data. The Tertiary coals are humic and generally dominated by vitrinite, with significant amounts of liptinite and low amounts of inertinite macerals. Good liquid hydrocarbons generation potential can be expected from the coals with rich liptinitic content (>35 %). This is supported by their high hydrogen index of up to 300 mg HC/g TOC and Py-GC ( S 2) pyrograms with n-alkane/alkene doublets extending beyond C30. The Tertiary coals are characterised by dominant odd carbon numbered n-alkanes ( n-C23 to n-C33), high Pr/Ph ratio (6-8), high T m / T s ratio (8-16), and predominant regular sterane C29. All biomarkers parameters clearly indicate that the organic matter was derived from terrestrial inputs and the deposited under oxic condition.

  17. Modified polarized geometrical attenuation model for bidirectional reflection distribution function based on random surface microfacet theory.

    Science.gov (United States)

    Liu, Hong; Zhu, Jingping; Wang, Kai

    2015-08-24

    The geometrical attenuation model given by Blinn was widely used in the geometrical optics bidirectional reflectance distribution function (BRDF) models. Blinn's geometrical attenuation model based on symmetrical V-groove assumption and ray scalar theory causes obvious inaccuracies in BRDF curves and negatives the effects of polarization. Aiming at these questions, a modified polarized geometrical attenuation model based on random surface microfacet theory is presented by combining of masking and shadowing effects and polarized effect. The p-polarized, s-polarized and unpolarized geometrical attenuation functions are given in their separate expressions and are validated with experimental data of two samples. It shows that the modified polarized geometrical attenuation function reaches better physical rationality, improves the precision of BRDF model, and widens the applications for different polarization.

  18. Composition of coal tar from pyrolysis and hydropyrolysis of Shenmu coal macerals

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Q.; Li, W.; Chen, H.; Li, B. [Shandong Academy of Sciences, Jinan (China)

    2005-08-15

    To understand the relationship of the tar compositions and the coal macerals, the tars obtained from the pyrolysis and hydropyrolysis of Shenmu coal macerals in a fixed-bed reactor were analysed using GC-MS. And the effects of petrographic component, atmosphere and pressure on the yield of aromatic hydrocarbon, phenols, hydrocarbons, oxygen-containing heterocycle and PAHs were systematically investigated. The results show that there is great difference in the composition and the relative content of long chain hydrocarbons, aromatic hydrocarbons, phenols, oxygen-containing heterocycle and PAHs in tars from vitrinite and inertinite pyrolysis. Vitrinite tar contains high content of hydrocarbon with long chain, and inertinite tar contains high content of aromatic hydrocarbons, phenols, oxygen-containing heterocycle and PAHs. It suggests that vitrinite has lower aromaticity and longer chain in its structure than inertinite, which is in well agreement with the result from {sup 13}C NMR and FT-IR test. The tar yield of hydropyrolysis is higher than that of pyrolysis. With increasing the hydrogen pressure, the yield of tar increases greatly. The content of phenols and naphthalene in vitrinite tar form hydropyrolysis under 0.1 MPa is much lower than that form pyrolysis, while that of inertinite tar changes a little. The difference of tar compositions and relative content during pyrolysis and hydropyrolysis reflects the effect of hydrogenation and hydrocracking reactions and the structure characteristics of the macerals. 12 refs., 3 figs.

  19. A geological evidence of very low frequency earthquake inferred from vitrinite thermal records across a microfault within on-land accretionary complex.

    Science.gov (United States)

    Morita, K.; Hashimoto, Y.; Hirose, T.; Hamada, Y.; Kitamura, M.

    2014-12-01

    Generation of friction heat associated with fault slip is controlled by friction, slip distance and fault thickness. Nature of fault slip can be estimated from the record of frictional heating along a fault (e.g., Fulton et al., 2012). Purpose of this study is to detect the record of frictional heating along a microfault observed in on-land accretionary complex, Shimanto Belt, SW Japan using vitrinite reflectance (Ro) and to examine the characteristics of fault slip in deeper subduction zone. The study area is located in Nonokawa formation, the Cretaceous Shimanto Belt, in Kochi Prefecture, Southwest Japan. We found a carbonaceous material concentrated layer (CMCL) in the formation. Some micro-faults cut the layer. The thickness of CMCL is about 3-4m. Ro of host rock is about 0.98-1.1% and of fault rock is over 1.2%. Kitamura et al. (2012) pointed out that fracturing energy may control the high Ro within fault zone. To avoid the effect of fracturing on Ro, we tired to detect a diffusion pattern of frictional heating in host rocks. Distribution of Ro is mapped in thin sections to make the Ro-distance pattern perpendicular to the fault plane. Within the fracture zone, abnormally high Ro (about 2.0% or above) was observed. Ro was 1.25% at the wall of fracture zone and decreases to 1.1% at about 5cm from the wall. We interpreted that the Ro-distance pattern was resulted from the thermal diffusion. Using this diffusion pattern, the characteristic fault parameters, such as friction, slip rate and rise time (Tr) was examined. We set parameters Q (= friction times slip rate). We have simulated frictional heating and Ro maturation on the basis of the method by Sweeny and Burnham (1990). Grid search was conducted to find the best fitted combination of Q and Tr at the smallest residual between simulated Ro and observed Ro. In the result, we estimated about 1500 (Pa m/s) of Q and about 130000(s) of Tr. Because the base temperature is about 185˚C based on the 1.1% of Ro, the

  20. Modeling Bidirectional Reflectance Distribution Function of One-dimensional Random Rough Surfaces with the Finite Difference Time Domain Method

    Directory of Open Access Journals (Sweden)

    Min-Jhong Gu

    2014-08-01

    Full Text Available This article describes the development of a suite of programs that is capable of simulating the radiation properties of a random rough surface (RRS. The fundamental approach involves the generation, by fast Fourier transform (FFT built with rigorous finite difference time domain (FDTD, as the theoretical basis for the simulation of a bidirectional reflectance distribution function (BRDF of the RRS. The results are compared with the measurements and modeling of existing work to verify the feasibility of customized programming. It was found that the results of this study were a better match to the measurement data than those achieved in other modeling work.

  1. Map showing thermal-alteration indicies in roadless areas and the Santa Lucia Wilderness in the Los Padres National Forest, Southwestern California

    Science.gov (United States)

    Frederiksen, N.O.

    1985-01-01

    This map shows thermal-alteration indices (TAI's), based on colors of pollen grains, of 115 outcrop and 20 conventional core samples from Mesozoic and lower Tertiary rocks in the southern Coast and western Transverse Ranges, Southwestern California. The TAI's have been calibrated against previously determined vitrinite reflectance values from some of the same sample localities.

  2. Bidirectional reflectance distribution function of Spectralon white reflectance standard illuminated by incoherent unpolarized and plane-polarized light.

    Science.gov (United States)

    Bhandari, Anak; Hamre, Børge; Frette, Øvynd; Zhao, Lu; Stamnes, Jakob J; Kildemo, Morten

    2011-06-01

    A Lambert surface would appear equally bright from all observation directions regardless of the illumination direction. However, the reflection from a randomly scattering object generally has directional variation, which can be described in terms of the bidirectional reflectance distribution function (BRDF). We measured the BRDF of a Spectralon white reflectance standard for incoherent illumination at 405 and 680 nm with unpolarized and plane-polarized light from different directions of incidence. Our measurements show deviations of the BRDF for the Spectralon white reflectance standard from that of a Lambertian reflector that depend both on the angle of incidence and the polarization states of the incident light and detected light. The non-Lambertian reflection characteristics were found to increase more toward the direction of specular reflection as the angle of incidence gets larger.

  3. Genetic-industrial classification of brown coals in Serbia

    Energy Technology Data Exchange (ETDEWEB)

    Ercegovac, Marko [Serbian Academy of Sciences and Arts, Knez Mihailova 35, 11000 Belgrade (Serbia and Montenegro); ?ivotic, Dragana; Kostic, Aleksandar [University of Belgrade, Faculty of Mining and Geology, Djusina 7, 11000 Belgrade (Serbia and Montenegro)

    2006-08-01

    The petrologic, chemical and technological features of low-rank coals from nineteen of the most important basins in Serbia have been studied as part of the research project of genetic-industrial classification of low-rank coals of Serbia. Most of these features have been included as parameters of the codification system for low-rank coals. The paper discusses the main genetic, technological and supplementary parameters of the Serbian brown coals such as rank, petrographic composition, gelification degree, total moisture, ash content, sulphur content, calorific value, tar yield, the chemical composition and the thermotechnical properties of ash. The rank of brown coals from Serbia has been defined on the basis of the following parameters: random reflectance of huminite/vitrinite (R{sub r}=0.26-0.50%), total moisture (W{sup ar}=13.18-49.11%), gross calorific value (Q{sup daf}=22.3-29.2MJ/kg, dry, ash-free basis), net calorific value (Q{sup daf}=21.2-28.1MJ/kg, dry, ash-free basis). The results from the maceral analysis confirm that the humic coals, in general, are characterized by high huminite content (76.0-97.9vol.%, mineral matter free), low inertinite amount (0.7-6.3vol.%, mineral matter free), and a variable amount of liptinite (0.8-15.5vol.%, mineral matter free). It is possible to define three groups of Serbian brown coals on the basis of the primary, or genetic parameters, technological, or chemical parameters, and supplementary parameters: soft (Low-Rank C; [Economic Commission for Europe, Committee on Sustainable Energy- United Nations (ECE-UN), 1998. International Classification of in-Seam Coals. Energy 19, 41 pp.; Economic Commission for Europe, Committee on Sustainable Energy- United Nations (ECE-UN), 1999. International Codification System for Low-Rank Coals. Energy 9, 19 pp.; Economic Commission for Europe, Committee on Sustainable Energy- United Nations (ECE-UN), 2000. International Classification for Low-Rank Coals. Energy 12, 21 pp.]), dull (Low

  4. Reconstruction of the paleothermal history of the sub-basin, Lower Guajira, Colombia

    International Nuclear Information System (INIS)

    Garcia Gonzalez, Mario; Mier Umana, Ricardo; Cruz Guevara, Luis Enrique

    2010-01-01

    The paleothermal history of the lower Guajira sub-basin was achieved using three methods: 1) calculation of the presents geothermal gradient and heat flow, 2) vitrinite reflectance and, 3) fission track analysis on apatites and zircon grains. New analytical data of vitrinite reflectance and fission tracks allowed identifying four thermal events with the following features: the oldest thermal event took place during the late cretaceous between 95 and 65 ma. The second thermal event occurred during the late Eocene between 40 and 35 ma. The third thermal event occurred in the early and middle Miocene between 22 and 15 ma. The fourth and last thermal event took place in the late Miocene between 10 and 5 ma. The cooling events match with four unconformities previously identified: 1) the late cretaceous unconformity at the top of the Guaralamai Formation, 2) the late Eocene unconformity at the base of the Siamana Formation 3) the early to middle Miocene unconformity on the top of the Siamana Formation, and 4) the late Miocene unconformity on the top of the Castilletes Formation.

  5. Effect of aperiodicity on the broadband reflection of silicon nanorod structures for photovoltaics.

    Science.gov (United States)

    Lin, Chenxi; Huang, Ningfeng; Povinelli, Michelle L

    2012-01-02

    We carry out a systematic numerical study of the effects of aperiodicity on silicon nanorod anti-reflection structures. We use the scattering matrix method to calculate the average reflection loss over the solar spectrum for periodic and aperiodic arrangements of nanorods. We find that aperiodicity can either improve or deteriorate the anti-reflection performance, depending on the nanorod diameter. We use a guided random-walk algorithm to design optimal aperiodic structures that exhibit lower reflection loss than both optimal periodic and random aperiodic structures.

  6. The coalification profile of the Grambach 1 exploration well - first indication of an oil kitchen in the molasse basin. Das Inkohlungsprofil der Bohrung Grambach 1 - erster Hinweis auf eine ''Oelkueche'' im Molassebecken

    Energy Technology Data Exchange (ETDEWEB)

    Hiltmann, W.; Wehner, H. (Bundesanstalt fuer Geowissenschaften und Rohstoffe, Hannover (Germany)); Kuckelkorn, K. (Niedersaechsisches Landesamt fuer Bodenforschung, Hannover (Germany))

    1999-06-01

    For the first time an exploration well beneath the German part of the Alpine overthrust zone met vitrinite reflectance values raising up to 1,6% R[sub r] - and this in a widespread tectonic high position. The interpretation as an oil and gas kitchen is confirmed by oil maturity (derived by biomarkers and carbon isotope ratios). (orig.)

  7. A uranium-bearing coalificated wood remain from the Upper Carboniferous uranium ore deposit in the Baden-Baden region of the Black Forest

    International Nuclear Information System (INIS)

    Kirchheimer, F.

    1981-01-01

    From the 1973 discovered Upper Carboniferous uranium ore sandstone deposit in the Baden-Baden region (Black Forest) a uranium-bearing coalificated wood remain derived, probably the relic of a Cordaites-trunk. The chemical determinated whole uranium content of this amounts about to 40 wght.-%. Pitchblende of the collomorphic type is embedded in the vitrinite of the fossil and imitates the nearly destroyed former wood-structure. The aggregates of this mineral, surrounded by zones of contact, consist of at least two modifications of different reflectance and hardness. Radiometric analyses reveale a different disturbed radioactive equilibrium, which indicated partly loss and re-enrichment of the uranium-content in recent time. A part of the fossil is completely mineralized by pitchblende of high reflectance and associated galena. For this paragenesis the radiometric investigations proved an approached equilibrium of radioactive substances. Therefore it is to be estimated, that the pitchblende is not alterated substantially, in contrast to the embeddings in the vitrinite, rich in little reflecting and soft nasturanium. The inhomogenic mineralization of the highly coalificated fossil, also to recognise microscopically, is set in relation to the controverse genetic interpretation of the deposit. Final remarks are concerned to other uranium-enriched fossils, especially remains of bones of different origin and age. (orig.) [de

  8. Quantum random number generator

    Science.gov (United States)

    Soubusta, Jan; Haderka, Ondrej; Hendrych, Martin

    2001-03-01

    Since reflection or transmission of a quantum particle on a beamsplitter is inherently random quantum process, a device built on this principle does not suffer from drawbacks of neither pseudo-random computer generators or classical noise sources. Nevertheless, a number of physical conditions necessary for high quality random numbers generation must be satisfied. Luckily, in quantum optics realization they can be well controlled. We present an easy random number generator based on the division of weak light pulses on a beamsplitter. The randomness of the generated bit stream is supported by passing the data through series of 15 statistical test. The device generates at a rate of 109.7 kbit/s.

  9. Demonstrating quantum random with single photons

    International Nuclear Information System (INIS)

    Bronner, Patrick; Strunz, Andreas; Meyn, Jan-Peter; Silberhorn, Christine

    2009-01-01

    We present an experiment for education which demonstrates random transmission or reflection of heralded single photons on beam splitters. With our set-up, we can realize different quantum random experiments by appropriate settings of polarization rotators. The concept of entanglement is motivated by correlated randomness. The experiments are suitable for undergraduate education and are available as interactive screen experiments.

  10. Digital random-number generator

    Science.gov (United States)

    Brocker, D. H.

    1973-01-01

    For binary digit array of N bits, use N noise sources to feed N nonlinear operators; each flip-flop in digit array is set by nonlinear operator to reflect whether amplitude of generator which feeds it is above or below mean value of generated noise. Fixed-point uniform distribution random number generation method can also be used to generate random numbers with other than uniform distribution.

  11. Asymmetric training using virtual reality reflection equipment and the enhancement of upper limb function in stroke patients: a randomized controlled trial.

    Science.gov (United States)

    Lee, DongJin; Lee, MyungMo; Lee, KyoungJin; Song, ChangHo

    2014-07-01

    Asymmetric movements with both hands contributed to the improvement of spatially coupled motion. Thus, the aim of this study was to investigate the effects of an asymmetric training program using virtual reality reflection equipment on upper limb function in stroke patients. Twenty-four stroke patients were randomly allocated to an experimental group (n=12) or a control group (n=12). Both groups participated in conventional physical therapy for 2×30 min/d, 5 d/wk, for 4 weeks. The experimental group also participated in an asymmetric training program using virtual reality reflection equipment, and the control group participated in a symmetric training program. Both asymmetric and symmetric programs were conducted for 30 min/d, 5 d/wk, for 4 weeks. To compare upper limb function before and after intervention, the Fugl-Meyer Assessment (FMA), the Box and Block Test (BBT), grip strength, range of motion (ROM), and spasticity were assessed. Both groups showed significant increases in upper limb function, excepting spasticity, after intervention (Pinteraction was demonstrated only for shoulder/elbow/wrist items of FMA, BBT, grip strength, and ROM of wrist flexion, extension, and ulnar deviation (Pvirtual reality reflection equipment is an effective intervention method for improving upper limb function in stroke patients. We consider that an additional study based on a program using virtual reflection, which is more functional than performing simple tasks, and consisting of tasks relevant to the activities of daily living be conducted. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  12. Clinical linguistics: conversational reflections.

    Science.gov (United States)

    Crystal, David

    2013-04-01

    This is a report of the main points I made in an informal "conversation" with Paul Fletcher and the audience at the 14th ICPLA conference in Cork. The observations arose randomly, as part of an unstructured 1-h Q&A, so they do not provide a systematic account of the subject, but simply reflect the issues which were raised by the conference participants during that time.

  13. Self-reflection, gender and science achievement

    Science.gov (United States)

    Shoop, Kathleen A.

    Drawing on socio-cognitive learning theory, this study compared achievement scores of 134 male and female high school biology students randomly assigned to groups which either used self-reflection, used self-reflection and received feedback, or did not self-reflect. Following a pretest, the teacher provided self-reflection strategy instruction to students in the two intervention groups and then subsequently provided in-class self-reflection time for these groups. The posttest concluded the unit; the retention measure was five weeks later. A quasi-experimental 3 x 3 x 2 (time x intervention x gender) factorial repeated-measures control group design was used for this study; a repeated measures ANOVA and several one-way ANOVA's were used to answer the research questions. Results from the repeated-measures ANOVA revealed significant results for Time and Time x Intervention, with the reflection group demonstrating significantly lower gains from pretest to posttest than the other two groups. The ANOVA examining differences between those who reflected and those who reflected and received feedback provided significant results with similar results for the difference between the control group and the reflection group. For teachers and students this study provides several areas of practical significance. Primarily, teachers may find lower student achievement if students regularly self-reflect but do not receive feedback for their reflection.

  14. Polarizer reflectivity variations

    International Nuclear Information System (INIS)

    Ozarski, R.G.; Prior, J.

    1980-01-01

    On Shiva the beam energy along the chain is monitored using available reflections and/or transmission through beam steering, splitting, and polarizing optics without the intrusion of any additional glass for diagnostics. On the preamp table the diagnostic signal is obtained from the signal transmitted through turning mirrors. At the input of each chain the signal is obtained from the transmission through one of the mirrors used for the chain input alignment sensor (CHIP). At the chain output the transmission through the final turning mirror is used. These diagnostics have proved stable and reliable. However, one of the prime diagnostic locations is at the output of the beta rod. The energy at this location is measured by collecting small reflections from the last polarizer surface of the beta Pockels cell polarizer package. Unfortunately, calibration of this diagnostic has varied randomly, seldom remaining stable for a week or more. The cause of this fluctuation has been investigated for the past year and'it has been discovered that polarizer reflectivity varies with humidity. This report will deal with the possible causes that were investigated, the evidence that humidity is causing the variation, and the associated mechanism

  15. Petrography and rank of the Bhangtar coals, southeastern Bhutan

    Energy Technology Data Exchange (ETDEWEB)

    Pareek, H S [BH23, Meerut (India)

    1990-07-01

    In Bhutan, a potential coal deposit is exposed at Bhangtar in the 'landslide zone'. Nineteen coal seams are encountered in this area, and occur in the Lower Gondwana Supergroup preserved in between the Main Boundary Fault and the Thrust. The coal is low in moisture, {lt}1.76%, but the coal cores show moisture values of 3.16%. The ash content is up to 48.87% and increases substantially in the younger seams. The volatile content (on a pure coal basis) ranges from 23.38% to 41.02%. The sulphur content is less than 0.61%. The coals are non-coking. The amount of trace elements in the coal is quite low. The average petrographic composition of the Bhangtar coal is vitrinite - 31%, exinite - 2%, inertinite - 31%, and mineral and shaly matter - 36%, the vitrinite proportion decreases from the older to the younger seams, which are shaly. an age can be assigned to the Bhangtar coal. Based on oil reflectance, the rank of the coal is metalignitous to hypobituminous. The average microlithotype composition of the coal is vitrite - 30%, clarite - 1%, vitrinertite V - 14%, vitrinertite I - 11%, durite - 3%, fusite - 14%, and carbominerite - 27%. Vitrite decreases in proportion towards the younger seams, 'intermediates' show a concomitant increase, while durite and fusite remain constant. Carbonaceous shale contains fragmentary inertinite and vitrinite macerals and is interlayered with micro-bands of shaly coal which is characterised by abundant fragments of fusinite and vitrinite. The coal is very fragile and thus amenable to economic beneficiation. The coal is used as fuel in electric power plants. The Bhangtar coal is characteristically distinct from the Gondwana coals of India in petrography and rank, but correlates petrographically with the Kameng coals of Arunachal Pradesh, India. 18 refs., 4 figs., 8 tabs., 3 plates.

  16. Sputtering and reflection of self-bombardment of tungsten material

    International Nuclear Information System (INIS)

    Niu, Guo-jian; Li, Xiao-chun; Xu, Qian; Yang, Zhong-shi; Luo, Guang-nan

    2015-01-01

    In present research, the sputtering and reflection yield of self-bombardment of tungsten are investigated with the aid of molecular dynamics simulations. The source of sputtered and reflected atoms is detected by traced the original locations of sputtered and reflected atoms. Results show that for the reflected atoms no specific region exists which means cluster atoms are randomly reflected. But almost all of sputtered atoms are from a conical region under the landing point of cluster. So we can determine the sputtering yield by study the dimension of the sputtering region. Molecular dynamics shows the depth and radius of the conical are power functions of impacting energy. The effects of cluster size and temperature of target on sputtering and reflection rate are also preformed in present study. Both sputtering and reflection yield are proportion to cluster size in present cluster size, i.e. 66–2647 atoms. Higher target temperature can increase sputtering yield and deduce sputtering threshold energy, but little effect on reflection rate

  17. Sputtering and reflection of self-bombardment of tungsten material

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Guo-jian [University of Science and Technology of China, Hefei (China); Institute of Plasma Physics Chinese Academy of Sciences, Hefei (China); Li, Xiao-chun; Xu, Qian; Yang, Zhong-shi [Institute of Plasma Physics Chinese Academy of Sciences, Hefei (China); Luo, Guang-nan, E-mail: gnluo@ipp.ac.cn [University of Science and Technology of China, Hefei (China); Institute of Plasma Physics Chinese Academy of Sciences, Hefei (China); Hefei Center for Physical Science and Technology, Hefei (China); Hefei Science Center of CAS, Hefei (China)

    2015-04-15

    In present research, the sputtering and reflection yield of self-bombardment of tungsten are investigated with the aid of molecular dynamics simulations. The source of sputtered and reflected atoms is detected by traced the original locations of sputtered and reflected atoms. Results show that for the reflected atoms no specific region exists which means cluster atoms are randomly reflected. But almost all of sputtered atoms are from a conical region under the landing point of cluster. So we can determine the sputtering yield by study the dimension of the sputtering region. Molecular dynamics shows the depth and radius of the conical are power functions of impacting energy. The effects of cluster size and temperature of target on sputtering and reflection rate are also preformed in present study. Both sputtering and reflection yield are proportion to cluster size in present cluster size, i.e. 66–2647 atoms. Higher target temperature can increase sputtering yield and deduce sputtering threshold energy, but little effect on reflection rate.

  18. Analysis of the relationship between the coal properties and their liquefaction characteristics by using the coal data base; Tanshu data base ni yoru tanshitsu to ekika tokusei no kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Kanbayashi, Y.; Okada, K. [Coal Mining Research Center, Tokyo (Japan)

    1996-10-28

    The relationship between coal properties and liquefaction or gasification characteristics was analyzed by using the analysis and test results and liquefaction characteristics in the coal data base. On liquefaction reaction, the close relation between an oil yield and coal constituent composition or a coal rank is well-known. Various multivariable regression analyses were conducted by using 6 factors as variables such as calorific value, volatile component, O/C and H/C atomic ratios, exinite+vitrinite content and vitrinite reflectance, and liquefaction characteristics as variate. On liquefaction characteristics, the oil yield of dehydrated and deashed coals, asphaltene yield, hydrogen consumption, produced water and gas quantities, and oil+asphaltene yield were predicted. The theoretical gasification efficiency of each specimen was calculated to evaluate the liquefaction reaction obtained. As a result, the oil yield increased with H/C atomic ratio, while the theoretical gasification efficiency increased with O/C atomic ratio. 5 figs., 1 tab.

  19. A brief petrographic review on Nigerian coal resources

    International Nuclear Information System (INIS)

    Obaje, N. G.; Abaa, S. I.; Najime, T.; Suh, C. E.

    2000-01-01

    The coal resources of Nigeria are located mainly within the Benue Trough. In the lower Benue, subbituminous coals occur within the Maastrichtian Mamu Formation. High - volatile bituminous coals are found within the Turonian - Santonian Awgu Formation in the middle Benue while the upper Benue contains lignites and sub-bituminous coals in the Maastrichtian Gombe Sandstone Formation. Maceral analyses show that himinite dominates in the petrographic composition of the lower and upper Benue Trough coals with vitrinite reflectance values ranging from 0.30 to 0.63% Rm. In coals from the middle Benue, vitrinite macerals predominate and Rm values range from 0.74 to 1.25%. The present review suggests that the sub-bituminous coals in the lower and upper Benue are optimum for combustion and sub-optimum for liquefaction; while the high-volatile bituminous coals in the middle Benue, apart form being optimum for liquefaction, are the most suitable as raw material for coke making (carbonization) in steel manufacture

  20. Mindfulness Plus Reflection Training: Effects on Executive Function in Early Childhood

    Directory of Open Access Journals (Sweden)

    Philip David Zelazo

    2018-02-01

    Full Text Available Executive function (EF skills are essential for academic achievement, and poverty-related stress interferes with their development. This pre-test, post-test, follow-up randomized-control trial assessed the impact of an intervention targeting reflection and stress reduction on children's EF skills. Preschool children (N = 218 from schools serving low-income families in two U.S. cities were randomly assigned to one of three options delivered in 30 small-group sessions over 6 weeks: Mindfulness + Reflection training; Literacy training; or Business as Usual (BAU. Sessions were conducted by local teachers trained in a literacy curriculum or Mindfulness + Reflection intervention, which involved calming activities and games that provided opportunities to practice reflection in the context of goal-directed problem solving. EF improved in all groups, but planned contrasts indicated that the Mindfulness + Reflection group significantly outperformed the BAU group at Follow-up (4 weeks post-test. No differences in EF were observed between the BAU and Literacy training groups. Results suggest that a brief, small-group, school-based intervention teaching mindfulness and reflection did not improve EF skills more than literacy training but is promising compared to BAU for improving EF in low-income preschool children several weeks following the intervention.

  1. Investigation of hydropyrolysis behaviour of Shenmu macerals by TG-MS

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Q.; Li, W.; Chen, H.; Li, B. [Analysis and Test Center, Shandong Academy of Sciences, Jinan (China)

    2004-12-01

    The hydropyrolysis characteristics of Shenmu coal and its macerals were investigated using TG-151 thermo balance, and the evolved gases were on-line analyzed by mass spectroscopy. The results show that vitrinite has higher volatile yield, maximum weight loss rate and lower peak temperature. Vitrinite produces more C{sub 1} - C{sub 4} lighter hydrocarbons and C{sub 5} - C{sub 8} aromatic hydrocarbons than inertinite. Vitrinite has a higher water yield, which is consistent with that the vitrinite has higher phenolic-OH content. The difference in the evolved gases and water between pyrolysis and hydropyrolysis shows the effect of hydrogenation and hydrocracking during hydropyolysis. 11 refs., 4 figs., 1 tab.

  2. Investigation of omnidirectional reflection band in ZnTe/ZnSe distributed Bragg reflector

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Ying-Shin [Department of Electrical Engineering, National Taiwan Ocean University, Keelung 20224, Taiwan (China); Hu, Sheng-Yao [Department of Digital Technology Design, Tungfang Design University, Kaohsiung 82941, Taiwan (China); Lee, Yueh-Chien, E-mail: jacklee@mail.tnu.edu.tw [Department of Electronic Engineering, Tungnan University, New Taipei City 22202, Taiwan (China); Chang, Chung-Cheng; Tiong, Kwong-Kau [Department of Electrical Engineering, National Taiwan Ocean University, Keelung 20224, Taiwan (China); Shen, Ji-Lin [Department of Physics, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Chou, Wu-Ching [Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan (China)

    2015-11-15

    We report the characteristics of reflectance spectra of the 15- and 20-period ZnTe/ZnSe distributed Bragg reflector grown on GaAs (001) substrates by molecular beam epitaxy. The reflectance spectra measured at various incident angles and polarizations were investigated by the theoretical curves simulated using transfer matrix method. The wavelength variation of the refractive indices described by Sellmeier equation and random thickness model were also considered for the interpretation of the experimentally observed curves. An omnidirectional reflection range defined from the edge of incident-angle-dependent reflection band with TE and TM polarizations is about 15 nm, and is consistent with the observed experimental curves. The results showed that the selected ZnTe and ZnSe materials are suitable for constructing multilayer structures having omnidirectional reflection band. - Highlights: • ZnTe/ZnSe distributed Bragg reflector grown by molecular beam epitaxy. • The reflectance spectra are measured at various incidence angles and polarizations. • The theoretical curves are considered by Sellmeier and random thickness models. • An observed omnidirectional reflection range in ZnTe/ZnSe DBR is about 15 nm.

  3. Thermal-maturity limit for primary thermogenic-gas generation from humic coals as determined by hydrous pyrolysis

    Science.gov (United States)

    Lewan, Michael; Kotarba, M.J.

    2014-01-01

    Hydrous-pyrolysis experiments at 360°C (680°F) for 72 h were conducted on 53 humic coals representing ranks from lignite through anthracite to determine the upper maturity limit for hydrocarbon-gas generation from their kerogen and associated bitumen (i.e., primary gas generation). These experimental conditions are below those needed for oil cracking to ensure that generated gas was not derived from the decomposition of expelled oil generated from some of the coals (i.e., secondary gas generation). Experimental results showed that generation of hydrocarbon gas ends before a vitrinite reflectance of 2.0%. This reflectance is equivalent to Rock-Eval maximum-yield temperature and hydrogen indices (HIs) of 555°C (1031°F) and 35 mg/g total organic carbon (TOC), respectively. At these maturity levels, essentially no soluble bitumen is present in the coals before or after hydrous pyrolysis. The equivalent kerogen atomic H/C ratio is 0.50 at the primary gas-generation limit and indicates that no alkyl moieties are remaining to source hydrocarbon gases. The convergence of atomic H/C ratios of type-II and -I kerogen to this same value at a reflectance of indicates that the primary gas-generation limits for humic coal and type-III kerogen also apply to oil-prone kerogen. Although gas generation from source rocks does not exceed vitrinite reflectance values greater than , trapped hydrocarbon gases can remain stable at higher reflectance values. Distinguishing trapped gas from generated gas in hydrous-pyrolysis experiments is readily determined by of the hydrocarbon gases when a -depleted water is used in the experiments. Water serves as a source of hydrogen in hydrous pyrolysis and, as a result, the use of -depleted water is reflected in the generated gases but not pre-existing trapped gases.

  4. Classification of huminite-ICCP System 1994

    Energy Technology Data Exchange (ETDEWEB)

    Sykorova, I. [Institute of Rock Structure and Mechanics, Academy of Science of the Czech Republic, V Holesovicka 41, 182 09 Prague 8 (Czech Republic); Pickel, W. [Coal and Organic Petrology Services Pty Ltd, 23/80 Box Road, Taren Point, NSW 2229 (Australia); Christanis, K. [Department of Geology, University of Patras, 26500 Rio-Patras (Greece); Wolf, M. [Mergelskull 29, 47802 Krefeld (Germany); Taylor, G.H. [15 Hawkesbury Cres, Farrer Act 2607 (Australia); Flores, D. [Departamento de Geologia, Faculdade de Ciencias do Porto, Praca de Gomes Teixeira, 4099-002 Porto (Portugal)

    2005-04-12

    In the new classification (ICCP System 1994), the maceral group huminite has been revised from the previous classification (ICCP, 1971. Int. Handbook Coal Petr., suppl. to 2nd ed.) to accommodate the nomenclature to changes in the other maceral groups, especially the changes in the vitrinite classification (ICCP, 1998. The new vitrinite classification (ICCP System 1994). Fuel 77, 349-358.). The vitrinite and huminite systems have been correlated so that down to the level of sub-maceral groups, the two systems can be used in parallel. At the level of macerals and for finer classifications, the analyst now has, according to the nature of the coal and the purpose of the analysis, a choice of using either of the two classification systems for huminite and vitrinite. This is in accordance with the new ISO Coal Classification that covers low rank coals as well and allows for the simultaneous use of the huminite and vitrinite nomenclature for low rank coals.

  5. Closed-form solution for the Wigner phase-space distribution function for diffuse reflection and small-angle scattering in a random medium.

    Science.gov (United States)

    Yura, H T; Thrane, L; Andersen, P E

    2000-12-01

    Within the paraxial approximation, a closed-form solution for the Wigner phase-space distribution function is derived for diffuse reflection and small-angle scattering in a random medium. This solution is based on the extended Huygens-Fresnel principle for the optical field, which is widely used in studies of wave propagation through random media. The results are general in that they apply to both an arbitrary small-angle volume scattering function, and arbitrary (real) ABCD optical systems. Furthermore, they are valid in both the single- and multiple-scattering regimes. Some general features of the Wigner phase-space distribution function are discussed, and analytic results are obtained for various types of scattering functions in the asymptotic limit s > 1, where s is the optical depth. In particular, explicit results are presented for optical coherence tomography (OCT) systems. On this basis, a novel way of creating OCT images based on measurements of the momentum width of the Wigner phase-space distribution is suggested, and the advantage over conventional OCT images is discussed. Because all previous published studies regarding the Wigner function are carried out in the transmission geometry, it is important to note that the extended Huygens-Fresnel principle and the ABCD matrix formalism may be used successfully to describe this geometry (within the paraxial approximation). Therefore for completeness we present in an appendix the general closed-form solution for the Wigner phase-space distribution function in ABCD paraxial optical systems for direct propagation through random media, and in a second appendix absorption effects are included.

  6. Microstructures and microtextures of natural cokes: A case study of heat-affected coking coals from the Jharia coalfield, India

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ashok K. [Central Fuel Research Institute, CSIR, Dhanbad-828108 (India); Singh, Mahendra P. [Department of Geology, Banaras Hindu University, Varanasi-221005 (India); Sharma, Mamta; Srivastava, Sunil K.

    2007-07-02

    In Jharia coalfield, nearly 1250 Mt of coking coal has been devolatilized due to igneous intrusives and {proportional_to} 1900 Mt due to mine fires. This paper is an effort to investigate the effect of carbonization in two intrusive affected coal seams of Ena (seam XIII) and Alkusa (seam XIV) collieries of this coalfield. Through petrographic studies by microscopy, characterization of normal and heat-affected coals was carried out. The microstructures and microtextures produced due to extraneous heat have been related to nature and extent of heat, location of heating source, and quality and quantity of natural coke produced. Based on the results of this study and earlier studies, an effort has been made to study the classification scheme for microtextures of natural cokes generated through in-situ carbonization of the coal seams. It has been observed that in case of such heat effects under overburden pressure, the anisotropy is much more pronounced as compared to laboratory-carbonized cokes. In the mildly carbonized coals (pre-plastic phase, < 300 C) the vitrinite attained higher reflectance than normal vitrinite, liptinite started disappearing, and inertinite remained unaffected. In the moderately affected coals (plastic phase, 300-500 C), mesophase spheres and fused natural cokes were generated from the reactives (vitrinite and liptinite maceral groups), the liptinites disappeared, and structurally, the inertinites remained almost unchanged with slight increase in the reflectance value. In the severely heat-affected coals (post plastic phase, > 500 C) the identified microtextures were mesophase spheres, different shapes and sizes of natural cokes, graphitic sphaeroliths, pyrolytic carbons, inerts with morpho-structural changes and slightly higher reflectance values, and altered and unaltered mineral matters. A gradual change in the heat-affected coals with increasing temperature was observed with respect to location of intrusive body. It has been concluded that

  7. Critical thinking evaluation in reflective writing: Development and testing of Carter Assessment of Critical Thinking in Midwifery (Reflection).

    Science.gov (United States)

    Carter, Amanda G; Creedy, Debra K; Sidebotham, Mary

    2017-11-01

    develop and test a tool designed for use by academics to evaluate pre-registration midwifery students' critical thinking skills in reflective writing. a descriptive cohort design was used. a random sample (n = 100) of archived student reflective writings based on a clinical event or experience during 2014 and 2015. a staged model for tool development was used to develop a fifteen item scale involving item generation; mapping of draft items to critical thinking concepts and expert review to test content validity; inter-rater reliability testing; pilot testing of the tool on 100 reflective writings; and psychometric testing. Item scores were analysed for mean, range and standard deviation. Internal reliability, content and construct validity were assessed. expert review of the tool revealed a high content validity index score of 0.98. Using two independent raters to establish inter-rater reliability, good absolute agreement of 72% was achieved with a Kappa coefficient K = 0.43 (pcritical thinking in reflective writing. Validation with large diverse samples is warranted. reflective practice is a key learning and teaching strategy in undergraduate Bachelor of Midwifery programmes and essential for safe, competent practice. There is the potential to enhance critical thinking development by assessingreflective writing with the CACTiM (reflection) tool to provide formative and summative feedback to students and inform teaching strategies. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  8. Combined effects of petrographic and technological parameters on strength of porous coke substance

    Energy Technology Data Exchange (ETDEWEB)

    Dinel' t, V.M.; Shkoller, M.B.; Stankevich, A.S.; Korchuganova, G.S.

    1983-09-01

    The proportion of coke in modern blast furnaces has been reduced and at the same time ore burdens have increased. The coke itself now derives from a much wider range of coals. Laboratory tests related to the structural strength of cokes were carried out with charges composed of 14 representative coals. Results showed that vitrinite reflectance and bulk density were the critical parameters, followed by petrographic composition. Increasing bulk density of the charge from 0.6 to 0.9 g/cm/sup 3/ produces coke with a structural strength which counteracts the effects of increasing diversity in both petrography and reflectance in any one charge.

  9. Reflectance variability of surface coatings reveals characteristic eigenvalue spectra

    Science.gov (United States)

    Medina, José M.; Díaz, José A.; Barros, Rui

    2012-10-01

    We have examined the trial-to-trial variability of the reflectance spectra of surface coatings containing effect pigments. Principal component analysis of reflectances was done at each detection angle separately. A method for classification of principal components is applied based on the eigenvalue spectra. It was found that the eigenvalue spectra follow characteristic power laws and depend on the detection angle. Three different subsets of principal components were examined to separate the relevant spectral features related to the pigments from other noise sources. Reconstruction of the reflectance spectra by taking only the first subset indicated that reflectance variability was higher at near-specular reflection, suggesting a correlation with the trial-to-trial deposition of effect pigments. Reconstruction by using the second subset indicates that variability was higher at short wavelengths. Finally, reconstruction by using only the third subset indicates that reflectance variability was not totally random as a function of the wavelength. The methods employed can be useful in the evaluation of color variability in industrial paint application processes.

  10. Hydrocarbons prospecting using an integrated approach of petrography, geochemistry and modeling of organic matter transformation. Analysis and reconstitution of the thermal history of the central carboniferous basins of Asturias (Spain) and of the Sabinas - Piedras Negras basin (Coahuila, Mexico); Prospection des hydrocarbures par une approche integree de petrographie, geochimie et modelisation de la transformation de la matiere organique. Analyse et reconstitution de l'histoire thermique des Bassins Carbonifere Central des Asturies (Espagne) et Sabinas - Piedras Negras (Coahuila, Mexique)

    Energy Technology Data Exchange (ETDEWEB)

    Piedad-Sanchez, N.

    2004-09-01

    Solid knowledge of the transformation and evolution of organic matter during hydrocarbon generation in sedimentary basins serves to improve natural gas exploration. With this geological problem in mind, the thermal influence on organic matter was analyzed in two basins containing different characteristics (age, composition of organic matter, litho-stratigraphy, depth, thickness of the layers of rock, the maturation of organic matter, etc.) in order to understand the natural processes in generating oil and natural gas. With a view to studying this geological phenomenon, this work outlines the study of the chemical and macerals composition, the coal rank and geochemical characteristics of organic matter in these two sedimentary basins for the first time: The Asturian Central Carboniferous Basin (Spain) and Sabinas - Piedras Negras Basin (Mexico). Moreover, an approach to shed light on the thermal history and evolution of organic matter through 1D modeling in the two basins is developed. The Central Carboniferous Basin in Asturias is an important coal mining area where coal types range from bituminous carbons with high content in volatile matter to anthracite. The petrographical and geochemical study in this region has shown that at the moment of oil and gas exploration, the coals correspond to an efficient expulsion of oil and have been formed in an environment of swamp with a facies rich in vitrinite, low in sulfur and ash and varying in mineral content. As regards the paleo-environmental reconstruction, the bio-markers suggest a swamp with a relatively high water table and a humid climate. The coal type, the vitrinite reflectance and the volatile matter content in the basin show a N-S trend which could be correlated to the paleo-temperatures calculated in this study. These data point to the influence of two thermal gradients in the region: A normal thermal gradient of long duration and an oblique thermal gradient of short duration due to a pluton. The evolution of

  11. Neutron Transport in Finite Random Media with Pure-Triplet Scattering

    International Nuclear Information System (INIS)

    Sallaha, M.; Hendi, A.A.

    2008-01-01

    The solution of the one-speed neutron transport equation in a finite slab random medium with pure-triplet anisotropic scattering is studied. The stochastic medium is assumed to consist of two randomly mixed immiscible fluids. The cross section and the scattering kernel are treated as discrete random variables, which obey the same statistics as Markovian processes and exponential chord length statistics. The medium boundaries are considered to have specular reflectivities with angular-dependent externally incident flux. The deterministic solution is obtained by using Pomraning-Eddington approximation. Numerical results are calculated for the average reflectivity and average transmissivity for different values of the single scattering albedo and varying the parameters which characterize the random medium. Compared to the results obtained by Adams et al. in case of isotropic scattering that based on the Monte Carlo technique, it can be seen that we have good comparable data

  12. Characteristics of the Triassic Source Rocks of the Aitutu Formation in the (West Timor Basin

    Directory of Open Access Journals (Sweden)

    Asep Kurnia Permana

    2014-12-01

    Full Text Available DOI:10.17014/ijog.v1i3.192The Triassic rocks of the (West Timor Basin have been identified that was mainly deposited in the  marine environment. The fine grained clastics and carbonate  rocks of this Triassic marine  facies are considered to be the most promising source rocks potential in this basin. In this paper we present geochemical and petrographic data from outcrop samples of the Triassic carbonate Aitutu Formation, due to emphasized the organic maturation, kerogen type of the organic matter and the origin of the organic matter.  A representative of selected sample were subjected to the Rock-Eval Pyrolisis, vitrinite reflectance and thermal alteration index, bitumen extraction, were analyzed on the GC-MS. The samples were collected from marine deposit of the Triassic Sequence. The TOC values of the analyzed sample range between rich and rich organic richness (0.51% - 9.16%, wt.%, TOC, which consists mainly of type II and III kerogen and the organic matter consider to be predominantly oil/gas prone and gas prone potential. The thermal maturity assessed from Tmax, TAI, and vitrinite reflectance shows an immature to early peak mature stage of the organic matter. The GC-MS analyses of the biomarkers indicate mainly the organic matter derived from mixed source rocks facies containing alga debris and higher plant terrestrial origin.

  13. Pyrolysis-gas chromatographic method for kerogen typing

    Energy Technology Data Exchange (ETDEWEB)

    Larter, S.R.; Douglas, A.G.

    1980-01-01

    The classification of kerogens according to their type and rank is important for the definition of any kerogen assemblage. Whereas optical methods of rank determination are well known, vitrinite reflectance and spore coloration being the most widely accepted chemical methods for typing kerogens are less developed. In this work we show that pyrograms, produced by pyrolyzing microgram quantities of solvent-extracted kerogens, enable not only their characterization in terms of a chromatographic fingerprint but also the production of a numerical type index determined as the ratio of m(+p)-xylene/n-octene (oct-1-ene) in the pyrogram. This index appears to be a close function of kerogen type. Type 3 kerogens (Tissot et al., 1974), including vitrinite, provide a high type index and have pyrolysates dominated by aromatic and phenolic compounds whereas type 1 kerogens provide an aliphatic-rich pyrolysate and consequently a low type index. The type index described here correlates well with microscopic and elemental analysis data and the pyrogram fingerprint provides an additional level of characterization not attainable with other current typing techniques.

  14. Reflecting reflection in supervision

    DEFF Research Database (Denmark)

    Lystbæk, Christian Tang

    associated with reflection and an exploration of alternative conceptions that view reflection within the context of settings which have a more group- and team-based orientation. Drawing on an action research project on health care supervision, the paper questions whether we should reject earlier views...... of reflection, rehabilitate them in order to capture broader connotations or move to new ways of regarding reflection that are more in keeping with not only reflective but also emotive, normative and formative views on supervision. The paper presents a critical perspective on supervision that challenge...... the current reflective paradigm I supervision and relate this to emotive, normative and formative views supervision. The paper is relevant for Nordic educational research into the supervision and guidance...

  15. Thermal maturity and organic composition of Pennsylvanian coals and carbonaceous shales, north-central Texas: Implications for coalbed gas potential

    Energy Technology Data Exchange (ETDEWEB)

    Hackley, Paul C. [U.S. Geological Survey, 956 National Center, Reston, VA 20192 (United States); Guevara, Edgar H.; Hentz, Tucker F. [Bureau of Economic Geology, The University of Texas at Austin, Austin, TX 78713 (United States); Hook, Robert W. [1301 Constant Springs Drive, Austin, TX 78746 (United States)

    2009-01-31

    Thermal maturity was determined for about 120 core, cuttings, and outcrop samples to investigate the potential for coalbed gas resources in Pennsylvanian strata of north-central Texas. Shallow (< 600 m; 2000 ft) coal and carbonaceous shale cuttings samples from the Middle-Upper Pennsylvanian Strawn, Canyon, and Cisco Groups in Archer and Young Counties on the Eastern Shelf of the Midland basin (northwest and downdip from the outcrop) yielded mean random vitrinite reflectance (R{sub o}) values between about 0.4 and 0.8%. This range of R{sub o} values indicates rank from subbituminous C to high volatile A bituminous in the shallow subsurface, which may be sufficient for early thermogenic gas generation. Near-surface (< 100 m; 300 ft) core and outcrop samples of coal from areas of historical underground coal mining in the region yielded similar R{sub o} values of 0.5 to 0.8%. Carbonaceous shale core samples of Lower Pennsylvanian strata (lower Atoka Group) from two deeper wells (samples from {proportional_to} 1650 m; 5400 ft) in Jack and western Wise Counties in the western part of the Fort Worth basin yielded higher R{sub o} values of about 1.0%. Pyrolysis and petrographic data for the lower Atoka samples indicate mixed Type II/Type III organic matter, suggesting generated hydrocarbons may be both gas- and oil-prone. In all other samples, organic material is dominated by Type III organic matter (vitrinite), indicating that generated hydrocarbons should be gas-prone. Individual coal beds are thin at outcrop (< 1 m; 3.3 ft), laterally discontinuous, and moderately high in ash yield and sulfur content. A possible analog for coalbed gas potential in the Pennsylvanian section of north-central Texas occurs on the northeast Oklahoma shelf and in the Cherokee basin of southeastern Kansas, where contemporaneous gas-producing coal beds are similar in thickness, quality, and rank. (author)

  16. Evaluating the gas content of coals and isolated maceral concentrates from the Paleocene Guasare Coalfield, Venezuela

    International Nuclear Information System (INIS)

    Berbesi, L.A.; Marquez, G.; Martinez, M.; Requena, A.

    2009-01-01

    This work presents the results from evaluating the gases sorbed by coal samples extracted from the Paleocene Guasare Coalfield (Marcelina Formation, northwestern Venezuela), as well as by their distinct maceral concentrates. The aim of this work has been to obtain an initial experimental main value of the gas content per unit weight of high volatile bituminous A coal samples from the open-pit Paso Diablo mine. An additional goal was to study differences in the CH 4 storage ability of the distinct maceral groups forming part of the coal matrix. Both the coal samples and the maceral concentrates were studied by thermogravimetric analysis (TGA) in order to determine the temperature to be used in subsequent experiments. On-line analyses of hydrocarbons (C 1 , C 2 , C 3 ) and CO 2 yielded gas concentrations, plus δ 13 C values. Thermogenic gas is prevalent in the Guasare coals with vitrinite reflectance (%R o ) values from 0.65% to 0.88%. The amount of gas retained in the coals and maceral concentrates was measured with a special device that allows determination of the volume of gas sorbed by a solid sample subjected to controlled thermal treatment. The average coalbed gas concentration obtained was 0.51 cm 3 /g. The following list of maceral concentrates shows the relative capacity for the volume of sorbed gas per unit weight: inertinite > low-density vitrinite > liptinite ∼ high-density vitrinite. It is concluded that the gas volumes retained in the distinct maceral concentrates are not controlled by porosity but rather by their microscopic morphology.

  17. Palynologic and petrographic intervals in the upper Pennsylvanian McLeansboro Group, Western Kentucky

    Energy Technology Data Exchange (ETDEWEB)

    Hower, J.C.; Helfrich, C.T.; Williams, D.A. (University of Kentucky, Lexington, KY (United States). Center for Applied Energy Research)

    1994-07-01

    The McLeansboro Group in the Western Kentucky coal field spans the upper Desmoinesian (Westphalian D) and the Missourian and Virgilian series (Stephanian). Significant features of the McLeansboro Group are the marine zones over most of the coals and paleochannels, which are the only disruptions to the continuity of other lithologies. Patoka Formation (lower Missourian) coals are dominated by tree fern spores with lesser amounts of sphenopsids, ferns and cordaites spores. Only the No. 15 coal bed exceeds 80% vitrinite: the vitrinite content of the No. 16 coal bed is less than 72%. The Bond formation (upper Missourian) represents a distinct floristic interval, with a greater diversity of plant groups than in the Patoka Formation. The coals generally exceed 80% vitrinite. The Mattoon Formation (Virgillian) coals have a variety of palynomorph assemblages. The low-sulfur Geiger Lake coal bed is dominated by tree fern spores, with important contributions from other ferns and sphenopsids. Similar to the underlying tree fern interval vitrinite contents are less than 80%. The uppermost Mattoon coals are dominated by tree ferns and are notable in being the only coals more than 1 m thick in Stephanian portion of the section, with the top coal being 4.3 m thick. The uppermost coals generally contain more than 80% vitrinite. The palynologic/petrographic intervals appear to represent fluctuating dry (low vitrinite) and wet intervals within the Stephanian, which was itself drier than the Westphalian D. 21 refs., 4 figs., 2 tabs.

  18. Optical performance of random anti-reflection structured surfaces (rARSS) on spherical lenses

    Science.gov (United States)

    Taylor, Courtney D.

    Random anti-reflection structured surfaces (rARSS) have been reported to improve transmittance of optical-grade fused silica planar substrates to values greater than 99%. These textures are fabricated directly on the substrates using reactive-ion/inductively-coupled plasma etching (RIE/ICP) techniques, and often result in transmitted spectra with no measurable interference effects (fringes) for a wide range of wavelengths. The RIE/ICP processes used in the fabrication process to etch the rARSS is anisotropic and thus well suited for planar components. The improvement in spectral transmission has been found to be independent of optical incidence angles for values from 0° to +/-30°. Qualifying and quantifying the rARSS performance on curved substrates, such as convex lenses, is required to optimize the fabrication of the desired AR effect on optical-power elements. In this work, rARSS was fabricated on fused silica plano-convex (PCX) and plano-concave (PCV) lenses using a planar-substrate optimized RIE process to maximize optical transmission in the range from 500 to 1100 nm. An additional set of lenses were etched in a non-optimized ICP process to provide additional comparisons. Results are presented from optical transmission and beam propagation tests (optimized lenses only) of rARSS lenses for both TE and TM incident polarizations at a wavelength of 633 nm and over a 70° full field of view in both singlet and doublet configurations. These results suggest optimization of the fabrication process is not required, mainly due to the wide angle-of-incidence AR tolerance performance of the rARSS lenses. Non-optimized recipe lenses showed low transmission enhancement, and confirmed the need to optimized etch recipes prior to process transfer of PCX/PCV lenses. Beam propagation tests indicated no major beam degradation through the optimized lens elements. Scanning electron microscopy (SEM) images confirmed different structure between optimized and non-optimized samples

  19. See, reflect, learn more: qualitative analysis of breaking bad news reflective narratives.

    Science.gov (United States)

    Karnieli-Miller, Orit; Palombo, Michal; Meitar, Dafna

    2018-05-01

    Breaking bad news (BBN) is a challenge that requires multiple professional competencies. BBN teaching often includes didactic and group role-playing sessions. Both are useful and important, but exclude another critical component of students' learning: day-to-day role-model observation in the clinics. Given the importance of observation and the potential benefit of reflective writing in teaching, we have incorporated reflective writing into our BBN course. The aim of this study was to enhance our understanding of the learning potential in reflective writing about BBN encounters and the ability to identify components that inhibit this learning. This was a systematic qualitative immersion/crystallization analysis of 166 randomly selected BBN narratives written by 83 senior medical students. We analysed the narratives in an iterative consensus-building process to identify the issues discussed, the lessons learned and the enhanced understanding of BBN. Having previously been unaware of, not invited to or having avoided BBN encounters, the mandatory assignment led students to search for or ask their mentors to join them in BBN encounters. Observation and reflective writing enhanced students' awareness that 'bad news' is relative and subjective, while shedding light on patients', families', physicians' and their own experiences and needs, revealing the importance of the different components of the BBN protocol. We identified diversity among the narratives and the extent of students' learning. Narrative writing provided students with an opportunity for a deliberative learning process. This led to deeper understanding of BBN encounters, of how to apply the newly taught protocol, or of the need for it. This process connected the formal and informal or hidden curricula. To maximise learning through reflective writing, students should be encouraged to write in detail about a recent observed encounter, analyse it according to the protocol, address different participants

  20. Nanoscale silver-assisted wet etching of crystalline silicon for anti-reflection surface textures.

    Science.gov (United States)

    Li, Rui; Wang, Shuling; Chuwongin, Santhad; Zhou, Weidong

    2013-01-01

    We report here an electro-less metal-assisted chemical etching (MacEtch) process as light management surface-texturing technique for single crystalline Si photovoltaics. Random Silver nanostructures were formed on top of the Si surface based on the thin film evaporation and annealing process. Significant reflection reduction was obtained from the fabricated Si sample, with approximately 2% reflection over a wide spectra range (300 to 1050 nm). The work demonstrates the potential of MacEtch process for anti-reflection surface texture fabrication of large area, high efficiency, and low cost thin film solar cell.

  1. Security authentication using the reflective glass pattern imaging effect.

    Science.gov (United States)

    Zhu, Ji Cheng; Shen, Su; Wu, Jian Hong

    2015-11-01

    The reflective glass pattern imaging effect is investigated experimentally for the utility in forming a synthetic 3D image as a security authentication device in this Letter. An array of homogeneously randomly distributed reflective elements and a corresponding micropattern array are integrated onto a thin layer of polyester film aiming to create a vivid image floating over a substrate surface, which can be clearly visible to the naked eye. By using the reflective-type configuration, the micro-optic system can be realized on a thinner substrate and is immune to external stain due to its flat working plane. A novel gravure-like doctor blading technique can realize a resolution up to 12,000 dpi and a stringent 2D alignment requirement should be imposed. Such devices can find applications in document security and banknotes or other valuable items to protect them against forgery.

  2. Brain potentials index executive functions during random number generation.

    Science.gov (United States)

    Joppich, Gregor; Däuper, Jan; Dengler, Reinhard; Johannes, Sönke; Rodriguez-Fornells, Antoni; Münte, Thomas F

    2004-06-01

    The generation of random sequences is considered to tax different executive functions. To explore the involvement of these functions further, brain potentials were recorded in 16 healthy young adults while either engaging in random number generation (RNG) by pressing the number keys on a computer keyboard in a random sequence or in ordered number generation (ONG) necessitating key presses in the canonical order. Key presses were paced by an external auditory stimulus to yield either fast (1 press/800 ms) or slow (1 press/1300 ms) sequences in separate runs. Attentional demands of random and ordered tasks were assessed by the introduction of a secondary task (key-press to a target tone). The P3 amplitude to the target tone of this secondary task was reduced during RNG, reflecting the greater consumption of attentional resources during RNG. Moreover, RNG led to a left frontal negativity peaking 140 ms after the onset of the pacing stimulus, whenever the subjects produced a true random response. This negativity could be attributed to the left dorsolateral prefrontal cortex and was absent when numbers were repeated. This negativity was interpreted as an index for the inhibition of habitual responses. Finally, in response locked ERPs a negative component was apparent peaking about 50 ms after the key-press that was more prominent during RNG. Source localization suggested a medial frontal source. This effect was tentatively interpreted as a reflection of the greater monitoring demands during random sequence generation.

  3. The Reflective Learning Continuum: Reflecting on Reflection

    Science.gov (United States)

    Peltier, James W.; Hay, Amanda; Drago, William

    2005-01-01

    The importance of reflection to marketing educators is increasingly recognized. However, there is a lack of empirical research that considers reflection within the context of both the marketing and general business education literature. This article describes the use of an instrument that can be used to measure four identified levels of a…

  4. Maturation-related changes in the distribution of ester-bound fatty acids and alcohols in a coal series from the New Zealand Coal Band covering diagenetic to catagenetic coalification levels

    DEFF Research Database (Denmark)

    Glombitza, Clemens; Mangelsdorf, Kai; Horsfield, Brian

    2009-01-01

    A rank series of lignites and coals of low to moderate maturation levels (vitrinite reflectance (R0): 0.27–0.8%) from the New Zealand Coal Band were investigated using alkaline ester cleavage experiments to reveal compositional changes of ester bound components (fatty acids and alcohols) during...... increase during early catagenesis before decreasing again during main catagenesis. This intermittent increase was related to the short chain fatty acids. To obtain a maturity related signal and to eliminate facies related scattering in the amounts of fatty acids in the coal samples, the carbon preference...

  5. Coke properties in relation to charge preparation techniques. [Selective crushing

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, O S

    1979-01-01

    Selective crushing is essential to obtain the required coke properties, so that in the coarse fractions there is a considerable reduction in the middlings and dirt normally difficult to crush. These are at the same time enriched with vitrinite so that there is an increase in the coal substance as such, reflected in improved caking capacity in the coarse size range. Various methods of selective crushing are employed, including air entrainment mills, fluidised bed systems. Other advantages claimed for selective crushing are the uniform pore distribution and air permeability and also the diminished breakage stress.

  6. Dependence of coke properties on the method of charge preparation

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, O S

    1979-04-01

    Selective crushing is essential to obtain the required coke properties, so that in the coarse fractions there is a considerable reduction in the middlings and dirt normally difficult to crush. These are at the same time enriched with vitrinite so that there is an increase in the coal substance as such, reflected in improved caking capacity in the coarse size range. Various methods of selective crushing are employed, including air entrainment mills, fluidised bed systems. Other advantages claimed for selective crushing are the uniform pore distribution and air permeability and also the diminished breakage stress.

  7. A preliminary investigation into the suitability of South African anthracites for Soderberg electrodes

    International Nuclear Information System (INIS)

    Krynauw, J.R.

    1983-01-01

    As part of an investigation into ways of improving the quality of Soderberg electrodes made in South Africa, a mineralogical, geochemical and petrographical examination was made of some South African anthracites in comparison with anthracites from North Vietnam and Germany. The results of X-ray diffraction on raw and calcined anthracites and the analyses of the macerals in raw anthracites indicated that the sample from North Vietnam, which is an anthracite that is used in Japan for Soderberg-electrode paste, has a very high vitrinite content, low sulphur and phoshorus contents, and, when it has been calcined, contains more graphite than the other samples examined. The samples from the South African collieries, Balgray and Brockwell, contain more sulphur and phosphorus, and much less vitrinite, than the North Vietnamese samples. The anthracite from Natal Anthracite Colliery Ltd contains sulphur and phosphorus in amounts similar to those of the North Vietnamese anthracite, but it has a low vitrinite content. All three South African anthracites contain similar, low amounts of graphite when they have been calcined. The German anthracite, when calcined, contains intermediate amounts of vitrinite and graphite. Chemical analyses of the ash showed that there are major differences in the composition of the ash and the mineralogy of the various anthracites. The results of this preliminary investigation indicate that the most important requisite for graphitisation is a high vitrinite content

  8. Analyses and characterization of fossil carbonaceous materials for silicon production

    Energy Technology Data Exchange (ETDEWEB)

    Myrvaagnes, Viktor

    2008-01-15

    Production of high silicon alloys is carried out in submerged arc furnaces by reduction of silicon bearing oxides (typically quartz) with carbon materials. Carbonaceous materials like coal, coke, charcoal and woodchips are commonly used as reduction materials in the process. Primarily based on historical prices of charcoal compared to fossil reduction materials, the Norwegian Ferroalloy Industry has mostly been using coal and coke (char) as the source of carbon. From a process point of view, the most important role of the carbonaceous material is to react with SiO gas to produce SiC. The ability of the reduction materials to react with SiO gas can be measured and the value is recognized as the reactivity of the carbon source. Reactivity is one of the most important parameters in the smelting process and is commonly acknowledged to strongly affect both productivity and specific energy consumption. The main objectives of this work has been to establish methods to characterize the material properties of fossil carbonaceous reduction materials used in the silicon process and to evaluated how these properties affect the reactivity towards SiO gas. In order to accomplish these objectives, three run of mine (ROM) single seam coals which are particularly well suited for ferroalloy production were selected. Two Carboniferous coals from USA (Blue Gem) and Poland (Staszic) with similar rank, but significantly different composition as well as a Permian coal from Australia (Peak Downs) have been characterized by chemical- and petrographical methods. Blue Gem is a homogeneous coal, low in mineral inclusions and macerals of the inertinite group and determined to have a random vitrinite reflectance of 0.71 %. Staszic has a similar reflectance of vitrinite (0.72 %), but is determined to be a very inhomogeneous coal with both inertinite macerals and minerals embedded in the vitrinite matrix. Peak Downs has a random reflectance of vitrinite of 1.32 % and is hence the coal sample of

  9. Study on the Light Scattering from Random Rough Surfaces by Kirrhoff Approximation

    Directory of Open Access Journals (Sweden)

    Keding Yan

    2014-07-01

    Full Text Available In order to study the space distribution characteristics of light scattering from random rough surfaces, the linear filtering method is used to generate a series of Gaussian randomly rough surfaces, and the Kirchhoff Approximation is used to calculate the scattered light intensity distribution from random metal and dielectric rough surfaces. The three characteristics of the scattered light intensity distribution peak, the intensity distribution width and the position of peak are reviewed. Numerical calculation results show that significant differences between scattering characteristics of metal surfaces and the dielectric surfaces exist. The light scattering characteristics are jointly influenced by the slope distribution and reflectance of surface element. The scattered light intensity distribution is affected by common influence of surface local slope distribution and surface local reflectivity. The results can provide a basis theory for the research to lidar target surface scattering characteristics.

  10. Eo-Oligocene Oil Shales of the Talawi, Lubuktaruk, and Kiliranjao Areas, West Sumatra: Are they potential source rocks?

    Directory of Open Access Journals (Sweden)

    M. Iqbal

    2014-12-01

    Full Text Available DOI:10.17014/ijog.v1i3.198To anticipate the increasing energy demand, additional data and information covering unconventional fossil fuels such as oil shale must be acquired to promote the usage of alternative energy sources to crude oil. The Talawi and Lubuktaruk regions situated within intra-montane Ombilin Basin, and the Kiliranjao assumed to be a small intra montane basin are occupied by Eo-Oligocene sediments of Sangkarewang and Kiliran Formations, respectively. Field activity, geochemical screening techniques, and organic petrographic analysis, supported by SEM mode, are methods used. Most of the oil shale sequence is typically of an organically rich-succession comprising predominantly well-bedded, laminated and fissile, brownish to dark grey organic-rich shale and mudstone rocks. The exinite macerals within oil shale comprise mainly Pediastrum-lamalginite with minor cutinite, resinite, liptodetrinite, sporinite, bituminite, and rare Botryococcus-telalginite. Therefore; the oil shale deposits can be described as “lamosites”. Minor vitrinite maceral is also recognized. TOC analysis on selected shale samples corresponds to a fair up to excellent category of source rock characterization. The hydrogen index (HI for all samples shows a range of values from 207 - 864, and pyrolysis yield (PY ranges from 2.67 to 79.72 mg HC/g rock. The kerogen is suggested to be of mixed Type II and Type I autochthonous materials such as alginite, with minor allochthonous substances. Oil samples collected appear to be positioned within more oil prone rather than gas prone. Thermal maturity of the oil shales gained from Tmax value and production index (PI tends to show immature to marginally/early mature stage. A consistency in the thermal maturity level results by using both Tmax and vitrinite reflectance value is recognized. On the basis of  SEM analysis, the oil shale has undergone a late eodiagenetic process. Thereby, overall, vitrinite reflectance

  11. Challenging Narcissus, or Reflecting on Reflecting.

    Science.gov (United States)

    Achilles, C. M.

    The concept of reflective practice and teaching people to be reflective practitioners is examined. The document begins with a look at professional knowledge according to three prominent professionals in the educational administration field: Schon, Schein, and Achilles. "Reflective" strategies that could be incorporated into courses and…

  12. Reflectance distribution in optimal transmittance cavities: The remains of a higher dimensional space

    International Nuclear Information System (INIS)

    Naumis, Gerardo G.; Bazan, A.; Torres, M.; Aragon, J.L.; Quintero-Torres, R.

    2008-01-01

    One of the few examples in which the physical properties of an incommensurable system reflect an underlying higher dimensionality is presented. Specifically, we show that the reflectivity distribution of an incommensurable one-dimensional cavity is given by the density of states of a tight-binding Hamiltonian in a two-dimensional triangular lattice. Such effect is due to an independent phase decoupling of the scattered waves, produced by the incommensurable nature of the system, which mimics a random noise generator. This principle can be applied to design a cavity that avoids resonant reflections for almost any incident wave. An optical analogy, by using three mirrors with incommensurable distances between them, is also presented. Such array produces a countable infinite fractal set of reflections, a phenomena which is opposite to the effect of optical invisibility

  13. Late Cretaceous coal overlying karstic bauxite deposits in the Parnassus-Ghiona Unit, Central Greece: Coal characteristics and depositional environment

    Energy Technology Data Exchange (ETDEWEB)

    Kalaitzidis, Stavros; Siavalas, George; Christanis, Kimon [Dept. of Geology, University of Patras, 26504 Rio-Patras (Greece); Skarpelis, Nikos [Dept. of Geology and Geoenvironment, University of Athens, 15784 Zografou (Greece); Araujo, Carla Viviane [Petrobras-Cenpes GEOQ/PDEXP, Rua Horacio Macedo n 950, Cidade Universitaria - Ilha do Fundao, 21941-915 Rio de Janeiro (Brazil)

    2010-04-01

    The Pera-Lakkos coal located on top of bauxite deposits in the Ghiona mining district (Central Greece), is the only known Mesozoic (Late Cretaceous) coal in the country. It was derived from herbaceous plants and algae growing in mildly brackish mires that formed behind a barrier system during a regression of the sea, on a karstified limestone partly filled in with bauxitic detritus. Petrological, mineralogical and geochemical data point to the predominance of reducing conditions and intense organic matter degradation in the palaeomires. O/C vs. H/C and OI vs. HI plots, based on elemental analysis and Rock-Eval data, characterize kerogen types I/II. This reflects the relatively high liptinite content of the coal. Besides kerogen composition, O/C vs. H/C plot for the Pera-Lakkos coals is in accordance with a catagenesis stage of maturation in contrast with vitrinite reflectance and T{sub max} from Rock-Eval pyrolysis, which indicate the onset of oil window maturation stage. Suppression of vitrinite reflectance should be considered and the high liptinite content corroborates this hypothesis. Despite some favourable aspects for petroleum generation presented by the Pera-Lakkos coal, its maximum thickness (up to 50 cm) points to a restricted potential for petroleum generation. Coal oxidation took place either during the late stage of peat formation, due to wave action accompanying the subsequent marine transgression, or epigenetically after the emergence of the whole sequence due to percolation of drainage waters. Both options are also supported by the REE shale-normalized profiles, which demonstrate an upwards depletion in the coal layer. Oxidation also affected pyrite included in the coal; this led to the formation of acidic (sulfate-rich) solutions, which percolated downwards resulting in bleaching of the upper part of the underlying bauxite. (author)

  14. Time-dependent reflection at the localization transition

    Science.gov (United States)

    Skipetrov, Sergey E.; Sinha, Aritra

    2018-03-01

    A short quasimonochromatic wave packet incident on a semi-infinite disordered medium gives rise to a reflected wave. The intensity of the latter decays as a power law, 1 /tα , in the long-time limit. Using the one-dimensional Aubry-André model, we show that in the vicinity of the critical point of Anderson localization transition, the decay slows down, and the power-law exponent α becomes smaller than both α =2 found in the Anderson localization regime and α =3 /2 expected for a one-dimensional random walk of classical particles.

  15. Asthma Self-Management Model: Randomized Controlled Trial

    Science.gov (United States)

    Olivera, Carolina M. X.; Vianna, Elcio Oliveira; Bonizio, Roni C.; de Menezes, Marcelo B.; Ferraz, Erica; Cetlin, Andrea A.; Valdevite, Laura M.; Almeida, Gustavo A.; Araujo, Ana S.; Simoneti, Christian S.; de Freitas, Amanda; Lizzi, Elisangela A.; Borges, Marcos C.; de Freitas, Osvaldo

    2016-01-01

    Information for patients provided by the pharmacist is reflected in adhesion to treatment, clinical results and patient quality of life. The objective of this study was to assess an asthma self-management model for rational medicine use. This was a randomized controlled trial with 60 asthmatic patients assigned to attend five modules presented by…

  16. Cultural differences in emotion regulation during self-reflection on negative personal experiences.

    Science.gov (United States)

    Tsai, William; Lau, Anna S

    2013-01-01

    Reflecting on negative personal experiences has implications for mood that may vary as a function of specific domains (e.g., achievement vs. interpersonal) and cultural orientation (e.g., interdependence vs. independence). This study investigated cultural differences in the social-cognitive and affective processes undertaken as Easterners and Westerners reflected on negative interpersonal and performance experiences. One hundred Asian Americans and 92 European-American college students were randomly assigned to one of three conditions: interpersonal rejection, achievement failure, or a control condition. Results revealed that Asian Americans experienced greater distress than European Americans after self-reflecting over a failed interpersonal experience, suggesting cultural sensitivity in the relational domain. Consistent with theoretical predictions, analysis of the social cognitive and affective processes that participants engaged in during self-reflection provided some evidence that self-enhancement may buffer distress for European Americans, while emotion suppression may be adaptive for Asian Americans.

  17. Compression-cuticle relationship of seed ferns: Insights from liquid-solid states FTIR (Late Palaeozoic-Early Mesozoic, Canada-Spain-Argentina)

    Science.gov (United States)

    Zodrow, E.L.; D'Angelo, J. A.; Mastalerz, Maria; Keefe, D.

    2009-01-01

    Cuticles have been macerated from suitably preserved compressed fossil foliage by Schulze's process for the past 150 years, whereas the physical-biochemical relationship between the "coalified layer" with preserved cuticle as a unit has hardly been investigated, although they provide complementary information. This relationship is conceptualized by an analogue model of the anatomy of an extant leaf: "vitrinite (mesophyll) + cuticle (biomacropolymer) = compression". Alkaline solutions from Schulze's process as a proxy for the vitrinite, are studied by means of liquid-solid states Fourier transform infrared spectroscopy (FTIR). In addition, cuticle-free coalified layers and fossilized cuticles of seed ferns mainly from Canada, Spain and Argentina of Late Pennsylvanian-Late Triassic age are included in the study sample. Infrared data of cuticle and alkaline solutions differ which is primarily contingent on the mesophyll +biomacropolymer characteristics. The compression records two pathways of organic matter transformation. One is the vitrinized component that reflects the diagenetic-post-diagenetic coalification history parallel with the evolution of the associated coal seam. The other is the cuticle that reflects the sum-total of evolutionary pathway of the biomacropolymer, its monomeric, or polymeric fragmentation, though factors promoting preservation include entombing clay minerals and lower pH conditions. Caution is advised when interpreting liquid-state-based FTIR data, as some IR signals may have resulted from the interaction of Schulze's process with the cuticular biochemistry. A biochemical-study course for taphonomy is suggested, as fossilized cuticles, cuticle-free coalified layers, and compressions are responses to shared physicogeochemical factors. ?? 2009 Elsevier B.V. All rights reserved.

  18. Compression-cuticle relationship of seed ferns: Insights from liquid-solid states FTIR (Late Palaeozoic-Early Mesozoic, Canada-Spain-Argentina)

    Energy Technology Data Exchange (ETDEWEB)

    Zodrow, Erwin L. [Palaeobotanical Laboratory, Cape Breton University, Sydney, Nova Scotia (Canada); D' Angelo, Jose A. [Instituto Argentino de Nivologia, Glaciologia y Ciencias Ambientales (IANIGLA), CCT-CONICET-Mendoza, Avda. Ruiz Leal s/n Parque Gral. San Martin (5500) Mendoza (Argentina); Area de Quimica, Instituto de Ciencias Basicas, Universidad Nacional de Cuyo, Centro Universitario - M5502JMA - Mendoza (Argentina); Mastalerz, Maria [Indiana Geological Survey, Indiana University, 611 North Walnut Grove, Bloomington, IN 47405-2208 (United States); Keefe, Dale [Molecular Spectroscopy Research Laboratory, Department of Chemistry, Cape Breton University, Sydney, Nova Scotia (Canada)

    2009-08-01

    Cuticles have been macerated from suitably preserved compressed fossil foliage by Schulze's process for the past 150 years, whereas the physical-biochemical relationship between the ''coalified layer'' with preserved cuticle as a unit has hardly been investigated, although they provide complementary information. This relationship is conceptualized by an analogue model of the anatomy of an extant leaf: ''vitrinite (mesophyll) + cuticle (biomacropolymer) = compression''. Alkaline solutions from Schulze's process as a proxy for the vitrinite, are studied by means of liquid-solid states Fourier transform infrared spectroscopy (FTIR). In addition, cuticle-free coalified layers and fossilized cuticles of seed ferns mainly from Canada, Spain and Argentina of Late Pennsylvanian-Late Triassic age are included in the study sample. Infrared data of cuticle and alkaline solutions differ which is primarily contingent on the mesophyll +biomacropolymer characteristics. The compression records two pathways of organic matter transformation. One is the vitrinized component that reflects the diagenetic-post-diagenetic coalification history parallel with the evolution of the associated coal seam. The other is the cuticle that reflects the sum-total of evolutionary pathway of the biomacropolymer, its monomeric, or polymeric fragmentation, though factors promoting preservation include entombing clay minerals and lower pH conditions. Caution is advised when interpreting liquid-state-based FTIR data, as some IR signals may have resulted from the interaction of Schulze's process with the cuticular biochemistry. A biochemical-study course for taphonomy is suggested, as fossilized cuticles, cuticle-free coalified layers, and compressions are responses to shared physicogeochemical factors. (author)

  19. Flexible manipulation of terahertz wave reflection using polarization insensitive coding metasurfaces.

    Science.gov (United States)

    Jiu-Sheng, Li; Ze-Jiang, Zhao; Jian-Quan, Yao

    2017-11-27

    In order to extend to 3-bit encoding, we propose notched-wheel structures as polarization insensitive coding metasurfaces to control terahertz wave reflection and suppress backward scattering. By using a coding sequence of "00110011…" along x-axis direction and 16 × 16 random coding sequence, we investigate the polarization insensitive properties of the coding metasurfaces. By designing the coding sequences of the basic coding elements, the terahertz wave reflection can be flexibly manipulated. Additionally, radar cross section (RCS) reduction in the backward direction is less than -10dB in a wide band. The present approach can offer application for novel terahertz manipulation devices.

  20. The coalification profile of the Grambach 1 exploration well - first indication of an oil kitchen in the molasse basin; Das Inkohlungsprofil der Bohrung Grambach 1 - erster Hinweis auf eine ``Oelkueche`` im Molassebecken

    Energy Technology Data Exchange (ETDEWEB)

    Hiltmann, W.; Wehner, H. [Bundesanstalt fuer Geowissenschaften und Rohstoffe, Hannover (Germany); Kuckelkorn, K. [Niedersaechsisches Landesamt fuer Bodenforschung, Hannover (Germany)

    1999-06-01

    For the first time an exploration well beneath the German part of the Alpine overthrust zone met vitrinite reflectance values raising up to 1,6% R{sub r} - and this in a widespread tectonic high position. The interpretation as an oil and gas kitchen is confirmed by oil maturity (derived by biomarkers and carbon isotope ratios). (orig.) [Deutsch] Erstmals traf im deutschen Teil der alpinen Ueberschiebungszone eine Bohrung ein bis 1,6% R{sub r} ansteigendes Inkohlungsprofil an und dies in einer ausgedehnten Hochscholle. Die Interpretation als `Oel- und Gaskueche` wurde durch die Reife des zugeschlossenen Erdoels (Biomarker, Kohlenstoffisotopen) bestaetigt. (orig.)

  1. Seismic reflection imaging, accounting for primary and multiple reflections

    Science.gov (United States)

    Wapenaar, Kees; van der Neut, Joost; Thorbecke, Jan; Broggini, Filippo; Slob, Evert; Snieder, Roel

    2015-04-01

    Imaging of seismic reflection data is usually based on the assumption that the seismic response consists of primary reflections only. Multiple reflections, i.e. waves that have reflected more than once, are treated as primaries and are imaged at wrong positions. There are two classes of multiple reflections, which we will call surface-related multiples and internal multiples. Surface-related multiples are those multiples that contain at least one reflection at the earth's surface, whereas internal multiples consist of waves that have reflected only at subsurface interfaces. Surface-related multiples are the strongest, but also relatively easy to deal with because the reflecting boundary (the earth's surface) is known. Internal multiples constitute a much more difficult problem for seismic imaging, because the positions and properties of the reflecting interfaces are not known. We are developing reflection imaging methodology which deals with internal multiples. Starting with the Marchenko equation for 1D inverse scattering problems, we derived 3D Marchenko-type equations, which relate reflection data at the surface to Green's functions between virtual sources anywhere in the subsurface and receivers at the surface. Based on these equations, we derived an iterative scheme by which these Green's functions can be retrieved from the reflection data at the surface. This iterative scheme requires an estimate of the direct wave of the Green's functions in a background medium. Note that this is precisely the same information that is also required by standard reflection imaging schemes. However, unlike in standard imaging, our iterative Marchenko scheme retrieves the multiple reflections of the Green's functions from the reflection data at the surface. For this, no knowledge of the positions and properties of the reflecting interfaces is required. Once the full Green's functions are retrieved, reflection imaging can be carried out by which the primaries and multiples are

  2. Polarization phenomena on coherent particle backscattering by random media

    International Nuclear Information System (INIS)

    Gorodnichev, E.E.; Dudarev, S.L.; Rogozkin, D.B.

    1990-01-01

    An exact solution is found for the problem of coherent enhanced backscattering of spin 1/2 particles by random media with small-radius scatterers. The polarization features in the angular spectrum are analyzed for particles reflected by three- and two-dimensional disordered systems and by medium with Anderson disorder (periodic system of random scatterers). The analysis is carried out in the case of magnetic and spin-orbit interaction with the scattering centers. The effects predicted have not any analogues on coherent backscattering of light and scalar waves

  3. Relation between the petrographic composition of coal and the morphology of pyrolysis char produced in fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    B. Valentim; M.J. Lemos de Sousa; P. Abelha; D. Boavida; I. Gulyurtlu [Centro de Geologia da Universidade do Porto, Porto (Portugal)

    2004-06-01

    Several previous studies have already established, for pulverized coal combustion conditions, global correlations between petrographic composition of the coal and those of char produced from the same coal. However, for fluidized bed combustion, there has not been much new work since the eighties. The results presented in this paper include the petrographic characterization of seven different coals from several origins and also of their respective chars produced at 700, 800, 900, and 1000{sup o}C in a laboratory fluidized bed reactor. The results show a marked predominance of tenuispheres as the trial temperatures increase. While vitrinite-rich coals essentially produced highly porous chars, the inertinite-rich coals produced large amounts of medium- and low-porous chars. Semi-anthracite vitrinite produced high-porous chars and thermal affected coal particles originated low-porous and angular char morphotypes. The analysis of the data obtained revealed that vitrinite + liptinite related well with the high-porous char (sum of cenospheres and tenuinetworks), classified as Group 1. The same trend, but with a weaker relation, was also observed between vitrinite and liptinite rich microlithotypes and Group 1. 32 refs., 17 refs., 3 tabs.

  4. Pure-Triplet Scattering for Radiative Transfer in Semi-infinite Random Media with Refractive-Index Dependent Boundary

    International Nuclear Information System (INIS)

    Sallah, M.; Degheidy, A.R.

    2013-01-01

    Radiative transfer problem for pure-triplet scattering, in participating half-space random medium is proposed. The medium is assumed to be random with binary Markovian mixtures (e.g. radiation transfer in astrophysical contexts where the clouds and clear sky play and two-phase medium) described by Markovian statistics. The specular reflectivity of the boundary is angular-dependent described by the Fresnel's reflection probability function. The problem is solved at first in the deterministic case, and then the solution is averaged using the formalism developed by Levermore and Pomraning, to treat particles transport problems in statistical mixtures. Some physical quantities of interest such as the reflectivity of the boundary, average radiant energy, and average net flux are computed for various values of refractive index of the boundary

  5. Reflection and Non-Reflection of Particle Wavepackets

    Science.gov (United States)

    Cox, Timothy; Lekner, John

    2008-01-01

    Exact closed-form solutions of the time-dependent Schrodinger equation are obtained, describing the propagation of wavepackets in the neighbourhood of a potential. Examples given include zero reflection, total reflection and partial reflection of the wavepacket, for the sech[superscript 2]x/a, 1/x[superscript 2] and delta(x) potentials,…

  6. Effect of reflective practice education on self-reflection, insight, and reflective thinking among experienced nurses: a pilot study.

    Science.gov (United States)

    Asselin, Marilyn E; Fain, James A

    2013-01-01

    A mixed-method study was conducted to determine whether nurses' participation in a reflective practice continuing education program using a structured reflection model makes a difference in nurses' self-reflection, insight, and reflective thinking about clinical practice situations. Findings suggested that use of structured reflection using question cues, written narratives, and peer-facilitated reflection increased nurses' engagement in self-reflection and enhanced reflective thinking in practice. Including reflective practice education in novice orientation and preceptor training may be beneficial.

  7. Multi-parameter sensor based on random fiber lasers

    Directory of Open Access Journals (Sweden)

    Yanping Xu

    2016-09-01

    Full Text Available We demonstrate a concept of utilizing random fiber lasers to achieve multi-parameter sensing. The proposed random fiber ring laser consists of an erbium-doped fiber as the gain medium and a random fiber grating as the feedback. The random feedback is effectively realized by a large number of reflections from around 50000 femtosecond laser induced refractive index modulation regions over a 10cm standard single mode fiber. Numerous polarization-dependent spectral filters are formed and superimposed to provide multiple lasing lines with high signal-to-noise ratio up to 40dB, which gives an access for a high-fidelity multi-parameter sensing scheme. The number of sensing parameters can be controlled by the number of the lasing lines via input polarizations and wavelength shifts of each peak can be explored for the simultaneous multi-parameter sensing with one sensing probe. In addition, the random grating induced coupling between core and cladding modes can be potentially used for liquid medical sample sensing in medical diagnostics, biology and remote sensing in hostile environments.

  8. Calculating the bidirectional reflectance of natural vegetation covers using Boolean models and geometric optics

    Science.gov (United States)

    Strahler, Alan H.; Li, Xiao-Wen; Jupp, David L. B.

    1991-01-01

    The bidirectional radiance or reflectance of a forest or woodland can be modeled using principles of geometric optics and Boolean models for random sets in a three dimensional space. This model may be defined at two levels, the scene includes four components; sunlight and shadowed canopy, and sunlit and shadowed background. The reflectance of the scene is modeled as the sum of the reflectances of the individual components as weighted by their areal proportions in the field of view. At the leaf level, the canopy envelope is an assemblage of leaves, and thus the reflectance is a function of the areal proportions of sunlit and shadowed leaf, and sunlit and shadowed background. Because the proportions of scene components are dependent upon the directions of irradiance and exitance, the model accounts for the hotspot that is well known in leaf and tree canopies.

  9. Preliminary investigation of predictors of the cutting forces for some South African coals

    Energy Technology Data Exchange (ETDEWEB)

    MacGregor, I M; Baker, D R

    1985-08-01

    This paper discusses the possible use of petrological data and proximate analyses in the prediction of cutting forces for coal. It is restricted to the development of univariate predictors based on data from thirteen collieries in five major Transvaal and Orange Free State coalfields and three coal provinces. The aim of the work was the identification and development of the best predictors of mean peak cutting force and Hardgrove grindability index from among the independent variables evaluated. The data were processed according to the SPSS computer package. The analysis revealed reasonable correlations between the Hardgrove grindability index and (1) the volatiles and vitrinite content in the Vereeniging-Sasolburg and South Rand Coalfields, (2) the contents of vitrinite, vitrinite plus exinite, and minerals plus inertinite in the Eastern Transvaal Coalfield.

  10. Being a reflective teacher——reflection on group management

    Institute of Scientific and Technical Information of China (English)

    Pan; Lehui

    2015-01-01

    <正>Introduction According to Pollard and Triggs(1997),reflective teaching is a process through which the capacity to make such professional judgments can be developed and maintained.Then what is a reflective teacher?Reflective teacher is someone who reflects systematically on her practice in a constant attempt to improve

  11. Reliability of reflectance measures in passive filters

    Science.gov (United States)

    Saldiva de André, Carmen Diva; Afonso de André, Paulo; Rocha, Francisco Marcelo; Saldiva, Paulo Hilário Nascimento; Carvalho de Oliveira, Regiani; Singer, Julio M.

    2014-08-01

    Measurements of optical reflectance in passive filters impregnated with a reactive chemical solution may be transformed to ozone concentrations via a calibration curve and constitute a low cost alternative for environmental monitoring, mainly to estimate human exposure. Given the possibility of errors caused by exposure bias, it is common to consider sets of m filters exposed during a certain period to estimate the latent reflectance on n different sample occasions at a certain location. Mixed models with sample occasions as random effects are useful to analyze data obtained under such setups. The intra-class correlation coefficient of the mean of the m measurements is an indicator of the reliability of the latent reflectance estimates. Our objective is to determine m in order to obtain a pre-specified reliability of the estimates, taking possible outliers into account. To illustrate the procedure, we consider an experiment conducted at the Laboratory of Experimental Air Pollution, University of São Paulo, Brazil (LPAE/FMUSP), where sets of m = 3 filters were exposed during 7 days on n = 9 different occasions at a certain location. The results show that the reliability of the latent reflectance estimates for each occasion obtained under homoskedasticity is km = 0.74. A residual analysis suggests that the within-occasion variance for two of the occasions should be different from the others. A refined model with two within-occasion variance components was considered, yielding km = 0.56 for these occasions and km = 0.87 for the remaining ones. To guarantee that all estimates have a reliability of at least 80% we require measurements on m = 10 filters on each occasion.

  12. STRENGTHENING THE REFLECTIVE FUNCTIONING CAPACITIES OF PARENTS WHO HAVE A CHILD WITH A NEURODEVELOPMENTAL DISABILITY THROUGH A BRIEF, RELATIONSHIP-FOCUSED INTERVENTION.

    Science.gov (United States)

    Sealy, Julie; Glovinsky, Ira P

    2016-01-01

    This randomized controlled trial examined the reflective functioning capacities of caregivers who have a child with a neurodevelopmental disorder between the ages of 2 years 0 months and 6 years 11 months. Children with a neurodevelopmental disorder receive a range of diagnoses, including sutism; however, they all exhibit social communication challenges that can derail social relationships. Forty parent-child dyads in Barbados were randomly assigned to either a developmental individual-difference, relationship-based/floortime(DIR/FT) group (n = 20), or a psychoeducational (wait-list) group (n = 20) with parental reflective functioning measured before and after a 12-week DIR/FT treatment intervention. Results revealed significant gains in parental reflective functioning in the treatment group, as compared to the psychoeducational (wait-list) group, after the 12-week relationship-focused intervention. © 2016 Michigan Association for Infant Mental Health.

  13. An investigation into the impact of reflective teaching on EFL learners autonomy and intrinsic motivation

    Directory of Open Access Journals (Sweden)

    Elahe Fallah

    2015-12-01

    Full Text Available This study has sought to explore the effect of reflective teaching on learner autonomy and the intrinsic motivation of Iranian upper-intermediate female learners. The subjects included 60 adult upper-intermediate EFL learners chosen out of ninety, based on the scores obtained through administration of the TOEFL exam. They were randomly assigned to two groups: a the experimental group - taught by a reflective teacher - and b the control group instructed by an unreflective teacher. The motivation questionnaire and the autonomy questionnaire were administered to both groups to make sure that the two groups were not significantly different in terms of the level of motivation and autonomy. The experimental group was then taught by the reflective teacher and the control group was taught by the unreflective teacher who adopted no tangible reflective actions. Finally, both groups sat for motivation and autonomy questionnaires. The results indicate that reflective teaching leads to the enhancement of both learners’ autonomy and the intrinsic motivation level.

  14. Petrography and geochemistry of Oligocene bituminous coal from the Jiu Valley, Petrosani basin (southern Carpathian Mountains), Romania

    Energy Technology Data Exchange (ETDEWEB)

    Belkin, Harvey E.; Tewalt, Susan J. [U.S. Geological Survey, 956 National Center, Reston, VA 20192 (United States); Hower, James C. [University of Kentucky Center for Applied Energy Research, 2540 Research Park Drive, Lexington, KY 40511 (United States); Stucker, J.D. [University of Kentucky Center for Applied Energy Research, 2540 Research Park Drive, Lexington, KY 40511 (United States); University of Kentucky Department of Earth and Environmental Sciences, Lexington, KY 40506 (United States); O' Keefe, Jennifer M.K. [Morehead State University, Morehead, KY, 40351 (United States); Tatu, Calin A. [University of Medicine and Pharmacy, Department of Immunology, Clinical Laboratory No. 1, Pta. E. Murgu No. 2, RO-1900 Timisoara (Romania); Buia, Grigore [University of Petrosani, Department of Geology, University St. 20, RO-2675 Petrosani (Romania)

    2010-05-01

    Belt samples of Oligocene (Chattian) bituminous coal from 10 underground mines located in the Jiu Valley, Hunedoara County, Petrosani basin, Romania, have been examined and analyzed for proximate and ultimate analysis, major-, minor- and trace-element chemistry, organic petrography, and vitrinite reflectance. The mineral chemistry and mode of occurrence of trace elements also have been investigated using SEM and electron microprobe techniques. Twenty coal beds occur in the Jiu Valley and most of the samples are from bed no. 3, the most productive bed of the Dilja-Uricani Formation of Oligocene age. The Petrosani basin, oriented SW-NE, is 48-km long, 10-km wide at the eastern part and 2-km wide at the western part. The coal mines are distributed along the center of the valley generally following the Jiu de Vest River. Reflectance measurements indicate that the rank of the coals ranges from high-volatile B to high-volatile A bituminous. Overall, rank decreases from the southwest to the northeast. In bed no. 3, R{sub max} varies from 0.75% in the northeast to 0.93% in the southwest. Although, most Oligocene coals in Romania and adjacent countries are lignite in rank, the Jiu Valley bituminous coals have been affected by regional metamorphism and attending hydrothermal fluids related to the Alpine orogenic event. The coals are all dominated by vitrinite; resinite and funginite are important minor macerals in most of the coals. Pyrite and carbonate generally dominate the mineral assemblages with carbonate more abundant in the northwest. Siderite occurs as nodules and masses within the macerals (generally vitrinite). Dolomite and calcite occur as fracture fillings, plant-cell fillings, and in other authigenic forms. Late-stage fracture fillings are siderite, dolomite, calcite, and ankerite. In one instance, two populations of siderite ({proportional_to} 35 and {proportional_to} 45 wt.% FeO) plus ankerite fill a large fracture. Late-stage pyrite framboid alteration is Ni

  15. Improving Pulse Rate Measurements during Random Motion Using a Wearable Multichannel Reflectance Photoplethysmograph

    Directory of Open Access Journals (Sweden)

    Kristen M. Warren

    2016-03-01

    Full Text Available Photoplethysmographic (PPG waveforms are used to acquire pulse rate (PR measurements from pulsatile arterial blood volume. PPG waveforms are highly susceptible to motion artifacts (MA, limiting the implementation of PR measurements in mobile physiological monitoring devices. Previous studies have shown that multichannel photoplethysmograms can successfully acquire diverse signal information during simple, repetitive motion, leading to differences in motion tolerance across channels. In this paper, we investigate the performance of a custom-built multichannel forehead-mounted photoplethysmographic sensor under a variety of intense motion artifacts. We introduce an advanced multichannel template-matching algorithm that chooses the channel with the least motion artifact to calculate PR for each time instant. We show that for a wide variety of random motion, channels respond differently to motion artifacts, and the multichannel estimate outperforms single-channel estimates in terms of motion tolerance, signal quality, and PR errors. We have acquired 31 data sets consisting of PPG waveforms corrupted by random motion and show that the accuracy of PR measurements achieved was increased by up to 2.7 bpm when the multichannel-switching algorithm was compared to individual channels. The percentage of PR measurements with error ≤ 5 bpm during motion increased by 18.9% when the multichannel switching algorithm was compared to the mean PR from all channels. Moreover, our algorithm enables automatic selection of the best signal fidelity channel at each time point among the multichannel PPG data.

  16. Reflective photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Lentine, Anthony L.; Nielson, Gregory N.; Cruz-Campa, Jose Luis; Okandan, Murat; Goeke, Ronald S.

    2018-03-06

    A photovoltaic module includes colorized reflective photovoltaic cells that act as pixels. The colorized reflective photovoltaic cells are arranged so that reflections from the photovoltaic cells or pixels visually combine into an image on the photovoltaic module. The colorized photovoltaic cell or pixel is composed of a set of 100 to 256 base color sub-pixel reflective segments or sub-pixels. The color of each pixel is determined by the combination of base color sub-pixels forming the pixel. As a result, each pixel can have a wide variety of colors using a set of base colors, which are created, from sub-pixel reflective segments having standard film thicknesses.

  17. Zeolite facies and regional rank of bituminous coals

    Energy Technology Data Exchange (ETDEWEB)

    Kisch, H J

    1966-01-01

    The author has correlated diagnostic analcime-, heulandite-, and laumontite-bearing mineral assemblages from four areas in the Upper Carboniferous and the Permian of New South Wales with the rank of the associated coals, represented by the carbon content of vitrinite. The results show that lowest-grade regional metamorphism of the zeolite facies reflects at least in part the same physical conditions of metamorphism as the increase in degree of coalification (rank) in the bituminous coal range. Degree of coalification is probably independent of partial pressures of H/sub 2/O and CO/sub 2/: it is controlled mainly by maximum depth of burial, its duration, and the geothermal gradient.

  18. Coal rank, distribution, and coalbed methane potential of the Lower Cretaceous Luscar Group, Bow River to Blackstone River, central Alberta foothills

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, F M; Kalkreuth, W D

    1994-12-31

    Mapping data on Lower Cretaceous Luscar Group coals in the central Alberta foothills is presented. The coals outcrop in the Inner Foothills from the Bow River to the boundary between Alberta and British Columbia, north of Grande Cache. Both subsurface and surface mapping data is presented. The coal rank is highly variable and depends on sample location and depth, as established by vitrinite reflectance studies on trench samples and cuttings gathered from petroleum exploration wells. The conventional coal resource potential and the coalbed methane potential for the area are discussed with reference to the map sheets provided. 29 refs., 45 figs., 3 tabs., 3 apps.

  19. Broadband diffuse terahertz wave scattering by flexible metasurface with randomized phase distribution.

    Science.gov (United States)

    Zhang, Yin; Liang, Lanju; Yang, Jing; Feng, Yijun; Zhu, Bo; Zhao, Junming; Jiang, Tian; Jin, Biaobing; Liu, Weiwei

    2016-05-26

    Suppressing specular electromagnetic wave reflection or backward radar cross section is important and of broad interests in practical electromagnetic engineering. Here, we present a scheme to achieve broadband backward scattering reduction through diffuse terahertz wave reflection by a flexible metasurface. The diffuse scattering of terahertz wave is caused by the randomized reflection phase distribution on the metasurface, which consists of meta-particles of differently sized metallic patches arranged on top of a grounded polyimide substrate simply through a certain computer generated pseudorandom sequence. Both numerical simulations and experimental results demonstrate the ultralow specular reflection over a broad frequency band and wide angle of incidence due to the re-distribution of the incident energy into various directions. The diffuse scattering property is also polarization insensitive and can be well preserved when the flexible metasurface is conformably wrapped on a curved reflective object. The proposed design opens up a new route for specular reflection suppression, and may be applicable in stealth and other technology in the terahertz spectrum.

  20. Radiation Transport in Random Media With Large Fluctuations

    Science.gov (United States)

    Olson, Aaron; Prinja, Anil; Franke, Brian

    2017-09-01

    Neutral particle transport in media exhibiting large and complex material property spatial variation is modeled by representing cross sections as lognormal random functions of space and generated through a nonlinear memory-less transformation of a Gaussian process with covariance uniquely determined by the covariance of the cross section. A Karhunen-Loève decomposition of the Gaussian process is implemented to effciently generate realizations of the random cross sections and Woodcock Monte Carlo used to transport particles on each realization and generate benchmark solutions for the mean and variance of the particle flux as well as probability densities of the particle reflectance and transmittance. A computationally effcient stochastic collocation method is implemented to directly compute the statistical moments such as the mean and variance, while a polynomial chaos expansion in conjunction with stochastic collocation provides a convenient surrogate model that also produces probability densities of output quantities of interest. Extensive numerical testing demonstrates that use of stochastic reduced-order modeling provides an accurate and cost-effective alternative to random sampling for particle transport in random media.

  1. Propagation of a Strong Shock Over a Random Bed of Spherical Particles

    Energy Technology Data Exchange (ETDEWEB)

    Mehta, Y. [Univ. of Florida, Gainesville, FL (United States); Neal, C. [Univ. of Florida, Gainesville, FL (United States); Salari, K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jackson, T. L. [Univ. of Florida, Gainesville, FL (United States); Balachandar, S. [Univ. of Florida, Gainesville, FL (United States); Thakur, S. [Univ. of Florida, Gainesville, FL (United States)

    2017-04-11

    Propagation of a strong shock through a bed of particles results in complex wave dynamics such as a reflected shock, a transmitted shock, and highly unsteady flow inside the particle bed. In this paper we present three-dimensional numerical simulations of shock propagation in air over a random bed of particles. We assume the flow is inviscid and governed by the Euler equations of gas dynamics. Simulations are carried out by varying the volume fraction of the particle bed at a fixed shock Mach number. We compute the unsteady inviscid streamwise and transverse drag coefficients as a function of time for each particle in the random bed as a function of volume fraction. We show that (i) there are significant variations in the peak drag for the particles in the bed, (ii) the mean peak drag as a function of streamwise distance through the bed decreases with a slope that increases as the volume fraction increases, and (iii) the deviation from the mean peak drag does not correlate with local volume fraction. We also present the local Mach number and pressure contours for the different volume fractions to explain the various observed complex physical mechanisms occurring during the shock-particle interactions. Since the shock interaction with the random bed of particles leads to transmitted and reflected waves, we compute the average flow properties to characterize the strength of the transmitted and reflected shock waves and quantify the energy dissipation inside the particle bed. Finally, to better understand the complex wave dynamics in a random bed, we consider a simpler approximation of a planar shock propagating in a duct with a sudden area change. We obtain Riemann solutions to this problem, which are used to compare with fully resolved numerical simulations.

  2. Quantifying Reflection

    DEFF Research Database (Denmark)

    Alcock, Gordon Lindsay

    2013-01-01

    ´ These are all based on Blooms taxonomy and levels of competence and form a major part of individual student and group learning portfolios. Key Words :Project-Based learning, Reflective Portfolios, Self assessment, Defining learning gains, Developing learning strategies , Reflections on and for learning....... It contrasts the students’ self-assessment in a range of ‘product’ skills such as Revit, Structural Design, Mathematics of construction, Technical Installations; as well as ‘process’ competencies such as ‘Working in a team’, Sharing knowledge, Maintaining a portfolio and Reflecting ON learning and FOR learning......This paper documents 1st semester student reflections on “learning to learn” in a team-based PBL environment with quantitative and qualitative student reflective feedback on the learning gains of 60 Architectural Technology and Construction Management students at VIA University College, Denmark...

  3. Temperature-reflection I

    DEFF Research Database (Denmark)

    McGady, David A.

    2017-01-01

    -temperature path integrals for quantum field theories (QFTs) should be T-reflection invariant. Because multi-particle partition functions are equal to Euclidean path integrals for QFTs, we expect them to be T-reflection invariant. Single-particle partition functions though are often not invariant under T......In this paper, we revisit the claim that many partition functions are invariant under reflecting temperatures to negative values (T-reflection). The goal of this paper is to demarcate which partition functions should be invariant under T-reflection, and why. Our main claim is that finite...... that T-reflection is unrelated to time-reversal. Finally, we study the interplay between T-reflection and perturbation theory in the anharmonic harmonic oscillator in quantum mechanics and in Yang-Mills in four-dimensions. This is the first in a series of papers on temperature-reflections....

  4. Report on the achievements in the Sunshine Project in fiscal 1986. Surveys on coal type selection (coal type survey); 1986 nendo tanshu sentei chosa seika hokokusho. Tanshu chosa

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1987-03-01

    The purpose of the present study is to elucidate coal quality features of different types of coals and identify the relationship between the coal quality features and the liquefaction characteristics by performing liquefaction characteristic evaluation tests. Based on the result therefrom, a method is established for coal field assessment that can estimate yield of liquefaction in coal fields and coal mines to serve for selection of coal types suitable for liquefaction. Coal quality feature surveys and liquefaction characteristics evaluation tests under the standard conditions have been completed on 48 coal types including Canadian, Australian and American coals. Elucidating the coal quality features of different coals can specify parameters for the coal quality features related to the liquefaction characteristics. Coal ranks elucidate the vitrinite reflectance, structure constituent factors the vitrinite content, composite factors the volatile matter content, quantity of heat generation, and number of H/C and O/C atoms. Investigating the relationship between the coal quality features and the liquefaction characteristics can provide fundamental data for primary screening of raw material coals for liquefaction. The result of the liquefaction characteristics evaluation test under the standard conditions can be the detailed comparative data relative to data derived from the simplified liquefaction characteristics test that is performed to estimate liquefaction yield of specific coal field and coal mine. (NEDO)

  5. Reflection effects in multimode fiber systems utilizing laser transmitters

    Science.gov (United States)

    Bates, Harry E.

    1991-11-01

    A number of optical communication lines are now in use at NASA-Kennedy for the transmission of voice, computer data, and video signals. Now, all of these channels use a single carrier wavelength centered near 1300 or 1550 nm. Engineering tests in the past have given indications of the growth of systematic and random noise in the RF spectrum of a fiber network as the number of connector pairs is increased. This noise seems to occur when a laser transmitter is used instead of a LED. It has been suggested that the noise is caused by back reflections created at connector fiber interfaces. Experiments were performed to explore the effect of reflection on the transmitting laser under conditions of reflective feedback. This effort included computer integration of some of the instrumentation in the fiber optic lab using the Lab View software recently acquired by the lab group. The main goal was to interface the Anritsu Optical and RF spectrum analyzers to the MacIntosh II computer so that laser spectra and network RF spectra could be simultaneously and rapidly acquired in a form convenient for analysis. Both single and multimode fiber is installed at Kennedy. Since most are multimode, this effort concentrated on multimode systems.

  6. Theory of reflection reflection and transmission of electromagnetic, particle and acoustic waves

    CERN Document Server

    Lekner, John

    2016-01-01

    This book deals with the reflection of electromagnetic and particle waves by interfaces. The interfaces can be sharp or diffuse. The topics of the book contain absorption, inverse problems, anisotropy, pulses and finite beams, rough surfaces, matrix methods, numerical methods,  reflection of particle waves and neutron reflection. Exact general results are presented, followed by long wave reflection, variational theory, reflection amplitude equations of the Riccati type, and reflection of short waves. The Second Edition of the Theory of Reflection is an updated and much enlarged revision of the 1987 monograph. There are new chapters on periodically stratified media, ellipsometry, chiral media, neutron reflection and reflection of acoustic waves. The chapter on anisotropy is much extended, with a complete treatment of the reflection and transmission properties of arbitrarily oriented uniaxial crystals. The book gives a systematic and unified treatment reflection and transmission of electromagnetic and particle...

  7. Cultivating Reflective Practitioners in Technology Preparation: Constructing TPACK through Reflection

    Directory of Open Access Journals (Sweden)

    Liangyue Lu

    2013-12-01

    Full Text Available Teaching is a complex profession, which is further complicated by the integration of technology into classrooms. Reflection can help teachers unpack the complexity in their practice. Reflection can be an effective instructional strategy in helping preservice teachers develop technological pedagogical content knowledge (TPACK, the complex and dynamic knowledge necessary for effective technology integration into instruction. In this study, reflective activities were integrated into a Learning By Design (LBD environment, which was created to help preservice teachers develop TPACK. This paper investigated the participants’ TPACK development and examined how reflection helped them construct TPACK. Through content analysis of the participants’ reflective journals, the researcher found that the preservice teachers developed initial TPACK awareness. However, their reflection in technology knowledge and the content aspects of TPACK were limited and superficial. Interviews with the participants showed reflection helped the preservice teachers remember what they learned by describing and elaborating on their in-class experiences, pushed them to think about how to apply what they learned in their future classrooms, and helped them become more reflective and open-minded about using technology in classrooms. Finally, the researcher discussed this study’s implications for teacher educators and researchers.

  8. P2 : A random effects model with covariates for directed graphs

    NARCIS (Netherlands)

    van Duijn, M.A.J.; Snijders, T.A.B.; Zijlstra, B.J.H.

    A random effects model is proposed for the analysis of binary dyadic data that represent a social network or directed graph, using nodal and/or dyadic attributes as covariates. The network structure is reflected by modeling the dependence between the relations to and from the same actor or node.

  9. Reflecting on reflection in interprofessional education: implications for theory and practice.

    Science.gov (United States)

    Clark, Phillip G

    2009-05-01

    Interprofessional education (IPE) involves learning, and learning requires reflection. Educators need to "reflect more on reflection" if they are to be effective teachers in ensuring the learning outcomes essential for teamwork and interprofessional practice (IPP), including incorporating both theory and practice into the development of educational interventions. First, this discussion surveys the IPE-relevant literature on reflection, and then defines and refines the multidimensional concept of reflection as it relates to IPE in developing and implementing teamwork learning programs and experiences. Second, specific methods to promote reflection are presented and explored, including self-assessments, journaling, and written papers. Actual samples from student journals and assignments provide examples of the impacts of using these methods on participant reflection and learning. Finally, implications for an expanded understanding and application of reflection for IPE will be discussed, and recommendations made for educational practice and research in this area.

  10. Tagclouds and Group Cognition: Effect of Tagging Support on Students' Reflective Learning in Team Blogs

    Science.gov (United States)

    Xie, Ying; Lin, Shu-Yuan

    2016-01-01

    We investigated the effects of supported tagging (a prompting mechanism for students to stop and think about their writing) for team blogging on undergraduate students' reflective learning and the relationship between tagclouds and group cognition. Thirty-nine students were randomly assigned to six groups and blogged for 5 weeks. Three groups were…

  11. Backscattered EM-wave manipulation using low cost 1-bit reflective surface at W-band

    Science.gov (United States)

    Taher Al-Nuaimi, Mustafa K.; Hong, Wei; He, Yejun

    2018-04-01

    The design of low cost 1-bit reflective (non-absorptive) surfaces for manipulation of backscattered EM-waves and radar cross section (RCS) reduction at W-band is presented in this article. The presented surface is designed based on the reflection phase cancellation principle. The unit cell used to compose the proposed surface has an obelus (division symbol of short wire and two disks above and below) like shape printed on a grounded dielectric material. Using this unit cell, surfaces that can efficiently manipulate the backscattered RCS pattern by using the proposed obelus-shaped unit cell (as ‘0’ element) and its mirrored unit cell (as ‘1’ element) in one surface with a 180°  ±  35° reflection phase difference between their reflection phases are designed. The proposed surfaces can generate various kinds of backscattered RCS patterns, such as single, three, or four lobes or even a low-level (reduced RCS) diffused reflection pattern when those two unit cells are distributed randomly across the surface aperture. For experimental characterization purposes, a 50  ×  50 mm2 surface is fabricated and measured.

  12. Frequency and temperature dependent mobility of a charged carrier and randomly interrupted strand

    International Nuclear Information System (INIS)

    Kumar, N.; Jayannavar, A.M.

    1981-05-01

    Randomly interrupted strand model of a one-dimensional conductor is considered. Exact analytical expression is obtained for the temperature dependent as mobility for a finite segment drawn at random, taking into account the reflecting barriers at the two open ends. The real part of mobility shows a broad resonance as a function of both frequency and tempeature, and vanishes quadratically in the dc limit. The frequency (temperature) maximum shifts to higher values for higher temperatures (frequencies). (author)

  13. Evaluation of BRDF Archetypes for Representing Surface Reflectance Anisotropy Using MODIS BRDF Data

    Directory of Open Access Journals (Sweden)

    Hu Zhang

    2015-06-01

    Full Text Available Bidirectional reflectance distribution function (BRDF archetypes extracted from the Moderate Resolution Imaging Spectroradiometer (MODIS BRDF/Albedo product over the global Earth Observing System Land Validation Core Sites can be used to simplify BRDF models. The present study attempts to evaluate the representativeness of BRDF archetypes for surface reflectance anisotropy. Five-year forward-modeled MODIS multi-angular reflectance (MCD-ref and aditional actual MODIS multi-angular observations (MCD-obs in four growing periods in 2008 over three tiles were taken as validation data. First, BRDF archetypes in the principal plane were qualitatively compared with the time-series MODIS BRDF product of randomly sampled pixels. Secondly, BRDF archetypes were used to fit MCD-ref, and the average root-mean-squared errors (RMSEs over each tile were examined for these five years. Finally, both BRDF archetypes and the MODIS BRDF were used to fit MCD-obs, and the histograms of the fit-RMSEs were compared. The consistency of the directional reflectance between the BRDF archetypes and MODIS BRDFs in nadir-view, hotspot and entire viewing hemisphere at 30° and 50° solar geometries were also examined. The results confirm that BRDF archetypes are representative of surface reflectance anisotropy for available snow-free MODIS data.

  14. Random Forest Application for NEXRAD Radar Data Quality Control

    Science.gov (United States)

    Keem, M.; Seo, B. C.; Krajewski, W. F.

    2017-12-01

    Identification and elimination of non-meteorological radar echoes (e.g., returns from ground, wind turbines, and biological targets) are the basic data quality control steps before radar data use in quantitative applications (e.g., precipitation estimation). Although WSR-88Ds' recent upgrade to dual-polarization has enhanced this quality control and echo classification, there are still challenges to detect some non-meteorological echoes that show precipitation-like characteristics (e.g., wind turbine or anomalous propagation clutter embedded in rain). With this in mind, a new quality control method using Random Forest is proposed in this study. This classification algorithm is known to produce reliable results with less uncertainty. The method introduces randomness into sampling and feature selections and integrates consequent multiple decision trees. The multidimensional structure of the trees can characterize the statistical interactions of involved multiple features in complex situations. The authors explore the performance of Random Forest method for NEXRAD radar data quality control. Training datasets are selected using several clear cases of precipitation and non-precipitation (but with some non-meteorological echoes). The model is structured using available candidate features (from the NEXRAD data) such as horizontal reflectivity, differential reflectivity, differential phase shift, copolar correlation coefficient, and their horizontal textures (e.g., local standard deviation). The influence of each feature on classification results are quantified by variable importance measures that are automatically estimated by the Random Forest algorithm. Therefore, the number and types of features in the final forest can be examined based on the classification accuracy. The authors demonstrate the capability of the proposed approach using several cases ranging from distinct to complex rain/no-rain events and compare the performance with the existing algorithms (e

  15. Chemical and nanometer-scale structure of kerogen and its change during thermal maturation investigated by advanced solid-state 13C NMR spectroscopy

    Science.gov (United States)

    Mao, J.; Fang, X.; Lan, Y.; Schimmelmann, A.; Mastalerz, Maria; Xu, L.; Schmidt-Rohr, K.

    2010-01-01

    We have used advanced and quantitative solid-state nuclear magnetic resonance (NMR) techniques to investigate structural changes in a series of type II kerogen samples from the New Albany Shale across a range of maturity (vitrinite reflectance R0 from 0.29% to 1.27%). Specific functional groups such as CH3, CH2, alkyl CH, aromatic CH, aromatic C-O, and other nonprotonated aromatics, as well as "oil prone" and "gas prone" carbons, have been quantified by 13C NMR; atomic H/C and O/C ratios calculated from the NMR data agree with elemental analysis. Relationships between NMR structural parameters and vitrinite reflectance, a proxy for thermal maturity, were evaluated. The aromatic cluster size is probed in terms of the fraction of aromatic carbons that are protonated (???30%) and the average distance of aromatic C from the nearest protons in long-range H-C dephasing, both of which do not increase much with maturation, in spite of a great increase in aromaticity. The aromatic clusters in the most mature sample consist of ???30 carbons, and of ???20 carbons in the least mature samples. Proof of many links between alkyl chains and aromatic rings is provided by short-range and long-range 1H-13C correlation NMR. The alkyl segments provide most H in the samples; even at a carbon aromaticity of 83%, the fraction of aromatic H is only 38%. While aromaticity increases with thermal maturity, most other NMR structural parameters, including the aromatic C-O fractions, decrease. Aromaticity is confirmed as an excellent NMR structural parameter for assessing thermal maturity. In this series of samples, thermal maturation mostly increases aromaticity by reducing the length of the alkyl chains attached to the aromatic cores, not by pronounced growth of the size of the fused aromatic ring clusters. ?? 2010 Elsevier Ltd. All rights reserved.

  16. Random resistor network model of minimal conductivity in graphene.

    Science.gov (United States)

    Cheianov, Vadim V; Fal'ko, Vladimir I; Altshuler, Boris L; Aleiner, Igor L

    2007-10-26

    Transport in undoped graphene is related to percolating current patterns in the networks of n- and p-type regions reflecting the strong bipolar charge density fluctuations. Finite transparency of the p-n junctions is vital in establishing the macroscopic conductivity. We propose a random resistor network model to analyze scaling dependencies of the conductance on the doping and disorder, the quantum magnetoresistance and the corresponding dephasing rate.

  17. Comparison of blogged and written reflections in two medicine clerkships.

    Science.gov (United States)

    Fischer, Melissa A; Haley, Heather-Lyn; Saarinen, Carrie L; Chretien, Katherine C

    2011-02-01

    academic medical centres may adopt new learning technologies with little data on their effectiveness or on how they compare with traditional methodologies. We conducted a comparative study of student reflective writings produced using either an electronic (blog) format or a traditional written (essay) format to assess differences in content, depth of reflection and student preference. students in internal medicine clerkships at two US medical schools during the 2008-2009 academic year were quasi-randomly assigned to one of two study arms according to which they were asked to either write a traditional reflective essay and subsequently join in faculty-moderated, small-group discussion (n = 45), or post two writings to a faculty-moderated group blog and provide at least one comment on a peer's posts (n = 50). Examples from a pilot block were used to refine coding methods and determine inter-rater reliability. Writings were coded for theme and level of reflection by two blinded authors; these coding processes reached inter-rater reliabilities of 91% and 80%, respectively. Anonymous pre- and post-clerkship surveys assessed student perceptions and preferences. student writing addressed seven main themes: (i) being humanistic; (ii) professional behaviour; (iii) understanding caregiving relationships; (iv) being a student; (v) clinical learning; (vi) dealing with death and dying, and (vii) the health care system, quality, safety and public health. The distribution of themes was similar across institutions and study arms. The level of reflection did not differ between study arms. Post-clerkship surveys showed that student preferences for blogging or essay writing were predicted by experience, with the majority favouring the method they had used. our study suggests there is no significant difference in themes addressed or levels of reflection achieved when students complete a similar assignment via online blogging or traditional essay writing. Given this, faculty staff

  18. Design of a flat-top fiber Bragg filter via quasi-random modulation of the refractive index.

    Science.gov (United States)

    Derevyanko, Stanislav

    2008-10-15

    The statistics of the reflection spectrum of a short-correlated disordered fiber Bragg grating are studied. The averaged spectrum appears to be flat inside the bandgap and has significantly suppressed sidelobes compared to the uniform grating of the same bandwidth. This is due to the Anderson localization of the modes of a disordered grating. This observation prompts a new algorithm for designing passband reflection gratings. Using the stochastic invariant imbedding approach it is possible to obtain the probability distribution function for the random reflection coefficient inside the bandgap and obtain both the variance of the averaged reflectivity as well as the distribution of the time delay of the grating.

  19. Media for Reflection

    DEFF Research Database (Denmark)

    Knudsen, Morten

    2016-01-01

    This article develops the concept media for reflection in the interest of conceptualizing the interpretative frames that enable and limit reflection in management and leadership education. The concept ‘media for reflection’ allows us to conceptualize the social and cultural mediation of reflection...... without reducing reflection to an effect of the social structures and cultural norms in which it is embedded. Based on the developed theoretical framework, this article analyses how a renaissance ‘mirror for princes’ and contemporary research-based management education mediate reflection. The content...... of the mediations is analysed as well as the societal and organizational background. Furthermore, the means by which the two media enable and limit reflection in different ways is compared. Finally, the article discusses possible implications of the analysis in terms of management and leadership education....

  20. The laser microprobe mass analyser for determining partitioning of minor and trace elements among intimately associated macerals: an example from the Swallow Wood coal bed, Yorkshire, UK

    Science.gov (United States)

    Lyons, P.C.; Morelli, J.J.; Hercules, D.M.; Lineman, D.; Thompson-Rizer, C. L.; Dulong, F.T.

    1990-01-01

    A study of the elemental composition of intimately associated coal macerals in the English Swallow Wood coal bed was conducted using a laser microprobe mass analyser, and indicated a similar trace and minor elemental chemistry in the vitrinite and cutinite and a different elemental signature in the fusinite. Three to six sites were analysed within each maceral during the study by laser micro mass spectrometry (LAMMS). Al, Ba, Ca, Cl, Cr, Dy, F, Fe, Ga, K, Li, Mg, Na, S, Si, Sr, Ti, V, and Y were detected by LAMMS in all three macerals but not necessarily at each site analysed. The signal intensities of major isotopic peaks were normalized to the signal intensity of the m z 85 peak (C7H) to determine the relative minor- and trace-element concentrations among the three dominant macerals. The vitrinite and the cutinite were depleted in Ba, Ca, Dy, Li, Mg, Sr, and Y relative to their concentrations observed in the fusinite. The cutinite was distinguished over vitrinite by less Ti, V, Cr and Ca, and K Ca $ ??1 (relative signal intensities). The fusinite, relative to the cutinite and vitrinite, was relatively depleted in Cr, Sc, Ti, and V. The fusinite, as compared with both the cutinite and vitrinite, was relatively enriched in Ba, Ca, Dy, Li, Mg, Sr, and Y, and also showed the most intense m z 64, 65, 66 signals (possibly S2+, HS2+, H2S2+, respectively). The LAMMS data indicate a common source for most elements and selective loss from the maceral precursors in the peat or entrapment of certain elements as mineral matter, most likely during the peat stage or during early diagenesis. The relatively high amounts of Ba, Ca, Dy, Li, Mg, Sr, and Y in the fusinite are consistent with micron and submicron mineral-matter inclusions such as carbonates and Ca-Al phosphates (probably crandallite group minerals). Mineralogical data on the whole coal, the LAMMS chemistry of the vitrinite and cutinite, and scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDAX) of

  1. Beyond the Margins: Reflective Writing and Development of Reflective Capacity in Medical Education

    Science.gov (United States)

    Reis, Shmuel P.

    2010-01-01

    Reflective capacity has been described as an essential characteristic of professionally competent clinical practice, core to ACGME competencies. Reflection has been recently linked to promoting effective use of feedback in medical education and associated with improved diagnostic accuracy, suggesting promising outcomes. There has been a proliferation of reflective writing pedagogy within medical education to foster development of reflective capacity, extend empathy with deepened understanding of patients’ experience of illness, and promote practitioner well-being. At Alpert Med, “interactive” reflective writing with guided individualized feedback from interdisciplinary faculty to students’ reflective writing has been implemented in a Doctoring course and Family Medicine clerkship as an educational method to achieve these aims. Such initiatives, however, raise fundamental questions of reflection definition, program design, efficacy of methods, and outcomes assessment. Within this article, we consider opportunities and challenges associated with implementation of reflective writing curricula for promotion of reflective capacity within medical education. We reflect upon reflection. PMID:20407840

  2. Geothermal studies in oil field districts of North China

    Science.gov (United States)

    Wang, Ji-An; Wang, Ji-Yang; Yan, Shu-Zhen; Lu, Xiu-Wen

    In North China, Tertiary sediments give the main oil-genetic series. The mean value of terrestrial heat flow density has been considered to be 60 - 65 mW/m2, and the geothermal gradient in Tertiary sediments usually ranges from 30 to 40° C/km in the region studied. Supposing that the onset of oil generation lies at about 90° C, the upper limit of the depth of oil-generation is at about 2000 to 2500 m depth. Recent paleogeothermal studies using vitrinite reflectance, clay and authigenic minerals, as well as other methods showed that in Eocene the geothermal gradient has been higher than at present. Some results were obtained and discussed.

  3. Geochemical evaluation of marginal basins in the south of Bahia state, Brazil

    International Nuclear Information System (INIS)

    Gaglianone, P.C.; Trindade, L.A.F.; Nascimento, M.M. do

    1987-01-01

    Geochemical analyses were performed on more than 700 rock samples and 4 oil samples, from Mucuri, Cumuruxatiba and Jequitinhonha basins, offshore Bahia state, Brazil. The methods employed in this study includes the evaluation of organic carbon contents, Rock-Eval pyrolysis, vitrinite reflectance, carbon isotopes, assessment of oils and extrats by liquid and gas chromatography and gas chromatography - spectrometry. Three main source rock systems have been identified in offshore Bahia: the Mucuri shales from Rio da Serra and Aratu Stages lower Neocomian related to a lacustrine fresh water environment; the Jiquia shales (Upper Neocomian) deposited in a lacustrine saline water environment, and the Alagoas Shales related to an evaporitic environment of Aptian age. (author) [pt

  4. Anti-reflection textured structures by wet etching and island lithography for surface-enhanced Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chao, Bo-Kai [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Cheng, Hsin-Hung [Department of Marine Engineering, Taipei College of Maritime Technology, Taipei 11174, Taiwan (China); Nien, Li-Wei; Chen, Miin-Jang [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Nagao, Tadaaki [Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Li, Jia-Han [Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Hsueh, Chun-Hway, E-mail: hsuehc@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2015-12-01

    Graphical abstract: - Highlights: • We fabricated textured SERS substrate with a high surface area and low reflectance. • Large surface area of substrate contains more gold nanodroplets to absorb analytes. • Low reflectance of textured SERS substrate enabled multiple reflections of incident laser light. • We obtained strong SERS enhancement from nanopillar-on-pyramid SERS substrate. - Abstract: A high surface area and low reflection textured surface-enhanced Raman scattering (SERS) substrate with plasmonic gold nanodroplets fabricated by wet etching and island lithography was reported in the present study. Specifically, four textured substrates, planar, pyramid, nanopillar, and nanopillar-on-pyramid, were fabricated. The fabricated structures were simulated using the finite-difference time-domain method and the results agreed with the reflection and dark-field scattering measurements. Although the SERS signals varied in different measured regions because of the random nanostructure, the SERS substrates with nanopillar-on-pyramid structure always have the stronger enhancement factor than the SERS substrates with only pyramids or nanopillars. Based on the atomic force microscope and reflection measurements, the nanopillar-on-pyramid structure provided a large surface area and multiple reflections for SERS enhancement, which was about 3 orders of magnitude larger than that of the planar substrate. Our results can be applied to fabricate the inexpensive, large surface area, and high SERS enhancement substrates.

  5. Random matrices and random difference equations

    International Nuclear Information System (INIS)

    Uppuluri, V.R.R.

    1975-01-01

    Mathematical models leading to products of random matrices and random difference equations are discussed. A one-compartment model with random behavior is introduced, and it is shown how the average concentration in the discrete time model converges to the exponential function. This is of relevance to understanding how radioactivity gets trapped in bone structure in blood--bone systems. The ideas are then generalized to two-compartment models and mammillary systems, where products of random matrices appear in a natural way. The appearance of products of random matrices in applications in demography and control theory is considered. Then random sequences motivated from the following problems are studied: constant pulsing and random decay models, random pulsing and constant decay models, and random pulsing and random decay models

  6. Reflection groups

    International Nuclear Information System (INIS)

    Eggermont, G.

    2006-01-01

    In 2005, PISA organised proactive meetings of reflection groups on involvement in decision making, expert culture and ethical aspects of radiation protection.All reflection group meetings address particular targeted audiences while the output publication in book form is put forward

  7. Random distributed feedback fibre lasers

    Energy Technology Data Exchange (ETDEWEB)

    Turitsyn, Sergei K., E-mail: s.k.turitsyn@aston.ac.uk [Aston Institute of Photonic Technologies, Aston University, Birmingham B4 7ET (United Kingdom); Novosibirsk State University, 2 Pirogova str., 630090, Novosibirsk (Russian Federation); Babin, Sergey A. [Novosibirsk State University, 2 Pirogova str., 630090, Novosibirsk (Russian Federation); Institute of Automation and Electrometry SB RAS, 1 Ac. Koptug. ave., 630090, Novosibirsk (Russian Federation); Churkin, Dmitry V. [Aston Institute of Photonic Technologies, Aston University, Birmingham B4 7ET (United Kingdom); Novosibirsk State University, 2 Pirogova str., 630090, Novosibirsk (Russian Federation); Institute of Automation and Electrometry SB RAS, 1 Ac. Koptug. ave., 630090, Novosibirsk (Russian Federation); Vatnik, Ilya D.; Nikulin, Maxim [Institute of Automation and Electrometry SB RAS, 1 Ac. Koptug. ave., 630090, Novosibirsk (Russian Federation); Podivilov, Evgenii V. [Novosibirsk State University, 2 Pirogova str., 630090, Novosibirsk (Russian Federation); Institute of Automation and Electrometry SB RAS, 1 Ac. Koptug. ave., 630090, Novosibirsk (Russian Federation)

    2014-09-10

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

  8. Random distributed feedback fibre lasers

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  9. Liberating Moral Reflection

    Science.gov (United States)

    Horell, Harold D.

    2013-01-01

    The author argues that if we are to foster life-giving and liberating moral reflection, we must first liberate moral reflection from distortions; specifically, from the distorting effects of moral insensitivity, destructive moral relativism, and confusions resulting from a failure to understand the dynamics of moral reflection. The author proposes…

  10. Reflection ciphers

    DEFF Research Database (Denmark)

    Boura, Christina; Canteaut, Anne; Knudsen, Lars Ramkilde

    2017-01-01

    study the necessary properties for this coupling permutation. Special care has to be taken of some related-key distinguishers since, in the context of reflection ciphers, they may provide attacks in the single-key setting.We then derive some criteria for constructing secure reflection ciphers...

  11. Random walk on random walks

    NARCIS (Netherlands)

    Hilário, M.; Hollander, den W.Th.F.; Sidoravicius, V.; Soares dos Santos, R.; Teixeira, A.

    2014-01-01

    In this paper we study a random walk in a one-dimensional dynamic random environment consisting of a collection of independent particles performing simple symmetric random walks in a Poisson equilibrium with density ¿¿(0,8). At each step the random walk performs a nearest-neighbour jump, moving to

  12. Additive non-uniform random sampling in superimposed fiber Bragg grating strain gauge

    Science.gov (United States)

    Ma, Y. C.; Liu, H. Y.; Yan, S. B.; Yang, Y. H.; Yang, M. W.; Li, J. M.; Tang, J.

    2013-05-01

    This paper demonstrates an additive non-uniform random sampling and interrogation method for dynamic and/or static strain gauge using a reflection spectrum from two superimposed fiber Bragg gratings (FBGs). The superimposed FBGs are designed to generate non-equidistant space of a sensing pulse train in the time domain during dynamic strain gauge. By combining centroid finding with smooth filtering methods, both the interrogation speed and accuracy are improved. A 1.9 kHz dynamic strain is measured by generating an additive non-uniform randomly distributed 2 kHz optical sensing pulse train from a mean 500 Hz triangular periodically changing scanning frequency.

  13. Evaluation of retro-reflective coating performance by reflectance and perceived relative brightness measurements

    International Nuclear Information System (INIS)

    Luse, Kaiva; Pausus, Anete; Karitans, Varis; Ozolins, Maris; Tukisa, Madara

    2011-01-01

    Retro-reflective properties of six types and five different colors or retro-reflective materials were discussed in this paper. Reflectance optical indicatrix of samples was determined and compared to obtained psychophyisical data of perceived brightness of human observer. Microscopic structure of the retro-reflective active regions of RR's was studied. Statistically significant differences in reflectivity and brightness of various types and colors of RR's were found.

  14. Random or referral hiring: When social connections matter

    OpenAIRE

    Nicodemo, Catia; Nicolini, Rosella

    2012-01-01

    This study investigates the existence of hiring criteria associated with the degree of social connections between skill and low-skill workers. We provide evidence about to what extent managers rely on their social connections in recruiting low-skill workers rather than on random matching. As one unique feature we follow an approach for a posted wage setting that reflects the main features of the Spanish labor market. By working with sub-samples of high and low-skill workers we are able to ass...

  15. Reflective writing: the student nurse's perspective on reflective writing and poetry writing.

    Science.gov (United States)

    Coleman, Dawn; Willis, Diane S

    2015-07-01

    Reflective writing is a mandatory part of nurse education but how students develop their skills and use reflection as part of their experiential learning remains relatively unknown. Understanding reflective writing in all forms from the perspective of a student nurse is therefore important. To explore the use of reflective writing and the use of poetry in pre-registered nursing students. A qualitative design was employed to explore reflective writing in pre-registered nursing students. A small university in Scotland. BSc (Hons) Adult and Mental Health Pre-registration Student Nurses. Two focus groups were conducted with 10 student nurses during March 2012. Data was analysed thematically using the framework of McCarthy (1999). Students found the process of reflective writing daunting but valued it over time. Current educational methods, such as assessing reflective accounts, often lead to the 'narrative' being watered down and the student feeling judged. Despite this, reflection made students feel responsible for their own learning and research on the topic. Some students felt the use of models of reflection constricting, whilst poetry freed up their expression allowing them to demonstrate the compassion for their patient under their care. Poetry writing gives students the opportunity for freedom of expression, personal satisfaction and a closer connection with their patients, which the more formal approach to reflective writing did not offer. There is a need for students to have a safe and supportive forum in which to express and have their experiences acknowledged without the fear of being judged. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  16. Organic petrology and geochemistry of the Carboniferous coal seams from the Central Asturian Coal Basin (NW Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Piedad-Sanchez, Noe; Martinez, Luis; Izart, Alain; Elie, Marcel [UMR G2R/7566, Geologie et Gestion des Ressources Minerales et Energetiques, Faculte des Sciences, Universite Henri Poincare, Nancy 1, BP-239, Boulevard des Aiguillettes, Vandoeuvre-les-Nancy Cedex 54506 (France); Suarez-Ruiz, Isabel [Instituto Nacional del Carbon (CSIC), C/ Francisco Pintado Fe, 26, Ap. Co., 73, Oviedo 33011 (Spain); Keravis, Didier [Institut des Sciences de la Terre (ISTO), CNRS-Universite d' Orleans, Batiment Geosciences, BP 6759, Orleans 45067 (France)

    2004-03-23

    This paper presents for the first time a petrological and geochemical study of coals from the Central Asturian Coal Basin (North Spain) of Carboniferous (Pennsylvanian), mainly of Moscovian, age. A paleoenvironmental approach was used, taking into account both petrographic and organic geochemical studies. Vitrinite reflectance (R{sub r}) ranges from 0.5% to 2.5%, which indicates a high volatile bituminous to semianthracite and anthracite coal rank. The coal samples selected for paleoenvironmental reconstruction are located inside the oil-gas-prone phase, corresponding to the interval between the onset of oil generation and first gas generation and efficient expulsion of oil. This phase is represented by coals that have retained their hydrocarbon potential and also preserved biomarker information. Paleodepositional reconstruction based on maceral and petrographic indices points to a swamp environment with vitrinite-rich coal facies and variable mineral matter content. The gelification index (GI) and groundwater influence index (GWI) indicate strong gelification and wet conditions. The biomarkers exhibit a high pristane/phytane ratio, suggesting an increase in this ratio from diagenetic processes, and a high diterpanes ratio. This, in turn, would seem to indicate a high swamp water table and a humid climate. The maximum point of coal accumulation occurred during the regressive part of the Late Moscovian sequence and in the most humid climate described for this period of time in the well-known coal basins of Europe and North America.

  17. Evaluation of retro-reflective coating performance by reflectance and perceived relative brightness measurements

    Energy Technology Data Exchange (ETDEWEB)

    Luse, Kaiva; Pausus, Anete; Karitans, Varis; Ozolins, Maris; Tukisa, Madara, E-mail: kaiva.luse@gmail.com [University of Latvia, Optometry and Vision Science Department, Kengaraga street 8, Riga LV-1063 (Latvia)

    2011-06-23

    Retro-reflective properties of six types and five different colors or retro-reflective materials were discussed in this paper. Reflectance optical indicatrix of samples was determined and compared to obtained psychophyisical data of perceived brightness of human observer. Microscopic structure of the retro-reflective active regions of RR's was studied. Statistically significant differences in reflectivity and brightness of various types and colors of RR's were found.

  18. On pricing futures options on random binomial tree

    International Nuclear Information System (INIS)

    Bayram, Kamola; Ganikhodjaev, Nasir

    2013-01-01

    The discrete-time approach to real option valuation has typically been implemented in the finance literature using a binomial tree framework. Instead we develop a new model by randomizing the environment and call such model a random binomial tree. Whereas the usual model has only one environment (u, d) where the price of underlying asset can move by u times up and d times down, and pair (u, d) is constant over the life of the underlying asset, in our new model the underlying security is moving in two environments namely (u 1 , d 1 ) and (u 2 , d 2 ). Thus we obtain two volatilities σ 1 and σ 2 . This new approach enables calculations reflecting the real market since it consider the two states of market normal and extra ordinal. In this paper we define and study Futures options for such models.

  19. Source rock potential of the organic rich Turonian - Upper Campanian carbonates of northern Lebanon

    Energy Technology Data Exchange (ETDEWEB)

    Daher, S. Bou; Littke, R. [RWTH Aachen Univ. (Germany). Energy and Mineral Resources Group (EMR); Nader, F.H. [IFP Energies nouvelles, Paris (France). Dept. of Sedimentology-Stratigraphy

    2013-08-01

    Upper Cretaceous chalks, marls, and shales are arguably the most prolific petroleum source rocks in the eastern Mediterranean region. 209 core samples from the Turonian - Upper Campanian rock succession in north Lebanon were collected and analyzed for their organic matter (OM) content, quality, and maturity. The total organic carbon (TOC) measurements revealed a very good source rock potential for a 150 m interval within the Upper Santonian - Upper Campanian, with an average of 2% TOC. High HI values (average 707 mg/g TOC) characterize these source rocks as type I kerogen and reflect a very good preservation of the organic matter. T{sub max} values (average 421 C) match the other maturity parameters such as vitrinite reflectance (average 0.35%), and all point towards immature organic matter. The equivalent Upper Cretaceous in the offshore Levant basin has enough overburden to have reached maturity. However, the accurate extrapolation of the organic matter quality and quantity to the offshore is yet a challenge with the data at hand. (orig.)

  20. Laser absorption of carbon fiber reinforced polymer with randomly distributed carbon fibers

    Science.gov (United States)

    Hu, Jun; Xu, Hebing; Li, Chao

    2018-03-01

    Laser processing of carbon fiber reinforced polymer (CFRP) is a non-traditional machining method which has many prospective applications. The laser absorption characteristics of CFRP are analyzed in this paper. A ray tracing model describing the interaction of the laser spot with CFRP is established. The material model contains randomly distributed carbon fibers which are generated using an improved carbon fiber placement method. It was found that CFRP has good laser absorption due to multiple reflections of the light rays in the material’s microstructure. The randomly distributed carbon fibers make the absorptivity of the light rays change randomly in the laser spot. Meanwhile, the average absorptivity fluctuation is obvious during movement of the laser. The experimental measurements agree well with the values predicted by the ray tracing model.

  1. Reflection as Self-Assessment

    Science.gov (United States)

    Pappas, Marjorie L.

    2010-01-01

    In this article, the author discusses how reflection can be used as self-assessment. Reflection involves not only thinking about a learning experience, but also questioning parts of the experience. Reflection is thinking about what one knows from the learning experience, what one might do differently the next time. Reflection is wondering about…

  2. Designing a Reflective Teacher Education Course and Its Contribution to ELT Teachers' Reflectivity

    Science.gov (United States)

    Tajik, Leila; Pakzad, Kazem

    2016-01-01

    Researchers in the present study planned a reflective teacher education course and documented the contribution of such a course to improving teachers' reflectivity. Five English teachers took part in the reflective teacher education course designed by the researchers. To record how the course could help improve reflective teaching, researchers…

  3. Can reflecting on personal values online increase positive beliefs about counseling?

    Science.gov (United States)

    Lannin, Daniel G; Vogel, David L; Heath, Patrick J

    2017-04-01

    This research developed and tested an online values-affirmation exercise to attenuate threat and enhance positive beliefs about counseling among individuals struggling with mental health concerns. There is evidence that reflecting on personal values (values-affirmation) is an effective approach to eliciting self-affirmation-a psychological process that temporarily bolsters self-worth in order to forestall maladaptive, self-protective responses to counseling information. The present study utilized a randomized 2-group between-subjects design to test the effectiveness of a values-affirmation exercise with an online sample (N = 186) of adults who reported struggling with a mental health concern. It was predicted that values-affirmation would reduce threat related to reading mental health information and increase positive beliefs about counseling. Results indicated that those in the values-affirmation condition reported fewer negative emotions such as feeling upset, irritable, hostile, and scared after reading mental health information, indicating that the information was perceived as less threatening. There was also evidence that engaging in values-affirmation was associated with greater anticipated growth in counseling and greater intent to seek counseling, reflecting greater positive beliefs about counseling. Overall, the results suggest that reflecting on personal values may have the potential to enhance the positive effects of online psychoeducation. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  4. Self-Reflection

    DEFF Research Database (Denmark)

    Fausing, Bent

    2016-01-01

    will take a look at the establishing of the modern self and possibilities of self-reflection, too. My examples will be from the so-called dark-selfies and from a new selfie form, which merge the present with the previous progressing into the future. I will discuss the media reflections as loos and/or gain...

  5. Personal Reflections

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education. Personal Reflections. Articles in Resonance – Journal of Science Education. Volume 6 Issue 3 March 2001 pp 90-93 Personal Reflections. Why did I opt for Career in Science? Jayant V Narlikar · More Details Fulltext PDF. Volume 9 Issue 8 August 2004 pp 89-89 ...

  6. Stochastic Gabor reflectivity and acoustic impedance inversion

    Science.gov (United States)

    Hariri Naghadeh, Diako; Morley, Christopher Keith; Ferguson, Angus John

    2018-02-01

    To delineate subsurface lithology to estimate petrophysical properties of a reservoir, it is possible to use acoustic impedance (AI) which is the result of seismic inversion. To change amplitude to AI, removal of wavelet effects from the seismic signal in order to get a reflection series, and subsequently transforming those reflections to AI, is vital. To carry out seismic inversion correctly it is important to not assume that the seismic signal is stationary. However, all stationary deconvolution methods are designed following that assumption. To increase temporal resolution and interpretation ability, amplitude compensation and phase correction are inevitable. Those are pitfalls of stationary reflectivity inversion. Although stationary reflectivity inversion methods are trying to estimate reflectivity series, because of incorrect assumptions their estimations will not be correct, but may be useful. Trying to convert those reflection series to AI, also merging with the low frequency initial model, can help us. The aim of this study was to apply non-stationary deconvolution to eliminate time variant wavelet effects from the signal and to convert the estimated reflection series to the absolute AI by getting bias from well logs. To carry out this aim, stochastic Gabor inversion in the time domain was used. The Gabor transform derived the signal’s time-frequency analysis and estimated wavelet properties from different windows. Dealing with different time windows gave an ability to create a time-variant kernel matrix, which was used to remove matrix effects from seismic data. The result was a reflection series that does not follow the stationary assumption. The subsequent step was to convert those reflections to AI using well information. Synthetic and real data sets were used to show the ability of the introduced method. The results highlight that the time cost to get seismic inversion is negligible related to general Gabor inversion in the frequency domain. Also

  7. Enhancing medical students' reflectivity in mentoring groups for professional development - a qualitative analysis.

    Science.gov (United States)

    Lutz, Gabriele; Pankoke, Nina; Goldblatt, Hadass; Hofmann, Marzellus; Zupanic, Michaela

    2017-07-14

    Professional competence is important in delivering high quality patient care, and it can be enhanced by reflection and reflective discourse e.g. in mentoring groups. However, students are often reluctant though to engage in this discourse. A group mentoring program involving all preclinical students as well as faculty members and co-mentoring clinical students was initiated at Witten-Herdecke University. This study explores both the attitudes of those students towards such a program and factors that might hinder or enhance how students engage in reflective discourse. A qualitative design was applied using semi-structured focus group interviews with preclinical students and semi-structured individual interviews with mentors and co-mentors. The interview data were analyzed using thematic content analysis. Students' attitudes towards reflective discourse on professional challenges were diverse. Some students valued the new program and named positive outcomes regarding several features of professional development. Enriching experiences were described. Others expressed aversive attitudes. Three reasons for these were given: unclear goals and benefits, interpersonal problems within the groups hindering development and intrapersonal issues such as insecurity and traditional views of medical education. Participants mentioned several program setup factors that could enhance how students engage in such groups: explaining the program thoroughly, setting expectations and integrating the reflective discourse in a meaningful way into the curriculum, obliging participation without coercion, developing a sense of security, trust and interest in each other within the groups, randomizing group composition and facilitating group moderators as positive peer and faculty role models and as learning group members. A well-designed and empathetic setup of group mentoring programs can help raise openness towards engaging in meaningful reflective discourse. Reflection on and communication of

  8. The interplay of self-reflection, social interaction and random events in the dynamics of opinion flow in two-party democracies

    Science.gov (United States)

    Lichtenegger, Klaus; Hadzibeganovic, Tarik

    2016-01-01

    We propose a continuous process opinion formation model to study the dynamics of a multi-level relationship between voters, political parties, and facts in two-party democratic elections. In our model, opinions can take any real value between two extremes and an unaligned, moderate opinion state without a preference. Starting with a random opinion configuration, individual voter opinions evolve and change over time due to self-reflection, inter-personal communication, external media influence, and noise. Parties are influenced by their own ideologies, facts, and voters’ opinions. Elections are held periodically and the party that is closer in opinion to the majority of voters forms the new government. The government policy is then expected to be in proximity to the voter opinions and the policies of the currently ruling political party. We analyze the tension of opinions as a measure of how dramatically opinions can disagree within a given sample of voters and the success of the government and parties as the degree of coincidence between the policies and facts. Our model generates realistic quasi-periodic alternations between incumbents and challengers that are typical for two-party systems. Moreover, our model shows that relative to other voters’ strategies, conscious voting can lead to more successful governments of not only fact-oriented but also pragmatic and balanced political parties, irrespective of the strategies of the competing opposition parties. In addition, our simulations uncover several interesting features including less victories for strictly ideological or fact-oriented parties unless they include some aspects of populism or pragmatism. In this sense, our model can also describe situations where election outcomes are not necessarily based on votes for the current programs of competing parties and their placement on relevant issues, but instead result from voters’ dissatisfaction with the previous government and the votes against it.

  9. Metacognitive reflection and insight therapy (MERIT) for patients with schizophrenia.

    Science.gov (United States)

    de Jong, S; van Donkersgoed, R J M; Timmerman, M E; Aan Het Rot, M; Wunderink, L; Arends, J; van Der Gaag, M; Aleman, A; Lysaker, P H; Pijnenborg, G H M

    2018-04-25

    Impaired metacognition is associated with difficulties in the daily functioning of people with psychosis. Metacognition can be divided into four domains: Self-Reflection, Understanding the Other's Mind, Decentration, and Mastery. This study investigated whether Metacognitive Reflection and Insight Therapy (MERIT) can be used to improve metacognition. This study is a randomized controlled trial. Patients in the active condition (n = 35) received forty MERIT sessions, the control group (n = 35) received treatment as usual. Multilevel intention-to-treat and completers analyses were performed for metacognition and secondary outcomes (psychotic symptomatology, cognitive insight, Theory of Mind, empathy, depression, self-stigma, quality of life, social functioning, and work readiness). Eighteen out of 35 participants finished treatment, half the drop-out stemmed from therapist attrition (N = 5) or before the first session (N = 4). Intention-to-treat analysis demonstrated that in both groups metacognition improved between pre- and post-measurements, with no significant differences between the groups. Patients who received MERIT continued to improve, while the control group returned to baseline, leading to significant differences at follow-up. Completers analysis (18/35) showed improvements on the Metacognition Assessment Scale (MAS-A) scales Self Reflectivity and metacognitive Mastery at follow-up. No effects were found on secondary outcomes. On average, participants in the MERIT group were, based on MAS-A scores, at follow-up more likely to recognize their thoughts as changeable rather than as facts. MERIT might be useful for patients whose self-reflection is too limited to benefit from other therapies. Given how no changes were found in secondary measures, further research is needed. Limitations and suggestions for future research are discussed.

  10. Epigenetic-hydrothermal origin of the sediment-hosted Muellenbach uranium deposit, Baden-Baden, W-Germany

    International Nuclear Information System (INIS)

    Brockamp, O.; Zuther, M.; Clauer, N.

    1987-01-01

    Upper Carboniferous sediments on the margin of the northern Black Forest granite massif are the host rocks of the Muellenbach uranium deposit. According to K/Ar datings the sericites formed during the Jurassic (150 Ma), an age also interpreted from U/Pb ratios for the crystallization of the pitchblende. Based on vitrinite reflectance the mineralization temperature is estimated to be 240 0 -290 0 C. It is postulated that the hydrothermal solutions were supplied via deep-seated faults bordering and crosscutting the granite massif and the sedimentary trough which is an intramontane basin. In its immediate vicinity the rift valley of the Rhein graben developed. Uranium deposits in comparable settings are supposed to be predominately of epigenetic-hydrothermal origin. (orig./HP)

  11. Carbonaceous matter in the Pomozhan deposit

    Energy Technology Data Exchange (ETDEWEB)

    Piatek, G

    1979-01-01

    Carbonaceous matter (CM), encountered in the Pomozhan deposit, is coordinate to dolomitic-illitic clay, filling caverns in ore-bearing dolomites. The CM represents a disperse mass with particle sizes up to 2 mm, having a color from dark brown to black. The reflectivity (0.35-0.42%) and classification assignment of the CM to macerals of the vitrinite or dopplerinite group were determined by micropetrographic methods. CM belonging to the type of humic coals, transitional from brown to bituminous coals is an epigenetic formation. Its accumulation in the regions of the Ol'kush ore deposits occurred in the Triassic-Cretaceous or Cenozoic interval. Liassic coal of the Zavertse region or Helvetian coal of Khomentuv and Tarnobzheg could be the source of the CM.

  12. Thermal history of the multi-well experiment (MWX) site, Piceance Creek Basin, Northwestern Colorado, derived from fission-track analysis

    International Nuclear Information System (INIS)

    Kelley, S.A.; Blackwell, D.D.

    1990-01-01

    Fission-track analysis of apatite and zircon from 19 depth intervals in two drill holes at the MWX site in the Piceance Creek Basin, Colorado, is used to determine the burial and subsequent cooling history of the Upper Cretaceous Mesaverde Group and the Paleocene Wasatch Formation. The fission-track data, as well as available temperature, vitrinite reflectance, and geological information, indicate that the sampled sediments attained maximum burial at approximately 10 Ma, with maximum temperatures in the 150-200 0 C range. After 10 Ma the sediments began to cool during erosion related to the downcutting of the Colorado River, which lies just to the north of the MWX site. The heat flow in this area has remained relatively constant for the past 10 Ma. (author)

  13. Organic maturation levels, thermal history and hydrocarbon source rock potential of the Namurian rocks of the Clare Basin, Ireland

    Energy Technology Data Exchange (ETDEWEB)

    Goodhue, Robbie; Clayton, Geoffrey [Trinity Coll., Dept. of Geology, Dublin (Ireland)

    1999-11-01

    Vitrinite reflectance data from two inland cored boreholes confirm high maturation levels throughout the onshore part of the Irish Clare Basin and suggest erosion of 2 to 4 km of late Carboniferous cover and elevated palaeogeothermal gradients in the Carboniferous section. The observed maturation gradients are fully consistent with the published hypothesis of a late Carboniferous/Permian 'superplume' beneath Pangaea but local vertical reversals in gradients also suggest a complex thermal regime probably involving advective heating. The uppermost Visean--lower Namurian Clare Shale is laterally extensive and up to 300 m thick. Although this unit is post-mature, TOC values of up to 15% suggest that it could have considerable hydrocarbon source rock potential in any less mature offshore parts of the basin. (Author)

  14. Thermal Maturity Data Used by the U.S. Geological Survey for the U.S. Gulf Coast Region Oil and Gas Assessment

    Science.gov (United States)

    Dennen, Kristin O.; Warwick, Peter D.; McDade, Elizabeth Chinn

    2010-01-01

    The U.S. Geological Survey is currently assessing the oil and natural gas resources of the U.S. Gulf of Mexico region using a total petroleum system approach. An essential part of this geologically based method is evaluating the effectiveness of potential source rocks in the petroleum system. The purpose of this report is to make available to the public RockEval and vitrinite reflectance data from more than 1,900 samples of Mesozoic and Tertiary rock core and coal samples in the Gulf of Mexico area in a format that facilitates inclusion into a geographic information system. These data provide parameters by which the thermal maturity, type, and richness of potential sources of oil and gas in this region can be evaluated.

  15. Additive non-uniform random sampling in superimposed fiber Bragg grating strain gauge

    International Nuclear Information System (INIS)

    Ma, Y C; Liu, H Y; Yan, S B; Li, J M; Tang, J; Yang, Y H; Yang, M W

    2013-01-01

    This paper demonstrates an additive non-uniform random sampling and interrogation method for dynamic and/or static strain gauge using a reflection spectrum from two superimposed fiber Bragg gratings (FBGs). The superimposed FBGs are designed to generate non-equidistant space of a sensing pulse train in the time domain during dynamic strain gauge. By combining centroid finding with smooth filtering methods, both the interrogation speed and accuracy are improved. A 1.9 kHz dynamic strain is measured by generating an additive non-uniform randomly distributed 2 kHz optical sensing pulse train from a mean 500 Hz triangular periodically changing scanning frequency. (paper)

  16. How random is a random vector?

    International Nuclear Information System (INIS)

    Eliazar, Iddo

    2015-01-01

    Over 80 years ago Samuel Wilks proposed that the “generalized variance” of a random vector is the determinant of its covariance matrix. To date, the notion and use of the generalized variance is confined only to very specific niches in statistics. In this paper we establish that the “Wilks standard deviation” –the square root of the generalized variance–is indeed the standard deviation of a random vector. We further establish that the “uncorrelation index” –a derivative of the Wilks standard deviation–is a measure of the overall correlation between the components of a random vector. Both the Wilks standard deviation and the uncorrelation index are, respectively, special cases of two general notions that we introduce: “randomness measures” and “independence indices” of random vectors. In turn, these general notions give rise to “randomness diagrams”—tangible planar visualizations that answer the question: How random is a random vector? The notion of “independence indices” yields a novel measure of correlation for Lévy laws. In general, the concepts and results presented in this paper are applicable to any field of science and engineering with random-vectors empirical data.

  17. How random is a random vector?

    Science.gov (United States)

    Eliazar, Iddo

    2015-12-01

    Over 80 years ago Samuel Wilks proposed that the "generalized variance" of a random vector is the determinant of its covariance matrix. To date, the notion and use of the generalized variance is confined only to very specific niches in statistics. In this paper we establish that the "Wilks standard deviation" -the square root of the generalized variance-is indeed the standard deviation of a random vector. We further establish that the "uncorrelation index" -a derivative of the Wilks standard deviation-is a measure of the overall correlation between the components of a random vector. Both the Wilks standard deviation and the uncorrelation index are, respectively, special cases of two general notions that we introduce: "randomness measures" and "independence indices" of random vectors. In turn, these general notions give rise to "randomness diagrams"-tangible planar visualizations that answer the question: How random is a random vector? The notion of "independence indices" yields a novel measure of correlation for Lévy laws. In general, the concepts and results presented in this paper are applicable to any field of science and engineering with random-vectors empirical data.

  18. Randomized random walk on a random walk

    International Nuclear Information System (INIS)

    Lee, P.A.

    1983-06-01

    This paper discusses generalizations of the model introduced by Kehr and Kunter of the random walk of a particle on a one-dimensional chain which in turn has been constructed by a random walk procedure. The superimposed random walk is randomised in time according to the occurrences of a stochastic point process. The probability of finding the particle in a particular position at a certain instant is obtained explicitly in the transform domain. It is found that the asymptotic behaviour for large time of the mean-square displacement of the particle depends critically on the assumed structure of the basic random walk, giving a diffusion-like term for an asymmetric walk or a square root law if the walk is symmetric. Many results are obtained in closed form for the Poisson process case, and these agree with those given previously by Kehr and Kunter. (author)

  19. Near zero reflection by nanostructured anti-reflection coating design for Si substrates

    Science.gov (United States)

    Al-Fandi, Mohamed; Makableh, Yahia F.; Khasawneh, Mohammad; Rabady, Rabi

    2018-05-01

    The nanostructure design of near zero reflection coating for Si substrates by using ZnO Nanoneedles (ZnONN) is performed and optimized for the visible spectral range. The design investigates the ZnONN tip to body ratio effect on the anti-reflection coating properties. Different tip to body ratios are used on Si substrates. Around zero reflection is achieved by the Nanoneedles structure design presented in this work, leading to minimal reflection losses from the Si surface. The current design evolves a solution to optical losses and surface contamination effects associated with Si solar cells.

  20. Mechanisms within the Parietal Cortex Correlate with the Benefits of Random Practice in Motor Adaptation

    Directory of Open Access Journals (Sweden)

    Benjamin Thürer

    2017-08-01

    Full Text Available The motor learning literature shows an increased retest or transfer performance after practicing under unstable (random conditions. This random practice effect (also known as contextual interference effect is frequently investigated on the behavioral level and discussed in the context of mechanisms of the dorsolateral prefrontal cortex and increased cognitive efforts during movement planning. However, there is a lack of studies examining the random practice effect in motor adaptation tasks and, in general, the underlying neural processes of the random practice effect are not fully understood. We tested 24 right-handed human subjects performing a reaching task using a robotic manipulandum. Subjects learned to adapt either to a blocked or a random schedule of different force field perturbations while subjects’ electroencephalography (EEG was recorded. The behavioral results showed a distinct random practice effect in terms of a more stabilized retest performance of the random compared to the blocked practicing group. Further analyses showed that this effect correlates with changes in the alpha band power in electrodes over parietal areas. We conclude that the random practice effect in this study is facilitated by mechanisms within the parietal cortex during movement execution which might reflect online feedback mechanisms.

  1. Strategic Resource Use for Learning: A Self-Administered Intervention That Guides Self-Reflection on Effective Resource Use Enhances Academic Performance.

    Science.gov (United States)

    Chen, Patricia; Chavez, Omar; Ong, Desmond C; Gunderson, Brenda

    2017-06-01

    Many educational policies provide learners with more resources (e.g., new learning activities, study materials, or technologies), but less often do they address whether students are using these resources effectively. We hypothesized that making students more self-reflective about how they should approach their learning with the resources available to them would improve their class performance. We designed a novel Strategic Resource Use intervention that students could self-administer online and tested its effects in two cohorts of a college-level introductory statistics class. Before each exam, students randomly assigned to the treatment condition strategized about which academic resources they would use for studying, why each resource would be useful, and how they would use their resources. Students randomly assigned to the treatment condition reported being more self-reflective about their learning throughout the class, used their resources more effectively, and outperformed students in the control condition by an average of one third of a letter grade in the class.

  2. Postgraduate Education to Support Organisation Change: A Reflection on Reflection

    Science.gov (United States)

    Stewart, Jim; Keegan, Anne; Stevens, Pam

    2008-01-01

    Purpose: This paper aims to explore how teaching and assessing reflective learning skills can support postgraduate practitioners studying organisational change and explores the challenges for tutors in assessing these journals. Design/methodology/approach: Assessment criteria were developed from the literature on reflective practice and…

  3. Sequential fitting-and-separating reflectance components for analytical bidirectional reflectance distribution function estimation.

    Science.gov (United States)

    Lee, Yu; Yu, Chanki; Lee, Sang Wook

    2018-01-10

    We present a sequential fitting-and-separating algorithm for surface reflectance components that separates individual dominant reflectance components and simultaneously estimates the corresponding bidirectional reflectance distribution function (BRDF) parameters from the separated reflectance values. We tackle the estimation of a Lafortune BRDF model, which combines a nonLambertian diffuse reflection and multiple specular reflectance components with a different specular lobe. Our proposed method infers the appropriate number of BRDF lobes and their parameters by separating and estimating each of the reflectance components using an interval analysis-based branch-and-bound method in conjunction with iterative K-ordered scale estimation. The focus of this paper is the estimation of the Lafortune BRDF model. Nevertheless, our proposed method can be applied to other analytical BRDF models such as the Cook-Torrance and Ward models. Experiments were carried out to validate the proposed method using isotropic materials from the Mitsubishi Electric Research Laboratories-Massachusetts Institute of Technology (MERL-MIT) BRDF database, and the results show that our method is superior to a conventional minimization algorithm.

  4. Reflection and Reflective Practice Discourses in Coaching: A Critical Analysis

    Science.gov (United States)

    Cushion, Christopher J.

    2018-01-01

    Reflection and reflective practice is seen as an established part of coaching and coach education practice. It has become a "taken-for-granted" part of coaching that is accepted enthusiastically and unquestioningly, and is assumed to be "good" for coaching and coaches. Drawing on sociological concepts, a primarily Foucauldian…

  5. Another Look at the Draft Mil-Std-1540E Unit Random Vibration Test Requirements

    Science.gov (United States)

    Perl, E.; Peterson, A. J..; Davis, D.

    2012-07-01

    The draft Mil-Std-1540E has been updated to reflect lessons learned since its publication as an SMC Standard in 2008, [1], and an earlier Aerospace Corporation Technical Report released in 2006, [2]. This paper discusses the technical rationale supporting some of the unit random vibration test requirements to provide better insight into their derivation and application to programs. It is intended that these requirements be tailored for each program to reflect the customer risk profile. Several tailoring options are provided and a two phase test strategy is discussed to highlight its applicability to utilizing heritage hardware in new applications.

  6. Obtaining local reflectivity at two-way travel time by filtering acoustic reflection data

    NARCIS (Netherlands)

    Slob, E.C.; Zhang, L.; Wapenaar, C.P.A.; Mihai Popovici, A.; Fomel, S.

    2017-01-01

    A modified implementation of Marchenko redatuming leads to a filter that removes internal multiples from reflection data. It produces local reflectivity at two-way travel time. The method creates new primary reflections resulting from emitted events that eliminate internal multiples. We call these

  7. Reflective Practices for Teacher Education

    Directory of Open Access Journals (Sweden)

    Paulus Kuswandono

    2017-01-01

    Full Text Available Studies on reflective practice in teacher education are increasingly getting more attention at least in the last 2 decades. This article discusses concepts of reflection and how it is implemented in educating pre-service teachers on their early stage of professional learning. The purposes of doing the reflection for pre-service teachers are not only for illuminating their professional learning experiences, but also to critically reflect their vocation as teachers, including the values which may be dictated to them through rigid regulations. Reflection in teacher education is crucial as it connects well with learning in that learners use reflection to exercise their mind and to evaluate their learning experiences. Besides, this article also highlights some perceived difficulties to implement reflective practice, as well as ways how to promote reflection.   DOI: https://doi.org/10.24071/llt.2012.150102

  8. Catheter based mid-infrared reflectance and reflectance generated absorption spectroscopy

    Science.gov (United States)

    Holman, Hoi-Ying N

    2013-10-29

    A method of characterizing conditions in a tissue, by (a) providing a catheter that has a light source that emits light in selected wavenumbers within the range of mid-IR spectrum; (b) directing the light from the catheter to an area of tissue at a location inside a blood vessel of a subject; (c) collecting light reflected from the location and generating a reflectance spectra; and (d) comparing the reflectance spectra to a reference spectra of normal tissue, whereby a location having an increased number of absorbance peaks at said selected wavenumbers indicates a tissue inside the blood vessel containing a physiological marker for atherosclerosis.

  9. Studies of the Reflection, Refraction and Internal Reflection of Light

    Science.gov (United States)

    Lanchester, P. C.

    2014-01-01

    An inexpensive apparatus and associated experiments are described for studying the basic laws of reflection and refraction of light at an air-glass interface, and multiple internal reflections within a glass block. In order to motivate students and encourage their active participation, a novel technique is described for determining the refractive…

  10. Self-rumination, self-reflection, and depression: self-rumination counteracts the adaptive effect of self-reflection.

    Science.gov (United States)

    Takano, Keisuke; Tanno, Yoshihiko

    2009-03-01

    Self-focused attention has adaptive and maladaptive aspects: self-reflection and self-rumination [Trapnell, P. D., & Campbell, J. D. (1999). Private self-consciousness and the Five-Factor Model of personality: distinguishing rumination from reflection. Journal of Personality and Social Psychology, 76, 284-304]. Although reflection is thought to be associated with problem solving and the promotion of mental health, previous researches have shown that reflection does not always have an adaptive effect on depression. Authors have examined the causes behind this inconsistency by modeling the relationships among self-reflection, self-rumination, and depression. One hundred and eleven undergraduates (91 men and 20 women) participated in a two-time point assessment with a 3-week interval. Statistical analysis with structural equation modeling showed that self-reflection significantly predicted self-rumination, whereas self-rumination did not predict self-reflection. With regard to depression, self-reflection was associated with a lower level of depression; self-rumination, with a higher level of depression. The total effect of self-reflection on depression was almost zero. This result indicates that self-reflection per se has an adaptive effect, which is canceled out by the maladaptive effect of self-rumination, because reflectors are likely to ruminate and reflect simultaneously.

  11. Random broadcast on random geometric graphs

    Energy Technology Data Exchange (ETDEWEB)

    Bradonjic, Milan [Los Alamos National Laboratory; Elsasser, Robert [UNIV OF PADERBORN; Friedrich, Tobias [ICSI/BERKELEY; Sauerwald, Tomas [ICSI/BERKELEY

    2009-01-01

    In this work, we consider the random broadcast time on random geometric graphs (RGGs). The classic random broadcast model, also known as push algorithm, is defined as: starting with one informed node, in each succeeding round every informed node chooses one of its neighbors uniformly at random and informs it. We consider the random broadcast time on RGGs, when with high probability: (i) RGG is connected, (ii) when there exists the giant component in RGG. We show that the random broadcast time is bounded by {Omicron}({radical} n + diam(component)), where diam(component) is a diameter of the entire graph, or the giant component, for the regimes (i), or (ii), respectively. In other words, for both regimes, we derive the broadcast time to be {Theta}(diam(G)), which is asymptotically optimal.

  12. The Effect of Using Online Collaborative Tasks on Incidental Vocabulary Learning of Impulsive vs. Reflective Iranian EFL Learners

    Directory of Open Access Journals (Sweden)

    Khalil Motallebzadeh

    2017-09-01

    Full Text Available Incidental vocabulary learning is one of the most significant sources of learning vocabulary for language learners Laufer  & Hulstjin, 2001. This study endeavored to investigate the effect of using online collaborative tasks on incidental vocabulary learning of impulsive vs. reflective Iranian EFL learners. To this end, Nelson vocabulary proficiency test was administered to 100 Iranian EFL learners as the homogeneity test and the pretest. Using random sampling procedure, 75 learners were selected as the main participants for this study. Kember, McKay, Sinclair and Wong (2008 reflective thinking questionnaire was administered to these learners, based on which they were distinguished based on their cognitive thinking styles, i.e., impulsivity and reflectivity. The participants were homogenously distributed into 3 main groups (impulsive experimental group, reflective experimental group, and the control group. All participants went through 4 weeks of treatment. Experimental groups were conducted using Telegram software and the control group was conducted in a classroom. The results of t-test after 4 weeks of treatment revealed that reflective learners benefited from online collaborative groups with regard to incidental vocabulary learning. The findings of the study are discussed in light of previous research.

  13. Born reflection kernel analysis and wave-equation reflection traveltime inversion in elastic media

    KAUST Repository

    Wang, Tengfei

    2017-08-17

    Elastic reflection waveform inversion (ERWI) utilize the reflections to update the low and intermediate wavenumbers in the deeper part of model. However, ERWI suffers from the cycle-skipping problem due to the objective function of waveform residual. Since traveltime information relates to the background model more linearly, we use the traveltime residuals as objective function to update background velocity model using wave equation reflected traveltime inversion (WERTI). The reflection kernel analysis shows that mode decomposition can suppress the artifacts in gradient calculation. We design a two-step inversion strategy, in which PP reflections are firstly used to invert P wave velocity (Vp), followed by S wave velocity (Vs) inversion with PS reflections. P/S separation of multi-component seismograms and spatial wave mode decomposition can reduce the nonlinearity of inversion effectively by selecting suitable P or S wave subsets for hierarchical inversion. Numerical example of Sigsbee2A model validates the effectiveness of the algorithms and strategies for elastic WERTI (E-WERTI).

  14. Principles of neutron reflection

    International Nuclear Information System (INIS)

    Felcher, G.P.

    1988-08-01

    Neutron reflection is perhaps the most developed branch of slow neutrons optics, which in itself is a direct consequence of the undulatory nature of the neutron. After reviewing the basic types of interactions (nuclear and magnetic) between neutrons and matter, the formalism is introduced to calculate the reflectivity from a sample composed of stacked flat layers and, inversely, to calculate the stacking from reflectivity measurements. Finally, a brief survey of the applications of neutron reflection is given, both in technology and in fundamental research. 32 refs., 6 figs

  15. Storage array reflection considerations

    International Nuclear Information System (INIS)

    Haire, M.J.; Jordan, W.C.; Taylor, R.G.

    1997-01-01

    The assumptions used for reflection conditions of single containers are fairly well established and consistently applied throughout the industry in nuclear criticality safety evaluations. Containers are usually considered to be either fully water-reflected (i.e. surrounded by 6 to 12 in. of water) for safety calculations or reflected by 1 in. of water for nominal (structural material and air) conditions. Tables and figures are usually available for performing comparative evaluations of containers under various loading conditions. Reflection considerations used for evaluating the safety of storage arrays of fissile material are not as well established

  16. Critical incident analysis through narrative reflective practice: A case study

    Directory of Open Access Journals (Sweden)

    Thomas S. C. Farrell

    2013-01-01

    Full Text Available Teachers can reflect on their practices by articulating and exploring incidents they consider critical to themselves or others. By talking about these critical incidents, teachers can make better sense of seemingly random experiences that occur in their teaching because they hold the real inside knowledge, especially personal intuitive knowledge, expertise and experience that is based on their accumulated years as language educators teaching in schools and classrooms. This paper is about one such critical incident analysis that an ESL teacher in Canada revealed to her critical friend and how both used McCabe’s (2002 narrative framework for analyzing an important critical incident that occurred in the teacher’s class.

  17. Topics in random walks in random environment

    International Nuclear Information System (INIS)

    Sznitman, A.-S.

    2004-01-01

    Over the last twenty-five years random motions in random media have been intensively investigated and some new general methods and paradigms have by now emerged. Random walks in random environment constitute one of the canonical models of the field. However in dimension bigger than one they are still poorly understood and many of the basic issues remain to this day unresolved. The present series of lectures attempt to give an account of the progresses which have been made over the last few years, especially in the study of multi-dimensional random walks in random environment with ballistic behavior. (author)

  18. Incorporating Self and Peer Assessment in Reflective Teaching Practices

    Directory of Open Access Journals (Sweden)

    Ni Made Ratminingsih

    2017-11-01

    Full Text Available More currently literature reviews suggests the use of authentic assessment, which aims to involve students to be more responsible with their learning. This article reports the findings of a descriptive study on student teachers’ perception on the use of self and peer assessment to give evaluation on planning the lesson and teaching performance in Reflective Teaching Class. There were 100 samples taken randomly from 234 students in a survey using questionnaire and 15 students participating in the focus group discussion (FGD. The finding from the questionnaire shows that they had a very positive perception toward the use of self and peer assessment. Additionally, from the FGD, they conveyed by practicing doing self assessment, they could learn to see self performance deeply, strengths and weaknesses. From peer-assessment, they could learn collaboratively from feedback given by peers how to make a better lesson plan and perform a more effective teaching. Hence, self and peer assessment is considered beneficial for preparing the real teaching practicum and future career development. However, there are some problems challenged them, such as feeling subjectivity in assessing both self or peers, embarrassed and less confidence, and time constraints to make evaluation and reflection in the classroom

  19. Using a Smartphone App and Coaching Group Sessions to Promote Residents' Reflection in the Workplace.

    Science.gov (United States)

    Könings, Karen D; van Berlo, Jean; Koopmans, Richard; Hoogland, Henk; Spanjers, Ingrid A E; ten Haaf, Jeroen A; van der Vleuten, Cees P M; van Merriënboer, Jeroen J G

    2016-03-01

    Reflecting on workplace-based experiences is necessary for professional development. However, residents need support to raise their awareness of valuable moments for learning and to thoughtfully analyze those learning moments afterwards. From October to December 2012, the authors held a multidisciplinary six-week postgraduate training module focused on general competencies. Residents were randomly assigned to one of four conditions with varying degrees of reflection support; they were offered (1) a smartphone app, (2) coaching group sessions, (3) a combination of both, or (4) neither type of support. The app allowed participants to capture in real time learning moments as a text note, audio recording, picture, or video. Coaching sessions held every two weeks aimed to deepen participants' reflection on captured learning moments. Questionnaire responses and reflection data were compared between conditions to assess the effects of the app and coaching sessions on intensity and frequency of reflection. Sixty-four residents participated. App users reflected more often, captured more learning moments, and reported greater learning progress than nonapp users. Participants who attended coaching sessions were more alert to learning moments and pursued more follow-up learning activities to improve on the general competencies. Those who received both types of support were most alert to these learning moments. A simple mobile app for capturing learning moments shows promise as a tool to support workplace-based learning, especially when combined with coaching sessions. Future research should evaluate these tools on a broader scale and in conjunction with residents' and students' personal digital portfolios.

  20. Thoughts on Reflection (Editorial

    Directory of Open Access Journals (Sweden)

    Denise Koufogiannakis

    2010-06-01

    Full Text Available There has been some acknowledgement in the published literature that reflection is a crucial element of the evidence based library and information practice (EBLIP model we have adopted (Booth 2004, 2006; Grant 2007; Helliwell 2007. As we work through a problem and try to incorporate the best available evidence into our decision making, reflection is required at several stages, including the very identification of the problem through to our assessment of the process itself and what we have learned in order to inform future practice. However, reflection and reflective writing have not fully been integrated into the process we espouse, and very little has been done to look more closely at this element of the model and how it can be integrated into professional learning.In a recently published research article, Sen (2010 confirms the relationship between reflection and several aspects of professional practice. These include critical review and decision making, two aspects that are tied closely to the evidence based process. Sen notes: Students were more likely to show evidence of learning, self‐development, the ability to review issues crucially, awareness of their own mental functions, ability to make decision [sic] and being empowered when they had mastered the art of reflective practice and the more deeply analytical reflective writing. (p.84 EBLIP (the journal tries to incorporate elements of reflection within the articles we publish. While we clearly believe in the need for our profession to do quality research and publish that research so that it can be accessible to practitioners, we also know that research cannot be looked at in isolation. Our evidence summaries are one way of reflecting critically on previously published research, and in the same vein, our classics bring older research studies back to the foreground. This work needs to continue to be discussed and looked at for its impact on our profession.More directly, the Using

  1. The Reflective Foundation

    DEFF Research Database (Denmark)

    Lunde Jørgensen, Ida

    Private foundations and cultural philanthropy by élites is viewed with increasing skepticism in recent years, begging the question of the extent to which foundations reflect on their role vis a vis wider societal norms. Through the prism of the New Carlsberg Foundation, financed by the brewery...... Carlsberg A/S, the paper seeks to elucidate the way in which one culturally significant foundation from Denmark has reflected on - and legitimated - its work and investments at critical moments in the past decades. The paper indicates a foundation with a high degree of reflection on the wider societal...

  2. Reflection-type hologram for atoms

    International Nuclear Information System (INIS)

    Shimizu, Fujio; Fujita, Jun-ichi

    2002-01-01

    A cold metastable neon atomic beam was manipulated with a reflective amplitude hologram that was encoded on a silicon surface. A black-and-white pattern of atoms was reconstructed on a microchannel plate detector. The hologram used the enhanced quantum reflection developed by authors and was made of a two-dimensional array of rectangular low and high reflective cells. The surface of the high reflective cell was composed of regularly spaced roof-shaped ridges, while the low reflective cell was simply a flat surface. The hologram was the first demonstration of reflective atom-optical elements that used universal interaction between a neutral atom and solid surface

  3. Effects of psychological therapies in randomized trials and practice-based studies.

    Science.gov (United States)

    Barkham, Michael; Stiles, William B; Connell, Janice; Twigg, Elspeth; Leach, Chris; Lucock, Mike; Mellor-Clark, John; Bower, Peter; King, Michael; Shapiro, David A; Hardy, Gillian E; Greenberg, Leslie; Angus, Lynne

    2008-11-01

    Randomized trials of the effects of psychological therapies seek internal validity via homogeneous samples and standardized treatment protocols. In contrast, practice-based studies aim for clinical realism and external validity via heterogeneous samples of clients treated under routine practice conditions. We compared indices of treatment effects in these two types of studies. Using published transformation formulas, the Beck Depression Inventory (BDI) scores from five randomized trials of depression (N = 477 clients) were transformed into Clinical Outcomes in Routine Evaluation-Outcome Measure (CORE-OM) scores and compared with CORE-OM data collected in four practice-based studies (N = 4,196 clients). Conversely, the practice-based studies' CORE-OM scores were transformed into BDI scores and compared with randomized trial data. Randomized trials showed a modest advantage over practice-based studies in amount of pre-post improvement. This difference was compressed or exaggerated depending on the direction of the transformation but averaged about 12%. There was a similarly sized advantage to randomized trials in rates of reliable and clinically significant improvement (RCSI). The largest difference was yielded by comparisons of effect sizes which suggested an advantage more than twice as large, reflecting narrower pre-treatment distributions in the randomized trials. Outcomes of completed treatments for depression in randomized trials appeared to be modestly greater than those in routine care settings. The size of the difference may be distorted depending on the method for calculating degree of change. Transforming BDI scores into CORE-OM scores and vice versa may be a preferable alternative to effect sizes for comparisons of studies using these measures.

  4. Reflective journal writing: how it promotes reflective thinking in clinical nursing education: a students' perspective.

    Science.gov (United States)

    Kok, J; Chabeli, M M

    2002-08-01

    According to the outcomes-based education and training system of education (OBET) in the country and the South African Nursing Council, education should focus on "creating" reflective learners and practitioners. This article seeks to determine the effectiveness of reflective journal writing in promoting the reflective thinking of learners in clinical nursing education and to validate the guidelines described in a bigger study on how to facilitate reflective thinking using reflective journal writing. A qualitative, contextual, explorative, descriptive research design was used to determine the learners' perceptions on whether reflective journal writing did promote their higher-level thinking skills during the six-month placement in a psychiatric clinical practice using the reflective diaries. From a population of seventeen fourth-year students, six volunteered to participate in a focus group interview. The data was analysed by means of the descriptive method of open coding of Tesch (in Creswell, 1994:154-156). Positive and negative results from the perceptions of the participants and a literature review served as a basis for deducing and describing guidelines for the effective use of reflective journal writing in promoting reflective thinking in clinical nursing education. The positive perception was the development of problem-solving skills attained through reflection by using analytical critical thinking, synthesis and the evaluation of situations. Self-evaluation leading to intellectual growth and self-awareness indicated a positive perception. Negative perceptions were that reflective journal writing is time consuming, content based with a lack of clear expectations from the teacher, and distrust of students about the information written. Guba's model of ensuring trustworthiness in qualitative research as described in Krefting (1991:215-222) was employed. It is concluded that reflective journal writing in clinical nursing education does promote reflective

  5. Storage array reflection considerations

    International Nuclear Information System (INIS)

    Haire, M.J.; Jordan, W.C.; Taylor, R.G.

    1997-01-01

    The assumptions used for reflection conditions of single containers are fairly well established and consistently applied throughout the industry in nuclear criticality safety evaluations. Containers are usually considered to be either fully water reflected (i.e., surrounded by 6 to 12 in. of water) for safety calculations or reflected by 1 in. of water for nominal (structural material and air) conditions. Tables and figures are usually available for performing comparative evaluations of containers under various loading conditions. Reflection considerations used for evaluating the safety of storage arrays of fissile material are not as well established. When evaluating arrays, it has become more common for analysts to use calculations to demonstrate the safety of the array configuration. In performing these calculations, the analyst has considerable freedom concerning the assumptions made for modeling the reflection of the array. Considerations are given for the physical layout of the array with little or no discussion (or demonstration) of what conditions are bounded by the assumed reflection conditions. For example, an array may be generically evaluated by placing it in a corner of a room in which the opposing walls are far away. Typically, it is believed that complete flooding of the room is incredible, so the array is evaluated for various levels of water mist interspersed among array containers. This paper discusses some assumptions that are made regarding storage array reflection

  6. Three-dimensional distribution of random velocity inhomogeneities at the Nankai trough seismogenic zone

    Science.gov (United States)

    Takahashi, T.; Obana, K.; Yamamoto, Y.; Nakanishi, A.; Kaiho, Y.; Kodaira, S.; Kaneda, Y.

    2012-12-01

    The Nankai trough in southwestern Japan is a convergent margin where the Philippine sea plate is subducted beneath the Eurasian plate. There are major faults segments of huge earthquakes that are called Tokai, Tonankai and Nankai earthquakes. According to the earthquake occurrence history over the past hundreds years, we must expect various rupture patters such as simultaneous or nearly continuous ruptures of plural fault segments. Japan Agency for Marine-Earth Science and Technology (JAMSTEC) conducted seismic surveys at Nankai trough in order to clarify mutual relations between seismic structures and fault segments, as a part of "Research concerning Interaction Between the Tokai, Tonankai and Nankai Earthquakes" funded by Ministry of Education, Culture, Sports, Science and Technology, Japan. This study evaluated the spatial distribution of random velocity inhomogeneities from Hyuga-nada to Kii-channel by using velocity seismograms of small and moderate sized earthquakes. Random velocity inhomogeneities are estimated by the peak delay time analysis of S-wave envelopes (e.g., Takahashi et al. 2009). Peak delay time is defined as the time lag from the S-wave onset to its maximal amplitude arrival. This quantity mainly reflects the accumulated multiple forward scattering effect due to random inhomogeneities, and is quite insensitive to the inelastic attenuation. Peak delay times are measured from the rms envelopes of horizontal components at 4-8Hz, 8-16Hz and 16-32Hz. This study used the velocity seismograms that are recorded by 495 ocean bottom seismographs and 378 onshore seismic stations. Onshore stations are composed of the F-net and Hi-net stations that are maintained by National Research Institute for Earth Science and Disaster Prevention (NIED) of Japan. It is assumed that the random inhomogeneities are represented by the von Karman type PSDF. Preliminary result of inversion analysis shows that spectral gradient of PSDF (i.e., scale dependence of

  7. Impact of Sulphur Content on Coal Quality at Delta Plain Depositional Environment: Case study in Geramat District, Lahat Regency, South Sumatra

    Directory of Open Access Journals (Sweden)

    Siska Linda Sari

    2017-09-01

    Full Text Available The research was conducted in Geramat District of Lahat Regency, South Sumatra. An evaluation of the geological condition of the research area shown that the coal deposits were found in Muara Enim Formation as a coal-bearing formation. The method used was literature study, field observation and the laboratory work includes proximate and petrography analysis. The aim of this research is to determine the environmental condition of coal based on the change of total sulphur content and to know the relation between ash content to calorific value.  As the result of proximate analysis conducted on five samples of coal, the research area obtained total sulphur (0,21-1,54% adb, ash content (3,16 - 71,11% adb and gross calorific value (953 - 5676 cal/g. adb. Based on the result of maceral analysis showed the maceral percentage of coal in research area composed by vitrinite (77,8-87,4 %, liptinite (0,6 %, inertinite (8,0 – 17,6 % and mineral matter concentration in the form of pyrite (1,6-4,6 %. The average reflectance value of vitrinite (Rv of coal in the research area (0.54%. the results analysis shows that the coal in Muara Enim Formation on the research area is in the transitional lower delta plain depositional environment phase. Any changes in the sedimentary environment affected by sea water will be followed by changes in total sulphur and the higher ash content, on the contrary, the lower calorific value of the coal.

  8. Reflectance Modeling

    Science.gov (United States)

    Smith, J. A.; Cooper, K.; Randolph, M.

    1984-01-01

    A classical description of the one dimensional radiative transfer treatment of vegetation canopies was completed and the results were tested against measured prairie (blue grama) and agricultural canopies (soybean). Phase functions are calculated in terms of directly measurable biophysical characteristics of the canopy medium. While the phase functions tend to exhibit backscattering anisotropy, their exact behavior is somewhat more complex and wavelength dependent. A Monte Carlo model was developed that treats soil surfaces with large periodic variations in three dimensions. A photon-ray tracing technology is used. Currently, the rough soil surface is described by analytic functions and appropriate geometric calculations performed. A bidirectional reflectance distribution function is calculated and, hence, available for other atmospheric or canopy reflectance models as a lower boundary condition. This technique is used together with an adding model to calculate several cases where Lambertian leaves possessing anisotropic leaf angle distributions yield non-Lambertian reflectance; similar behavior is exhibited for simulated soil surfaces.

  9. The effect of self-distancing on adaptive versus maladaptive self-reflection in children.

    Science.gov (United States)

    Kross, Ethan; Duckworth, Angela; Ayduk, Ozlem; Tsukayama, Eli; Mischel, Walter

    2011-10-01

    Although children and adolescents vary in their chronic tendencies to adaptively versus maladaptively reflect over negative feelings, the psychological mechanisms underlying these different types of self-reflection among youngsters are unknown. We addressed this issue in the present research by examining the role that self-distancing plays in distinguishing adaptive versus maladaptive self-reflection among an ethnically and socioeconomically diverse sample of fifth-grade public schoolchildren. Children were randomly assigned to analyze their feelings surrounding a recent anger-related interpersonal experience from either a self-immersed or self-distanced perspective. They then rated their negative affect and described in writing the stream of thoughts they experienced when they analyzed their feelings. Children's stream-of-thought essays were content analyzed for the presence of recounting statements, reconstruing statements, and blame attributions. Path analyses indicated that children who analyzed their feelings from a self-distanced perspective focused significantly less on recounting the "hot," emotionally arousing features of their memory (i.e., what happened to me?) and relatively more on reconstruing their experience. This shift in thought content--less recounting and more reconstruing--led children in the self-distanced group to blame the other person involved in their recalled experience significantly less, which in turn led them to display significantly lower levels of emotional reactivity. These findings help delineate the psychological mechanisms that distinguish adaptive versus maladaptive forms of self-reflection over anger experiences in children. Their basic findings and clinical implications are discussed.

  10. [Intel random number generator-based true random number generator].

    Science.gov (United States)

    Huang, Feng; Shen, Hong

    2004-09-01

    To establish a true random number generator on the basis of certain Intel chips. The random numbers were acquired by programming using Microsoft Visual C++ 6.0 via register reading from the random number generator (RNG) unit of an Intel 815 chipset-based computer with Intel Security Driver (ISD). We tested the generator with 500 random numbers in NIST FIPS 140-1 and X(2) R-Squared test, and the result showed that the random number it generated satisfied the demand of independence and uniform distribution. We also compared the random numbers generated by Intel RNG-based true random number generator and those from the random number table statistically, by using the same amount of 7500 random numbers in the same value domain, which showed that the SD, SE and CV of Intel RNG-based random number generator were less than those of the random number table. The result of u test of two CVs revealed no significant difference between the two methods. Intel RNG-based random number generator can produce high-quality random numbers with good independence and uniform distribution, and solves some problems with random number table in acquisition of the random numbers.

  11. Reflection Revisited: The Class Collage

    Science.gov (United States)

    Sommers, Jeff

    2011-01-01

    Through the regular use of what Donald Schon has termed reflection-in-action and reflection-on-action, students can learn to improve their "reflection-in-presentation," in Kathleen Blake Yancey's term. Students are often asked to do this type of reflection-in-presentation as a capstone to first-year or basic writing courses. However, a number of…

  12. Effect of organic-matter type and thermal maturity on methane adsorption in shale-gas systems

    Science.gov (United States)

    Zhang, Tongwei; Ellis, Geoffrey S.; Ruppel, Stephen C.; Milliken, Kitty; Yang, Rongsheng

    2012-01-01

    A series of methane (CH4) adsorption experiments on bulk organic rich shales and their isolated kerogens were conducted at 35 °C, 50 °C and 65 °C and CH4 pressure of up to 15 MPa under dry conditions. Samples from the Eocene Green River Formation, Devonian–Mississippian Woodford Shale and Upper Cretaceous Cameo coal were studied to examine how differences in organic matter type affect natural gas adsorption. Vitrinite reflectance values of these samples ranged from 0.56–0.58 %Ro. In addition, thermal maturity effects were determined on three Mississippian Barnett Shale samples with measured vitrinite reflectance values of 0.58, 0.81 and 2.01 %Ro. For all bulk and isolated kerogen samples, the total amount of methane adsorbed was directly proportional to the total organic carbon (TOC) content of the sample and the average maximum amount of gas sorption was 1.36 mmol of methane per gram of TOC. These results indicate that sorption on organic matter plays a critical role in shale-gas storage. Under the experimental conditions, differences in thermal maturity showed no significant effect on the total amount of gas sorbed. Experimental sorption isotherms could be fitted with good accuracy by the Langmuir function by adjusting the Langmuir pressure (PL) and maximum sorption capacity (Γmax). The lowest maturity sample (%Ro = 0.56) displayed a Langmuir pressure (PL) of 5.15 MPa, significantly larger than the 2.33 MPa observed for the highest maturity (%Ro > 2.01) sample at 50 °C. The value of the Langmuir pressure (PL) changes with kerogen type in the following sequence: type I > type II > type III. The thermodynamic parameters of CH4 adsorption on organic rich shales were determined based on the experimental CH4 isotherms. For the adsorption of CH4 on organic rich shales and their isolated kerogen, the heat of adsorption (q) and the standard entropy (Δs0) range from 7.3–28.0 kJ/mol and from −36.2 to −92.2 J/mol/K, respectively.

  13. Assessment of Thermal Maturity Trends in Devonian–Mississippian Source Rocks Using Raman Spectroscopy: Limitations of Peak-Fitting Method

    Energy Technology Data Exchange (ETDEWEB)

    Lupoi, Jason S., E-mail: jlupoi@rjlg.com; Fritz, Luke P. [RJ Lee Group, Inc., Monroeville, PA (United States); Parris, Thomas M. [Kentucky Geological Survey, University of Kentucky, Lexington, KY (United States); Hackley, Paul C. [UniversityS. Geological Survey, Reston, VA (United States); Solotky, Logan [RJ Lee Group, Inc., Monroeville, PA (United States); Eble, Cortland F. [Kentucky Geological Survey, University of Kentucky, Lexington, KY (United States); Schlaegle, Steve [RJ Lee Group, Inc., Monroeville, PA (United States)

    2017-09-27

    The thermal maturity of shale is often measured by vitrinite reflectance (VRo). VRo measurements for the Devonian–Mississippian black shale source rocks evaluated herein predicted thermal immaturity in areas where associated reservoir rocks are oil-producing. This limitation of the VRo method led to the current evaluation of Raman spectroscopy as a suitable alternative for developing correlations between thermal maturity and Raman spectra. In this study, Raman spectra of Devonian–Mississippian black shale source rocks were regressed against measured VRo or sample-depth. Attempts were made to develop quantitative correlations of thermal maturity. Using sample-depth as a proxy for thermal maturity is not without limitations as thermal maturity as a function of depth depends on thermal gradient, which can vary through time, subsidence rate, uplift, lack of uplift, and faulting. Correlations between Raman data and vitrinite reflectance or sample-depth were quantified by peak-fitting the spectra. Various peak-fitting procedures were evaluated to determine the effects of the number of peaks and maximum peak widths on correlations between spectral metrics and thermal maturity. Correlations between D-frequency, G-band full width at half maximum (FWHM), and band separation between the G- and D-peaks and thermal maturity provided some degree of linearity throughout most peak-fitting assessments; however, these correlations and those calculated from the G-frequency, D/G FWHM ratio, and D/G peak area ratio also revealed a strong dependence on peak-fitting processes. This dependency on spectral analysis techniques raises questions about the validity of peak-fitting, particularly given the amount of subjective analyst involvement necessary to reconstruct spectra. This research shows how user interpretation and extrapolation affected the comparability of different samples, the accuracy of generated trends, and therefore, the potential of the Raman spectral method to become an

  14. A Paleomagnetic and Diagenetic Study of the Woodford Shale, Oklahoma, U.S.A.: The Timing of Hydrothermal Alteration

    Science.gov (United States)

    Roberts, J.; Elmore, R. D.

    2017-12-01

    An oriented Woodford Shale core from the Ardmore Basin near the Ouachita thrust zone (Core B) was sampled to identify diagenetic events and interpret their origin, and to test if a magnetization was present that can be used to date the altering event(s). The shale is extensively altered, exhibiting a complex paragenesis with multiple fractures and brecciated intervals. Multiple hydrothermal minerals, including biotite, magnesite, norsethite, witherite, gorceixite, potassium feldspar, sphalerite, chalcopyrite, and saddle dolomite, are present in and around fractures and in the matrix. Vitrinite and bitumen reflectance measurements indicate VRo values of 1.82% ( 230°C). Two other Woodford Shale cores (A and C) from the Anadarko Basin also contain hydrothermal minerals. Vitrinite and bitumen reflectance data reveal trends between thermal maturity and the level of hydrothermal alteration, with Core A (0.80% VRo ( 125°C) displaying the lowest alteration, and Core C ( 1.5% VRo ( 210°C) displaying intermediate alteration compared to core B. Paleomagnetic analysis of Core B reveals the presence of a characteristic remanent magnetization (ChRM) with south-southeasterly declinations and shallow inclinations that is unblocked by 450°C and is interpreted to reside in magnetite. This ChRM is interpreted to be either a chemical remanent magnetization (CRM) or a thermochemical remanent magnetization (TCRM) acquired during the Late Permian based on the pole position. The presence of specimens with the CRM/TCRM in altered rock and high thermal maturities suggests that this CRM/TCRM originated from alteration by hydrothermal fluids. These results suggest that the Woodford Shale evolved into an open diagenetic system. In addition to causing heightened thermal maturities, these hydrothermal fluids both increased porosity through dissolution and decreased porosity through precipitation of minerals. The Late Permian timing agrees with the dating of hydrothermal alteration found

  15. Assessment of Thermal Maturity Trends in Devonian–Mississippian Source Rocks Using Raman Spectroscopy: Limitations of Peak-Fitting Method

    International Nuclear Information System (INIS)

    Lupoi, Jason S.; Fritz, Luke P.; Parris, Thomas M.; Hackley, Paul C.; Solotky, Logan; Eble, Cortland F.; Schlaegle, Steve

    2017-01-01

    The thermal maturity of shale is often measured by vitrinite reflectance (VRo). VRo measurements for the Devonian–Mississippian black shale source rocks evaluated herein predicted thermal immaturity in areas where associated reservoir rocks are oil-producing. This limitation of the VRo method led to the current evaluation of Raman spectroscopy as a suitable alternative for developing correlations between thermal maturity and Raman spectra. In this study, Raman spectra of Devonian–Mississippian black shale source rocks were regressed against measured VRo or sample-depth. Attempts were made to develop quantitative correlations of thermal maturity. Using sample-depth as a proxy for thermal maturity is not without limitations as thermal maturity as a function of depth depends on thermal gradient, which can vary through time, subsidence rate, uplift, lack of uplift, and faulting. Correlations between Raman data and vitrinite reflectance or sample-depth were quantified by peak-fitting the spectra. Various peak-fitting procedures were evaluated to determine the effects of the number of peaks and maximum peak widths on correlations between spectral metrics and thermal maturity. Correlations between D-frequency, G-band full width at half maximum (FWHM), and band separation between the G- and D-peaks and thermal maturity provided some degree of linearity throughout most peak-fitting assessments; however, these correlations and those calculated from the G-frequency, D/G FWHM ratio, and D/G peak area ratio also revealed a strong dependence on peak-fitting processes. This dependency on spectral analysis techniques raises questions about the validity of peak-fitting, particularly given the amount of subjective analyst involvement necessary to reconstruct spectra. This research shows how user interpretation and extrapolation affected the comparability of different samples, the accuracy of generated trends, and therefore, the potential of the Raman spectral method to become an

  16. Assessment of Thermal Maturity Trends in Devonian–Mississippian Source Rocks Using Raman Spectroscopy: Limitations of Peak-Fitting Method

    Directory of Open Access Journals (Sweden)

    Jason S. Lupoi

    2017-09-01

    Full Text Available The thermal maturity of shale is often measured by vitrinite reflectance (VRo. VRo measurements for the Devonian–Mississippian black shale source rocks evaluated herein predicted thermal immaturity in areas where associated reservoir rocks are oil-producing. This limitation of the VRo method led to the current evaluation of Raman spectroscopy as a suitable alternative for developing correlations between thermal maturity and Raman spectra. In this study, Raman spectra of Devonian–Mississippian black shale source rocks were regressed against measured VRo or sample-depth. Attempts were made to develop quantitative correlations of thermal maturity. Using sample-depth as a proxy for thermal maturity is not without limitations as thermal maturity as a function of depth depends on thermal gradient, which can vary through time, subsidence rate, uplift, lack of uplift, and faulting. Correlations between Raman data and vitrinite reflectance or sample-depth were quantified by peak-fitting the spectra. Various peak-fitting procedures were evaluated to determine the effects of the number of peaks and maximum peak widths on correlations between spectral metrics and thermal maturity. Correlations between D-frequency, G-band full width at half maximum (FWHM, and band separation between the G- and D-peaks and thermal maturity provided some degree of linearity throughout most peak-fitting assessments; however, these correlations and those calculated from the G-frequency, D/G FWHM ratio, and D/G peak area ratio also revealed a strong dependence on peak-fitting processes. This dependency on spectral analysis techniques raises questions about the validity of peak-fitting, particularly given the amount of subjective analyst involvement necessary to reconstruct spectra. This research shows how user interpretation and extrapolation affected the comparability of different samples, the accuracy of generated trends, and therefore, the potential of the Raman spectral

  17. Control of back surface reflectance from aluminum alloyed contacts on silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Cudzinovic, M.; Sopori, B. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    A process for forming highly reflective aluminum back contacts with low contact resistance to silicon solar cells is described. By controlling the process conditions, it is possible to vary the silicon/aluminum interface from a specular to a diffuse reflector while maintaining a high interface reflectance. The specular interface is found to be a uniform silicon/aluminum alloy layer a few angstroms thick that has epitaxially regrown on the silicon. The diffuse interface consists of randomly distributed (111) pyramids produced by crystallographic out-diffusion of the bulk silicon. The light trapping ability of the diffuse contact is found to be close to the theoretical limit. Both types of contacts are found to have specific contact resistivities of 10{sup {minus}5} {Omega}-cm{sup 2}. The process for forming the contacts involves illuminating the devices with tungsten halogen lamps. The process is rapid (under 100 s) and low temperature (peak temperature < 580{degrees}C), making it favorable for commercial solar cell fabrication.

  18. Randomization tests

    CERN Document Server

    Edgington, Eugene

    2007-01-01

    Statistical Tests That Do Not Require Random Sampling Randomization Tests Numerical Examples Randomization Tests and Nonrandom Samples The Prevalence of Nonrandom Samples in Experiments The Irrelevance of Random Samples for the Typical Experiment Generalizing from Nonrandom Samples Intelligibility Respect for the Validity of Randomization Tests Versatility Practicality Precursors of Randomization Tests Other Applications of Permutation Tests Questions and Exercises Notes References Randomized Experiments Unique Benefits of Experiments Experimentation without Mani

  19. Reflection: A Socratic approach.

    Science.gov (United States)

    Van Seggelen-Damen, Inge C M; Van Hezewijk, René; Helsdingen, Anne S; Wopereis, Iwan G J H

    2017-12-01

    Reflection is a fuzzy concept. In this article we reveal the paradoxes involved in studying the nature of reflection. Whereas some scholars emphasize its discursive nature, we go further and underline its resemblance to the self-biased dialogue Socrates had with the slave in Plato's Meno . The individual and internal nature of the reflection process creates difficulty for studying it validly and reliably. We focus on methodological issues and use Hans Linschoten's view of coupled systems to identify, analyze, and interpret empirical research on reflection. We argue that researchers and research participants can take on roles in several possible system couplings. Depending on who controls the manipulation of the stimulus, who controls the measuring instrument, who interprets the measurement and the response, different types of research questions can be answered. We conclude that reflection may be validly studied by combining different couplings of experimenter, manipulation, stimulus, participant, measurement, and response.

  20. Modeling and optimizing of the random atomic spin gyroscope drift based on the atomic spin gyroscope

    Energy Technology Data Exchange (ETDEWEB)

    Quan, Wei; Lv, Lin, E-mail: lvlinlch1990@163.com; Liu, Baiqi [School of Instrument Science and Opto-Electronics Engineering, Beihang University, Beijing 100191 (China)

    2014-11-15

    In order to improve the atom spin gyroscope's operational accuracy and compensate the random error caused by the nonlinear and weak-stability characteristic of the random atomic spin gyroscope (ASG) drift, the hybrid random drift error model based on autoregressive (AR) and genetic programming (GP) + genetic algorithm (GA) technique is established. The time series of random ASG drift is taken as the study object. The time series of random ASG drift is acquired by analyzing and preprocessing the measured data of ASG. The linear section model is established based on AR technique. After that, the nonlinear section model is built based on GP technique and GA is used to optimize the coefficients of the mathematic expression acquired by GP in order to obtain a more accurate model. The simulation result indicates that this hybrid model can effectively reflect the characteristics of the ASG's random drift. The square error of the ASG's random drift is reduced by 92.40%. Comparing with the AR technique and the GP + GA technique, the random drift is reduced by 9.34% and 5.06%, respectively. The hybrid modeling method can effectively compensate the ASG's random drift and improve the stability of the system.

  1. Re-thinking reflection in supervision

    DEFF Research Database (Denmark)

    Lystbæk, Christian Tang

    The paper presents a socio-cultural perspective on supervision in professional education, which challenges the current reflective paradigm and move the debate on reflection in supervision in professional education and learning towards a recognition of context, power dynamics and ideological...... of reflective practice has been formalized by regulatory bodies as a way to develop the professionalism of both individual professional practitioners as students through continuing professional developmental processes. Consequently, reflection is often used as a `tool´ for personal and professional development...... al., 2010). This conceptual paper presents a critical, socio-cultural perspective on the current paradigm or dogma of reflective practice within supervision in professional education and learning. The purpose I to challenge the dogma and critically to analyze and move the debate on reflection...

  2. Demystifying the reflective clinical journal

    International Nuclear Information System (INIS)

    Milinkovic, Danielle; Field, Nikki

    2005-01-01

    Student learning on clinical placement is a complex issue and cannot be defined solely by just doing things. Reflection during clinical practice is essential if the student is going to learn from the experience. Therefore it is important for educators to include as part of clinical education programs learning strategies that encourage reflection. The reflective clinical journal is an educational tool that is employed by the School of Medical Radiation Sciences at the University of Sydney to encourage reflection of undergraduate radiation therapy students whilst on clinical placement. This discussion paper explores the key concepts of reflection and the reflective clinical journal. Due to the paucity of information about this issue in radiation therapy the literature reviewed is from across all areas of the health sciences

  3. 'Combined reflectance stratigraphy' - subdivision of loess successions by diffuse reflectance spectrometry (DRS)

    Science.gov (United States)

    Szeberényi, Jozsef; Bradak-Hayashi, Balázs; Kiss, Klaudia; Kovács, József; Varga, György; Balázs, Réka; Szalai, Zoltán; Viczián, István

    2016-04-01

    The different varieties of loess (and intercalated paleosol layers) together constitute one of the most widespread terrestrial sediments, which was deposited, altered, and redeposited in the course of the changing climatic conditions of the Pleistocene. To reveal more information about Pleistocene climate cycles and/or environments the detailed lithostratigraphical subdivision and classification of the loess variations and paleosols are necessary. Beside the numerous method such as various field measurements, semi-quantitative tests and laboratory investigations, diffuse reflectance spectroscopy (DRS) is one of the well applied method on loess/paleosol sequences. Generally, DRS has been used to separate the detrital and pedogenic mineral component of the loess sections by the hematite/goethite ratio. DRS also has been applied as a joint method of various environmental magnetic investigations such as magnetic susceptibility- and isothermal remanent magnetization measurements. In our study the so-called "combined reflectance stratigraphy method" were developed. At First, complex mathematical method was applied to compare the results of the spectral reflectance measurements. One of the most preferred multivariate methods is cluster analysis. Its scope is to group and compare the loess variations and paleosol based on the similarity and common properties of their reflectance curves. In the Second, beside the basic subdivision of the profiles by the different reflectance curves of the layers, the most characteristic wavelength section of the reflectance curve was determined. This sections played the most important role during the classification of the different materials of the section. The reflectance value of individual samples, belonged to the characteristic wavelength were depicted in the function of depth and well correlated with other proxies like grain size distribution and magnetic susceptibility data. The results of the correlation showed the significance of

  4. Developing Self-Regulation by Using Reflective Support in a Video-Digital Microteaching Environment

    Directory of Open Access Journals (Sweden)

    Zehavit Kohen

    2012-01-01

    Full Text Available Recent research efforts have established that self-regulated learning (SRL is necessary for teachers to attain successful professional development. Our study addresses two central questions: under what conditions in preservice teachers' education can SRL processes be enhanced to the optimum level, and how can we assess these processes? The participants of the study were ninety-seven preservice teachers, who were engaged in real-time teaching in a video-digital Microteaching environment. Each participant was randomly assigned to one of two groups: reflective support (RS for SRL or no support (NS for SRL. Participants in the RS group were explicitly exposed to SRL aspects and were directed to address these aspects in their reflective discussions of the teaching experience. The SRL process was measured as an online event during real-time teaching exercises, based on a coding scheme developed for this study to identify and assess the SRL skills by two major aspects: metacognition (planning, information management, monitoring, debugging, and evaluating and motivation (interest and value, self-efficacy, and teaching anxiety. Results indicate that the RS group outperformed the NS group in all SRL measures. Implications for reflective support for SRL and event measures of real-time observations of preservice teachers' SRL are discussed.

  5. Reflective optics

    CERN Document Server

    Korsch, Dietrich

    1991-01-01

    This is the first book dedicated exclusively to all-reflective imaging systems. It is a teaching tool as well as a practical design tool for anyone who specializes in optics, particularly for those interested in telescopes, infrared, and grazing-incidence systems. The first part of the book describes a unified geometric optical theory of all-reflective imaging systems (from near-normal to grazing incidence) developed from basic principles. The second part discusses correction methods and a multitude of closed-form solutions of well-corrected systems, supplemented with many conventional and unc

  6. A novel procedure to detect low molecular weight compounds released by alkaline ester cleavage from low maturity coals to assess its feedstock for deep microbial life

    DEFF Research Database (Denmark)

    Glombitza, Clemens; Mangelsdorf, Kai; Horsfield, Brian

    2009-01-01

    and South Island of New Zealand (NZ) were examined to assess the amount of bound LMW organic acids. Formate, acetate and oxalate were detected in significant amounts whereas the amounts of these compounds decrease with increasing maturity of the coal sample. This decrease of LMW organic acids mainly...... for the investigation of low molecular weight (LMW) organic acids linked to the kerogen matrix is presented. These LMW organic acids form a potential feedstock for deep microbial populations. Twelve coal samples of different maturity (vitrinite reflectance (R0) of 0.28–0.80%) from several coal mines on the North...... and generation rates of LMW organic acids indicate that the NZ coals investigated exhibit the potential to feed deep terrestrial microbial life with appropriate substrates over geological time spans....

  7. Random walks in nanotube composites: Improved algorithms and the role of thermal boundary resistance

    International Nuclear Information System (INIS)

    Duong, Hai M.; Papavassiliou, Dimitrios V.; Lee, Lloyd L.; Mullen, Kieran J.

    2005-01-01

    Random walk simulations of thermal walkers are used to study the effect of interfacial resistance on heat flow in randomly dispersed carbon nanotube composites. The adopted algorithm effectively makes the thermal conductivity of the nanotubes themselves infinite. The probability that a walker colliding with a matrix-nanotube interface reflects back into the matrix phase or crosses into the carbon nanotube phase is determined by the thermal boundary (Kapitza) resistance. The use of 'cold' and 'hot' walkers produces a steady state temperature profile that allows accurate determination of the thermal conductivity. The effects of the carbon nanotube orientation, aspect ratio, volume fraction, and Kapitza resistance on the composite effective conductivity are quantified

  8. Reflective Practice for Psychology Students: The Use of Reflective Journal Feedback in Higher Education

    Science.gov (United States)

    Bruno, Andreina; Dell'Aversana, Giuseppina

    2017-01-01

    Reflective journals have emerged as an effective means of monitoring and developing reflective practice in higher education, as part of a wider metacognitive strategy to transform traditional learning approaches. In addition, assessment procedures of reflective journals appear to be an important factor in enhancing commitment to learning and…

  9. Guided and Unguided Student Reflections

    OpenAIRE

    Matheson, Amanda; Wood, Laura; Franklin, Scott V.

    2017-01-01

    Self-reflection is important metacognitive skill, enabling students to build coherence into their learning and embed content in a broader context. While various pedagogical techniques exist to encourage student reflection, little research has examined the differences between formally guided, partially guided and unguided reflections. This study focuses on student responses to online Guided Reflection Forms (GRFs) from students in a first-semester non-physics class and, separately, a sophomore...

  10. Effectuation And Reflection-In-Action

    DEFF Research Database (Denmark)

    Gertsen, Frank; Lervang, Johan-Ulrik; Maack, Karl

    2013-01-01

    Our main aim is to facilitate a reflective methodology for MSc thesis students in practical entrepreneurship that draws on the ideas of ‘reflection-in-action’ while simultaneously making use of the effectuation logics.......Our main aim is to facilitate a reflective methodology for MSc thesis students in practical entrepreneurship that draws on the ideas of ‘reflection-in-action’ while simultaneously making use of the effectuation logics....

  11. Creation, Identity and Reflection

    Directory of Open Access Journals (Sweden)

    Alina Beatrice Cheşcă

    2015-05-01

    Full Text Available The paper “Creation, Identity and Reflection” approaches the identification in the “mirror” of reality with creation, in other words seeking the authors’ identity in the reflected images. Reflection means attempting to find oneself, the mirror being the main principle of creation. Many characters become interesting only when they step into the world beyond the mirror, when their faces are doubled by the other self or when their selves are returned by other characters. The narcissistic concept of the mirror, i.e. the reflection in the mirror and the representation of the mirror itself, is a recurrent one in literature, but the reflection of the self which is not the self (as it is a reflection does not necessarily appear in a mirror or in a photograph or portrait. Sometimes, the not-self is returned to the self by another person or character. As far as Oscar Wilde’s theories are concerned, the main idea is that people are interesting for their masks, not for their inner nature. What Wilde calls “inner nature” is the characters’ un-reflected self and the mask is the reflection, the self in the mirror. Some characters’ relationships develop within a fiction that they dramatically try to preserve and protect with the risk of suffering. They refuse to take off the masks which define them in the others’ minds and hearts; the narcissistic individuals (both artists and characters seek and love their own image which they project upon facts, thus creating a fictive realm.

  12. Methods for quantitative infrared directional-hemispherical and diffuse reflectance measurements using an FTIR and a commercial integrating sphere

    Energy Technology Data Exchange (ETDEWEB)

    Blake, Thomas A.; Johnson, Timothy J.; Tonkyn, Russell G.; Forland, Brenda M.; Myers, Tanya L.; Brauer, Carolyn S.; Su, Yin-Fong; Bernacki, Bruce E.; Hanssen, Leonard; Gonzalez, Gerardo

    2018-01-01

    Infrared integrating sphere measurements of solid samples are important in providing reference data for contact, standoff and remote sensing applications. At the Pacific Northwest National Laboratory (PNNL) we have developed protocols to measure both the directional-hemispherical ( and diffuse (d) reflectances of powders, liquids, and disks of powders and solid materials using a commercially available, matte gold-coated integrating sphere and Fourier transform infrared spectrometer. Detailed descriptions of the sphere alignment and its use for making these reflectance measurements are given. Diffuse reflectance values were found to be dependent on the bidirectional reflection distribution function (BRDF) of the sample and the solid angle intercepted by the sphere’s specular exclusion port. To determine how well the sphere and protocols produce quantitative reflectance data, measurements were made of three diffuse and two specular standards prepared by the National institute of Standards and Technology (NIST, USA), LabSphere Infragold and Spectralon standards, hand-loaded sulfur and talc powder samples, and water. The five NIST standards behaved as expected: the three diffuse standards had a high degree of “diffuseness,” d/ = D > 0.9, whereas the two specular standards had D ≤ 0.03. The average absolute differences between the NIST and PNNL measurements of the NIST standards for both directional-hemispherical and diffuse reflectances are on the order of 0.01 reflectance units. Other quantitative differences between the PNNL-measured and calibration (where available) or literature reflectance values for these standards and materials are given and the possible origins of discrepancies are discussed. Random uncertainties and estimates of systematic uncertainties are presented. Corrections necessary to provide better agreement between the PNNL reflectance values as measured for the NIST standards and the NIST reflectance values for these same standards are also

  13. Random a-adic groups and random net fractals

    Energy Technology Data Exchange (ETDEWEB)

    Li Yin [Department of Mathematics, Nanjing University, Nanjing 210093 (China)], E-mail: Lyjerry7788@hotmail.com; Su Weiyi [Department of Mathematics, Nanjing University, Nanjing 210093 (China)], E-mail: suqiu@nju.edu.cn

    2008-08-15

    Based on random a-adic groups, this paper investigates the relationship between the existence conditions of a positive flow in a random network and the estimation of the Hausdorff dimension of a proper random net fractal. Subsequently we describe some particular random fractals for which our results can be applied. Finally the Mauldin and Williams theorem is shown to be very important example for a random Cantor set with application in physics as shown in E-infinity theory.

  14. Students’ Learning through Reflective Journaling

    OpenAIRE

    Alvyda Liuolienė; Regina Metiūnienė

    2011-01-01

    The aim of the article is to get acquainted with the types of journals used in education to help students to learn. The paper presents some ways of fostering student’s learning through reflective journaling. It also describes the key aspects of a new method ARRIVE cycle in connection with teachers preparation to use reflective journals in a classroom. The article also presents self-assessment in reflective journaling and students’ need to self-evaluate their learning process. Reflective journ...

  15. Selectively reflective transparent sheets

    Science.gov (United States)

    Waché, Rémi; Florescu, Marian; Sweeney, Stephen J.; Clowes, Steven K.

    2015-08-01

    We investigate the possibility to selectively reflect certain wavelengths while maintaining the optical properties on other spectral ranges. This is of particular interest for transparent materials, which for specific applications may require high reflectivity at pre-determined frequencies. Although there exist currently techniques such as coatings to produce selective reflection, this work focuses on new approaches for mass production of polyethylene sheets which incorporate either additives or surface patterning for selective reflection between 8 to 13 μ m. Typical additives used to produce a greenhouse effect in plastics include particles such as clays, silica or hydroxide materials. However, the absorption of thermal radiation is less efficient than the decrease of emissivity as it can be compared with the inclusion of Lambertian materials. Photonic band gap engineering by the periodic structuring of metamaterials is known in nature for producing the vivid bright colors in certain organisms via strong wavelength-selective reflection. Research to artificially engineer such structures has mainly focused on wavelengths in the visible and near infrared. However few studies to date have been carried out to investigate the properties of metastructures in the mid infrared range even though the patterning of microstructure is easier to achieve. We present preliminary results on the diffuse reflectivity using FDTD simulations and analyze the technical feasibility of these approaches.

  16. Non-compact random generalized games and random quasi-variational inequalities

    OpenAIRE

    Yuan, Xian-Zhi

    1994-01-01

    In this paper, existence theorems of random maximal elements, random equilibria for the random one-person game and random generalized game with a countable number of players are given as applications of random fixed point theorems. By employing existence theorems of random generalized games, we deduce the existence of solutions for non-compact random quasi-variational inequalities. These in turn are used to establish several existence theorems of noncompact generalized random ...

  17. Perioperative self-reflection among surgical residents.

    Science.gov (United States)

    Peshkepija, Andi N; Basson, Marc D; Davis, Alan T; Ali, Muhammad; Haan, Pam S; Gupta, Rama N; Hardaway, John C; Nebeker, Cody A; McLeod, Michael K; Osmer, Robert L; Anderson, Cheryl I

    2017-09-01

    We studied prevalence and predictors of meaningful self-reflection among surgical residents and with prompting/structured interventions, sought to improve/sustain resident skills. Residents from six programs recorded 1032 narrative self-reflective comments (120 residents), using a web-based platform. If residents identified something learned or to be improved, self-reflection was deemed meaningful. Independent variables PGY level, resident/surgeon gender, study site/Phase1: July2014-August2015 vs. Phase2: September2015-September2016) were analyzed. Meaningful self-reflection was documented in 40.6% (419/1032) of entries. PGY5's meaningfully self-reflected less than PGY1-4's, 26.1% vs. 49.6% (p = 0.002). In multivariate analysis, resident narratives during Phase 2 were 4.7 times more likely to engage in meaningful self-reflection compared to Phase1 entries (p self-reflection, compared to Phase1. Surgical residents uncommonly practice meaningful self-reflection, even when prompted, and PGY5/chief residents reflect less than more junior residents. Substantial/sustained improvements in resident self-reflection can occur with both training and interventions. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. On the reflection point where light reflects to a known destination on quadratic surfaces.

    Science.gov (United States)

    Gonçalves, Nuno

    2010-01-15

    We address the problem of determining the reflection point on a specular surface where a light ray that travels from a source to a target is reflected. The specular surfaces considered are those expressed by a quadratic equation. So far, there is no closed form explicit equation for the general solution of this determination of the reflection point, and the usual approach is to use the Snell law or the Fermat principle whose equations are derived in multidimensional nonlinear minimizations. We prove in this Letter that one can impose a set of three restrictions to the reflection point that can impose a set of three restrictions that culminates in a very elegant formalism of searching the reflection point in a unidimensional curve in space. This curve is the intersection of two quadratic equations. Some applications of this framework are also discussed.

  19. Reflection in Russian Educational Psychology.

    Science.gov (United States)

    Nelissen, Jo M. C.; Tomic, Welko

    This paper discusses the cultural-historical school founded by Vygotsky, Luria, and Leontiev as the theoretical background of Russian educational psychologists who have been studying how children learn to reflect. Two approaches to reflection are examined within the cultural-historical tradition: first, reflection--like other higher psychological…

  20. How random are random numbers generated using photons?

    International Nuclear Information System (INIS)

    Solis, Aldo; Angulo Martínez, Alí M; Ramírez Alarcón, Roberto; Cruz Ramírez, Hector; U’Ren, Alfred B; Hirsch, Jorge G

    2015-01-01

    Randomness is fundamental in quantum theory, with many philosophical and practical implications. In this paper we discuss the concept of algorithmic randomness, which provides a quantitative method to assess the Borel normality of a given sequence of numbers, a necessary condition for it to be considered random. We use Borel normality as a tool to investigate the randomness of ten sequences of bits generated from the differences between detection times of photon pairs generated by spontaneous parametric downconversion. These sequences are shown to fulfil the randomness criteria without difficulties. As deviations from Borel normality for photon-generated random number sequences have been reported in previous work, a strategy to understand these diverging findings is outlined. (paper)

  1. Reflection during Portfolio-Based Conversations

    Science.gov (United States)

    Oosterbaan, Anne E.; van der Schaaf, Marieke F.; Baartman, Liesbeth K. J.; Stokking, Karel M.

    2010-01-01

    This study aims to explore the relationship between the occurrence of reflection (and non-reflection) and thinking activities (e.g., orientating, selecting, analysing) during portfolio-based conversations. Analysis of 21 transcripts of portfolio-based conversations revealed that 20% of the segments were made up of reflection (content reflection…

  2. Exploration of a Polarized Surface Bidirectional Reflectance Model Using the Ground-Based Multiangle SpectroPolarimetric Imager

    Directory of Open Access Journals (Sweden)

    David J. Diner

    2012-12-01

    Full Text Available Accurate characterization of surface reflection is essential for retrieval of aerosols using downward-looking remote sensors. In this paper, observations from the Ground-based Multiangle SpectroPolarimetric Imager (GroundMSPI are used to evaluate a surface polarized bidirectional reflectance distribution function (PBRDF model. GroundMSPI is an eight-band spectropolarimetric camera mounted on a rotating gimbal to acquire pushbroom imagery of outdoor landscapes. The camera uses a very accurate photoelastic-modulator-based polarimetric imaging technique to acquire Stokes vector measurements in three of the instrument’s bands (470, 660, and 865 nm. A description of the instrument is presented, and observations of selected targets within a scene acquired on 6 January 2010 are analyzed. Data collected during the course of the day as the Sun moved across the sky provided a range of illumination geometries that facilitated evaluation of the surface model, which is comprised of a volumetric reflection term represented by the modified Rahman-Pinty-Verstraete function plus a specular reflection term generated by a randomly oriented array of Fresnel-reflecting microfacets. While the model is fairly successful in predicting the polarized reflection from two grass targets in the scene, it does a poorer job for two manmade targets (a parking lot and a truck roof, possibly due to their greater degree of geometric organization. Several empirical adjustments to the model are explored and lead to improved fits to the data. For all targets, the data support the notion of spectral invariance in the angular shape of the unpolarized and polarized surface reflection. As noted by others, this behavior provides valuable constraints on the aerosol retrieval problem, and highlights the importance of multiangle observations.

  3. Preoperative warm-up the key to improved resident technique: a randomized study.

    Science.gov (United States)

    Moran-Atkin, Erin; Abdalla, Gamal; Chen, Grace; Magnuson, Thomas H; Lidor, Anne O; Schweitzer, Michael A; Steele, Kimberley E

    2015-05-01

    The ACGME has required that a skills lab be incorporated into the surgical residency curriculum. While the value of warm-up is generally accepted in other areas requiring complex motor skills, there is little evidence to support the benefits of warm-up prior to performing surgery. We are conducting this study in an attempt to identify whether a warm-up period prior to operating impacts operative technique. All general surgery residents and MIS fellows were included in this IRB-approved randomized study. Participants were randomized to either warm-up or no warm-up groups. Participants randomized to the warm-up group completed a 10 min practice session in the simulation lab within 1 h of starting the case, using an FLS training box. At the conclusion of the operation, the participant was evaluated by the attending surgeon using the validated global rating scales of Reznick and Vassiliou. The attending surgeons were blinded to the use of pre-procedure warm-up. The results of the questionnaire were analyzed using student's t test with p warm-up (19) or no warm-up (21). There was a statistically significant improvement in depth perception (p = 0.02), bimanual dexterity (p = 0.01), and efficiency of movements (p = 0.03) for those randomized to warm-up. There was statistical improvement when we preformed a composite scoring of the attending evaluations for each of the Reznick (p = 0.008) and the Vassiliou (p = 0.01) global rating scales. Preoperative warm-up significantly improves depth perception, bimanual dexterity, and efficiency of movements, as well as improvement in composite scores as judged by the attending surgeon. The lack of self-perceived improvement by the residents may be a reflection of the high standards and intense self-critique that is common among surgical trainees. We believe that our findings, while preliminary, reflect that surgical performance can be enhanced through structured warm-up activities.

  4. Emergence of Multiscaling in a Random-Force Stirred Fluid

    Science.gov (United States)

    Yakhot, Victor; Donzis, Diego

    2017-07-01

    We consider the transition to strong turbulence in an infinite fluid stirred by a Gaussian random force. The transition is defined as a first appearance of anomalous scaling of normalized moments of velocity derivatives (dissipation rates) emerging from the low-Reynolds-number Gaussian background. It is shown that, due to multiscaling, strongly intermittent rare events can be quantitatively described in terms of an infinite number of different "Reynolds numbers" reflecting a multitude of anomalous scaling exponents. The theoretically predicted transition disappears at Rλ≤3 . The developed theory is in quantitative agreement with the outcome of large-scale numerical simulations.

  5. Reflective Practice: Origins and Interpretations

    Science.gov (United States)

    Reynolds, Michael

    2011-01-01

    The idea of reflection is central to the theory and practice of learning--especially learning which is grounded in past or current experience. This paper proposes a working definition of reflection and reviews its origins and recent developments. The author also provides an account of "critical reflection", including its rationale and…

  6. Berlin Reflectance Spectral Library (BRSL)

    Science.gov (United States)

    Henckel, D.; Arnold, G.; Kappel, D.; Moroz, L. V.; Markus, K.

    2017-09-01

    The Berlin Reflectance Spectral Library (BRSL) provides a collection of reflectance spectra between 0.3 and 17 µm. It was originally dedicated to support space missions to small solar system bodies. Meanwhile the library includes selections of biconical reflectance spectra for spectral data analysis of other planetary bodies as well. The library provides reference spectra of well-characterized terrestrial analogue materials and meteorites for interpretation of remote sensing reflectance spectra of planetary surfaces. We introduce the BRSL, summarize the data available, and access to use them for further relevant applications.

  7. Reflected Brownian motions in the KPZ universality class

    CERN Document Server

    Weiss, Thomas; Spohn, Herbert

    2017-01-01

    This book presents a detailed study of a system of interacting Brownian motions in one dimension. The interaction is point-like such that the n-th Brownian motion is reflected from the Brownian motion with label n-1. This model belongs to the Kardar-Parisi-Zhang (KPZ) universality class. In fact, because of the singular interaction, many universal properties can be established with rigor. They depend on the choice of initial conditions. Discussion addresses packed and periodic initial conditions (Chapter 5), stationary initial conditions (Chapter 6), and mixtures thereof (Chapter 7). The suitably scaled spatial process will be proven to converge to an Airy process in the long time limit. A chapter on determinantal random fields and another one on Airy processes are added to have the notes self-contained. These notes serve as an introduction to the KPZ universality class, illustrating the main concepts by means of a single model only. The notes will be of interest to readers from interacting diffusion processe...

  8. Reflecting Team as an Evaluation/learning Instrument for Self-reflection of Teachers

    Directory of Open Access Journals (Sweden)

    Michling Malgorzata D.

    2017-12-01

    Full Text Available The Reflecting Team (RT is a method derived from systemic therapy in the 1980s by the social psychiatrist Tom Andersen. It is increasingly being used in training and evaluation contexts. The aim of the method is to create a space for the development of diverse perspectives and appropriate ideas and solutions in which the integrity of the students/customers/clients is preserved and the acceptance of proposals is facilitated. To this end, the systems involved (advice seekers, consultants, and observers enter a common process of alternately directed and non-directed communication. The RT is not only suitable to address communication problems in group work and other educational situations, but it can also help to consider the traditional teaching and learning processes in a reflective way. Reflecting teams can also significantly improve the feedback and quality of teaching and learning. The article deals with the use of RT in the context of the collective exchange of teaching staff with their students. It uses a problem as an evaluation form and learning instrument to reflect on their pedagogical approach and, at the same time, their relationship with students during the lessons. This is to present the RT method for collegial exchange (Process Flow: Advice-seeker, teacher, Interviewer, RT and their need for teacher reflection as well as the experience of self-efficacy (empowerment and self-sufficiency.

  9. Born reflection kernel analysis and wave-equation reflection traveltime inversion in elastic media

    KAUST Repository

    Wang, Tengfei; Cheng, Jiubing

    2017-01-01

    Elastic reflection waveform inversion (ERWI) utilize the reflections to update the low and intermediate wavenumbers in the deeper part of model. However, ERWI suffers from the cycle-skipping problem due to the objective function of waveform residual

  10. Critical thinking and reflection exercises in a biochemistry course to improve prospective health professions students' attitudes toward physician-pharmacist collaboration.

    Science.gov (United States)

    Van Winkle, Lon J; Cornell, Susan; Fjortoft, Nancy; Bjork, Bryan C; Chandar, Nalini; Green, Jacalyn M; La Salle, Sophie; Viselli, Susan M; Burdick, Paulette; Lynch, Sean M

    2013-10-14

    To determine the impact of performing critical-thinking and reflection assignments within interdisciplinary learning teams in a biochemistry course on pharmacy students' and prospective health professions students' collaboration scores. Pharmacy students and prospective medical, dental, and other health professions students enrolled in a sequence of 2 required biochemistry courses. They were randomly assigned to interdisciplinary learning teams in which they were required to complete case assignments, thinking and reflection exercises, and a team service-learning project. Students were asked to complete the Scale of Attitudes Toward Physician-Pharmacist Collaboration prior to the first course, following the first course, and following the second course. The physician-pharmacist collaboration scores of prospective health professions students increased significantly (p<0.001). Having prospective health professions students work in teams with pharmacy students to think and reflect in and outside the classroom improves their attitudes toward physician-pharmacist collaboration.

  11. Critical Thinking and Reflection Exercises in a Biochemistry Course to Improve Prospective Health Professions Students’ Attitudes Toward Physician-Pharmacist Collaboration

    Science.gov (United States)

    Cornell, Susan; Fjortoft, Nancy; Bjork, Bryan C.; Chandar, Nalini; Green, Jacalyn M.; La Salle, Sophie; Viselli, Susan M.; Burdick, Paulette; Lynch, Sean M.

    2013-01-01

    Objective. To determine the impact of performing critical-thinking and reflection assignments within interdisciplinary learning teams in a biochemistry course on pharmacy students’ and prospective health professions students’ collaboration scores. Design. Pharmacy students and prospective medical, dental, and other health professions students enrolled in a sequence of 2 required biochemistry courses. They were randomly assigned to interdisciplinary learning teams in which they were required to complete case assignments, thinking and reflection exercises, and a team service-learning project. Assessment. Students were asked to complete the Scale of Attitudes Toward Physician-Pharmacist Collaboration prior to the first course, following the first course, and following the second course. The physician-pharmacist collaboration scores of prospective health professions students increased significantly (p<0.001). Conclusions. Having prospective health professions students work in teams with pharmacy students to think and reflect in and outside the classroom improves their attitudes toward physician-pharmacist collaboration. PMID:24159210

  12. Seasonal soybean crop reflectance

    Science.gov (United States)

    Lemaster, E. W. (Principal Investigator); Chance, J. E.

    1983-01-01

    Data are presented from field measurements of 1980 including 5 acquisitions of handheld radiometer reflectance measurements, 7 complete sets of parameters for implementing the Suits mode, and other biophysical parameters to characterize the soybean canopy. LANDSAT calculations on the simulated Brazilian soybean reflectance are included along with data collected during the summer and fall on 1981 on soybean single leaf optical parameters for three irrigation treatments. Tests of the Suits vegetative canopy reflectance model for the full hemisphere of observer directions as well as the nadir direction show moderate agreement for the visible channels of the MSS and poor agreement in the near infrared channel. Temporal changes in the spectral characteristics of the single leaves were seen to occur as a function of maturity which demonstrates that the absorptance of a soybean single leaf is more a function of thetransmittancee characteristics than the seasonally consistent single leaf reflectance.

  13. Biology Reflective Assessment Curriculum

    Science.gov (United States)

    Bayley, Cheryl Ann

    Often students and educators view assessments as an obligation and finality for a unit. In the current climate of high-stakes testing and accountability, the balance of time, resources and emphasis on students' scores related to assessment have been slanted considerably toward the summative side. This tension between assessment for accountability and assessment to inform teaching strains instruction and educators' ability to use that information to design learning opportunities that help students develop deeper conceptual understanding. A substantive body of research indicates that formative and reflective assessment can significantly improve student learning. Biology Reflective Assessment Curriculum (BRAC) examines support provided for high school science students through assessment practices. This investigation incorporates the usage of reflective assessments as a guiding practice for differentiated instruction and student choice. Reflective assessment is a metacognitive strategy that promotes self-monitoring and evaluation. The goals of the curriculum are to promote self-efficacy and conceptual understanding in students learning biology through developing their metacognitive awareness. BRAC was implemented in a high school biology classroom. Data from assessments, metacognitive surveys, self-efficacy surveys, reflective journals, student work, a culminating task and field notes were used to evaluate the effectiveness of the curriculum. The results suggest that students who develop their metacognitive skills developed a deeper conceptual understanding and improved feelings of self-efficacy when they were engaged in a reflective assessment unit embedded with student choice. BRAC is a tool for teachers to use assessments to assist students in becoming metacognitive and to guide student choice in learning opportunities.

  14. Students’ Learning through Reflective Journaling

    Directory of Open Access Journals (Sweden)

    Alvyda Liuolienė

    2011-04-01

    Full Text Available The aim of the article is to get acquainted with the types of journals used in education to help students to learn. The paper presents some ways of fostering student’s learning through reflective journaling. It also describes the key aspects of a new method ARRIVE cycle in connection with teachers preparation to use reflective journals in a classroom. The article also presents self-assessment in reflective journaling and students’ need to self-evaluate their learning process. Reflective journaling as central to students’ self-evaluation is described as a means of fostering metacognition.

  15. Dissenting in Reflective Conversations

    DEFF Research Database (Denmark)

    Bjørn, Pernille; Boulus, Nina

    2011-01-01

    Reflective monitoring of research practices is essential. However, we often lack formal training in the practices of doing action research, and descriptions of actual inquiry practice are seldom included in publications. Our aim is to provide a glimpse of self-reflective practices based on our...

  16. Enhancing Self-Practice/Self-Reflection (SP/SR) approach to cognitive behaviour training through the use of reflective blogs.

    Science.gov (United States)

    Farrand, Paul; Perry, Jon; Linsley, Sue

    2010-07-01

    Self-Practice/Self-Reflection (SP/SR) is increasingly beginning to feature as a central component of CBT training programmes (Bennett-Levy et al., 2001). Programmes including a reflective element, however, are not unproblematic and it has been documented that simply setting time aside for reflection does not necessarily result in trainees using such time to reflect. Such limitations may be overcome by including a requirement to post reflections on reflective blogs. To examine the effect that a requirement to contribute to a reflective blog had upon a SP/SR approach to CBT training. A focus group methodology was adopted with data analyzed using a general inductive qualitative approach. The requirement to use blogs to reflect upon the self-practice of CBT techniques enhanced SP/SR, established a learning community, and improved course supervision, although some technical difficulties arose. Consideration should be given towards using reflective blogs to support a SP/SR approach to CBT training. Benefits afforded by the use of reflective blogs further establish SP/SR as a valid and flexible training approach.

  17. Energy generation potential from coals of the Charqueadas Coalfield, RS, Brazil

    Science.gov (United States)

    Correa da Silva, Z. C.; Heemann, R.; Castro, L.; Ketzer, J. M.

    2009-04-01

    Three coal seams, I2B (Inferior 2), I1F (Inferior 1) and MB, from the Charqueadas Coalfield located in the central-east region of the State of Rio Grande do Sul, Southern Brazil were studied on the basis of geological, petrographic, chemical and geochemical techniques and correlated to the SR1, SR2 and SR3 coal seams from the Santa Rita Coalfield. The Charqueadas Coalfield reserves reach 2,993x106 metric tons of coal distributed in six coal seams. The study of sedimentary and organic facies is made on the subsurface data from five boreholes drilled in the area. There show a well marked lateral facies change from sub aquatic to sub aerial environment, conditioned by both the water level variations and the irregular palaeotopography of the basement. The coals change from limnic to forest-terrestrial moor types characterized by variations of composition in terms of macerals, microlithotypes and mineral matter. The coals are rich in mineral matter (28 to 40%); the vitrinite content reaches 50 %, inertinite 44 % and liptinite varies from 10 to 30 %, in mineral matter free basis. Among the microlithotypes carbominerite and vitrite are predominant. Rank studies carried out by different methods (vitrinite reflectance, max and red-green quotient among others) gave conflicting results, which are explained by the strong bituminization of the vitrinite. However, agreement between fluorescence measurements and organic geochemical parameters (e.g. CPI values) confirm that the coals are of a High Volatile Bituminous B/C (ASTM) or Gasflammkohle (DIN) rank. Based on these characteristics, the Charqueadas coal seams show great potential for use in Underground Coal Gasification (UCG) and Enhanced Coalbed Methane (ECBM) projects. Nowadays the state of Rio Grande do Sul is rapidly growing and needs to increase the energy efficiency to attend the industrial demands, filling the gap between supply and energy generation. As with conventional IGCC, UCG gas can be used to generate

  18. Asteroid thermal modeling in the presence of reflected sunlight

    Science.gov (United States)

    Myhrvold, Nathan

    2018-03-01

    A new derivation of simple asteroid thermal models is presented, investigating the need to account correctly for Kirchhoff's law of thermal radiation when IR observations contain substantial reflected sunlight. The framework applies to both the NEATM and related thermal models. A new parameterization of these models eliminates the dependence of thermal modeling on visible absolute magnitude H, which is not always available. Monte Carlo simulations are used to assess the potential impact of violating Kirchhoff's law on estimates of physical parameters such as diameter and IR albedo, with an emphasis on NEOWISE results. The NEOWISE papers use ten different models, applied to 12 different combinations of WISE data bands, in 47 different combinations. The most prevalent combinations are simulated and the accuracy of diameter estimates is found to be depend critically on the model and data band combination. In the best case of full thermal modeling of all four band the errors in an idealized model the 1σ (68.27%) confidence interval is -5% to +6%, but this combination is just 1.9% of NEOWISE results. Other combinations representing 42% of the NEOWISE results have about twice the CI at -10% to +12%, before accounting for errors due to irregular shape or other real world effects that are not simulated. The model and data band combinations found for the majority of NEOWISE results have much larger systematic and random errors. Kirchhoff's law violation by NEOWISE models leads to errors in estimation accuracy that are strongest for asteroids with W1, W2 band emissivity ɛ12 in both the lowest (0.605 ≤ɛ12 ≤ 0 . 780), and highest decile (0.969 ≤ɛ12 ≤ 0 . 988), corresponding to the highest and lowest deciles of near-IR albedo pIR. Systematic accuracy error between deciles ranges from a low of 5% to as much as 45%, and there are also differences in the random errors. Kirchhoff's law effects also produce large errors in NEOWISE estimates of pIR, particularly for high

  19. Validating the Persian Version of Reflective Thinking Questionnaire and Probing Iranian University Students' Reflective Thinking and Academic Achievement

    Directory of Open Access Journals (Sweden)

    Afsaneh Ghanizadeh

    2017-07-01

    Full Text Available Scholars in higher education deem reflective thinking as integral to the development of professional disciplinary practices. One of the major issues in studying reflective thinking pivots around its conceptualization and assessment. Over the years, researchers have used several methods and scales to measure reflective thinking. One of the most widely known scales of reflective thinking was constructed and validated by Kember et al. (2000. It is entitled 'Reflective Thinking Questionnaire (RTQ' and includes 16 items measuring four types of reflective thinking: understanding (UND; reflection (REF; critical reflection (CREF; habitual action (HA. The present study aimed at validating the Persian version of RTQ among one hundred ninety six English as a foreign language (EFL university students. It then scrutinized the role of reflective thinking in academic achievements measured by grade point average (GPA. The association of learners' reflective thinking style with their educational level and gender was also estimated. To conduct the research, the scale was first translated into Persian and its validity (computed via confirmatory factor analysis, convergent, and divergent validity estimates and reliability (computed via Cronbach's alpha were substantiated. It was indicated that among the comprising factors of reflective thinking, UND received the highest mean followed by REF and CREF

  20. Reflection-Based Learning for Professional Ethical Formation.

    Science.gov (United States)

    Branch, William T; George, Maura

    2017-04-01

    One way practitioners learn ethics is by reflecting on experience. They may reflect in the moment (reflection-in-action) or afterwards (reflection-on-action). We illustrate how a teaching clinician may transform relationships with patients and teach person-centered care through reflective learning. We discuss reflective learning pedagogies and present two case examples of our preferred method, guided group reflection using narratives. This method fosters moral development alongside professional identity formation in students and advanced learners. Our method for reflective learning addresses and enables processing of the most pressing ethical issues that learners encounter in practice. © 2017 American Medical Association. All Rights Reserved.

  1. Analytic Reflected Lightcurves for Exoplanets

    Science.gov (United States)

    Haggard, Hal M.; Cowan, Nicolas B.

    2018-04-01

    The disk-integrated reflected brightness of an exoplanet changes as a function of time due to orbital and rotational motion coupled with an inhomogeneous albedo map. We have previously derived analytic reflected lightcurves for spherical harmonic albedo maps in the special case of a synchronously-rotating planet on an edge-on orbit (Cowan, Fuentes & Haggard 2013). In this letter, we present analytic reflected lightcurves for the general case of a planet on an inclined orbit, with arbitrary spin period and non-zero obliquity. We do so for two different albedo basis maps: bright points (δ-maps), and spherical harmonics (Y_l^m-maps). In particular, we use Wigner D-matrices to express an harmonic lightcurve for an arbitrary viewing geometry as a non-linear combination of harmonic lightcurves for the simpler edge-on, synchronously rotating geometry. These solutions will enable future exploration of the degeneracies and information content of reflected lightcurves, as well as fast calculation of lightcurves for mapping exoplanets based on time-resolved photometry. To these ends we make available Exoplanet Analytic Reflected Lightcurves (EARL), a simple open-source code that allows rapid computation of reflected lightcurves.

  2. Reflection measurements for luminescent powders

    Science.gov (United States)

    Kroon, R. E.

    2018-04-01

    Luminescent materials are useful in applications varying from lighting and display technologies to document security features and medical research, amongst many others. Measurement of the excitation range is an important consideration, and absorption bands are often determined from a decrease in the measured diffuse reflectance of the material using a ultraviolet-visible (UV-vis) spectrophotometer with an integrating sphere. Such a system may provide questionable results when used to measure the reflectance of a luminescence material, which is demonstrated for a Tb doped silica phosphor, because the system cannot differentiate between the reflected light and luminescence. It is shown that more reliable results are achieved for this phosphor by measuring the reflectance using a synchronous zero-offset scan in a fluorescence spectrometer equipped with an integrating sphere. This method is therefore recommended instead of traditional reflectance measurements using a UV-vis spectrophotometer for luminescent powders.

  3. Fecal corticosterone reflects serum corticosterone in Florida sandhill cranes.

    Science.gov (United States)

    Ludders, J W; Langenberg, J A; Czekala, N M; Erb, H N

    2001-07-01

    Florida sandhill cranes (Grus canadensis pratensis) were conditioned to confinement 6 hr/day for 7 days. On day 8, each bird's jugular vein was catheterized, blood samples were drawn, and each crane was confined for 6 hr. Using a randomized, restricted cross-over design, cranes were injected intravenously with either 0.9% NaCl solution or ACTH (cosyntropin; Cortrosyn; 0.25 mg). During the 6 hr of confinement, fecal samples (feces and urine) were collected from each of five cranes immediately after defecation. Individual fecal samples were collected approximately at hourly intervals and assayed for corticosterone. We showed previously that serum corticosterone did not vary significantly following saline injection, but peaked significantly 60 min after ACTH injection. Maximal fecal corticosterone concentrations (ng/g) were greater (P cranes under controlled conditions, fecal corticosterone concentration reflects serum corticosterone levels, fecal corticosterone, Grus canadensis pratensis, sandhill cranes, serum corticosterone levels.

  4. Improving Inquiry Teaching through Reflection on Practice

    Science.gov (United States)

    Lotter, Christine R.; Miller, Cory

    2017-08-01

    In this paper, we explore middle school science teachers' learning of inquiry-based instructional strategies through reflection on practice teaching sessions during a summer enrichment program with middle level students. The reflection sessions were part of a larger year-long inquiry professional development program in which teachers learned science content and inquiry pedagogy. The program included a 2-week summer institute in which teachers participated in science content sessions, practice teaching to middle level students, and small group-facilitated reflection sessions on their teaching. For this study, data collection focused on teachers' recorded dialogue during the facilitator - run reflection sessions, the teachers' daily written reflections, a final written reflection, and a written reflection on a videotaped teaching session. We investigated the teachers' reflection levels and the themes teachers focused on during their reflection sessions. Teachers were found to reflect at various reflection levels, from simple description to a more sophisticated focus on how to improve student learning. Recurrent themes point to the importance of providing situated learning environments, such as the practice teaching with immediate reflection for teachers to have time to practice new instructional strategies and gain insight from peers and science educators on how to handle student learning issues.

  5. MODIS 250m burned area mapping based on an algorithm using change point detection and Markov random fields.

    Science.gov (United States)

    Mota, Bernardo; Pereira, Jose; Campagnolo, Manuel; Killick, Rebeca

    2013-04-01

    Area burned in tropical savannas of Brazil was mapped using MODIS-AQUA daily 250m resolution imagery by adapting one of the European Space Agency fire_CCI project burned area algorithms, based on change point detection and Markov random fields. The study area covers 1,44 Mkm2 and was performed with data from 2005. The daily 1000 m image quality layer was used for cloud and cloud shadow screening. The algorithm addresses each pixel as a time series and detects changes in the statistical properties of NIR reflectance values, to identify potential burning dates. The first step of the algorithm is robust filtering, to exclude outlier observations, followed by application of the Pruned Exact Linear Time (PELT) change point detection technique. Near-infrared (NIR) spectral reflectance changes between time segments, and post change NIR reflectance values are combined into a fire likelihood score. Change points corresponding to an increase in reflectance are dismissed as potential burn events, as are those occurring outside of a pre-defined fire season. In the last step of the algorithm, monthly burned area probability maps and detection date maps are converted to dichotomous (burned-unburned maps) using Markov random fields, which take into account both spatial and temporal relations in the potential burned area maps. A preliminary assessment of our results is performed by comparison with data from the MODIS 1km active fires and the 500m burned area products, taking into account differences in spatial resolution between the two sensors.

  6. Novel polarization beam splitter with a tolerance to large random disorder

    International Nuclear Information System (INIS)

    Zhou Jie; Shen Yifeng; Wang Yongchun; Zhan Yuan; Wu Fangfang; Guo Changqing

    2010-01-01

    We propose a design for a simple broad-angle polarization beam splitter (PBS) consisting of two rows of dielectric cylinders with different space periods. The finite-difference time-domain method simulations show that TM polarized light is reflected totally by this PBS but TE polarized light passes through it freely in a broad incident angle range (from -50 0 to 50 0 ). The PBS can work over a wide frequency range (from 0.22 x (c/a) to 0.28 x (c/a)) with a high efficiency. Moreover, the PBS structure has a novel capability of tolerance to large random disorder, which is very advantageous for practical applications. Even when a random disorder of 15%a (a is space period) is introduced into the radius and position of each cylinder, the PBS structure can still maintain almost the same good performance and high splitting efficiency.

  7. Sequence stratigraphy, organic petrology and chemistry applied to the upper and lower coal seams in the Candiota Coalfield, Parana Basin, RS, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, J.S. de; Kalkreuth, W. [Instituto de Geociencias, UFRGS, Porto Alegre (Brazil)

    2010-12-01

    The Permian age coal seams in the Candiota Coalfield represent the largest coal deposit of the country. Currently two seams are mined, called ''Camada Candiota Superior'' and ''Camada Candiota Inferior''. The other coal seams of the coalfield, seams S1-S9 (upper seams) and I1-I5 (lower seams) have as yet not been exploited. The objective of this paper is to perform a detailed sequence stratigraphic, petrologic and chemical study of the upper and lower coal seams, thereby generating data for assisting in the development and better use of the coal-bearing interval. The methodology includes application of the concepts of sequence stratigraphy, which includes the lithological interpretation of the core to establish the depositional environments and genetic correlation between facies associations to define parasequences and bounding surfaces; coal petrology (analysis of the reflectance of vitrinite, determination of the petrographic composition of the coals by maceral analyses), and chemical analyses such as sulphur determination, proximate analyses (ash, moisture, volatile matter, and fixed carbon), and elemental analyses. Three main depositional systems were so far identified: alluvial fan, fluvial system, lagoonal estuary system. This study shows that coal development was controlled by accommodation/accumulation rates, with coal seams with greater thickness and lateral continuity being formed within the transgressive systems tract (lagoonal depositional system) of parasequence 2 (PS2), indicating that the accumulation rates of the peat and distribution of the coal seams were controlled by stratigraphic setting. Vitrinite reflectances for the upper and lower coal seams are indicative of subbituminous rank (Rrandom = 0.36-0.47%), with evidence that anomalously low reflectance values are related to high mineral-matter contents. Maceral composition is highly variable, with some coal seams being extremely rich in inertinite (up to

  8. Testing models of basin inversion in the eastern North Sea using exceptionally accurate thermal and maturity data

    DEFF Research Database (Denmark)

    Nielsen, S.B.; Clausen, O.R.; Gallagher, Kerry

    2011-01-01

    the thermal history information contained in high quality thermal maturity data comprising temperature profiles, vitrinite reflectance and apatite fission track data. Having remained open for experimental purposes, the data of two of the deep wells (Aars-1 and Farsoe-1) are of exceptionally high quality. Here...... about the magnitude of deposition and erosion during this hiatus. We use Markov Chain Monte Carlo with a transient one-dimensional thermal model to explore the parameter space of potential thermal history solutions, using the different available data as constraints. The variable parameters comprise...... inversion of the STZ. This is in agreement with numerical rheological models of inversion zone dynamics, which explain how marginal trough subsidence occurred as a consequence of late Cretaceous compressional inversion and erosion along the inversion axis (Nielsen et al. 2005, 2007). Following this, the in-plane...

  9. Maturity in the Styrian Basin. Maturitaet im Steirischen Tertiaerbecken

    Energy Technology Data Exchange (ETDEWEB)

    Sachsenhofer, R.F. (Montanuniversitaet Leoben (Austria). Inst. fuer Geowissenschaften/Geologie)

    1991-01-01

    The Styrian basin, situated at the south-eastern margin of the Alps, contains up to 3 km of Ottnangian to Pliocene sedimentary rocks. Main subsidence occured between Ottnangian and Sarmatian. Miocene and Plio-/Pleistocene volcanic phases can be distinguished. Maturity in the Styrian basin was studied with vitrinite reflectance curves of 25 boreholes. The oil window lies at shallow depths in the vicinty of Miocene volcanos. This is due to high heating rate during Karpatian to Lower Badenian times. Depth and thickness of the oil window increase with increasing distance from these volcanos. At a distance of some kilometers the thermal influence of this Miocene volcanism disappears. According to high recent heat flow the oil window is located below 1 500 to 2 000 m in these parts of the basin. An influence of Plio-/Pleistocene volcanism on maturity cannot be observed. (orig.).

  10. Random pulse generator

    International Nuclear Information System (INIS)

    Guo Ya'nan; Jin Dapeng; Zhao Dixin; Liu Zhen'an; Qiao Qiao; Chinese Academy of Sciences, Beijing

    2007-01-01

    Due to the randomness of radioactive decay and nuclear reaction, the signals from detectors are random in time. But normal pulse generator generates periodical pulses. To measure the performances of nuclear electronic devices under random inputs, a random generator is necessary. Types of random pulse generator are reviewed, 2 digital random pulse generators are introduced. (authors)

  11. Reflecting on life, not on the mind – The concept of self-reflection without stability

    DEFF Research Database (Denmark)

    Jensen, Lasse Meinert

    This paper presents a critique of the concept of “reflection” and a theoretical alternative. I’ll argue that current notions of reflections to a large extend deals only with “meta-reflection” or “self-reflection”, and that the main problem with such conceptualizations is their preoccupation...... with “stability”. When self-reflection is conceptualized as a second-order process charged with creating diachronic continuity in the person’s life, as it often is in both philosophy (Frankfurt, 1971), cognitive theory (Carver, Scheier & Fulton, 2008), and narrative theories of personality (McAdams, 2008......), “Stability” and how it is brought about, becomes the main concern. But presupposing “stability” as the main aim of self-reflection isolates reflection to a mental realm. Human beings are certainly self-conscious, but – following Dreier (1999), when he points out that reflection is not a distancing from...

  12. The RANDOM computer program: A linear congruential random number generator

    Science.gov (United States)

    Miles, R. F., Jr.

    1986-01-01

    The RANDOM Computer Program is a FORTRAN program for generating random number sequences and testing linear congruential random number generators (LCGs). The linear congruential form of random number generator is discussed, and the selection of parameters of an LCG for a microcomputer described. This document describes the following: (1) The RANDOM Computer Program; (2) RANDOM.MOD, the computer code needed to implement an LCG in a FORTRAN program; and (3) The RANCYCLE and the ARITH Computer Programs that provide computational assistance in the selection of parameters for an LCG. The RANDOM, RANCYCLE, and ARITH Computer Programs are written in Microsoft FORTRAN for the IBM PC microcomputer and its compatibles. With only minor modifications, the RANDOM Computer Program and its LCG can be run on most micromputers or mainframe computers.

  13. Study on Stationarity of Random Load Spectrum Based on the Special Road

    Science.gov (United States)

    Yan, Huawen; Zhang, Weigong; Wang, Dong

    2017-09-01

    In the special road quality assessment method, there is a method using a wheel force sensor, the essence of this method is collecting the load spectrum of the car to reflect the quality of road. According to the definition of stochastic process, it is easy to find that the load spectrum is a stochastic process. However, the analysis method and application range of different random processes are very different, especially in engineering practice, which will directly affect the design and development of the experiment. Therefore, determining the type of a random process has important practical significance. Based on the analysis of the digital characteristics of road load spectrum, this paper determines that the road load spectrum in this experiment belongs to a stationary stochastic process, paving the way for the follow-up modeling and feature extraction of the special road.

  14. Random walkers with extreme value memory: modelling the peak-end rule

    Science.gov (United States)

    Harris, Rosemary J.

    2015-05-01

    Motivated by the psychological literature on the ‘peak-end rule’ for remembered experience, we perform an analysis within a random walk framework of a discrete choice model where agents’ future choices depend on the peak memory of their past experiences. In particular, we use this approach to investigate whether increased noise/disruption always leads to more switching between decisions. Here extreme value theory illuminates different classes of dynamics indicating that the long-time behaviour is dependent on the scale used for reflection; this could have implications, for example, in questionnaire design.

  15. Low-temperature relative reflectivity measurements of reflective and scintillating foils used in rare event searches

    Science.gov (United States)

    Langenkämper, A.; Ulrich, A.; Defay, X.; Feilitzsch, F. v.; Lanfranchi, J.-C.; Mondragón, E.; Münster, A.; Oppenheimer, C.; Potzel, W.; Roth, S.; Schönert, S.; Steiger, H.; Trinh Thi, H. H.; Wawoczny, S.; Willers, M.; Zöller, A.

    2018-03-01

    In this work we investigate the reflectivity of highly reflective multilayer polymer foils used in the CRESST experiment. The CRESST experiment searches directly for dark matter via operating scintillating CaWO4 crystals as targets for elastic dark matter-nucleon scattering. In order to suppress background events, the experiment employs the so-called phonon-light technique which is based on the simultaneous measurement of the heat signal in the main CaWO4 target crystal and of the emitted scintillation light with a separate cryogenic light detector. Both detectors are surrounded by a highly reflective and scintillating multilayer polymer foil to increase the light collection efficiency and to veto surface backgrounds. While this study is motivated by the CRESST experiment, the results are also relevant for other rare event searches using scintillating cryogenic bolometers in the field of the search of dark matter and neutrinoless double beta decay (0 νββ). In this work a dedicated experiment has been set up to determine the relative reflectivity at 300 K and 20 K of three multilayer foils ("VM2000", "VM2002", "Vikuiti") produced by the company 3M. The intensity of a light beam reflected off the foil is measured with a CCD camera. The ratio of the intensities at 300 K and 20 K corresponds to the relative reflectivity change. The measurements performed in this work show no variation of the reflectivity with temperature at a level of ∼1%.

  16. Random walk, diffusion and mixing in simulations of scalar transport in fluid flows

    International Nuclear Information System (INIS)

    Klimenko, A Y

    2008-01-01

    Physical similarity and mathematical equivalence of continuous diffusion and particle random walk form one of the cornerstones of modern physics and the theory of stochastic processes. In many applied models used in simulation of turbulent transport and turbulent combustion, mixing between particles is used to reflect the influence of the continuous diffusion terms in the transport equations. We show that the continuous scalar transport and diffusion can be accurately specified by means of mixing between randomly walking Lagrangian particles with scalar properties and assess errors associated with this scheme. This gives an alternative formulation for the stochastic process which is selected to represent the continuous diffusion. This paper focuses on statistical errors and deals with relatively simple cases, where one-particle distributions are sufficient for a complete description of the problem.

  17. Reflected forward-backward SDEs and obstacle problems with boundary conditions

    Directory of Open Access Journals (Sweden)

    Jin Ma

    2001-01-01

    Full Text Available In this paper we study a class of forward-backward stochastic differential equations with reflecting boundary conditions (FBSDER for short. More precisely, we consider the case in which the forward component of the FBSDER is restricted to a fixed, convex region, and the backward component will stay, at each fixed time, in a convex region that may depend on time and is possibly random. The solvability of such FBSDER is studied in a fairly general way. We also prove that if the coefficients are all deterministic and the backward equation is one-dimensional, then the adapted solution of such FBSDER will give the viscosity solution of a quasilinear variational inequality (obstacle problem with a Neumann boundary condition. As an application, we study how the solvability of FBSDERs is related to the solvability of an American game option.

  18. On a randomly imperfect spherical cap pressurized by a random ...

    African Journals Online (AJOL)

    On a randomly imperfect spherical cap pressurized by a random dynamic load. ... In this paper, we investigate a dynamical system in a random setting of dual ... characterization of the random process for determining the dynamic buckling load ...

  19. Feeling Thanks and Saying Thanks: A Randomized Controlled Trial Examining If and How Socially Oriented Gratitude Journals Work.

    Science.gov (United States)

    O'Connell, Brenda H; O'Shea, Deirdre; Gallagher, Stephen

    2017-10-01

    This study examined the effect of a reflective interpersonal gratitude journal, a reflective-behavioral interpersonal gratitude journal and an active control journal, on primary qualities of well-being and depression. Participants (n = 192; 67.2% female) completed this 3-month longitudinal randomized controlled design. Participants in the reflective-behavioral condition experienced the greatest improvements in affect balance and reductions in depression at immediate posttest. Both gratitude interventions improved affect balance at 1 month, compared to the control. Changes in affect balance for those in the reflective-behavioral condition were mediated by the rate at which people expressed gratitude in their existing relationships. This effect was moderated by participant's baseline depressive status. Expressing felt gratitude to others appears to be a crucial step in deriving benefits, and these benefits may not be limited to the emotionally healthy. Given the applied popularity of gratitude interventions, understanding not only if but also how they work is essential. © 2017 Wiley Periodicals, Inc.

  20. STUDY OF REFLECTION COEFFICIENT DISTRIBUTION FOR ANTI-REFLECTION COATINGS ON SMALL-RADIUS OPTICAL PARTS

    Directory of Open Access Journals (Sweden)

    L. A. Gubanova

    2015-03-01

    Full Text Available The paper deals with findings for the energy reflection coefficient distribution of anti- reflection coating along the surface of optical elements with a very small radius (2-12 mm. The factors influencing the magnitude of the surface area of the optical element, in which the energy reflection coefficient is constant, were detected. The main principles for theoretical models that describe the spectral characteristics of the multilayer interference coatings were used to achieve these objectives. The relative size of the enlightenment area is defined as the ratio of the radius for the optical element surface, where the reflection is less than a certain value, to its radius (ρ/r. The result of research is the following: this size is constant for a different value of the curvature radius for the optical element made of the same material. Its value is determined by the refractive index of material (nm, from which the optical element was made, and the design of antireflection coatings. For single-layer coatings this value is ρ/r = 0.5 when nm = 1.51; and ρ/r = 0.73 when nm = 1.75; for two-layer coatings ρ/r = 0.35 when nm = 1.51 and ρ/r = 0.41 when nm = 1.75. It is shown that with increasing of the material refractive index for the substrate size, the area of minimum reflection coefficient is increased. The paper considers a single-layer, two-layer, three-layer and five-layer structures of antireflection coatings. The findings give the possibility to conclude that equal thickness coverings formed on the optical element surface with a small radius make no equal reflection from the entire surface, and distribution of the layer thickness needs to be looked for, providing a uniform radiation reflection at all points of the spherical surface.

  1. Fragments on teachers' reflective practicum

    Directory of Open Access Journals (Sweden)

    Živković Predrag Ž.

    2013-01-01

    Full Text Available in many historical and comparative overviews of the works, in which there is an analytical discussion of the dominant pedagogical theories in the twentieth century, John Dewey (Dewey, 1933 is referred to as the founder and creator of the concept of reflection (reflective thought and knowledge in practice. Reflection as a concept is understood as the forms and the form of problem solving, as well as continuously thinking about the causes of problems in situations in situ, including active and systematically and consistently changing connecting ideas with solutions to the problems and situations that preceded them (Hatton & Smith, 1995. Reflective thinking is the most general level to tackle practical problems, allowing the ''recommended'' doubts and confusion before proposing possible solutions to the problem. Dewey wrote about a reflective action which refers to the use of solutions to the problem and to thinking through the course of the action. in later works of the authors who have dealt with this problem, an unambiguous link can be observed between the so-called ''professional'' action and the reflection on action which, in this cyclical relationship, leads to visible changes (Zeichner & Gore, 1984. Already at first glance, this implies a connection with experiential learning and adult position of observation and reflection in various models of experiential learning, which will be discussed later. it would be useful to compare this method with a cyclic action of routine as an expression of impulse, tradition and authority. Reflective action, as opposed to the routine, is a consistently and carefully thought-out action (practice reflection, which is an ''awakened'' knowledge and belief, and that is an expression of openness, accountability and commitment. We are ready for reflection, says Schon, when the ''knowledge-in-action'' - a kind of knowledge that professionals notice when it is acted spontaneously - occurs suddenly and unintentionally

  2. Biodiversity Measurement Using Indices Based on Hyperspectral Reflectance on the Coast of Lagos

    Science.gov (United States)

    Omodanisi, E. O.; Salami, A. T.

    2013-12-01

    Hyperspectral measurements provide explicit measurements which can be used in the analysis of biodiversity change. This study was carried out in the coastal area of Lagos State, Nigeria. The objective of this study was to determine if gasoline seepage affects vegetation species distribution and reflectance; with the view to analyzing the vegetation condition. To evaluate the potential of different reflectance spectroscopy of species, the ASD Handheld2 Spectrometer was used. Three identified impacted plots of 30m by 30m were selected randomly and a control plot established in relatively undisturbed vegetated areas away from but perpendicular to the source of seepage. Each identified plot and the control consisted of five transects and measurement were taken at every 2m with about four reflectance measurement per sample point, to average out differences in reflectance as a result of different leaf angles. The radiance output of the spectrometer was converted into reflectance using the reflectance of a white reference over a standardized white spectralon panel. Indices such as Normalized Differential Vegetation Index, RedEdge Normalized Difference Vegetation Index, Soil Adjusted Vegetation Index, Ratio Vegetation Index and Volgelmann RedEdge Index 1 were calculated to accurately estimate the chlorophyll content in the vegetation within optimal band wavelength. Shannon-Weiner's index, Spearman's rank correlation and Analysis of Variance were used to analyze the data. Cocos nucifera was observed to be the most dominant species with a relative abundance of 47.27% while Ananas comosus recorded the lowest relative abundance of 21.8%. In the control plot, Cocos nucifera had the highest relative abundance of 42.3% and Mangifera indica with the least relative abundance of 16.7%. The relationship between the indices and chlorophyll content of the vegetation were significantly higher at (p>0.01) for all the indices in all the plots; however, RedEdgeNDVI and VOG1 indices had the

  3. Ultra-broadband and planar sound diffuser with high uniformity of reflected intensity

    Science.gov (United States)

    Fan, Xu-Dong; Zhu, Yi-Fan; Liang, Bin; Yang, Jing; Yang, Jun; Cheng, Jian-Chun

    2017-09-01

    Schroeder diffusers, as a classical design of acoustic diffusers proposed over 40 years ago, play key roles in many practical scenarios ranging from architectural acoustics to noise control to particle manipulation. Despite the great success of conventional acoustic diffusers, it is still worth pursuing ideal acoustic diffusers that are essentially expected to produce perfect sound diffuse reflection within the unlimited bandwidth. Here, we propose a different mechanism for designing acoustic diffusers to overcome the basic limits in intensity uniformity and working bandwidth in the previous designs and demonstrate a practical implementation by acoustic metamaterials with dispersionless phase-steering capability. In stark contrast to the existing production of diffuse fields relying on random scattering of sound energy by using a specific mathematical number sequence of periodically distributed unit cells, we directly mold the reflected wavefront into the desired shape by precisely manipulating the local phases of individual subwavelength metastructures. We also benchmark our design via numerical simulation with a commercially available Schroeder diffuser, and the results verify that our proposed diffuser scatters incident acoustic energy into all directions more uniformly within an ultra-broad band regardless of the incident angle. Furthermore, our design enables further improvement of the working bandwidth just by simply downscaling each individual element. With ultra-broadband functionality and high uniformity of reflected intensity, our metamaterial-based production of the diffusive field opens a route to the design and application of acoustic diffusers and may have a significant impact on various fields such as architectural acoustics and medical ultrasound imaging/treatment.

  4. A Data-Driven Reflectance Model

    OpenAIRE

    Matusik, Wojciech; Pfister, Hanspeter; Brand, Matt; McMillan, Leonard

    2003-01-01

    We present a generative model for isotropic bidirectional reflectance distribution functions (BRDFs) based on acquired reflectance data. Instead of using analytical reflectance models, we represent each BRDF as a dense set of measurements. This allows us to interpolate and extrapolate in the space of acquired BRDFs to create new BRDFs. We treat each acquired BRDF as a single high-dimensional vector taken from a space of all possible BRDFs. We apply both linear (subspace) and non-linear (manif...

  5. Quantum random flip-flop and its applications in random frequency synthesis and true random number generation

    Energy Technology Data Exchange (ETDEWEB)

    Stipčević, Mario, E-mail: mario.stipcevic@irb.hr [Photonics and Quantum Optics Research Unit, Center of Excellence for Advanced Materials and Sensing Devices, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb (Croatia)

    2016-03-15

    In this work, a new type of elementary logic circuit, named random flip-flop (RFF), is proposed, experimentally realized, and studied. Unlike conventional Boolean logic circuits whose action is deterministic and highly reproducible, the action of a RFF is intentionally made maximally unpredictable and, in the proposed realization, derived from a fundamentally random process of emission and detection of light quanta. We demonstrate novel applications of RFF in randomness preserving frequency division, random frequency synthesis, and random number generation. Possible usages of these applications in the information and communication technology, cryptographic hardware, and testing equipment are discussed.

  6. Sutherland models for complex reflection groups

    International Nuclear Information System (INIS)

    Crampe, N.; Young, C.A.S.

    2008-01-01

    There are known to be integrable Sutherland models associated to every real root system, or, which is almost equivalent, to every real reflection group. Real reflection groups are special cases of complex reflection groups. In this paper we associate certain integrable Sutherland models to the classical family of complex reflection groups. Internal degrees of freedom are introduced, defining dynamical spin chains, and the freezing limit taken to obtain static chains of Haldane-Shastry type. By considering the relation of these models to the usual BC N case, we are led to systems with both real and complex reflection groups as symmetries. We demonstrate their integrability by means of new Dunkl operators, associated to wreath products of dihedral groups

  7. The Effects of Coaching Using a Reflective Framework on Early Childhood Science Teachers' Depth of Reflection and Change in Practice

    Science.gov (United States)

    Bloomquist, Debra L.

    This embedded-mixed methods study examined if the use of a reflective framework with guiding prompts could support early childhood science teachers in improving their reflective practice and subsequently changing their pedagogy. It further investigated whether type of cognitive coaching group, individual or collaborative, impacted teacher depth of reflection and change in practice. Data included teacher reflections that were rated using the Level of Reflection-On-Action Assessment, reflective codes and inductive themes, as well as videos of participants lessons coded using the SCIIENCE instrument. Findings demonstrated that through guided reflection, teachers developed reflective thinking skills, and through this reflection became more critical and began to improve their pedagogical practice. Further findings supported that collaborative cognitive coaching may not be the most effective professional development for all teachers; as some teachers in the study were found to have difficulty improving their reflectivity and thus their teaching practice. Based on these findings it is recommended that coaches and designers of professional development continue to use reflective frameworks with guiding prompts to support teachers in the reflective process, but take into consideration that coaching may need to be differentiated for the various reflective levels demonstrated by teachers. Future studies will be needed to establish why some teachers have difficulty with the reflective process and how coaches or designers of professional development can further assist these teachers in becoming more critical reflectors.

  8. Low reflectance radio frequency load

    Science.gov (United States)

    Ives, R. Lawrence; Mizuhara, Yosuke M

    2014-04-01

    A load for traveling microwave energy has an absorptive volume defined by cylindrical body enclosed by a first end cap and a second end cap. The first end cap has an aperture for the passage of an input waveguide with a rotating part that is coupled to a reflective mirror. The inner surfaces of the absorptive volume consist of a resistive material or are coated with a coating which absorbs a fraction of incident RF energy, and the remainder of the RF energy reflects. The angle of the reflector and end caps is selected such that reflected RF energy dissipates an increasing percentage of the remaining RF energy at each reflection, and the reflected RF energy which returns to the rotating mirror is directed to the back surface of the rotating reflector, and is not coupled to the input waveguide. Additionally, the reflector may have a surface which generates a more uniform power distribution function axially and laterally, to increase the power handling capability of the RF load. The input waveguide may be corrugated for HE11 mode input energy.

  9. Random-field induced memory effects in inhomogeneously diluted antiferromagnets K2NixZn1−xF4

    DEFF Research Database (Denmark)

    Dikken, B. J.; Arts, A. F. M.; de Wijn, H. W.

    1986-01-01

    Using neutron diffraction a random-field generated memory is observed in K2NixZn1−xF4 with x = 0.96, 0.85, and 0.75. The intensities and profiles of magnetic Bragg reflections are found to follow unique trajectories determined by switching the external magnetic field on and off while cooling...

  10. The Importance of Reflective Practice in Nursing

    Directory of Open Access Journals (Sweden)

    Lauren Caldwell

    2013-01-01

    Full Text Available Reflection is an essential attribute for the development of autonomous, critical, and advanced practitioners (Mantzoukas & Jasper, 2004. According to Chong (2009, “Reflective practice should be a continuous cycle in which experience and reflection on experiences are inter-related” (p. 112. Studies have shown that nurses who take the time to reflect on their daily experiences provide enhanced nursing care, have a better understanding of theiractions, which in return develops their professional skills (Hansebo & Kihlgren, 2001. Reflective practice is the ability to examine ones actions and experiences with the outcome of developing their practice and enhancing clinicalknowledge. Reflective practice affects all levels of nursing, from students, to advanced practice nursing students, aswell as practicing nurses. Reflective practice is an important component of the nursing curriculum. Research has shown the relationship between student nurses and their mentors is vital. In order for reflection to be effective open-mindedness, courage, and a willingness to accept, and act on, criticism must be present (Bulmam, Lathlean, & Gobbi, 2012. This paper will explore the current literature and implications related to reflective practice in nursing.

  11. Workplace diaries promoting reflective practice in radiation therapy

    International Nuclear Information System (INIS)

    Chapman, Naomi; Dempsey, Shane E.; Warren-Forward, Helen M.

    2009-01-01

    Competency standards usually describe that radiation therapists are expected to display characteristics of reflective practice. Many radiation therapists may be unequipped to undertake reflective practice or produce evidence of reflective practice due to limited understanding of the process. There are many models to guide practitioners in their reflective journeys, however, the literature describing reflective practice can appear confusing. This paper will discuss the role of reflective practice, provide a definition for reflective practice and define concepts central to reflective journaling or workplace diaries. The paper will offer practical advice to increase radiation therapists knowledge and skills in the use of reflective workplace diaries.

  12. Workplace diaries promoting reflective practice in radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, Naomi [Medical Radiation Science, Faculty of Health Science, Box 16 Hunter Building, University of Newcastle, Callaghan, NSW 2308 (Australia)], E-mail: naomi.chapman@newcastle.edu.au; Dempsey, Shane E. [Medical Radiation Science, Faculty of Health Science, Box 16 Hunter Building, University of Newcastle, Callaghan, NSW 2308 (Australia)], E-mail: shane.e.dempsey@newcastle.edu.au; Warren-Forward, Helen M. [Medical Radiation Science, Faculty of Health Science, Box 16 Hunter Building, University of Newcastle, Callaghan, NSW 2308 (Australia)], E-mail: helen.warren-forward@newcastle.edu.au

    2009-05-15

    Competency standards usually describe that radiation therapists are expected to display characteristics of reflective practice. Many radiation therapists may be unequipped to undertake reflective practice or produce evidence of reflective practice due to limited understanding of the process. There are many models to guide practitioners in their reflective journeys, however, the literature describing reflective practice can appear confusing. This paper will discuss the role of reflective practice, provide a definition for reflective practice and define concepts central to reflective journaling or workplace diaries. The paper will offer practical advice to increase radiation therapists knowledge and skills in the use of reflective workplace diaries.

  13. Protective effects of flavanol-rich dark chocolate on endothelial function and wave reflection during acute hyperglycemia.

    Science.gov (United States)

    Grassi, Davide; Desideri, Giovambattista; Necozione, Stefano; Ruggieri, Fabrizio; Blumberg, Jeffrey B; Stornello, Michele; Ferri, Claudio

    2012-09-01

    Nitric oxide plays a pivotal role in regulating vascular tone. Different studies show endothelial function is impaired during hyperglycemia. Dark chocolate increases flow-mediated dilation in healthy and hypertensive subjects with and without glucose intolerance; however, the effect of pretreatment with dark chocolate on endothelial function and other vascular responses to hyperglycemia has not been examined. Therefore, we aimed to investigate the effects of flavanol-rich dark chocolate administration on (1) flow-mediated dilation and wave reflections; (2) blood pressure, endothelin-1 and oxidative stress, before and after oral glucose tolerance test (OGTT). Twelve healthy volunteers (5 males, 28.2±2.7 years) randomly received either 100 g/d dark chocolate or flavanol-free white chocolate for 3 days. After 7 days washout period, volunteers were switched to the other treatment. Flow-mediated dilation, stiffness index, reflection index, peak-to-peak time, blood pressure, endothelin-1 and 8-iso-PGF(2α) were evaluated after each treatment phase and OGTT. Compared with white chocolate, dark chocolate ingestion improved flow-mediated dilation (P=0.03), wave reflections, endothelin-1 and 8-iso-PGF(2α) (Pwave reflections, blood pressure, and endothelin-1 and 8-iso-PGF(2α) increased after OGTT. OGTT causes acute, transient impairment of endothelial function and oxidative stress, which is attenuated by flavanol-rich dark chocolate. These results suggest cocoa flavanols may contribute to vascular health by reducing the postprandial impairment of arterial function associated with the pathogenesis of atherosclerosis.

  14. An Access Control Framework for Reflective Middleware

    Institute of Scientific and Technical Information of China (English)

    Gang Huang; Lian-Shan Sun

    2008-01-01

    Reflective middleware opens up the implementation details of middleware platform and applications at runtime for improving the adaptability of middleware-based systems. However, such openness brings new challenges to access control of the middleware-based systems.Some users can access the system via reflective entities, which sometimes cannot be protected by access control mechanisms of traditional middleware. To deliver high adaptability securely, reflective middleware should be equipped with proper access control mechanisms for potential access control holes induced by reflection. One reason of integrating these mechanisms in reflective middleware is that one goal of reflective middleware is to equip applications with reflection capabilities as transparent as possible. This paper studies how to design a reflective J2EE middlewarePKUAS with access control in mind. At first, a computation model of reflective system is built to identify all possible access control points induced by reflection. Then a set of access control mechanisms, including the wrapper of MBeans and a hierarchy of Java class loaders, are equipped for controlling the identified access control points. These mechanisms together with J2EE access control mechanism form the access control framework for PKUAS. The paper evaluates the security and the performance overheads of the framework in quality and quantity.

  15. Reflection measurements of microwave absorbers

    Science.gov (United States)

    Baker, Dirk E.; van der Neut, Cornelis A.

    1988-12-01

    A swept-frequency interferometer is described for making rapid, real-time assessments of localized inhomogeneities in planar microwave absorber panels. An aperture-matched exponential horn is used to reduce residual reflections in the system to about -37 dB. This residual reflection is adequate for making comparative measurements on planar absorber panels whose reflectivities usually fall in the -15 to -25 dB range. Reflectivity measurements on a variety of planar absorber panels show that multilayer Jaumann absorbers have the greatest inhomogeneity, while honeycomb absorbers generally have excellent homogeneity within a sheet and from sheet to sheet. The test setup is also used to measure the center frequencies of resonant absorbers. With directional couplers and aperture-matched exponential horns, the technique can be easily applied in the standard 2 to 40 GHz waveguide bands.

  16. Randomized Algorithms for Analysis and Control of Uncertain Systems With Applications

    CERN Document Server

    Tempo, Roberto; Dabbene, Fabrizio

    2013-01-01

    The presence of uncertainty in a system description has always been a critical issue in control. The main objective of Randomized Algorithms for Analysis and Control of Uncertain Systems, with Applications (Second Edition) is to introduce the reader to the fundamentals of probabilistic methods in the analysis and design of systems subject to deterministic and stochastic uncertainty. The approach propounded by this text guarantees a reduction in the computational complexity of classical  control algorithms and in the conservativeness of standard robust control techniques. The second edition has been thoroughly updated to reflect recent research and new applications with chapters on statistical learning theory, sequential methods for control and the scenario approach being completely rewritten.   Features: ·         self-contained treatment explaining Monte Carlo and Las Vegas randomized algorithms from their genesis in the principles of probability theory to their use for system analysis; ·    ...

  17. Layered magnets: polarized neutron reflection studies

    Energy Technology Data Exchange (ETDEWEB)

    Zabel, H; Schreyer, A [Ruhr-Univ. Bochum, Lehrstuhl fuer Experimentalphysik/Festkoerperphysik, Bochum (Germany)

    1996-11-01

    Neutron reflectivity measurements from extended surfaces, thin films and superlattices provide information on the chemical profile parallel to the film normal, including film thicknesses, average composition and interfacial roughness parameters. Reflectivity measurements with polarized neutrons are particularly powerful for analyzing the magnetic density profiles in thin films and superlattices in addition to chemical profiles. The basic theory of polarized neutron reflectivity is provided, followed by some examples and more recent applications concerning polarized neutron reflectivity studies from exchange coupled Fe/Cr superlattices. (author) 5 figs., 13 refs.

  18. A comparison of random walks in dependent random environments

    NARCIS (Netherlands)

    Scheinhardt, Willem R.W.; Kroese, Dirk

    We provide exact computations for the drift of random walks in dependent random environments, including $k$-dependent and moving average environments. We show how the drift can be characterized and evaluated using Perron–Frobenius theory. Comparing random walks in various dependent environments, we

  19. A random network based, node attraction facilitated network evolution method

    Directory of Open Access Journals (Sweden)

    WenJun Zhang

    2016-03-01

    Full Text Available In present study, I present a method of network evolution that based on random network, and facilitated by node attraction. In this method, I assume that the initial network is a random network, or a given initial network. When a node is ready to connect, it tends to link to the node already owning the most connections, which coincides with the general rule (Barabasi and Albert, 1999 of node connecting. In addition, a node may randomly disconnect a connection i.e., the addition of connections in the network is accompanied by the pruning of some connections. The dynamics of network evolution is determined of the attraction factor Lamda of nodes, the probability of node connection, the probability of node disconnection, and the expected initial connectance. The attraction factor of nodes, the probability of node connection, and the probability of node disconnection are time and node varying. Various dynamics can be achieved by adjusting these parameters. Effects of simplified parameters on network evolution are analyzed. The changes of attraction factor Lamda can reflect various effects of the node degree on connection mechanism. Even the changes of Lamda only will generate various networks from the random to the complex. Therefore, the present algorithm can be treated as a general model for network evolution. Modeling results show that to generate a power-law type of network, the likelihood of a node attracting connections is dependent upon the power function of the node's degree with a higher-order power. Matlab codes for simplified version of the method are provided.

  20. Reflection and Reasoning in Moral Judgment

    Science.gov (United States)

    Paxton, Joseph M.; Ungar, Leo; Greene, Joshua D.

    2012-01-01

    While there is much evidence for the influence of automatic emotional responses on moral judgment, the roles of reflection and reasoning remain uncertain. In Experiment 1, we induced subjects to be more reflective by completing the Cognitive Reflection Test (CRT) prior to responding to moral dilemmas. This manipulation increased utilitarian…

  1. Developing Mathematical Practices through Reflection Cycles

    Science.gov (United States)

    Reinholz, Daniel L.

    2016-01-01

    This paper focuses on reflection in learning mathematical practices. While there is a long history of research on reflection in mathematics, it has focused primarily on the development of conceptual understanding. Building on notion of learning as participation in social practices, this paper broadens the theory of reflection in mathematics…

  2. Positive Stress and Reflective Practice Among Entrepreneurs

    Directory of Open Access Journals (Sweden)

    Kati Tikkamäki

    2016-01-01

    Full Text Available While heavy stress loads seem an unavoidable aspect of entrepreneurship, the positive side of stress (often referred to as ‘eustress’ remains a neglected area of research. This paper contributes to entrepreneurship research by linking the research streams of eustress and reflective practice. As a tool for analysing and developing thoughts and actions, reflective practice plays an important role in the interpretative work essential to positive stress experiences. Following an overview of approaches to stress at work, eustress and reflective practice, the paper explores how entrepreneurs experience the role of positive stress and reflective practice in their work and describes the reflective tools utilized by entrepreneurs in promoting eustress. The research process was designed to support reflective dialogue among the 21 Finnish entrepreneurs from different fields who participated in the study, with results based mainly on qualitative interviews. Nine of the interviewed entrepreneurs also kept a positive stress diary, including a three-day physiological measurement analysing their heartbeat variability. The findings suggest that positive stress and reflective practice are intertwined in the experiences of entrepreneurs and illustrate the role of reflective practice as a crucial toolset for promoting positive stress, comprising six reflective tools: studying oneself, changing one’s point of view, putting things into perspective, harnessing a feeling of trust, regulating resources and engaging in dialogue. Individual reflective capabilities vary, and a theory-driven division of reflective practice into individual, social and contextual dimensions is considered useful in understanding those differences. The research offers a starting point for exploring how eustress and reflective practice affect the well-being of entrepreneurs

  3. Randomness at the root of things 1: Random walks

    Science.gov (United States)

    Ogborn, Jon; Collins, Simon; Brown, Mick

    2003-09-01

    This is the first of a pair of articles about randomness in physics. In this article, we use some variations on the idea of a `random walk' to consider first the path of a particle in Brownian motion, and then the random variation to be expected in radioactive decay. The arguments are set in the context of the general importance of randomness both in physics and in everyday life. We think that the ideas could usefully form part of students' A-level work on random decay and quantum phenomena, as well as being good for their general education. In the second article we offer a novel and simple approach to Poisson sequences.

  4. Critical behaviour of nanocrystalline gadolinium: evidence for random uniaxial dipolar universality class

    International Nuclear Information System (INIS)

    Ferdinand, A; Probst, A-C; Birringer, R; Michels, A; Kaul, S N

    2014-01-01

    We report on how nanocrystal size affects the critical behaviour of the rare-earth metal Gd near the ferromagnetic-to-paramagnetic phase transition. The asymptotic critical behaviour of the coarse-grained polycrystalline sample (with an average crystallite size of L≅100 μm) is that of a (pure) uniaxial dipolar ferromagnet, as is the case with single crystal Gd, albeit the width of the asymptotic critical region (ACR) is reduced. As the grain size approaches ∼30 nm, the ACR is so narrow that it could not be accessed in the present experiments. Inaccessibly narrow ACR for L ∼ 30 nm and continuous increase in the width of the ACR as L decreases from 16 to 9.5 nm basically reflect a crossover to the random uniaxial dipolar fixed point caused by the quenched random exchange disorder prevalent at the internal interfaces (grain boundaries). (paper)

  5. Blocked Randomization with Randomly Selected Block Sizes

    Directory of Open Access Journals (Sweden)

    Jimmy Efird

    2010-12-01

    Full Text Available When planning a randomized clinical trial, careful consideration must be given to how participants are selected for various arms of a study. Selection and accidental bias may occur when participants are not assigned to study groups with equal probability. A simple random allocation scheme is a process by which each participant has equal likelihood of being assigned to treatment versus referent groups. However, by chance an unequal number of individuals may be assigned to each arm of the study and thus decrease the power to detect statistically significant differences between groups. Block randomization is a commonly used technique in clinical trial design to reduce bias and achieve balance in the allocation of participants to treatment arms, especially when the sample size is small. This method increases the probability that each arm will contain an equal number of individuals by sequencing participant assignments by block. Yet still, the allocation process may be predictable, for example, when the investigator is not blind and the block size is fixed. This paper provides an overview of blocked randomization and illustrates how to avoid selection bias by using random block sizes.

  6. Random Fields

    Science.gov (United States)

    Vanmarcke, Erik

    1983-03-01

    Random variation over space and time is one of the few attributes that might safely be predicted as characterizing almost any given complex system. Random fields or "distributed disorder systems" confront astronomers, physicists, geologists, meteorologists, biologists, and other natural scientists. They appear in the artifacts developed by electrical, mechanical, civil, and other engineers. They even underlie the processes of social and economic change. The purpose of this book is to bring together existing and new methodologies of random field theory and indicate how they can be applied to these diverse areas where a "deterministic treatment is inefficient and conventional statistics insufficient." Many new results and methods are included. After outlining the extent and characteristics of the random field approach, the book reviews the classical theory of multidimensional random processes and introduces basic probability concepts and methods in the random field context. It next gives a concise amount of the second-order analysis of homogeneous random fields, in both the space-time domain and the wave number-frequency domain. This is followed by a chapter on spectral moments and related measures of disorder and on level excursions and extremes of Gaussian and related random fields. After developing a new framework of analysis based on local averages of one-, two-, and n-dimensional processes, the book concludes with a chapter discussing ramifications in the important areas of estimation, prediction, and control. The mathematical prerequisite has been held to basic college-level calculus.

  7. Random walk of passive tracers among randomly moving obstacles

    OpenAIRE

    Gori, Matteo; Donato, Irene; Floriani, Elena; Nardecchia, Ilaria; Pettini, Marco

    2016-01-01

    Background: This study is mainly motivated by the need of understanding how the diffusion behaviour of a biomolecule (or even of a larger object) is affected by other moving macromolecules, organelles, and so on, inside a living cell, whence the possibility of understanding whether or not a randomly walking biomolecule is also subject to a long-range force field driving it to its target. Method: By means of the Continuous Time Random Walk (CTRW) technique the topic of random walk in random en...

  8. Reflectance spectra of subarctic lichens

    International Nuclear Information System (INIS)

    Petzold, D.E.; Goward, S.N.

    1988-01-01

    Lichens constitute a major portion of the ground cover of high latitude environments, but little has been reported concerning their in situ solar spectral reflectance properties. Knowledge of these properties is important for the interpretation of remotely sensed observations from high latitude regions, as well as in studies of high latitude ecology and energy balance climatology. The spectral reflectance of common boreal vascular plants is similar to that of vascular plants of the mid latitudes. The dominant lichens, in contrast, display variable reflectance patterns in visible wavelengths. The relative reflectance peak at 0.55 μm, common to green vegetation, is absent or indistinct in spectra of pervasive boreal forest and tundra lichens, despite the presence of chlorophyll in the inner algal cells. Lichens of the dominant genus, Cladina, display strong absorption of ultraviolet energy and short-wavelength blue light relative to their absorption in other visible wavelengths. Since the Cladinae dominate both the surface vegetation in open woodlands of the boreal forest and the low arctic tundra, their unusual spectral reflectance patterns will enable accurate monitoring of the boreal forest-tundra ecotone and detection of its vigor and movement in the future. (author)

  9. Reflectance spectra of subarctic lichens

    Science.gov (United States)

    Petzold, Donald E.; Goward, Samuel N.

    1988-01-01

    Lichens constitute a major portion of the ground cover of high latitude environments, but little has been reported concerning their in situ solar spectral reflectance properties. Knowledge of these properties is important for the interpretation of remotely sensed observations from high latitude regions, as well as in studies of high latitude ecology and energy balance climatology. The spectral reflectance of common boreal vascular plants is similar to that of vascular plants of the midlatitudes. The dominant lichens, in contrast, display variable reflectance patterns in visible wavelengths. The relative reflectance peak at 0.55 microns, common to green vegetation, is absent or indistinct in spectra of pervasive boreal forest and tundra lichens, despite the presence of chlorophyll in the inner algal cells. Lichens of the dominant genus, Cladina, display strong absorption of ultraviolet energy and short-wavelength blue light relative to their absorption in other visible wavelengths. Since the Cladinae dominate both the surface vegetation in open woodlands of the boreal forest and the low arctic tundra, their unusual spectral reflectance patterns will enable accurate monitoring of the boreal forest-tundra ecotone and detection of its vigor and movement in the future.

  10. L'evolution thermique de la matière organique des sédiments : applications d'une simulation mathématique. Potentiel pétrolier des bassins sédimentaires de reconstitution de l'histoire thermique des sédiments Thermal Evolution of Organic Matter in Sediments : Application of a Mathematical Simulation. Petrleum Potential of Sedimentary Basins and Reconstructing the Thermal History of Sediments

    Directory of Open Access Journals (Sweden)

    Tissot B.

    2006-11-01

    particular discusses the distribution of activation energies and its significance in relation to the composition of the kerogen. The other data required are the geological reconstruction of burial and the geothermal gradient. The reconstruction of ancient geothermics raises a special problem. By combining the measurement of vitrinite reflectance and the law of burial, a vitrinite évolution model con be used in most cases to reestablish the thermal history of the organic motter. This is of course of great interest for petroleum prospection, but its range of application goes far beyond this field and reaches all the way to problems of general geology such as geothermics, sediment diagenesis, global tectonics, etc.

  11. Pseudo-random number generator based on asymptotic deterministic randomness

    Science.gov (United States)

    Wang, Kai; Pei, Wenjiang; Xia, Haishan; Cheung, Yiu-ming

    2008-06-01

    A novel approach to generate the pseudorandom-bit sequence from the asymptotic deterministic randomness system is proposed in this Letter. We study the characteristic of multi-value correspondence of the asymptotic deterministic randomness constructed by the piecewise linear map and the noninvertible nonlinearity transform, and then give the discretized systems in the finite digitized state space. The statistic characteristics of the asymptotic deterministic randomness are investigated numerically, such as stationary probability density function and random-like behavior. Furthermore, we analyze the dynamics of the symbolic sequence. Both theoretical and experimental results show that the symbolic sequence of the asymptotic deterministic randomness possesses very good cryptographic properties, which improve the security of chaos based PRBGs and increase the resistance against entropy attacks and symbolic dynamics attacks.

  12. Pseudo-random number generator based on asymptotic deterministic randomness

    International Nuclear Information System (INIS)

    Wang Kai; Pei Wenjiang; Xia Haishan; Cheung Yiuming

    2008-01-01

    A novel approach to generate the pseudorandom-bit sequence from the asymptotic deterministic randomness system is proposed in this Letter. We study the characteristic of multi-value correspondence of the asymptotic deterministic randomness constructed by the piecewise linear map and the noninvertible nonlinearity transform, and then give the discretized systems in the finite digitized state space. The statistic characteristics of the asymptotic deterministic randomness are investigated numerically, such as stationary probability density function and random-like behavior. Furthermore, we analyze the dynamics of the symbolic sequence. Both theoretical and experimental results show that the symbolic sequence of the asymptotic deterministic randomness possesses very good cryptographic properties, which improve the security of chaos based PRBGs and increase the resistance against entropy attacks and symbolic dynamics attacks

  13. Daytime Water Detection Based on Sky Reflections

    Science.gov (United States)

    Rankin, Arturo; Matthies, Larry; Bellutta, Paolo

    2011-01-01

    A water body s surface can be modeled as a horizontal mirror. Water detection based on sky reflections and color variation are complementary. A reflection coefficient model suggests sky reflections dominate the color of water at ranges > 12 meters. Water detection based on sky reflections: (1) geometrically locates the pixel in the sky that is reflecting on a candidate water pixel on the ground (2) predicts if the ground pixel is water based on color similarity and local terrain features. Water detection has been integrated on XUVs.

  14. Toy models of crossed Andreev reflection

    International Nuclear Information System (INIS)

    Melin, R; Jirari, H; Peysson, S

    2003-01-01

    We propose toy models of crossed Andreev reflection in multiterminal hybrid structures containing out-of-equilibrium conductors. We apply the description to two possible experiments: (i) to a device containing a large quantum dot inserted in a crossed Andreev reflection circuit, and (ii) to a device containing an Aharonov-Bohm loop inserted in a crossed Andreev reflection circuit

  15. Solution Methods for Structures with Random Properties Subject to Random Excitation

    DEFF Research Database (Denmark)

    Köylüoglu, H. U.; Nielsen, Søren R. K.; Cakmak, A. S.

    This paper deals with the lower order statistical moments of the response of structures with random stiffness and random damping properties subject to random excitation. The arising stochastic differential equations (SDE) with random coefficients are solved by two methods, a second order...... the SDE with random coefficients with deterministic initial conditions to an equivalent nonlinear SDE with deterministic coefficient and random initial conditions. In both methods, the statistical moment equations are used. Hierarchy of statistical moments in the markovian approach is closed...... by the cumulant neglect closure method applied at the fourth order level....

  16. Structural properties of reflected Lévy processes

    DEFF Research Database (Denmark)

    Andersen, Lars Nørvang; Mandjes, Michel

    This paper considers a number of structural properties of reflected Lévy processes, where both one-sided reflection (at 0) and two-sided reflection (at both 0 and K > 0) are examined. With Vt being the position of the reflected process at time t, we focus on the analysis of ζ(t) := EVt and ξ(t) :...

  17. Strong Shock Propagating Over A Random Bed of Spherical Particles

    Science.gov (United States)

    Mehta, Yash; Salari, Kambiz; Jackson, Thomas L.; Balachandar, S.; Thakur, Siddharth

    2017-11-01

    The study of shock interaction with particles has been largely motivated because of its wide-ranging applications. The complex interaction between the compressible flow features, such as shock wave and expansion fan, and the dispersed phase makes this multi-phase flow very difficult to predict and control. In this talk we will be presenting results on fully resolved inviscid simulations of shock interaction with random bed of particles. One of the fascinating observations from these simulations are the flow field fluctuations due to the presence of randomly distributed particles. Rigorous averaging (Favre averaging) of the governing equations results in Reynolds stress like term, which can be classified as pseudo turbulence in this case. We have computed this ``Reynolds stress'' term along with individual fluctuations and the turbulent kinetic energy. Average pressure was also computed to characterize the strength of the transmitted and the reflected waves. This work was supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program.

  18. Infrared reflection properties and modelling of in situ reflection measurements on plasma-facing materials in Tore Supra

    International Nuclear Information System (INIS)

    Reichle, R; Desgranges, C; Faisse, F; Pocheau, C; Lasserre, J-P; Oelhoffen, F; Eupherte, L; Todeschini, M

    2009-01-01

    Tore Supra has-like ITER-reflecting internal surfaces, which can perturb the machine protection systems based on infrared (IR) thermography. To ameliorate this situation, we have measured and modelled in the 3-5 μm wavelength range the bi-directional reflection distribution function (BRDF) of wall material samples from Tore Supra and conducted in situ reflection measurements and simulated them with the CEA COSMOS code. BRDF results are presented for B 4 C and carbon fibre composite (CFC) tiles. The hemispherical integrated reflection ranges from 0.12 for the B 4 C sample to 0.39 for a CFC tile from the limiter erosion zone. In situ measurements of the IR reflection of a blackbody source off an ICRH and an LHCD antenna of Tore Supra are well reproduced by the simulation.

  19. Infrared reflection properties and modelling of in situ reflection measurements on plasma-facing materials in Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Reichle, R; Desgranges, C; Faisse, F; Pocheau, C [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Lasserre, J-P; Oelhoffen, F; Eupherte, L; Todeschini, M [CEA, DAM, CESTA, F-33114 Le Barp (France)

    2009-12-15

    Tore Supra has-like ITER-reflecting internal surfaces, which can perturb the machine protection systems based on infrared (IR) thermography. To ameliorate this situation, we have measured and modelled in the 3-5 {mu}m wavelength range the bi-directional reflection distribution function (BRDF) of wall material samples from Tore Supra and conducted in situ reflection measurements and simulated them with the CEA COSMOS code. BRDF results are presented for B{sub 4}C and carbon fibre composite (CFC) tiles. The hemispherical integrated reflection ranges from 0.12 for the B{sub 4}C sample to 0.39 for a CFC tile from the limiter erosion zone. In situ measurements of the IR reflection of a blackbody source off an ICRH and an LHCD antenna of Tore Supra are well reproduced by the simulation.

  20. Inadmissibility of Usual and Mixed Estimators of Two Ordered Gamma Scale Parameters Under Reflected Gamma Loss Function

    OpenAIRE

    Z. Meghnatisi; N. Nematollahi

    2009-01-01

    Let Xi1, · · · , Xini be a random sample from a gamma distribution with known shape parameter νi > 0 and unknown scale parameter βi > 0, i = 1, 2, satisfying 0 < β1 6 β2. We consider the class of mixed estimators for estimation of β1 and β2 under reflected gamma loss function. It has been shown that the minimum risk equivariant estimator of βi, i = 1, 2, which is admissible when no information on the ordering of parameters are given, is inadmissible and dominated by a cla...

  1. Relationships between data from Rock-Eval pyrolysis and proximate, ultimate, petrographic, and physical analyses of 142 diverse U.S. coal samples

    Science.gov (United States)

    Bostick, N.H.; Daws, T.A.

    1994-01-01

    Basic research on coal and oil shale led to automated pyrolysis analysis of petroleum source rocks; most widely used is the Rock-Eval equipment. In order to interpret Rock-Eval analyses in relation to traditional coal data, we analyzed 142 commercial coals with diverse rank, age, maceral and sulfur contents, for most regions of the United States. We compared the Rock-Eval data with traditional industrial coal data, including volatile matter, calorific value, hydrogen and oxygen content, free swelling index, and vitrinite reflectance. We found: (1) there is a close relationship between Tmax and vitrinite reflectance in the ranges 420-590??C Tmax and 0.4-3%Romax of most coals. (2) A close relationship between Tmax and volatile matter (%VM) extends through the entire sample range, including low-rank samples with 35-70% VM, a range where %VM is not considered to be a useful rank parameter. (3) TOC of medium- and high-rank coals is seriously under-measured by Rock-Eval; TOC of low-rank coals (less than 0.8%Romax) is close to "dry basis" carbon from ultimate analysis. (4) The direct relationships between oxygen index (OI) and %O and between hydrogen index (HI) and %H are clear, though only broadly defined. However, there is virtually no band of concentrated data points on the HI versus OI pseudo-Van Krevelen diagram comparable to the "development line" on the H/C versus O/C diagram. (5) There are systematic relationships between Rock-Eval and industrial coal parameters such as calorific value and FSI, but much standardization would be needed before Rock-Eval could find a place in the coal industry. Tests with blends of coal and quartz sand and with various loads of coal alone showed that the amount of organic matter in the Rock-Eval load greatly influences results. Total load in the crucible, if largely inert, plays a small role, however. Increasing absolute or relative coal content causes under-evaluation of Rock-Eval TOC and over-rating of hydrogen. Blends of several

  2. Thermal maturity patterns in Pennsylvanian coal-bearing rocks in Alabama, Tennessee, Kentucky, Virginia, West Virginia, Ohio, Maryland, and Pennsylvania: Chapter F.2 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

    Science.gov (United States)

    Ruppert, Leslie F.; Trippi, Michael H.; Hower, James C.; Grady, William C.; Levine, Jeffrey R.; Ruppert, Leslie F.; Ryder, Robert T.

    2014-01-01

    Thermal maturation patterns of Pennsylvanian strata in the Appalachian basin and part of the Black Warrior basin were determined by compiling previously published and unpublished percent-vitrinite-reflectance (%R0) measurements and preparing isograd maps on the basis of the measurements. The isograd values range from 0.6 %R0 in Ohio and the western side of the Eastern Kentucky coal field to 5.5 %R0 in the Southern field in the Pennsylvania Anthracite region, Schuylkill County, Pa. The vitrinite-reflectance values correspond to the American Society of Testing Materials (ASTM) coal-rank classes of high-volatile C bituminous to meta-anthracite, respectively. In general, the isograds show that thermal maturity patterns of Pennsylvanian coals within the Appalachian basin generally decrease from east to west. In the Black Warrior basin of Alabama, the isograds show a circular pattern with the highest values (greater than 1.6 %R0) centered in Jefferson County, Ala. Most of the observed patterns can be explained by variations in the depth of burial, variations in geothermal gradient, or a combination of both; however, there are at least four areas of higher ranking coal in the Appalachian basin that are difficult to explain by these two processes alone: (1) a set of west- to northwest-trending salients centered in Somerset, Cambria, and Fayette Counties, Pa.; (2) an elliptically shaped, northeast-trending area centered in southern West Virginia and western Virginia; (3) the Pennsylvania Anthracite region in eastern Pennsylvania; and (4) the eastern part of the Black Warrior coal field in Alabama. The areas of high-ranking coal in southwestern Pennsylvania, the Black Warrior coal field, and the Pennsylvania Anthracite region are interpreted here to represent areas of higher paleo-heat flow related to syntectonic movement of hot fluids towards the foreland associated with Alleghanian deformation. In addition to the higher heat flow from these fluids, the Pennsylvania

  3. Mineralogy and organic petrology of oil shales in the Sangkarewang Formation, Ombilin Basin, West Sumatra, Indonesia

    Energy Technology Data Exchange (ETDEWEB)

    Fatimah [School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052 (Australia)]|[Centre for Geological Resources, Department of Mines and Energy, Jalan Soekarno Hatta No. 444, Bandung 40254 (Indonesia); Ward, Colin R. [School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052 (Australia)

    2009-01-31

    The Ombilin Basin is filled by late Eocene to early Oligocene marginal fan deposits (Brani Formation) and lacustrine shales (Sangkarewang Formation), unconformably overlain by a late Oligocene to early Miocene fluvial sequence (Sawahlunto and Sawahtambang Formations) and capped by an early to mid-Miocene marine sequence (Ombilin Formation). Significant oil shale deposits occur in the Sangkarewang Formation, intercalated with thin laminated greenish-grey calcareous sandstones. X-ray diffraction shows that the sediments consist mainly of quartz, feldspar, carbonates and a range of clay minerals, together in some cases with minor proportions of sulphides, evaporites and zeolites. Feldspar and non-kaolinite clay minerals decrease up the sequence, relative to kaolinite, suggesting a changing sediment source as the basin was filled. Calcite, thought to be mainly of authigenic origin, is also more abundant in the middle and upper parts of the sequence. The organic matter in the oil shales of the sequence is dominated by liptinite macerals, particularly alginite (mainly lamalginite) and sporinite. Cutinite also occurs in some samples, along with resinite and traces of bituminite. The dominance of lamalginite in the liptinite components suggests that the material can be described as a lamosite. Samples from the Sangkarewang Formation have vitrinite reflectance values ranging between 0.37% and 0.55%. These are markedly lower than the vitrinite reflectance for coal from the overlying Sawahlunto Formation (0.68%), possibly due to suppression associated with the abundant liptinite in the oil shales. Fischer assay data on outcrop samples indicate that the oil yield is related to the organic carbon content. Correlations with XRD data show that, with one exception, the oil yield and organic carbon can also be correlated directly to the abundance of carbonate (calcite) and inversely to the abundance of quartz plus feldspar. This suggests that the abundance of algal material in the

  4. Reflections around Artefacts: Using a Deliberative Approach to Teaching Reflective Practices in Fashion Studies

    Science.gov (United States)

    Ryan, Michael; Brough, Dean

    2012-01-01

    While requiring students to think reflectively is a desirable teaching goal, it is often fraught with complexity and is sometimes poorly implemented in higher education. In this paper, we describe an approach to academic reflective practices that fitted a design subject in fashion education and was perceived as effective in enhancing student…

  5. Acute resistance exercise using free weights on aortic wave reflection characteristics.

    Science.gov (United States)

    Tai, Yu Lun; Gerhart, Hayden; Mayo, Xián; Kingsley, J Derek

    2018-01-01

    Aortic wave reflection characteristics such as the augmentation index (AIx), wasted left ventricular pressure energy (ΔE w ) and aortic haemodynamics, such as aortic systolic blood pressure (ASBP), strongly predict cardiovascular events. The effects of acute resistance exercise (ARE) using free-weight exercises on these characteristics are unknown. Therefore, we sought to determine the effects of acute free-weight resistance exercise on aortic wave reflection characteristics and aortic haemodynamics in resistance-trained individuals. Fifteen young, healthy resistance-trained (9 ± 3 years) individuals performed two randomized sessions consisting of an acute bout of free-weight resistance exercise (ARE) or a quiet control (CON). The ARE consisted of three sets of 10 repetitions at 75% one repetition maximum for squat, bench press and deadlift. In CON, the participants rested in the supine position for 30 min. Measurements were made at baseline before sessions and 10 min after sessions. A two-way ANOVA was used to compare the effects of condition across time. There were no significant interactions for aortic or brachial blood pressures. Compared to rest, there were significant increases in augmentation pressure (rest: 5·7 ± 3·0 mmHg; recovery: 10·4 ± 5·7 mmHg, P = 0·002), AIx (rest: 116·8 ± 4·2%; recovery: 123·2 ± 8·4%, P = 0·002), AIx normalized at 75 bpm (rest: 5·2 ± 7·6%; recovery: 27·3 ± 13·2%, Pfree-weight exercises may have no effect on aortic and brachial blood pressure but may significantly alter aortic wave reflection characteristics. © 2016 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  6. A Fast Reactive Power Optimization in Distribution Network Based on Large Random Matrix Theory and Data Analysis

    Directory of Open Access Journals (Sweden)

    Wanxing Sheng

    2016-05-01

    Full Text Available In this paper, a reactive power optimization method based on historical data is investigated to solve the dynamic reactive power optimization problem in distribution network. In order to reflect the variation of loads, network loads are represented in a form of random matrix. Load similarity (LS is defined to measure the degree of similarity between the loads in different days and the calculation method of the load similarity of load random matrix (LRM is presented. By calculating the load similarity between the forecasting random matrix and the random matrix of historical load, the historical reactive power optimization dispatching scheme that most matches the forecasting load can be found for reactive power control usage. The differences of daily load curves between working days and weekends in different seasons are considered in the proposed method. The proposed method is tested on a standard 14 nodes distribution network with three different types of load. The computational result demonstrates that the proposed method for reactive power optimization is fast, feasible and effective in distribution network.

  7. Large-area imaging reveals biologically driven non-random spatial patterns of corals at a remote reef

    Science.gov (United States)

    Edwards, Clinton B.; Eynaud, Yoan; Williams, Gareth J.; Pedersen, Nicole E.; Zgliczynski, Brian J.; Gleason, Arthur C. R.; Smith, Jennifer E.; Sandin, Stuart A.

    2017-12-01

    For sessile organisms such as reef-building corals, differences in the degree of dispersion of individuals across a landscape may result from important differences in life-history strategies or may reflect patterns of habitat availability. Descriptions of spatial patterns can thus be useful not only for the identification of key biological and physical mechanisms structuring an ecosystem, but also by providing the data necessary to generate and test ecological theory. Here, we used an in situ imaging technique to create large-area photomosaics of 16 plots at Palmyra Atoll, central Pacific, each covering 100 m2 of benthic habitat. We mapped the location of 44,008 coral colonies and identified each to the lowest taxonomic level possible. Using metrics of spatial dispersion, we tested for departures from spatial randomness. We also used targeted model fitting to explore candidate processes leading to differences in spatial patterns among taxa. Most taxa were clustered and the degree of clustering varied by taxon. A small number of taxa did not significantly depart from randomness and none revealed evidence of spatial uniformity. Importantly, taxa that readily fragment or tolerate stress through partial mortality were more clustered. With little exception, clustering patterns were consistent with models of fragmentation and dispersal limitation. In some taxa, dispersion was linearly related to abundance, suggesting density dependence of spatial patterning. The spatial patterns of stony corals are non-random and reflect fundamental life-history characteristics of the taxa, suggesting that the reef landscape may, in many cases, have important elements of spatial predictability.

  8. Validation of a spectral correction procedure for sun and sky reflections in above-water reflectance measurements.

    Science.gov (United States)

    Groetsch, Philipp M M; Gege, Peter; Simis, Stefan G H; Eleveld, Marieke A; Peters, Steef W M

    2017-08-07

    A three-component reflectance model (3C) is applied to above-water radiometric measurements to derive remote-sensing reflectance Rrs (λ). 3C provides a spectrally resolved offset Δ(λ) to correct for residual sun and sky radiance (Rayleigh- and aerosol-scattered) reflections on the water surface that were not represented by sky radiance measurements. 3C is validated with a data set of matching above- and below-water radiometric measurements collected in the Baltic Sea, and compared against a scalar offset correction Δ. Correction with Δ(λ) instead of Δ consistently reduced the (mean normalized root-mean-square) deviation between Rrs (λ) and reference reflectances to comparable levels for clear (Δ: 14.3 ± 2.5 %, Δ(λ): 8.2 ± 1.7 %), partly clouded (Δ: 15.4 ± 2.1 %, Δ(λ): 6.5 ± 1.4 %), and completely overcast (Δ: 10.8 ± 1.7 %, Δ(λ): 6.3 ± 1.8 %) sky conditions. The improvement was most pronounced under inhomogeneous sky conditions when measurements of sky radiance tend to be less representative of surface-reflected radiance. Accounting for both sun glint and sky reflections also relaxes constraints on measurement geometry, which was demonstrated based on a semi-continuous daytime data set recorded in a eutrophic freshwater lake in the Netherlands. Rrs (λ) that were derived throughout the day varied spectrally by less than 2 % relative standard deviation. Implications on measurement protocols are discussed. An open source software library for processing reflectance measurements was developed and is made publicly available.

  9. Model of bidirectional reflectance distribution function for metallic materials

    International Nuclear Information System (INIS)

    Wang Kai; Zhu Jing-Ping; Liu Hong; Hou Xun

    2016-01-01

    Based on the three-component assumption that the reflection is divided into specular reflection, directional diffuse reflection, and ideal diffuse reflection, a bidirectional reflectance distribution function (BRDF) model of metallic materials is presented. Compared with the two-component assumption that the reflection is composed of specular reflection and diffuse reflection, the three-component assumption divides the diffuse reflection into directional diffuse and ideal diffuse reflection. This model effectively resolves the problem that constant diffuse reflection leads to considerable error for metallic materials. Simulation and measurement results validate that this three-component BRDF model can improve the modeling accuracy significantly and describe the reflection properties in the hemisphere space precisely for the metallic materials. (paper)

  10. Model of bidirectional reflectance distribution function for metallic materials

    Science.gov (United States)

    Wang, Kai; Zhu, Jing-Ping; Liu, Hong; Hou, Xun

    2016-09-01

    Based on the three-component assumption that the reflection is divided into specular reflection, directional diffuse reflection, and ideal diffuse reflection, a bidirectional reflectance distribution function (BRDF) model of metallic materials is presented. Compared with the two-component assumption that the reflection is composed of specular reflection and diffuse reflection, the three-component assumption divides the diffuse reflection into directional diffuse and ideal diffuse reflection. This model effectively resolves the problem that constant diffuse reflection leads to considerable error for metallic materials. Simulation and measurement results validate that this three-component BRDF model can improve the modeling accuracy significantly and describe the reflection properties in the hemisphere space precisely for the metallic materials.

  11. A Study on Reflective Reciprocal Peer Coaching for Pre-Service Teachers: Change in Reflectivity

    Science.gov (United States)

    Gonen, S. Ipek Kuru

    2016-01-01

    Reflective practice is considered as an effective way for professional development in order to gain awareness of one's own teaching as well as to compete with the changing needs of the students. Especially in pre-service period, when pre-service teachers work cooperatively with their peers in a reciprocal fashion towards reflectivity, it has a…

  12. Blogging for Reflection: The Use of Online Journals to Engage Students in Reflective Learning

    Science.gov (United States)

    Muncy, James A.

    2014-01-01

    Reflective learning has long been studied in many disciplines. A primary way that reflective learning has been taught is through journaling. With the advent of e-learning, journaling has moved to the Web in the form of blogs. The current paper reviews the current state of journaling and blogging research with specific recommendations for marketing…

  13. Spatial analysis of "crazy quilts", a class of potentially random aesthetic artefacts.

    Directory of Open Access Journals (Sweden)

    Gesche Westphal-Fitch

    Full Text Available Human artefacts in general are highly structured and often display ordering principles such as translational, reflectional or rotational symmetry. In contrast, human artefacts that are intended to appear random and non symmetrical are very rare. Furthermore, many studies show that humans find it extremely difficult to recognize or reproduce truly random patterns or sequences. Here, we attempt to model two-dimensional decorative spatial patterns produced by humans that show no obvious order. "Crazy quilts" represent a historically important style of quilt making that became popular in the 1870s, and lasted about 50 years. Crazy quilts are unusual because unlike most human artefacts, they are specifically intended to appear haphazard and unstructured. We evaluate the degree to which this intention was achieved by using statistical techniques of spatial point pattern analysis to compare crazy quilts with regular quilts from the same region and era and to evaluate the fit of various random distributions to these two quilt classes. We found that the two quilt categories exhibit fundamentally different spatial characteristics: The patch areas of crazy quilts derive from a continuous random distribution, while area distributions of regular quilts consist of Gaussian mixtures. These Gaussian mixtures derive from regular pattern motifs that are repeated and we suggest that such a mixture is a distinctive signature of human-made visual patterns. In contrast, the distribution found in crazy quilts is shared with many other naturally occurring spatial patterns. Centroids of patches in the two quilt classes are spaced differently and in general, crazy quilts but not regular quilts are well-fitted by a random Strauss process. These results indicate that, within the constraints of the quilt format, Victorian quilters indeed achieved their goal of generating random structures.

  14. Spatial analysis of "crazy quilts", a class of potentially random aesthetic artefacts.

    Science.gov (United States)

    Westphal-Fitch, Gesche; Fitch, W Tecumseh

    2013-01-01

    Human artefacts in general are highly structured and often display ordering principles such as translational, reflectional or rotational symmetry. In contrast, human artefacts that are intended to appear random and non symmetrical are very rare. Furthermore, many studies show that humans find it extremely difficult to recognize or reproduce truly random patterns or sequences. Here, we attempt to model two-dimensional decorative spatial patterns produced by humans that show no obvious order. "Crazy quilts" represent a historically important style of quilt making that became popular in the 1870s, and lasted about 50 years. Crazy quilts are unusual because unlike most human artefacts, they are specifically intended to appear haphazard and unstructured. We evaluate the degree to which this intention was achieved by using statistical techniques of spatial point pattern analysis to compare crazy quilts with regular quilts from the same region and era and to evaluate the fit of various random distributions to these two quilt classes. We found that the two quilt categories exhibit fundamentally different spatial characteristics: The patch areas of crazy quilts derive from a continuous random distribution, while area distributions of regular quilts consist of Gaussian mixtures. These Gaussian mixtures derive from regular pattern motifs that are repeated and we suggest that such a mixture is a distinctive signature of human-made visual patterns. In contrast, the distribution found in crazy quilts is shared with many other naturally occurring spatial patterns. Centroids of patches in the two quilt classes are spaced differently and in general, crazy quilts but not regular quilts are well-fitted by a random Strauss process. These results indicate that, within the constraints of the quilt format, Victorian quilters indeed achieved their goal of generating random structures.

  15. Curvature of random walks and random polygons in confinement

    International Nuclear Information System (INIS)

    Diao, Y; Ernst, C; Montemayor, A; Ziegler, U

    2013-01-01

    The purpose of this paper is to study the curvature of equilateral random walks and polygons that are confined in a sphere. Curvature is one of several basic geometric properties that can be used to describe random walks and polygons. We show that confinement affects curvature quite strongly, and in the limit case where the confinement diameter equals the edge length the unconfined expected curvature value doubles from π/2 to π. To study curvature a simple model of an equilateral random walk in spherical confinement in dimensions 2 and 3 is introduced. For this simple model we derive explicit integral expressions for the expected value of the total curvature in both dimensions. These expressions are functions that depend only on the radius R of the confinement sphere. We then show that the values obtained by numeric integration of these expressions agrees with numerical average curvature estimates obtained from simulations of random walks. Finally, we compare the confinement effect on curvature of random walks with random polygons. (paper)

  16. Applicability of the condensed-random-walk Monte Carlo method at low energies in high-Z materials

    International Nuclear Information System (INIS)

    Berger, Martin J.

    1998-01-01

    The predictions of several Monte Carlo codes were compared with each other and with experimental results pertaining to the penetration of through gold foils of electrons incident with energies from 128 to 8 keV. The main purpose was to demonstrate that reflection and transmission coefficients, for number and energy, can be estimated reliably with a simple Monte Carlo code based on the condensed-random-walk and continuous-slowing-down approximations

  17. Random magnetism

    International Nuclear Information System (INIS)

    Tahir-Kheli, R.A.

    1975-01-01

    A few simple problems relating to random magnetic systems are presented. Translational symmetry, only on the macroscopic scale, is assumed for these systems. A random set of parameters, on the microscopic scale, for the various regions of these systems is also assumed. A probability distribution for randomness is obeyed. Knowledge of the form of these probability distributions, is assumed in all cases [pt

  18. Reflective Healthcare Systems: micro-Cycle of Self-Reflection to empower users

    Directory of Open Access Journals (Sweden)

    Juan Jimenez Garcia

    2015-02-01

    Full Text Available Data collection and reflection are considered an integrated process in Personal Informatics to help users take action towards changing behaviour. Facilitating the collection and visualization of large data sets has been a major technical challenge to guarantee meaningful and effortless information to users. However this focus results in a passive involvement of users in these stages, creating distance between the user and their data, thus hindering proper understanding of people’s current behaviours. Designing for active participation may aid users in forming a closer bond to data. Going beyond the support of visualization of performance data, this paper introduces ESTHER 1.3 as an approach to facilitate active mini cycles of self-reflection (mCR by means of in-situ self-reporting mechanisms. ESTHER 1.3 is presented as an implementation of this mini cycles in the context of physical activity and knowledge workers. A field study evaluation of 23 days with 5 users shows the opportunities of the mini cycles to engage people in deeper reflection and to support them to perform better-informed actions, as well as the challenges in the implementation of mCR elements for a specific context.

  19. The effect of reflective writing interventions on the critical thinking skills and dispositions of baccalaureate nursing students.

    Science.gov (United States)

    Naber, Jessica; Wyatt, Tami H

    2014-01-01

    The importance of critical thinking is well-documented by the American Association of Colleges of Nursing and the National League for Nursing. Reflective writing is often used to increase understanding and analytical ability. The lack of empirical evidence about the effect of reflective writing interventions on critical thinking supports the examination of this concept. Study objectives were: This study used an experimental, pretest-posttest design. The setting was two schools of nursing at universities in the southern United States. The convenience sample included 70 fourth-semester students in baccalaureate nursing programs. Randomly assigned control and experimental groups completed the California Critical Thinking Skills Test (CCTST) and the California Critical Thinking Dispositions Inventory Test (CCTDI). The experimental group completed six reflective writing assignments. Both groups completed the two tests again. Results showed that the experimental group had a significant increase (p=0.03) on the truthseeking subscale of the CCTDI when compared to the control group. The experimental group's scores increased on four CCTST subscales and were higher than the control group's on three CCTST subscales. The results of this study make it imperative for nursing schools to consider including reflective writing-especially assignments based on Paul's (1993) model-in nursing courses. If future studies, testing over longer periods of time, show significant increases in critical thinking, those interventions could be incorporated into nursing curriculum and change the way nurse educators evaluate students. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. A climatology of visible surface reflectance spectra

    International Nuclear Information System (INIS)

    Zoogman, Peter; Liu, Xiong; Chance, Kelly; Sun, Qingsong; Schaaf, Crystal; Mahr, Tobias; Wagner, Thomas

    2016-01-01

    We present a high spectral resolution climatology of visible surface reflectance as a function of wavelength for use in satellite measurements of ozone and other atmospheric species. The Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument is planned to measure backscattered solar radiation in the 290–740 nm range, including the ultraviolet and visible Chappuis ozone bands. Observation in the weak Chappuis band takes advantage of the relative transparency of the atmosphere in the visible to achieve sensitivity to near-surface ozone. However, due to the weakness of the ozone absorption features this measurement is more sensitive to errors in visible surface reflectance, which is highly variable. We utilize reflectance measurements of individual plant, man-made, and other surface types to calculate the primary modes of variability of visible surface reflectance at a high spectral resolution, comparable to that of TEMPO (0.6 nm). Using the Moderate-resolution Imaging Spectroradiometer (MODIS) Bidirection Reflectance Distribution Function (BRDF)/albedo product and our derived primary modes we construct a high spatial resolution climatology of wavelength-dependent surface reflectance over all viewing scenes and geometries. The Global Ozone Monitoring Experiment–2 (GOME-2) Lambertian Equivalent Reflectance (LER) product provides complementary information over water and snow scenes. Preliminary results using this approach in multispectral ultraviolet+visible ozone retrievals from the GOME-2 instrument show significant improvement to the fitting residuals over vegetated scenes. - Highlights: • Our goals was visible surface reflectance for satellite trace gas measurements. • Captured the range of surface reflectance spectra through EOF analysis. • Used satellite surface reflectance products for each given scene to anchor EOFs. • Generated a climatology of time/geometry dependent surface reflectance spectra. • Demonstrated potential to

  1. Neutron reflectivity

    Directory of Open Access Journals (Sweden)

    Cousin Fabrice

    2015-01-01

    Full Text Available The specular neutron reflectivity is a technique enabling the measurement of neutron scattering length density profile perpendicular to the plane of a surface or an interface, and thereby the profile of chemical composition. The characteristic sizes that are probed range from around 5 Å up 5000 Å. It is a scattering technique that averages information on the entire surface and it is therefore not possible to obtain information within the plane of the interface. The specific properties of neutrons (possibility of tuning the contrast by isotopic substitution, sensitivity to magnetism, negligible absorption, low energy of the incident neutrons makes it particularly interesting in the fields of soft matter, biophysics and magnetic thin films. This course is a basic introduction to the technique and does not address the magnetic reflectivity. It is composed of three parts describing respectively its principle and its formalism, the experimental aspects of the method (spectrometers, samples and two examples related to the materials for energy.

  2. New insights on the maturity distribution and shale gas potential of the Lower Saxony Basin, NW-Germany

    Energy Technology Data Exchange (ETDEWEB)

    Bruns, B.; Littke, R. [RWTH Aachen Univ. (Germany). Energy and Mineral Resources Group (EMR); Di Primio, R. [Deutsches GeoForchungsZentrum (GFZ), Potsdam (Germany). Sektion 4.3 - Organische Geochemie; Berner, U. [Bundesanstalt fuer Geowissenschaften und Rohstoffe (BGR), Hannover (Germany)

    2013-08-01

    Due to its economic relevance the Lower Saxony Basin has been intensively investigated. Consequently it can be regarded as a well-known example of a sedimentary basin that experienced strong inversion. Oil and gas source rocks of economical importance comprise Upper Carboniferous coals as well as Jurassic (Toarcian/Posidonia Shale) and Cretaceous (Berriasian/Wealden) marls. Many basin modeling projects have addressed this area but until now the tectonic and maturation history as well as the petroleum system evolution has not been evaluated in a high-resolution 3D model. Therefore, a fully integrated 3D high-resolution numerical petroleum system model was developed incorporating the Lower Saxony Basin and major parts of the Pompeckj Block, and Muensterland Basin. The burial and maturation history has been reconstructed calibrated by large amounts of vitrinite reflectance and downhole temperature data enabling the output of erosion and maturity distribution maps of superior quality. (orig.)

  3. Shock Interaction with Random Spherical Particle Beds

    Science.gov (United States)

    Neal, Chris; Mehta, Yash; Salari, Kambiz; Jackson, Thomas L.; Balachandar, S. "Bala"; Thakur, Siddharth

    2016-11-01

    In this talk we present results on fully resolved simulations of shock interaction with randomly distributed bed of particles. Multiple simulations were carried out by varying the number of particles to isolate the effect of volume fraction. Major focus of these simulations was to understand 1) the effect of the shockwave and volume fraction on the forces experienced by the particles, 2) the effect of particles on the shock wave, and 3) fluid mediated particle-particle interactions. Peak drag force for particles at different volume fractions show a downward trend as the depth of the bed increased. This can be attributed to dissipation of energy as the shockwave travels through the bed of particles. One of the fascinating observations from these simulations was the fluctuations in different quantities due to presence of multiple particles and their random distribution. These are large simulations with hundreds of particles resulting in large amount of data. We present statistical analysis of the data and make relevant observations. Average pressure in the computational domain is computed to characterize the strengths of the reflected and transmitted waves. We also present flow field contour plots to support our observations. U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

  4. Ethical reflection and psychotherapy.

    Science.gov (United States)

    Vyskocilová, Jana; Prasko, Jan

    2013-01-01

    Theories of ethics and ethical reflection may be applied to both theory and practice in psychotherapy. There is a natural affinity between ethics and psychotherapy. Psychotherapy practice is concerned with human problems, dilemmas and emotions related to both one's own and other people's values. Ethics is also concerned with dilemmas in human thinking and with how these dilemmas reflect other individuals' values. Philosophical reflection itself is not a sufficient basis for the ethics of psychotherapy but it may aid in exploring attitudes related to psychotherapy, psychiatry and health care. PubMed, Web of Science and Scopus databases were searched for articles containing the keywords "psychotherapy", "ethics", "therapeutic relationship" and "supervision". The search was conducted by repeating the terms in various combinations without language or time restrictions. Also included were data from monographs cited in reviews. The resulting text is a review with conclusions concerning ethical aspects of psychotherapy. The ability to behave altruistically, sense for justice and reciprocity and mutual help are likely to be genetically determined as dispositions to be later developed by upbringing or to be formed or deformed by upbringing. Early experiences lead to formation of ethical attitudes which are internalized and then applied to both one's own and other people's behavior. Altruistic behavior has a strong impact on an individual's health and its acceptance may positively influence the pathophysiological mechanisms underlying numerous diseases. Ethical theory and reflection, however, may be applied to both theory and practice of psychotherapy in a conscious, targeted and thoughtful manner. In everyday practice, psychotherapists and organizations must necessarily deal with conscious conflicts between therapeutic possibilities, clients' wishes, their own as well as clients' ideas and the real world. Understanding one's own motives in therapy is one of the aims of a

  5. High-accuracy self-mixing interferometer based on multiple reflections using a simple external reflecting mirror

    Science.gov (United States)

    Wang, Xiu-lin; Wei, Zheng; Wang, Rui; Huang, Wen-cai

    2018-05-01

    A self-mixing interferometer (SMI) with resolution twenty times higher than that of a conventional interferometer is developed by multiple reflections. Only by employing a simple external reflecting mirror, the multiple-pass optical configuration can be constructed. The advantage of the configuration is simple and easy to make the light re-injected back into the laser cavity. Theoretical analysis shows that the resolution of measurement is scalable by adjusting the number of reflections. The experiment shows that the proposed method has the optical resolution of approximate λ/40. The influence of displacement sensitivity gain ( G) is further analyzed and discussed in practical experiments.

  6. Seasonal trends in separability of leaf reflectance spectra for Ailanthus altissima and four other tree species

    Science.gov (United States)

    Burkholder, Aaron

    This project investigated the spectral separability of the invasive species Ailanthus altissima, commonly called tree of heaven, and four other native species. Leaves were collected from Ailanthus and four native tree species from May 13 through August 24, 2008, and spectral reflectance factor measurements were gathered for each tree using an ASD (Boulder, Colorado) FieldSpec Pro full-range spectroradiometer. The original data covered the range from 350-2500 nm, with one reflectance measurement collected per one nm wavelength. To reduce dimensionality, the measurements were resampled to the actual resolution of the spectrometer's sensors, and regions of atmospheric absorption were removed. Continuum removal was performed on the reflectance data, resulting in a second dataset. For both the reflectance and continuum removed datasets, least angle regression (LARS) and random forest classification were used to identify a single set of optimal wavelengths across all sampled dates, a set of optimal wavelengths for each date, and the dates for which Ailanthus is most separable from other species. It was found that classification accuracy varies both with dates and bands used. Contrary to expectations that early spring would provide the best separability, the lowest classification error was observed on July 22 for the reflectance data, and on May 13, July 11 and August 1 for the continuum removed data. This suggests that July and August are also potentially good months for species differentiation. Applying continuum removal in many cases reduced classification error, although not consistently. Band selection seems to be more important for reflectance data in that it results in greater improvement in classification accuracy, and LARS appears to be an effective band selection tool. The optimal spectral bands were selected from across the spectrum, often with bands from the blue (401-431 nm), NIR (1115 nm) and SWIR (1985-1995 nm), suggesting that hyperspectral sensors with

  7. Coal petrology of coal seams from the Leao-Butia Coalfield, Lower Permian of the Parana Basin, Brazil - Implications for coal facies interpretations

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.B. [Laboratorio de Oceanografia Geologica, Departamento de Geociencias, Fundacao Universidade Federal do Rio Grande, FURG, Av. Italia km 08, Campus Carreiros, 96201-900, Rio Grande, RS (Brazil); Kalkreuth, W.; Holz, M. [Instituto de Geociencias, UFRGS, Av. Bento Goncalves, 9500 91501-970 Porto Alegre, RS (Brazil)

    2008-02-01

    In the Leao-Butia Coalfield, Rio Grande do Sul the coal seams occur in the Rio Bonito Formation, Guata Group, Tubarao Supergroup of the Parana Basin, Brazil and are of Permian (Artinskian-Kungurian) age. This study is the first detailed investigation on the coal petrographic characterization of the coal-bearing sequence in relation to the depositional settings of the precursor mires, both in terms of whole seam characterization and in-seam variations. The study is based on the analyses of nine coal seams (I2, CI, L4, L3, L2, L1, S3, S2, S1), which were selected from core of borehole D-193, Leao-Butia and represent the entire coal-bearing sequence. The interpretation of coal facies and depositional environment is based on lithotype, maceral and microlithotype analyses using different facies-critical petrographic indices, which were displayed in coal facies diagrams. The seams are characterized by the predominance of dull lithotypes (dull, banded dull). The dullness of the coal is attributed to relatively high mineral matter, inertinite and liptinite contents. The petrographic composition is dominated by vitrinite (28-70 vol.% mmf) and inertinite (> 30 vol.% mmf) groups. Liptinite contents range from 7 to 30 vol.% (mmf) and mineral matter from 4-30 vol.%. Microlithotypes associations are dominated by vitrite, duroclarite, carbominerite and inertite. It is suggested that the observed vertical variations in petrographic characteristics (lithotypes, microlithotypes, macerals, vitrinite reflectance) were controlled by groundwater level fluctuations in the ancient mires due to different accommodation/peat accumulation rates. Correlation of the borehole strata with the general sequence-stratigraphical setting suggests that the alluvial fan system and the coal-bearing mudstone succession are linked to a late transgressive systems tract of sequence 2. Based on average compositional values obtained from coal facies diagrams, a deposition in a limno-telmatic to limnic coal

  8. Probability, random variables, and random processes theory and signal processing applications

    CERN Document Server

    Shynk, John J

    2012-01-01

    Probability, Random Variables, and Random Processes is a comprehensive textbook on probability theory for engineers that provides a more rigorous mathematical framework than is usually encountered in undergraduate courses. It is intended for first-year graduate students who have some familiarity with probability and random variables, though not necessarily of random processes and systems that operate on random signals. It is also appropriate for advanced undergraduate students who have a strong mathematical background. The book has the following features: Several app

  9. Global Explorers Journaling and Reflection Initiative

    Directory of Open Access Journals (Sweden)

    John Bennion

    2016-12-01

    Full Text Available Research suggests that journaling will increase reflection and improve program outcomes (Bain, et al, 1999; Duerden, et al, 2012 This study involved a partnership with a non-profit, Global Explorers (GEx, which provides international immersion experiences for youth. Their programs are designed to teach youth participants principles of leadership, environmental awareness, service, and science. This study, which tested whether teaching journaling techniques to youth program facilitators would have a positive impact on participant outcomes, addressed the following hypotheses: 1 Greater training in reflective thinking among participants would be associated with higher outcome scores, and 2 Participants in the intervention group (facilitators trained in journaling pedagogy would show greater increases in reflective thinking than comparison group members. Results based on participant self-assessment were significant in testing the first hypothesis; reflective thinking is positively associated with outcome measures, but the intervention group did not show increases in reflective thinking.

  10. Validating the Persian Version of Reflective Thinking Questionnaire and Probing Iranian University Students' Reflective Thinking and Academic Achievement

    Science.gov (United States)

    Ghanizadeh, Afsaneh; Jahedizadeh, Safoura

    2017-01-01

    Scholars in higher education deem reflective thinking as integral to the development of professional disciplinary practices. One of the major issues in studying reflective thinking pivots around its conceptualization and assessment. Over the years, researchers have used several methods and scales to measure reflective thinking. One of the most…

  11. Systematic random sampling of the comet assay.

    Science.gov (United States)

    McArt, Darragh G; Wasson, Gillian R; McKerr, George; Saetzler, Kurt; Reed, Matt; Howard, C Vyvyan

    2009-07-01

    The comet assay is a technique used to quantify DNA damage and repair at a cellular level. In the assay, cells are embedded in agarose and the cellular content is stripped away leaving only the DNA trapped in an agarose cavity which can then be electrophoresed. The damaged DNA can enter the agarose and migrate while the undamaged DNA cannot and is retained. DNA damage is measured as the proportion of the migratory 'tail' DNA compared to the total DNA in the cell. The fundamental basis of these arbitrary values is obtained in the comet acquisition phase using fluorescence microscopy with a stoichiometric stain in tandem with image analysis software. Current methods deployed in such an acquisition are expected to be both objectively and randomly obtained. In this paper we examine the 'randomness' of the acquisition phase and suggest an alternative method that offers both objective and unbiased comet selection. In order to achieve this, we have adopted a survey sampling approach widely used in stereology, which offers a method of systematic random sampling (SRS). This is desirable as it offers an impartial and reproducible method of comet analysis that can be used both manually or automated. By making use of an unbiased sampling frame and using microscope verniers, we are able to increase the precision of estimates of DNA damage. Results obtained from a multiple-user pooled variation experiment showed that the SRS technique attained a lower variability than that of the traditional approach. The analysis of a single user with repetition experiment showed greater individual variances while not being detrimental to overall averages. This would suggest that the SRS method offers a better reflection of DNA damage for a given slide and also offers better user reproducibility.

  12. Ethical Reflections on Becoming Teachers

    Science.gov (United States)

    Joseph, Pamela Bolotin

    2016-01-01

    This study analyzes narratives written in a culminating graduate seminar on reflective practice by 36 new secondary teachers who were asked to consider their moral beliefs, moral values and system of ethics as they reflected on their recent student teaching experiences. The findings explore how the participants depicted their constructed moral…

  13. Supporting Teacher Reflection through Online Discussion

    Directory of Open Access Journals (Sweden)

    Jiening Ruan

    2011-12-01

    Full Text Available The purpose of this case study was to investigate online discussion as a means to promote critical reflection. The study was conducted during a semester-long graduate course on issues related to literacy instructional strategies. The participants in the study were four reading education candidates. During the semester they participated in online discussion about course readings and reflected on their own teaching experiences. The data sources were the online discussion postings, responses to questionnaires, and interviews. The results suggest that technology-mediated discussion strengthens the learning community, facilitates sharing of professional experience among participants, and enhances teacher reflection. The results also point to the multi-faceted nature of teacher reflection.

  14. Dynamic approach to space and habitat use based on biased random bridges.

    Directory of Open Access Journals (Sweden)

    Simon Benhamou

    Full Text Available BACKGROUND: Although habitat use reflects a dynamic process, most studies assess habitat use statically as if an animal's successively recorded locations reflected a point rather than a movement process. By relying on the activity time between successive locations instead of the local density of individual locations, movement-based methods can substantially improve the biological relevance of utilization distribution (UD estimates (i.e. the relative frequencies with which an animal uses the various areas of its home range, HR. One such method rests on Brownian bridges (BBs. Its theoretical foundation (purely and constantly diffusive movements is paradoxically inconsistent with both HR settlement and habitat selection. An alternative involves movement-based kernel density estimation (MKDE through location interpolation, which may be applied to various movement behaviours but lacks a sound theoretical basis. METHODOLOGY/PRINCIPAL FINDINGS: I introduce the concept of a biased random (advective-diffusive bridge (BRB and show that the MKDE method is a practical means to estimate UDs based on simplified (isotropically diffusive BRBs. The equation governing BRBs is constrained by the maximum delay between successive relocations warranting constant within-bridge advection (allowed to vary between bridges but remains otherwise similar to the BB equation. Despite its theoretical inconsistencies, the BB method can therefore be applied to animals that regularly reorientate within their HRs and adapt their movements to the habitats crossed, provided that they were relocated with a high enough frequency. CONCLUSIONS/SIGNIFICANCE: Biased random walks can approximate various movement types at short times from a given relocation. Their simplified form constitutes an effective trade-off between too simple, unrealistic movement models, such as Brownian motion, and more sophisticated and realistic ones, such as biased correlated random walks (BCRWs, which are too

  15. Insight in schizophrenia: involvement of self-reflection networks?

    Science.gov (United States)

    van der Meer, Lisette; de Vos, Annerieke E; Stiekema, Annemarie P M; Pijnenborg, Gerdina H M; van Tol, Marie-José; Nolen, Willem A; David, Anthony S; Aleman, André

    2013-11-01

    Impaired insight is a common feature in psychosis and an important predictor of variables such as functional outcome, prognosis, and treatment adherence. A cognitive process that may underlie insight in psychosis is self-reflection, or the conscious evaluation of one's traits and characteristics. The current study aims to investigate the neural correlates of self-reflective processing and its relationship with insight in schizophrenia. Forty-seven schizophrenia patients and 21 healthy controls performed a self-reflection task in a functional magnetic resonance imaging (fMRI) scanner. The tasks comprised a self-reflection, close other-reflection, and a semantic (baseline) condition. Insight scores were obtained with the Schedule of Assessment of Insight Expanded. In addition, cognitive insight scores were obtained (Beck Cognitive Insight Scale [BCIS]). Schizophrenia patients demonstrated less activation in the posterior cingulate cortex in the self- and other-reflection conditions and less activation in the precuneus in the other-reflection condition compared with healthy controls. Better insight was associated with greater response in the inferior frontal gyrus, anterior insula, and inferior parietal lobule during self-reflection. In addition, better cognitive insight was associated with higher activation in ventromedial prefrontal cortex during self-reflection. In the current study, evidence for a relationship between self-reflection and insight in patients with schizophrenia was found in brain areas related to self-reflection, self/other distinction and source attribution. The findings support the rationale for a treatment that is currently under evaluation, which attempts to increase insight by enhancing self-reflection.

  16. Self-Reflection

    DEFF Research Database (Denmark)

    Fausing, Bent

    2018-01-01

    Reflecting has a double meaning, mirroring and thinking. The seminar will investigate how these two meanings intervene in each other. As we perceive we are already in pre-refectory state, and thinking involves a lot of not only thoughts, but also of senses and sensing, wherefrom our thoughts star...

  17. Suppression of Specular Reflections by Metasurface with Engineered Nonuniform Distribution of Reflection Phase

    Directory of Open Access Journals (Sweden)

    Xin Mi Yang

    2015-01-01

    Full Text Available We make preliminary investigations on a new approach to reducing radar cross section (RCS of conducting objects. This approach employs novel planar metasurfaces characterizing nonuniform distribution of reflection phase. The operation principle of this approach and the design rule of the associated metasurfaces are explained using a simplified theoretical model. We then present a design example of such metasurfaces, in which three-layer stacked square patches with variable sizes are utilized as the reflecting elements. The proposed RCS-reduction approach is verified by both numerical simulations and measurements on the example, under the assumption of normal plane wave incidence. It is observed that, in a fairly wide frequency band (from 3.6 to 5.5 GHz, the presented example is capable of suppressing the specular reflections of conducting plates significantly (by more than 7 dB for two orthogonal incident polarizations.

  18. A random number generator for continuous random variables

    Science.gov (United States)

    Guerra, V. M.; Tapia, R. A.; Thompson, J. R.

    1972-01-01

    A FORTRAN 4 routine is given which may be used to generate random observations of a continuous real valued random variable. Normal distribution of F(x), X, E(akimas), and E(linear) is presented in tabular form.

  19. Detection of the incipient oxidation of coal by petrographic techniques

    CSIR Research Space (South Africa)

    Kruszewska, KJ

    1996-05-01

    Full Text Available Two petrographic methods, namely long-wave fluorescence intensity measurements and a vitrinite elasticity index were developed and used to detect incipient oxidation in coals subjected to simulated weathering conditions. The two methods are based...

  20. Unmanned aerial system nadir reflectance and MODIS nadir BRDF-adjusted surface reflectances intercompared over Greenland

    Science.gov (United States)

    Faulkner Burkhart, John; Kylling, Arve; Schaaf, Crystal B.; Wang, Zhuosen; Bogren, Wiley; Storvold, Rune; Solbø, Stian; Pedersen, Christina A.; Gerland, Sebastian

    2017-07-01

    Albedo is a fundamental parameter in earth sciences, and many analyses utilize the Moderate Resolution Imaging Spectroradiometer (MODIS) bidirectional reflectance distribution function (BRDF)/albedo (MCD43) algorithms. While derivative albedo products have been evaluated over Greenland, we present a novel, direct comparison with nadir surface reflectance collected from an unmanned aerial system (UAS). The UAS was flown from Summit, Greenland, on 210 km transects coincident with the MODIS sensor overpass on board the Aqua and Terra satellites on 5 and 6 August 2010. Clear-sky acquisitions were available from the overpasses within 2 h of the UAS flights. The UAS was equipped with upward- and downward-looking spectrometers (300-920 nm) with a spectral resolution of 10 nm, allowing for direct integration into the MODIS bands 1, 3, and 4. The data provide a unique opportunity to directly compare UAS nadir reflectance with the MODIS nadir BRDF-adjusted surface reflectance (NBAR) products. The data show UAS measurements are slightly higher than the MODIS NBARs for all bands but agree within their stated uncertainties. Differences in variability are observed as expected due to different footprints of the platforms. The UAS data demonstrate potentially large sub-pixel variability of MODIS reflectance products and the potential to explore this variability using the UAS as a platform. It is also found that, even at the low elevations flown typically by a UAS, reflectance measurements may be influenced by haze if present at and/or below the flight altitude of the UAS. This impact could explain some differences between data from the two platforms and should be considered in any use of airborne platforms.

  1. Reflective teaching of medical communication skills with DiViDU: assessing the level of student reflection on recorded consultations with simulated patients.

    Science.gov (United States)

    Hulsman, R L; Harmsen, A B; Fabriek, M

    2009-02-01

    Acquisition of effective, goal-oriented communication skills requires both practicing skills and reflective thinking. Reflection is a cyclic process of perceiving and analysing communication behaviour in terms of goals and effects and designing improved actions. Based on Korthagen's ALACT reflection model, communication training on history taking was designed. Objectives were to develop rating criteria for assessment of the students' level of reflection and to collect student evaluations of the reflective cycle components in the communication training. All second year medical students recorded a consultation with a simulated patient. In DiViDU, a web-based ICT program, students reviewed the video, identified and marked three key events, attached written reflections and provided peer-feedback. Students' written reflections were rated on four reflection categories. A reflection-level score was based on a frequency count of the number of categories used over three reflections. Students filled out an evaluation questionnaire on components of the communication training. Data were analyzed of 304 (90.6%) students. The four reflection categories Observations, Motives, Effects and Goals of behaviour were used in 7-38%. Most students phrased undirected questions for improvement (93%). The average reflection score was 2.1 (S.D. 2.0). All training components were considered instructive. Acting was preferred most. Reviewing video was considered instructive. Self-reflection was considered more difficult than providing written feedback to the reflections of peers. Reflection on communication behaviour can be systematically implemented and measured in a structured way. Reflection levels were low, probably indicating a limited notion of goal-oriented attributes of communication skills. Early introduction of critical self-reflection facilitates acceptance of an important ability for physicians for continued life-long learning and becoming mindful practitioners.

  2. Near-peer role modeling: Can fourth-year medical students, recognized for their humanism, enhance reflection among second-year students in a physical diagnosis course?

    Directory of Open Access Journals (Sweden)

    Mimi McEvoy

    2016-09-01

    Full Text Available Introduction: Humanism is cultivated through reflection and self-awareness. We aimed to employ fourth-year medical students, recognized for their humanism, to facilitate reflective sessions for second-year medical students with the intention of positively influencing reflective process toward humanistic development. Methods/Analysis: A total of 186 students were randomly assigned to one of three comparison arms: eight groups of eight students (64 students were facilitated by a fourth-year student who was a Gold Humanism Honor Society member (GHHS; eight groups (64 students by a volunteer non-GHHS student; and seven groups (58 students were non-facilitated. Before sessions, second-year students set learning goals concerning interactions with patients; fourth-year students received training materials on facilitation. Groups met twice during their 10 clinical site visits. At the last session, students completed a reflective assignment on their goal progress. Comparative mixed method analyses were conducted among the three comparison arms on reflection (reflective score on in-session assignment and session satisfaction (survey in addition to a thematic analysis of responses on the in-session assignment. Results: We found significant differences among all three comparison arms on students’ reflective scores (p=0.0003 and satisfaction (p=0.0001. T-tests comparing GHHS- and non-GHHS-facilitated groups showed significantly higher mean reflective scores for GHHS-facilitated groups (p=0.033; there were no differences on session satisfaction. Thematic analysis of students’ reflections showed attempts at self-examination, but lacked depth in addressing emotions. There was a common focus on achieving comfort and confidence in clinical skills performance. Discussion/Conclusions: Near peers, recognized for their humanism, demonstrated significant influence in deepening medical students’ reflections surrounding patient interactions or humanistic

  3. Black Tea Lowers Blood Pressure and Wave Reflections in Fasted and Postprandial Conditions in Hypertensive Patients: A Randomised Study

    Directory of Open Access Journals (Sweden)

    Davide Grassi

    2015-02-01

    Full Text Available Hypertension and arterial stiffening are independent predictors of cardiovascular mortality. Flavonoids may exert some vascular protection. We investigated the effects of black tea on blood pressure (BP and wave reflections before and after fat load in hypertensives. According to a randomized, double-blind, controlled, cross-over design, 19 patients were assigned to consume black tea (129 mg flavonoids or placebo twice a day for eight days (13 day wash-out period. Digital volume pulse and BP were measured before and 1, 2, 3 and 4 h after tea consumption. Measurements were performed in a fasted state and after a fat load. Compared to placebo, reflection index and stiffness index decreased after tea consumption (p < 0.0001. Fat challenge increased wave reflection, which was counteracted by tea consumption (p < 0.0001. Black tea decreased systolic and diastolic BP (−3.2 mmHg, p < 0.005 and −2.6 mmHg, p < 0.0001; respectively and prevented BP increase after a fat load (p < 0.0001. Black tea consumption lowers wave reflections and BP in the fasting state, and during the challenging haemodynamic conditions after a fat load in hypertensives. Considering lipemia-induced impairment of arterial function may occur frequently during the day, our findings suggest regular consumption of black tea may be relevant for cardiovascular protection.

  4. Neural activity associated with self-reflection.

    Science.gov (United States)

    Herwig, Uwe; Kaffenberger, Tina; Schell, Caroline; Jäncke, Lutz; Brühl, Annette B

    2012-05-24

    Self-referential cognitions are important for self-monitoring and self-regulation. Previous studies have addressed the neural correlates of self-referential processes in response to or related to external stimuli. We here investigated brain activity associated with a short, exclusively mental process of self-reflection in the absence of external stimuli or behavioural requirements. Healthy subjects reflected either on themselves, a personally known or an unknown person during functional magnetic resonance imaging (fMRI). The reflection period was initialized by a cue and followed by photographs of the respective persons (perception of pictures of oneself or the other person). Self-reflection, compared with reflecting on the other persons and to a major part also compared with perceiving photographs of one-self, was associated with more prominent dorsomedial and lateral prefrontal, insular, anterior and posterior cingulate activations. Whereas some of these areas showed activity in the "other"-conditions as well, self-selective characteristics were revealed in right dorsolateral prefrontal and posterior cingulate cortex for self-reflection; in anterior cingulate cortex for self-perception and in the left inferior parietal lobe for self-reflection and -perception. Altogether, cingulate, medial and lateral prefrontal, insular and inferior parietal regions show relevance for self-related cognitions, with in part self-specificity in terms of comparison with the known-, unknown- and perception-conditions. Notably, the results are obtained here without behavioural response supporting the reliability of this methodological approach of applying a solely mental intervention. We suggest considering the reported structures when investigating psychopathologically affected self-related processing.

  5. Gene expression changes reflect clinical response in a placebo-controlled randomized trial of abatacept in patients with diffuse cutaneous systemic sclerosis.

    Science.gov (United States)

    Chakravarty, Eliza F; Martyanov, Viktor; Fiorentino, David; Wood, Tammara A; Haddon, David James; Jarrell, Justin Ansel; Utz, Paul J; Genovese, Mark C; Whitfield, Michael L; Chung, Lorinda

    2015-06-13

    Systemic sclerosis is an autoimmune disease characterized by inflammation and fibrosis of the skin and internal organs. We sought to assess the clinical and molecular effects associated with response to intravenous abatacept in patients with diffuse cutaneous systemic. Adult diffuse cutaneous systemic sclerosis patients were randomized in a 2:1 double-blinded fashion to receive abatacept or placebo over 24 weeks. Primary outcomes were safety and the change in modified Rodnan Skin Score (mRSS) at week 24 compared with baseline. Improvers were defined as patients with a decrease in mRSS of ≥30% post-treatment compared to baseline. Skin biopsies were obtained for differential gene expression and pathway enrichment analyses and intrinsic gene expression subset assignment. Ten subjects were randomized to abatacept (n = 7) or placebo (n = 3). Disease duration from first non-Raynaud's symptom was significantly longer (8.8 ± 3.8 years vs. 2.4 ± 1.6 years, p = 0.004) and median mRSS was higher (30 vs. 22, p = 0.05) in the placebo compared to abatacept group. Adverse events were similar in the two groups. Five out of seven patients (71%) randomized to abatacept and one out of three patients (33%) randomized to placebo experienced ≥30% improvement in skin score. Subjects receiving abatacept showed a trend toward improvement in mRSS at week 24 (-8.6 ± 7.5, p = 0.0625) while those in the placebo group did not (-2.3 ± 15, p = 0.75). After adjusting for disease duration, mRSS significantly improved in the abatacept compared with the placebo group (abatacept vs. placebo mRSS decrease estimate -9.8, 95% confidence interval -16.7 to -3.0, p = 0.0114). In the abatacept group, the patients in the inflammatory intrinsic subset showed a trend toward greater improvement in skin score at 24 weeks compared with the patients in the normal-like intrinsic subset (-13.5 ± 3.1 vs. -4.5 ± 6.4, p = 0.067). Abatacept resulted in decreased CD28 co-stimulatory gene expression in improvers

  6. Reflection in Medical Diagnosis: A Literature Review

    OpenAIRE

    Mamede, Silvia; Schmidt, Henk G.

    2017-01-01

    Purpose: Reflection in medical diagnosis has been said to prevent errors by minimizing flaws in clinical reasoning. This claim, however, has been much disputed. While some studies show reflective reasoning to improve diagnostic performance, others find it to add nothing. This paper presents a narrative review of the literature on reflection in medical diagnosis aimed at addressing two questions: (1) how reflective reasoning has been conceived in this literature; and (2) what is the effect of ...

  7. CVD molybdenum films of high infrared reflectance

    Energy Technology Data Exchange (ETDEWEB)

    Carver, G. E.

    1979-01-01

    Molybdenum thin films of high infrared reflectance have been deposited by pyrolytic decomposition of molybdenum carbonyl (Mo(CO)/sub 6/), and by hydrogen reduction of molybdenum pentachloride (MoCl/sub 5/). Reflectance values within 0.7% of the reflectance of supersmooth bulk molybdenum have been attained by annealing films of lower reflectance in both reducing and non-reducing atmospheres. All depositions and anneals proceed at atmospheric pressure, facilitating a continuous, flow-through fabrication. These reflectors combine the high temperature stability of molybdenum thin films with the infrared reflectance of a material such as aluminum. Deposition from Mo(CO)/sub 6/ under oxidizing conditions, and subsequent anneal in a reducing atmosphere, results in films that combine high solar absorptance with low thermal emittance. If anti-reflected, black molybdenum films can serve as highly selective single layer photothermal converters. Structural, compositional, and crystallographic properties have been measured after both deposition and anneal.

  8. Direct Reflectance Measurements from Drones: Sensor Absolute Radiometric Calibration and System Tests for Forest Reflectance Characterization

    Science.gov (United States)

    Hakala, Teemu; Scott, Barry; Theocharous, Theo; Näsi, Roope; Suomalainen, Juha; Greenwell, Claire; Fox, Nigel

    2018-01-01

    Drone-based remote sensing has evolved rapidly in recent years. Miniaturized hyperspectral imaging sensors are becoming more common as they provide more abundant information of the object compared to traditional cameras. Reflectance is a physically defined object property and therefore often preferred output of the remote sensing data capture to be used in the further processes. Absolute calibration of the sensor provides a possibility for physical modelling of the imaging process and enables efficient procedures for reflectance correction. Our objective is to develop a method for direct reflectance measurements for drone-based remote sensing. It is based on an imaging spectrometer and irradiance spectrometer. This approach is highly attractive for many practical applications as it does not require in situ reflectance panels for converting the sensor radiance to ground reflectance factors. We performed SI-traceable spectral and radiance calibration of a tuneable Fabry-Pérot Interferometer -based (FPI) hyperspectral camera at the National Physical Laboratory NPL (Teddington, UK). The camera represents novel technology by collecting 2D format hyperspectral image cubes using time sequential spectral scanning principle. The radiance accuracy of different channels varied between ±4% when evaluated using independent test data, and linearity of the camera response was on average 0.9994. The spectral response calibration showed side peaks on several channels that were due to the multiple orders of interference of the FPI. The drone-based direct reflectance measurement system showed promising results with imagery collected over Wytham Forest (Oxford, UK). PMID:29751560

  9. Direct Reflectance Measurements from Drones: Sensor Absolute Radiometric Calibration and System Tests for Forest Reflectance Characterization.

    Science.gov (United States)

    Hakala, Teemu; Markelin, Lauri; Honkavaara, Eija; Scott, Barry; Theocharous, Theo; Nevalainen, Olli; Näsi, Roope; Suomalainen, Juha; Viljanen, Niko; Greenwell, Claire; Fox, Nigel

    2018-05-03

    Drone-based remote sensing has evolved rapidly in recent years. Miniaturized hyperspectral imaging sensors are becoming more common as they provide more abundant information of the object compared to traditional cameras. Reflectance is a physically defined object property and therefore often preferred output of the remote sensing data capture to be used in the further processes. Absolute calibration of the sensor provides a possibility for physical modelling of the imaging process and enables efficient procedures for reflectance correction. Our objective is to develop a method for direct reflectance measurements for drone-based remote sensing. It is based on an imaging spectrometer and irradiance spectrometer. This approach is highly attractive for many practical applications as it does not require in situ reflectance panels for converting the sensor radiance to ground reflectance factors. We performed SI-traceable spectral and radiance calibration of a tuneable Fabry-Pérot Interferometer -based (FPI) hyperspectral camera at the National Physical Laboratory NPL (Teddington, UK). The camera represents novel technology by collecting 2D format hyperspectral image cubes using time sequential spectral scanning principle. The radiance accuracy of different channels varied between ±4% when evaluated using independent test data, and linearity of the camera response was on average 0.9994. The spectral response calibration showed side peaks on several channels that were due to the multiple orders of interference of the FPI. The drone-based direct reflectance measurement system showed promising results with imagery collected over Wytham Forest (Oxford, UK).

  10. Randomizing Roaches: Exploring the "Bugs" of Randomization in Experimental Design

    Science.gov (United States)

    Wagler, Amy; Wagler, Ron

    2014-01-01

    Understanding the roles of random selection and random assignment in experimental design is a central learning objective in most introductory statistics courses. This article describes an activity, appropriate for a high school or introductory statistics course, designed to teach the concepts, values and pitfalls of random selection and assignment…

  11. Embedding reflection and learning into agile software development

    DEFF Research Database (Denmark)

    Babb, Jeffry; Hoda, Rashina; Nørbjerg, Jacob

    2014-01-01

    The theoretical underpinnings of agile methods emphasize regular reflection as a means to sustainable development pace and continuous learning, but in practice, high iteration pressure can diminish reflection opportunities. The Reflective Agile Learning Model (REALM) combines insights and results...... from studies of agile development practices in India, New Zealand, and the US with Schön’s theory of reflective practice to embed reflection in everyday agile practices....

  12. Random walk of passive tracers among randomly moving obstacles.

    Science.gov (United States)

    Gori, Matteo; Donato, Irene; Floriani, Elena; Nardecchia, Ilaria; Pettini, Marco

    2016-04-14

    This study is mainly motivated by the need of understanding how the diffusion behavior of a biomolecule (or even of a larger object) is affected by other moving macromolecules, organelles, and so on, inside a living cell, whence the possibility of understanding whether or not a randomly walking biomolecule is also subject to a long-range force field driving it to its target. By means of the Continuous Time Random Walk (CTRW) technique the topic of random walk in random environment is here considered in the case of a passively diffusing particle among randomly moving and interacting obstacles. The relevant physical quantity which is worked out is the diffusion coefficient of the passive tracer which is computed as a function of the average inter-obstacles distance. The results reported here suggest that if a biomolecule, let us call it a test molecule, moves towards its target in the presence of other independently interacting molecules, its motion can be considerably slowed down.

  13. Superconvergent sum rules for the normal reflectivity

    International Nuclear Information System (INIS)

    Furuya, K.; Zimerman, A.H.; Villani, A.

    1976-05-01

    Families of superconvergent relations for the normal reflectivity function are written. Sum rules connecting the difference of phases of the reflectivities of two materials are also considered. Finally superconvergence relations and sum rules for magneto-reflectivity in the Faraday and Voigt regimes are also studied

  14. Insight in Schizophrenia: Involvement of Self-Reflection Networks?

    Science.gov (United States)

    de Vos, Annerieke E.

    2013-01-01

    Background: Impaired insight is a common feature in psychosis and an important predictor of variables such as functional outcome, prognosis, and treatment adherence. A cognitive process that may underlie insight in psychosis is self-reflection, or the conscious evaluation of one’s traits and characteristics. The current study aims to investigate the neural correlates of self-reflective processing and its relationship with insight in schizophrenia. Methods: Forty-seven schizophrenia patients and 21 healthy controls performed a self-reflection task in a functional magnetic resonance imaging (fMRI) scanner. The tasks comprised a self-reflection, close other-reflection, and a semantic (baseline) condition. Insight scores were obtained with the Schedule of Assessment of Insight Expanded. In addition, cognitive insight scores were obtained (Beck Cognitive Insight Scale [BCIS]). Results: Schizophrenia patients demonstrated less activation in the posterior cingulate cortex in the self- and other-reflection conditions and less activation in the precuneus in the other-reflection condition compared with healthy controls. Better insight was associated with greater response in the inferior frontal gyrus, anterior insula, and inferior parietal lobule during self-reflection. In addition, better cognitive insight was associated with higher activation in ventromedial prefrontal cortex during self-reflection. Conclusion: In the current study, evidence for a relationship between self-reflection and insight in patients with schizophrenia was found in brain areas related to self-reflection, self/other distinction and source attribution. The findings support the rationale for a treatment that is currently under evaluation, which attempts to increase insight by enhancing self-reflection. PMID:23104865

  15. Bragg reflection program

    International Nuclear Information System (INIS)

    Lynn, J.W.

    This user's guide to the Bragg Reflection Program (BRP) is in the nature of an informal report. The general purpose of BRP is to scan a series of Bragg reflections automatically in order to obtain profiles and integrated intensities. The program is used in conjunction with the SUPERVISOR and READ packages, and the procedures for using it are similar to those for the Triple-Axis Control program. All the general features of the system, SUPERVISOR and READ packages as described in the Spectrometer Control Systems User's Guide are preserved. The presentation assumes that the reader is familiar with these. Sections are given on the READ package, execution and use, error messages, and output. A few sample problems are shown. (1 figure) (U.S.)

  16. Total internal reflection effect on gyrotropic interface

    Science.gov (United States)

    Glushchenko, Alexander G.; Glushchenko, Eugene P.; Zhukov, Sergey V.

    2018-02-01

    This article considers the physical features of total internal reflection at gyrotropic and isotropic interfaces for two cases: electrical gyrotropy (plasma) and magnetic gyrotropy (ferrite). It is shown that the plasma magnetization may lead to the formation of the total internal reflection effect, which does not occur in isotropic plasma. The threshold values of the magnetic field, which are necessary for the total internal reflection effect, are determined. The total internal reflection effect on a ferrite-dielectric interface for waves emanating from different angles is observed in various frequency ranges and magnetization fields. The study points out the possibility of changing the total internal reflection angle value in large limits due to a change in the external magnetic field magnitude. The calculation results of the total internal reflection angle dependence on the external magnetic field magnitude are presented. The formulas are elaborated for calculating the total internal reflection angles of different interfaces for gyrotropic and isotropic media. The generalized formulas are defined for calculating the Doppler effect in the gyrotropic media. The study demonstrates how the velocity of the media interface affects the limiting angle of total internal refection.

  17. Library search with regular reflectance IR spectra

    International Nuclear Information System (INIS)

    Staat, H.; Korte, E.H.; Lampen, P.

    1989-01-01

    Characterisation in situ for coatings and other surface layers is generally favourable, but a prerequisite for precious items such as art objects. In infrared spectroscopy only reflection techniques are applicable here. However for attenuated total reflection (ATR) it is difficult to obtain the necessary optical contact of the crystal with the sample, when the latter is not perfectly plane or flexible. The measurement of diffuse reflectance demands a scattering sample and usually the reflectance is very poor. Therefore in most cases one is left with regular reflectance. Such spectra consist of dispersion-like feature instead of bands impeding their interpretation in the way the analyst is used to. Furthermore for computer search in common spectral libraries compiled from transmittance or absorbance spectra a transformation of the reflectance spectra is needed. The correct conversion is based on the Kramers-Kronig transformation. This somewhat time - consuming procedure can be speeded up by using appropriate approximations. A coarser conversion may be obtained from the first derivative of the reflectance spectrum which resembles the second derivative of a transmittance spectrum. The resulting distorted spectra can still be used successfully for the search in peak table libraries. Experiences with both transformations are presented. (author)

  18. Assessing Reflection: Understanding Skill Development through Reflective Learning Journals

    Science.gov (United States)

    Cathro, Virginia; O'Kane, Paula; Gilbertson, Deb

    2017-01-01

    Purpose: The purpose of this paper is to suggest ways in which business educators can interact successfully with reflective learning journals (RLJs). Specifically, the research was interested in how students used RLJs and how educators assessed these RLJs. Design/methodology/approach: In total, 31 RLJs, submitted as part of an international…

  19. The Effects of Reflective Training on the Disposition of Critical Thinking for Nursing Students in China: A Controlled Trial.

    Science.gov (United States)

    Zhang, Caihong; Fan, Huiying; Xia, Jieqiong; Guo, Honghua; Jiang, Xinjun; Yan, Yane

    2017-09-01

    The aim of this study was to evaluate the effects of reflective trainings for nursing students on their critical thinking disposition. A total of 157 senior undergraduate nursing students sampled from Hainan Medical University in China participated in this study in 2014. They were randomly divided into experimental and control groups. The experimental group students were provided the reflective training during their entire 12-month clinical internship, whereas students in the control group were requested to keep their reflective diaries but without a formal training. Before and after the intervention, nursing students' critical thinking disposition was rated using the Chinese version of Critical Thinking Disposition Inventory (CTDI-CV). Before the start of the intervention, the critical thinking disposition scores of the two groups had no significant differences. At the end of the intervention, it was found that the experimental students performed better in each subscale of CTDI-CV. These include the search for truth, open mind, analytical ability, systematic ability, critical thinking, self-confidence, curiosity, and cognitive maturity. By summing the scores of all categories, the results showed that the experimental group had a significantly higher total score than that of the control group (p ≤ .044). Evaluating the score difference in each function indicated that there was a range of improvements on the critical thinking disposition because of the reflective training intervention. Reflective training during the internship period improves nursing students' disposition of critical thinking and promotes their readiness for their clinical practices in the rapidly increasing demands of the healthcare field. Copyright © 2017. Published by Elsevier B.V.

  20. Flexible Bistable Cholesteric Reflective Displays

    Science.gov (United States)

    Yang, Deng-Ke

    2006-03-01

    Cholesteric liquid crystals (ChLCs) exhibit two stable states at zero field condition-the reflecting planar state and the nonreflecting focal conic state. ChLCs are an excellent candidate for inexpensive and rugged electronic books and papers. This paper will review the display cell structure,materials and drive schemes for flexible bistable cholesteric (Ch) reflective displays.

  1. Low reflectance high power RF load

    Science.gov (United States)

    Ives, R. Lawrence; Mizuhara, Yosuke M.

    2016-02-02

    A load for traveling microwave energy has an absorptive volume defined by cylindrical body enclosed by a first end cap and a second end cap. The first end cap has an aperture for the passage of an input waveguide with a rotating part that is coupled to a reflective mirror. The inner surfaces of the absorptive volume consist of a resistive material or are coated with a coating which absorbs a fraction of incident RF energy, and the remainder of the RF energy reflects. The angle of the reflector and end caps is selected such that reflected RF energy dissipates an increasing percentage of the remaining RF energy at each reflection, and the reflected RF energy which returns to the rotating mirror is directed to the back surface of the rotating reflector, and is not coupled to the input waveguide. Additionally, the reflector may have a surface which generates a more uniform power distribution function axially and laterally, to increase the power handling capability of the RF load. The input waveguide may be corrugated for HE11 mode input energy.

  2. LOD score exclusion analyses for candidate QTLs using random population samples.

    Science.gov (United States)

    Deng, Hong-Wen

    2003-11-01

    While extensive analyses have been conducted to test for, no formal analyses have been conducted to test against, the importance of candidate genes as putative QTLs using random population samples. Previously, we developed an LOD score exclusion mapping approach for candidate genes for complex diseases. Here, we extend this LOD score approach for exclusion analyses of candidate genes for quantitative traits. Under this approach, specific genetic effects (as reflected by heritability) and inheritance models at candidate QTLs can be analyzed and if an LOD score is < or = -2.0, the locus can be excluded from having a heritability larger than that specified. Simulations show that this approach has high power to exclude a candidate gene from having moderate genetic effects if it is not a QTL and is robust to population admixture. Our exclusion analysis complements association analysis for candidate genes as putative QTLs in random population samples. The approach is applied to test the importance of Vitamin D receptor (VDR) gene as a potential QTL underlying the variation of bone mass, an important determinant of osteoporosis.

  3. Thinking and writing at Masters level: a reflective passage.

    Science.gov (United States)

    Fowler, John

    This article identifies key characteristics of Masters level writing and the underpinning relationship of these characteristics to reflective thought. Classical models of reflective writing are reviewed and their focus on reflection as a progressive process is debated. A linear model of reflection is proposed and its application to reflective writing for Masters level assessments is examined. The classical authors tend to present reflection as a process in which the outcomes of reflection becomes deeper at advanced levels. While this is an appropriate application of the concept of reflection for the traditional academic essay, it might not always be so appropriate for other more applied aspects of thinking and writing particularly in the development of advanced nursing practice. A linear model of reflective writing which offers a more pragmatic perspective on reflection is developed.

  4. Improved estimation of heavy rainfall by weather radar after reflectivity correction and accounting for raindrop size distribution variability

    Science.gov (United States)

    Hazenberg, Pieter; Leijnse, Hidde; Uijlenhoet, Remko

    2015-04-01

    Between 25 and 27 August 2010 a long-duration mesoscale convective system was observed above the Netherlands, locally giving rise to rainfall accumulations exceeding 150 mm. Correctly measuring the amount of precipitation during such an extreme event is important, both from a hydrological and meteorological perspective. Unfortunately, the operational weather radar measurements were affected by multiple sources of error and only 30% of the precipitation observed by rain gauges was estimated. Such an underestimation of heavy rainfall, albeit generally less strong than in this extreme case, is typical for operational weather radar in The Netherlands. In general weather radar measurement errors can be subdivided into two groups: (1) errors affecting the volumetric reflectivity measurements (e.g. ground clutter, radar calibration, vertical profile of reflectivity) and (2) errors resulting from variations in the raindrop size distribution that in turn result in incorrect rainfall intensity and attenuation estimates from observed reflectivity measurements. A stepwise procedure to correct for the first group of errors leads to large improvements in the quality of the estimated precipitation, increasing the radar rainfall accumulations to about 65% of those observed by gauges. To correct for the second group of errors, a coherent method is presented linking the parameters of the radar reflectivity-rain rate (Z-R) and radar reflectivity-specific attenuation (Z-k) relationships to the normalized drop size distribution (DSD). Two different procedures were applied. First, normalized DSD parameters for the whole event and for each precipitation type separately (convective, stratiform and undefined) were obtained using local disdrometer observations. Second, 10,000 randomly generated plausible normalized drop size distributions were used for rainfall estimation, to evaluate whether this Monte Carlo method would improve the quality of weather radar rainfall products. Using the

  5. The role of emotion in design reflection

    NARCIS (Netherlands)

    Hammer, D.K.; Reymen, I.M.M.J.; Mcdonagh, Deana; Hekkert, Paul; Van Erp, Jeroen; Gyi, Diane

    2003-01-01

    Reflection on design processes performed by designers is called design reflection. In our view, this kind of reflection aims at answering essential questions like “Is my design answering the stakeholder concerns?”, “Am I solving the essential problems or am I wasting time on irrelevant aspects?”,

  6. Enabling Critical Reflection on Research Supervisory Practice

    Science.gov (United States)

    Pearson, Margot; Kayrooz, Carole

    2004-01-01

    This paper describes the development of an instrument--The Reflective Supervisor Questionnaire (RSQ). The RSQ maps the domain of research supervisory practice as a facilitative process involving educational tasks and activities. It is designed to assist research supervisors explore, by means of self-reflection and reflection on feedback from…

  7. Historical Text Comprehension Reflective Tutorial Dialogue System

    Science.gov (United States)

    Grigoriadou, Maria; Tsaganou, Grammatiki; Cavoura, Theodora

    2005-01-01

    The Reflective Tutorial Dialogue System (ReTuDiS) is a system for learner modelling historical text comprehension through reflective dialogue. The system infers learners' cognitive profiles and constructs their learner models. Based on the learner model the system plans the appropriate--personalized for learners--reflective tutorial dialogue in…

  8. Spatial Analysis of “Crazy Quilts”, a Class of Potentially Random Aesthetic Artefacts

    Science.gov (United States)

    Westphal-Fitch, Gesche; Fitch, W. Tecumseh

    2013-01-01

    Human artefacts in general are highly structured and often display ordering principles such as translational, reflectional or rotational symmetry. In contrast, human artefacts that are intended to appear random and non symmetrical are very rare. Furthermore, many studies show that humans find it extremely difficult to recognize or reproduce truly random patterns or sequences. Here, we attempt to model two-dimensional decorative spatial patterns produced by humans that show no obvious order. “Crazy quilts” represent a historically important style of quilt making that became popular in the 1870s, and lasted about 50 years. Crazy quilts are unusual because unlike most human artefacts, they are specifically intended to appear haphazard and unstructured. We evaluate the degree to which this intention was achieved by using statistical techniques of spatial point pattern analysis to compare crazy quilts with regular quilts from the same region and era and to evaluate the fit of various random distributions to these two quilt classes. We found that the two quilt categories exhibit fundamentally different spatial characteristics: The patch areas of crazy quilts derive from a continuous random distribution, while area distributions of regular quilts consist of Gaussian mixtures. These Gaussian mixtures derive from regular pattern motifs that are repeated and we suggest that such a mixture is a distinctive signature of human-made visual patterns. In contrast, the distribution found in crazy quilts is shared with many other naturally occurring spatial patterns. Centroids of patches in the two quilt classes are spaced differently and in general, crazy quilts but not regular quilts are well-fitted by a random Strauss process. These results indicate that, within the constraints of the quilt format, Victorian quilters indeed achieved their goal of generating random structures. PMID:24066095

  9. On a randomly imperfect spherical cap pressurized by a random ...

    African Journals Online (AJOL)

    In this paper, we investigate a dynamical system in a random setting of dual randomness in space and time variables in which both the imperfection of the structure and the load function are considered random , each with a statistical zero-mean .The auto- covariance of the load is correlated as an exponentially decaying ...

  10. Reflective self-awareness and conscious states

    DEFF Research Database (Denmark)

    Kjaer, Troels W; Nowak, Markus; Lou, Hans C

    2002-01-01

    A recent meta-analysis has shown precuneus, angular gyri, anterior cingulate gyri, and adjacent structures to be highly metabolically active in support of resting consciousness. We hypothesize that these regions constitute a functional network of reflective self-awareness thought to be a core...... function of consciousness. Seven normal volunteers were asked to think intensely on how they would describe the personality traits and physical appearance of themselves and a neutral reference person known to all the subjects (the Danish Queen). During each of the four conditions cerebral blood flow...... during reflective self-awareness. The commonality between the neural networks of the resting conscious state and self-awareness reflects the phenomenological concept of a fundamental contribution of reflective self-awareness to the contents and coherence of the conscious state....

  11. Incoherent and coherent backscattering of light by a layer of densely packed random medium

    Energy Technology Data Exchange (ETDEWEB)

    Tishkovets, Victor P. [Institute of Radio Astronomy of NASU, 4 Chervonopraporna Street, Kharkiv 61002 (Ukraine)], E-mail: tishkovets@ira.kharkov.ua

    2007-12-15

    The problem of light scattering by a layer of densely packed discrete random medium is considered. The theory of light scattering by systems of nonspherical particles is applied to derive equations corresponding to incoherent (diffuse) and interference parts of radiation reflected from the medium. A solution of the system of linear equations describing light scattering by a system of particles is represented by iteration. It is shown that the symmetry properties of the T-matrices and of the translation coefficients for the vector Helmholtz harmonics lead to the reciprocity relation for an arbitrary iteration. This relation is applied to consider the backscattering enhancement phenomenon. Equations expressing the incoherent and interference parts of reflected light from statistically homogeneous and isotropic plane-parallel layer of medium are given. In the exact backscattering direction the relation between incoherent and interference parts is identical to that of sparse media.

  12. Towards a Theory of the Ecology of Reflection: Reflective Practice for Experiential Learning in Higher Education

    Science.gov (United States)

    Harvey, Marina; Coulson, Debra; McMaugh, Anne

    2016-01-01

    Reflective practice is widely adopted across the field of experience-based learning subjects in higher education, including practicums, work-integrated learning, internships, service learning and community participation. This adoption of reflective practice implies that it supports student learning through experience. When reviewing the evidence…

  13. Interdisciplinarity and self-reflection in civic education

    DEFF Research Database (Denmark)

    Christensen, Torben Spanget

    2013-01-01

    are complex and can only be understood interdisciplinary. Therefore the ability to reflect problems interdisciplinary is crucial to the global citizen. The second argument is that the ability of self-reflection is necessary for citizens in their efforts to understand, maintain and develop their own...... on interdisciplinarity and self-reflection-as-citizen as key tools for analyzing societal problems and to act democratically on them. And it is suggested that dealing with interdisciplinarity requires use of second order concepts and that self-reflection as citizens requires third order concepts...

  14. Methodological Reflections: Inter- ethnic Research

    DEFF Research Database (Denmark)

    Singla, Rashmi

    2010-01-01

    with both youth and the parental generation with ethnic minority background in Denmark. These reflections include implications and challenges related to researcher’s national, ethnic background and educational, professional position in encounter with   diverse ‘researched persons’ such as youth......This article reflects on the methodological and epistemological aspects of the ethical issues involved in encounters between researcher and research participants with ethnic minority background in contexts with diversity. Specific challenges involved in longitudinal research (10 - 15 years......) are also considered. The issues related to the social relevance of the research deriving from psycho political validity implying consideration of power dynamics in the personal, relational and collective domains are included. The primary basis for these reflections is a follow-up study concerning young...

  15. A Method of Retrieving BRDF from Surface-Reflected Radiance Using Decoupling of Atmospheric Radiative Transfer and Surface Reflection

    Directory of Open Access Journals (Sweden)

    Alexander Radkevich

    2018-04-01

    Full Text Available Bi-directional reflection distribution function (BRDF defines anisotropy of the surface reflection. It is required to specify the boundary condition for radiative transfer (RT modeling used in aerosol retrievals, cloud retrievals, atmospheric modeling, and other applications. Ground based measurements of reflected radiance draw increasing attention as a source of information about anisotropy of surface reflection. Derivation of BRDF from surface radiance requires atmospheric correction. This study develops a new method of retrieving BRDF on its whole domain, making it immediately suitable for further atmospheric RT modeling applications. The method is based on the integral equation relating surface-reflected radiance, BRDF, and solutions of two auxiliary atmosphere-only RT problems. The method requires kernel-based BRDF. The weights of the kernels are obtained with a quickly converging iterative procedure. RT modeling has to be done only one time before the start of iterative process.

  16. Improving Teaching through Collaborative Reflective Teaching Cycles

    Science.gov (United States)

    Murray, Eileen

    2015-01-01

    Reflection and collaboration are two activities teachers can use to change and improve their practice. However, finding the time and space to do so can be challenging. The collaborative reflective teaching cycle is a structured activity teachers can use to engage in reflection and collaboration. This article describes how a seventh grade teaching…

  17. Unraveling spurious properties of interaction networks with tailored random networks.

    Directory of Open Access Journals (Sweden)

    Stephan Bialonski

    Full Text Available We investigate interaction networks that we derive from multivariate time series with methods frequently employed in diverse scientific fields such as biology, quantitative finance, physics, earth and climate sciences, and the neurosciences. Mimicking experimental situations, we generate time series with finite length and varying frequency content but from independent stochastic processes. Using the correlation coefficient and the maximum cross-correlation, we estimate interdependencies between these time series. With clustering coefficient and average shortest path length, we observe unweighted interaction networks, derived via thresholding the values of interdependence, to possess non-trivial topologies as compared to Erdös-Rényi networks, which would indicate small-world characteristics. These topologies reflect the mostly unavoidable finiteness of the data, which limits the reliability of typically used estimators of signal interdependence. We propose random networks that are tailored to the way interaction networks are derived from empirical data. Through an exemplary investigation of multichannel electroencephalographic recordings of epileptic seizures--known for their complex spatial and temporal dynamics--we show that such random networks help to distinguish network properties of interdependence structures related to seizure dynamics from those spuriously induced by the applied methods of analysis.

  18. The differential equation of an arbitrary reflecting surface

    Science.gov (United States)

    Melka, Richard F.; Berrettini, Vincent D.; Yousif, Hashim A.

    2018-05-01

    A differential equation describing the reflection of a light ray incident upon an arbitrary reflecting surface is obtained using the law of reflection. The derived equation is written in terms of a parameter and the value of this parameter determines the nature of the reflecting surface. Under various parametric constraints, the solution of the differential equation leads to the various conic surfaces but is not generally solvable. In addition, the dynamics of the light reflections from the conic surfaces are executed in the Mathematica software. Our derivation is the converse of the traditional approach and our analysis assumes a relation between the object distance and the image distance. This leads to the differential equation of the reflecting surface.

  19. Reflections

    Directory of Open Access Journals (Sweden)

    Joanne Embree

    2001-01-01

    Full Text Available Ideally, editorials are written one to two months before publication in the Journal. It was my turn to write this one. I had planned to write the first draft the evening after my clinic on Tuesday, September 11. It didn't get done that night or during the next week. Somehow, the topic that I had originally chosen just didn't seem that important anymore as I, along my friends and colleagues, reflected on the changes that the events of that day were likely to have on our lives.

  20. Reflective Journals: A Review of the Literature

    Science.gov (United States)

    Lindroth, James T.

    2015-01-01

    The use of reflective journals has been identified as an effective tool to promote reflection in preservice teachers. This review of literature provides the reader with an understanding of the various ways journals are used and assessed in teacher education programs. The findings of this review outline the use of reflective journals on topics such…

  1. Self-reflection Orients Visual Attention Downward.

    Science.gov (United States)

    Liu, Yi; Tong, Yu; Li, Hong

    2017-01-01

    Previous research has demonstrated abstract concepts associated with spatial location (e.g., God in the Heavens) could direct visual attention upward or downward, because thinking about the abstract concepts activates the corresponding vertical perceptual symbols. For self-concept, there are similar metaphors (e.g., "I am above others"). However, whether thinking about the self can induce visual attention orientation is still unknown. Therefore, the current study tested whether self-reflection can direct visual attention. Individuals often display the tendency of self-enhancement in social comparison, which reminds the individual of the higher position one possesses relative to others within the social environment. As the individual is the agent of the attention orientation, and high status tends to make an individual look down upon others to obtain a sense of pride, it was hypothesized that thinking about the self would lead to a downward attention orientation. Using reflection of personality traits and a target discrimination task, Study 1 found that, after self-reflection, visual attention was directed downward. Similar effects were also found after friend-reflection, with the level of downward attention being correlated with the likability rating scores of the friend. Thus, in Study 2, a disliked other was used as a control and the positive self-view was measured with above-average judgment task. We found downward attention orientation after self-reflection, but not after reflection upon the disliked other. Moreover, the attentional bias after self-reflection was correlated with above-average self-view. The current findings provide the first evidence that thinking about the self could direct visual-spatial attention downward, and suggest that this effect is probably derived from a positive self-view within the social context.

  2. Random matrix ensembles with random interactions: Results for ...

    Indian Academy of Sciences (India)

    ... Public Lectures · Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Pramana – Journal of Physics; Volume 73; Issue 3. Random matrix ensembles with random interactions: Results for EGUE(2)-(4). Manan Vyas Manan Vyas. Volume 73 Issue 3 September 2009 pp 521-531 ...

  3. Reflective masks for extreme ultraviolet lithography

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Khanh Bao [Univ. of California, Berkeley, CA (United States)

    1994-05-01

    Extreme ultraviolet lithographic masks are made by patterning multilayer reflective coatings with high normal incidence reflectivity. Masks can be patterned by depositing a patterned absorber layer above the coating or by etching the pattern directly into the coating itself. Electromagnetic simulations showed that absorber-overlayer masks have superior imaging characteristics over etched masks (less sensitive to incident angles and pattern profiles). In an EUVL absorber overlayer mask, defects can occur in the mask substrate, reflective coating, and absorber pattern. Electromagnetic simulations showed that substrate defects cause the most severe image degradation. A printability study of substrate defects for absorber overlayer masks showed that printability of 25 nm high substrate defects are comparable to defects in optical lithography. Simulations also indicated that the manner in which the defects are covered by multilayer reflective coatings can affect printability. Coverage profiles that result in large lateral spreading of defect geometries amplify the printability of the defects by increasing their effective sizes. Coverage profiles of Mo/Si coatings deposited above defects were studied by atomic force microscopy and TEM. Results showed that lateral spread of defect geometry is proportional to height. Undercut at defect also increases the lateral spread. Reductions in defect heights were observed for 0.15 μm wide defect lines. A long-term study of Mo/Si coating reflectivity revealed that Mo/Si coatings with Mo as the top layer suffer significant reductions in reflectivity over time due to oxidation.

  4. The Relevance of Reflection: An Empirical Examination of the Role of Reflection in Ethic of Caring, Leadership, and Psychological Well-Being

    Science.gov (United States)

    Park, Julie J.; Millora, Melissa L.

    2012-01-01

    This article is an empirical examination of reflection for first-year and third-year students using data from the College Students' Beliefs and Values survey. Frequency of self-reflection increased between the first and third years of college. Two self-reported measures of reflection, engaging in self-reflection and having classes that…

  5. Reflecting on Hell in Anticipation of Armageddon: The Impact of Reflection and Adaptation on the Education of the US Army Officer Corps

    Science.gov (United States)

    2016-05-10

    Reflecting on Hell in Anticipation of Armageddon: The Impact of Reflection and...Hell in Anticipation of Armageddon: The Impact of Reflection and Adaptation on the Education of the US Army Officer Corps Sb. GRANT NUMBER Sc...Monograph Title: Reflecting on Hell in Anticipation of Armageddon: The Impact of Reflection and Adaptation on the Education of the US Army Officer Corps

  6. Random Intercept and Random Slope 2-Level Multilevel Models

    Directory of Open Access Journals (Sweden)

    Rehan Ahmad Khan

    2012-11-01

    Full Text Available Random intercept model and random intercept & random slope model carrying two-levels of hierarchy in the population are presented and compared with the traditional regression approach. The impact of students’ satisfaction on their grade point average (GPA was explored with and without controlling teachers influence. The variation at level-1 can be controlled by introducing the higher levels of hierarchy in the model. The fanny movement of the fitted lines proves variation of student grades around teachers.

  7. Coupled continuous time-random walks in quenched random environment

    Science.gov (United States)

    Magdziarz, M.; Szczotka, W.

    2018-02-01

    We introduce a coupled continuous-time random walk with coupling which is characteristic for Lévy walks. Additionally we assume that the walker moves in a quenched random environment, i.e. the site disorder at each lattice point is fixed in time. We analyze the scaling limit of such a random walk. We show that for large times the behaviour of the analyzed process is exactly the same as in the case of uncoupled quenched trap model for Lévy flights.

  8. Existing reflection seismic data re-processing

    International Nuclear Information System (INIS)

    Higashinaka, Motonori; Sano, Yukiko; Kozawa, Takeshi

    2005-08-01

    This document is to report the results of existing seismic data re-processing around Horonobe town, Hokkaido, Japan, which is a part of the Horonobe Underground Research Project. The main purpose of this re-processing is to recognize the subsurface structure of Omagari Fault and fold system around Omagari Fault. The seismic lines for re-processing are TYHR-A3 line and SHRB-2 line, which JAPEX surveyed in 1975. Applying weathering static correction using refraction analysis and noise suppression procedure, we have much enhanced seismic profile. Following information was obtained from seismic re-processing results. TYHR-A3 line: There are strong reflections, dipping to the west. These reflections are corresponding western limb of anticline to the west side of Omagari Fault. SHRB-2 line: There are strong reflections, dipping to the west, at CDP 60-140, while there are reflections, dipping to the east, to the east side of CDP 140. These reflections correspond to the western limb and the eastern limb of the anticline, which is parallel to Omagari FAULT. This seismic re-processing provides some useful information to know the geological structure around Omagari Fault. (author)

  9. Requirements for reflection in the critical care environment

    Directory of Open Access Journals (Sweden)

    Celia J. Filmalter

    2015-03-01

    Full Text Available Background: Reflection is recognised as an important method for practice development. The importance of reflection is well documented in the literature, but the requirements for reflection remain unclear. Objectives: To explore and describe the requirements for reflection in the critical care environment as viewed by educators of qualified critical care nurses. Method: A focus group interview was conducted to explore and describe the views of educators of qualified critical care nurses regarding requirements for reflection in the critical care environment. Results: The themes that emerged from the focus group were buy-in from stakeholders –management, facilitators and critical care nurses, and the need to create an environment where reflection can occur. Conclusion: Critical care nurses should be allowed time to reflect on their practice and be supported by peers as well as a facilitator in a non-intimidating way to promote emancipatorypractice development.

  10. Salinity and spectral reflectance of soils

    Science.gov (United States)

    Szilagyi, A.; Baumgardner, M. F.

    1991-01-01

    The basic spectral response related to the salt content of soils in the visible and reflective IR wavelengths is analyzed in order to explore remote sensing applications for monitoring processes of the earth system. The bidirectional reflectance factor (BRF) was determined at 10 nm of increments over the 520-2320-nm spectral range. The effect of salts on reflectance was analyzed on the basis of 162 spectral measurements. MSS and TM bands were simulated within the measured spectral region. A strong relationship was found in variations of reflectance and soil characteristics pertaining to salinization and desalinization. Although the individual MSS bands had high R-squared values and 75-79 percent of soil/treatment combinations were separable, there was a large number of soil/treatment combinations not distinguished by any of the four highly correlated MSS bands under consideration.

  11. Audible reflection density for different late reflection criteria in rooms

    DEFF Research Database (Denmark)

    Krueger, Donata; Jeong, Cheol-Ho; Brunskog, Jonas

    2012-01-01

    For reasonably accurate but practical auralizations, some simplifications and approximations are needed. The main issue in the present investigation is that the reflection density of a room impulse response, in theory, increases so fast as a quadratic function of the elapsed time, even assuming...

  12. Textural properties of chars as determined by petrographic analysis: comparison between air-blown, oxygen-blown and oxygen-enriched gasification

    CSIR Research Space (South Africa)

    Oboirien, BO

    2012-11-01

    Full Text Available In this study, the textural properties of chars generated from a vitrinite, high ash coal in a fluidised bed gasifier under air-blown, oxygen-blown and oxygen-enriched conditions were determined by detailed petrographic analysis. The char samples...

  13. A theoretical and numerical study of polarimetric scattering and emission from random rough surfaces with anisotropic directional spectrum

    Science.gov (United States)

    Yueh, S. H.; Kwok, R.

    1993-01-01

    In this paper, theoretical and numerical results of the polarimetric scattering and emission from random rough surfaces with anisotropic directional spectrum are presented for the remote sensing of ocean and soil surfaces. The polarimetric scattered field for rough dielectric surfaces is derived to the second order by the small perturbation method (SPM). It is found that the second-order scattered field is coherent in nature, and its coefficients for different polarizations present the lowest-order corrections to the Fresnel reflection coefficients of the surfaces. In addition, the cross-polarized (HV and VH) components of the coherent fields are reciprocal and not zero for surfaces with anisotropic directional spectrum when the azimuth angle of the incident direction is not aligned with the symmetry directions of surfaces. In order to verify the energy conservation condition of the theoretical results, which is important if the theory is to be applied to the passive polarimetry of rough surfaces, a Monte Carlo simulation is performed to numerically calculate the polarimetric reflectivities of one-dimensional random rough surfaces which are generated with a prescribed power-law spectrum in the spectral domain and transformed to the spatial domain by the FFT. The surfaces simulated by this approach are periodic with the period corresponding to the low-wavenumber cutoff. To calculate the scattering from periodic dielectric surfaces, the authors present a new numerical technique which applies the Floquet theorem to reduce the problem to one period and does not require the evaluation of one-dimensional periodic Green's function used in the conventional method of moment formulation. Once the scattering coefficients are obtained, the polarimetric Stokes vectors for the emission from the random surfaces are then calculated according to the Kirchhoff's law and are illustrated as functions of relative azimuth observation and row directions. The second-order SPM is also

  14. Moving from technical to critical reflection in journalling: an investigation of students' ability to incorporate three levels of reflective writing.

    Science.gov (United States)

    Usher, K; Tollefson, J; Francis, D

    2001-01-01

    This paper outlines a research project aimed at changing the levels of reflection of preregistration nursing students in a tertiary institution. Whilst reflection is widely espoused now in nursing, few studies have been found that identify whether the level of reflective writing can be identified or developed by students. Anecdotal and research evidence (Powell 1989; van Manen 1977) however indicates that most student reflective writing occurs at the technical level. A descriptive exploratory study using both qualitative and quantitative techniques was undertaken to apply van Manen's (1977) levels in a structured way in an attempt to facilitate the student's understanding and use of the levels in their reflective writing. The findings of the study indicate that student self evaluation and identification of the levels in their own writing can lead to change in the levels of critical reflective writing achieved by undergraduate students.

  15. Personal Professional Reflection as Interdisciplinary Problem

    Directory of Open Access Journals (Sweden)

    Rezvan Oksana

    2013-08-01

    Full Text Available Consideration of professional reflection as interdisciplinary problem is the necessary condition of quality analysis for personal professional becoming. Personal becoming in a profession is related to forming the necessary professional skills of a person, behaviour stereotypes which is the area of pedagogics. Reflection processes are inalienable part of self-knowledge of a person which result must lead to his self-perfection (including professional one and studying within the psychology increasingly. Thus the aim of the article is to ground the determination of professional reflection as an interdisciplinary problem in pedagogics and psychology.

  16. Gaze-Contingent Music Reward Therapy for Social Anxiety Disorder: A Randomized Controlled Trial.

    Science.gov (United States)

    Lazarov, Amit; Pine, Daniel S; Bar-Haim, Yair

    2017-07-01

    Patients with social anxiety disorder exhibit increased attentional dwelling on social threats, providing a viable target for therapeutics. This randomized controlled trial examined the efficacy of a novel gaze-contingent music reward therapy for social anxiety disorder designed to reduce attention dwelling on threats. Forty patients with social anxiety disorder were randomly assigned to eight sessions of either gaze-contingent music reward therapy, designed to divert patients' gaze toward neutral stimuli rather than threat stimuli, or to a control condition. Clinician and self-report measures of social anxiety were acquired pretreatment, posttreatment, and at 3-month follow-up. Dwell time on socially threatening faces was assessed during the training sessions and at pre- and posttreatment. Gaze-contingent music reward therapy yielded greater reductions of symptoms of social anxiety disorder than the control condition on both clinician-rated and self-reported measures. Therapeutic effects were maintained at follow-up. Gaze-contingent music reward therapy, but not the control condition, also reduced dwell time on threat, which partially mediated clinical effects. Finally, gaze-contingent music reward therapy, but not the control condition, also altered dwell time on socially threatening faces not used in training, reflecting near-transfer training generalization. This is the first randomized controlled trial to examine a gaze-contingent intervention in social anxiety disorder. The results demonstrate target engagement and clinical effects. This study sets the stage for larger randomized controlled trials and testing in other emotional disorders.

  17. Seismic reflection data imaging and interpretation from Braniewo2014 experiment using additional wide-angle refraction and reflection and well-logs data

    Science.gov (United States)

    Trzeciak, Maciej; Majdański, Mariusz; Białas, Sebastian; Gaczyński, Edward; Maksym, Andrzej

    2015-04-01

    Braniewo2014 reflection and refraction experiment was realized in cooperation between Polish Oil and Gas Company (PGNiG) and the Institute of Geophysics (IGF), Polish Academy of Sciences, near the locality of Braniewo in northern Poland. PGNiG realized a 20-km-long reflection profile, using vibroseis and dynamite shooting; the aim of the reflection survey was to characterise Silurian shale gas reservoir. IGF deployed 59 seismic stations along this profile and registered additional full-spread wide-angle refraction and reflection data, with offsets up to 12 km; maximum offsets from the seismic reflection survey was 3 km. To improve the velocity information two velocity logs from near deep boreholes were used. The main goal of the joint reflection-refraction interpretation was to find relations between velocity field from reflection velocity analysis and refraction tomography, and to build a velocity model which would be consistent for both, reflection and refraction, datasets. In this paper we present imaging results and velocity models from Braniewo2014 experiment and the methodology we used.

  18. Reflect: a practical approach to web semantics

    DEFF Research Database (Denmark)

    O'Donoghue, S.I.; Horn, Heiko; Pafilisa, E.

    2010-01-01

    To date, adding semantic capabilities to web content usually requires considerable server-side re-engineering, thus only a tiny fraction of all web content currently has semantic annotations. Recently, we announced Reflect (http://reflect.ws), a free service that takes a more practical approach......: Reflect uses augmented browsing to allow end-users to add systematic semantic annotations to any web-page in real-time, typically within seconds. In this paper we describe the tagging process in detail and show how further entity types can be added to Reflect; we also describe how publishers and content...... web technologies....

  19. Generalizing Evidence From Randomized Clinical Trials to Target Populations

    Science.gov (United States)

    Cole, Stephen R.; Stuart, Elizabeth A.

    2010-01-01

    Properly planned and conducted randomized clinical trials remain susceptible to a lack of external validity. The authors illustrate a model-based method to standardize observed trial results to a specified target population using a seminal human immunodeficiency virus (HIV) treatment trial, and they provide Monte Carlo simulation evidence supporting the method. The example trial enrolled 1,156 HIV-infected adult men and women in the United States in 1996, randomly assigned 577 to a highly active antiretroviral therapy and 579 to a largely ineffective combination therapy, and followed participants for 52 weeks. The target population was US people infected with HIV in 2006, as estimated by the Centers for Disease Control and Prevention. Results from the trial apply, albeit muted by 12%, to the target population, under the assumption that the authors have measured and correctly modeled the determinants of selection that reflect heterogeneity in the treatment effect. In simulations with a heterogeneous treatment effect, a conventional intent-to-treat estimate was biased with poor confidence limit coverage, but the proposed estimate was largely unbiased with appropriate confidence limit coverage. The proposed method standardizes observed trial results to a specified target population and thereby provides information regarding the generalizability of trial results. PMID:20547574

  20. Spectral and geometrical variation of the bidirectional reflectance distribution function of diffuse reflectance standards.

    Science.gov (United States)

    Ferrero, Alejandro; Rabal, Ana María; Campos, Joaquín; Pons, Alicia; Hernanz, María Luisa

    2012-12-20

    A study on the variation of the spectral bidirectional reflectance distribution function (BRDF) of four diffuse reflectance standards (matte ceramic, BaSO(4), Spectralon, and white Russian opal glass) is accomplished through this work. Spectral BRDF measurements were carried out and, using principal components analysis, its spectral and geometrical variation respect to a reference geometry was assessed from the experimental data. Several descriptors were defined in order to compare the spectral BRDF variation of the four materials.

  1. Optical fringe-reflection deflectometry with bundle adjustment

    Science.gov (United States)

    Xiao, Yong-Liang; Li, Sikun; Zhang, Qican; Zhong, Jianxin; Su, Xianyu; You, Zhisheng

    2018-06-01

    Liquid crystal display (LCD) screens are located outside of a camera's field of view in fringe-reflection deflectometry. Therefore, fringes that are displayed on LCD screens are obtained through specular reflection by a fixed camera. Thus, the pose calibration between the camera and LCD screen is one of the main challenges in fringe-reflection deflectometry. A markerless planar mirror is used to reflect the LCD screen more than three times, and the fringes are mapped into the fixed camera. The geometrical calibration can be accomplished by estimating the pose between the camera and the virtual image of fringes. Considering the relation between their pose, the incidence and reflection rays can be unified in the camera frame, and a forward triangulation intersection can be operated in the camera frame to measure three-dimensional (3D) coordinates of the specular surface. In the final optimization, constraint-bundle adjustment is operated to refine simultaneously the camera intrinsic parameters, including distortion coefficients, estimated geometrical pose between the LCD screen and camera, and 3D coordinates of the specular surface, with the help of the absolute phase collinear constraint. Simulation and experiment results demonstrate that the pose calibration with planar mirror reflection is simple and feasible, and the constraint-bundle adjustment can enhance the 3D coordinate measurement accuracy in fringe-reflection deflectometry.

  2. Approximate reflection coefficients for a thin VTI layer

    KAUST Repository

    Hao, Qi

    2017-09-18

    We present an approximate method to derive simple expressions for the reflection coefficients of P- and SV-waves for a thin transversely isotropic layer with a vertical symmetry axis (VTI) embedded in a homogeneous VTI background. The layer thickness is assumed to be much smaller than the wavelengths of P- and SV-waves inside. The exact reflection and transmission coefficients are derived by the propagator matrix method. In the case of normal incidence, the exact reflection and transmission coefficients are expressed in terms of the impedances of vertically propagating P- and S-waves. For subcritical incidence, the approximate reflection coefficients are expressed in terms of the contrast in the VTI parameters between the layer and the background. Numerical examples are designed to analyze the reflection coefficients at normal and oblique incidence, and investigate the influence of transverse isotropy on the reflection coefficients. Despite giving numerical errors, the approximate formulae are sufficiently simple to qualitatively analyze the variation of the reflection coefficients with the angle of incidence.

  3. Self-Reflection and Academic Performance: Is There a Relationship?

    Science.gov (United States)

    Lew, Magdeleine D. N.; Schmidt, Henk G.

    2011-01-01

    The purposes of the present study were two-fold: first, to evaluate whether reflection journal writing was effective in promoting self-reflection and learning, and whether students become better at self-reflection if they engage continuously in reflection journal writing. To that end, the reflection journals of 690 first-year applied science…

  4. In Two Minds: How Reflections Influence Software Architecture Design Thinking : how reflections influence software design thinking

    NARCIS (Netherlands)

    Razavian, Maryam; Tang, Anthony; Capilla, Rafael; Lago, Patricia

    2016-01-01

    We theorize a two-mind model of design thinking. Mind 1 is about logical design reasoning, and Mind 2 is about the reflection on our reasoning and judgments. The problem solving ability of Mind 1 has often been emphasized in software engineering. The reflective Mind 2, however, has not received much

  5. Misuse of randomization

    DEFF Research Database (Denmark)

    Liu, Jianping; Kjaergard, Lise Lotte; Gluud, Christian

    2002-01-01

    The quality of randomization of Chinese randomized trials on herbal medicines for hepatitis B was assessed. Search strategy and inclusion criteria were based on the published protocol. One hundred and seventy-six randomized clinical trials (RCTs) involving 20,452 patients with chronic hepatitis B...... virus (HBV) infection were identified that tested Chinese medicinal herbs. They were published in 49 Chinese journals. Only 10% (18/176) of the studies reported the method by which they randomized patients. Only two reported allocation concealment and were considered as adequate. Twenty percent (30...

  6. Implementing reflection: insights from pre-registration mental health students.

    Science.gov (United States)

    Donovan, Moira O

    2007-08-01

    Reflection and reflective practice continues to be contentious issues in nursing. The focus of this article is the use of reflection by pre-registration mental health students. The broad aim of this preliminary study was to discover student mental health nurses' perceptions of reflection as a learning strategy during clinical placement. Using a constructivist grounded theory methodology [Charmaz, K., 2000. Grounded theory: Objectivist and Constructivist Methods. In: Denzin, N., Lincoln, Y. (Eds.), Handbook of Qualitative Research, second ed. Sage, Thousand Oaks, California], five students were interviewed individually in their clinical placements. Data analysis revealed three major categories: understanding the process of reflection, using reflection in clinical practice, and needing support and guidance. Findings indicated that students were primarily using reflection-on-action, but to varying extents. Overall, students felt that reflection facilitated their learning. Factors were discovered that both helped and hindered students' use of reflection. These included level of preparation to reflect, a limited culture of reflection and the level of support from preceptors, clinical staff, clinical placement co-ordinators, and lecturers. In conclusion, it appears that a collaborative approach between students, Health Service Providers and institutes of nursing is vital for the successful development and implementation of reflective learning strategies in clinical placement. Suggestions are made as to how a collaborative approach may be developed to enhance this process.

  7. Angular dependance of spectral reflection for different materials

    Science.gov (United States)

    Kiefer, Pascal M.

    2017-10-01

    Parameters like the sun angle as well as the measurement angle mostly are not taken into account when simulating because their influence on the reflectivity is weak. Therefore the impact of a changing measurement and illumination angle on the reflectivity is investigated. Furthermore the impact of humidity and chlorophyll in the scenery is studied by analyzing reflectance spectra of different vegetative background areas. It is shown that the measurement as well as the illumination angle has an important influence on the absolute reflection values which raises the importance of measurements of the bidirectional reflectance distribution function (BRDF).

  8. Characterizing the reflectivity of handheld display devices.

    Science.gov (United States)

    Liu, Peter; Badano, Aldo

    2014-08-01

    With increased use of handheld and tablet display devices for viewing medical images, methods for consistently measuring reflectivity of the devices are needed. In this note, the authors report on the characterization of diffuse reflections for handheld display devices including mobile phones and tablets using methods recommended by the American Association of Physicists in Medicine Task Group 18 (TG18). The authors modified the diffuse reflectance coefficient measurement method outlined in the TG18 report. The authors measured seven handheld display devices (two phones and five tablets) and three workstation displays. The device was attached to a black panel with Velcro. To study the effect of the back surface on the diffuse reflectance coefficient, the authors created Styrofoam masks with different size square openings and placed it in front of the device. Overall, for each display device, measurements of illuminance and reflected luminance on the display screen were taken. The authors measured with no mask, with masks of varying size, and with display-size masks, and calculated the corresponding diffuse reflectance coefficient. For all handhelds, the diffuse reflectance coefficient measured with no back panel were lower than measurements performed with a mask. The authors found an overall increase in reflectivity as the size of the mask decreases. For workstations displays, diffuse reflectance coefficients were higher when no back panel was used, and higher than with masks. In all cases, as luminance increased, illuminance increased, but not at the same rate. Since the size of handheld displays is smaller than that of workstation devices, the TG18 method suffers from a dependency on illumination condition. The authors show that the diffuse reflection coefficients can vary depending on the nature of the back surface of the illuminating box. The variability in the diffuse coefficient can be as large as 20% depending on the size of the mask. For all measurements

  9. Particle reflection and TFTR neutral beam diagnostics

    International Nuclear Information System (INIS)

    Kamperschroer, J.H.; Grisham, L.R.; Kugel, H.W.; O'Connor, T.E.; Newman, R.A.; Stevenson, T.N.; von Halle, A.; Williams, M.D.

    1992-04-01

    Determination of two critical neutral beam parameters, power and divergence, are affected by the reflection of a fraction of the incident energy from the surface of the measuring calorimeter. On the TFTR Neutral Beam Test Stand, greater than 30% of the incident power directed at the target chamber calorimeter was unaccounted for. Most of this loss is believed due to reflection from the surface of the flat calorimeter, which was struck at a near grazing incidence (12 degrees). Beamline calorimeters, of a ''V''-shape design, while retaining the beam power, also suffer from reflection effects. Reflection, in this latter case, artificially peaks the power toward the apex of the ''V'', complicating the fitting technique, and increasing the power density on axis by 10 to 20%; an effect of import to future beamline designers. Agreement is found between measured and expected divergence values, even with 24% of the incident energy reflected

  10. The Effects of Reflective Training on the Disposition of Critical Thinking for Nursing Students in China: A Controlled Trial

    Directory of Open Access Journals (Sweden)

    Caihong Zhang, Ph.D.

    2017-09-01

    Full Text Available Summary: Purpose: The aim of this study was to evaluate the effects of reflective trainings for nursing students on their critical thinking disposition. Methods: A total of 157 senior undergraduate nursing students sampled from Hainan Medical University in China participated in this study in 2014. They were randomly divided into experimental and control groups. The experimental group students were provided the reflective training during their entire 12-month clinical internship, whereas students in the control group were requested to keep their reflective diaries but without a formal training. Before and after the intervention, nursing students' critical thinking disposition was rated using the Chinese version of Critical Thinking Disposition Inventory (CTDI-CV. Results: Before the start of the intervention, the critical thinking disposition scores of the two groups had no significant differences. At the end of the intervention, it was found that the experimental students performed better in each subscale of CTDI-CV. These include the search for truth, open mind, analytical ability, systematic ability, critical thinking, self-confidence, curiosity, and cognitive maturity. By summing the scores of all categories, the results showed that the experimental group had a significantly higher total score than that of the control group (p ≤ .044. Evaluating the score difference in each function indicated that there was a range of improvements on the critical thinking disposition because of the reflective training intervention. Conclusion: Reflective training during the internship period improves nursing students' disposition of critical thinking and promotes their readiness for their clinical practices in the rapidly increasing demands of the healthcare field. Keywords: thinking, education, nursing, students, nursing

  11. Researching critical reflection in management education

    DEFF Research Database (Denmark)

    Elkjaer, Bente; Nickelsen, Niels Christian Mossfeldt

    2016-01-01

    Critical reflection for professionals involves the ability to learn directly from their practice experience, so that they can improve their own work in an ongoing and flexible way. By examining the fundamental bases of what they do systematically, critical reflection can also function as a form...... to deal with change and critical reflection provides one method for being able to incorporate changes in a way which allows individuals to preserve a sense of what is fundamentally important to them as professionals. Since many different professionals work together in most organisations, research...... of education, management, health and social work....

  12. BWIP-RANDOM-SAMPLING, Random Sample Generation for Nuclear Waste Disposal

    International Nuclear Information System (INIS)

    Sagar, B.

    1989-01-01

    1 - Description of program or function: Random samples for different distribution types are generated. Distribution types as required for performance assessment modeling of geologic nuclear waste disposal are provided. These are: - Uniform, - Log-uniform (base 10 or natural), - Normal, - Lognormal (base 10 or natural), - Exponential, - Bernoulli, - User defined continuous distribution. 2 - Method of solution: A linear congruential generator is used for uniform random numbers. A set of functions is used to transform the uniform distribution to the other distributions. Stratified, rather than random, sampling can be chosen. Truncated limits can be specified on many distributions, whose usual definition has an infinite support. 3 - Restrictions on the complexity of the problem: Generation of correlated random variables is not included

  13. Revisiting Coos Bay, Oregon: A re-examination of funginite-huminite relationships in Eocene subbituminous coals

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, Jennifer M.K. [Department of Earth and Space Sciences, Morehead State University, Morehead, KY (United States); Hower, James C. [University of Kentucky, Lexigton (United States). Center for Applied Energy Research

    2011-01-01

    Coal petrography has advanced significantly since Reinhardt Theissen and James Schopf pioneered the use of thin sections to examine coals from Coos Bay Oregon, and to many coal petrographers the nomenclature used in that study is irrelevant. The Schopf (1947) study was a ground-breaking examination of maceral relationships that need to be part of the working vocabulary of modern petrographers. To support this, a re-examination of the Coos Bay thin section collection was undertaken, using modern nomenclature for low-rank coals under reflected light. This particular collection was chosen in part because of the abundance of fungal material reported by Schopf. Fungal material in coal and its association with huminite/vitrinite macerals provides important information about the decompositional history of the coal and allows coal dominated by oxic processes to be differentiated from coal dominated by anoxic processes. In the Coos Bay samples, predominantly oxic intervals contain well-preserved fungi, including spores, sclerotia, and hyphae, while anoxic intervals contain no fungi. (author)

  14. Overview of an effective-medium approach to the reflection and refraction of light at a turbid colloidal half-space

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez-Reyes, Edahi; Barrera, Ruben G. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, Mexico Distrito Federal (Mexico); Garcia-Valenzuela, Augusto [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, Mexico Distrito Federal (Mexico)

    2012-06-15

    It has been recently shown that the effective electromagnetic bulk response of a dilute colloidal system, composed by a large collection of identical big spheres, located at random, is spatially dispersive (non-local). Here, we extend this effective-medium approach to the calculation of the reflection and transmission amplitudes of the same system but with a flat interface. We use an integral-equation approach for the calculation of the average electric field. The integral equation is solved within the effective-field approximation, by proposing a plane-wave solution with effective parameters that are calculated by solving a set of consistency equations. We obtain explicit expressions for the transmission and reflection amplitudes as a function of the filling fraction, the radius of the inclusions and the angle of incidence. We show and discuss numerical results for a system of silver particles. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Assessing reflective thinking and approaches to learning.

    Science.gov (United States)

    Dunn, Louise; Musolino, Gina M

    2011-01-01

    Facilitation of reflective practice is critical for the ongoing demands of health care practitioners. Reflective thinking concepts, grounded in the work of Dewey and Schön, emphasize critical reflection to promote transformation in beliefs and learning necessary for reflective practice. The Reflective Thinking Questionnaire (QRT) and Revised Study Process Questionnaire (RSPQ-2F) assess skill aspects of professional reasoning, with promise for measuring changes over time. The purpose of this study was to examine the reliability and responsiveness and the model validity of reflective thinking and approaches to learning measures for U.S. health professions students enrolled in entry-level occupational (MOT) and physical therapy (DPT) programs. This measurement study addressed reliability and responsiveness of two measures, the QRT and RSPQ-2F, for graduate health professionals. A convenience sample of 125 MOT and DPT students participated in the two-measure, test-retest investigation, with electronic data collection. Outcomes support the stability of the four-scale QRT (ICC 0.63 to 0.82) and the two-scale RSPQ-2F (ICC 0.91 and 0.87). Descriptive data supporting responsiveness are presented. With noted limitations, the results support the use of the QRT and RSPQ-2F measures to assess changes in reflective thinking and approaches to learning. Measurement of these learning outcomes furthers our understanding and knowledge about instructional strategies, development of professional reasoning, and fostering of self-directed learning within MOT and DPT programs.

  16. Thermal consequences of colour and near-infrared reflectance.

    Science.gov (United States)

    Stuart-Fox, Devi; Newton, Elizabeth; Clusella-Trullas, Susana

    2017-07-05

    The importance of colour for temperature regulation in animals remains controversial. Colour can affect an animal's temperature because all else being equal, dark surfaces absorb more solar energy than do light surfaces, and that energy is converted into heat. However, in reality, the relationship between colour and thermoregulation is complex and varied because it depends on environmental conditions and the physical properties, behaviour and physiology of the animal. Furthermore, the thermal effects of colour depend as much on absorptance of near-infrared ((NIR), 700-2500 nm) as visible (300-700 nm) wavelengths of direct sunlight; yet the NIR is very rarely considered or measured. The few available data on NIR reflectance in animals indicate that the visible reflectance is often a poor predictor of NIR reflectance. Adaptive variation in animal coloration (visible reflectance) reflects a compromise between multiple competing functions such as camouflage, signalling and thermoregulation. By contrast, adaptive variation in NIR reflectance should primarily reflect thermoregulatory requirements because animal visual systems are generally insensitive to NIR wavelengths. Here, we assess evidence and identify key research questions regarding the thermoregulatory function of animal coloration, and specifically consider evidence for adaptive variation in NIR reflectance.This article is part of the themed issue 'Animal coloration: production, perception, function and application'. © 2017 The Author(s).

  17. Development of paints with infrared radiation reflective properties

    Directory of Open Access Journals (Sweden)

    Eliane Coser

    2015-06-01

    Full Text Available AbstractLarge buildings situated in hot regions of the Globe need to be agreeable to their residents. Air conditioning is extensively used to make these buildings comfortable, with consequent energy consumption. Absorption of solar visible and infrared radiations are responsible for heating objects on the surface of the Earth, including houses and buildings. To avoid excessive energy consumption, it is possible to use coatings formulated with special pigments that are able to reflect the radiation in the near- infrared, NIR, spectrum. To evaluate this phenomenon an experimental study about the reflectivity of paints containing infrared-reflective pigments has been made. By irradiating with an IR source and by measuring the surface temperatures of the samples we evaluated: color according to ASTM D 2244-14, UV/VIS/NIR reflectance according to ASTM E 903-12 and thermal performance. Additionally, the spectral reflectance and the IR emittance were measured and the solar reflectance of the samples were calculated. The results showed that plates coated with paints containing IR-reflecting pigments displayed lower air temperature on the opposite side as compared to conventional coatings, indicating that they can be effective to reflect NIR and decrease the temperature of buildings when used in roofs and walls.

  18. A comparison of random walks in dependent random environments

    NARCIS (Netherlands)

    Scheinhardt, Willem R.W.; Kroese, Dirk

    2015-01-01

    Although the theoretical behavior of one-dimensional random walks in random environments is well understood, the actual evaluation of various characteristics of such processes has received relatively little attention. This paper develops new methodology for the exact computation of the drift in such

  19. The generalized vectorial laws of reflection and refraction

    International Nuclear Information System (INIS)

    Bhattacharjee, Pramode Ranjan

    2005-01-01

    This paper discloses two important discoveries. These are: (i) discovery of ambiguity in the well-established laws of reflection and refraction of light which have been in regular use for many years, and (ii) discovery of generalized vectorial laws of reflection and refraction of light. The existing definitions of angle of incidence, angle of reflection and angle of refraction are considered first. Each of these definitions is found to be ambiguous, not in compliance with the fundamental definition of angle in geometry. Two typical questions (one in the case of reflection and the other for refraction) have been addressed, which cannot be dealt with by using the existing laws of reflection and refraction of light. Thus, the existing laws of reflection and refraction of light seem to be ambiguous in respect of generality and their validity in a broad sense is questionable. With a view to removing the ambiguities, proper definitions of the above three angles are given first and then the statement of the generalized vectorial law of reflection (as well as that of refraction) has been offered

  20. The reflection component in NS LMXBs

    Directory of Open Access Journals (Sweden)

    D’Aí A.

    2014-01-01

    Full Text Available Thanks to the good spectral resolution and large effective area of the EPIC/PN instrument on board of XMM-Newton, we have at hand a large number of observations of accreting low-mass X-ray binaries, that allow for the fist time a comprehensive view on the characteristics of the reflection component at different accretion regimes and to probe the effects of a magnetosphere on its formation. We focus here on a comparative analysis of the reflection component from a series of spectroscopic studies on selected sources: 4U 1705-44, observed both in the soft and hard state, the pulsating ms pulsars SAX J1808.4-3658 and IGR J17511-3057, and the intermittent pulsar HETE J1900-2455. Although the sources can present very similar accretion rates and continuum shapes, the reflection parameters do not generally result the same, moreover the effect of a magnetosphere on the formation of the reflection component appears elusive.

  1. Reflection-type electromagnetically induced transparency analogue in terahertz metamaterials

    International Nuclear Information System (INIS)

    Ding Chun-Feng; Zhang Ya-Ting; Yao Jian-Quan; Xu De-Gang; Zhang Gui-Zhong; Sun Chong-Ling

    2014-01-01

    A reflection-type electromagnetically induced transparency (EIT) metamaterial is proposed, which is composed of a dielectric spacer sandwiched with metallic patterns and metallic plane. Experimental results of THz time domain spectrum (THz-TDS) exhibit a typical reflection of EIT at 0.865 THz, which are in excellent agreement with the full-wave simulations. A multi-reflection theory is adopted to analyze the physical mechanism of the reflection-type EIT, showing that the reflection-type EIT is a superposition of multiple reflection of the transmission EIT. Such a reflection-type EIT provides many applications based on the EIT effect, such as slow light devices and nonlinear elements. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  2. Acute effects of interval versus continuous endurance training on pulse wave reflection in healthy young men.

    Science.gov (United States)

    Hanssen, Henner; Nussbaumer, Monique; Moor, Christoph; Cordes, Mareike; Schindler, Christian; Schmidt-Trucksäss, Arno

    2015-02-01

    Our aim was to investigate the acute and 24-hour (h) effects of high-intensity interval training (HIIT) and moderate continuous training (MCT) on arterial pulse wave reflection, an established marker of arterial stiffness and cardiovascular risk. In a randomized cross-over design, 21 young healthy male participants performed a HIIT or a MCT on separate visits. Before and 5 (t5), 20 (t20), 35 (t35), and 50 (t50) minutes after the acute exercise bouts, the crude augmentation index (AIx) and the AIx at a set heart rate (AIx@75) were analysed by applanation tonometry. Starting 1 h post-exercise, both indices were captured over 24-h with an oscillometric monitoring device. AIx did not change significantly after MCT but declined progressively after HIIT, reaching significantly lower values compared to MCT at t35 (P = 0.045) and t50 (P = 0.008). AIx@75 increased after both acute exercise types but was higher after HIIT at t5 (P HIIT (P = 0.007) but not after MCT (P = 0.813). Exercise intensity affects pulse wave reflection, with different time courses for AIx and AIx@75 post-exercise. Although initially higher after HIIT, AIx@75 declines in the 24-h recovery period indicating more favourable effects on pulse wave reflection compared to MCT. This may result in substantial positive chronic training effects on arterial stiffness in health and cardiovascular disease. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  3. Do not resuscitate: reflections on an ethical dilemma.

    Science.gov (United States)

    Jones, Jeannie

    This is a reflective account of an ethical dilemma encountered while on placement on a cardiology ward. Reflection is a process which allows practitioners to reveal and expose thoughts, behaviours and feelings that are present at a particular time. All reflective models are based on the principle that purposeful reflection results in a better understanding and awareness, thus enhancing clinical practice (Driscoll and Teh 2001). The Gibbs' Reflective Cycle has been selected for its simplicity and ease of use to aid personal development. The dilemma was identified and analysed from a professional, ethical and legal perspective. Pseudonyms are used to maintain confidentiality and protect the identities of all parties involved.

  4. Tailoring diffuse reflectance of inhomogeneous films containing microplatelets

    Energy Technology Data Exchange (ETDEWEB)

    Slovick, Brian A., E-mail: brian.slovick@sri.com; Baker, John M.; Flom, Zachary; Krishnamurthy, Srini [Applied Optics Laboratory, SRI International, Menlo Park, California 94025 (United States)

    2015-10-05

    We develop an analytical model for calculating the diffuse reflectance of inhomogeneous films containing aligned microplatelets with diameters much greater than the wavelength. The scattering parameters are derived by modeling the platelets as one-dimensional thin films, and the overall diffuse reflectance of the slab is calculated using the Kubelka-Munk model. Our model predicts that reflection minima and maxima arising from coherent interference within the platelets are preserved in the diffuse reflectance of the disordered slab. Experimental validation of the model is provided by reflectance measurements (0.3–15 μm) of a solid aerosol film of aligned hexagonal boron nitride platelets.

  5. Signal-enhancement reflective pulse oximeter with Fresnel lens

    Science.gov (United States)

    Chung, Shuang-Chao; Sun, Ching-Cherng

    2016-09-01

    In this paper, a new reflective pulse oximeter is proposed and demonstrated with implanting a Fresnel lens, which enhances the reflected signal. An optical simulation model incorporated with human skin characteristics is presented to evaluate the capability of the Fresnel lens. In addition, the distance between the light emitting diode and the photodiode is optimized. Compared with the other reflective oximeters, the reflected signal light detected by the photodiode is enhanced to more than 140%.

  6. Fracture diagnostics with tube wave reflection logs

    International Nuclear Information System (INIS)

    Medlin, W.L.

    1991-01-01

    This paper reports on the Tube Wave Reflection Log (TWRL) which is acoustic logging method which provides information about the height, location and conductivity of hydraulically induced fractures behind perforated casing. The TWRL tool consists of a transmitter and closely spaced receiver. The transmitter is driven with a short, low frequency tone burst to generate long wavelength tube waves which are little attenuated in unperforated casing. They are partially reflected when they pass perforated intervals communicating with a hydraulically induced fracture. The tool listens for such reflections for 0.1 seconds following each excitation burst. As the tool is moved uphole at logging speed, the transmitter is excited at each foot of depth. VDL displays of the TWRL records provide reflection traces whose projections define the uppermost and lower-most perforations communicating with the fracture. The strength of the reflections depends on the ease of fluid flow into the fracture and thus, is an indicator of fracture conductivity

  7. Ultraviolet reflectance by the cere of raptors

    Science.gov (United States)

    Mougeot, François; Arroyo, Beatriz E

    2006-01-01

    Ultraviolet (UV) signals have been shown to play key roles in social and sexual signalling in birds. Using a spectrophotometer, we analysed the colour of the cere (skin above the beak) of a diurnal raptor, the Montagu's harrier (Circus pygargus), and show that it reflects in the UV part of the spectrum. The cere is a well-known sexual signal in raptors, with carotenoid based pigmentation being indicative of quality. We thus hypothesized that UV reflectance also signals quality. Accordingly, we found that in our sample of wild males, the location of the UV peak was related to the orangeness of cere and correlated with male body mass and condition (mass corrected for size). Also, males with brighter UV were mated to females that laid earlier, as expected if UV reflectance relates to a male's quality and attractiveness. Future studies should investigate the relationships between UV reflectance and carotenoid pigmentation of cere, and test how UV reflectance influences mate choice. PMID:17148356

  8. Do Scaffolding Tools Improve Reflective Writing in Professional Portfolios? A Content Analysis of Reflective Writing in an Advanced Preparation Program

    Science.gov (United States)

    Houston, Cynthia R.

    2016-01-01

    Reflective practice is an important skill that teachers must develop to be able to assess the effectiveness of their teaching and modify their instructional behavior. In many education programs reflective narratives, which are often part of teaching portfolios, are intended to assess students' abilities in these areas. Research on reflectivity in…

  9. Reflections on Teaching Financial Statement Analysis

    Science.gov (United States)

    Entwistle, Gary

    2015-01-01

    In her 2011 article "Towards a 'scholarship of teaching and learning': The individual and the communal journey," Ursula Lucas calls for more critical reflection on individual teaching experiences and encourages sharing such experiences with the wider academy. In this spirit Gary Entwistle reflects upon his experiences teaching financial…

  10. Reflections of a Latino Associate Professor

    Science.gov (United States)

    Peguero, Anthony A.

    2018-01-01

    The following reflection essay is about my experiences as a Latino Associate Professor who focuses on criminology, youth violence, juvenile justice, and the associated disparities with race, ethnicity, and immigration. I reflect about the "race and justice" job market, pursuing and establishing a Latina/o Criminology working group, often…

  11. Timing the total reflection of light

    International Nuclear Information System (INIS)

    Chauvat, Dominique; Bonnet, Christophe; Dunseath, Kevin; Emile, Olivier; Le Floch, Albert

    2005-01-01

    We have identified for the first time the absolute delay at total reflection, envisioned by Newton. We show that there are in fact two divergent Wigner delays, depending on the polarisation of the incident light. These measurements give a new insight on the passage from total reflection to refraction

  12. Reflective Healthcare Systems : Micro-Cycle of Self-Reflection to empower users

    NARCIS (Netherlands)

    Jimenez Garcia, J.C.; Romero Herrera, N.A.; Keyson, D.V.; Havinga, P.

    2014-01-01

    Data collection and reflection are considered an integrated process in Personal Informatics to help users take action towards changing behaviour. Facilitating the collection and visualization of large data sets has been a major technical challenge to guarantee meaningful and effortless information

  13. Reflection Negative Kernels and Fractional Brownian Motion

    Directory of Open Access Journals (Sweden)

    Palle E. T. Jorgensen

    2018-06-01

    Full Text Available In this article we study the connection of fractional Brownian motion, representation theory and reflection positivity in quantum physics. We introduce and study reflection positivity for affine isometric actions of a Lie group on a Hilbert space E and show in particular that fractional Brownian motion for Hurst index 0 < H ≤ 1 / 2 is reflection positive and leads via reflection positivity to an infinite dimensional Hilbert space if 0 < H < 1 / 2 . We also study projective invariance of fractional Brownian motion and relate this to the complementary series representations of GL 2 ( R . We relate this to a measure preserving action on a Gaussian L 2 -Hilbert space L 2 ( E .

  14. Reflective and refractive objects for mixed reality.

    Science.gov (United States)

    Knecht, Martin; Traxler, Christoph; Winklhofer, Christoph; Wimmer, Michael

    2013-04-01

    In this paper, we present a novel rendering method which integrates reflective or refractive objects into a differential instant radiosity (DIR) framework usable for mixed-reality (MR) applications. This kind of objects are very special from the light interaction point of view, as they reflect and refract incident rays. Therefore they may cause high-frequency lighting effects known as caustics. Using instant-radiosity (IR) methods to approximate these high-frequency lighting effects would require a large amount of virtual point lights (VPLs) and is therefore not desirable due to real-time constraints. Instead, our approach combines differential instant radiosity with three other methods. One method handles more accurate reflections compared to simple cubemaps by using impostors. Another method is able to calculate two refractions in real-time, and the third method uses small quads to create caustic effects. Our proposed method replaces parts in light paths that belong to reflective or refractive objects using these three methods and thus tightly integrates into DIR. In contrast to previous methods which introduce reflective or refractive objects into MR scenarios, our method produces caustics that also emit additional indirect light. The method runs at real-time frame rates, and the results show that reflective and refractive objects with caustics improve the overall impression for MR scenarios.

  15. Properties of interstellar dust in reflection nebulae

    International Nuclear Information System (INIS)

    Sellgren, K.

    1988-01-01

    Observations of interstellar dust in reflection nebulae are the closest analog in the interstellar medium to studies of cometary dust in our solar system. The presence of a bright star near the reflection nebula dust provides the opportunity to study both the reflection and emission characteristics of interstellar dust. At 0.1 to 1 micrometer, the reflection nebula emission is due to starlight scattered by dust. The albedo and scattering phase function of the dust is determined from observations of the scattered light. At 50 to 200 micrometers, thermal emission from the dust in equilibrium with the stellar radiation field is observed. The derived dust temperature determines the relative values of the absorption coefficient of the dust at wavelengths where the stellar energy is absorbed and at far infrared wavelengths where the absorbed energy is reradiated. These emission mechanisms directly relate to those seen in the near and mid infrared spectra of comets. In a reflection nebula the dust is observed at much larger distances from the star than in our solar system, so that the equilibrium dust temperature is 50 K rather than 300 K. Thus, in reflection nebulae, thermal emission from dust is emitted at 50 to 200 micrometer

  16. Self-reflection and academic performance: is there a relationship?

    NARCIS (Netherlands)

    M.D.N. Lew (Magdeleine D.N.); H.G. Schmidt (Henk)

    2011-01-01

    textabstractThe purposes of the present study were two-fold: first, to evaluate whether reflection journal writing was effective in promoting self-reflection and learning, and whether students become better at self-reflection if they engage continuously in reflection journal writing. To that end,

  17. Exploring Reflective Means to Handle Plagiarism

    Science.gov (United States)

    Dalal, Nikunj

    2016-01-01

    Plagiarism has become widespread in the university teaching environment. This article presents practical wisdom from several years of experience handling plagiarism in two Information Systems (IS) courses with the exploratory use of reflective means such as dialogues and essays. There has been very little work on the use of reflective approaches…

  18. THE VARIABLE REFLECTION NEBULA CEPHEUS A EAST

    International Nuclear Information System (INIS)

    Hodapp, Klaus W.; Bressert, Eli

    2009-01-01

    We report K'-band imaging observations of the reflection nebula associated with Cepheus A East covering the time interval from 1990 to 2004. Over this time the reflection nebula shows variations of flux distribution, which we interpret as the effect of inhomogeneous and varying extinction in the light path from the illuminating source HW2 to the reflection nebula. The obscuring material is located within typical distances of ∼ 10 AU from the illuminating source.

  19. Quantifiers for randomness of chaotic pseudo-random number generators.

    Science.gov (United States)

    De Micco, L; Larrondo, H A; Plastino, A; Rosso, O A

    2009-08-28

    We deal with randomness quantifiers and concentrate on their ability to discern the hallmark of chaos in time series used in connection with pseudo-random number generators (PRNGs). Workers in the field are motivated to use chaotic maps for generating PRNGs because of the simplicity of their implementation. Although there exist very efficient general-purpose benchmarks for testing PRNGs, we feel that the analysis provided here sheds additional didactic light on the importance of the main statistical characteristics of a chaotic map, namely (i) its invariant measure and (ii) the mixing constant. This is of help in answering two questions that arise in applications: (i) which is the best PRNG among the available ones? and (ii) if a given PRNG turns out not to be good enough and a randomization procedure must still be applied to it, which is the best applicable randomization procedure? Our answer provides a comparative analysis of several quantifiers advanced in the extant literature.

  20. Student Chemical Engineering Reflective ePortfolios--ChE Student Perceptions of Learning from Reflective ePortfolio Creation

    Science.gov (United States)

    Cherrstrom, Catherine A.; Raisor, Cindy; Fowler, Debra

    2015-01-01

    Engineering educators and employers value and prioritize communication skills, but developing and assessing such skills in engineering programs is challenging. Reflective ePortfolios provide opportunities to enhance communication skills. The purpose of this three-­year qualitative case study was to investigate the use of reflective ePortfolios in…

  1. Metacognitive Reflection and Insight Therapy for Early Psychosis: A preliminary study of a novel integrative psychotherapy.

    Science.gov (United States)

    Vohs, Jenifer L; Leonhardt, Bethany L; James, Alison V; Francis, Michael M; Breier, Alan; Mehdiyoun, Nikki; Visco, Andrew C; Lysaker, Paul H

    2018-05-01

    Poor insight impedes treatment in early phase psychosis (EPP). This manuscript outlines preliminary findings of an investigation of the novel metacognitively oriented integrative psychotherapy, Metacognitive Reflection and Insight Therapy, for individuals with early phase psychosis (MERIT-EP). Twenty adults with EPP and poor insight were randomized to either six months of MERIT-EP or treatment as usual (TAU). Therapists were trained and therapy was successfully delivered under routine, outpatient conditions. Insight, assessed before and after treatment, revealed significant improvement for the MERIT-EP, but not TAU, group. These results suggest MERIT-EP is feasible to deliver, accepted by patients, and leads to clinically significant improvements in insight. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Directional statistics-based reflectance model for isotropic bidirectional reflectance distribution functions.

    Science.gov (United States)

    Nishino, Ko; Lombardi, Stephen

    2011-01-01

    We introduce a novel parametric bidirectional reflectance distribution function (BRDF) model that can accurately encode a wide variety of real-world isotropic BRDFs with a small number of parameters. The key observation we make is that a BRDF may be viewed as a statistical distribution on a unit hemisphere. We derive a novel directional statistics distribution, which we refer to as the hemispherical exponential power distribution, and model real-world isotropic BRDFs as mixtures of it. We derive a canonical probabilistic method for estimating the parameters, including the number of components, of this novel directional statistics BRDF model. We show that the model captures the full spectrum of real-world isotropic BRDFs with high accuracy, but a small footprint. We also demonstrate the advantages of the novel BRDF model by showing its use for reflection component separation and for exploring the space of isotropic BRDFs.

  3. Solid-State Random Lasers

    CERN Document Server

    Noginov, Mikhail A

    2005-01-01

    Random lasers are the simplest sources of stimulated emission without cavity, with the feedback provided by scattering in a gain medium. First proposed in the late 60’s, random lasers have grown to a large research field. This book reviews the history and the state of the art of random lasers, provides an outline of the basic models describing their behavior, and describes the recent advances in the field. The major focus of the book is on solid-state random lasers. However, it also briefly describes random lasers based on liquid dyes with scatterers. The chapters of the book are almost independent of each other. So, the scientists or engineers interested in any particular aspect of random lasers can read directly the relevant section. Researchers entering the field of random lasers will find in the book an overview of the field of study. Scientists working in the field can use the book as a reference source.

  4. Simulating polarized light scattering in terrestrial snow based on bicontinuous random medium and Monte Carlo ray tracing

    International Nuclear Information System (INIS)

    Xiong, Chuan; Shi, Jiancheng

    2014-01-01

    To date, the light scattering models of snow consider very little about the real snow microstructures. The ideal spherical or other single shaped particle assumptions in previous snow light scattering models can cause error in light scattering modeling of snow and further cause errors in remote sensing inversion algorithms. This paper tries to build up a snow polarized reflectance model based on bicontinuous medium, with which the real snow microstructure is considered. The accurate specific surface area of bicontinuous medium can be analytically derived. The polarized Monte Carlo ray tracing technique is applied to the computer generated bicontinuous medium. With proper algorithms, the snow surface albedo, bidirectional reflectance distribution function (BRDF) and polarized BRDF can be simulated. The validation of model predicted spectral albedo and bidirectional reflectance factor (BRF) using experiment data shows good results. The relationship between snow surface albedo and snow specific surface area (SSA) were predicted, and this relationship can be used for future improvement of snow specific surface area (SSA) inversion algorithms. The model predicted polarized reflectance is validated and proved accurate, which can be further applied in polarized remote sensing. -- Highlights: • Bicontinuous random medium were used for real snow microstructure modeling. • Photon tracing technique with polarization status tracking ability was applied. • SSA–albedo relationship of snow is close to that of sphere based medium. • Validation of albedo and BRDF showed good results. • Validation of polarized reflectance showed good agreement with experiment data

  5. Manifestation of Crystal Lattice Distortions in the IR Reflection Spectra of Abrasion-Treated ZnSe Ceramics

    Science.gov (United States)

    Sitnikova, V. E.; Dunaev, A. A.; Mamalimov, R. I.; Pakhomov, P. M.; Khizhnyak, S. D.; Chmel, A. E.

    2017-07-01

    The Fourier IR reflection spectra of ZnSe ceramics prepared by hot pressing (HP), physical vapor deposition (PVD), and PVD combined with hot isostatic pressing (HIP) are presented. The optical constants of polished and dry-ground specimens were used for comparison. The grinding treatment simulated the erosion of the outer surface of optical elements made of zinc selenide under the influence of solid dust particles and deposits. In the polished specimens residual stresses showed up in the IR reflection spectra of the ZnSePVD and ZnSeHIP ceramics, which had well-defined orientation of grains, but were not present in the spectra of the ZnSeHIP ceramics as a result of mutual compensation of the stresses in the randomly oriented grains of the material. The stresses, which appeared as a shift of the absorption bands calculated by the Kramers-Kronig method, increased significantly after abrasive treatment of the specimens. For all the treated ceramics the intensity of the absorption bands resulting from the anharmonicity of the vibrations in the distorted crystal lattice increased by several times. The last effect also depends on the production prehistory of the ceramics.

  6. Random walks, random fields, and disordered systems

    CERN Document Server

    Černý, Jiří; Kotecký, Roman

    2015-01-01

    Focusing on the mathematics that lies at the intersection of probability theory, statistical physics, combinatorics and computer science, this volume collects together lecture notes on recent developments in the area. The common ground of these subjects is perhaps best described by the three terms in the title: Random Walks, Random Fields and Disordered Systems. The specific topics covered include a study of Branching Brownian Motion from the perspective of disordered (spin-glass) systems, a detailed analysis of weakly self-avoiding random walks in four spatial dimensions via methods of field theory and the renormalization group, a study of phase transitions in disordered discrete structures using a rigorous version of the cavity method, a survey of recent work on interacting polymers in the ballisticity regime and, finally, a treatise on two-dimensional loop-soup models and their connection to conformally invariant systems and the Gaussian Free Field. The notes are aimed at early graduate students with a mod...

  7. Memory: Enduring Traces of Perceptual and Reflective Attention

    Science.gov (United States)

    Chun, Marvin M.; Johnson, Marcia K.

    2011-01-01

    Attention and memory are typically studied as separate topics, but they are highly intertwined. Here we discuss the relation between memory and two fundamental types of attention: perceptual and reflective. Memory is the persisting consequence of cognitive activities initiated by and/or focused on external information from the environment (perceptual attention) and initiated by and/or focused on internal mental representations (reflective attention). We consider three key questions for advancing a cognitive neuroscience of attention and memory: To what extent do perception and reflection share representational areas? To what extent are the control processes that select, maintain, and manipulate perceptual and reflective information subserved by common areas and networks? During perception and reflection, to what extent are common areas responsible for binding features together to create complex, episodic memories and for reviving them later? Considering similarities and differences in perceptual and reflective attention helps integrate a broad range of findings and raises important unresolved issues. PMID:22099456

  8. Memory: enduring traces of perceptual and reflective attention.

    Science.gov (United States)

    Chun, Marvin M; Johnson, Marcia K

    2011-11-17

    Attention and memory are typically studied as separate topics, but they are highly intertwined. Here we discuss the relation between memory and two fundamental types of attention: perceptual and reflective. Memory is the persisting consequence of cognitive activities initiated by and/or focused on external information from the environment (perceptual attention) and initiated by and/or focused on internal mental representations (reflective attention). We consider three key questions for advancing a cognitive neuroscience of attention and memory: to what extent do perception and reflection share representational areas? To what extent are the control processes that select, maintain, and manipulate perceptual and reflective information subserved by common areas and networks? During perception and reflection, to what extent are common areas responsible for binding features together to create complex, episodic memories and for reviving them later? Considering similarities and differences in perceptual and reflective attention helps integrate a broad range of findings and raises important unresolved issues. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. Quantumness, Randomness and Computability

    International Nuclear Information System (INIS)

    Solis, Aldo; Hirsch, Jorge G

    2015-01-01

    Randomness plays a central role in the quantum mechanical description of our interactions. We review the relationship between the violation of Bell inequalities, non signaling and randomness. We discuss the challenge in defining a random string, and show that algorithmic information theory provides a necessary condition for randomness using Borel normality. We close with a view on incomputablity and its implications in physics. (paper)

  10. Matter reflects Antimatter

    CERN Document Server

    Bianconi, A.; Cristiano, A.; Leali, M.; Lodi Rizzini, E.; Venturelli, L.; Zurlo, N.

    2008-01-01

    It is common belief that the interaction between antimatter and ordinary solid matter is dominated by annihilation. However, non-destructive processes may play a relevant role too. One century ago E. Rutherford wrote about the "diffuse reflection" of alpha and beta particles by thin layers of different metals: "The observations ... of Geiger and Marsden on the scattering of alpha rays indicate that some of the alpha particles must suffer a deflexion of more than a right angle at a single encounter.... It will be shown that the main deductions from the theory are independent of whether the central charge is supposed to be positive or negative". Although the theory of electromagnetic scattering is in first approximation independent of the relative sign of the colliding particles, in the case where projectile antiprotons are shot against a wall of solid matter the Rutherford diffuse reflection mechanism competes with the annihilation process. So it is not obvious at all that a relevant part of an antiproton beam...

  11. Cognitive reflection vs. calculation in decision making

    OpenAIRE

    Sinayev, Aleksandr; Peters, Ellen

    2015-01-01

    Scores on the three-item Cognitive Reflection Test (CRT) have been linked with dual-system theory and normative decision making (Frederick, 2005). In particular, the CRT is thought to measure monitoring of System 1 intuitions such that, if cognitive reflection is high enough, intuitive errors will be detected and the problem will be solved. However, CRT items also require numeric ability to be answered correctly and it is unclear how much numeric ability vs. cognitive reflection contributes t...

  12. Cognitive Reflection Versus Calculation in Decision Making

    OpenAIRE

    Aleksandr eSinayev; Ellen ePeters

    2015-01-01

    Scores on the three-item Cognitive Reflection Test (CRT) have been linked with dual-system theory and normative decision making (Frederick, 2005). In particular, the CRT is thought to measure monitoring of System 1 intuitions such that, if cognitive reflection is high enough, intuitive errors will be detected and the problem will be solved. However, CRT items also require numeric ability to be answered correctly and it is unclear how much numeric ability vs. cognitive reflection contributes t...

  13. Self-correcting random number generator

    Science.gov (United States)

    Humble, Travis S.; Pooser, Raphael C.

    2016-09-06

    A system and method for generating random numbers. The system may include a random number generator (RNG), such as a quantum random number generator (QRNG) configured to self-correct or adapt in order to substantially achieve randomness from the output of the RNG. By adapting, the RNG may generate a random number that may be considered random regardless of whether the random number itself is tested as such. As an example, the RNG may include components to monitor one or more characteristics of the RNG during operation, and may use the monitored characteristics as a basis for adapting, or self-correcting, to provide a random number according to one or more performance criteria.

  14. Uses of Technology to Support Reflective Teaching Practices

    Science.gov (United States)

    Brent, Wayne

    2010-01-01

    This dissertation researched and reported on how technology was used to facilitate and inform reflective teaching practices. It also identified the characteristics of benefits and barriers in using technology for teaching and reflection. The study, descriptive in nature, was designed to determine the reflective practices of instructors and how…

  15. Using reflectance spectroscopy to predict beef tenderness.

    Science.gov (United States)

    Bowling, M B; Vote, D J; Belk, K E; Scanga, J A; Tatum, J D; Smith, G C

    2009-05-01

    A study was conducted to determine if reflectance measurements made in the near-infrared region of the spectrum were additive to reflectance measurements made in the visible region of the spectrum for predicting Warner-Bratzler shear force (WBSF) values. Eighty seven strip loins were collected following fabrication over 3d at a commercial beef processing facility from heifer carcasses with Slight or Traces marbling scores. Spectroscopic measurements were made at approximately 50h postmortem using a Hunter-Lab UltraScan. Subsequently, all strip loins were aged for 14d, cooked to an internal temperature of 70°C, and sheared to obtain WBSF values. Reflectance measurements obtained in the near-infrared region of the spectrum were correlated with WBSF values, however, these measurements were not additive to the predictive ability of reflectance measurements (R(2) values did not differ) made in the visible portion of the spectrum when the use of broad-band wavelength filters were simulated. It was therefore determined, that both the visible and near-infrared spectra measure reflectance and that both methods are acceptable methods of tenderness prediction.

  16. Effects of force reflection on servomanipulator task performance

    International Nuclear Information System (INIS)

    Draper, J.V.; Moore, W.E.; Herndon, J.N.; Weil, B.S.

    1986-01-01

    This paper reports results of a testing program that assessed the impact of force reflection on servomanipulator task performance. The testing program compared three force-reflection levels: 4 to 1 (four units of force on the slave produce one unit of force at the master controller), 1 to 1, and infinity to 1 (no force reflection). Time required to complete tasks, rate of occurrence of errors, the maximum force applied to task components, and variability in forces during completion of representative remote handling tasks were used as dependent variables. Operators exhibited lower error rates, lower peak forces, and more consistent application of forces using force reflection than they did without it. These data support the hypothesis that force reflection provides useful information for servomanipulator operators

  17. Direct observation of ballistic Andreev reflection

    Science.gov (United States)

    Klapwijk, T. M.; Ryabchun, S. A.

    2014-12-01

    An overview is presented of experiments on ballistic electrical transport in inhomogeneous superconducting systems which are controlled by the process of Andreev reflection. The initial experiments based on the coexistence of a normal phase and a superconducting phase in the intermediate state led to the concept itself. It was followed by a focus on geometrically inhomogeneous systems like point contacts, which provided a very clear manifestation of the energy and direction dependence of the Andreev reflection process. The point contacts have recently evolved towards the atomic scale owing to the use of mechanical break-junctions, revealing a very detailed dependence of Andreev reflection on the macroscopic phase of the superconducting state. In present-day research, the superconducting in homogeneity is constructed by clean room technology and combines superconducting materials, for example, with low-dimensional materials and topological insulators. Alternatively, the superconductor is combined with nano-objects, such as graphene, carbon nanotubes, or semiconducting nanowires. Each of these "inhomogeneous systems" provides a very interesting range of properties, all rooted in some manifestation of Andreev reflection.

  18. Wave-equation reflection traveltime inversion

    KAUST Repository

    Zhang, Sanzong

    2011-01-01

    The main difficulty with iterative waveform inversion using a gradient optimization method is that it tends to get stuck in local minima associated within the waveform misfit function. This is because the waveform misfit function is highly nonlinear with respect to changes in the velocity model. To reduce this nonlinearity, we present a reflection traveltime tomography method based on the wave equation which enjoys a more quasi-linear relationship between the model and the data. A local crosscorrelation of the windowed downgoing direct wave and the upgoing reflection wave at the image point yields the lag time that maximizes the correlation. This lag time represents the reflection traveltime residual that is back-projected into the earth model to update the velocity in the same way as wave-equation transmission traveltime inversion. No travel-time picking is needed and no high-frequency approximation is assumed. The mathematical derivation and the numerical examples are presented to partly demonstrate its efficiency and robustness. © 2011 Society of Exploration Geophysicists.

  19. Optical Reflectance Measurements for Commonly Used Reflectors

    Science.gov (United States)

    Janecek, Martin; Moses, William W.

    2008-08-01

    When simulating light collection in scintillators, modeling the angular distribution of optical light reflectance from surfaces is very important. Since light reflectance is poorly understood, either purely specular or purely diffuse reflectance is generally assumed. In this paper we measure the optical reflectance distribution for eleven commonly used reflectors. A 440 nm, output power stabilized, un-polarized laser is shone onto a reflector at a fixed angle of incidence. The reflected light's angular distribution is measured by an array of silicon photodiodes. The photodiodes are movable to cover 2pi of solid angle. The light-induced current is, through a multiplexer, read out with a digital multimeter. A LabVIEW program controls the motion of the laser and the photodiode array, the multiplexer, and the data collection. The laser can be positioned at any angle with a position accuracy of 10 arc minutes. Each photodiode subtends 6.3deg, and the photodiode array can be positioned at any angle with up to 10 arc minute angular resolution. The dynamic range for the current measurements is 10 5:1. The measured light reflectance distribution was measured to be specular for several ESR films as well as for aluminum foil, mostly diffuse for polytetrafluoroethylene (PTFE) tape and titanium dioxide paint, and neither specular nor diffuse for Lumirrorreg, Melinexreg and Tyvekreg. Instead, a more complicated light distribution was measured for these three materials.

  20. Distribution and Thermal Maturity of Devonian Carbonate Reservoir Solid Bitumen in Desheng Area of Guizhong Depression, South China

    Directory of Open Access Journals (Sweden)

    Yuguang Hou

    2017-01-01

    Full Text Available The distribution of solid bitumen in the Devonian carbonate reservoir from well Desheng 1, Guizhong Depression, was investigated by optical microscope and hydrocarbon inclusions analysis. Vb and chemical structure indexes measured by bitumen reflectance, laser Raman microprobe (LRM, and Fourier transform infrared spectroscopy (FTIR were carried out to determine the thermal maturity of solid bitumen. Based on the solid bitumen thermal maturity, the burial and thermal maturity history of Devonian carbonate reservoir were reconstructed by basin modeling. The results indicate that the fractures and fracture-related dissolution pores are the main storage space for the solid bitumen. The equivalent vitrinite reflectance of solid bitumen ranges from 3.42% to 4.43% converted by Vb (% and LRM. The infrared spectroscopy analysis suggests that there are no aliphatic chains detected in the solid bitumen which is rich in aromatics C=C chains (1431–1440 cm−1. The results of Vb (%, LRM, and FTIR analysis demonstrate that the solid bitumen has experienced high temperature and evolved to the residual carbonaceous stage. The thermal evolution of Devonian reservoirs had experienced four stages. The Devonian reservoirs reached the highest reservoir temperature 210–260°C during the second rapid burial-warming stage, which is the main period for the solid bitumen formation.