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Sample records for understand crud formation

  1. Study of Crud Formation Using One Stage Mixer Settler for U-Th Extraction

    International Nuclear Information System (INIS)

    Busron-Masduki; Mashudi; Didiek-Herhady, R; Endang-Susiantini

    2000-01-01

    It was carried out solvent extraction of used fuel simulation solution ofU-Th using one stage of mixer settler. The ratio of U/Th was 1/9. Thesolution of U- Th and extractant of 30% TBP diluted in the diluent ofn-dodecane filled in the mixer chamber with the ratio of 1/1 then stirred.The first experiment determined equilibrium time and optimum rpm and thensearched the influenced parameter of crud formation of thorium, zirconium(fission product), phosphate acid, butanol, bentonite powder (represent offines solid), ferrum, silicium according to the TBP degradation of DBP.Zirconium and thorium are significant parameter of crud formation. Theequilibrium time was 1.5 hour, optimum rpm was 1800. The weightest crud wasobtained related to the cumulative parameter which result of 250 gram crud.According to this result and for radiation dose of 1 watt, the extractantmust be regenerated before exceed 48 days to hold the crud formation whichdisturbance the extraction process. (author)

  2. Crud handling circuit

    International Nuclear Information System (INIS)

    Smith, J.C.; Manuel, R.J.; McAllister, J.E.

    1981-01-01

    A process for handling the problems of crud formation during the solvent extraction of wet-process phosphoric acid, e.g. for uranium and rare earth removal, is described. It involves clarification of the crud-solvent mixture, settling, water washing the residue and treatment of the crud with a caustic wash to remove and regenerate the solvent. Applicable to synergistic mixtures of dialkylphosphoric acids and trialkylphosphine oxides dissolved in inert diluents and more preferably to the reductive stripping technique. (U.K.)

  3. Literature Review: Crud Formation at the Liquid/Liquid Interface of TBP-Based Solvent-Extraction Processes

    Energy Technology Data Exchange (ETDEWEB)

    Delegard, Calvin H.; Casella, Amanda J.

    2016-09-30

    This report summarizes the literature reviewed on crud formation at the liquid:liquid interface of solvent extraction processes. The review is focused both on classic PUREX extraction for industrial reprocessing, especially as practiced at the Hanford Site, and for those steps specific to plutonium purification that were used at the Plutonium Reclamation Facility (PRF) within the Plutonium Finishing Plant (PFP) at the Hanford Site.

  4. Crud formation evaluation at the advanced fuel operating in Angra-1 NPP

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Diego; Palheiros, Franklin; Gomes, Sydney, E-mail: franklin@inb.gov.br, E-mail: diegogomez@inb.gov.br, E-mail: sydney@inb.gov.br [Indústrias Nucleares do Brasil (INB), Resende, RJ (Brazil). Superintendência de Engenharia do Combustível

    2017-07-01

    In nuclear engineering, 'crud' is a technical term. It stands for Chalk River Unidentified Deposit, originally found on the cladding surface of some fuel rods in the referred canadian reactor, for which it was named. The deposit can be flaky, porous, or hard depending on its chemical composition. In most cases, it reduces the power output of nuclear reactors - the deposits absorb boron and the neutrons that keep the fission reaction going, as well lead to a more corrosion scenario by increasing the oxide/metal interface surface temperature. This issue might been a concern at Angra 1 where many design alterations have been performed in the new Fuel assembly design. The so called 16NGF has a smaller fuel rod diameter, different burnable absorber - gadolinium instead of pyrex borosilicate glass, hydraulic mismatch compared to 16STD fuel, new IFM grids, higher FDeltaH and several other characteristics. All those features lead to a increase in the subcooled boiling rates, which might favour particles depositions in fuel cladding forming the undesired Crud deposits. In order to evaluate how those implementations could impact negatively the new fuel performance at Angra 1, a study has ben carried out using Thermal Hydraulic calculations. With that, an existing methodology was used to assess the associated risks and what could be the done to mitigate further development of crud in 16NGF Fuel in Angra 1. (author)

  5. Modeling chemistry in PWR fuel crud

    International Nuclear Information System (INIS)

    PWR fuel crud arises from deposition of corrosion products in the coolant on clad surfaces in the core. These deposits form a porous layer through which water must pass to provide effective heat transfer from the clad surface. The usual heat transfer mechanism is by wick boiling in which water passing through the porous crud is converted to steam that escapes through steam chimneys in the deposit. This conversion of water into steam within the deposit means that dilute solutions in the bulk coolant become concentrated in the crud and this can lead to precipitation of species such as lithium borates, ZnO and Zn-silicates. Such precipitation processes may lead to problems such as crud induced power shifts (CIPS), formally known as axial off-set anomaly (AOA), or crud induced localised corrosion (CILC) of the clad, that has led to cladding failures. These precipitation processes also hinder heat transfer and can lead to hot spots on the clad surfaces that are potentially damaging. Questions such as what should be the plant limits on Zn, Si, B and Li to prevent such problems, and how should these be controlled during the cycle, are not easy to answer. With several new designs of PWR proposing high power density cores and therefore greater subcooled nucleate boiling, and with existing plants still up-rating their cores, these questions are likely to become more important in the future. It is therefore important to understand the relationship between coolant chemistry (Zn, Si, Li, B levels) and the chemistry within fuel crud. The bulk and crud chemistry are coupled along with the bulk and local heat transfer processes. This coupling of chemistry and heat transfer makes this a particularly difficult problem to investigate theoretically although the authors have previously achieved this using a number of one dimensional heat and mass transfer models. This paper discusses a new approach to this problem using finite element methods to solve the relevant coupled chemistry and

  6. Mobile crud and transportation of radioactivity in BWR

    Energy Technology Data Exchange (ETDEWEB)

    Hermansson, H-P. [Studsvik Nuclear AB, Nykoping (Sweden); LTU, Div. of Chemical Engineering, Lulea (Sweden); Hagg, J. [Ringhals AB, Varobacka (Sweden)

    2010-07-01

    Mobile crud is here referred to as a generic term for all types of particles that occur in the reactor water in BWRs and that are able to carry radioactivity. Previous results in this on-going series of studies in Swedish BWRs suggest that there are particles of different origins and function. A share may come from fuel crud and others may come from detachment, precipitation and dissolution processes in different parts of the BWR primary system, as well as from other system parts, such as the turbine/condenser. In addition, crud particles in this sense may come from purely mechanical processes such as degradation of graphite containing parts of the control rod drives. Therefore, the overall aim was to evaluate which particles are responsible for the transportation and distribution of radioactivity and also to clarify the chemical conditions under which they are formed. Furthermore the aim was to draw conclusions about how the chemistry would be like in order to avoid or at least minimize the formation of radioactivity distributing particles. A specific objective has also been to look into the importance of particle size for spreading of radioactivity in the primary system. Different types of crud particles are likely to have different characteristics in terms of function associated with transportation of radioactivity. The fuel crud is radioactive from the source and other types of crud can via surface processes, co-precipitation and other chemical and mechanical processes potentially affect the distribution of radioactivity in the primary system. In order to predict how operating parameters (e.g. stable, full power operation and scram) and chemical parameters (NWC/HWC/Zn, etc.) will affect the activity build-up on the system surfaces, it is important to know how the different types of crud are affected by these and related parameters. Fuel crud fixed on cladding ring samples, as well as mobile crud from the reactor water captured on filters, were examined by

  7. CREDs, CRUDs, and Catholic scandals:

    DEFF Research Database (Denmark)

    Turpin, Hugh; Andersen, Marc Malmdorf; Lanman, Jonathan

    2018-01-01

    , perceived “religious hypocrisy” (forthwith credibility-undermining displays or CRUDs), as a factor in the rejection of religion. However, there is currently little causal evidence on whether behaviors of either kind displayed by religious authorities directly affect pre-existing religious belief...

  8. Proof-of-principle of high-fidelity coupled CRUD deposition and cycle depletion simulation

    International Nuclear Information System (INIS)

    Walter, Daniel J.; Kendrick, Brian K.; Petrov, Victor; Manera, Annalisa; Collins, Benjamin; Downar, Thomas

    2015-01-01

    A multiphysics framework for the high-fidelity simulation of CRUD deposition is developed to better understand the coupled physics and their respective feedback mechanisms. This framework includes the primary physics of lattice depletion, computational fluid dynamics, and CRUD chemistry. The three physics are coupled together via the operator-splitting technique, where predictor–corrector and fixed-point iteration schemes are utilized to converge the nonlinear solution. High-fidelity simulations may provide a means to predict and assess potential operating issues, including CRUD induced power shift and CRUD induced localized corrosion, known as CIPS and CILC, respectively. As a proof-of-principle, a coupled 500-day cycle depletion simulation of a pressurized water reactor fuel pin cell was performed using the coupled code suite; a burnup of 31 MWd/kgHM was reached. The simulation recreated the classic striped CRUD pattern often seen on pulled fuel rods containing CRUD. It is concluded that the striping is caused by the flow swirl induced by spacer grid mixing vanes. Two anti-correlated effects contribute to the striping: (1) the flow swirl yields significant azimuthal temperature variations, which impact the locations where CRUD deposits, and (2) the flow swirl is correlated to increased shear stress along the cladding surface and subsequent erosion of the CRUD layer. The CIPS condition of the core is concluded to be primarily controlled by lithium tetraborate precipitation, referred to as boron hideout, which occurs in regions experiencing subcooled nucleate boiling as soluble boron and lithium species reach their solubility limit within the CRUD layer. Subsequently, a localized reduction in power occurs due to the high neutron absorption cross section of boron-10

  9. Crud deposits on zircaloy-clad fuel

    International Nuclear Information System (INIS)

    Lister, D.H.

    1980-05-01

    The information on in-reactor corrosion of Zircaloy fuel cladding and crud deposition on fuel generated by Atomic Energy of Canada Limited up to 1979 has been reviewed elsewhere. This report is a summary of the crud deposition part of that review. (auth)

  10. Removing device for fuel assembly crud

    International Nuclear Information System (INIS)

    Ozaki, Shinji; Kanehira, Yoshinori; Iwai, Takashi.

    1993-01-01

    The device of the present invention removes cruds deposited on the surface of fuel assemblies in fuel pool water efficiently, to prevent leakage of cruds into the pool water. That is, a fuel cleaning vessel is disposed in the fuel pool water. Cruds on the surface of the fuel assembly are removed by a ultrasonic wave oscillator while the fuel assembly moves vertically in the cleaning vessel. Removed cruds are sucked together with water in the cleaning vessel by a submerged pump, and sent to a preceding coarse filter, in which relatively great cruds are captured. Fine cruds passing through the preceding filter are sent to a succeeding fine filter together with the filtered water by way of a water supply pump at the outside of the pool, in which fine cruds are completely captured. The filtered water is released into the pool water again. Since the two stage filters are prepared, each of the filters is less clogged. Accordingly, frequency for the exchange of the filters can be reduced. (I.S.)

  11. Reprocessing cruds: zirconium (IV) contribution to their formation dibutylphosphoric acid demixion induced by zirconium (IV) in nitric acid solutions. Solubility of zirconium (IV) in HDBP

    International Nuclear Information System (INIS)

    Livet, J.; Berthon, C.

    1994-01-01

    The low Zr(IV) compounds solubility with the most important degradation products of tributylphosphate (TBP), the PUREX process extractant (dibutylphosphoric acid (HDBP) and monobutylphosphoric acid (H 2 MBP)), can strongly disturb the implementation of the process (clogging or third phases formation). CEA studied systematically the formation and the properties of these compounds: 31 P nuclear magnetic resonance spectroscopy allowed to understand the original Zr(IV) property that induces demixions of HDBP from aqueous nitric solutions. The temperature variation and the spectra simulation induce that Zr(IV) is very soluble in pure HDBP (more than 1M). Zr(IV) in HDBP solutions can also be prepared by dissolving Zr(DBP) 2 (NO 3 ) 2 in HDBP. 4 figs., 4 refs

  12. Reprocessing cruds: zirconium (IV) contribution to their formation dibutylphosphoric acid demixion induced by zirconium (IV) in nitric acid solutions. Solubility of zirconium (IV) in HDBP

    Energy Technology Data Exchange (ETDEWEB)

    Livet, J.; Berthon, C.

    1994-12-31

    The low Zr(IV) compounds solubility with the most important degradation products of tributylphosphate (TBP), the PUREX process extractant (dibutylphosphoric acid (HDBP) and monobutylphosphoric acid (H{sub 2}MBP)), can strongly disturb the implementation of the process (clogging or third phases formation). CEA studied systematically the formation and the properties of these compounds: {sup 31}P nuclear magnetic resonance spectroscopy allowed to understand the original Zr(IV) property that induces demixions of HDBP from aqueous nitric solutions. The temperature variation and the spectra simulation induce that Zr(IV) is very soluble in pure HDBP (more than 1M). Zr(IV) in HDBP solutions can also be prepared by dissolving Zr(DBP){sub 2}(NO{sub 3}){sub 2} in HDBP. 4 figs., 4 refs.

  13. Understanding Alliance Formation Patterns

    Science.gov (United States)

    2015-12-01

    might take a different trend in different eras, in which it is either positive, leading to a bigger chance of alliance formation , or negative, leading...of war and peace with regard to systemic analysis. Therefore, it is reasonable that there is a deviation in the trends of alliance formation during...ALLIANCE FORMATION PATTERNS by Wael Abbas Zoltan Schneider December 2015 Thesis Advisor: William P. Fox Second Reader: Heather S. Gregg

  14. Mechanism of crud migration into the fuelling machine and its effects

    International Nuclear Information System (INIS)

    Sie, T.

    2003-01-01

    'Full text:' The objective of this paper is to summarize the opinion of experts on the mechanism of crud deposit formation and its migration into the fueling machine. Also to point out the negative effects of crud on the performance of the fueling machine head and the head overhaul / maintenance program in general. There are numerous moving/rotating components (ball screws, linear and rotating bearings, mechanical gears, mechanical seals, etc.) inside the fueling machine. By design, all these are lubricated by D2O. Because of the delicate nature of the moving components, crud contaminated D2O is obviously not a good choice of lubricant. Crud causes poor performance of the FM drive systems, premature wear of the mechanical seals, and other internal components. Due to the fuelling machine's role in maintaining reactor power and safety related functions, it is of extreme importance that the performance of the fueling machine is controlled. Major field functional failures must be prevented. In the extreme case the effect of the crud contaminated D2O could lead to a major functional failure while the fueling machine is locked on channel or has irradiated fuel on board. The next worse scenario is intolerably frequent process stops, thus requiring costly and premature fuelling machine overhaul / repairs with its associated negative effects: maintenance cost, radiation exposure, reduced fueling rates, and major upsets to the general head overhaul schedule. (author)

  15. The fractalline properties of experimentally simulated PWR fuel crud

    Science.gov (United States)

    Dumnernchanvanit, I.; Mishra, V. K.; Zhang, N. Q.; Robertson, S.; Delmore, A.; Mota, G.; Hussey, D.; Wang, G.; Byers, W. A.; Short, M. P.

    2018-02-01

    The buildup of fouling deposits on nuclear fuel rods, known as crud, continues to challenge the worldwide fleet of light water reactors (LWRs). Crud may cause serious operational problems for LWRs, including axial power shifts, accelerated fuel clad corrosion, increased primary circuit radiation dose rates, and in some instances has led directly to fuel failure. Numerous studies continue to attempt to model and predict the effects of crud, but each makes critical assumptions regarding how to treat the complex, porous microstructure of crud and its resultant effects on temperature, pressure, and crud chemistry. In this study, we demonstrate that crud is indeed a fractalline porous medium using flowing loop experiments, validating the most recent models of its effects on LWR fuel cladding. This crud is shown to match that in other LWR-prototypical facilities through a porosity-fractal dimension scaling law. Implications of this result range from post-mortem analysis of the effects of crud on reactor fuel performance, to utilizing crud's fractalline dimensions to quantify the effectiveness of anti-fouling measures.

  16. Crud in the solvent extraction process for spent fuel reprocessing

    International Nuclear Information System (INIS)

    Chen Jing

    2004-01-01

    The crud occurred in Purex process is caused by the degradations of extractant and solvent and the existence of insoluble solid particle in the nuclear fuel reprocessing. The crud seriously affects the operation of the extraction column. The present paper reviews the study status on the crud in the Purex process. It is generally accepted that in the Purex process, particularly in the first cycle, the crud occurrence is related to the capillary chemistry phenomena resulting from the deposits of Zr with TBP degradation products HDBP, H 2 MBP, H 3 PO 4 and the insoluble particle RuO 2 and Pd. The occurrence of deposits and the type of crud are tightly related to the molar ratio of HDBP and Zr, and the aqueous pH. In addition, the effect of degradation products from the diluent, such as kerosene, is an unnegligible factor to cause the crud. The crud can be discharged from the extraction equipment with Na 2 CO 3 or oxalic acid. In the study on simulating the crud, the effects of the deposits of Zr with TBP degradation products HDBP, H 2 MBP and H 2 PO 4 , and the insoluble particle RuO 2 and Pd should be considered at the same time. (authors)

  17. On-line, in-core measurement of the thermal conductivity of a BWR fuel rod with a tenacious crud deposit

    International Nuclear Information System (INIS)

    Bennett, Peter

    2012-09-01

    Several corrosion-related fuel failures in US BWRs have been reported where the failed rods had thick, tenacious crud deposits, including events at River Bend and Browns Ferry. Although investigations did not identify the root cause of these failures, it was noted that there was an industry perception that the level of crud on the fuel in a number of plants - including Browns Ferry - particularly those using NMCA, zinc and moderate to high Fe, was too high from a fuel performance perspective. The exact role of the crud was unknown, but there was a suspicion that some unknown water chemistry condition was responsible for the failures at Browns Ferry. Fuel failures have also occurred in Limerick-1, Cycle 2 and in Vermont Yankee, although the direct role of crud in these cases was not clear. While laboratory measurements have shown that the thermal conductivities of the species comprising the crud are not lower than that of ZrO 2 , the effect of the crud in impeding heat transfer has been implicated in the failure mechanisms. It is believed that steam blanketing (formation of a layer of steam between the rod surface and the crud) may be the cause of failure. Hence, to determine whether crud deposits impede heat transfer and thus cause or contribute to rod failure, it is necessary to measure their thermal conductivity during power operation under representative thermal-hydraulic and water chemistry conditions. The purpose of this test, conducted in the Halden Reactor, was to measure the heat transfer through BWR crud at power. Two test rods were manufactured from segments of a fuel rod irradiated in a commercial BWR to a burn-up of 41 GWd/MTU; one test rod had a thin crud layer (< 5 μm) while the other had a thick layer (> 25 μm). The rods were irradiated under representative thermal-hydraulic and water chemistry conditions (25 kW/m, 275 deg. C, outlet void fraction 4 per cent, 300 - 400 ppb H 2 ). Each rod was instrumented with a cladding elongation detector, and

  18. A review of crud mitigation and management strategy

    International Nuclear Information System (INIS)

    Choi, Joon Hyung; Lee, Jin Seok; Suh, Jung Min; Kim, Jae Won; Kim, Young Koo

    2004-01-01

    In Korea Nuclear Fuel Co.(KNFC), the database of domestic fuel failures has been developed and the study to find the causes of the fuel failures has been performed. With a severe operating conditions and aged reactor coolant system, crud induced localized corrosion (CILC) has been one of the causes of the fuel failures. Since 1991, all 14 fuel failures related to the crud and corrosion has been reported in US PWR plants. Even though no fuel failures by crud and corrosion have occurred in Korean plants, the possibilities of fuel failure by CILC have increased because of higher burnup, longer cycle and power uprating program. In this study, international trend for the crud mitigation and management strategy will be reviewed to establish an integrated program that is to be used in KNFC

  19. Characterization of molybdenum interfacial crud in a uranium mill that employs tertiary-amine solvent extraction

    International Nuclear Information System (INIS)

    Moyer, B.; McDowell, W.J.

    1983-01-01

    In the present work, samples of a molybdenum-caused green gummy interfacial crud from an operating western US uranium mill have been physically and chemically examined. Formaton of cruds of this description has been a long-standing problem in the use of tertiary amine solvent extraction for the recovery of uranium from low-grade ores (Amex Process). The crud is essentially an organic-continuous dispersion containing about 10 wt % aqueous droplets and about 37 wt % greenish-yellow crystalline solids suspended in kerosene-amine process solvent. The greenish-yellow crystals were found to be a previously unknown double salt of tertiary amine molybdophosphate with three tertiary amine chlorides having the empirical formula (R 3 NH) 3 [PMo 12 O 40 ].3(R 3 NH)Cl. To confirm the identification of the compound, a pure trioctylamine (TOA) analog was synthesized. In laboratory extraction experiments, it was demonstrated that organic-soluble amine molydophosphate forms slowly upon contact of TOA solvent with dilute sulfuric acid solutions containing low concentrations of molybdate and phosphate. If the organic solutions of amine molybdophosphate were then contacted with aqueous NaCl solutions, a greenish-yellow precipitate of (TOAH) 3 [PMo 12 O 40 ].3(TOAH)Cl formed at the interface. The proposed mechanism for the formation of the crud under process conditions involves build up of molybdenum in the solvent, followed by reaction with extracted phosphate to give dissolved amine molybdophosphate. The amine molybdophosphate then co-crystallizes with amine chloride, formed during the stripping cycle, to give the insoluble double salt, which precipitates as a layer of small particles at the interface. The proposed solution to the problem is the use of branched-chain, instead of straight-chain, tertiary amine extractants under the expectation that branching would increase the solubility of the double salt. 2 figures, 5 tables

  20. A study of solute transport of radiolysis products in crud and its effects on crud growth on PWR fuel pin

    International Nuclear Information System (INIS)

    Joe, Justin H.; Kim, Seung Jun; Jones, Barclay G.

    2016-01-01

    Highlights: • We model a 3-D numerical solute transport within crud deposit on PWR fuel pin. • Source term effect from radiolysis yield and recombination is minimal. • Lower crud porosity leads substantially higher concentration of solutes. • Thicker crud deposit generates substantially higher concentration of solutes. • High concentration of radiolysis species (H 2 , O 2 , and H 2 O 2 ) can be directly related to corrosion issues on fuel cladding. - Abstract: This research examines the concentration of radiolysis species (H 2 , O 2 , and H 2 O 2 ) over the porous crud layer using a three dimensional time dependent solute transport model. A Monte Carlo random walk technique is adopted to simulate the transport behavior of the different species with various parametric studies of source term, crud thickness, and crud porosity. Particularly, this model employs a system of coupled mass transport and chemical interactions as the source term, which makes the problem non-linear. It is demonstrated that a negligible effect on radiolysis species concentrations change due to the consideration of source term. The crud thickness and porosity effect on the concentration distributions are notably observed. In general, higher concentration starts from the intersection of the heating surface with the chimney wall from the beginning and it reaches the equilibrium state within tens of seconds. The concentration profiles of the radiolysis species H 2 , O 2 , and H 2 O 2 can be directly related to corrosion issues. The direct application of this study to nuclear engineering research is to aid in the design of reactors with higher performance without experiencing an Axial Offset Anomaly (AOA), an unexpected measured shift in axial power distribution from predicted values.

  1. Atomic scale simulations for improved CRUD and fuel performance modeling

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Anders David Ragnar [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cooper, Michael William Donald [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-06

    A more mechanistic description of fuel performance codes can be achieved by deriving models and parameters from atomistic scale simulations rather than fitting models empirically to experimental data. The same argument applies to modeling deposition of corrosion products on fuel rods (CRUD). Here are some results from publications in 2016 carried out using the CASL allocation at LANL.

  2. Investigation of CRUD interphasic products resulting from nuclear technology operations

    International Nuclear Information System (INIS)

    Humelnicu, Doina; Cecal, Al.

    2002-01-01

    This paper presents some aspects of the study of CRUD products. These products occur at the interface of aqueous phase/organic phase during the extraction processes of uranium with organic non-miscible solvents. Some methods of destroying these products, especially by acid treatments were proposed. By these treatments, interphase products have been destroyed and, in time, they did not occurred anymore. (author)

  3. College Students' Understanding of Atmospheric Ozone Formation

    Science.gov (United States)

    Howard, Kristen E.; Brown, Shane A.; Chung, Serena H.; Jobson, B. Thomas; VanReken, Timothy M.

    2013-01-01

    Research has shown that high school and college students have a lack of conceptual understanding of global warming, ozone, and the greenhouse effect. Most research in this area used survey methodologies and did not include concepts of atmospheric chemistry and ozone formation. This study investigates college students' understandings of atmospheric…

  4. Results of a recent crud/corrosion fuel risk assessment at a U.S. PWR

    International Nuclear Information System (INIS)

    Lamanna, Larry; Pop, Mike; Gregorich, Carola; Harne, Richard; Jones, John

    2012-09-01

    In order to avoid potential fuel reliability issues, specifically crud-related issues, it is necessary to achieve and maintain a crud safe environment. Therefore, the ability to confidently predict risks associated with crud deposition on fuel becomes critically important. AREVA is applying its cutting-edge PWR Fuel Crud (Primary System corrosion products)/Corrosion Tools, i.e. COBRA-FLX (subchannel-by-subchannel T/H tool) coupled with FDIC (crud deposition tool) to subsequently perform PWR Fuel Crud /Corrosion risk assessments for operating plants in the US. After describing the method, the result of one of these assessments is presented for an operating plant in the US that has experienced recent crud observations/concerns. Both Crud Induced Localized Corrosion (CILC) and Crud Induced Power Shift (CIPS) risk assessment methods, as applied to the upcoming cycle (Cycle N), were compared to the current/on-going cycle (Cycle N-1) and to the previous cycle (Cycle N-2). The results allowed the Utility to consider crud risk management changes associated with the upcoming cycle (Cycle-N). Benchmarking of the AREVA tools, using the plant-specific crud information gained from the crud sampling/characterization for the Unit will be presented. The CIPS analysis references boron loading and the amount of insoluble iron-nickel-borates predicted for Cycles N-2, N-1, and N. The results of the CILC evaluation reference FDIC-predicted crud thickness, cladding temperature under deposit, evolution of CILC bearing species and lithium concentration in the zirconium oxide layer. The approach taken by AREVA during the evaluation was to consider both 'risk' and 'margin' to fuel performance impact caused by crud deposits. The conclusion of the assessment, illustrated by the results presented in this paper, is that the example Plant has sufficient margin in worst case conditions for CIPS and CILC risk in Cycle N, based on Cycle N-1 and Cycle N-2 conditions and behavior

  5. Initial experimental evaluation of crud-resistant materials for light water reactors

    Science.gov (United States)

    Dumnernchanvanit, I.; Zhang, N. Q.; Robertson, S.; Delmore, A.; Carlson, M. B.; Hussey, D.; Short, M. P.

    2018-01-01

    The buildup of fouling deposits on nuclear fuel rods, known as crud, continues to challenge the worldwide fleet of light water reactors (LWRs). Crud causes serious operational problems for LWRs, including axial power shifts, accelerated fuel clad corrosion, increased primary circuit radiation dose rates, and in some instances has led directly to fuel failure. Numerous studies continue to attempt to model and predict the effects of crud, but each assumes that it will always be present. In this study, we report on the development of crud-resistant materials as fuel cladding coatings, to reduce or eliminate these problems altogether. Integrated loop testing experiments at flowing LWR conditions show significantly reduced crud adhesion and surface crud coverage, respectively, for TiC and ZrN coatings compared to ZrO2. The loop testing results roughly agree with the London dispersion component of van der Waals force predictions, suggesting that they contribute most significantly to the adhesion of crud to fuel cladding in out-of-pile conditions. These results motivate a new look at ways of reducing crud, thus avoiding many expensive LWR operational issues.

  6. Method of removing crud deposited on fuel element clusters

    International Nuclear Information System (INIS)

    Yokota, Tokunobu; Yashima, Akira; Tajima, Jun-ichiro.

    1982-01-01

    Purpose: To enable easy elimination of claddings deposited on the surface of fuel element. Method: An operator manipulates a pole from above a platform, engages the longitudinal flange of the cover to the opening at the upper end of a channel box and starts up a suction pump. The suction amount of the pump is set such that water flow becomes within the channel box at greater flow rate than the operational flow rate in the channel box of the fuel element clusters during reactor operation. This enables to remove crud deposited on the surface of individual fuel elements with ease and rapidly without detaching the channel box. (Moriyama, K.)

  7. Modeling and Thermal Performance Evaluation of Porous Curd Layers in Sub-Cooled Boiling Region of PWRs and Effects of Sub-Cooled Nucleate Boiling on Anomalous Porous Crud Deposition on Fuel Pin Surfaces

    International Nuclear Information System (INIS)

    Barclay Jones

    2005-01-01

    A significant number of current PWRs around the world are experiencing anomalous crud deposition in the sub-cooled region of the core, resulting in an axial power shift or Axial Offset Anomaly (AOA), a condition that continues to elude prediction of occurrence and thermal/neutronic performance. This creates an operational difficulty of not being able to accurately determine power safety margin. In some cases this condition has required power ''down rating'' by as much as thirty percent and the concomitant considerable loss of revenue for the utility. This study examines two aspects of the issue: thermal performance of crud layer and effect of sub-cooled nucleate boiling on the solute concentration and its influence on initiation of crud deposition/formation on fuel pin surface

  8. Integrated Electronic Microscopy Method to Characterize BWR Crud Deposits

    International Nuclear Information System (INIS)

    Pop, Mike G.; Lockamon, Brian; Howe, James M.; Oleshko, Vladimir P.

    2007-01-01

    The primary objective of this paper is to present the best combination of analytical Electron Microscopy (EM) techniques suited for studying Boiling Water Reactor (BWR) fuel crud deposits in their 'as found' condition, for example un-adulterated portions of the deposits located in crevices at the surface of deposit. The secondary objective of the paper is to suggest a strategy to connect the analytical EM results with the Power Diffraction File (PDF-4) crystal database to ultimately explain crystal growth phenomena in crevices. The samples analyzed as part of this work were collected from steam generators in Nuclear Power Plants. These samples were selected as segregates for BWR deposits due to their similar structures and because they were freely releasable for study in the University labs. The samples were analyzed extensively through various EM techniques at magnifications up to 150,000 X. Subsequent evaluation of the analysis results demonstrated that the selected samples exhibited characteristics that were very close to second-burned fuel crud deposits from operating BWR plants. (authors)

  9. Characteristics of fuel crud and its impact on storage, handling, and shipment of spent fuel

    International Nuclear Information System (INIS)

    Hazelton, R.F.

    1987-09-01

    Corrosion products, called ''crud,'' form on out-of-reactor surfaces of nuclear reactor systems and are transported by reactor coolant to the core, where they deposit on external fuel-rod cladding surfaces and are activated by nuclear reactions. After discharge of spent fuel from a reactor, spallation of radioactive crud from the fuel rods could impact wet or dry storage operations, handling (including rod consolidation), and shipping. It is the purpose of this report to review earlier (1970s) and more recent (1980s) literature relating to crud, its characteristics, and any impact it has had on actual operations. Crud characteristics vary from reactor type to reactor type, reactor to reactor, fuel assembly to fuel assembly in a reactor, circumferentially and axially in an assembly, and from cycle to cycle for a specific facility. To characterize crud of pressurized-water (PWRs) and boiling-water reactors (BWRs), published information was reviewed on appearance, chemical composition, areal density and thickness, structure, adhesive strength, particle size, and radioactivity. Information was also collected on experience with crud during spent fuel wet storage, rod consolidation, transportation, and dry storage. From experience with wet storage, rod consolidation, transportation, and dry storage, it appears crud spallation can be managed effectively, posing no significant radiological problems. 44 refs., 11 figs

  10. Investigation of various crud particles originated from NPP Paks, Hungary

    Energy Technology Data Exchange (ETDEWEB)

    Csordas, Anna Pinter; Vajda, Nora; Kerkapoly, Aniko (and others)

    2005-07-01

    Morphology, elemental composition and radioactivity of solid particles - aggregates of crud originated from NPP Paks were studied by micro- and radioanalytical methods. Solid particles were taken: 1) from the primary coolant during transient operational conditions (reactor shutdown); 2) from the coolant contaminated by fuel debris due to the incident happened at the cleaning tank in April 2003; 3) particles collected from the fuel element surfaces and 4) from some steam generator tubes. Crud particles - aggregates from the primary coolant and from the incidentally contaminated water were studied by autoradiography, SEM - EDX and by alpha spectrometry. Based on the measured transuranium ratios, the burn up of these particles was estimated. Examination of particles originated from the incidentally damaged fuel has shown that particles with high burn up originated from the 'rim' layer were released, too. Application of SEM -EDX methods on corrosion particles taken from the primary coolant and from some steam generator tubes makes it possible to compare them and to find the possible origin of the corrosion particles in the primary coolant - the cleaning of the steam generator tubes performed earlier. By determination of the specific activities of long-lived corrosion products using beta and gamma spectrometry and ICP-MS technique, the residence times of them were estimated. According to these data, the studied particles could be grouped into two classes: 1) particles residing in the zone for longer period and taken by the primary coolant; 2) particles activated in the zone only for shorter period and then deposited on the steam generator tubes. (Author)

  11. Experiences of ultra-low-crud high-nickel control in Onagawa nuclear power station

    International Nuclear Information System (INIS)

    Saito, M.; Goto, Y.; Shinomiya, T.; Sato, M.; Yamazaki, K.; Hirasawa, H.; Yotsuyanagi, T.

    2002-01-01

    We have adopted various countermeasures for worker dose reduction to plants in Onagawa Nuclear Power Station. ''Ni/Fe ratio control'' has been adopted to Unit 1, and ''ultra-low-crud high-nickel control'' has been adopted to Unit 2 and 3, along with other countermeasures like wide utilization of low Co materials, for the purpose of dose rate reduction of primary recirculation piping which is thought to be one of the main exposure sources. In this paper, we describe, first, the reason and background that ultra-low-crud high-nickel control has been adopted to Unit 2, and, second, water chemistry of Unit 2 up to the 5. cycle under ultra-low-crud high-nickel control compared to that of Unit 1 under Ni/Fe ratio control. Following those, we show brief analysis of the fuel crud of Unit 2 and water chemistry of Unit 3 only at the startup stage. (authors)

  12. A comparison of crud phases appearing on some Swedish BWR fuel rods using Laser Raman Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hermansson, H.P. [Studsvik Nuclear AB, Nykoeping (Sweden)]|[Lulea Univ. of Technology (Sweden)

    2002-07-01

    Previous investigations showed that laser Raman spectroscopy (LRS) can be used as a phase specific analytical tool for radioactive fuel crud samples and also for details in the underlying layer of zirconium dioxide. It is relatively easy to record Raman spectra that discriminate between chemical phases for all crud oxides of interest. The method has therefore been recommended for crud investigations within the Swedish program. At ideal conditions the resolution is about 1 {mu}m, permitting detailed position determination of crud phases in the sample. Therefore LRS is a very good complement to X-ray diffraction (XRD). The methods for sample preparation and handling of radioactive crud samples for LRS turn out to be relatively simple. A detailed LRS study on fuel crud samples from Barsebaeck 2, Forsmark 2, Forsmark 3 and Ringhals 1 was performed in this work. All of those Swedish BWRs were operated at different conditions at the time of sampling. The chemistry regimes covered NWC, HWC and other variable conditions. Also different types of fuel, exposure times and sampling positions were selected. (authors)

  13. Understanding coupling between bone resorption and formation

    DEFF Research Database (Denmark)

    Andersen, Thomas Levin; Abdelgawad, Mohamed Essameldim; Kristensen, Helene Bjørg

    2013-01-01

    Bone remodeling requires bone resorption by osteoclasts, bone formation by osteoblasts, and a poorly investigated reversal phase coupling resorption to formation. Likely players of the reversal phase are the cells recruited into the lacunae vacated by the osteoclasts and presumably preparing...... these lacunae for bone formation. These cells, called herein reversal cells, cover >80% of the eroded surfaces, but their nature is not identified, and it is not known whether malfunction of these cells may contribute to bone loss in diseases such as postmenopausal osteoporosis. Herein, we combined...... physiological status. Their prevalence correlated with decreased trabecular bone volume and osteoid and osteoblast surfaces in postmenopausal osteoporosis. They were, however, virtually absent in primary hyperparathyroidism, in which the transition between bone resorption and formation occurs optimally...

  14. Modelling of CRUD growth phenomena on PWR fuel rods under nucleate boiling conditions

    International Nuclear Information System (INIS)

    Ferrer, A.; Dacquait, F.; Gall, B.; Ranchoux, G.; Riot, G.

    2012-09-01

    PWR primary circuit materials undergo general corrosion leading to a release of metallic element release and subsequent process of particle deposition and ion precipitation on the primary circuit surfaces. The species accumulated on fuel rods are activated by neutron flux. Consequently, crud erosion and dissolution induce primary coolant contamination. In French PWRs, 58 Co volume activity is generally low and almost constant (< 30 MBq.m -3 ) throughout an ordinary operating cycle. In some specific cases, a significant increase in volume activity is observed after the middle of a cycle (100-1000 MBq.m -3 for 58 Co) when conditions for nucleate boiling are locally reached in certain fuel assemblies. Indeed, it is well known that nucleate boiling intensifies the deposition process. The thickness of the crud layer can reach some micrometers in non-boiling areas, whereas it can reach 100 micrometers in boiling areas. Crud growth in boiling conditions can be related to three phenomena: bubble growth induces deposition process (called boiling deposition), bubbles induce concentration increase at crud-coolant interface (called enrichment and modelled by the enrichment factor, the ratio between the wall concentration and the bulk concentration) and vaporisation induces concentration increase inside the crud. A literature review on the modelling of these phenomena and on the crud structure in nucleate boiling conditions has been carried out. The OSCAR [1] calculation code developed by the CEA to predict surface and volume activities in a single phase PWR primary circuit was chosen as a basis for present study. Ability to describe local nucleate boiling conditions was added to this code leading to realistic modelling of subsequent volume activity increase. In this article, we present the results obtained using a modified version of the OSCAR PC V1.2 calculation code including: - A double phase thermal-hydraulic module, - A model of boiling crud growth, able to calculate

  15. Corrosion behaviour and deposition of crud on Zr-alloys

    International Nuclear Information System (INIS)

    Maroto, A.J.G.; Bordoni, R.; Olmedo, A.M.; Villegas, M.; Chocron, M.; Szpunar, J.

    1999-01-01

    The results from the long term corrosion surveillance of Zr-alloys samples located out of pile in the primary heat transfer system of a PHWR with standard water chemistry show that, up to 3400 days, the mean value of the oxide thickness obtained for Zr-2.5Nb and Zry-4 samples exposed at 305 deg. C is in good agreement with the values reported in the literature. The amount of crud deposited on the corrosion samples was calculated at every inspection of the long term surveillance programme. The corrosion behaviour of these alloys is also studied in static autoclaves with lithiated heavy water. The effect on Zr-alloys of a change in chemistry resulting from the degradation of mixed resins in the primary heat transfer system was investigated in additional tests in static autoclaves up to 120 days at 400 deg. C comparing the results with those from the corrosion samples inserted in the autoclave facilities of the plant. (author)

  16. Investigation on Hydrodynamic Cavitation of a Restriction Orifice and Static Mixer on Crud-like Deposits

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong Man; Lee, Seung Won; Park, Seong Dae; Kang, Sa Rah; Seo, Han; Bang, In Cheol [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2012-05-15

    Axial Offset Anomaly (AOA) referring to an unexpected neutron flux depression is also known as Crud Induced Power Shift (CIPS). Fuel assemblies removed from an AOA core have shown a thick porous deposition layer of crud on fuel clad surface. The deposition layer was induced by precipitation reactions of both boron species and crud during sub-cooled nucleate boiling. Therefore, to resolve the AOA issues, a fuel cleaning technology using ultrasonic cavitation has been developed by EPRI and applied to the domestic NPPs by KNF. However, the performance of crud removal during maintenance of NPPs is known to be not enough. Hydrodynamic cavitation is the process of vaporization, bubble generation and bubble implosion which occurs in a flowing liquid as a result of decrease and subsequent increase in pressure. Hydrodynamic cavitation generates shock pressure of a few tens MPa due to bubble collapse like the cavitation generated by Ultrasonics. It is well known that the cavitation can erode the metal surface. The idea of the current study is that such energetic cavitation bubble collapses could help to remove the crud from the fuel assembly. Therefore, the current study first investigates effects of hydrodynamic cavitation occurred from a single hole orifice and static mixer fundamentally

  17. Kinetics of filtration of model crud with ion exchange resin bed

    International Nuclear Information System (INIS)

    Takahashi, M.; Ishigure, K.; Fujita, N.

    1987-01-01

    A simple mathematical model is presented to depict the filtration mechanism of crud or colloidal particles in the ion exchange resin bed. In this model the filtration process is classified into four stages, corresponding to the increase in the deposited amounts of the particles on the surfaces of the resins during the filtration process. In the first stage, it is assumed that the adhesion of crud particles is mainly controlled by the electrokinetic interaction between the particle and the virgin surfaces of the resins, while in the third stage the crud particles interact with the particles already adsorbed in the resins. The second stage is a transient period between the first and third stages. In the final stage, the clogging effect becomes significant. At the first stage of filtration, the model explains the rapid decrease of filtration efficiency, which is a matter of great concern from the practical point of view. A comparison is made between the model and laboratory experiments, using monodispersed α-Fe/sub 2/O/sub 3/ particles as model crud, and it is found that the proposed mechanism of filtration process seems quite reasonable

  18. Experiences of ultra-low-crud high-nickel control in Onagawa nuclear power station

    Energy Technology Data Exchange (ETDEWEB)

    Saito, M.; Goto, Y.; Shinomiya, T.; Sato, M. [Tohoku Electric Power Co., Inc. (Japan); Yamazaki, K.; Hirasawa, H.; Yotsuyanagi, T. [Toshiba Corp. (Japan)

    2002-07-01

    We have adopted various countermeasures for worker dose reduction to plants in Onagawa Nuclear Power Station. ''Ni/Fe ratio control'' has been adopted to Unit 1, and ''ultra-low-crud high-nickel control'' has been adopted to Unit 2 and 3, along with other countermeasures like wide utilization of low Co materials, for the purpose of dose rate reduction of primary recirculation piping which is thought to be one of the main exposure sources. In this paper, we describe, first, the reason and background that ultra-low-crud high-nickel control has been adopted to Unit 2, and, second, water chemistry of Unit 2 up to the 5. cycle under ultra-low-crud high-nickel control compared to that of Unit 1 under Ni/Fe ratio control. Following those, we show brief analysis of the fuel crud of Unit 2 and water chemistry of Unit 3 only at the startup stage. (authors)

  19. Primary side crud sampling and characterization: how it may help to better maintain CANDU reactors

    Energy Technology Data Exchange (ETDEWEB)

    Sawicki, J.A.; Dymarski, M.; Sawicka, B.D. [Atomic Energy of Canada Limited, Chalk River, ON (Canada)

    1997-07-01

    The paper reports a corrosion-product transport study in the primary-side of CANDU reactors. The study is based on systematic crud sampling examinations at Darlington NGS. Emphasis is placed on the corrosion-product transport and oxidation state as a monitor of primary water chemistry state, and as a monitor of system corrosion effects. The D{sub 2}O was sampled at reactor outlet headers and the deposits collected on 0.45 {mu}m membrane filters were analyzed by using {gamma}-ray spectroscopy, X-ray fluorescence and Moessbauer effect techniques. In the beginning of this study in 1994 and 1995, the steady state crude concentration used to be as high as 20 to 30 {mu}g/kg D{sub 2}O and the crud contained large fractions of highly oxidized species (40 to 60% Fe), in the form of ferrihydrite, lepidocrocite, goethite and hematite. During start-up operations, the crud concentrations were as high as 8 mg/kg D{sub 2}O and contained 70 to 80% Fe in the form of oxidized iron species. However, as a result of various improvements, and especially because of better oxygen control during lay-ups (nitrogen blanketing) and better pH control (lower and more stable values), in recent steady-state runs, the crud concentrations were found to be lower than 3 to 5 {mu}g/kg D{sub 2}O. At present, the steady-state crud consists mostly of Fe, largely in the form of magnetite (60 to 80% Fe), and hematite (20 to 40% Fe). The steady-state concentration of crud was found to increase markedly with pH{sub a} in the range from 10.3 to 10.7. This seems to be in accord with the trend predicted by flow-assisted solubility of magnetite in lithiated water at {approx} 300 degrees C, and is generally in accord with the model of dissolution, transport, and redeposition of iron in the primary heat transport system of CANDU reactors. The crud contains also significant amounts of Zr ({approx} 5 to 30 wt. % Fe), apparently in the form of zirconium oxide. Zirconium oxide particles may originate largely from the

  20. Understanding the star formation modes in the distant universe

    International Nuclear Information System (INIS)

    Salmi, Fadia

    2012-01-01

    The goal of my PhD study consists at attempt to understand what are the main processes at the origin of the star formation in the galaxies over the last 10 billion years. While it was proposed in the past that merging of galaxies has a dominant role to explain the triggering of the star formation in the distant galaxies having high star formation rates, in the opposite, more recent studies revealed scaling laws linking the star formation rate in the galaxies to their stellar mass or their gas mass. The small dispersion of these laws seems to be in contradiction with the idea of powerful stochastic events due to interactions, but rather in agreement with the new vision of galaxy history where the latter are continuously fed by intergalactic gas. We were especially interested in one of this scaling law, the relation between the star formation (SFR) and the stellar mass (M*) of galaxies, commonly called the main sequence of star forming galaxies. We studied this main sequence, SFR-M * , in function of the morphology and other physical parameters like the radius, the colour, the clumpiness. The goal was to understand the origin of the sequence's dispersion related to the physical processes underlying this sequence in order to identify the main mode of star formation controlling this sequence. This work needed a multi-wavelength approach as well as the use of galaxies profile simulation to distinguish between the different galaxy morphological types implied in the main sequence. (author) [fr

  1. Technical description of the NRC long-term whole-rod and crud performance test

    International Nuclear Information System (INIS)

    Einziger, R.E.; Fish, R.L.; Knecht, R.L.

    1982-09-01

    Westinghouse Hanford Company (WHC) and EG and G-Idaho are jointly conducting a long-term, low-temperature, spent-fuel, whole rod and crud behavior test to provide the Nuclear Regulatory Commission (NRC) with information to assist in the licensing of light water reactor (LWR) spent-fuel, dry storage facilities. Readily available fuel rods from an H.B. Robinson Unit 2 (PWR) fuel assembly and a Peach Bottom-II (BWR) fuel assembly were selected for use in the 50-month test. Both intact and defected rods will be tested in inert and oxidizing atmospheres. A 230 0 C test temperature was selected for the first 10-month run. Both nondestructive and destructive examinations are planned to characterize the fuel rod behavior during the 5-y test. Four interim examinations and a final examination will be conducted. Crud spallation behavior will be investigated by sampling the crud particulate from the test capsules at each of the four interim examinations and at the end of the test. The background to whole rod testing, description of rod breach mechanisms, and a detailed description of the test are presented in this document

  2. Understanding the mechanism of nanoparticle formation in wire explosion process

    International Nuclear Information System (INIS)

    Bora, B.; Wong, C.S.; Bhuyan, H.; Lee, Y.S.; Yap, S.L.; Favre, M.

    2013-01-01

    The mechanism of nanoparticle formation by wire explosion process has been investigated by optical emission spectroscopy in Antony et al. 2010 [2] [J Quant Spectrosc Radiat Transfer 2010; 111:2509]. It was reported that the size of the nanoparticles formed in Ar ambience increases with increasing pressure, while an opposite trend was observed for the nanoparticles produced in N 2 and He ambiences. However, the physics behind this opposite trend seems unclear. In this work, we have investigated the probable mechanism behind the opposite trend in particle size with pressure of different gases and understand the mechanism of nanoparticle formation in wire explosion process. The experiment was carried out to investigate the effect of ambient gas species (Ar and N 2 ) and pressure on arc plasma formation and its corresponding effects on the characteristics of the produced nanoparticles in wire explosion process. Our results show that the arc plasma formation is probably the mechanism that may account for the opposite trend of particle size with pressure of different gases. -- Highlights: ► Cu nanoparticles have been synthesized by wire explosion technique. ► Investigate the effect of the ambient gas species and pressure. ► Arc plasma formation in wire explosion process is investigated. ► Arc plasma formation plays a crucial role in characteristic of the nanoparticles

  3. L3.PHI.CTF.P10.02-rev2 Coupling of Subchannel T/H (CTF) and CRUD Chemistry (MAMBA1D)

    Energy Technology Data Exchange (ETDEWEB)

    Salko, Robert K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Palmtag, Scott [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Collins, Benjamin S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kendrick, Brian [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Seker, Jeffrey [Westinghouse Electric Company LLC, Cranberry Township, PA (United States)

    2015-05-15

    The purpose of this milestone is to create a preliminary capability for modeling light water reactor (LWR) thermal-hydraulic (T/H) and CRUD growth using the CTF subchannel code and the subgrid version of the MAMBA CRUD chemistry code, MAMBA1D. In part, this is a follow-on to Milestone L3.PHI.VCS.P9.01, which is documented in Report CASL-U-2014-0188-000, titled "Development of CTF Capability for Modeling Reactor Operating Cycles with Crud Growth". As the title suggests, the previous milestone set up a framework for modeling reactor operation cycles with CTF. The framework also facilitated coupling to a CRUD chemistry capability for modeling CRUD growth throughout the reactor operating cycle. To demonstrate the capability, a simple CRUD \\surrogate" tool was developed and coupled to CTF; however, it was noted that CRUD growth predictions by the surrogate were not considered realistic. This milestone builds on L3.PHI.VCS.P9.01 by replacing this simple surrogate tool with the more advanced MAMBA1D CRUD chemistry code. Completing this task involves addressing unresolved tasks from Milestone L3.PHI.VCS.P9.01, setting up an interface to MAMBA1D, and extracting new T/H information from CTF that was not previously required in the simple surrogate tool. Speci c challenges encountered during this milestone include (1) treatment of the CRUD erosion model, which requires local turbulent kinetic energy (TKE) (a value that CTF does not calculate) and (2) treatment of the MAMBA1D CRUD chimney boiling model in the CTF rod heat transfer solution. To demonstrate this new T/H, CRUD modeling capability, two sets of simulations were performed: (1) an 18 month cycle simulation of a quarter symmetry model of Watts Bar and (2) a simulation of Assemblies G69 and G70 from Seabrook Cycle 5. The Watts Bar simulation is merely a demonstration of the capability. The simulation of the Seabrook cycle, which had experienced CRUD-related fuel rod failures, had actual CRUD-scrape data to compare with

  4. Product Evaluation Task Force Phase Two report for MEB crud/filter aid

    International Nuclear Information System (INIS)

    Francis, A.J.

    1991-01-01

    It has been proposed that all Intermediate Level Wastes arising at Sellafield should be encapsulated prior to ultimate disposal. The Product Evaluation Task Force (PETF) was set up to investigate possible encapsulants and to produce an adequate data base to justify the preferred matrices. This report details the work carried out, under Phase 2 of the Product Evaluation Task Force programme, on MEB Crud/Filter Aid. Three possible types of encapsulants for MEB Crud/Filter Aid:- Inorganic cements, Polymer cements, and Polymers are evaluated using the Kepner Tregoe decision and analysis technique. This technique provides a methodology for scoring and ranking alternative options and evaluating any risks associated with an option. The analysis shows that for all four stages of waste management operations, ie Storage, Transport, handling and emplacement, Disposal and, Process, cement matrices are considerably superior to other potential matrices. A matrix, consisting of nine parts Blast Furnace Slag (BFS) to one part Ordinary Portland Cement (OPC) is recommended as the preferred matrix for Phase 3 studies on MEB/Filter Aid. (author)

  5. Towards Understanding the Star Formation-Feedback Loop in Galaxy Formation and Evolution

    Science.gov (United States)

    Kravtsov, Andrey

    We propose to carry out a comprehensive study of how star formation and feedback loop influences evolution of galaxies using a suite of ultra-high resolution cosmological simulations of galaxy formation using the Adaptive Mesh Refinement (AMR) approach implemented in the Adaptive Refinement Tree (ART) code. The simulations will result in the numerical models of galaxy evolution of unprecedented resolution and sophistication of the processes included. Our code includes treatment of a wide spectrum of processes critical for realistic modeling of galaxy formation from the primordial chemistry of hydrogen and helium species, radiative transfer of ionizing radiation, to the metallicity- dependent cooling, chemistry of molecular hydrogen on dust and treatment of radiative transfer of dissociating far ultraviolet radiation. The latter allows us to tie star formation with dense, molecular regions capable of self-shielding from heating radiation and avoid adopting arbitrary density and temperature thresholds for star formation. Simulations will also employ a new model for momentum injection due to radiation pressure exerted by young massive stars onto surrounding dust and gas. This early, pre-supernova feedback is critical to prompt dispersal of natal molecular clouds and regulating star formation efficiency and increasing efficiency of energy release by supernovae. The simulations proposed in this project will therefore treat the most important process to understanding the efficiency of baryon conversion to stars - the star formation - in the way most closely resembling the actual star formation observed in galaxies and stellar feedback model that is firmly rooted in observational evidence on how feedback operates in real molecular clouds. The simulations we propose will provide models of galaxy evolution during three important epochs in the history of the universe: (1) early evolution prior to and during the reionization of the universe (the first billion years of

  6. Prediction of CRUD deposition on PWR fuel using a state-of-the-art CFD-based multi-physics computational tool

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, Victor [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, 2355 Bonisteel Boulv, Ann Arbor, MI (United States); Kendrick, Brian K. [Theoretical Division (T-1, MS B221), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Walter, Daniel [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, 2355 Bonisteel Boulv, Ann Arbor, MI (United States); Manera, Annalisa, E-mail: manera@umich.edu [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, 2355 Bonisteel Boulv, Ann Arbor, MI (United States); Secker, Jeffrey [Westinghouse Electric Company Nuclear Fuel Division, 1000 Westinghouse Drive, Cranberry Township, PA 16066 (United States)

    2016-04-01

    In the present paper we report about the first attempt to demonstrate and assess the ability of state-of-the-art high-fidelity computational tools to reproduce the complex patterns of CRUD deposits found on the surface of operating Pressurized Water Reactors (PWRs) fuel rods. A fuel assembly of the Seabrook Unit 1 PWR was selected as the test problem. During Seabrook Cycle 5, CRUD induced power shift (CIPS) and CRUD induced localized corrosion (CILC) failures were observed. Measurements of the clad oxide thickness on both failed and non-failed rods are available, together with visual observations and the results from CRUD scrapes of peripheral rods. Blind simulations were performed using the Computational Fluid Dynamics (CFD) code STAR-CCM+ coupled to an advanced chemistry code, MAMBA, developed at Los Alamos National Laboratory. The blind simulations were then compared to plant data, which were released after completion of the simulations.

  7. Understanding The Impact of Formative Assessment Strategies on First Year University Students’ Conceptual Understanding of Chemical Concepts

    OpenAIRE

    Mehmet Aydeniz; Aybuke Pabuccu

    2011-01-01

    This study investigated the effects of formative assessment strategies on students’ conceptual understanding in a freshmen college chemistry course in Turkey. Our sample consists of 96 students; 27 males, 69 females. The formative assessment strategies such as reflection on exams, and collective problem solving sessions were used throughout the course. Data were collected through pre and post-test methodology. The findings reveal that the formative assessment strategies used in this study led...

  8. Contribution of natural tracers for understanding transfers through argillaceous formations

    International Nuclear Information System (INIS)

    Bensenouci, F.

    2010-01-01

    This study is part of a research programme conducted by IRSN on the safety of deep geological disposal of high level and intermediate long-lived radioactive wastes. It more especially concerns the geological medium considered as a full component of the multi-barrier concept proposed by Andra for a deep repository. Indeed, the Callovo-Oxfordian argillite of the Paris Basin, in the east of France, is being investigated by Andra as a potential host rock for this repository. Performance assessment of this natural barrier is based on the knowledge of its confinement properties and therefore on phenomena possibly involved in the mass transport of radionuclides. In this context, this work aimed at studying the distribution of tracers naturally present in pore waters obtained from boreholes having crossed Mesozoic sedimentary series involving impervious and compacted clay rocks in the East (Andra borehole, EST433) and south of France (IRSN boreholes). Radial diffusion and vapour exchange methods were used to calculate the concentrations and diffusion parameters of the studied tracers. In Tournemire formations, the different profiles describe a curved shapes attributed to a diffusive exchange between the argillite pore water and the surrounding aquifers. Concerning the Mesozoic formations crossed by EST433, the study of the different profiles confirms the diffusion as the dominant transport mechanism in the Callovo-Oxfordian formation, and permits identifying the transport processes in the whole studied column from the Oxfordian formations down to the Liassic one. This study also helps to identify the Liassic formations as a major source of salinity of the Dogger aquifer

  9. EELS and electron diffraction studies on possible bonaccordite crystals in pressurized water reactor fuel CRUD and in oxide films of alloy 600 material

    Directory of Open Access Journals (Sweden)

    Jiaxin Chen

    2017-06-01

    Full Text Available Experimental verification of boron species in fuel CRUD (Chalk River Unidentified Deposit would provide essential and important information about the root cause of CRUD-induced power shifts (CIPS. To date, only bonaccordite and elemental boron were reported to exist in fuel CRUD in CIPS-troubled pressurized water reactor (PWR cores and lithium tetraborate to exist in simulated PWR fuel CRUD from some autoclave tests. We have reevaluated previous analysis of similar threadlike crystals along with examining some similar threadlike crystals from CRUD samples collected from a PWR cycle that had no indications of CIPS. These threadlike crystals have a typical [Ni]/[Fe] atomic ratio of ∼2 and similar crystal morphology as the one (bonaccordite reported previously. In addition to electron diffraction study, we have applied electron energy loss spectroscopy to determine boron content in such a crystal and found a good agreement with that of bonaccordite. Surprisingly, such crystals seem to appear also on corroded surfaces of Alloy 600 that was exposed to simulated PWR primary water with a dissolved hydrogen level of 5 mL H2/kg H2O, but absent when exposed under 75 mL H2/kg H2O condition. It remains to be verified as to what extent and in which chemical environment this phase would be formed in PWR primary systems.

  10. EELS and electron diffraction studies on possible bonaccordite crystals in pressurized water reactor fuel CRUD and in oxide films of alloy 600 material

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jiaxin [Studsvik Nuclear AB, Nykoping (Sweden); Lindberg, Fredrik [Swerea KIMAB AB, Kista (Sweden); Wells, Daniel [Electric Power Research Institute, Charlotte (United States); Bengysson, Bernt [Ringhals AB, Ringhalsverket, Varobacka (Sweden)

    2017-06-15

    Experimental verification of boron species in fuel CRUD (Chalk River Unidentified Deposit) would provide essential and important information about the root cause of CRUD-induced power shifts (CIPS). To date, only bonaccordite and elemental boron were reported to exist in fuel CRUD in CIPS-troubled pressurized water reactor (PWR) cores and lithium tetraborate to exist in simulated PWR fuel CRUD from some autoclave tests. We have reevaluated previous analysis of similar threadlike crystals along with examining some similar threadlike crystals from CRUD samples collected from a PWR cycle that had no indications of CIPS. These threadlike crystals have a typical [Ni]/[Fe] atomic ratio of ⁓2 and similar crystal morphology as the one (bonaccordite) reported previously. In addition to electron diffraction study, we have applied electron energy loss spectroscopy to determine boron content in such a crystal and found a good agreement with that of bonaccordite. Surprisingly, such crystals seem to appear also on corroded surfaces of Alloy 600 that was exposed to simulated PWR primary water with a dissolved hydrogen level of 5 mL H{sub 2}/kg H{sub 2}O, but absent when exposed under 75 mL H{sub 2}/kg H{sub 2}O condition. It remains to be verified as to what extent and in which chemical environment this phase would be formed in PWR primary systems.

  11. Understanding carbon nanotube channel formation in the lipid membrane

    Science.gov (United States)

    Choi, Moon-ki; Kim, Hyunki; Lee, Byung Ho; Kim, Teayeop; Rho, Junsuk; Kim, Moon Ki; Kim, Kyunghoon

    2018-03-01

    Carbon nanotubes (CNTs) have been considered a prominent nano-channel in cell membranes because of their prominent ion-conductance and ion-selectivity, offering agents for a biomimetic channel platform. Using a coarse-grained molecular dynamics simulation, we clarify a construction mechanism of vertical CNT nano-channels in a lipid membrane for a long period, which has been difficult to observe in previous CNT-lipid interaction simulations. The result shows that both the lipid coating density and length of CNT affect the suitable fabrication condition for a vertical and stable CNT channel. Also, simulation elucidated that a lipid coating on the surface of the CNT prevents the CNT from burrowing into the lipid membrane and the vertical channel is stabilized by the repulsion force between the lipids in the coating and membrane. Our study provides an essential understanding of how CNTs can form stable and vertical channels in the membrane, which is important for designing new types of artificial channels as biosensors for bio-fluidic studies.

  12. Understanding the kinetic mechanism of RNA single base pair formation.

    Science.gov (United States)

    Xu, Xiaojun; Yu, Tao; Chen, Shi-Jie

    2016-01-05

    RNA functions are intrinsically tied to folding kinetics. The most elementary step in RNA folding is the closing and opening of a base pair. Understanding this elementary rate process is the basis for RNA folding kinetics studies. Previous studies mostly focused on the unfolding of base pairs. Here, based on a hybrid approach, we investigate the folding process at level of single base pairing/stacking. The study, which integrates molecular dynamics simulation, kinetic Monte Carlo simulation, and master equation methods, uncovers two alternative dominant pathways: Starting from the unfolded state, the nucleotide backbone first folds to the native conformation, followed by subsequent adjustment of the base conformation. During the base conformational rearrangement, the backbone either retains the native conformation or switches to nonnative conformations in order to lower the kinetic barrier for base rearrangement. The method enables quantification of kinetic partitioning among the different pathways. Moreover, the simulation reveals several intriguing ion binding/dissociation signatures for the conformational changes. Our approach may be useful for developing a base pair opening/closing rate model.

  13. The autophagosome: current understanding of formation and maturation

    Directory of Open Access Journals (Sweden)

    Mannack LVJC

    2015-02-01

    Full Text Available Lilith VJC Mannack, Jon D Lane Cell Biology Laboratories, School of Biochemistry, University of Bristol, Bristol, UK Abstract: Autophagy is an important and highly conserved catabolic process with roles in development, homeostasis, and cellular stress responses. It describes various distinct pathways for the delivery of cytoplasmic materials (including misfolded protein aggregates and some organelles to the lysosome for degradation and component recycling. The best understood form of autophagy (macroautophagy describes the de novo assembly, maturation, and trafficking of a unique double membrane-bound organelle – the autophagosomes – that sequesters cytoplasmic materials and ultimately merges with the lysosomal compartment to form a degradative autolysosome. To rapidly assemble such a structure in response to stimuli, cells express a family of dedicated autophagy-related (ATG gene products that act sequentially to control membrane events leading first to the nucleation of an isolation membrane or phagophore, followed by phagophore expansion, and sealing to form an autophagosome that traffics to – and ultimately fuses with – the lysosome. These molecules are activated in response to upstream signaling pathways (notably, the mechanistic target of rapamycin [mTOR] pathway, and comprise protein and lipid kinases, putative membrane coats, and unique ubiquitin-like conjugation systems. In concert, a barrage of accessory proteins involved in various membrane trafficking pathways focused on the endosomal compartment are co-opted at the assembly site to facilitate autophagosome biogenesis. Understanding the integrated pathways that coordinate autophagosome assembly at the molecular level will be crucial if we are to realize the potential for autophagy manipulation in future disease therapies. Keywords: autophagy, ATG proteins, lysosome, phagophore, omegasome, autolysosome, membrane trafficking, ULK1, mTOR, PI(3 kinase, PI3P, LIR motif

  14. An Investigation of Teachers' Growing Understandings of the Picture Book Format

    Science.gov (United States)

    Martinez, Miriam G.; Harmon, Janis M.

    2015-01-01

    This study investigated the impact of a graduate course that focused on picture books on teachers' understandings of the picture book format and the ways in which these understandings influenced their self-reports of picture book use in the classroom. Findings of this qualitative investigation revealed that immersion in and analysis of the picture…

  15. Study of deposited crud composition on fuel surfaces in the environment of hydrogen water chemistry (HWC) of a Boiling Water Reactor at Chinshan Nuclear Power Plant

    International Nuclear Information System (INIS)

    Tsai, Tsuey-Lin; Lin, Tzung-Yi; Su, Te-Yen; Wen, Tung-Jen; Men, Lee-Chung

    2012-09-01

    This paper aimed at the characterization of metallic composition and surface analysis on the crud of fuel rods for unit-1 of BWR-4 at Nuclear Power Plant. The inductively coupled plasma- atomic emission spectroscopy (ICPAES) and the gamma spectrometry were carried out to analyze the corrosion product distributions and to determine the elemental compositions along the fuel rod under conditions of hydrogen water chemistry (HWC) switched from normal water chemistry (NWC) of reactor coolant in this study. Most of the crud consisted of the flakes and irregular shapes via SEM morphology. The loosely adherent oxide layer was mostly composed of hematite (α- Fe 2 O 3 ) with amorphous iron oxides by XRD results. The average deposited amounts of crud was the order of 0.5 mg/cm 2 , indicating that the fuel surface of this plant under HWC environment appeared to be one with the lower crud deposition in terms of low iron level of feedwater. It also showed no significant difference in comparison with NWC condition. (authors)

  16. Current Understanding of the Formation and Adaptation of Metabolic Systems Based on Network Theory

    Directory of Open Access Journals (Sweden)

    Kazuhiro Takemoto

    2012-07-01

    Full Text Available Formation and adaptation of metabolic networks has been a long-standing question in biology. With recent developments in biotechnology and bioinformatics, the understanding of metabolism is progressively becoming clearer from a network perspective. This review introduces the comprehensive metabolic world that has been revealed by a wide range of data analyses and theoretical studies; in particular, it illustrates the role of evolutionary events, such as gene duplication and horizontal gene transfer, and environmental factors, such as nutrient availability and growth conditions, in evolution of the metabolic network. Furthermore, the mathematical models for the formation and adaptation of metabolic networks have also been described, according to the current understanding from a perspective of metabolic networks. These recent findings are helpful in not only understanding the formation of metabolic networks and their adaptation, but also metabolic engineering.

  17. Embedded formative assessment and classroom process quality. How do they interact in promoting students' science understanding

    OpenAIRE

    Decristan, Jasmin; Klieme, Eckhard; Kunter, Mareike; Hochweber, Jan; Büttner, Gerhard; Fauth, Benjamin; Hondrich, Anna Lena; Rieser, Svenja; Hertel, Silke; Hardy, Ilonca

    2015-01-01

    In this study we examine the interplay between curriculum-embedded formative assessment-a well-known teaching practice-and general features of classroom process quality (i.e., cognitive activation, supportive climate, classroom management) and their combined effect on elementary school students' understanding of the scientific concepts of floating and sinking. We used data from a cluster-randomized controlled trial and compared curriculum-embedded formative assessment (17 classes) with a cont...

  18. Effect of Sulfur Concentration and PH Conditions on Akaganeite Formation: Understanding Akaganeite Formation Conditions in Yellowknife Bay, Gale Crater, Mars

    Science.gov (United States)

    Fox, A.; Peretyazhko, T.; Sutter, B.; Niles, P.; Ming, D. W.; Morris, R. V.

    2015-01-01

    The Chemistry and Mineralogy Instrument (CHEMIN) on board the Mars Science Laboratory (MSL) Curiosity Rover identified minor amounts of akaganeite (beta-FeOOH) at Yellowknife Bay, Mars. There is also evidence for akaganeite at other localities on Mars from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Akaganeite is an iron(III) hydroxide with a hollandite- like structure and Cl in its tunnels. Terrestrial akaganeite usually forms in Cl-rich environments under acidic, oxidizing conditions. Previous studies of akaganeite have revealed that akaganeite formation is affected by the presence of sulfate (hereafter denoted as S. The prediction of circumneutral pH coupled with the detection of S at Yellowknife Bay dictate that work is needed to determine how S and pH together affect akaganeite formation. The goal of this work is to study how changes in both S concentration and pH influence akaganeite precipitation. Akaganeite formation was investigated at S/Cl molar ratios of 0, 0.017, 0.083, 0.17 and 0.33 at pH 1.5, 2, and 4. Results are anticipated to provide combined S concentration and pH constraints on akaganeite formation in Yellowknife Bay and elsewhere on Mars. Knowledge of solution pH and S concentrations can be utilized in understanding microbial habitability potential on the Martian surface.

  19. Embedded Formative Assessment and Classroom Process Quality: How Do They Interact in Promoting Science Understanding?

    Science.gov (United States)

    Decristan, Jasmin; Klieme, Eckhard; Kunter, Mareike; Hochweber, Jan; Büttner, Gerhard; Fauth, Benjamin; Hondrich, A. Lena; Rieser, Svenja; Hertel, Silke; Hardy, Ilonca

    2015-01-01

    In this study we examine the interplay between curriculum-embedded formative assessment--a well-known teaching practice--and general features of classroom process quality (i.e., cognitive activation, supportive climate, classroom management) and their combined effect on elementary school students' understanding of the scientific concepts of…

  20. Model Building to Facilitate Understanding of Holliday Junction and Heteroduplex Formation, and Holliday Junction Resolution

    Science.gov (United States)

    Selvarajah, Geeta; Selvarajah, Susila

    2016-01-01

    Students frequently expressed difficulty in understanding the molecular mechanisms involved in chromosomal recombination. Therefore, we explored alternative methods for presenting the two concepts of the double-strand break model: Holliday junction and heteroduplex formation, and Holliday junction resolution. In addition to a lecture and…

  1. Control and understanding of kink formation in InAs-InP heterostructure nanowires.

    Science.gov (United States)

    Fahlvik Svensson, S; Jeppesen, S; Thelander, C; Samuelson, L; Linke, H; Dick, K A

    2013-08-30

    Nanowire heterostructures are of special interest for band structure engineering due to an expanded range of defect-free material combinations. However, the higher degree of freedom in nanowire heterostructure growth comes at the expense of challenges related to nanowire-seed particle interactions, such as undesired composition, grading and kink formation. To better understand the mechanisms of kink formation in nanowires, we here present a detailed study of the dependence of heterostructure nanowire morphology on indium pressure, nanowire diameter, and nanowire density. We investigate InAs-InP-InAs heterostructure nanowires grown with chemical beam epitaxy, which is a material system that allows for very abrupt heterointerfaces. Our observations indicate that the critical parameter for kink formation is the availability of indium, and that the resulting morphology is also highly dependent on the length of the InP segment. It is shown that kinking is associated with the formation of an inclined facet at the interface between InP and InAs, which destabilizes the growth and leads to a change in growth direction. By careful tuning of the growth parameters, it is possible to entirely suppress the formation of this inclined facet and thereby kinking at the heterointerface. Our results also indicate the possibility of producing controllably kinked nanowires with a high yield.

  2. Experimental Investigation on the Effects of Coolant Concentration on Sub-Cooled Boiling and Crud Deposition on Reactor Cladding at Prototypical PWR Operating Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Schultis, J., Kenneth; Fenton, Donald, L.

    2006-10-20

    Increasing demand for energy necessitates nuclear power units to increase power limits. This implies significant changes in the design of the core of the nuclear power units, therefore providing better performance and safety in operations. A major hindrance to the increase of nuclear reactor performance especially in Pressurized Deionized water Reactors (PWR) is Axial Offset Anomaly (AOA)--the unexpected change in the core axial power distribution during operation from the predicted distribution. This problem is thought to be occur because of precipitation and deposition of lithiated compounds like boric acid (H{sub 2}BO{sub 3}) and lithium metaborate (LiBO{sub 2}) on the fuel rod cladding. Deposited boron absorbs neutrons thereby affecting the total power distribution inside the reactor. AOA is thought to occur when there is sufficient build-up of crud deposits on the cladding during subcooled nucleate boiling. Predicting AOA is difficult as there is very little information regarding the heat and mass transfer during subcooled nucleate boiling. An experimental investigation was conducted to study the heat transfer characteristics during subcooled nucleate boiling at prototypical PWR conditions. Pool boiling tests were conducted with varying concentrations of lithium metaborate (LiBO{sub 2}) and boric acid (H{sub 2}BO{sub 3}) solutions in deionized water. The experimental data collected includes the effect of coolant concentration, subcooling, system pressure and heat flux on pool the boiling heat transfer coefficient. The analysis of particulate deposits formed on the fuel cladding surface during subcooled nucleate boiling was also performed. The results indicate that the pool boiling heat transfer coefficient degrades in the presence of boric acid and lithium metaborate compared to pure deionized water due to lesser nucleation. The pool boiling heat transfer coefficients decreased by about 24% for 5000 ppm concentrated boric acid solution and by 27% for 5000 ppm

  3. Towards an understanding of the role of clay minerals in crude oil formation, migration and accumulation

    Science.gov (United States)

    Wu, Lin Mei; Zhou, Chun Hui; Keeling, John; Tong, Dong Shen; Yu, Wei Hua

    2012-12-01

    This article reviews progress in the understanding of the role of clay minerals in crude oil formation, migration and accumulation. Clay minerals are involved in the formation of kerogen, catalytic cracking of kerogen into petroleum hydrocarbon, the migration of crude oil, and the continued change to hydrocarbon composition in underground petroleum reservoirs. In kerogen formation, clay minerals act as catalysts and sorbents to immobilize organic matter through ligand exchange, hydrophobic interactions and cation bridges by the mechanisms of Maillard reactions, polyphenol theory, selective preservation and sorptive protection. Clay minerals also serve as catalysts in acid-catalyzed cracking of kerogen into petroleum hydrocarbon through Lewis and Brønsted acid sites on the clay surface. The amount and type of clay mineral affect the composition of the petroleum. Brønsted acidity of clay minerals is affected by the presence and state of interlayer water, and displacement of this water is a probable driver in crude oil migration from source rocks. During crude oil migration and accumulation in reservoirs, the composition of petroleum is continually modified by interaction with clay minerals. The clays continue to function as sorbents and catalysts even while they are being transformed by diagenetic processes. The detail of chemical interactions and reaction mechanisms between clay minerals and crude oil formation remains to be fully explained but promises to provide insights with broader application, including catalytic conversion of biomass as a source of sustainable energy into the future.

  4. Benzene solubility in ionic liquids: working toward an understanding of liquid clathrate formation.

    Science.gov (United States)

    Pereira, Jorge F B; Flores, Luis A; Wang, Hui; Rogers, Robin D

    2014-11-17

    The solubility of benzene in 15 imidazolium, pyrrolidinium, pyridinium, and piperidinium ionic liquids has been determined; the resulting, benzene-saturated ionic liquid solutions, also known as liquid clathrates, were examined with (1) H and (19) F nuclear magnetic resonance spectroscopy to try and understand the molecular interactions that control liquid clathrate formation. The results suggest that benzene interacts primarily with the cation of the ionic liquid, and that liquid clathrate formation (and benzene solubility) is controlled by the strength of the cation-anion interactions, that is, the stronger the cation-anion interaction, the lower the benzene solubility. Other factors that were determined to be important in the final amount of benzene in any given liquid clathrate phase included attractive interactions between the anion and benzene (when significant), and larger steric or free volume demands of the ions, both of which lead to greater benzene solubility. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Understanding the process of social network evolution: Online-offline integrated analysis of social tie formation.

    Science.gov (United States)

    Kwak, Doyeon; Kim, Wonjoon

    2017-01-01

    It is important to consider the interweaving nature of online and offline social networks when we examine social network evolution. However, it is difficult to find any research that examines the process of social tie formation from an integrated perspective. In our study, we quantitatively measure offline interactions and examine the corresponding evolution of online social network in order to understand the significance of interrelationship between online and offline social factors in generating social ties. We analyze the radio signal strength indicator sensor data from a series of social events to understand offline interactions among the participants and measure the structural attributes of their existing online Facebook social networks. By monitoring the changes in their online social networks before and after offline interactions in a series of social events, we verify that the ability to develop an offline interaction into an online friendship is tied to the number of social connections that participants previously had, while the presence of shared mutual friends between a pair of participants disrupts potential new connections within the pre-designed offline social events. Thus, while our integrative approach enables us to confirm the theory of preferential attachment in the process of network formation, the common neighbor theory is not supported. Our dual-dimensional network analysis allows us to observe the actual process of social network evolution rather than to make predictions based on the assumption of self-organizing networks.

  6. Understanding Nanoemulsion Formation and Developing a Procedure for Porous Material Growth using Assembled Nanoemulsions

    Science.gov (United States)

    Yeranossian, Vahagn Frounzig

    Nanoemulsions as an emerging technology have found many applications in consumer products, drug delivery, and even particle formation. However, knowledge gaps exist in how some of these emulsions are formed, specifically what pathways are traversed to reach the final state. Moreover, how these pathways affect the final properties of the nanoemulsions would affect the applications that these droplets possess. Some nanoemulsions possess unique properties, including the assembly of droplets. While the assembly of droplets is being studied in the Helgeson lab, work must be done to understand how the assembly itself could be used to control the growth of porous materials, such a hydrogels. Thus, this thesis aims to address two factors of nanoemulsions: the formation of water-in-oil nanoemulsions and the use of assemblying droplets in oil-in-water nanoemulsions to form macroporous hydrogels. To elucidate the formation mechanism of water-in-oil nanoemulsions, a combination of dynamic light scattering and small angle neutron scattering were used to study the intermediate and final states of the nanoemulsion during its formation. These nanoemulsions were prepared by slowly adding water to an oil and surfactant mixture and were diluted to effectively measure using scattering techniques without multiple scattering events. To develop a procedure to use assembled nanoemulsions for the growth of porous materials, a combination of optical microscopy and diffusional studies were employed. Optical microscopy images taken at various stages of the procedure help elucidate how the pore sizes of the final porous material is related to the droplet-rich domains of the assembled nanoemulsion. Meanwhile, diffusional measurements help confirm the size and interconnectedness of the macropores. From the work done in the completion of my thesis, the formation mechanism of the water-in-oil nanoemulsion studied has been elucidated. The neutron scattering measurements show that during the

  7. Understanding adult neurogenesis beyond its role in learning and memory formation

    Directory of Open Access Journals (Sweden)

    Ab Latif Wani

    2017-04-01

    Full Text Available There has been a shift in the understanding of brain, neurons, and their functional role over the last two decades. Earlier it was believed that the brain was a static organ and was not subject to any change throughout life. An understanding was developed later that brain reorganizes its structure by a specific property called neuroplasticity. Recent research shows that the brain generates new neurons even in the adult stage, and this process is called adult neurogenesis. Although researchers still not have all the answers about the newborn neurons, and why and how they are generated, and what is their role, some have highlighted the importance of these in learning and memory formation, and even in memories of fear and spatial navigation. A wide range of environmental experience influences the generation of newborn neurons and their functional variability. There are questions about how different environmental experiences cause the differences in the generation of new neurons. Recently the field of optogenetics attempted to answer the questions on adult neurogenesis. However there are still questions about adult neurogenesis which needs a more naturalistic approach, for their better understanding.

  8. Using Spin to Understand the Formation of LIGO and Virgo’s Black Holes

    Science.gov (United States)

    Farr, Ben; Holz, Daniel E.; Farr, Will M.

    2018-02-01

    With the growing number of binary black hole (BBH) mergers detected by the Advanced LIGO and Virgo detectors, it is becoming possible to constrain the properties of the underlying population and better understand the formation of these systems. Black hole (BH) spin orientations are one of the cleanest discriminators of formation history, with BHs in dynamically formed binaries in dense stellar environments expected to have spins distributed isotropically, in contrast to isolated populations where stellar evolution is expected to induce spins preferentially aligned with the orbital angular momentum. In this work, we propose a simple, model-agnostic approach to characterizing the spin properties of LIGO/Virgo’s BBH population. Using measurements of the effective spin of the binaries, we introduce a simple parameter to quantify the fraction of the population that is isotropically distributed, regardless of the spin magnitude distribution of the population. Once the orientation characteristics of the population have been determined, we show how measurements of effective spin can be used to directly constrain the BH spin magnitude distribution. We find that most effective spin measurements are too small to be informative, with the first four events showing a slight preference for a population with alignment, with an odds ratio of 1.2. We argue that it will be possible to distinguish symmetric and anti-symmetric populations at high confidence with tens of additional detections, although mixed populations may take significantly longer to disentangle. We also derive BH spin magnitude distributions from LIGO’s first four BBHs under the assumption of aligned or isotropic populations.

  9. Applying Chemical Imaging Analysis to Improve Our Understanding of Cold Cloud Formation

    Science.gov (United States)

    Laskin, A.; Knopf, D. A.; Wang, B.; Alpert, P. A.; Roedel, T.; Gilles, M. K.; Moffet, R.; Tivanski, A.

    2012-12-01

    The impact that atmospheric ice nucleation has on the global radiation budget is one of the least understood problems in atmospheric sciences. This is in part due to the incomplete understanding of various ice nucleation pathways that lead to ice crystal formation from pre-existing aerosol particles. Studies investigating the ice nucleation propensity of laboratory generated particles indicate that individual particle types are highly selective in their ice nucleating efficiency. This description of heterogeneous ice nucleation would present a challenge when applying to the atmosphere which contains a complex mixture of particles. Here, we employ a combination of micro-spectroscopic and optical single particle analytical methods to relate particle physical and chemical properties with observed water uptake and ice nucleation. Field-collected particles from urban environments impacted by anthropogenic and marine emissions and aging processes are investigated. Single particle characterization is provided by computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). A particle-on-substrate approach coupled to a vapor controlled cooling-stage and a microscope system is applied to determine the onsets of water uptake and ice nucleation including immersion freezing and deposition ice nucleation as a function of temperature (T) as low as 200 K and relative humidity (RH) up to water saturation. We observe for urban aerosol particles that for T > 230 K the oxidation level affects initial water uptake and that subsequent immersion freezing depends on particle mixing state, e.g. by the presence of insoluble particles. For T cloud formation. Initial results applying single particle IN analysis using CCSEM/EDX and STXM/NEXAFS reveal that a significant amount of IN are coated by organics and, thus, are similar to the

  10. Understanding the role of contextual cues in supporting the formation of medication-taking habits

    Directory of Open Access Journals (Sweden)

    Katarzyna Stawarz

    2015-10-01

    in the presence of stable cues, with time they start to guide the behaviour and provide triggers to action (Lally & Gardner, 2011. However, adherence technologies tend to disregard contextual cues and the habitual nature of many medication regimens, and instead alert users when it is time to take the pill (Stawarz et al., 2014. Similarly, behaviour change technologies designed specifically to support habit formation also neglect contextual cues and instead focus on behaviour tracking and reminders (Stawarz et al, 2015. By supporting the identification and reinforcement of contextual cues, technology could aid both prospective memory and habit formation: it could help patients remember the new regimen and turn it into a reliable medication habit. Aims: Previous research by Stawarz et al. (2015 suggests that contextual cues support habit formation, but because habits take time to develop, people can still forget; conversely, reminders support remembering, but they can inhibit habit development. However, their study measured the development of an artificial habit (texting the researchers, lasted only for 4 weeks, and did not account for the role of location as a contextual cue. Therefore, the aim of this study was to explore the impact of contextual cues and reminders on the development of automaticity of behaviour (representing habit strength and frequency of repetition (representing adherence to the regimen over a longer period and with behaviours participants wanted to turn into habit. The understanding of how these factors influence the process of habit formation would enable us to design more effective adherence technologies that assist patients when they start a new regimen (prospective memory support as well as over the long term (habit support. Method: 209 participants were recruited on social networks, and among students and university staff. They were 18-58 years old (mean age = 27, SD = 7.6 years; 68% were women, 74% were students. They were asked to repeat a

  11. Toward an understanding of surface layer formation, growth, and transformation at the glass-fluid interface

    Science.gov (United States)

    Hopf, J.; Eskelsen, J. R.; Chiu, M.; Ievlev, A. V.; Ovchinnikova, O. S.; Leonard, D.; Pierce, E. M.

    2018-05-01

    Silicate glass is a metastable and durable solid that has application to a number of energy and environmental challenges (e.g., microelectronics, fiber optics, and nuclear waste storage). If allowed to react with water over time silicate glass develops an altered layer at the solid-fluid interface. In this study, we used borosilicate glass (LAWB45) as a model material to develop a robust understanding of altered layer formation (i.e., amorphous hydrated surface layer and crystalline reaction products). Experiments were conducted at high surface area-to-volume ratio (∼200,000 m-1) and 90 °C in the pressurized unsaturated flow (PUF) apparatus for 1.5-years to facilitate the formation of thick altered layers and allow for the effluent solution chemistry to be monitored continuously. A variety of microscopy techniques were used to characterize reacted grains and suggest the average altered layer thickness is 13.2 ± 8.3 μm with the hydrated and clay layer representing 74.8% and 25.2% of the total altered layer, respectively. The estimate of hydrated layer thickness is within the experimental error of the value estimated from the B release rate data (∼10 ± 1 μm/yr) over the 1.5-year duration. PeakForce® quantitative nanomechanical mapping results suggest the hydrated layer has a modulus that ranges between ∼20 and 40 GPa, which is in the range of porous silica that contains from ∼20 to ∼50% porosity, yet significantly lower than dense silica (∼70-80 GPa). Scanning transmission electron microscopy (STEM) images confirm the presence of pores and an analysis of a higher resolution image provides a qualitative estimate of ≥22% porosity in the hydrated layer with variations in void volume with increasing distance from the unaltered glass. Chemical composition analyses, based on a combination of time-of-flight secondary-ion mass spectrometry (ToF-SIMS), scanning electron microscopy with X-ray energy dispersive spectroscopy (EDS), and STEM-EDS, clearly show

  12. A force sensor using nanowire arrays to understand biofilm formation (Conference Presentation)

    Science.gov (United States)

    Sahoo, Prasana K.; Cavalli, Alessandro; Pelegati, Vitor B.; Murillo, Duber M.; Souza, Alessandra A.; Cesar, Carlos L.; Bakkers, Erik P. A. M.; Cotta, Monica A.

    2016-03-01

    Understanding the cellular signaling and function at the nano-bio interface can pave the way towards developing next-generation smart diagnostic tools. From this perspective, limited reports detail so far the cellular and subcellular forces exerted by bacterial cells during the interaction with abiotic materials. Nanowire arrays with high aspect ratio have been used to detect such small forces. In this regard, live force measurements were performed ex-vivo during the interaction of Xylella fastidiosa bacterial cells with InP nanowire arrays. The influence of nanowire array topography and surface chemistry on the response and motion of bacterial cells was studied in detail. The nanowire arrays were also functionalized with different cell adhesive promoters, such as amines and XadA1, an afimbrial protein of X.fastidiosa. By employing the well-defined InP nanowire arrays platform, and single cell confocal imaging system, we were able to trace the bacterial growth pattern, and show that their initial attachment locations are strongly influenced by the surface chemistry and nanoscale surface topography. In addition, we measure the cellular forces down to few nanonewton range using these nanowire arrays. In case of nanowire functionalized with XadA1, the force exerted by vertically and horizontally attached single bacteria on the nanowire is in average 14% and 26% higher than for the pristine array, respectively. These results provide an excellent basis for live-cell force measurements as well as unravel the range of forces involved during the early stages of bacterial adhesion and biofilm formation.

  13. Understanding Educational Policy Formation: The Case of School Violence Policies in Israel

    Science.gov (United States)

    Fast, Idit

    2016-01-01

    This study explores mechanisms underlying processes of educational policy formation. Previous studies have given much attention to processes of diffusion when accounting for educational policy formation. Less account has been given to the day-to-day institutional dynamics through which educational policies develop and change. Building on extensive…

  14. Quantification of Release of Critical Elements, Formation of Fly Ash and Aerosols: Status on Current Understanding and Research Needs

    DEFF Research Database (Denmark)

    Jappe Frandsen, Flemming

    2017-01-01

    is that there are still in 2017, a number of big gaps in our current understanding of these phenomena, and that we need focus on these points, in order to be able to describe, understand, and, quantify the processes of ash and deposit formation completely [Frandsen, 2009].This paper provide a brief outline of the current......) shedding of deposits. Some of the steps may be repetitive, as the process is partly cyclic [Frandsen, 2011]. The inorganic fraction of solid fuels, may cause several problems during combustion, most importantly formation of particulate matter (aerosols and fly ashes). These may subsequently induce deposit...... of combustion units.Through several years, high quality research has been conducted on characterization of fuels, ashes and deposit formation in utility boilers fired with coal, biomass and waste fractions. Huge amounts of experimental data have been reported, from such work, but the fact...

  15. Understanding visual map formation through vortex dynamics of spin Hamiltonian models.

    Science.gov (United States)

    Cho, Myoung Won; Kim, Seunghwan

    2004-01-09

    The pattern formation in orientation and ocular dominance columns is one of the most investigated problems in the brain. From a known cortical structure, we build spinlike Hamiltonian models with long-range interactions of the Mexican hat type. These Hamiltonian models allow a coherent interpretation of the diverse phenomena in the visual map formation with the help of relaxation dynamics of spin systems. In particular, we explain various phenomena of self-organization in orientation and ocular dominance map formation including the pinwheel annihilation and its dependency on the columnar wave vector and boundary conditions.

  16. Understanding the effect of substitution on the formation of S... F ...

    Indian Academy of Sciences (India)

    ias.ac.in/article/fulltext/jcsc/128/10/1589-1596 ... The formation of S. . .F chalcogen bonds was observed in all the cases, except for X = −H. The binding energy of the S. . .F non-covalent interactions is strongly dependent on the nature of the ...

  17. Towards the understanding of structure formation and dynamics in bio-nano systems

    DEFF Research Database (Denmark)

    Yakubovich, Alexander V.; Solov'yov, Ilia; Solov'yov, Andrey V.

    2008-01-01

    This paper gives an overview of a number of key structure formation processes involving the well known biomolecular and nano objects such as fullerenes, nanotubes, polypeptides, proteins and DNA molecules. We formulate the problems, describe the main experimental observations and theoretical...

  18. Pregnancy Resolution and Family Formation: Understanding Gender Differences in Adolescents' Preferences and Beliefs.

    Science.gov (United States)

    Marsiglio, William; Menaghan, Elizabeth G.

    1990-01-01

    Examined gender differences in adolescents' personal views about pregnancy resolution and family formation. Surveyed adolescents (n=577) using vignette involving unplanned pregnancy. Findings showed similar percentages of males and females preferred abortion and adoption as strategies for handling pregnancy, but females were more likely to select…

  19. Molecular understanding of atmospheric particle formation from sulfuric acid and large oxidized organic molecules.

    Science.gov (United States)

    Schobesberger, Siegfried; Junninen, Heikki; Bianchi, Federico; Lönn, Gustaf; Ehn, Mikael; Lehtipalo, Katrianne; Dommen, Josef; Ehrhart, Sebastian; Ortega, Ismael K; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Hutterli, Manuel; Duplissy, Jonathan; Almeida, João; Amorim, Antonio; Breitenlechner, Martin; Downard, Andrew J; Dunne, Eimear M; Flagan, Richard C; Kajos, Maija; Keskinen, Helmi; Kirkby, Jasper; Kupc, Agnieszka; Kürten, Andreas; Kurtén, Theo; Laaksonen, Ari; Mathot, Serge; Onnela, Antti; Praplan, Arnaud P; Rondo, Linda; Santos, Filipe D; Schallhart, Simon; Schnitzhofer, Ralf; Sipilä, Mikko; Tomé, António; Tsagkogeorgas, Georgios; Vehkamäki, Hanna; Wimmer, Daniela; Baltensperger, Urs; Carslaw, Kenneth S; Curtius, Joachim; Hansel, Armin; Petäjä, Tuukka; Kulmala, Markku; Donahue, Neil M; Worsnop, Douglas R

    2013-10-22

    Atmospheric aerosols formed by nucleation of vapors affect radiative forcing and therefore climate. However, the underlying mechanisms of nucleation remain unclear, particularly the involvement of organic compounds. Here, we present high-resolution mass spectra of ion clusters observed during new particle formation experiments performed at the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research. The experiments involved sulfuric acid vapor and different stabilizing species, including ammonia and dimethylamine, as well as oxidation products of pinanediol, a surrogate for organic vapors formed from monoterpenes. A striking resemblance is revealed between the mass spectra from the chamber experiments with oxidized organics and ambient data obtained during new particle formation events at the Hyytiälä boreal forest research station. We observe that large oxidized organic compounds, arising from the oxidation of monoterpenes, cluster directly with single sulfuric acid molecules and then form growing clusters of one to three sulfuric acid molecules plus one to four oxidized organics. Most of these organic compounds retain 10 carbon atoms, and some of them are remarkably highly oxidized (oxygen-to-carbon ratios up to 1.2). The average degree of oxygenation of the organic compounds decreases while the clusters are growing. Our measurements therefore connect oxidized organics directly, and in detail, with the very first steps of new particle formation and their growth between 1 and 2 nm in a controlled environment. Thus, they confirm that oxidized organics are involved in both the formation and growth of particles under ambient conditions.

  20. N-body simulations of planet formation: understanding exoplanet system architectures

    Science.gov (United States)

    Coleman, Gavin; Nelson, Richard

    2015-12-01

    Observations have demonstrated the existence of a significant population of compact systems comprised of super-Earths and Neptune-mass planets, and a population of gas giants that appear to occur primarily in either short-period (100 days) orbits. The broad diversity of system architectures raises the question of whether or not the same formation processes operating in standard disc models can explain these planets, or if different scenarios are required instead to explain the widely differing architectures. To explore this issue, we present the results from a comprehensive suite of N-body simulations of planetary system formation that include the following physical processes: gravitational interactions and collisions between planetary embryos and planetesimals; type I and II migration; gas accretion onto planetary cores; self-consistent viscous disc evolution and disc removal through photo-evaporation. Our results indicate that the formation and survival of compact systems of super-Earths and Neptune-mass planets occur commonly in disc models where a simple prescription for the disc viscosity is assumed, but such models never lead to the formation and survival of gas giant planets due to migration into the star. Inspired in part by the ALMA observations of HL Tau, and by MHD simulations that display the formation of long-lived zonal flows, we have explored the consequences of assuming that the disc viscosity varies in both time and space. We find that the radial structuring of the disc leads to conditions in which systems of giant planets are able to form and survive. Furthermore, these giants generally occupy those regions of the mass-period diagram that are densely populated by the observed gas giants, suggesting that the planet traps generated by radial structuring of protoplanetary discs may be a necessary ingredient for forming giant planets.

  1. Molecular understanding of atmospheric particle formation from sulfuric acid and large oxidized organic molecules

    CERN Document Server

    Schobesberger, Siegfried; Bianchi, Federico; Lönn, Gustaf; Ehn, Mikael; Lehtipalo, Katrianne; Dommen, Josef; Ehrhart, Sebastian; Ortega, Ismael K; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Hutterli, Manuel; Duplissy, Jonathan; Almeida, João; Amorim, Antonio; Breitenlechner, Martin; Downard, Andrew J; Dunne, Eimear M; Flagan, Richard C; Kajos, Maija; Keskinen, Helmi; Kirkby, Jasper; Kupc, Agnieszka; Kürten, Andreas; Kurtén, Theo; Laaksonen, Ari; Mathot, Serge; Onnela, Antti; Praplan, Arnaud P; Rondo, Linda; Santos, Filipe D; Schallhart, Simon; Schnitzhofer, Ralf; Sipilä, Mikko; Tomé, António; Tsagkogeorgas, Georgios; Vehkamäki, Hanna; Wimmer, Daniela; Baltensperger, Urs; Carslaw, Kenneth S; Curtius, Joachim; Hansel, Armin; Petäjä, Tuukka; Kulmala, Markku; Donahue, Neil M; Worsnop, Douglas R

    2013-01-01

    Atmospheric aerosols formed by nucleation of vapors affect radiative forcing and therefore climate. However, the underlying mechanisms of nucleation remain unclear, particularly the involvement of organic compounds. Here, we present high-resolution mass spectra of ion clusters observed during new particle formation experiments performed at the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research. The experiments involved sulfuric acid vapor and different stabilizing species, including ammonia and dimethylamine, as well as oxidation products of pinanediol, a surrogate for organic vapors formed from monoterpenes. A striking resemblance is revealed between the mass spectra from the chamber experiments with oxidized organics and ambient data obtained during new particle formation events at the Hyytiälä boreal forest research station. We observe that large oxidized organic compounds, arising from the oxidation of monoterpenes, cluster directly with single sulfuric acid molec...

  2. Control analysis as a tool to understand the formation of the las operon in Lactococcus lactis

    DEFF Research Database (Denmark)

    Købmann, Brian Jensen; Solem, Christian; Jensen, Peter Ruhdal

    2005-01-01

    In Lactococcus lactis the enzymes phosphofructokinase (PFK), pyruvate kinase (PK) and lactate dehydrogenase (LDH) are uniquely encoded in the las operon and we here apply Metabolic Control Analysis to study the role of this organisation. Earlier work showed that LDH at wildtype level has zero...... control on formate and acetate production, whereas PFK has no control on these fluxes. Decreased expression of the entire las operon resulted in a strong decrease in growth rate and the glycolytic flux; at 53% expression of the las operon the glycolytic flux was reduced to 44% and the flux control...... coefficient found for the entire operon; the strong positive control by PK almost cancels out the negative control by LDH on formate production. The analysis suggests that co-regulation of PFK and PK provides a very efficient way to regulate glycolysis, and co-regulating PK and LDH allows the cells...

  3. Control of Listeria monocytogenes in the processing environment by understanding biofilm formation and resistance to sanitizers.

    Science.gov (United States)

    Manios, Stavros G; Skandamis, Panagiotis N

    2014-01-01

    Listeria monocytogenes can colonize in the food processing environment and thus pose a greater risk of cross-contamination to food. One of the proposed mechanisms that facilitates such colonization is biofilm formation. As part of a biofilm, it is hypothesized that L. monocytogenes can survive sanitization procedures. In addition, biofilms are difficult to remove and may require additional physical and chemical mechanisms to reduce their presence and occurrence. The initial stage of biofilm formation is attachment to surfaces, and therefore it is important to be able to determine the ability of L. monocytogenes strains to attach to various inert surfaces. In this chapter, methods to study bacterial attachment to surfaces are described. Attachment is commonly induced by bringing planktonic cells into contact with plastic, glass, or stainless steel surfaces with or without food residues ("soil") in batch or continuous (e.g., with constant flow of nutrients) culture. Measurement of biofilm formed is carried out by detaching cells (with various mechanical methods) and measuring the viable counts or by measuring the total attached biomass. Resistance of biofilms to sanitizers is commonly carried out by exposure of the whole model surface bearing the attached cells to a solution of sanitizer, followed by measuring the survivors as described above.

  4. The contribution of tracers in understanding transportation processes in indurated argillaceous formations

    International Nuclear Information System (INIS)

    Savoye, Sebastien

    2008-01-01

    In a first part, the author recalls briefly the properties of the two argillaceous formations studied in this HDR report: the Toarcian/Domerian argillite and the Opalinus clay of Mont Terri. At first, have been described the two undamaged argillite materials and then the damaged Tournemire argillite. The second part gives the results obtained from the researches on the undamaged rock with natural tracers and with approaches using artificial tracers. The third part deals with the study of the damaged rock in separating natural perturbations of those of anthropogenic origin. At last, the conclusion gives the guiding thema of this research work and the main long-term future prospects that may result. (O.M.)

  5. Understanding Passive Layer Formation for Further Corrosion Management in Gas Production Pipes

    Science.gov (United States)

    Santoso, R. K.; Rahmawati, S. D.; Gadesa, A.; Wahyuningrum, D.

    2017-07-01

    Corrosion is a critical issue during the development of a gas field, especially wet gas or retrograde gas field. Corrosion affects the management system of a field and further impacts the amount of investment. Therefore, accurate prediction of corrosion rate is needed to plan an effective preventive action before going further to the development phase. One of the important parameters that should be noticed to create an accurate prediction is the formation of the passive layer. In CO2-H2S environment, there will be three possibilities of passive layer: FeS, FeCO3 or no passive layer. In this study, we create mathematical models to determine the formed passive layer in each segment of the gas production tubing and pipeline. The model is built using Faraday’s Law and Thermodynamic approach to account the passive layer formation at different temperature, pH, corrosion rate and partial pressure of CO2 and H2S. From the simulation, it was found that there were three boundary conditions: no scale-FeS boundary, no scale-FeCO3 boundary and FeS-FeCO3 boundary. The first two boundaries evolved over a time as the concentration of Fe2+ ions was increasing. However, FeS-FeCO3 boundary remained steady as it was not affected by the addition of Fe2+ ions. Using sample case study, few variations were noticed at production pipeline and tubing. It was caused by the gas composition, which contained high CO2 and very low H2S. Boundary conditions only changed slightly over two days period.

  6. Understanding the physics of gas stripping and star-formation quenching of the satellite dwarf galaxies in the Local Group

    Science.gov (United States)

    Wetzel, Andrew

    2017-08-01

    The Milky Way (MW) and M31 are among the best systems to study the physics of the halo environment on galaxy evolution. Nearly all of the satellite dwarf galaxies of the MW and M31 are gas-poor and have quenched star formation. Over 1200 orbits of HST observations of these satellites now provide detailed star-formation histories and proper-motion velocities for full 6-D orbital phase-space, informing both when and where each satellite quenched. However, the lack of sufficiently realistic theoretical models of gas stripping represents a severe limitation to leveraging the astrophysical returns of these HST observations.We propose to use the new Latte cosmological zoom-in hydrodynamic simulations of MW- and M31-mass systems to understand the environmental processes that strip gas from satellite dwarf galaxies and quench their star formation. Our initial Latte simulations form realistic satellite populations, with star-formation histories that agree well HST measurements. These simulations use the state-of-the-art FIRE model for star formation and feedback: this feedback drives strong gas outflows within dwarf galaxies that can enhance the efficiency of ram-pressure stripping within the halo. We will run a new suite of simulations carefully targeted to the Local Group, and we will investigate how the combination of internal feedback and external stripping leads to rapid quenching, as observed by HST. Finally, we will publicly release our satellite galaxy/subhalo catalogs, including their full orbital and star-formation histories, to compare with existing/upcoming HST observations, providing detailed insight into the physics of environmental quenching.

  7. Understanding non-enzymatic aminophospholipid glycation and its inhibition. Polar head features affect the kinetics of Schiff base formation.

    Science.gov (United States)

    Caldés, Catalina; Vilanova, Bartolomé; Adrover, Miquel; Muñoz, Francisco; Donoso, Josefa

    2011-08-01

    Non-enzymatic aminophospholipid glycation is an especially important process because it alters the stability of lipid bilayers and interferes with cell function and integrity as a result. However, the kinetic mechanism behind this process has scarcely been studied. As in protein glycation, the process has been suggested to involve the formation of a Schiff base as the initial, rate-determining step. In this work, we conducted a comparative kinetic study of Schiff base formation under physiological conditions in three low-molecular weight analogues of polar heads in the naturally occurring aminophospholipids O-phosphorylethanolamine (PEA), O-phospho-DL-serine (PSer) and 2-aminoethylphenethylphosphate (APP) with various glycating carbonyl compounds (glucose, arabinose and acetol) and the lipid glycation inhibitor pyridoxal 5'-phosphate (PLP). Based on the results, the presence of a phosphate group and a carboxyl group in α position respect to the amino group decrease the formation constant for the Schiff base relative to amino acids. On the other hand, esterifying the phosphate group with a non-polar substituent in APP increases the stability of its Schiff base. The observed kinetic formation constants of aminophosphates with carbonyl groups were smaller than those for PLP. Our results constitute an important contribution to understanding the competitive inhibition effect of PLP on aminophospholipid glycation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. A contribution to the understanding of the high burn-up structure formation in nuclear fuels

    International Nuclear Information System (INIS)

    Jonnet, J.

    2007-01-01

    An increase of the discharge burn-up of UO 2 nuclear fuels in the light water reactors results in the appearance of a change of microscopic structure, called HBS. Although well characterised experimentally, important points on the mechanisms of its formation remain to be cleared up. In order to answer these questions, a study of the contribution of the dislocation-type defects was conducted. In a first part, a calculation method of the stress field associated with periodic configurations of dislocations was developed. The method was applied to the cases of edge dislocation pile-up and wall, for which an explicit expression of the internal stress potential was obtained. Through the study of other examples of dislocation configurations, it was highlighted that this method also allows the calculation of any periodic dislocation configuration. In a second part, the evolution of interstitial-type dislocation loops was studied in UO 2 fuel samples doped with 10% in mass of alpha emitters. The experimental loop size distributions were obtained for these samples stored during 4 and 7 years at room temperature. Kinetic equations are proposed in order to study the influence of the resolution process of interstitials from a loop back to the matrix due to an impact with the recoil atom 234 U, as well as the coalescence of two interstitial loops that can diffuse by a volume mechanism. The application of the model shows that the two processes must be considered in the study of the evolution of radiation damage. (author)

  9. Formation, function, and exhaustion of notochordal cytoplasmic vacuoles within intervertebral disc: current understanding and speculation.

    Science.gov (United States)

    Wang, Feng; Gao, Zeng-Xin; Cai, Feng; Sinkemani, Arjun; Xie, Zhi-Yang; Shi, Rui; Wei, Ji-Nan; Wu, Xiao-Tao

    2017-08-22

    Notochord nucleus pulposus cells are characteristic of containing abundant and giant cytoplasmic vacuoles. This review explores the embryonic formation, biological function, and postnatal exhaustion of notochord vacuoles, aiming to characterize the signal network transforming the vacuolated nucleus pulposus cells into the vacuole-less chondrocytic cells. Embryonically, the cytoplasmic vacuoles within vertebrate notochord originate from an evolutionarily conserved vacuolation process during neurulation, which may continue to provide mechanical and signal support in constructing a mammalian intervertebral disc. For full vacuolation, a vacuolating specification from dorsal organizer cells, synchronized convergent extension, well-structured notochord sheath, and sufficient post-Golgi trafficking in notochord cells are required. Postnatally, age-related and species-specific exhaustion of vacuolated nucleus pulposus cells could be potentiated by Fas- and Fas ligand-induced apoptosis, intolerance to mechanical stress and nutrient deficiency, vacuole-mediated proliferation check, and gradual de-vacuolation within the avascular and compression-loaded intervertebral disc. These results suggest that the notochord vacuoles are active and versatile organelles for both embryonic notochord and postnatal nucleus pulposus, and may provide novel information on intervertebral disc degeneration to guide cell-based regeneration.

  10. Caustic-based approach to understanding bunching dynamics and current spike formation in particle bunches

    Directory of Open Access Journals (Sweden)

    T. K. Charles

    2016-10-01

    Full Text Available Current modulations, current spikes, and current horns, are observed in a range of accelerator physics applications including strong bunch compression in Free Electron Lasers and linear colliders, trains of microbunching for terahertz radiation, microbunching instability and many others. This paper considers the fundamental mechanism that drives intense current modulations in dispersive regions, beyond the common explanation of nonlinear and higher-order effects. Under certain conditions, neighboring electron trajectories merge to form caustics, and often result in characteristic current spikes. Caustic lines and surfaces are regions of maximum electron density, and are witnessed in accelerator physics as folds in phase space of accelerated bunches. We identify the caustic phenomenon resulting in cusplike current profiles and derive an expression which describes the conditions needed for particle-bunch caustic formation in dispersive regions. The caustic expression not only reveals the conditions necessary for caustics to form but also where in longitudinal space the caustics will form. Particle-tracking simulations are used to verify these findings. We discuss the broader implications of this work including how to utilize the caustic expression for manipulation of the longitudinal phase space to achieve a desired current profile shape.

  11. Advances in the formation, use and understanding of multi-cellular spheroids.

    Science.gov (United States)

    Achilli, Toni-Marie; Meyer, Julia; Morgan, Jeffrey R

    2012-10-01

    Developing in vitro models for studying cell biology and cell physiology is of great importance to the fields of biotechnology, cancer research, drug discovery, toxicity testing, as well as the emerging fields of tissue engineering and regenerative medicine. Traditional two-dimensional (2D) methods of mammalian cell culture have several limitations and it is increasingly recognized that cells grown in a three-dimensional (3D) environment more closely represent normal cellular function due to the increased cell-to-cell interactions, and by mimicking the in vivo architecture of natural organs and tissues. In this review, we discuss the methods to form 3D multi-cellular spheroids, the advantages and limitations of these methods, and assays used to characterize the function of spheroids. The use of spheroids has led to many advances in basic cell sciences, including understanding cancer cell interactions, creating models for drug discovery and cancer metastasis, and they are being investigated as basic units for engineering tissue constructs. As so, this review will focus on contributions made to each of these fields using spheroid models. Multi-cellular spheroids are rich in biological content and mimic better the in vivo environment than 2D cell culture. New technologies to form and analyze spheroids are rapidly increasing their adoption and expanding their applications.

  12. The role of mathematical models in understanding pattern formation in developmental biology.

    Science.gov (United States)

    Umulis, David M; Othmer, Hans G

    2015-05-01

    In a Wall Street Journal article published on April 5, 2013, E. O. Wilson attempted to make the case that biologists do not really need to learn any mathematics-whenever they run into difficulty with numerical issues, they can find a technician (aka mathematician) to help them out of their difficulty. He formalizes this in Wilsons Principle No. 1: "It is far easier for scientists to acquire needed collaboration from mathematicians and statisticians than it is for mathematicians and statisticians to find scientists able to make use of their equations." This reflects a complete misunderstanding of the role of mathematics in all sciences throughout history. To Wilson, mathematics is mere number crunching, but as Galileo said long ago, "The laws of Nature are written in the language of mathematics[Formula: see text] the symbols are triangles, circles and other geometrical figures, without whose help it is impossible to comprehend a single word." Mathematics has moved beyond the geometry-based model of Galileo's time, and in a rebuttal to Wilson, E. Frenkel has pointed out the role of mathematics in synthesizing the general principles in science (Both point and counter-point are available in Wilson and Frenkel in Notices Am Math Soc 60(7):837-838, 2013). We will take this a step further and show how mathematics has been used to make new and experimentally verified discoveries in developmental biology and how mathematics is essential for understanding a problem that has puzzled experimentalists for decades-that of how organisms can scale in size. Mathematical analysis alone cannot "solve" these problems since the validation lies at the molecular level, but conversely, a growing number of questions in biology cannot be solved without mathematical analysis and modeling. Herein, we discuss a few examples of the productive intercourse between mathematics and biology.

  13. Entropic effects in formation of chromosome territories: towards understanding of radiation-induced gene translocation frequency

    Science.gov (United States)

    Gudowska-Nowak, Ewa; Ritter, Sylvia; Durante, Marco; Deperas-Standylo, Joanna; Ciesla, Michal

    2012-07-01

    A detailed understanding of structural organization of biological target, such as geometry of an inter-phase chromosome, is an essential prerequisite for gaining deeper insight into relationship between radiation track structure and radiation-induced biological damage [1]. In particular, coupling of biophysical models aimed to describe architecture of chromosomes and their positioning in a cell nucleus [2-4] with models of local distribution of ionizations caused by passing projectiles, are expected to result in more accurate estimates of aberration induction caused by radiation. There is abundant experimental evidence indicating that arrangements of chromosomes in eukaryotic cell nucleus is non-random and has been evolutionary conserved in specific cell types. Moreover, the radial position of a given chromosome territory (CT) within the cell nucleus has been shown to correlate with its size and gene density. Usually it is assumed that chromosomal geometry and positioning result from the action of specific forces acting locally, such as hydrogen bonds, electrostatic, Van der Waals or hydrophobic interactions operating between nucleosomes and within their interiors. However, it is both desirable and instructive to learn to what extend organization of inter-phase chromosomes is affected by nonspecific entropic forces. In this study we report results of a coarse-grained analysis of a chromatin structure modeled by two distinct approaches. In the first method, we adhere to purely statistical analysis of chromatin packing within a chromosome territory. On the basis of the polymer theory, the chromatin fiber of diameter 30nm is approximated by a chain of spheres, each corresponding to about 30 kbp. Random positioning of the center of the domain is repeated for 1000 spherical nuclei. Configuration of the domain is determined by a random packing of a polymer (a string of identical beads) in estimated fraction of space occupied by a chromosome of a given length and mass

  14. Nuclear planetology: understanding planetary mantle and crust formation in the light of nuclear and particle physics

    Science.gov (United States)

    Roller, Goetz

    2017-04-01

    The Hertzsprung-Russell (HR) diagram is one of the most important diagrams in astronomy. In a HR diagram, the luminosity of stars and/or stellar remnants (white dwarf stars, WD's), relative to the luminosity of the sun, is plotted versus their surface temperatures (Teff). The Earth shows a striking similarity in size (radius ≈ 6.371 km) and Teff of its outer core surface (Teff ≈ 3800 K at the core-mantle-boundary) with old WD's (radius ≈ 6.300 km) like WD0346+246 (Teff ≈ 3820 K after ≈ 12.7 Ga [1]), which plot in the HR diagram close to the low-mass extension of the stellar population or main sequence. In the light of nuclear planetology [2], Earth-like planets are regarded as old, down-cooled and differentiated black dwarfs (Fe-C BLD's) after massive decompression, the most important nuclear reactions involved being 56Fe(γ,α)52Cr (etc.), possibly responsible for extreme terrestrial glaciations events ("snowball" Earth), together with (γ,n), (γ,p) and fusion reactions like 12C(α,γ)16O. The latter reaction might have caused oxidation of the planet from inside out. Nuclear planetology is a new research field, tightly constrained by a coupled 187Re-232Th-238U systematics [3-5]. By means of nuclear/quantum physics and taking the theory of relativity into account, it aims at understanding the thermal and chemical evolution of Fe-C BLD's after gravitational contraction (e.g. Mercury) or Fermi-pressure controlled collapse (e.g. Earth) events after massive decompression, leading possibly to an r-process event, towards the end of their cooling period [2]. So far and based upon 187Re-232Th-238U nuclear geochronometry, the Fe-C BLD hypothesis can successfully explain the global terrestrial MORB 232Th/238U signature [5]. Thus, it may help to elucidate the DM (depleted mantle), EMI (enriched mantle 1), EMII (enriched mantle 2) or HIMU (high U/Pb) reservoirs [6], and the 187Os/188Os isotopic dichotomy in Archean magmatic rocks and sediments [7]. Here I present a

  15. Natural formation and degradation of chloroacetic acids and volatile organochlorines in forest soil--challenges to understanding.

    Science.gov (United States)

    Laturnus, Frank; Fahimi, Isabelle; Gryndler, Milan; Hartmann, Anton; Heal, Mathew R; Matucha, Miroslav; Schöler, Heinz Friedrich; Schroll, Reiner; Svensson, Teresia

    2005-07-01

    The anthropogenic environmental emissions of chloroacetic acids and volatile organochlorines have been under scrutiny in recent years because the two compound groups are suspected to contribute to forest dieback and stratospheric ozone destruction, respectively. The two organochlorine groups are linked because the atmospheric photochemical oxidation of some volatile organochlorine compounds is one source of phytotoxic chloroacetic acids in the environment. Moreover, both groups are produced in higher amounts by natural chlorination of organic matter, e.g. by soil microorganisms, marine macroalgae and salt lake bacteria, and show similar metabolism pathways. Elucidating the origin and fate of these organohalogens is necessary to implement actions to counteract environmental problems caused by these compounds. While the anthropogenic sources of chloroacetic acids and volatile organochlorines are relatively well-known and within human control, knowledge of relevant natural processes is scarce and fragmented. This article reviews current knowledge on natural formation and degradation processes of chloroacetic acids and volatile organochlorines in forest soils, with particular emphasis on processes in the rhizosphere, and discusses future studies necessary to understand the role of forest soils in the formation and degradation of these compounds. Reviewing the present knowledge of the natural formation and degradation processes of chloroacetic acids and volatile organochlorines in forest soil has revealed gaps in knowledge regarding the actual mechanisms behind these processes. In particular, there remains insufficient quantification of reliable budgets and rates of formation and degradation of chloroacetic acids and volatile organochlorines in forest soil (both biotic and abiotic processes) to evaluate the strength of forest ecosystems regarding the emission and uptake of chloroacetic acids and volatile organochlorines, both on a regional scale and on a global scale

  16. Understanding the primary emissions and secondary formation of gaseous organic acids in the oil sands region of Alberta, Canada

    Directory of Open Access Journals (Sweden)

    J. Liggio

    2017-07-01

    Full Text Available Organic acids are known to be emitted from combustion processes and are key photochemical products of biogenic and anthropogenic precursors. Despite their multiple environmental impacts, such as on acid deposition and human–ecosystem health, little is known regarding their emission magnitudes or detailed chemical formation mechanisms. In the current work, airborne measurements of 18 gas-phase low-molecular-weight organic acids were made in the summer of 2013 over the oil sands region of Alberta, Canada, an area of intense unconventional oil extraction. The data from these measurements were used in conjunction with emission retrieval algorithms to derive the total and speciated primary organic acid emission rates, as well as secondary formation rates downwind of oil sands operations. The results of the analysis indicate that approximately 12 t day−1 of low-molecular-weight organic acids, dominated by C1–C5 acids, were emitted directly from off-road diesel vehicles within open pit mines. Although there are no specific reporting requirements for primary organic acids, the measured emissions were similar in magnitude to primary oxygenated hydrocarbon emissions, for which there are reporting thresholds, measured previously ( ≈  20 t day−1. Conversely, photochemical production of gaseous organic acids significantly exceeded the primary sources, with formation rates of up to  ≈  184 t day−1 downwind of the oil sands facilities. The formation and evolution of organic acids from a Lagrangian flight were modelled with a box model, incorporating a detailed hydrocarbon reaction mechanism extracted from the Master Chemical Mechanism (v3.3. Despite evidence of significant secondary organic acid formation, the explicit chemical box model largely underestimated their formation in the oil sands plumes, accounting for 39, 46, 26, and 23 % of the measured formic, acetic, acrylic, and propionic acids respectively and with

  17. Understanding the primary emissions and secondary formation of gaseous organic acids in the oil sands region of Alberta, Canada

    Science.gov (United States)

    Liggio, John; Moussa, Samar G.; Wentzell, Jeremy; Darlington, Andrea; Liu, Peter; Leithead, Amy; Hayden, Katherine; O'Brien, Jason; Mittermeier, Richard L.; Staebler, Ralf; Wolde, Mengistu; Li, Shao-Meng

    2017-07-01

    Organic acids are known to be emitted from combustion processes and are key photochemical products of biogenic and anthropogenic precursors. Despite their multiple environmental impacts, such as on acid deposition and human-ecosystem health, little is known regarding their emission magnitudes or detailed chemical formation mechanisms. In the current work, airborne measurements of 18 gas-phase low-molecular-weight organic acids were made in the summer of 2013 over the oil sands region of Alberta, Canada, an area of intense unconventional oil extraction. The data from these measurements were used in conjunction with emission retrieval algorithms to derive the total and speciated primary organic acid emission rates, as well as secondary formation rates downwind of oil sands operations. The results of the analysis indicate that approximately 12 t day-1 of low-molecular-weight organic acids, dominated by C1-C5 acids, were emitted directly from off-road diesel vehicles within open pit mines. Although there are no specific reporting requirements for primary organic acids, the measured emissions were similar in magnitude to primary oxygenated hydrocarbon emissions, for which there are reporting thresholds, measured previously ( ≈ 20 t day-1). Conversely, photochemical production of gaseous organic acids significantly exceeded the primary sources, with formation rates of up to ≈ 184 t day-1 downwind of the oil sands facilities. The formation and evolution of organic acids from a Lagrangian flight were modelled with a box model, incorporating a detailed hydrocarbon reaction mechanism extracted from the Master Chemical Mechanism (v3.3). Despite evidence of significant secondary organic acid formation, the explicit chemical box model largely underestimated their formation in the oil sands plumes, accounting for 39, 46, 26, and 23 % of the measured formic, acetic, acrylic, and propionic acids respectively and with little contributions from biogenic VOC precursors. The model

  18. Understanding ozone formation and the radical budget during oil sands plume transport in the Athabasca region of Alberta

    Science.gov (United States)

    Moussa, S. G.; Leithead, A.; Li, S. M.; Wang, D. K.; O'brien, J.; Mittermeier, R. L.; Gordon, M.; Staebler, R. M.; Liu, P.; Liggio, J.

    2015-12-01

    The sources of ozone and hydroxyl radicals (OH) in the Alberta oil sands (OS) region have not previously been well characterized. In the summer of 2013, airborne measurements of various volatile organic compounds (VOCs), nitrogen oxides (NOx = NO2+NO) and ozone were made in the Athabasca OS region between August 13 and September 7, 2013. Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS) and whole air samples were used to measure VOCs. A box model incorporating the Master Chemical Mechanism (MCM v3.3), was constrained by measured chemical species and meteorological parameters and used to simulate the evolution of an OS plume. In doing so, an improved understanding of the chemical factors controlling the radical budget and the evolution of ozone in oil sands plumes is achieved. Our results indicate that approximately 20% of the in-plume generated OH radicals are derived from primary sources (HCHO, O3 and HONO photolysis). The remaining OH is derived from the recycling of hydroperoxyl radical (HO2). The HO2 and alkyl peroxyl radical (RO2) chemistry leads to 35% of the ozone formation in the plume, while the main sink for ozone in the plume was via reactions with alkenes (anthropogenic and biogenic). The results of this work will help to characterize ozone formation and the factors influencing its atmospheric fate in the oil sands region.

  19. On the Magnitude and Orientation of Stress during Shock Metamorphism: Understanding Peak Ring Formation by Combining Observations and Models.

    Science.gov (United States)

    Rae, A.; Poelchau, M.; Collins, G. S.; Timms, N.; Cavosie, A. J.; Lofi, J.; Salge, T.; Riller, U. P.; Ferrière, L.; Grieve, R. A. F.; Osinski, G.; Morgan, J. V.; Expedition 364 Science Party, I. I.

    2017-12-01

    Shock metamorphism occurs during the earliest moments after impact. The magnitude and orientation of shock leaves recordable signatures in rocks, which spatially vary across an impact structure. Consequently, observations of shock metamorphism can be used to understand deformation and its history within a shock wave, and to examine subsequent deformation during crater modification. IODP-ICDP Expedition 364 recovered nearly 600 m of shocked target rocks from the peak ring of the Chicxulub Crater. Samples from the expedition were used to measure the magnitude and orientation of shock in peak ring materials, and to determine the mechanism of peak-ring emplacement. Here, we present the results of petrographic analyses of the shocked granitic target rocks of the Chicxulub peak ring; using universal-stage optical microscopy, back-scattered electron images, and electron back-scatter diffraction. Deformation microstructures in quartz include planar deformation features (PDFs), feather features (FFs), which are unique to shock conditions, as well as planar fractures and crystal-plastic deformation bands. The assemblage of PDFs in quartz suggest that the peak-ring rocks experienced shock pressures of 15 GPa throughout the recovered drill core, and that the orientation of FFs are consistent with the present-day orientation of the maximum principal stress direction during shock is close to vertical. Numerical impact simulations of the impact event were run to determine the magnitude and orientation of principal stresses during shock and track those orientations throughout crater formation. Our results are remarkably consistent with the geological data, and accurately predict both the shock-pressure magnitudes, and the final near-vertical orientation of the direction of maximum principal stress in the shock wave. Furthermore, analysis of the state of stress throughout the impact event can be used to constrain the timing of fracture and fault orientations observed in the core

  20. Insights in understanding aggregate formation and dissociation in cation exchange chromatography for a structurally unstable Fc-fusion protein.

    Science.gov (United States)

    Chen, Zhiqiang; Huang, Chao; Chennamsetty, Naresh; Xu, Xuankuo; Li, Zheng Jian

    2016-08-19

    surface properties and charged ligand type. Experimental data was correlated semi-quantitatively with theoretical protein charge and hydrophobicity calculations using homology modeling within the BIOVIA Discovery Studio software. Finally, an arginine-sulphopropyl (Arg-SP) agarose resin immobilized with multi-functional ligands was prepared to verify the proposed hypothesis and to eliminate the aggregate formation. The findings of this work provide general insights in understanding aggregate formation and dissociation for structurally unstable proteins in the CEX step. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. A short review of our current understanding of the development of ring faults during collapse caldera formation

    Directory of Open Access Journals (Sweden)

    Adelina eGeyer

    2014-09-01

    Full Text Available The term collapse caldera refers to those volcanic depressions resulting from the sinking of the chamber roof due to the rapid withdrawal of magma during the course of an eruption. During the last three decades, collapse caldera dynamics has been the focus of attention of numerous, theoretical, numerical and experimental studies. Nonetheless, even if there is a tendency to go for a general and comprehensive caldera dynamics model, some key aspects remain unclear, controversial or completely unsolved. This is the case of ring fault nucleation points and propagation and dip direction. Since direct information on calderas’ deeper structure comes mainly from partially eroded calderas or few witnessed collapses, ring faults layout at depth remains still uncertain. This has generated a strong debate over the detailed internal fault and fracture configuration of a caldera collapse and, in more detail, how ring faults initiate and propagate. We offer here a very short description of the main results obtained by those analogue and theoretical/mathematical models applied to the study of collapse caldera formation. We place special attention on those observations related to the nucleation and propagation of the collapse-controlling ring faults. This summary is relevant to understand the current state-of-the-art of this topic and it should be taken under consideration in future works dealing with collapse caldera dynamics.

  2. Understanding the Formation of the Self-Assembly of Colloidal Copper Nanoparticles by Surfactant: A Molecular Velcro

    Directory of Open Access Journals (Sweden)

    Raquel Kely Bortoleto-Bugs

    2013-01-01

    Full Text Available Self-assembly procedure is employed to synthesize colloidal copper nanoparticles (ccNPs with cationic surfactant in an environmentally friendly method. Scanning electron microscopy images provide a clear view of the ccNPs formed having an approximate size of 15 nm. The X-ray diffraction reveals that the ccNPs have the two types of copper oxide as well as the metallic copper. The new procedure shows that the cationic surfactant CTAB plays an important role in the understanding and development of self-assembly. There is a strong relationship between the ccNPs formation with the critical micelle concentration of the CTAB which influences both shape and size. The outcomes allowed the development of a molecular model for the ccNPs synthesis showing that the CTAB monomer on the surface has the function of a molecular velcro making the linkage of ccNPs to form an agglomerate with size around 600 nm. Finally, with the emerging new technologies, the synthesis of copper oxide takes a new perspective for their applicability in diverse integrated areas such as the flexible electronics and energy.

  3. Coupling an aerosol box model with one-dimensional flow: a tool for understanding observations of new particle formation events

    OpenAIRE

    Kivekäs, N.; Carpman, J.; Roldin, P.; Leppä, J.; O'Connor, E. J.; Kristensson, A.; Asmi, E.

    2016-01-01

    Field observations of new particle formation and the subsequent particle growth are typically only possible at a fixed measurement location, and hence do not follow the temporal evolution of an air parcel in a Lagrangian sense. Standard analysis for determining formation and growth rates requires that the time-dependent formation rate and growth rate of the particles are spatially invariant; air parcel advection means that the observed temporal evolution of the particle size distribution at a...

  4. Coupling an aerosol box model with one-dimensional flow: a tool for understanding observations of new particle formation events

    Directory of Open Access Journals (Sweden)

    Niku Kivekäs

    2016-04-01

    Full Text Available Field observations of new particle formation and the subsequent particle growth are typically only possible at a fixed measurement location, and hence do not follow the temporal evolution of an air parcel in a Lagrangian sense. Standard analysis for determining formation and growth rates requires that the time-dependent formation rate and growth rate of the particles are spatially invariant; air parcel advection means that the observed temporal evolution of the particle size distribution at a fixed measurement location may not represent the true evolution if there are spatial variations in the formation and growth rates. Here we present a zero-dimensional aerosol box model coupled with one-dimensional atmospheric flow to describe the impact of advection on the evolution of simulated new particle formation events. Wind speed, particle formation rates and growth rates are input parameters that can vary as a function of time and location, using wind speed to connect location to time. The output simulates measurements at a fixed location; formation and growth rates of the particle mode can then be calculated from the simulated observations at a stationary point for different scenarios and be compared with the ‘true’ input parameters. Hence, we can investigate how spatial variations in the formation and growth rates of new particles would appear in observations of particle number size distributions at a fixed measurement site. We show that the particle size distribution and growth rate at a fixed location is dependent on the formation and growth parameters upwind, even if local conditions do not vary. We also show that different input parameters used may result in very similar simulated measurements. Erroneous interpretation of observations in terms of particle formation and growth rates, and the time span and areal extent of new particle formation, is possible if the spatial effects are not accounted for.

  5. Using 238U/235U ratios to understand the formation and oxidation of reduced uranium solids in naturally reduced zones

    Science.gov (United States)

    Jemison, N.; Johnson, T. M.; Druhan, J. L.; Davis, J. A.

    2016-12-01

    Uranium occurs in groundwater primarily as soluble and mobile U(VI), which can be reduced to immobile U(IV), often observed in sediments as uraninite. Numerous U(VI)-contaminated sites, such as the DOE field site in Rifle, CO, contain naturally reduced zones (NRZ's) that have relatively high concentrations of organic matter. Reduction of heavy metals occurs within NRZ's, producing elevated concentrations of iron sulfides and U(IV). Slow, natural oxidation of U(IV) from NRZ's may prolong U(VI) contamination of groundwater. The reduction of U(VI) produces U(IV) with a higher 238U/235U ratio. Samples from two NRZ sediment cores recovered from the Rifle site revealed that the outer fringes of the NRZ contain U(IV) with a high 238U/235U ratio, while lower values are observed in the center . We suggest that as aqueous U(VI) was reduced in the NRZ, it was driven to lower 238U/235U values, such that U(IV) formed in the core of the NRZ reflects a lower 238U/235U. Two oxidation experiments were conducted by injecting groundwater containing between 14.9 and 21.2 mg/L dissolved O2 as an oxidant into the NRZ. The oxidation of U(IV) from this NRZ increased aqueous U(VI) concentrations and caused a shift to higher 238U/235U in groundwater as U(IV) was oxidized primarily on the outer fringes of the NRZ. In total these observations suggest that the stability of solid phase uranium is governed by coupled reaction and transport processes. To better understand various reactive transport scenarios we developed a model for the formation and oxidation of NRZ's utilizing the reactive transport software CrunchTope. These simulations suggest that the development of isotopically heterogeneous U(IV) within NRZ's is largely controlled by permeability of the NRZ and the U(VI) reduction rate. Oxidation of U(IV) from the NRZ's is constrained by the oxidation rate of U(IV) as well as iron sulfides, which can prevent oxidation of U(IV) by scavenging dissolved oxygen.

  6. The effectiveness of formative assessment with understanding by design (UbD) stages in forming habits of mind in prospective teachers

    Science.gov (United States)

    Gloria, R. Y.; Sudarmin, S.; Wiyanto; Indriyanti, D. R.

    2018-03-01

    Habits of mind are intelligent thinking dispositions that every individual needs to have, and it needs an effort to form them as expected. A behavior can be formed by continuous practice; therefore the student's habits of mind can also be formed and trained. One effort that can be used to encourage the formation of habits of mind is a formative assessment strategy with the stages of UbD (Understanding by Design), and a study needs to be done to prove it. This study aims to determine the contribution of formative assessment to the value of habits of mind owned by prospective teachers. The method used is a quantitative method with a quasi-experimental design. To determine the effectiveness of formative assessment with Ubd stages on the formation of habits of mind, correlation test and regression analysis were conducted in the formative assessment questionnaire consisting of three components, i.e. feed back, peer assessment and self assessment, and habits of mind. The result of the research shows that from the three components of Formative Assessment, only Feedback component does not show correlation to students’ habits of mind (r = 0.323). While peer assessment component (r = 0. 732) and self assessment component (r = 0.625), both indicate correlation. From the regression test the overall component of the formative assessment contributed to the habits of mind at 57.1%. From the result of the research, it can be concluded that the formative assessment with Ubd stages is effective and contributes in forming the student's habits of mind; the formative assessment components that contributed the most are the peer assessment and self assessment. The greatest contribution goes to the Thinking interdependently category.

  7. Understanding the formation process of the liquid slug in a hilly-terrain wet natural gas pipeline

    DEFF Research Database (Denmark)

    Yang, Yan; Li, Jingbo; Wang, Shuli

    2017-01-01

    condition on the liquid slug formation is discussed including pipe diameter, inclination angle, gas superficial velocity and liquid holdup. The results show that the pipe is blocked by the liquid slug at the moment of slug formed. The pipe pressure suddenly increases, and then decreases gradually...... in the process of liquid slug formation and motion. The pipe pressure drop and liquid holdup decrease along with the increasing inclination angle of ascending pipe. On the contrary, they rise with the increase of the inclination angle of descending pipe. Higher gas superficial velocity and liquid holdup result...

  8. Formation of colloids from introduced materials in the post-emplacement environment: A report on the state of understanding

    International Nuclear Information System (INIS)

    Meike, A.; Wittwer, C.

    1993-09-01

    This literature review examines potential sources of colloids and enhanced adsorption that may stem from materials introduced into a repository setting, with a view towards prioritizing future studies. Three major sources of colloids are reviewed: metals, cements, and organics. Know chemical influences on colloid formation and mechanisms by which introduced materials may become involved are considered with respect to gradients, chemical species, pH, time, temperature, radiolysis, redox state, and microbial activity. Areas that have not been addressed but may have significant consequences in a repository setting are identified

  9. VERTEBRATES OF THE MARÍLIA FORMATION (LATE MAASTRICHTIAN FROM THE PEIRÓPOLIS PALEONTOLOGICAL SITE: TOWARD A BETTER UNDERSTANDING

    Directory of Open Access Journals (Sweden)

    A. Candeiro Carlos Roberto

    2009-07-01

    Full Text Available The Peirópolis paleontological site (Late Cretaceous, Maastrichtian in Minas Gerais State, Brazil yielded an important assemblage of fossil vertebrates. The typical occurrence of South American widespread taxa in Peirópolis is important for correlation between the Brazilian Bauru Basin and Argentinean Late Cretaceous basins. The fishes, turtles, anuran, crocodilians and dinosaurs known from Peirópolis (Marília Formation resemble the Patagonian latest Late Cretaceous vertebrate faunas but lacks ornithischian dinosaurs.

  10. The effect of different cardiovascular risk presentation formats on intentions, understanding and emotional affect: a randomised controlled trial using a web-based risk formatter (protocol

    Directory of Open Access Journals (Sweden)

    Newcombe Robert

    2010-07-01

    Full Text Available Abstract Background The future risk of heart disease can be predicted with increasing precision. However, more research is needed into how this risk is conveyed and presented. The aim of this study is to compare the effects of presenting cardiovascular risk in different formats on individuals' intention to change behaviour to reduce risk, understanding of risk information and emotional affect. Methods/design A randomised controlled trial comprising four arms, with a between subjects design will be performed. There will be two intervention groups and two control groups. The first control comprises a pre-intervention questionnaire and presents risk in a bar graph format. The second control presents risk in a bar graph format without pre-intervention questionnaire. These two control groups are to account for the potential Hawthorne effect of thinking about cardiovascular risk before viewing actual risk. The two intervention groups comprise presenting risk in either a pictogram or metonym format (image depicting seriousness of having a myocardial infarction. 800 individuals' aged between 45 and 64 years, who have not been previously diagnosed with heart disease and have access to a computer with internet, will be given a link to a website comprising a risk calculator and electronic questionnaires. 10-year risk of having a coronary heart disease event will be assessed and presented in one of the three formats. A post-intervention questionnaire will be completed after viewing the risk format. Main outcome measures are (i intention to change behaviour, (ii understanding of risk information, (iii emotional affect and (iv worry about future heart disease. Secondary outcomes are the sub-components of the theory of planned behaviour: attitudes, perceived behavioural control and subjective norms. Discussion Having reviewed the literature, we are not aware of any other studies which have used the assessment of actual risk, in a trial to compare different

  11. Understanding the wetting properties of nanostructured selenium coatings: the role of nanostructured surface roughness and air-pocket formation

    Directory of Open Access Journals (Sweden)

    Tran PA

    2013-05-01

    Full Text Available Phong A Tran,1,2 Thomas J Webster31Department of Chemical and Biomolecular Engineering, University of Melbourne, Melbourne, VIC, Australia; 2The Particulate Fluid Processing Centre, University of Melbourne, Melbourne, VIC, Australia; 3Department of Chemical Engineering and Program in Bioengineering, Northeastern University, Boston, MA, USAAbstract: Wetting properties of biomaterials, in particular nanomaterials, play an important role, as these influence interactions with biological elements, such as proteins, bacteria, and cells. In this study, the wetting phenomenon of titanium substrates coated with selenium nanoparticles was studied using experimental and mathematical modeling tools. Importantly, these selenium-coated titanium substrates were previously reported to increase select protein adsorption (such as vitronectin and fibronectin, to decrease bacteria growth, and increase bone cell growth. Increased selenium nanoparticle coating density resulted in higher contact angles but remained within the hydrophilic regime. This trend was found in disagreement with the Wenzel model, which is widely used to understand the wetting properties of rough surfaces. The trend also did not fit well with the Cassie–Baxter model, which was developed to understand the wetting properties of composite surfaces. A modified wetting model was thus proposed in this study, to understand the contributing factors of material properties to the hydrophilicity/hydrophobicity of these nanostructured selenium-coated surfaces. The analysis and model created in this study can be useful in designing and/or understanding the wetting behavior of numerous biomedical materials and in turn, biological events (such as protein adsorption as well as bacteria and mammalian cell functions.Keywords: hydrophilicity, hydrophobicity, Wenzel model, Cassie–Baxter model, free energy, implant material, proteins, cells, bacteria

  12. Understanding the acquisition and regulation mechanisms of the water chemistry in a clay formation: the CEC/ANDRA Archimede-argile project

    International Nuclear Information System (INIS)

    Merceron, T.; Mossmann, J.R.; Neerdael, B.; Canniere, P. de; Beaucaire, C.; Toulhoat, P.; Daumas, S.; Bianchi, A.; Christen, R.

    1993-01-01

    Clay formations are candidate host environments to high level radioactive waste repository. The radioelements could be partially released from the waste into the host geological formation after a very long time. Understanding behaviour of the natural chemical species is considered as a fundamental prerequisite before the disturbed system will be studied. Additional laboratory studies are also essential in order to forecast, by analogy, the behaviour of radioelements released from the radioactive waste repository. The ARCHIMEDE-ARGILE project has two main goals. The first is to gain an understanding of the mechanisms of acquisition and regulation of the water chemistry in a clay environment. This step is essential to predict both the behaviour and the migration in solution of artificial elements which are initially absent in the clay formation. The second is to test and validate in clay the measured physico chemical parameters which are the basis for the geochemical modelling of the behaviour of the natural and artificial radioelements. The paper presents the main results previously obtained on granitic waters and the research strategy established for the ARCHIMEDE project. (authors). 2 figs., 2 refs

  13. HabEat: Understanding critical periods and critical factors of the formation and of the modification of food habits

    OpenAIRE

    Nicklaus, Sophie; Issanchou, Sylvie

    2011-01-01

    Introduction: Diets of young children in many European countries are not ideal (too many lipids; not enough fruit and vegetables). Early nutrition may have an impact on health in later life (diabetes, obesity, heart problems) and the first two years of life are of crucial importance in the acquisition of food habits. The HabEat project aims at understanding better of how food habits are formed and can be changed, in infants and children (< 5 years). Methods: With 11 beneficiaries from 6 Euro...

  14. Cationic amino acids specific biomimetic silicification in ionic liquid: a quest to understand the formation of 3-D structures in diatoms.

    Directory of Open Access Journals (Sweden)

    Rajesh Ramanathan

    Full Text Available The intricate, hierarchical, highly reproducible, and exquisite biosilica structures formed by diatoms have generated great interest to understand biosilicification processes in nature. This curiosity is driven by the quest of researchers to understand nature's complexity, which might enable reproducing these elegant natural diatomaceous structures in our laboratories via biomimetics, which is currently beyond the capabilities of material scientists. To this end, significant understanding of the biomolecules involved in biosilicification has been gained, wherein cationic peptides and proteins are found to play a key role in the formation of these exquisite structures. Although biochemical factors responsible for silica formation in diatoms have been studied for decades, the challenge to mimic biosilica structures similar to those synthesized by diatoms in their natural habitats has not hitherto been successful. This has led to an increasingly interesting debate that physico-chemical environment surrounding diatoms might play an additional critical role towards the control of diatom morphologies. The current study demonstrates this proof of concept by using cationic amino acids as catalyst/template/scaffold towards attaining diatom-like silica morphologies under biomimetic conditions in ionic liquids.

  15. Applying a new understanding of supergene REE deposit formation to global exploration initiatives for environmentally sustainable resources

    Science.gov (United States)

    Hardy, Liam; Smith, Martin; Hood, Leo; Heller, Shaun; Faltyn, Rowan; Blum, Astrid; Bamberger, Axel

    2017-04-01

    Two new models have recently been proposed for the formation of REE ion-adsorption deposits and it is likely that they are both active in their related study profiles described in the Ambohimirahavavy Complex in Madagascar (Marquis et al, 2016) and the Serra de Monchique (SDM) complex in Portugal (Hardy et al, 2016). These are two separate environments presenting two different soil systems in terms of flora, protolith and structure. In the latosol profiles of SDM the natural sweating cycle of eucalyptus trees is proposed as the main geochemical cycling control for some 40% of Fe and 30% of Y, which have been observed migrating up and down profile seasonally between upper horizons and the rooting depths of these intensively farmed trees. If, through their natural cycle, eucalyptus trees in SDM are capable of concentrating depleted protolithic Y contents of 4-10ppm to some 140-160ppm in their enriched 150-200cm deep E horizons in only the 40 years since they were introduced to the region (Jenkins, 1979), then what potential deposits and concentrations may lay underneath older plantations across Brazil, Chile, China and most importantly, Australia, where these trees naturally cover some 16% of the entire continent. Eucalyptus is mostly farmed as pulp for paper mills and has lost its market value with the demand for paper decreasing, as the demand for REEs increases, ironically driven by the demand for the accessible technology to replace paper (EPA, 2012). Not only might there be great resources below these forests, but the removal of the aggressive intrusive species would be welcomed across Southern Europe and South America where they have limited market value and have destroyed local ecosystems and water supplies (Brito, 1999), where local people are actively seeking an alternative use of their lands. References: Brito, J. G. (1999). Management strategies for conservation of the lizard Lacerta schreiberi in Portugal. Biological conservation, 311-319. EPA. (2012

  16. Nanoparticle Surface Specific Adsorption of Zein and Its Self-assembled Behavior of Nanocubes Formation in Relation to On-Off SERS: Understanding Morphology Control of Protein Aggregates.

    Science.gov (United States)

    Navdeep; Banipal, Tarlok Singh; Kaur, Gurinder; Bakshi, Mandeep Singh

    2016-01-27

    Zein, an industrially important protein, is characterized in terms of its food and pharmaceutical coating applications by using surface enhanced Raman spectroscopy (SERS) on Au, Ag, and PbS nanoparticles (NPs). Its specific surface adsorption behavior on Ag NPs produced self-assembled zein nanocubes which demonstrated on and off SERS activity. Both SERS characterization as well as nanocube formation of zein helped us to understand the complex protein aggregation behavior in shape controlled morphologies, a process with significant ramifications in protein crystallization to achieve ordered morphologies. Interestingly, nanocube formation was promoted in the presence of Ag rather than Au or PbS NPs under in situ synthesis and discussed in terms of specific adsorption. Zein fingerprinting was much more clear and enhanced on Au surface in comparison to Ag while PbS did not demonstrate SERS due to its semiconducting nature.

  17. Hands in medicine: understanding the impact of competency-based education on the formation of medical students’ identities in the United States

    Directory of Open Access Journals (Sweden)

    Catherine Gonsalves

    2016-08-01

    Full Text Available Purpose There have been critiques that competency training, which defines the roles of a physician by simple, discrete tasks or measurable competencies, can cause students to compartmentalize and focus mainly on being assessed without understanding how the interconnected competencies help shape their role as future physicians. Losing the meaning and interaction of competencies can result in a focus on ‘doing the work of a physician’ rather than identity formation and ‘being a physician.’ This study aims to understand how competency-based education impacts the development of a medical student’s identity. Methods Three ceramic models representing three core competencies ‘medical knowledge,’ ‘patient care,’ and ‘professionalism’ were used as sensitizing objects, while medical students reflected on the impact of competency-based education on identity formation. Qualitative analysis was used to identify common themes. Results Students across all four years of medical school related to the ‘professionalism’ competency domain (50%. They reflected that ‘being an empathetic physician’ was the most important competency. Overall, students agreed that competency-based education played a significant role in the formation of their identity. Some students reflected on having difficulty in visualizing the interconnectedness between competencies, while others did not. Students reported that the assessment structure deemphasized ‘professionalism’ as a competency. Conclusion Students perceive ‘professionalism’ as a competency that impacts their identity formation in the social role of ‘being a doctor,’ albeit a competency they are less likely to be assessed on. High-stakes exams, including the United States Medical Licensing Exam clinical skills exam, promote this perception.

  18. The understanding of the formation of valleys and its implication on site characterization: Moredalen and Pukedalen, south-eastern Sweden

    International Nuclear Information System (INIS)

    Tiren, Sven A.; Waenstedt, Stefan; Straeng, Thomas

    2010-11-01

    In south-eastern Sweden, there are a number of over-deepened narrow valleys, more than 20 m deep, formed in Precambrian bedrock located above the highest post-glacial shoreline. Canyon-like valleys, called 'kursu' or kursu valleys, are generally interpreted to be formed by glaciofluvial erosion. An example of such a valley is Moredalen, a canyon in the Fennoscandian Shield, which has an implication on site selection for radioactive waste disposal. There are also more open over-deepened valleys along which sub-glacial flow has occurred, e.g. Pukedalen. The main part of this paper discusses a combined geological and geophysical investigation of Moredalen, with the aim to investigate possible reasons for the formation of such an unusual feature formed in acid vulcanite and foliated tonalitic to granodioritic rocks. Moredalen is a marked, approximately 7 km long, E-W striking valley that cuts through a plateau (c. 140 m a.s.l.), and an elevated block of the sub-Cambrian peneplain. Glaciofluvial sediments can be found up-streams where the canyon widens to the west. Just east of the valley is a larger delta deposited at the highest post-glacial shoreline (c. 105 m a.s.l). Further east of, and in line with the Moredalen valley there is an esker. Rock debris in the valley is angular. Pukedalen is a northwest-southeast trending valley incised in massive granite. The valley is in its northern parts relatively open and becomes narrow in its south-eastern part having partly a vertical south-western wall. Rock surfaces are smooth along the valley and rock debris in the valley consists generally of rounded blocks. In line with Pukedalen, on both sides at great distances though, there are eskers. Geomorphological features of this kind indicate certain characteristics of the bedrock that need to be considered during safety analysis of repositories for nuclear waste. The distinct weakness zones along which the kursu-valleys are formed create prominent transport paths for

  19. Tectonomagmatic evolution of the terrestrial planets: importance for understanding of processes of their formation and subsequent development

    Science.gov (United States)

    Sharkov, E.; Bogatikov, O.

    2009-04-01

    Our knowledge about formation and evolution of the terrestrial planets (the Earth, Venus, Mars, Mercury and, possibly, the Moon) based on different physical and geochemical speculations and models. The main disadvantage of such hypotheses is their abstract character and ignoring any data on tectonomagmatic evolution of those planets. At the same time, just this type of data provide an important information, which is necessary for elaborating of a present-day theory of their formation and evolution. The Earth has been much better studied compared to the other planets, therefore we will discuss the main questions of planetary tectonomagmatic evolution using the Earth as example plus involve other data on the Moon and the terrestrial planets. Two dominating hypotheses about composition of the primordial Earth's crust exist now: (1) traditional implies that the primordial crust had basic composition, whereas the sialic crust resulted from a geosyncline process or, in modern terms, from processes at convergent plate margins, and (2) primordial crust was sialic; the plate tectonic mechanisms started in the Middle Paleoproterozoic and resulted in oceanic spreading and formation of the secondary oceanic crust. Both models require a global melting of a primary chondritic material to form the primordial crust. The final result depends on the degree of melt differentiation during solidification of a magmatic ocean. Such a solidification, due to differences between adiabatic and melting-points gradients had to proceed in bottom-top direction (Jeffries, 1929) and resulted in accumulation of low-temperature derivates in the primordial crust. Geological data, namely granite-dominated Archean crust, and results of studying of detrital zircon from Australia supports the primordial-sialic crust hypothesis. The Moon which is four times smaller than Earth has a basic primordial crust. Such a difference can be explained by different depths of their magmatic oceans. The Early

  20. Understanding the formation of the Ontong Java Plateau through joint ambient noise earthquake tomography and laboratory modeling

    Science.gov (United States)

    Covellone, B. M.; Szwaja, S.; Savage, B. K.; Shen, Y.; Kincaid, C. R.

    2013-12-01

    Current knowledge of the Ontong Java Plateau (OJP) comes from a broad range of research disciplines. Despite decades of work, numerous hypotheses on the origin of the OJP do not fully address all of the geophysical and geochemical observations. A more complete image of the current lower crust and upper mantle seismic structure beneath the plateau will provide a link between the plateau's 120 Ma complex history and it's formation. We investigate the anomalous wave speed structure underlying the OJP using an iterative, full-waveform, joint ambient noise and earthquake tomography approach. A 3-dimensional wave speed model is determined from ambient noise data at periods between 25 and 200 seconds. Data from over 100 earthquakes, recorded between 1990 and 2012, are then added to the inversion to improve data coverage and model resolution. The combination of datasets allows us to best exploit the limited station distribution in the Pacific, resulting in resolution better than 5-degrees beneath the plateau and extending to depths greater than 350 km. To improve our sense of expected deformation patterns for sub-plateau mantle through geologic time, a set of laboratory models were run where OJP residuum viscosity is changed relative to the ambient fluid. Models focus on the interaction between OJP residuum and the rollback-driven flow associated with passage of the Tonga subduction system to the south. Model results show dramatic thinning and extraction of the southern portion of sub-OJP fluid due to subduction induced torroidal flows. Significant distortion of the sub-OJP material over roughly the last 40 Ma is predicted in cases where residuum is either stronger or weaker than ambient fluid. The results of this work confirm an anomalously slow mantle beneath the OJP extending to depths greater than 300 km and provide high-resolution images constraining the magnitude and dimensions of wave speed anomalies that can be used to determine thermal and compositional variations

  1. Formation of complexes between hematite nanoparticles and a non-conventional galactomannan gum. Toward a better understanding on interaction processes.

    Science.gov (United States)

    Busch, Verónica M; Loosli, Fréderic; Santagapita, Patricio R; Buera, M Pilar; Stoll, Serge

    2015-11-01

    The physicochemical characteristics of hematite nanoparticles related to their size, surface area and reactivity make them useful for many applications, as well as suitable models to study aggregation kinetics. For several applications (such as remediation of contaminated groundwater) it is crucial to maintain the stability of hematite nanoparticle suspensions in order to assure their arrival to the target place. The use of biopolymers has been proposed as a suitable environmentally friendly option to avoid nanoparticle aggregation and assure their stability. The aim of the present work was to investigate the formation of complexes between hematite nanoparticles and a non-conventional galactomannan (vinal gum--VG) obtained from Prosopis ruscifolia in order to promote hematite nanoparticle coating with a green biopolymer. Zeta potential and size of hematite nanoparticles, VG dispersions and the stability of their mixtures were investigated, as well as the influence of the biopolymer concentration and preparation method. DLS and nanoparticle tracking analysis techniques were used for determining the size and the zeta-potential of the suspensions. VG showed a polydispersed size distribution (300-475 nm Z-average diameter, 0.65 Pdi) and a negative zeta potential (between -1 and -12 mV for pH2 and 12, respectively). The aggregation of hematite nanoparticles (3.3 mg/L) was induced by the addition of VG at lower concentrations than 2mg/L (pH5.5). On the other hand, hematite nanoparticles were stabilized at concentrations of VG higher than 2 mg/L. Several phenomena between hematite nanoparticles and VG were involved: steric effects, electrostatic interactions, charge neutralization, charge inversion and polymer bridging. The process of complexation between hematite nanoparticles and the biopolymer was strongly influenced by the preparation protocols. It was concluded that the aggregation, dispersion, and stability of hematite nanoparticles depended on biopolymer

  2. REDUCING RISK IN LOW-PERMEABILITY GAS FORMATIONS: UNDERSTANDING THE ROCK/FLUID CHARACTERISTICS OF ROCKY MOUNTAIN LARAMIDE BASINS

    Energy Technology Data Exchange (ETDEWEB)

    Ronald C. Surdam

    2003-12-29

    An anomalous velocity model was constructed for the Wind River Basin (WRB) based on {approx}2000 mi of 2-D seismic data and 175 sonic logs, for a total of 132,000 velocity/depth profiles. Ten cross sections were constructed through the model coincident with known gas fields. In each cross section, an intense, anomalously slow velocity domain coincided with the gas-productive rock/fluid interval. The anomalous velocity model: (1) Easily isolates gas-charged rock/fluid systems characterized by anomalously slow velocities and water-rich rock/fluid systems characterized by normal velocities; and (2) Delineates the regional velocity inversion surface, which is characterized by steepening of the Ro/depth gradient, a significant increase in capillary displacement pressure, a significant change in formation water composition, and acceleration of the reaction rate of smectite-to-illite diagenesis in mixed-layer clays. Gas chimneys are observed as topographic highs on the regional velocity inversion surface. Beneath the surface are significant fluid-flow compartments, which have a gas-charge in the fluid phase and are isolated from meteoric water recharge. Water-rich domains may occur within regional gas-charged compartments, but are not being recharged from the meteoric water system (i.e., trapped water). The WRB is divided into at least two regionally prominent fluid-flow compartments separated by the velocity inversion surface: a water-dominated upper compartment likely under strong meteoric water drive and a gas-charged, anomalously pressured lower compartment. Judging from cross sections, numerous gas-charged subcompartments occur within the regional compartment. Their geometries and boundaries are controlled by faults and low-permeability rocks. Commercial gas production results when a reservoir interval characterized by enhanced porosity/permeability intersects one of these gas-charged subcompartments. The rock/fluid characteristics of the Rocky Mountain Laramide

  3. Can Process Understanding Help Elucidate The Structure Of The Critical Zone? Comparing Process-Based Soil Formation Models With Digital Soil Mapping.

    Science.gov (United States)

    Vanwalleghem, T.; Román, A.; Peña, A.; Laguna, A.; Giráldez, J. V.

    2017-12-01

    There is a need for better understanding the processes influencing soil formation and the resulting distribution of soil properties in the critical zone. Soil properties can exhibit strong spatial variation, even at the small catchment scale. Especially soil carbon pools in semi-arid, mountainous areas are highly uncertain because bulk density and stoniness are very heterogeneous and rarely measured explicitly. In this study, we explore the spatial variability in key soil properties (soil carbon stocks, stoniness, bulk density and soil depth) as a function of processes shaping the critical zone (weathering, erosion, soil water fluxes and vegetation patterns). We also compare the potential of traditional digital soil mapping versus a mechanistic soil formation model (MILESD) for predicting these key soil properties. Soil core samples were collected from 67 locations at 6 depths. Total soil organic carbon stocks were 4.38 kg m-2. Solar radiation proved to be the key variable controlling soil carbon distribution. Stone content was mostly controlled by slope, indicating the importance of erosion. Spatial distribution of bulk density was found to be highly random. Finally, total carbon stocks were predicted using a random forest model whose main covariates were solar radiation and NDVI. The model predicts carbon stocks that are double as high on north versus south-facing slopes. However, validation showed that these covariates only explained 25% of the variation in the dataset. Apparently, present-day landscape and vegetation properties are not sufficient to fully explain variability in the soil carbon stocks in this complex terrain under natural vegetation. This is attributed to a high spatial variability in bulk density and stoniness, key variables controlling carbon stocks. Similar results were obtained with the mechanistic soil formation model MILESD, suggesting that more complex models might be needed to further explore this high spatial variability.

  4. A method for the production of large volumes of WAF and CEWAF for dosing mesocosms to understand marine oil snow formation.

    Science.gov (United States)

    Wade, Terry L; Morales-McDevitt, Maya; Bera, Gopal; Shi, Dawai; Sweet, Stephen; Wang, Binbin; Gold-Bouchot, Gerado; Quigg, Antonietta; Knap, Anthony H

    2017-10-01

    Marine oil snow (MOS) formation is a mechanism to transport oil from the ocean surface to sediments. We describe here the use of 110L mesocosms designed to mimic oceanic parameters during an oil spill including the use of chemical dispersants in order to understand the processes controlling MOS formation. These experiments were not designed to be toxicity tests but rather to illustrate mechanisms. This paper focuses on the development of protocols needed to conduct experiments under environmentally relevant conditions to examine marine snow and MOS. The experiments required the production of over 500 liters of water accommodated fraction (WAF), chemically enhanced water accommodated fraction of oil (CEWAF) as well as diluted CEWAF (DCEWAF). A redesigned baffled (170 L) recirculating tank (BRT) system was used. Two mesocosm experiments (M1 and M2) were run for several days each. In both M1 and M2, marine snow and MOS was formed in controls and all treatments respectively. Estimated oil equivalent (EOE) concentrations of CEWAF were in the high range of concentrations reported during spills and field tests, while WAF and DCEWAF concentrations were within the range of concentrations reported during oil spills. EOE decreased rapidly within days in agreement with historic data and experiments.

  5. Understanding Litter Input Controls on Soil Organic Matter Turnover and Formation are Essential for Improving Carbon-Climate Feedback Predictions for Arctic, Tundra Ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Wallenstein, Matthew [Colorado State Univ., Fort Collins, CO (United States)

    2017-12-05

    The Arctic region stored vast amounts of carbon (C) in soils over thousands of years because decomposition has been limited by cold, wet conditions. Arctic soils now contain roughly as much C that is contained in all other soils across the globe combined. However, climate warming could unlock this oil C as decomposition accelerates and permafrost thaws. In addition to temperature-driven acceleration of decomposition, several additional processes could either counteract or augment warming-induced SOM losses. For example, increased plant growth under a warmer climate will increase organic matter inputs to soils, which could fuel further soil decomposition by microbes, but will also increase the production of new SOM. Whether Arctic ecosystems store or release carbon in the future depends in part on the balance between these two counteracting processes. By differentiating SOM decomposition and formation and understanding the drivers of these processes, we will better understand how these systems function. We did not find evidence of priming under current conditions, defined as an increase in the decomposition of native SOM stocks. This suggests that decomposition is unlikely to be further accelerated through this mechanism. We did find that decomposition of native SOM did occur when nitrogen was added to these soils, suggesting that nitrogen limits decomposition in these systems. Our results highlight the resilience and extraordinary C storage capacity of these soils, and suggest shrub expansion may partially mitigate C losses from decomposition of old SOM as Arctic soils warm.

  6. Biophysical and biochemical strategies to understand membrane binding and pore formation by sticholysins, pore-forming proteins from a sea anemone.

    Science.gov (United States)

    Alvarez, Carlos; Ros, Uris; Valle, Aisel; Pedrera, Lohans; Soto, Carmen; Hervis, Yadira P; Cabezas, Sheila; Valiente, Pedro A; Pazos, Fabiola; Lanio, Maria E

    2017-10-01

    Actinoporins constitute a unique class of pore-forming toxins found in sea anemones that are able to bind and oligomerize in membranes, leading to cell swelling, impairment of ionic gradients and, eventually, to cell death. In this review we summarize the knowledge generated from the combination of biochemical and biophysical approaches to the study of sticholysins I and II (Sts, StI/II), two actinoporins largely characterized by the Center of Protein Studies at the University of Havana during the last 20 years. These approaches include strategies for understanding the toxin structure-function relationship, the protein-membrane association process leading to pore formation and the interaction of toxin with cells. The rational combination of experimental and theoretical tools have allowed unraveling, at least partially, of the complex mechanisms involved in toxin-membrane interaction and of the molecular pathways triggered upon this interaction. The study of actinoporins is important not only to gain an understanding of their biological roles in anemone venom but also to investigate basic molecular mechanisms of protein insertion into membranes, protein-lipid interactions and the modulation of protein conformation by lipid binding. A deeper knowledge of the basic molecular mechanisms involved in Sts-cell interaction, as described in this review, will support the current investigations conducted by our group which focus on the design of immunotoxins against tumor cells and antigen-releasing systems to cell cytosol as Sts-based vaccine platforms.

  7. The effects of infographics and several quantitative versus qualitative formats for cardiovascular disease risk, including heart age, on people's risk understanding.

    Science.gov (United States)

    Damman, Olga C; Vonk, Suzanne I; van den Haak, Maaike J; van Hooijdonk, Charlotte M J; Timmermans, Danielle R M

    2018-03-11

    To study how comprehension of cardiovascular disease (CVD) risk is influenced by: (1) infographics about qualitative risk information, with/without risk numbers; (2) which qualitative risk dimension is emphasized; (3) heart age vs. traditional risk format. For aim 1, a 2 (infographics versus text) x 2 (risk number versus no risk number) between-subjects design was used. For aim 2, three pieces of information were tested within-subjects. Aim 3 used a simple comparison group. Participants (45-65 yrs old) were recruited through an online access panel; low educated people were oversampled. They received hypothetical risk information (20%/61yrs). Primary outcomes: recall, risk appraisals, subjective/objective risk comprehension. behavioral intentions, information evaluations. Infographics of qualitative risk dimensions negatively affected recall, subjective risk comprehension and information evaluations. No effect of type of risk dimension was found on risk perception. Heart age influenced recall, comprehension, evaluations and affective risk appraisals. Infographics of hypothetical CVD risk information had detrimental effects on measures related to risk perception/comprehension, but effects were mainly seen in undereducated participants. Heart age influenced perceptions/comprehension of hypothetical risk in a way that seemed to support understanding. Heart age seems a fruitful risk communication approach in disease risk calculators. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. The Center for Intercultural Formation, Cuernavaca, Mexico, its reports (1962-1967 and Illich’s critical understanding of mission in Latin America

    Directory of Open Access Journals (Sweden)

    Bruno-Jofré, Rosa

    2014-12-01

    Full Text Available This paper examines the Reports of the Center for Intercultural Formation (CIF, which were produced in Cuernavaca, Mexico, between 1962-1967 by the Centro de Investigaciones Culturales (Center for Cultural Research (CIC, and supported since 1963 by the Centro Intercultural de Documentación (Center for Intercultural Documentation (CIDOC (an offshoot of CIC. The network is placed within the historical conjuncture of the early 1960s and the alignment of the Vatican with the Alliance for Progress and its anti-communist developmentalist community projects. The core of the paper centers in the ‘illocutionary force’ (Quentin Skinner behind Illich’s responses to John XXIII’s call to congregations and lay Catholics for a renewed mission in Latin America. It addresses Illich’s resignification of the understanding of mission and missioner rooted in the Gospel, the notion of incarnation in the culture rather than missioners being agents of their culture, and missionary “poverty” as a virtue of the community worker. Illich’s radicalization of his critical discourse led to a confrontation with the Vatican in 1967 and 1968 after he published “The Seamy Side of Charity” and “The Vanishing Clergyman” in the last year, 1967, of the CIF Report. The conflict with the Vatican signaled Illich’s turn to educational, health and other issues moving away from a critique of the institutionalized Catholic Church.Este artículo examina los Reports del Center of Intercultural Formation (CIF que fueron elaborados en Cuernavaca, México, entre 1962 y 1967 por el Centro de Investigaciones Culturales (CIC, y producidos desde 1963 por el Centro Intercultural de Documentación constituido dentro del CIC. Esta red de centros es situada dentro de la coyuntura histórica del principio de los años sesenta y de la convergencia entre el Vaticano y la Alianza para el Progreso y sus proyectos comunitarios desarrollistas. El artículo se centra en la

  9. Teaching Teaching & Understanding Understanding

    DEFF Research Database (Denmark)

    2006-01-01

    "Teaching Teaching & Understanding Understanding" is a 19-minute award-winning short-film about teaching at university and higher-level educational institutions. It is based on the "Constructive Alignment" theory developed by Prof. John Biggs. The film delivers a foundation for understanding what...

  10. The effects of infographics and several quantitative versus qualitative formats for cardiovascular disease risk, including heart age, on people's risk understanding.

    NARCIS (Netherlands)

    Damman, Olga C; Vonk, Suzanne I; Van den Haak, Maaike J; van Hooijdonk, Charlotte M J; Timmermans, Danielle R M

    2018-01-01

    To study how comprehension of cardiovascular disease (CVD) risk is influenced by: (1) infographics about qualitative risk information, with/without risk numbers; (2) which qualitative risk dimension is emphasized; (3) heart age vs. traditional risk format.

  11. The effect of different cardiovascular risk presentation formats on intentions, understanding and emotional affect: a randomised controlled trial using a web-based risk formatter (protocol).

    NARCIS (Netherlands)

    Waldron, C.A.; Gallacher, J.; Weijden, G.D.E.M. van der; Newcombe, R.; Elwyn, G.

    2010-01-01

    BACKGROUND: The future risk of heart disease can be predicted with increasing precision. However, more research is needed into how this risk is conveyed and presented. The aim of this study is to compare the effects of presenting cardiovascular risk in different formats on individuals' intention to

  12. Understanding causes of tree growth response to gap formation: D13C-values in tree rings reveal a predominant effect of light

    NARCIS (Netherlands)

    Sleen, van der J.P.; Soliz-Gamboa, C.C.; Helle, G.; Pons, T.L.; Anten, N.P.R.; Zuidema, P.A.

    2014-01-01

    Carbon isotope ratios in growth rings of a tropical tree species show that treefall gaps stimulate diameter growth mainly through changes in the availability of light and not water. The formation of treefall gaps in closed canopy forests usually entails considerable increases in light and nutrient

  13. Understanding causes of tree growth response to gap formation: D13C-values in tree rings reveal a predominant effect of light

    NARCIS (Netherlands)

    van der Sleen, Peter; Soliz Gamboa, Claudia; Helle, G.; Pons, Thijs; Anten, Niels; Zuidema, Pieter

    2014-01-01

    Key message Carbon isotope ratios in growth rings of a tropical tree species show that treefall gaps stimulate diameter growth mainly through changes in the availability of light and not water. The formation of treefall gaps in closed canopy forests usually entails considerable increases in light

  14. An approach of understanding acid volcanics and tuffaceous volcaniclastics from field studies: A case from Tadpatri Formation, Proterozoic Cuddapah basin, Andhra Pradesh, India

    Science.gov (United States)

    Goswami, Sukanta; Upadhyay, P. K.; Bhagat, Sangeeta; Zakaulla, Syed; Bhatt, A. K.; Natarajan, V.; Dey, Sukanta

    2018-03-01

    The lower stratigraphic part of the Cuddapah basin is marked by mafic and felsic volcanism. Tadpatri Formation consists of a greater variety of rock types due to bimodal volcanism in the upper part. Presence of bimodal volcanism is an indication of continental rift setting. Various genetic processes involved in the formation of such volcanic sequence result in original textures which are classified into volcaniclastic and coherent categories. Detailed and systematic field works in Tadpatri-Tonduru transect of SW Cuddapah basin have provided information on the physical processes producing this diversity of rock types. Felsic volcanism is manifested here with features as finger print of past rhyolite-dacite eruptions. Acid volcanics, tuffs and associated shale of Tadpatri Formation are studied and mapped in the field. With supporting subordinate studies on geochemistry, mineralogy and petrogenesis of the volcanics to validate field features accurately, it is understood that volcanism was associated with rifting and shallow marine environmental condition. Four facies (i.e., surge, flow, fall and resedimented volcaniclastic) are demarcated to describe stratigraphic units and volcanic history of the mapped area. The present contribution focuses on the fundamental characterization and categorization of field-based features diagnostic of silica-rich volcanic activities in the Tadpatri Formation.

  15. Intermediate Scale Laboratory Testing to Understand Mechanisms of Capillary and Dissolution Trapping during Injection and Post-Injection of CO2 in Heterogeneous Geological Formations

    Energy Technology Data Exchange (ETDEWEB)

    Illangasekare, Tissa [Colorado School of Mines, Golden, CO (United States); Trevisan, Luca [Colorado School of Mines, Golden, CO (United States); Agartan, Elif [Colorado School of Mines, Golden, CO (United States); Mori, Hiroko [Colorado School of Mines, Golden, CO (United States); Vargas-Johnson, Javier [Colorado School of Mines, Golden, CO (United States); Gonzalez-Nicolas, Ana [Colorado School of Mines, Golden, CO (United States); Cihan, Abdullah [Colorado School of Mines, Golden, CO (United States); Birkholzer, Jens [Colorado School of Mines, Golden, CO (United States); Zhou, Quanlin [Colorado School of Mines, Golden, CO (United States)

    2015-03-31

    Carbon Capture and Storage (CCS) represents a technology aimed to reduce atmospheric loading of CO2 from power plants and heavy industries by injecting it into deep geological formations, such as saline aquifers. A number of trapping mechanisms contribute to effective and secure storage of the injected CO2 in supercritical fluid phase (scCO2) in the formation over the long term. The primary trapping mechanisms are structural, residual, dissolution and mineralization. Knowledge gaps exist on how the heterogeneity of the formation manifested at all scales from the pore to the site scales affects trapping and parameterization of contributing mechanisms in models. An experimental and modeling study was conducted to fill these knowledge gaps. Experimental investigation of fundamental processes and mechanisms in field settings is not possible as it is not feasible to fully characterize the geologic heterogeneity at all relevant scales and gathering data on migration, trapping and dissolution of scCO2. Laboratory experiments using scCO2 under ambient conditions are also not feasible as it is technically challenging and cost prohibitive to develop large, two- or three-dimensional test systems with controlled high pressures to keep the scCO2 as a liquid. Hence, an innovative approach that used surrogate fluids in place of scCO2 and formation brine in multi-scale, synthetic aquifers test systems ranging in scales from centimeter to meter scale developed used. New modeling algorithms were developed to capture the processes controlled by the formation heterogeneity, and they were tested using the data from the laboratory test systems. The results and findings are expected to contribute toward better conceptual models, future improvements to DOE numerical codes, more accurate assessment of storage capacities, and optimized placement strategies. This report presents the experimental and modeling methods

  16. Experimental formation of Pb, Sn, Ge and Sb sulfides, selenides and chlorides in the presence of sal ammoniac: A contribution to the understanding of the mineral formation processes in coal wastes self-ignition

    Czech Academy of Sciences Publication Activity Database

    Laufek, F.; Veselovský, F.; Drábek, M.; Kříbek, B.; Klementová, Mariana

    176-177, May (2017), s. 1-7 ISSN 0166-5162 Institutional support: RVO:68378271 Keywords : coal wastes * metalloids * mineral formation * self-burning processes Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 4.783, year: 2016

  17. Interaction of amines with native aluminium oxide layers in non-aqueous environment: Application to the understanding of the formation of epoxy-amine/metal interphases

    Energy Technology Data Exchange (ETDEWEB)

    Mercier, D.; Rouchaud, J.-C. [Centre d' Etudes de Chimie Metallurgique, CNRS, 15 rue Georges Urbain, 94407 Vitry Cedex (France); Barthes-Labrousse, M.-G. [Centre d' Etudes de Chimie Metallurgique, CNRS, 15 rue Georges Urbain, 94407 Vitry Cedex (France)], E-mail: marie-genevieve.barthes@u-psud.fr

    2008-08-15

    Interaction of propylamine (PA), 1,2-diaminoethane (DAE) or 3-aminomethyl-3,5,5-trimethylcyclohexylamine (isophorone diamine, IPDA) with native aluminium oxide layers in non-aqueous environment has been studied using time-resolved inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray photoelectron spectroscopy (XPS). The formation of several surface complexes has been evidenced. Monodentate and bidentate metal-bond surface complexes (MBSC) result from interactions between the amine terminations of the molecule and aluminium cations by donation of the N lone electron pair to the metal ion (Lewis-like mechanism leading to O-Al...N bonds). Monodentate and bidentate hydrogen-bond surface complexes (HBSC) are due to interaction of the amino group with surface hydroxyl groups by protonation of the amine termination (Bronsted-like mechanism leading to the formation of Al-OH...N bonds) or interaction with carbonaceous contamination (C{sub x}O{sub y}H{sub z}...N bonds). Diamines can also form mixed complexes with one amino group forming an O-Al...N bond and the other group forming an Al-OH...N or C{sub x}O{sub y}H{sub z}...N bond. Al-OH...N and C{sub x}O{sub y}H{sub z}...N bonds are less stable under vacuum than O-Al...N bonds, leading to partial desorption of the DAE molecules in vacuum and modification of the interaction modes. Only DAE and IPDA can lead to partial dissolution of the aluminium native (hydr)oxide films. A detailed mechanism of dissolution has been proposed based on the formation of mononuclear bidentate (chelate) MBSC by ligand exchange between the terminal {eta}{sup 1}-OH and bridged {mu}{sub 2}-OH surface sites and the amino terminations of the molecule. The detachment of this complex from the surface is likely to be the precursor step to the formation of the interphase in epoxy-amine/metal systems.

  18. ngVLA Key Science Goal 5: Understanding the Formation and Evolution of Stellar and Supermassive Black Holes in the Era of Multi-Messenger Astronomy

    Science.gov (United States)

    Lazio, T. Joseph W.; Maccarone, Thomas J.; Chomiuk, Laura; ngVLA Science Working Group 2, ngVLA Science Working Group 4

    2018-01-01

    The ngVLA will be a powerful telescope for finding and studying black holes, surveying everything from the remnants of massive stars to the supermassive black holes that lurk in the centers of galaxies. High-resolution imaging abilities will allow the separation of low-luminosity black holes in the local Universe from background sources, thereby providing critical constraints on the formation and growth of black holes of all sizes. Its combination of sensitivity and angular resolution will provide new constraints on the physics of black hole accretion and jet formation. Combined with facilities across the spectrum and gravitational wave observatories, the ngVLA will provide crucial constraints on the interaction of supermassive black holes with their environments, with implications for the evolution of galaxies and the emission of gravitational waves from in-spiraling supermassive black holes. The ngVLA will identify the radio counterparts to transient sources discovered by gravitational wave, neutrino, and optical observatories, and its high-resolution, fast-mapping capabilities will make it the preferred instrument to pinpoint electromagnetic counterparts to events such as supermassive black hole mergers.Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  19. Rates of star formation

    International Nuclear Information System (INIS)

    Larson, R.B.

    1977-01-01

    It is illustrated that a theoretical understanding of the formation and evolution of galaxies depends on an understanding of star formation, and especially of the factors influencing the rate of star formation. Some of the theoretical problems of star formation in galaxies, some approaches that have been considered in models of galaxy evolution, and some possible observational tests that may help to clarify which processes or models are most relevant are reviewed. The material is presented under the following headings: power-law models for star formation, star formation processes (conditions required, ways of achieving these conditions), observational indications and tests, and measures of star formation rates in galaxies. 49 references

  20. Understanding the formation and influence of attitudes in patients' treatment choices for lower back pain: Testing the benefits of a hybrid choice model approach

    DEFF Research Database (Denmark)

    Kløjgaard, Mirja Elisabeth; Hess, S.

    2014-01-01

    A growing number of studies across different fields are making use of a new class of choice models, labelled variably as hybrid model structures or integrated choice and latent variable models, and incorporating the role of attitudes in decision making. To date, this technique has not been used...... in health economics. The present paper looks at the formation of such attitudes and their role in patients treatment choices in the context of low back pain. We use stated choice data collected from a sample of 561 patients with 348 respondents referred to a regional spine centre in Middelfart, Denmark...... in spring/summer 2012. We show how the hybrid model structure is able to make a link between attitudinal questions and treatment choices, and also explains variation of these attitudes across key socio-demographic groups. However, we also show how, in this case, only a small share of the overall...

  1. Adaptive radiation of Pseudomonas fluorescens SBW25 in experimental microcosms provides an understanding of the evolutionary ecology and molecular biology of A-L interface biofilm formation.

    Science.gov (United States)

    Koza, Anna; Kusmierska, Anna; McLaughlin, Kimberley; Moshynets, Olena; Spiers, Andrew J

    2017-07-03

    Combined experimental evolutionary and molecular biology approaches have been used to investigate the adaptive radiation of Pseudomonas fluorescens SBW25 in static microcosms leading to the colonisation of the air-liquid interface by biofilm-forming mutants such as the Wrinkly Spreader (WS). In these microcosms, the ecosystem engineering of the early wild-type colonists establishes the niche space for subsequent WS evolution and colonisation. Random WS mutations occurring in the developing population that deregulate diguanylate cyclases and c-di-GMP homeostasis result in cellulose-based biofilms at the air-liquid interface. These structures allow Wrinkly Spreaders to intercept O2 diffusing into the liquid column and limit the growth of competitors lower down. As the biofilm matures, competition increasingly occurs between WS lineages, and niche divergence within the biofilm may support further diversification before system failure when the structure finally sinks. A combination of pleiotropic and epistasis effects, as well as secondary mutations, may explain variations in WS phenotype and fitness. Understanding how mutations subvert regulatory networks to express intrinsic genome potential and key innovations providing a selective advantage in novel environments is key to understanding the versatility of bacteria, and how selection and ecological opportunity can rapidly lead to substantive changes in phenotype and in community structure and function. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. Understanding the formation and evolution of early-type galaxies based on newly developed single-burst stellar population synthesis models in the infrared

    Science.gov (United States)

    Roeck, Benjamin

    2015-12-01

    whole optical and infrared wavelength range between 3500 and 50000Å which are almost completely based on spectra of observed stars (apart from two gaps which were fitted with theoretical stellar spectra) . We analyze the behaviour of the near-infrared (J - K) and the Spitzer ([3.6]-[4.5]) colour calculated from our models. For ages older than 3 Gyr, both colours depend only slightly on age and metallicity. However, for younger ages, both colours become redder which is caused by the asymptotic giant branch stars contributing significantly to the light in the infrared at ages between 0.1 and 3 Gyr. Furthermore, we find a satisfactory agreement between the optical and near-infrared colours measured from our models and the colours observed from various samples of globular clusters and early-type x galaxies. However, our model predictions are only able to reproduce correctly the Spitzer ([3.6]-[4.5]) colours of older, more massive galaxies that resemble a single-burst population. Younger, less massive and more metal-poor galaxies show redder colours than our models. This mismatch can be explained by a more extended star formation history of these galaxies which includes a metal-poor or/and young population. The Spitzer ([3.6]-[4.5]) colours derived from our models also agree very well with those from most other models available in this wavelength range as long as they also correctly take into account a strong CO absorption band situated at 4.5 μm. The model predictions for colours in the near-infrared, such as (J - K), differ more between the different sets of models, depending on the underlying prescriptions for the asymptotic giant branch stellar evolutionary phase. Compared to other authors, we adopt only a moderate contribution of asymptotic giant branch stars to our models. Our stellar population models allow us also to determine mass-to-light ratios in different infrared bands. Consequently, we can confirm that the massto- light ratio determined in the Spitzer [3

  3. Understanding the formation of ancient intertropical disjunct distributions using Asian and Neotropical hinged-teeth snakes (Sibynophis and Scaphiodontophis: Serpentes: Colubridae).

    Science.gov (United States)

    Chen, Xin; Huang, Song; Guo, Peng; Colli, Guarino R; Nieto Montes de Oca, Adrián; Vitt, Laurie J; Pyron, R Alexander; Burbrink, Frank T

    2013-01-01

    Numerous taxa show ancient intertropical disjunct distributions. Many can be explained by well-known processes of historical vicariance, such as the breakup of Gondwanaland. Others, such as Asian-Neotropical divergences are not as well understood. To clarify the phylogenetic position and understand biogeographic and temporal origins of the geographically disjunct and morphologically unique genera of hinged-teeth snakes, Scaphiodontophis (n=1) and Sibynophis (n=9; Colubridae), we inferred a time-calibrated phylogeny with additional 107 taxa representing the superfamily Colubroidea using four genes (c-mos, cyt-b, ND2, RAG-1; 3085 bp). We used this tree to estimate ancestral areas for the group. The results show that Scaphiodontophis is sister to Sibynophis, both originated in the late Eocene/Oligocene in Asia and likely dispersed through Beringia to the New World, but unlike other snake groups left no extant species in temperate North America. Current recognition of Scaphiodontophiinae renders Colubrinae paraphyletic, and we resurrect the previously named subfamily Sibynophiinae to encompass both genera and use the tribes Sibynophiini (Sibynophis) and Scaphiodontophiini (Scaphiodontophis) to highlight the geographically distinct areas occupied by these taxa. These results suggest that intercontinental dispersal with extinction in intermediate areas can explain puzzling patterns of ancient intertropical disjunct distributions. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Understanding the visual resource

    Science.gov (United States)

    Floyd L. Newby

    1971-01-01

    Understanding our visual resources involves a complex interweaving of motivation and cognitive recesses; but, more important, it requires that we understand and can identify those characteristics of a landscape that influence the image formation process. From research conducted in Florida, three major variables were identified that appear to have significant effect...

  5. Understanding Carbohydrates

    Science.gov (United States)

    ... Size: A A A Listen En Español Understanding Carbohydrates How much and what type of carbohydrate foods ... glucose levels in your target range. Explore: Understanding Carbohydrates Glycemic Index and Diabetes Learn about the glycemic ...

  6. Understanding classification

    NARCIS (Netherlands)

    Subianto, M.

    2009-01-01

    In practical data analysis, the understandability of models plays an important role in their acceptance. In the data mining literature, however, understandability plays is hardly ever mentioned. If it is mentioned, it is interpreted as meaning that the models have to be simple. In this thesis we

  7. Embodied understanding.

    Science.gov (United States)

    Johnson, Mark

    2015-01-01

    Western culture has inherited a view of understanding as an intellectual cognitive operation of grasping of concepts and their relations. However, cognitive science research has shown that this received intellectualist conception is substantially out of touch with how humans actually make and experience meaning. The view emerging from the mind sciences recognizes that understanding is profoundly embodied, insofar as our conceptualization and reasoning recruit sensory, motor, and affective patterns and processes to structure our understanding of, and engagement with, our world. A psychologically realistic account of understanding must begin with the patterns of ongoing interaction between an organism and its physical and cultural environments and must include both our emotional responses to changes in our body and environment, and also the actions by which we continuously transform our experience. Consequently, embodied understanding is not merely a conceptual/propositional activity of thought, but rather constitutes our most basic way of being in, and engaging with, our surroundings in a deep visceral manner.

  8. Understanding delusions

    Directory of Open Access Journals (Sweden)

    Chandra Kiran

    2009-01-01

    Full Text Available Delusion has always been a central topic for psychiatric research with regard to etiology, pathogenesis, diagnosis, treatment, and forensic relevance. The various theories and explanations for delusion formation are reviewed. The etiology, classification and management of delusions are briefly discussed. Recent advances in the field are reviewed.

  9. Understanding semantics

    DEFF Research Database (Denmark)

    Thrane, Torben

    1997-01-01

    Understanding natural language is a cognitive, information-driven process. Discussing some of the consequences of this fact, the paper offers a novel look at the semantic effect of lexical nouns and the identification of reference types....

  10. Understanding Alzheimer's

    Science.gov (United States)

    ... Navigation Bar Home Current Issue Past Issues Understanding Alzheimer's Past Issues / Fall 2007 Table of Contents For ... and brain scans. No treatment so far stops Alzheimer's. However, for some in the disease's early and ...

  11. Understanding homelessness

    OpenAIRE

    Somerville, Peter

    2013-01-01

    This paper reviews the literature on understanding homelessness. It criticizes approaches that ignore, distort or diminish the humanity of homeless people, or else, add little to our understanding of that humanity. In particular, it rejects what it calls “epidemiological” approaches, which deny the possibility of agency for homeless people, insofar as those approaches view the situation of those people largely as a “social fact”, to be explained in terms of causal variables or “risk factors” ...

  12. Understanding MARC: Another Look

    Directory of Open Access Journals (Sweden)

    Roy Chang

    1989-12-01

    Full Text Available 無MARC format has been widely used and discussed in our profession. However, there appear to have a wide spread misunderstanding of its real structure and attributes. This article discuss the needs for us to understand it a little more. Also, it presents the general misconceptions about MARC, the compatibility of MARC, the structure of MARC, standardization and - data communication, and some major issues related to MARC format. In this library automation age, MARC is a key element in library services, and it deserves us to take another look.

  13. Understanding Maple

    CERN Document Server

    Thompson, Ian

    2016-01-01

    Maple is a powerful symbolic computation system that is widely used in universities around the world. This short introduction gives readers an insight into the rules that control how the system works, and how to understand, fix, and avoid common problems. Topics covered include algebra, calculus, linear algebra, graphics, programming, and procedures. Each chapter contains numerous illustrative examples, using mathematics that does not extend beyond first-year undergraduate material. Maple worksheets containing these examples are available for download from the author's personal website. The book is suitable for new users, but where advanced topics are central to understanding Maple they are tackled head-on. Many concepts which are absent from introductory books and manuals are described in detail. With this book, students, teachers and researchers will gain a solid understanding of Maple and how to use it to solve complex mathematical problems in a simple and efficient way.

  14. Understanding physics

    CERN Document Server

    Mansfield, Michael

    2011-01-01

    Understanding Physics - Second edition is a comprehensive, yet compact, introductory physics textbook aimed at physics undergraduates and also at engineers and other scientists taking a general physics course. Written with today's students in mind, this text covers the core material required by an introductory course in a clear and refreshing way. A second colour is used throughout to enhance learning and understanding. Each topic is introduced from first principles so that the text is suitable for students without a prior background in physics. At the same time the book is designed to enable

  15. Understanding Energy

    Science.gov (United States)

    Menon, Deepika; Shelby, Blake; Mattingly, Christine

    2016-01-01

    "Energy" is a term often used in everyday language. Even young children associate energy with the food they eat, feeling tired after playing soccer, or when asked to turn the lights off to save light energy. However, they may not have the scientific conceptual understanding of energy at this age. Teaching energy and matter could be…

  16. Understanding translation

    DEFF Research Database (Denmark)

    Schjoldager, Anne Gram; Gottlieb, Henrik; Klitgård, Ida

    Understanding Translation is designed as a textbook for courses on the theory and practice of translation in general and of particular types of translation - such as interpreting, screen translation and literary translation. The aim of the book is to help you gain an in-depth understanding...... of the phenomenon of translation and to provide you with a conceptual framework for the analysis of various aspects of professional translation. Intended readers are students of translation and languages, but the book will also be relevant for others who are interested in the theory and practice of translation...... - translators, language teachers, translation users and literary, TV and film critics, for instance. Discussions focus on translation between Danish and English....

  17. Understanding Resilience

    Directory of Open Access Journals (Sweden)

    Gang eWu

    2013-02-01

    Full Text Available Resilience is the ability to adapt successfully in the face of stress and adversity. Stressful life events, trauma and chronic adversity can have a substantial impact on brain function and structure, and can result in the development of PTSD, depression and other psychiatric disorders. However, most individuals do not develop such illnesses after experiencing stressful life events, and are thus thought to be resilient. Resilience as successful adaptation relies on effective responses to environmental challenges and ultimate resistance to the deleterious effects of stress, therefore a greater understanding of the factors that promote such effects is of great relevance. This review focuses on recent findings regarding genetic, epigenetic, developmental, psychosocial and neurochemical factors that are considered essential contributors to the development of resilience. Neural circuits and pathways involved in mediating resilience are also discussed. The growing understanding of resilience factors will hopefully lead to the development of new pharmacological and psychological interventions for enhancing resilience and mitigating the untoward consequences.

  18. Understand electronics

    CERN Document Server

    Bishop, Owen

    2013-01-01

    Understand Electronics provides a readable introduction to the exciting world of electronics for the student or enthusiast with little previous knowledge. The subject is treated with the minimum of mathematics and the book is extensively illustrated.This is an essential guide for the newcomer to electronics, and replaces the author's best-selling Beginner's Guide to Electronics.The step-by-step approach makes this book ideal for introductory courses such as the Intermediate GNVQ.

  19. Understanding users

    DEFF Research Database (Denmark)

    Johannsen, Carl Gustav Viggo

    2014-01-01

    Segmentation of users can help libraries in the process of understanding user similarities and differences. Segmentation can also form the basis for selecting segments of target users and for developing tailored services for specific target segments. Several approaches and techniques have been...... segmentation project using computer-generated clusters. Compared to traditional marketing texts, this article also tries to identify user segments or images or metaphors by the library profession itself....

  20. Understanding unemployment

    OpenAIRE

    Guillaume Rocheteau

    2006-01-01

    Modern economists have built models of the labor market, which isolate the market’s key drivers and describe the way these interact to produce particular levels of unemployment. One of the most popular models used by macroeconomists today is the search-matching model of equilibrium unemployment. We explain this model, and show how it can be applied to understand the way various policies, such as unemployment benefits, taxes, or technological changes, can affect the unemployment rate.

  1. Understanding Technology?

    Directory of Open Access Journals (Sweden)

    Erik Bendtsen

    2016-11-01

    Full Text Available We are facing radical changes in our ways of living in the nearest future. Not necessarily of our own choice, but because tchnological development is moving so fast, that it will have still greater impact on many aspects of our lives. We have seen the beginnings of that change within the latest 35 years or so, but according to newest research that change will speed up immensely in the nearest years to come. The impact of that change or these changes will affect our working life immensely as a consequence of automation. How these changes are brought about and which are their consequences in a broad sense is being attempted to be understood and guessed by researchers. No one knows for sure, but specific patterns are visible. This paper will not try to guess, what will come, but will rather try to understand the deepest ”nature” of technology in order to understand the driving factors in this development: the genesis of technology in a broad sense in order to contibute to the understanding of the basis for the expected development.

  2. Understanding uncertainty

    CERN Document Server

    Lindley, Dennis V

    2013-01-01

    Praise for the First Edition ""...a reference for everyone who is interested in knowing and handling uncertainty.""-Journal of Applied Statistics The critically acclaimed First Edition of Understanding Uncertainty provided a study of uncertainty addressed to scholars in all fields, showing that uncertainty could be measured by probability, and that probability obeyed three basic rules that enabled uncertainty to be handled sensibly in everyday life. These ideas were extended to embrace the scientific method and to show how decisions, containing an uncertain element, could be rationally made.

  3. Stellar formation

    CERN Document Server

    Reddish, V C

    1978-01-01

    Stellar Formation brings together knowledge about the formation of stars. In seeking to determine the conditions necessary for star formation, this book examines questions such as how, where, and why stars form, and at what rate and with what properties. This text also considers whether the formation of a star is an accident or an integral part of the physical properties of matter. This book consists of 13 chapters divided into two sections and begins with an overview of theories that explain star formation as well as the state of knowledge of star formation in comparison to stellar structure

  4. Understanding analysis

    CERN Document Server

    Abbott, Stephen

    2015-01-01

    This lively introductory text exposes the student to the rewards of a rigorous study of functions of a real variable. In each chapter, informal discussions of questions that give analysis its inherent fascination are followed by precise, but not overly formal, developments of the techniques needed to make sense of them. By focusing on the unifying themes of approximation and the resolution of paradoxes that arise in the transition from the finite to the infinite, the text turns what could be a daunting cascade of definitions and theorems into a coherent and engaging progression of ideas. Acutely aware of the need for rigor, the student is much better prepared to understand what constitutes a proper mathematical proof and how to write one. Fifteen years of classroom experience with the first edition of Understanding Analysis have solidified and refined the central narrative of the second edition. Roughly 150 new exercises join a selection of the best exercises from the first edition, and three more project-sty...

  5. Understanding ayurveda.

    Science.gov (United States)

    Gadgil, Vaidya Dilip

    2010-01-01

    Ayurveda needs to achieve its full potential both in India and globally. This requires imparting to its students full appreciation of Ayurveda's power and strength, particularly proper understanding of the advantages of applying it to treat chronic and acute diseases. To this end, we explain the necessity of learning Sanskrit as a medium of study, and the advantages of learning the Texts in the traditional way, rather than relying on translations with all the loss of meaning and precision, which that entails. We emphasize the use of Triskandhakosha as a means to fully understand Ayurveda fundamental concepts and technical terms, so that all their shades of meaning are fully understood, and all their usages given in different places in the texts. Only by such methods can full appreciation of Ayurvedic wisdom be achieved, and the full depth and power of its knowledge be applied. Only then will its true status among systems of medicine come to be appreciated, either in India or more widely in the world as a whole.

  6. Understanding Ayurveda

    Directory of Open Access Journals (Sweden)

    Vaidya Dilip Gadgil

    2010-01-01

    Full Text Available Ayurveda needs to achieve its full potential both in India and globally. This requires imparting to its students full appreciation of Ayurveda′s power and strength, particularly proper understanding of the advantages of applying it to treat chronic and acute diseases. To this end, we explain the necessity of learning Sanskrit as a medium of study, and the advantages of learning the Texts in the traditional way, rather than relying on translations with all the loss of meaning and precision, which that entails. We emphasize the use of Triskandhakosha as a means to fully understand Ayurveda fundamental concepts and technical terms, so that all their shades of meaning are fully understood, and all their usages given in different places in the texts. Only by such methods can full appreciation of Ayurvedic wisdom be achieved, and the full depth and power of its knowledge be applied. Only then will its true status among systems of medicine come to be appreciated, either in India or more widely in the world as a whole.

  7. Understanding physics

    CERN Document Server

    Cassidy, David; Rutherford, James

    2002-01-01

    Understanding Physics provides a thorough grounding in contemporary physics while placing physics into its social and historical context Based in large part on the highly respected Project Physics Course developed by two of the authors, it also integrates the results of recent pedagogical research The text thus - teaches about the basic phenomena in the physical world and the concepts developed to explain them - shows that science is a rational human endeavor with a long and continuing tradition, involving many different cultures and people - develops facility in critical thinking, reasoned argumentation, evaluation of evidence, mathematical modeling, and ethical values The treatment emphasizes not only what we know but also how we know it, why we believe it, and what effects that knowledge has - Why do we believe the Earth and planets revolve around the Sun? - Why do we believe that matter is made of atoms? - How do relativity theory and quantum mechanics alter our conception of Nature and in what ways do th...

  8. Soil formation.

    NARCIS (Netherlands)

    Breemen, van N.; Buurman, P.

    1998-01-01

    Soil Formation deals with qualitative and quantitative aspects of soil formation (or pedogenesis) and the underlying chemical, biological, and physical processes. The starting point of the text is the process - and not soil classification. Effects of weathering and new formation of minerals,

  9. Understanding PISA

    Directory of Open Access Journals (Sweden)

    Stephen DOWNES

    2005-04-01

    Full Text Available Understanding PISA Stephen DOWNESMoncton, CANADA ABSTRACT The headline was dramatic enough to cause a ripple in the reading public. "Students who use computers a lot at school have worse maths and reading performance," noted the BBC news article, citing a 2004 study by Ludger Woessmann and Thomas Fuchs (Fuchs and Woessman, 2004. It was not long before the blogosphere took notice. Taking the theme and running with it, Alice and Bill ask, "Computers Make School Kids Dumber?" They theorize, "If you track the admitted decline of education, you'll probably notice that it follows along with the increase of technology in the classroom." In a similar vein, James Bartholomew asks, "Do you think that the government will turn down the volume of its boasting about how it has spent billions introducing computers in schools (while keeping down the pay of teachers so much that there are shortages? Do you think it will stop sending governors of state schools glossy pamphlets about insisting that computers are used in their schools as much as possible?" In this study, therefore, PISA looks well beyond educational attainment, and also includes school demographics, such as whether it is a public or private school, has large or small classes, or has access or not to technological resources. Finally, it does measure student information-their family background, access to books and computers and parental support as well. The PISA survey departs from previous surveys in disregarding the stated curricula of the schools being measured. Therefore, the conclusion is not surprising, nor even wrong for him to consider independently of any parental or teacher support, considered without reference to the software running on it, considered without reference to student attitudes and interests, does not positively impact an education. Finally, he focus on missing the reporting of results

  10. environmental impacts of crud local government area ol impacts of ...

    African Journals Online (AJOL)

    pc

    2017-06-01

    Jun 1, 2017 ... rigs and wells, as well as roducts (such as gasoline, ts, and heavier fuels used er fuel, or the spill of any or waste oil. Spills may o clean up. Oil also enters m natural oil seeps. Public as tended to focus most ers. Oil spillage is one of problems. Oil communities end of this environmental ave generated a lot of.

  11. environmental impacts of crud local government area ol impacts of ...

    African Journals Online (AJOL)

    pc

    2017-06-01

    Jun 1, 2017 ... toxic heavy metal concentrations (iron, coppe above admissible ... pollution. The term often refers to marine oil sp where oil is released into the ocean or coastal wate. Oil spills include releases of crude oil from tanke offshore platforms ... concentrations of toxic heavy metal pollutants. Analyses were also ...

  12. Star formation

    International Nuclear Information System (INIS)

    Woodward, P.R.

    1978-01-01

    Theoretical models of star formation are discussed beginning with the earliest stages and ending in the formation of rotating, self-gravitating disks or rings. First a model of the implosion of very diffuse gas clouds is presented which relies upon a shock at the edge of a galactic spiral arm to drive the implosion. Second, models are presented for the formation of a second generation of massive stars in such a cloud once a first generation has formed. These models rely on the ionizing radiation from massive stars or on the supernova shocks produced when these stars explode. Finally, calculations of the gravitational collapse of rotating clouds are discussed with special focus on the question of whether rotating disks or rings are the result of such a collapse. 65 references

  13. Galaxy Formation

    DEFF Research Database (Denmark)

    Sparre, Martin

    Galaxy formation is an enormously complex discipline due to the many physical processes that play a role in shaping galaxies. The objective of this thesis is to study galaxy formation with two different approaches: First, numerical simulations are used to study the structure of dark matter and how...... galaxies form stars throughout the history of the Universe, and secondly it is shown that observations of gamma-ray bursts (GRBs) can be used to probe galaxies with active star formation in the early Universe. A conclusion from the hydrodynamical simulations is that the galaxies from the stateof...... is important, since it helps constraining chemical evolution models at high redshift. A new project studying how the population of galaxies hosting GRBs relate to other galaxy population is outlined in the conclusion of this thesis. The core of this project will be to quantify how the stellar mass function...

  14. Star formation

    Energy Technology Data Exchange (ETDEWEB)

    Woodward, P.R.

    1978-09-27

    Theoretical models of star formation are discussed beginning with the earliest stages and ending in the formation of rotating, self-gravitating disks or rings. First a model of the implosion of very diffuse gas clouds is presented which relies upon a shock at the edge of a galactic spiral arm to drive the implosion. Second, models are presented for the formation of a second generation of massive stars in such a cloud once a first generation has formed. These models rely on the ionizing radiation from massive stars or on the supernova shocks produced when these stars explode. Finally, calculations of the gravitational collapse of rotating clouds are discussed with special focus on the question of whether rotating disks or rings are the result of such a collapse. 65 references.

  15. The Systematic Medical Appraisal, Referral and Treatment (SMART Mental Health Project: Development and Testing of Electronic Decision Support System and Formative Research to Understand Perceptions about Mental Health in Rural India.

    Directory of Open Access Journals (Sweden)

    Pallab K Maulik

    Full Text Available Common mental disorders (CMD such as depression, suicidal risk and emotional/medically unexplained complaints affect a large number of people in India, but few receive appropriate care. Key reasons for this include few trained mental health professionals and stigma associated with mental health. A potential approach to address poor access to care is by training village healthcare workers in providing basic mental health care, and harnessing India's vast mobile network to support such workers using mobile-based applications. We propose an intervention to implement such an approach that incorporates the use of mobile-based electronic decision support systems (EDSS to provide mental health services for CMD, combined with a community-based anti-stigma campaign. This will be implemented and evaluated across 42 villages in Andhra Pradesh, a south Indian state. This paper discusses the development and testing of the EDSS, and the formative research that informed the anti-stigma campaign.The development of the EDSS used an iterative process that was validated against clinical diagnosis. A mixed methods approach tested the user acceptability of the EDSS. Focus group discussions and in-depth interviews provided community-level perceptions about mental health. This study involved 3 villages and one primary health centre.The EDSS application was found to be acceptable, but some modifications were needed. The community lacked adequate knowledge about CMD and its treatment and there was stigma associated with mental illness. Faith and traditional healers were considered to be important mental health service providers.A number of barriers and facilitators were identified in implementing the intervention analysed in a framework using Andersen's behavioural model of health services use.The findings assisted with refining the intervention prior to large-scale implementation and evaluation.

  16. Galaxy formation and evolution

    CERN Document Server

    Mo, Houjun; White, Simon

    2010-01-01

    The rapidly expanding field of galaxy formation lies at the interface between astronomy, particle physics, and cosmology. Covering diverse topics from these disciplines, all of which are needed to understand how galaxies form and evolve, this book is ideal for researchers entering the field. Individual chapters explore the evolution of the Universe as a whole and its particle and radiation content; linear and nonlinear growth of cosmic structure; processes affecting the gaseous and dark matter components of galaxies and their stellar populations; the formation of spiral and elliptical galaxies; central supermassive black holes and the activity associated with them; galaxy interactions; and the intergalactic medium. Emphasizing both observational and theoretical aspects, this book provides a coherent introduction for astronomers, cosmologists, and astroparticle physicists to the broad range of science underlying the formation and evolution of galaxies.

  17. Forces in strategy formation

    DEFF Research Database (Denmark)

    Steensen, Elmer Fly; Sanchez, Ron

    2008-01-01

    This chapter proposes that organizational strategy formation should be characterized theoretically as a process that is subject to several interacting forces, rather than represented by separate discrete decisionmodels or theoretic perspectives, as is commonly done in the strategic management...... literature. Based on an extensive review of relevant theory and empirical work in strategic decision-making, organizational change theory, cognitive and social psychology, and strategy processes, seven kinds of ''forces'' - rational, imposed, teleological, learning, political, heuristic, and social...... - are identified as interacting in and having significant influence on the strategy formation process. It is further argued that by applying a holistic ''forces-view'' of the significant and interacting influences on strategy formation, we can better understand the dynamics and challenges in managing the process...

  18. Principles of star formation

    CERN Document Server

    Bodenheimer, Peter H

    2011-01-01

    Understanding star formation is one of the key fields in present-day astrophysics. This book treats a wide variety of the physical processes involved, as well as the main observational discoveries, with key points being discussed in detail. The current star formation in our galaxy is emphasized, because the most detailed observations are available for this case. The book presents a comparison of the various scenarios for star formation, discusses the basic physics underlying each one, and follows in detail the history of a star from its initial state in the interstellar gas to its becoming a condensed object in equilibrium. Both theoretical and observational evidence to support the validity of the general evolutionary path are presented, and methods for comparing the two are emphasized. The author is a recognized expert in calculations of the evolution of protostars, the structure and evolution of disks, and stellar evolution in general. This book will be of value to graduate students in astronomy and astroph...

  19. THE ALLIANCE FORMATION PROCESS

    OpenAIRE

    Whipple, Judith M.; Frankel, Robert

    1998-01-01

    While interest in developing strategic alliances within the food system continues to increase, there remains considerable risk when firms adopt such a cooperative strategy. The risk is due in part to the lack of concrete guidelines that illustrate the steps or stages of alliance development and the important strategic and operational decisions required at each stage. The existence of such guidelines would facilitate alliance formation and enable managers and researchers to better understand a...

  20. Understanding Callisto's Atmosphere

    Science.gov (United States)

    Spencer, John

    2016-10-01

    We plan to address first-order questions about the nature and origin of the mysterious atmosphere of Callisto, including its composition, longitudinal distribution, formation, and support mechanisms. This investigation is made possible by the remarkable sensitivity of the COS instrument, which has recently detected faint 1304 A and 1356 A O I emission from Callisto's leading / Jupiter-facing quadrant. The emission is probably due to dissociation of O2 molecules in Callisto's atmosphere by photo-electrons, and resonant scattering from an extended atomic O corona. We suspect, from Galileo ionospheric data, that the atmosphere may be much denser, and brighter in emission, on the trailing hemisphere, as expected for a sputter-generated atmosphere, and propose to test the sputter generation hypothesis with 4-orbit COS integrations on the leading and trailing hemispheres. If the trailing side emissions are indeed brighter, the improved SNR there will also allow much improved determination of atmospheric and coronal composition and optical depth. The observations will set the stage for, and aid in planning of, the extensive observations of Callisto's environment planned for the JUICE mission. Because Callisto's atmospheric oxygen emissions are indirectly illuminated by sunlight, which is uniform and quantifiable, it is much easier to understand atmospheric spatial distribution, and thus origin, than on Europa and Ganymede were emissions depend on magnetospheric excitation which is spatially variable and poorly understood. Callisto's atmosphere thus provides a unique chance to better understand the oxygen atmospheres of all the icy Galilean moons.

  1. Terrestrial planet formation.

    Science.gov (United States)

    Righter, K; O'Brien, D P

    2011-11-29

    Advances in our understanding of terrestrial planet formation have come from a multidisciplinary approach. Studies of the ages and compositions of primitive meteorites with compositions similar to the Sun have helped to constrain the nature of the building blocks of planets. This information helps to guide numerical models for the three stages of planet formation from dust to planetesimals (~10(6) y), followed by planetesimals to embryos (lunar to Mars-sized objects; few 10(6) y), and finally embryos to planets (10(7)-10(8) y). Defining the role of turbulence in the early nebula is a key to understanding the growth of solids larger than meter size. The initiation of runaway growth of embryos from planetesimals ultimately leads to the growth of large terrestrial planets via large impacts. Dynamical models can produce inner Solar System configurations that closely resemble our Solar System, especially when the orbital effects of large planets (Jupiter and Saturn) and damping mechanisms, such as gas drag, are included. Experimental studies of terrestrial planet interiors provide additional constraints on the conditions of differentiation and, therefore, origin. A more complete understanding of terrestrial planet formation might be possible via a combination of chemical and physical modeling, as well as obtaining samples and new geophysical data from other planets (Venus, Mars, or Mercury) and asteroids.

  2. Understanding the History of the Great Patriotic War as the Most Important Element of Historical Consciousness Formation and Education Improvement (Book Review: The Great Bend of the Don. The Place of Decisive Battles of the Grea

    Directory of Open Access Journals (Sweden)

    Nikolay F. Bugay

    2018-02-01

    Full Text Available For the first time in the historiography, the problem of armed confrontation between the Red Army and the Wehrmacht is covered systematically and taking into account multiple factors, from the point of view of influence of geographic, political, demographic, social and economic conditions on the course of hostilities. The authors revive the memory of almost forgotten in the national historiography major tank battles of July 1942 on the southern wing of the Soviet-German front and prove that the number of armored vehicles and personnel strength is comparable with the most famous tank battle of Prokhorovka 1943. Assessing Order 227, the authors note that with this Order Stalin rejected the ideology of the “scythian war”, expressed in ideas about the vastness of the territory, unlimitedness of grains, the possibility of luring the enemy deep into the vast country. The book describes in detail the part in the armed struggle Romanian, Italian, Hungarian and other troops on the Soviet-German front. In Eastern Europe their actions in modern historiography are considered to be heroic. The problem of lend-lease on the southern flank of the Soviet-German front via the “Persian corridor” is analyzed by the authors. The book analyzes such components of the General problems of military daily life as a front-line everyday life, organization of health services. Without a comprehensive analysis of all the circumstances, it is impossible to understand the general course of military operations, to explain the reasons of the defeats and victories of the Red Army.

  3. Shape understanding system machine understanding and human understanding

    CERN Document Server

    Les, Zbigniew

    2015-01-01

    This is the third book presenting selected results of research on the further development of the shape understanding system (SUS) carried out by authors in the newly founded Queen Jadwiga Research Institute of Understanding. In this book the new term Machine Understanding is introduced referring to a new area of research aiming to investigate the possibility of building machines with the ability to understand. It is presented that SUS needs to some extent mimic human understanding and for this reason machines are evaluated according to the rules applied for the evaluation of human understanding. The book shows how to formulate problems and how it can be tested if the machine is able to solve these problems.    

  4. Understanding map projections: Chapter 15

    Science.gov (United States)

    Usery, E. Lynn; Kent, Alexander J.; Vujakovic, Peter

    2018-01-01

    It has probably never been more important in the history of cartography than now that people understand how maps work. With increasing globalization, for example, world maps provide a key format for the transmission of information, but are often poorly used. Examples of poor understanding and use of projections and the resultant maps are many; for instance, the use of rectangular world maps in the United Kingdom press to show Chinese and Korean missile ranges as circles, something which can only be achieved on equidistant projections and then only from one launch point (Vujakovic, 2014).

  5. Supermassive Black Holes and Galaxy Formation

    OpenAIRE

    Silk, Joseph

    2001-01-01

    The formation of supermassive black holes (SMBH) is intimately related to galaxy formation, although precisely how remains a mystery. I speculate that formation of, and feedback from, SMBH may alleviate problems that have arisen in our understanding of the cores of dark halos of galaxies.

  6. Cement Formation

    DEFF Research Database (Denmark)

    Telschow, Samira; Jappe Frandsen, Flemming; Theisen, Kirsten

    2012-01-01

    Cement production has been subject to several technological changes, each of which requires detailed knowledge about the high multiplicity of processes, especially the high temperature process involved in the rotary kiln. This article gives an introduction to the topic of cement, including...... an overview of cement production, selected cement properties, and clinker phase relations. An extended summary of laboratory-scale investigations on clinkerization reactions, the most important reactions in cement production, is provided. Clinker formations by solid state reactions, solid−liquid and liquid...

  7. Digtets formater

    DEFF Research Database (Denmark)

    Schmidt, Michael Kallesøe; Rasmussen, Krista Stinne Greve; Skriver, Svend

    2017-01-01

    definition of text and work can be supplemented by a hermeneutical dimension, thus taking various versions of works and the influence of their respective media (blog, book etc.) on the percipient into account. In connection with the theoretical considerations, a handful of recent works by Lea Marie...... Løppenthin, Olga Ravn, Mikkel Thykier, Caspar Eric, and Simon Grotrian are discussed. By using the format as a point of departure rather than applying a more conventional practice of close reading, the authors argue for a broad-spectred approach to literary analysis which focuses on aspects of the conception...

  8. Complexity and formative experiences

    Directory of Open Access Journals (Sweden)

    Roque Strieder

    2017-12-01

    Full Text Available The contemporaneity is characterized by instability and diversity calling into question certainties and truths proposed in modernity. We recognize that the reality of things and phenomena become effective as a set of events, interactions, retroactions and chances. This different frame extends the need for revision of the epistemological foundations that sustain educational practices and give them sense. The complex thinking is an alternative option for acting as a counterpoint to classical science and its reductionist logic and knowledge compartmentalization, as well as to answer to contemporary epistemological and educational challenges. It aims to associate different areas and forms of knowledge, without, however merge them, distinguishing without separating the several disciplines and instances of the realities. This study, in theoretical references, highlights the relevance of complex approaches to support formative experiences because also able to produce complexities in reflections about educational issues. We conclude that formative possibilities from complexity potentialize the resignification of human’s conception and the understanding of its singularity in interdependence; The understanding that pedagogical and educational activities is a constant interrogation about the possibilities of knowing the knowledge and reframe learning, far beyond knowing its functions and utilitarian purposes; and, as a formative possibility, places us on the trail of responsibility, not as something eventual, but present and indicative of freedom to choose to stay or go beyond.

  9. Planetesimals and Planet Formation

    Science.gov (United States)

    Chambers, John

    The first step in the standard model for planet formation is the growth of gravitationally bound bodies called ``planetesimals'' from dust grains in a protoplanetary disk. Currently, we do not know how planetesimals form, how long they take to form, or what their sizes and mechanical properties are. The goal of this proposal is to assess how these uncertainties affect subsequent stages of planetary growth and the kind of planetary systems that form. The work will address three particular questions: (i) Can the properties of small body populations in the modern Solar System constrain the properties of planetesimals? (ii) How do the properties of planetesimals affect the formation of giant planets? (iii) How does the presence of a water ice condensation front (the ``snow line'') in a disk affect planetesimal formation and the later stages of planetary growth? These questions will be examined with computer simulations of planet formation using new computer codes to be developed as part of the proposal. The first question will be addressed using a statistical model for planetesimal coagulation and fragmentation. This code will be merged with the proposer's Mercury N-body integrator code to model the dynamics of large protoplanets in order to address the second question. Finally, a self- consistent model of disk evolution and the radial transport of water ice and vapour will be added to examine the third question. A theoretical understanding of how planets form is one of the key goals of NASA and the Origins of Solar Systems programme. Researchers have carried out many studies designed to address this goal, but the questions of how planetesimals form and how their properties affect planet formation have received relatively little attention. The proposed work will help address these unsolved questions, and place other research in context by assessing the importance of planetesimal origins and properties for planet formation.

  10. Planetesimal formation starts at the snow line

    OpenAIRE

    Drążkowska, J; Alibert, Y

    2017-01-01

    Context. The formation stage of planetesimals represents a major gap in our understanding of the planet formation process. Late-stage planet accretion models typically make arbitrary assumptions about planetesimal and pebble distribution, while dust evolution models predict that planetesimal formation is only possible at some orbital distances. Aims. We wish to test the importance of the water snow line in triggering the formation of the first planetesimals during the gas-rich phase of a p...

  11. Planetesimal formation starts at the snow line

    OpenAIRE

    Drazkowska, Joanna; Alibert, Yann

    2017-01-01

    Planetesimal formation stage represents a major gap in our understanding of the planet formation process. The late-stage planet accretion models typically make arbitrary assumptions about planetesimals and pebbles distribution while the dust evolution models predict that planetesimal formation is only possible at some orbital distances. We want to test the importance of water snow line for triggering formation of the first planetesimals during the gas-rich phase of protoplanetary disk, when c...

  12. Understanding the Formation of the Rural in the Amazon Region

    Directory of Open Access Journals (Sweden)

    Cláudia de Souza

    2013-12-01

    Full Text Available COSTA, FRANCISCO DE ASSIS. Formação rural extrativista na Amazônia: os desafios do desenvolvimento capitalista - 1720-1970. Belém: NAEA, 2012. 154 páginas. (Coleção Economia Política da Amazônia. Série III – Formação Histórica; v.1. ISBN: 978-85-7143-102-7. Inclui bibliografias, fotos e gráficos.

  13. Understanding the Formation, Functions, and Challenges of Grassroots Leadership Teams

    Science.gov (United States)

    Lester, Jaime; Kezar, Adrianna J.

    2012-01-01

    This study examined the nature, characteristics, and challenges of grassroots leadership teams and the role of these factors in promoting cognitive complexity in order to provide insight into collective forms of bottom-up change. The study is framed by the literature on leadership teams. Using interviews from a case study conducted at five higher…

  14. Understanding Combustion and Soot Formation in Diesel Engines

    Science.gov (United States)

    2016-09-09

    as other biofuel options such as furanic fuels, it is clear that it will be critical to the Navy to have the ability to match new-generation...strategies to 2050, International Energy Agency, OECD Publications, 2006. 2. World Energy Outlook 2009. International Energy Agency. OECD

  15. Galaxy Formation

    CERN Document Server

    Longair, Malcolm S

    2008-01-01

    This second edition of Galaxy Formation is an up-to-date text on astrophysical cosmology, expounding the structure of the classical cosmological models from a contemporary viewpoint. This forms the background to a detailed study of the origin of structure and galaxies in the Universe. The derivations of many of the most important results are derived by simple physical arguments which illuminate the results of more advanced treatments. A very wide range of observational data is brought to bear upon these problems, including the most recent results from WMAP, the Hubble Space Telescope, galaxy surveys like the Sloan Digital Sky Survey and the 2dF Galaxy Redshift Survey, studies of Type 1a supernovae, and many other observations.

  16. COMPETENCYTHE FORMATION FOR LIFE

    Directory of Open Access Journals (Sweden)

    Milagros Mederos-Piñeiro

    2016-07-01

    Full Text Available The formation of life competences is the result of a quality education that prepares students to meet the challenges of a fast moving world where equality and equal opportunities should constitute premises of education; training them is a challenge teachers to assume new generations contribute actively to a better world. In Cuba are important research on the formation of communication competences and self-regulated learning in primary school. The paper shows the result of an investigation that provides a methodology for the formation of life competences in primary school education, used as an essential pathway research activity. The methodological approach of research has a quantitative approach and an explanatory scope to establish and make sense of understanding the causal relationship between the direction of research activity and training of life competences. Theoretical, empirical and mathematical-statistical, for characterizing the initial state, processing of results and analysis: research methods are used. The application of the methodology for the formation of life competences makes teachers lead the teaching-learning process with a research and transforming teaching concept, where the school is the protagonist of their learning and causes changes in their performances, which are evident in the formed competences related to effective and affective communication; the solution of problems related to life; the use of means in obtaining the knowledge and the expression of a behavior consistent with school and social demands. The effectiveness of the methodology confirms that there is a causal relationship between the direction of research activity by teachers and the formation of life competences in school.

  17. The Planet Formation Imager

    Science.gov (United States)

    Kraus, S.; Buscher, D. F.; Monnier, J. D.; PFI Science, the; Technical Working Group

    2014-04-01

    Among the most fascinating and hotly-debated areas in contemporary astrophysics are the means by which planetary systems are assembled from the large rotating disks of gas and dust which attend a stellar birth. Although important work is being done both in theory and observation, a full understanding of the physics of planet formation can only be achieved by opening observational windows able to directly witness the process in action. The key requirement is then to probe planet-forming systems at the natural spatial scales over which material is being assembled. By definition, this is the so-called Hill Sphere which delineates the region of influence of a gravitating body within its surrounding environment. The Planet Formation Imager project has crystallized around this challenging goal: to deliver resolved images of Hill-Sphere-sized structures within candidate planet-hosting disks in the nearest star-forming regions. In this contribution we outline the primary science case of PFI and discuss how PFI could significantly advance our understanding of the architecture and potential habitability of planetary systems. We present radiation-hydrodynamics simulations from which we derive preliminary specifications that guide the design of the facility. Finally, we give an overview about the interferometric and non-interferometric technologies that we are investigating in order to meet the specifications.

  18. Metaphor, skepticism, understanding Metaphor, skepticism, understanding

    Directory of Open Access Journals (Sweden)

    Helena Martins

    2010-05-01

    Full Text Available

    This paper examines the idea that metaphor is a basic cognitive tool from a Wittgensteinian point of view. One specific aspect of Wittgenstein’s legacy is explored, namely his account of verbal understanding. Two interconnected and notoriously difficult features of this account are highlighted and discussed: the idea that linguistic understanding is not an event or a process, but an “abiding condition” (Philosophical Investigations, §143-84; and the idea that neither the meaning of a linguistic expression nor our understanding of it can ever go beyond our capacity of explaining it (Philosophical Investigations, §75. This perspective is shown to be particularly apt in reflecting upon the virtues of metaphor as a means of understanding, especially because it allows for the avoidance of both essentialist and skeptical accounts.

    This paper examines the idea that metaphor is a basic cognitive tool from a Wittgensteinian point of view. One specific aspect of Wittgenstein’s legacy is explored, namely his account of verbal understanding. Two interconnected and notoriously difficult features of this account are highlighted and discussed: the idea that linguistic understanding is not an event or a process, but an “abiding condition” (Philosophical Investigations, §143-84; and the idea that neither the meaning of a linguistic expression nor our understanding of it can ever go beyond our capacity of explaining it (Philosophical Investigations, §75. This perspective is shown to be particularly apt in reflecting upon the virtues of metaphor as a means of understanding, especially because it allows for the avoidance of both essentialist and skeptical accounts

  19. Understanding Identity and Organizations

    DEFF Research Database (Denmark)

    Christensen, Lars Thøger

    2013-01-01

    The article reviews the book "Understanding Identity and Organizations," by Kate Kenny, Andrea Whitle, and Hugh Wilmott.......The article reviews the book "Understanding Identity and Organizations," by Kate Kenny, Andrea Whitle, and Hugh Wilmott....

  20. Understanding Hereditary Angioedema

    Science.gov (United States)

    ... Allergy Library ▸ Understanding Hereditary Angioedema Share | Understanding Hereditary Angioedema This article has been reviewed by Thanai Pongdee, MD, FAAAAI Hereditary Angioedema (HAE) is a rare genetic condition. People with ...

  1. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... Prognosis Questions to Ask about Your Diagnosis Research Understanding Cancer Prognosis Oncologist Anthony L. Back, M.D., ... find our information on Coping With Cancer helpful. Understanding Statistics About Survival Doctors estimate prognosis by using ...

  2. Understanding in mathematics

    CERN Document Server

    Sierpinska, Anna

    1994-01-01

    The concept of understanding in mathematics with regard to mathematics education is considered in this volume, the main problem for mathematics teachers being how to facilitate their students'' understanding of the mathematics being taught.

  3. Understanding Food Labels

    Science.gov (United States)

    ... Healthy eating for girls Understanding food labels Understanding food labels There is lots of info on food ... need to avoid because of food allergies. Other food label terms top In addition to the Nutrition ...

  4. MP3 the meaning of a format

    CERN Document Server

    Sterne, Jonathan

    2012-01-01

    Jonathan Sterne shows that understanding the historical meaning of the MP3, the world's most common format for recorded audio, involves rethinking the place of digital technologies in the broader universe of twentieth-century communication history.

  5. Valuation of Understanding

    DEFF Research Database (Denmark)

    Wiberg, Merete

    An important aim for the teacher in Higher Education is that students, in order to learn, achieve understanding in terms of being able to handle knowledge in a certain way. In this paper focus will be on understanding as a phenomenon which is permeated with values of what good understanding might...... be. Understanding is to be discussed as a phenomenon which in its definition is relative to the paradigm of educational thinking in which it is embedded. Paradigms of valuation of understanding in higher education will be viewed from two perspectives: An anglosaxon curriculum studies tradition...

  6. Memorandum of Understanding.

    Energy Technology Data Exchange (ETDEWEB)

    Siple, Bud H. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2014-07-01

    A Memorandum of Understanding establishes a clear understanding of how an agreement is going to be implemented. The Memorandum of Understanding allows all involved to specifically understand that they are agreeing to the same thing and the terms are clearly identified. It also includes the clear distinction of functions and the level of involvement of the agencies involved. Specifically, a Memorandum of Understanding gives a chance to all of those involved in the agreement to see on paper as to what they all have agreed to.

  7. Investigation of likely causes of white patch formation on irradiated WWER fuel rod claddings

    International Nuclear Information System (INIS)

    Bibilashvili, Yu.K.; Velioukhanov, V.P.; Ioltoukhovski, A.Y.; Pogodin, V.P.

    1999-01-01

    The information concerning white patches observed on fuel cladding surfaces has been analytically treated. The analysis shows at least three kinds of the white patch appearance: bright white spots which appear to be loose corrosion product deposits disclosing corrosion pits upon spalling; indistinct streaks with separate pronounced spots 1-2 in dia. The spots seem to be thin superficial deposits; light-coloured dense uniform crud distributed over the surface of fuel claddings and fuel assembly jackets. (author)

  8. The Physics of Planetesimal Formation

    Science.gov (United States)

    Simon, Jacob; Armitage, Philip; Youdin, Andrew; Li, Rixin

    2015-12-01

    Planetesimals are the precursors to planets, and understanding their formation is an essential step towards developing a complete theory of planet formation. For small solid particles (e.g., dust grains) to coagulate into planetesimals, however, requires that these particles grow beyond centimeter sizes; with traditional coagulation physics, this is very difficult. The streaming instability, which is a clumping process akin to the pile-up of cars in a traffic jam, generates sufficiently high solid densities that the mutual gravity between the clumped particles eventually causes their collapse towards planetesimal mass and size scales. Exploring this transition from dust grains to planetesimals is still in its infancy but is extremely important if we want to understand the basics of planet formation. Here, I present a series of high resolution, first principles numerical simulations of potoplanetary disk gas and dust to study the clumping of particles via the streaming instability and the subsequent collapse towards planetesimals. These simulations have been employed to characterize the planetesimal population as a function of radius in protoplanetary disks. The results of these simulations will be crucial for planet formation models to correctly explain the formation and configuration of solar systems.

  9. Star formation and gas supply

    Science.gov (United States)

    Catinella, B.

    2016-06-01

    A detailed knowledge of how gas cycles in and around galaxies, and how it depends on galaxy properties such as stellar mass and star formation rate, is crucial to understand galaxy formation and evolution. We take advantage of the most sensitive surveys of cold gas in massive galaxies, GASS and COLD GASS, as well as of the state-of-the-art HI blind survey ALFALFA to investigate how molecular and atomic hydrogen reservoirs vary along and across the main sequence of star-forming galaxies.

  10. Understanding quantum physics

    International Nuclear Information System (INIS)

    Spillner, Vera

    2011-01-01

    This thesis presents a bundle definition for 'scientific understanding' through which the empirically equivalent interpretations of quantum mechanics can be evaluated with respect to the understanding they generate. The definition of understanding is based on a sufficient and necessary criterion, as well as a bundle of conditions - where a theory can be called most understandable whenever it fulfills the highest number of bundle criteria. Thereby the definition of understanding is based on the one hand on the objective number of criteria a theory fulfills, as well as, on the other hand, on the individual's preference of bundle criteria. Applying the definition onto three interpretations of quantum mechanics, the interpretation of David Bohm appears as most understandable, followed by the interpretation of Tim Maudlin and the Kopenhagen interpretation. These three interpretations are discussed in length in my thesis. (orig.)

  11. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... our information on Coping With Cancer helpful. Understanding Statistics About Survival Doctors estimate prognosis by using statistics that researchers have collected over many years about ...

  12. Close Formation Flight Control

    National Research Council Canada - National Science Library

    Proud, Andrew

    1999-01-01

    ... in the formation's drag is achieved. A controller, i.e., a formation-hold autopilot for the wing aircraft, is designed such that the formation's geometry is maintained in the face of lead aircraft maneuvers...

  13. Understanding cancer onset

    DEFF Research Database (Denmark)

    Veldhuis, Djuke

    2015-01-01

    Researchers in Malaysia analysed the genomes of people with a rare genetic disorder to better understand people’s predisposition to cancer across generations.......Researchers in Malaysia analysed the genomes of people with a rare genetic disorder to better understand people’s predisposition to cancer across generations....

  14. Understanding Menstrual Migraine.

    Science.gov (United States)

    Calhoun, Anne H

    2018-04-01

    Menstrual-related migraine is very prevalent, very disabling, yet very easy to manage given a good understanding of its cause. This article is intended to help with that understanding and to enable headache specialists to prescribe or create effective hormonal preventives of menstrual-related migraine. © 2018 American Headache Society.

  15. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... Questions to Ask about Your Diagnosis Research Understanding Cancer Prognosis Oncologist Anthony L. Back, M.D., a ... for provider care teams (PDF-210KB). Understanding Your Cancer Prognosis Video View this video on YouTube. Three ...

  16. Coevolutionary modeling in network formation

    KAUST Repository

    Al-Shyoukh, Ibrahim

    2014-12-03

    Network coevolution, the process of network topology evolution in feedback with dynamical processes over the network nodes, is a common feature of many engineered and natural networks. In such settings, the change in network topology occurs at a comparable time scale to nodal dynamics. Coevolutionary modeling offers the possibility to better understand how and why network structures emerge. For example, social networks can exhibit a variety of structures, ranging from almost uniform to scale-free degree distributions. While current models of network formation can reproduce these structures, coevolutionary modeling can offer a better understanding of the underlying dynamics. This paper presents an overview of recent work on coevolutionary models of network formation, with an emphasis on the following three settings: (i) dynamic flow of benefits and costs, (ii) transient link establishment costs, and (iii) latent preferential attachment.

  17. Modeling Chondrule Formation

    Science.gov (United States)

    Eisenhour, D. D.; Buseck, P. R.

    1995-09-01

    Over the last several decades considerable data on chondrule sizes, compositions, and textures has been collected [1]; experimental studies have greatly improved our understanding of the conditions required to produce chondrule compositions and textures [2]; and models of energetic nebular processes have provided insight into mechanisms by which chondrules may have formed [3]. While much work remains in each of these areas, the information presently available is sufficient to allow the construction of simple numerical models of chondrule formation. We have constructed a computer algorithm to investigate the consequences of forming chondrules under a variety of conditions. Variables that are considered include: 1) the mechanism of heating (e.g., EM radiation, aerodynamic drag, collisions with energetic particles), 2) peak chondrule temperature, 3) heat-source geometry, 4) pre-chondrule dust aggregate size distributions, 5) dust aggregate compositional distributions, 6) chondrule solidus and liquidus temperatures, 7) kinetic barriers to melting, and 8) the duration of heating. Output includes the size distributions and relative abundances of PO, PP, POP, BO, and NP chondrules. Given the uncertainties in the input variables, the primary purpose of the code is not to construct a single (and necessarily somewhat arbitrary) model of chondrule formation, but rather to elucidate the differences in chondrule properties associated with various sets of formation conditions. Results from a number of simulations using a variety of input parameters illustrate the importance of both composition and peak temperature on the proportion of porphyritic to non-porphyritic chondrules produced. Also apparent is the influence of the mechanism of heating on the relative size distributions of chondrule textural types. Results indicate that specific heating mechanisms require unique sets of associated conditions to account for the observed properties of chondrules. These unique sets of

  18. Understandings of 'Modelling'

    DEFF Research Database (Denmark)

    Andresen, Mette

    2007-01-01

    -authentic modelling is also linked with the potentials of exploration of ready-made models as a forerunner for more authentic modelling processes. The discussion includes analysis of an episode of students? work in the classroom, which serves to illustrate how concept formation may be linked to explorations of a non...

  19. Understanding Prenatal Tests

    Science.gov (United States)

    ... Navigation Bar Home Current Issue Past Issues Understanding Prenatal Tests Past Issues / Winter 2008 Table of Contents ... be done before pregnancy or at the first prenatal visit. If there is Rh incompatibility, treatments can ...

  20. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... Reporting & Auditing Grant Transfer Grant Closeout Contracts & Small Business Training Cancer Training at NCI (Intramural) Funding for ... disease will go for you is called prognosis. It can be hard to understand what prognosis means ...

  1. Understanding health insurance plans

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000879.htm Understanding health insurance plans To use the sharing features on this ... for you and your family. Types of Health Insurance Plans Depending on how you get your health ...

  2. Thermometers: Understand the Options

    Science.gov (United States)

    ... the options Thermometers come in a variety of styles. Understand the different types of thermometers and how ... MA. Fever in infants and children: Pathophysiology and management. http://www.uptodate.com/home. Accessed July 23, ...

  3. Understanding cardiovascular disease

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000759.htm Understanding cardiovascular disease To use the sharing features on this page, ... lead to heart attack or stroke. Types of Cardiovascular Disease Coronary heart disease (CHD) is the most common ...

  4. Tinnitus: Understanding the Facts

    Science.gov (United States)

    American Tinnitus Association Donate Become A Member Member Login Find A Provider Search form Search Menu Close Understanding The Facts Managing Your Tinnitus Research Toward A Cure About Us Initiatives News & ...

  5. Economics and International Understanding.

    Science.gov (United States)

    Chandra, Ramesh

    1983-01-01

    A methodology linking the teaching of economics to the promotion of international understanding is discussed. The content of a course dealing with the new international economic order is examined. (Author/RM)

  6. Understanding the New Economy.

    Science.gov (United States)

    Morrell, Louis R.

    2001-01-01

    Asserts that while the Nasdaq bubble did burst, the new economy is real and that failure to understand the rules of the digital economy can lead to substandard investment portfolio performance. Offers guidelines for higher education institutional investors. (EV)

  7. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... side effects from the cancer treatments you received. Video Series This video series offers the perspectives of ... care teams (PDF-210KB). Understanding Your Cancer Prognosis Video View this video on YouTube. Three cancer patients ...

  8. Understanding the DASH diet

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000784.htm Understanding the DASH diet To use the sharing features on this page, please enable JavaScript. The DASH diet is low in salt and rich in fruits, ...

  9. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... Managing Cancer Care Finding Health Care Services Costs & Medical Information Advance Directives Using Trusted Resources Understanding Cancer ... Care Finding Health Care Services Managing Costs and Medical Information Advance Directives Using Trusted Resources Cancer Types ...

  10. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... Care Finding Health Care Services Costs & Medical Information Advance Directives Using Trusted Resources Understanding Cancer What Is ... Health Care Services Managing Costs and Medical Information Advance Directives Using Trusted Resources Cancer Types Adolescents and ...

  11. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... Research Managing Cancer Care Finding Health Care Services Costs & Medical Information Advance Directives Using Trusted Resources Understanding ... Managing Cancer Care Finding Health Care Services Managing Costs and Medical Information Advance Directives Using Trusted Resources ...

  12. Understanding the Opioid Epidemic

    Science.gov (United States)

    ... Search Form Controls Cancel Submit Search The CDC Opioid Overdose Note: Javascript is disabled or is not ... message, please visit this page: About CDC.gov . Opioid Overdose Opioid Basics Understanding the Epidemic Commonly Used ...

  13. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... doctor to give you an accurate prognosis. Understanding the Difference Between Cure and Remission Cure means that ... about her colorectal cancer prognosis. Diving Out of the Dark View this video on YouTube. Andrew wants ...

  14. Understanding your hospital bill

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000881.htm Understanding your hospital bill To use the sharing features on this ... help you save money. Charges Listed on Your Hospital Bill A hospital bill will list the major ...

  15. Understanding Blood Pressure Readings

    Science.gov (United States)

    ... Artery Disease Venous Thromboembolism Aortic Aneurysm More Understanding Blood Pressure Readings Updated:Feb 19,2018 What do your ... this chart: English | Spanish | Traditional Chinese Enter Your Blood Pressure Systolic mm Hg (upper #) Diastolic mm Hg (lower #) ...

  16. Understanding Conflict?...Maybe!

    OpenAIRE

    Anthony P. Johnson

    2008-01-01

    The premise of this paper is the study in the field of conflict andconflict resolution and that conflict and conflict resolution are usefulareas of focus in order to better understand human behavior. Additionally,I will present data that will highlight the notion that conflict is not in itselfa bad thing and that conflict has the capability to be utilized as a vehiclefor understanding the many contradictions that are necessarily present inour efforts to be social beings.

  17. Understanding Family Diversity

    OpenAIRE

    Knowles, G

    2012-01-01

    This essential text will help students and those already working with children to understand both theoretically and practically, what may constitute a ‘family’. It explores how to build relationships with a child’s family to ensure early years settings and schools are working in partnership with children’s home environments, thereby supporting the best possible learning outcomes for children. It will help the reader to develop their skills, knowledge and understanding of their professional pr...

  18. The formation of cluster galaxies

    Science.gov (United States)

    Mancone, Conor L.

    2012-06-01

    In this work I sought to understand the formation and evolution of galaxies. Specifically, I studied three key aspects of galaxy formation: star formation, mass assembly, and structural evolution. Past research has shown that the formation of a galaxy is strongly coupled to its local environment (i.e. the local galaxy density). Therefore, I studied the evolution of cluster galaxies because clusters are the highest density environments that exist in the universe. In turn, the observational results found herein form a foundation upon which to test theories of galaxy formation in the densest environments. I used the latest sample of galaxy clusters from the Bootes region to measure the near-infrared luminosity function (NIR LF) of cluster galaxies from 0 1.3. I used deeper IRAC imaging to study the NIR LF of high redshift cluster galaxies (1 pulsating AGB stars, which are poorly understood observationally but contribute substantially to the NIR light of a stellar population. I also created the Python Galaxy Fitter (PyGFit), a program which measures PSF matched photometry from crowded imaging with disparate PSFs and resolutions. This enabled accurate measurement of spectral energy distributions (SEDs) in crowded cluster fields.

  19. Formate Formation and Formate Conversion in Biological Fuels Production

    Directory of Open Access Journals (Sweden)

    Bryan R. Crable

    2011-01-01

    Full Text Available Biomethanation is a mature technology for fuel production. Fourth generation biofuels research will focus on sequestering CO2 and providing carbon-neutral or carbon-negative strategies to cope with dwindling fossil fuel supplies and environmental impact. Formate is an important intermediate in the methanogenic breakdown of complex organic material and serves as an important precursor for biological fuels production in the form of methane, hydrogen, and potentially methanol. Formate is produced by either CoA-dependent cleavage of pyruvate or enzymatic reduction of CO2 in an NADH- or ferredoxin-dependent manner. Formate is consumed through oxidation to CO2 and H2 or can be further reduced via the Wood-Ljungdahl pathway for carbon fixation or industrially for the production of methanol. Here, we review the enzymes involved in the interconversion of formate and discuss potential applications for biofuels production.

  20. Formate Formation and Formate Conversion in Biological Fuels Production

    OpenAIRE

    Crable, Bryan R.; Plugge, Caroline M.; McInerney, Michael J.; Stams, Alfons J. M.

    2011-01-01

    Biomethanation is a mature technology for fuel production. Fourth generation biofuels research will focus on sequestering CO2 and providing carbon-neutral or carbon-negative strategies to cope with dwindling fossil fuel supplies and environmental impact. Formate is an important intermediate in the methanogenic breakdown of complex organic material and serves as an important precursor for biological fuels production in the form of methane, hydrogen, and potentially methanol. Formate is...

  1. Understanding Personality: Shakespeare, Jung, and Myers-Briggs.

    Science.gov (United States)

    Anderson, Sexton G.; Lauderdale, Margaret D.

    1985-01-01

    Applies the Myers-Briggs Type Indicator (MBTI) to help high school juniors understand their own personalities and the personalities of Shakespearean characters. Provides a format for interdisciplinary learning where teachers and counselors work together in the classroom. (LLL)

  2. The production of understanding.

    Science.gov (United States)

    Link, Bruce G

    2003-12-01

    While there is little doubt that sociological theory and research has had an important impact on the way people think about health and health care, mental health and medical sociologists are often confronted with challenges concerning the utility of the work that they do. Among the doubters are deans, funding agencies and family members. We are challenged by the ascendency of biological interpretations of human behaviors, by the incompatibility between the contextual view we prefer and the very strong individualistic orientation of our culture, and by the fact that we do not have an applied arm that trains the professionals who treat health and mental-health conditions. How do we respond to this challenge? The title of this paper gives a short answer: "The Production of Understanding." I propose that a powerful but under-recognized value of our work is the generation of explanations about health and mental health matters that help people understand the other side of an "us"/"them" divide. We produce understanding in a context in which misunderstanding is regularly constructed by powerful people who offer victim-blaming explanations for the circumstances experienced by people with less power. The production of understanding serves as an important counterbalance to this tendency. Our work shapes the way people think about problems related to health and mental health, limits the power of inaccurate victim-blaming accounts and provides understanding about why health and mental health are mal-distributed among people from different social circumstances.

  3. Understanding Data Structures

    Science.gov (United States)

    1975-02-01

    Data Division. Ibis task has hrrn left to the sub-schema processor as defined by the DBTG. A Frame (a sot of format logical rules) defines the DMLP...C^nclo h,\\r hrrn p.onrratet) to (lctrrniif>e tfie valuPS, relative to ACTl’itl, of ill MMM m the ITMS U’A NEXTLEVnUT««(lTMS) (■<,.|.. I ,K. \\i

  4. Understanding Tonal Languages

    Science.gov (United States)

    2013-04-01

    based on listening to vowels only 17 Table 12: Tone recognition rate by gender of speakers and listeners ............................... 18 Table 13...base syllable can be decomposed into an “INITIAL/FINAL” format very similar to the consonant/ vowel relations in English. “INITIAL” is the initial...consonant part of a syllable and “FINAL” is the vowel part but including optional medial or nasal ending. There are a total of 22 “INITIALs” and 41

  5. L3:PHI.CMD.P13.02 Support for CILC L1 Milestone Using STAR-CCM+

    Energy Technology Data Exchange (ETDEWEB)

    Slattery, Stuart R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gurecky, William L. [Univ. of Texas, Austin, TX (United States)

    2016-10-07

    This report documents work performed to support Consortium for the Advanced Simulation of LWRs (CASL) modeling of Chalk River Unidentified Deposit (CRUD) Induced Power Shift (CIPS) and CRUD Induced Local Corrosion (CILC) using the Cicada package. The work documented here is intended to complement current and future CIPS and CILC modeling activities in CASL. We provide tools for crud and corrosion-related simulation and analysis by developing a better understanding of the interplay between the coupled physics that describe the phenomena at different time and length scales. We intend to use these models to better inform future simulation capability and development.

  6. Understanding Sex for Sale

    DEFF Research Database (Denmark)

    This book Understanding Sex for Sale: Meanings and Moralities of Sexual Commerce is dedicated to the exploration of the ways in which sex prostitution, sex work or sex for sale are taken for granted by particularly looking at how the relation between sex and money is interpreted and enacted....... This interdisciplinary book aims to understand how prostitution, sex work or sex for sale are defined, delineated, contested and understood in different places and times. The book offers contributions from a number of scholars who, based on their on their own research, discuss on going theoretical issues and analytical...... challenges Some chapters focuses on how prostitution, sex work or sex for sale have been regulated by the authorities and what understandings this regulation builds on. Other chapters investigate the experiences of the sex workers and sex buyers asking how these actors adjust to or resist the categorisation...

  7. Student Perceptions of Formative Assessment in the Chemistry Classroom

    Science.gov (United States)

    Haroldson, Rachelle Ann

    2012-01-01

    Research on formative assessment has focused on the ways teachers implement and use formative assessment to check student understanding in order to guide their instruction. This study shifted emphasis away from teachers to look at how students use and perceive formative assessment in the science classroom. Four key strategies of formative…

  8. Understanding pastoral mobility

    DEFF Research Database (Denmark)

    Adriansen, Hanne Kirstine

    2008-01-01

    Based on a case study from Sahelian Senegal, this paper analyses how various actors perceive the importance of pastoral mobility and presents issues of importance for understanding the use of mobility among Fulani of Ferlo. One knowledge system is a scientific one, the 'new rangeland paradigm...... territory, which they consider their place, but are unwilling to employ large-scale mobility themselves. Mobility is not of importance for their ethnic identity and some use paid herders to care for their livestock. By looking at both knowledge systems, we achieve a better understanding of pastoral mobility...

  9. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... Your Diagnosis Research Understanding Cancer Prognosis Oncologist Anthony L. Back, M.D., a national expert on doctor- ... Centered Approach View this video on YouTube. Anthony L. Back, M.D., coaches other oncologists about how ...

  10. Understanding Inclusion in Cyprus

    Science.gov (United States)

    Mamas, Christoforos

    2013-01-01

    This paper provides a framework for understanding inclusion in Cyprus. The evidence base is the result of a six-month qualitative research study in five Cypriot mainstream primary schools. Despite the rhetoric in favour of inclusion, it seems that the Cypriot educational system is still highly segregating in its philosophy and does not fully…

  11. Understanding regime shifts

    DEFF Research Database (Denmark)

    Heymann, Matthias; Nielsen, Kristian Hvidtfelt

    ”. Danish wind power development is all the more surprising, as the innovation process in wind technology was carried to a large extent by non-academic craftsmen and political activists. Many features of this innovation story have been investigated and that research makes it possible to summarize...... the current understanding of the regime shift....

  12. Understanding land administration systems

    DEFF Research Database (Denmark)

    P. Williamson, Ian; Enemark, Stig; Wallace, Judy

    2008-01-01

    This paper introduces basic land administration theory and highlights four key concepts that are fundamental to understanding modern land administration systems. Readers may recall the first part of the paper in October issue of Coordinates. Here is the concluding part that focuses on the changing...

  13. Understanding the bubbles

    DEFF Research Database (Denmark)

    Turcan, Romeo V.

    all boils down to the role pricing plays vis-à-vis the emergence of a new venture and its perceived value. Being in the midst of the global economic crisis provides us with a unique opportunity to refine the proposed model, especially by understanding its temporal and contextual boundaries....

  14. Teachers' Understandings of Probability

    Science.gov (United States)

    Liu, Yan; Thompson, Patrick

    2007-01-01

    Probability is an important idea with a remarkably wide range of applications. However, psychological and instructional studies conducted in the last two decades have consistently documented poor understanding of probability among different populations across different settings. The purpose of this study is to develop a theoretical framework for…

  15. Understanding Ocean Acidification

    Science.gov (United States)

    National Oceanic and Atmospheric Administration, 2011

    2011-01-01

    This curriculum module is designed for students who are taking high school chemistry. Students should already have some experience with the following: (1) Understanding and reading the pH scale; (2) Knowledge of the carbon cycle; (3) Using scientific notation to express large and small values; and (4) Reading chemical equations. This curriculum…

  16. Phun Week: Understanding Physiology

    Science.gov (United States)

    Limson, Mel; Matyas, Marsha Lakes

    2009-01-01

    Topics such as sports, exercise, health, and nutrition can make the science of physiology relevant and engaging for students. In addition, many lessons on these topics, such as those on the cardiovascular, respiratory, and digestive systems, align with national and state life science education standards. Physiology Understanding Week (PhUn…

  17. Understanding Organizational Advantage

    DEFF Research Database (Denmark)

    Stea, Diego; Linder, Stefan; Foss, Nicolai Juul

    2015-01-01

    The attention-based view (ABV) of the firm highlights the role of decision makers’ attention in firm behavior. The ABV vastly improves our understanding of decision makers’ focus of attention; how that focus is situated in an organization’s procedural and communication channels; and how the distr......The attention-based view (ABV) of the firm highlights the role of decision makers’ attention in firm behavior. The ABV vastly improves our understanding of decision makers’ focus of attention; how that focus is situated in an organization’s procedural and communication channels; and how...... the distribution of the focus of attention among decision makers participating in those procedural and communication channels affects their understanding of a situation, their motivation to act, and, ultimately, their behavior. Significant progress has been made in recent years in refining and extending the ABV....... However, the role of individual differences in the capacity to read other people’s desires, intentions, knowledge, and beliefs that is, the theory of mind (ToM) has remained on the sidelines. The ToM is a natural complement to the ABV. In this study, we explore how the ToM allows for an understanding...

  18. Understanding ADHD through entification

    DEFF Research Database (Denmark)

    Nielsen, Mikka

    with adults diagnosed with ADHD, I illustrate how the process of entification (transforming a trait, temperament, emotion, or some other psychological phenomenon into a thing or agent) can be a way to understand, accept and handle the symptoms of ADHD. In this context, ADHD is perceived on the one hand...

  19. Measuring Spreadsheet Formula Understandability

    NARCIS (Netherlands)

    Hermans, F.F.J.; Pinzger, M.; Van Deursen, A.

    2012-01-01

    Spreadsheets are widely used in industry, because they are flexible and easy to use. Often they are used for business-critical applications. It is however difficult for spreadsheet users to correctly assess the quality of spreadsheets, especially with respect to the understandability.

  20. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... 1-800-4-CANCER Live Chat Publications Dictionary Menu Contact Dictionary Search About Cancer Causes and Prevention ... source and a link to this page included, e.g., “Understanding Cancer Prognosis was originally published by ...

  1. Text understanding for computers

    NARCIS (Netherlands)

    Kenter, T.M.

    2017-01-01

    A long-standing challenge for computers communicating with humans is to pass the Turing test, i.e., to communicate in such a way that it is impossible for humans to determine whether they are talking to a computer or another human being. The field of natural language understanding — which studies

  2. Interviewing to Understand Strengths

    Science.gov (United States)

    Hass, Michael R.

    2018-01-01

    Interviewing clients about their strengths is an important part of developing a complete understanding of their lives and has several advantages over simply focusing on problems and pathology. Prerequisites for skillfully interviewing for strengths include the communication skills that emerge from a stance of not knowing, developing a vocabulary…

  3. Prediction of tar ball formation

    International Nuclear Information System (INIS)

    Khelifa, A.; Gamble, L.

    2006-01-01

    The presence of small tar balls ranging in size from less than a millimetre to 60 centimetres have been observed during cleanup assessment operations following accidental oil spills on water. The tar balls are composed of heavy oil residues and suspended particulate matter (SPM) from the water column. They can be found on shorelines, settled on the seafloor and floating at or near the water surface. Their abundance on the shorelines varies from site to site and depends on the conditions of the spill and mixing conditions. Aggregation between SPM and micro-sized oil droplets occurs naturally in coastal waters and enhances the dispersion of spilled oil. Although tar balls are among the important end states of spilled oil in the marine environment, no model exists to estimate the percentage of the spilled oil that becomes tar balls. This paper offered some insight into the modeling of tar ball formation. Current modeling understanding of oil-SPM aggregate formation was used to predict tar ball formation. The formation of oil droplets was examined with respect to a range of conditions under which the formation of large droplets is expected. The role of aggregation was then presented to demonstrate the effects of concentration and type of SPM on the buoyancy of tar balls. Good agreement was found between modeling results and field data reported in the literature regarding the size and density of tar balls. Oil viscosity and mixing energy were found to be the main factors controlling the formation of tar balls. The aggregation of tar balls with SPM and shoreline material results in significant increases or decreases in density, depending on the type and concentration of SPM. 42 refs., 2 tabs., 6 figs

  4. The Format Dilemma.

    Science.gov (United States)

    Oder, Norman

    2002-01-01

    Reports results of a survey of public libraries that investigated trends in audiovisual materials. Highlights include format issues; audiobooks; media budgets for various formats; video collections; DVDs; circulation; collection sizes; music CDs; and future possibilities. (LRW)

  5. Understanding Games as Played

    DEFF Research Database (Denmark)

    Leino, Olli Tapio

    2009-01-01

    Researchers interested in player’s experience would assumedly, across disciplines, agree that the goal behind enquiries into player’s experience is to understand the how games’ features end up affecting the player’s experience. Much of the contemporary interdisciplinary research into player......’s experience leans toward the empirical-scientific, in the forms (neuro)psychology, sociology and cognitive science, to name a few. In such approaches, for example demonstrating correlation between physiological symptoms and an in-game event may amount to ‘understanding’. However, the experience of computer...... game play is a viable topic also for computer game studies within the general tradition of humanities. In such context, the idea of ‘understanding an experience’ invites an approach focusing on the experienced significance of events and objects within computer game play. This focus, in turn, suggests...

  6. Understanding Video Games

    DEFF Research Database (Denmark)

    Heide Smith, Jonas; Tosca, Susana Pajares; Egenfeldt-Nielsen, Simon

    From Pong to PlayStation 3 and beyond, Understanding Video Games is the first general introduction to the exciting new field of video game studies. This textbook traces the history of video games, introduces the major theories used to analyze games such as ludology and narratology, reviews...... the economics of the game industry, examines the aesthetics of game design, surveys the broad range of game genres, explores player culture, and addresses the major debates surrounding the medium, from educational benefits to the effects of violence. Throughout the book, the authors ask readers to consider...... larger questions about the medium: * What defines a video game? * Who plays games? * Why do we play games? * How do games affect the player? Extensively illustrated, Understanding Video Games is an indispensable and comprehensive resource for those interested in the ways video games are reshaping...

  7. Understanding Video Games

    DEFF Research Database (Denmark)

    Heide Smith, Jonas; Tosca, Susana Pajares; Egenfeldt-Nielsen, Simon

    From Pong to PlayStation 3 and beyond, Understanding Video Games is the first general introduction to the exciting new field of video game studies. This textbook traces the history of video games, introduces the major theories used to analyze games such as ludology and narratology, reviews...... larger questions about the medium: * What defines a video game? * Who plays games? * Why do we play games? * How do games affect the player? Extensively illustrated, Understanding Video Games is an indispensable and comprehensive resource for those interested in the ways video games are reshaping...... entertainment and society. A companion website (www.routledge.com/textbooks/9780415977210) features student resources including discussion questions for each chapter, a glossary of key terms, a video game timeline, and links to other video game studies resources for further study....

  8. Understanding China's Transformations

    DEFF Research Database (Denmark)

    Li, Xing

    The objective of this paper is to offer a framework of understanding the dialectical nexus between China's internal evolutions and the external influences with a focus on the century-long "challenge-response" dynamism. That is to explore how external factors helped shaping China's internal...... transformations, i.e. how generations of Chinese have been struggling in responding to the external challenges and attempting to sinicize external political ideas in order to change China from within. Likewise, it is equally important to understand how China's inner transformation contributed to reshaping...... the world. Each time, be it China's dominance or decline, the capitalist world system has to adjust and readjust itself to the opportunities and constraints brought about by the "China factors"....

  9. Intention understanding in autism.

    Directory of Open Access Journals (Sweden)

    Sonia Boria

    Full Text Available When we observe a motor act (e.g. grasping a cup done by another individual, we extract, according to how the motor act is performed and its context, two types of information: the goal (grasping and the intention underlying it (e.g. grasping for drinking. Here we examined whether children with autistic spectrum disorder (ASD are able to understand these two aspects of motor acts. Two experiments were carried out. In the first, one group of high-functioning children with ASD and one of typically developing (TD children were presented with pictures showing hand-object interactions and asked what the individual was doing and why. In half of the "why" trials the observed grip was congruent with the function of the object ("why-use" trials, in the other half it corresponded to the grip typically used to move that object ("why-place" trials. The results showed that children with ASD have no difficulties in reporting the goals of individual motor acts. In contrast they made several errors in the why task with all errors occurring in the "why-place" trials. In the second experiment the same two groups of children saw pictures showing a hand-grip congruent with the object use, but within a context suggesting either the use of the object or its placement into a container. Here children with ASD performed as TD children, correctly indicating the agent's intention. In conclusion, our data show that understanding others' intentions can occur in two ways: by relying on motor information derived from the hand-object interaction, and by using functional information derived from the object's standard use. Children with ASD have no deficit in the second type of understanding, while they have difficulties in understanding others' intentions when they have to rely exclusively on motor cues.

  10. Understanding nuclear issues

    Energy Technology Data Exchange (ETDEWEB)

    Marx, G. [Department of Atomic Physics, Eoetvoes Univ., Budapest (Hungary)

    1999-09-01

    In our days technological progress for the benefit of society is slowed down by the fact that common citizens (opinion-forming media reporters, journalists, furthermore elected decision-makers) are underinformed about basic numerical facts concerning harms and benefits of high technology. Here a comparative risk study is presented about smoking, ozone hole, global warming, and ionizing radiation. This approach has turned out to be successful in educating the youth in Hungary; because school-going teenagers do understand numbers. (author)

  11. Understanding the spermatozoon.

    Science.gov (United States)

    Neri, Queenie V; Hu, Jennifer; Rosenwaks, Zev; Palermo, Gianpiero D

    2014-01-01

    The former perception of the spermatozoon as a delivery device of the male genome has been expanded to include a new understanding of the cell's complex role in fertilization. Once the spermatozoon reaches the oocyte, it triggers egg activation and orchestrates the stages of pre- and post-fertilization in a preprogrammed pattern while tapping the oocyte's resources in an effort to generate a new life.

  12. Understanding Mediation Support

    OpenAIRE

    Lanz, David; Pring, Jamie; von Burg, Corinne; Zeller, Mathias

    2017-01-01

    Recent decades have witnessed increasing institutionalization of mediation support through the establishment of mediation support structures (MSS) within foreign ministries and secretariats of multilateral organizations. This study sheds light on this trend and aims to better understand the emergence, design and development of different MSS. This study analyzes six MSS, namely those established in the United Nations (UN), the Organization for Security and Co-operation in Europe (OSCE), the Eu...

  13. Understanding nuclear issues

    International Nuclear Information System (INIS)

    Marx, G.

    1999-01-01

    In our days technological progress for the benefit of society is slowed down by the fact that common citizens (opinion-forming media reporters, journalists, furthermore elected decision-makers) are underinformed about basic numerical facts concerning harms and benefits of high technology. Here a comparative risk study is presented about smoking, ozone hole, global warming, and ionizing radiation. This approach has turned out to be successful in educating the youth in Hungary; because school-going teenagers do understand numbers. (author)

  14. Image Understanding Research

    Science.gov (United States)

    1980-03-31

    Numerlues en Sciences Physiques et Economiques , Collection Methode Mathematiques de l’Informatique, Dunod, 1976. 47 26. P. Saint-Pierre, "Etude Theorique et...overlap since adjacent linear features are being presented. References 1. S. Rubin, "The ARGOS Image Understanding System," Ph.D. thesis, Computer Science ...Techniques," TR 480, Computer Science Center, University of Maryland, September i979. 5. Davis, Larry S. and Azriel Rosenfeld, "Hierarchical Relaxation for

  15. Formate Formation and Formate Conversion in Biological Fuels Production

    NARCIS (Netherlands)

    Crable, B.R.; Plugge, C.M.; McInerney, M.J.; Stams, A.J.M.

    2011-01-01

    Biomethanation is a mature technology for fuel production. Fourth generation biofuels research will focus on sequestering CO2 and providing carbon-neutral or carbon-negative strategies to cope with dwindling fossil fuel supplies and environmental impact. Formate is an important intermediate in the

  16. Singularities formation, structure, and propagation

    CERN Document Server

    Eggers, J

    2015-01-01

    Many key phenomena in physics and engineering are described as singularities in the solutions to the differential equations describing them. Examples covered thoroughly in this book include the formation of drops and bubbles, the propagation of a crack and the formation of a shock in a gas. Aimed at a broad audience, this book provides the mathematical tools for understanding singularities and explains the many common features in their mathematical structure. Part I introduces the main concepts and techniques, using the most elementary mathematics possible so that it can be followed by readers with only a general background in differential equations. Parts II and III require more specialised methods of partial differential equations, complex analysis and asymptotic techniques. The book may be used for advanced fluid mechanics courses and as a complement to a general course on applied partial differential equations.

  17. Othering, identity formation and agency

    Directory of Open Access Journals (Sweden)

    Sune Qvotrup Jensen

    2011-10-01

    Full Text Available The article examines the potentials of the concept of othering to describe identity formation among ethnic minorities. First, it outlines the history of the concept, its contemporary use, as well as some criticisms. Then it is argued that young ethnic minority men in Denmark are subject to intersectional othering, which contains elements of exoticist fascination of the other. On the basis of ethnographic material, it is analysed how young marginalized ethnic minority men react to othering. Two types of reactions are illustrated: 1 capitalization on being positioned as the other, and 2 refusing to occupy the position of the other by disidentification and claims to normality. Finally, it is argued that the concept of othering is well suited for understanding the power structures as well as the historic symbolic meanings conditioning such identity formation, but problematic in terms of agency.

  18. Shutdown radiation level and man-rem control for water cooled reactors

    International Nuclear Information System (INIS)

    Cripps, S.J.; Regan, J.D.

    1978-01-01

    The importance of controlling the formation and subsequent deposition of active corrosion products (crud) is highlighted as a method of reducing occupational exposure. A semi-empirical model is described and used to predict the effectiveness of various methods of crud control. The relative merits of reactor coolant clean-up techniques including ion-exchange and electromagnetic filtration are assessed in terms of man-rem savings and associated cost penalties. (author)

  19. The Black Hole Formation Probability

    Science.gov (United States)

    Clausen, Drew; Piro, Anthony L.; Ott, Christian D.

    2015-02-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. We present an initial exploration of the probability that a star will make a BH as a function of its ZAMS mass, P BH(M ZAMS). Although we find that it is difficult to derive a unique P BH(M ZAMS) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P BH(M ZAMS) changes with these various observational and theoretical uncertainties. We anticipate that future studies of Galactic BHs and theoretical studies of core collapse will refine P BH(M ZAMS) and argue that this framework is an important new step toward better understanding BH formation. A probabilistic description of BH formation will be useful as input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment.

  20. THE BLACK HOLE FORMATION PROBABILITY

    International Nuclear Information System (INIS)

    Clausen, Drew; Piro, Anthony L.; Ott, Christian D.

    2015-01-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. We present an initial exploration of the probability that a star will make a BH as a function of its ZAMS mass, P BH (M ZAMS ). Although we find that it is difficult to derive a unique P BH (M ZAMS ) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P BH (M ZAMS ) changes with these various observational and theoretical uncertainties. We anticipate that future studies of Galactic BHs and theoretical studies of core collapse will refine P BH (M ZAMS ) and argue that this framework is an important new step toward better understanding BH formation. A probabilistic description of BH formation will be useful as input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment

  1. Exploring the value of usability feedback formats

    DEFF Research Database (Denmark)

    Nørgaard, Mie; Hornbæk, Kasper Anders Søren

    2009-01-01

    presented using five feedback formats. Our usability findings comprise 35 problems and 5 positive comments. Data suggest that feedback serves multiple purposes. Initially, feedback must convince developers about the relevance of a problem and convey an understanding of this. Feedback must next be easy...... working with the feedback to address the usability problems, there were no significant differences among the developers' ratings of the value of the different formats. This suggests that all of the formats may serve equally well as reminders in later stages of working with usability problems...

  2. Controlling selectivities in CO2 reduction through mechanistic understanding

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiang; Shi, Hui; Szanyi, János

    2017-09-11

    Catalytic CO2 conversion to energy carriers and intermediates is of utmost importance to energy and environmental goals. However, the lack of fundamental understanding of the reaction mechanism renders designing a selective catalyst inefficient. We performed operando FTIR/SSITKA experiments to understand the correlation between the kinetics of product formation and that of surface species conversion during CO2 reduction over Pd/Al2O3 catalysts. We found that the rate-determining step for CO formation is the conversion of adsorbed formate, while that for CH4 formation is the hydrogenation of adsorbed carbonyl. The balance of the hydrogenation kinetics between adsorbed formates and carbonyls governs the selectivities to CH4 and CO. We demonstrated how this knowledge can be used to design catalysts to achieve high selectivities to desired products.

  3. Understanding Galaxy Cluster MKW10

    Science.gov (United States)

    Sanders, Tim; Henry, Swain; Coble, Kimberly A.; Rosenberg, Jessica L.; Koopmann, Rebecca A.

    2015-01-01

    As part of the Undergraduate ALFALFA Team (UAT), we are studying the galaxy cluster MKW 10 (RA = 175.454, Dec = 10.306, z ~ 0.02), a poor cluster with a compact core in which tidal interactions have occurred. This cluster has been observed in HI and Hα. We used SDSS and NED to search for optical counterparts. By comparing data at multiple wavelengths, we hope to understand the structure, environment, and star formation history of this cluster. Following the techniques of others involved in the groups project and using the program TOPCAT to manipulate the data, we explored both the spatial and velocity distributions to determine cluster membership. We have determined that this cluster consists of 11 galaxies, mostly spiral in shape. Chicago State University is new the UAT and we began our work after taking part in the winter workshop at Arecibo.This work was supported by: Undergraduate ALFALFA Team NSF Grant AST-1211005 and the Illinois Space Grant Consortium.

  4. Understanding Interest Rate Volatility

    DEFF Research Database (Denmark)

    Volker, Desi

    with and without stochastic volatility to capture the main stylized features of U.S. interest rates. The third essay, \\Variance Risk Premia in the Interest Rate Swap Market", investigates the time-series and cross-sectional properties of the compensation demanded for holding interest rate variance risk. The essays...... are self-contained and can be read independently. There is however a common thread in the themes covered as all essays focus on the understanding of interest rate volatility, its time-variation and main determinants....

  5. Understanding Ebola Virus Transmission

    Directory of Open Access Journals (Sweden)

    Seth Judson

    2015-02-01

    Full Text Available An unprecedented number of Ebola virus infections among healthcare workers and patients have raised questions about our understanding of Ebola virus transmission. Here, we explore different routes of Ebola virus transmission between people, summarizing the known epidemiological and experimental data. From this data, we expose important gaps in Ebola virus research pertinent to outbreak situations. We further propose experiments and methods of data collection that will enable scientists to fill these voids in our knowledge about the transmission of Ebola virus.

  6. Understanding Computational Bayesian Statistics

    CERN Document Server

    Bolstad, William M

    2011-01-01

    A hands-on introduction to computational statistics from a Bayesian point of view Providing a solid grounding in statistics while uniquely covering the topics from a Bayesian perspective, Understanding Computational Bayesian Statistics successfully guides readers through this new, cutting-edge approach. With its hands-on treatment of the topic, the book shows how samples can be drawn from the posterior distribution when the formula giving its shape is all that is known, and how Bayesian inferences can be based on these samples from the posterior. These ideas are illustrated on common statistic

  7. Understanding Homicide-Suicide.

    Science.gov (United States)

    Knoll, James L

    2016-12-01

    Homicide-suicide is the phenomenon in which an individual kills 1 or more people and commits suicide. Research on homicide-suicide has been hampered by a lack of an accepted classification scheme and reliance on media reports. Mass murder-suicide is gaining increasing attention particularly in the United States. This article reviews the research and literature on homicide-suicide, proposing a standard classification scheme. Preventive methods are discussed and sociocultural factors explored. For a more accurate and complete understanding of homicide-suicide, it is argued that future research should use the full psychological autopsy approach, to include collateral interviews. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Understanding quantum phase transitions

    CERN Document Server

    Carr, Lincoln

    2010-01-01

    Quantum phase transitions (QPTs) offer wonderful examples of the radical macroscopic effects inherent in quantum physics: phase changes between different forms of matter driven by quantum rather than thermal fluctuations, typically at very low temperatures. QPTs provide new insight into outstanding problems such as high-temperature superconductivity and display fundamental aspects of quantum theory, such as strong correlations and entanglement. Over the last two decades, our understanding of QPTs has increased tremendously due to a plethora of experimental examples, powerful new numerical meth

  9. Understanding Teen UX

    DEFF Research Database (Denmark)

    Fitton, Daniel; Iversen, Ole Sejer; Bell, Beth

    2014-01-01

    needs to be understood about this population, from a UX perspective. The theme of this workshop is Building a Bridge to the Future and the aim is to gather together academics and UX practitioners, interested in teen users specifically, in order to discuss experiences, understandings, insights...... and methods that we can use to comprehend teen UX now and explore how this may lead to the creation of better interactive products in the future. The workshop will also foster new collaborations, and define new research agendas to grow the research and literature in this area....

  10. Understanding DSGE models

    CERN Document Server

    Costa Junior, Celso Jose

    2016-01-01

    While the theoretical development of DSGE models is not overly difficult to understand, practical application remains somewhat complex. The literature on this subject has some significant obscure points. This book can be thought of, firstly, as a tool to overcome initial hurdles with this type of modeling. Secondly, by showcasing concrete applications, it aims to persuade incipient researchers to work with this methodology. In principle, this is not a book on macroeconomics in itself, but on tools used in the construction of this sort of models. It strives to present this technique in a detail

  11. Formation Flying Concept Issues

    Directory of Open Access Journals (Sweden)

    M. V. Palkin

    2015-01-01

    Full Text Available The term “formation flying” implies coordinated movement of at least two satellites on coplanar and non-coplanar orbits with a maximum distance between them being much less than the length of the orbit. Peculiarities of formation flying concept also include:- automatic coordination of satellites;- sub-group specialization of formation flying satellites;- equipment and data exchange technology unification in each specialized group or subgroup.Formation flying satellites can be classified according to the configuration stability level (order (array, cluster («swarm», intergroup specialization rules («central satellite», «leader», «slave», manoeuvrability («active» and «passive» satellites.Tasks of formation flying include:- experiments with payload, distributed in formation flying satellites;- various near-earth space and earth-surface research;- super-sized aperture antenna development;- land-based telescope calibration;- «space advertisement» (earth-surface observable satellite compositions of a logotype, word, etc.;- orbital satellite maintenance, etc.Main issues of formation flying satellite system design are:- development of an autonomous satellite group manoeuvring technology;- providing a sufficient characteristic velocity of formation flying satellites;- ballistic and navigation maintenance for satellite formation flying;- technical and economic assessment of formation flying orbital delivery and deployment;- standardization, unification, miniaturization and integration of equipment;- intergroup and intersatellite function redistribution.

  12. From Sermon Formation to Preacher Formation

    DEFF Research Database (Denmark)

    Gaarden, Marianne

    2016-01-01

    today is less about exercising the authority of an office and more about embodying authenticity. I argue that traditional homiletic education can benefit from implementing a learner-centered approach to teaching moving from sermon formation towards preacher formation, in order to develop and train...... judged, evaluated, or critiqued. In this paper, I explain how a learner-centered approach to education works in practice and show how pastors experience the teaching method and the congregations’ positive response to their improvements. I shall present the results of a focus-group interview with pastors...

  13. Understanding medical device regulation.

    Science.gov (United States)

    Galgon, Richard E

    2016-12-01

    The purpose of this article is to provide a structural and functional understanding of the systems used for the regulation of medical devices in the USA and European Union (EU). Safe and effective anesthesia care depends heavily on medical devices, including simple, low risk devices to complex life-supporting and life-sustaining devices. In the USA and EU, the Food and Drug Administration and European Commission, respectively, provide regulatory oversight to ensure medical devices are reasonably safe and effective when used for their intended purposes. Unfortunately, practicing anesthesiologists generally have little or no understanding of how medical devices are regulated, nor do they have sufficient knowledge of available adverse event reporting systems. The US and EU medical device regulatory systems are similar in many ways, but differ in important ways too, which impacts the afforded level of safety and effectiveness assurance. In both systems, medical devices are classified and regulated on a risk basis, which fundamentally differs from drug regulation, where uniform requirements are imposed. Anesthesia providers must gain knowledge of these systems and be active players in both premarket and postmarket activities, particularly with regard to vigilance and adverse event/device failure reporting.

  14. Understanding Lustre Internals

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Feiyi [ORNL; Oral, H Sarp [ORNL; Shipman, Galen M [ORNL; Drokin, Oleg [ORNL; Wang, Di [ORNL; Huang, He [ORNL

    2009-04-01

    Lustre was initiated and funded, almost a decade ago, by the U.S. Department of Energy (DoE) Office of Science and National Nuclear Security Administration laboratories to address the need for an open source, highly-scalable, high-performance parallel filesystem on by then present and future supercomputing platforms. Throughout the last decade, it was deployed over numerous medium-to-large-scale supercomputing platforms and clusters, and it performed and met the expectations of the Lustre user community. As it stands at the time of writing this document, according to the Top500 list, 15 of the top 30 supercomputers in the world use Lustre filesystem. This report aims to present a streamlined overview on how Lustre works internally at reasonable details including relevant data structures, APIs, protocols and algorithms involved for Lustre version 1.6 source code base. More importantly, it tries to explain how various components interconnect with each other and function as a system. Portions of this report are based on discussions with Oak Ridge National Laboratory Lustre Center of Excellence team members and portions of it are based on our own understanding of how the code works. We, as the authors team bare all responsibilities for all errors and omissions in this document. We can only hope it helps current and future Lustre users and Lustre code developers as much as it helped us understanding the Lustre source code and its internal workings.

  15. Mantle dynamics following supercontinent formation

    Science.gov (United States)

    Heron, Philip J.

    This thesis presents mantle convection numerical simulations of supercontinent formation. Approximately 300 million years ago, through the large-scale subduction of oceanic sea floor, continental material amalgamated to form the supercontinent Pangea. For 100 million years after its formation, Pangea remained relatively stationary, and subduction of oceanic material featured on its margins. The present-day location of the continents is due to the rifting apart of Pangea, with supercontinent dispersal being characterized by increased volcanic activity linked to the generation of deep mantle plumes. The work presented here investigates the thermal evolution of mantle dynamics (e.g., mantle temperatures and sub-continental plumes) following the formation of a supercontinent. Specifically, continental insulation and continental margin subduction are analyzed. Continental material, as compared to oceanic material, inhibits heat flow from the mantle. Previous numerical simulations have shown that the formation of a stationary supercontinent would elevate sub-continental mantle temperatures due to the effect of continental insulation, leading to the break-up of the continent. By modelling a vigorously convecting mantle that features thermally and mechanically distinct continental and oceanic plates, this study shows the effect of continental insulation on the mantle to be minimal. However, the formation of a supercontinent results in sub-continental plume formation due to the re-positioning of subduction zones to the margins of the continent. Accordingly, it is demonstrated that continental insulation is not a significant factor in producing sub-supercontinent plumes but that subduction patterns control the location and timing of upwelling formation. A theme throughout the thesis is an inquiry into why geodynamic studies would produce different results. Mantle viscosity, Rayleigh number, continental size, continental insulation, and oceanic plate boundary evolution are

  16. Stages of ores formation

    International Nuclear Information System (INIS)

    Khasanov, A.Kh.

    1988-01-01

    Deposit formation (especially endogenous) is the complicated, multi-stage and long process. Establishment of deposit formation succession, age-specific correlations of minerals and aggregates have a high importance at solving genetic questions. Studying of minerals correlations and mineral aggregates, succession of their crystallization and other observations let restore the history of deposit formation, pick up in it different on duration and physical and chemical conditions stages

  17. Understanding engineering mathematics

    CERN Document Server

    Cox, Bill

    2001-01-01

    * Unique interactive style enables students to diagnose their strengths and weaknesses and focus their efforts where needed* Ideal for self-study and tutorial work, building from an initially supportive approach to the development of independent learning skills * Free website includes solutions to all exercises, additional topics and applications, guide to learning mathematics, and practice materialStudents today enter engineering courses with a wide range of mathematical skills, due to the many different pre-university qualifications studied. Bill Cox''s aim is for students to gain a thorough understanding of the maths they are studying, by first strengthening their background in the essentials of each topic. His approach allows a unique self-paced study style, in which students Review their strengths and weaknesses through self-administered diagnostic tests, then focus on Revision where they need it, to finally Reinforce the skills required.The book is structured around a highly successful ''transition'' ma...

  18. From understanding to participation

    DEFF Research Database (Denmark)

    Raudaskoski, Pirkko Liisa

    2013-01-01

    The paper presents some methodological considerations around the topic of the AFinLA 2012 Autumn Symposium: Multimodal discourses of participation. The aim is to shed theoretical and analytical light on embodied participation in material settings. The research is placed in a relational perspective...... in which entities (for example, the world, culture, society, organization and identities) emerge through entangled, layered practices in concrete circumstances. Understanding is not treated as a philosophical puzzle or as a purely linguistic phenomenon. Rather, it is conceptualized as an embodied......, multimodal process in which language together with bodily senses (vision, hearing, touch, smell and taste) and a sense of place contribute to a phenomenon being recognized (as shared). Participation can result in inclusion or exclusion, a claim which is discussed with the help of a pilot study from...

  19. Understanding land administration systems

    DEFF Research Database (Denmark)

    P. Williamson, Ian; Enemark, Stig; Wallace, Judy

    2008-01-01

    This paper introduces basic land administration theory and highlights four key concepts that are fundamental to understanding modern land administration systems - firstly the land management paradigm and its influence on the land administration framework, secondly the role that the cadastre plays...... in contributing to sustainable development, thirdly the changing nature of ownership and the role of land markets, and lastly a land management vision that promotes land administration in support of sustainable development and spatial enablement of society. We present here the first part of the paper. The second...... part focuses on the changing  role of ownership and the role of land markets, and a land management vision will be published in November issue of Coordinates. Udgivelsesdato: Oktober...

  20. Understanding medical symptoms

    DEFF Research Database (Denmark)

    Malterud, Kirsti; Guassora, Ann Dorrit Kristiane; Graungaard, Anette Hauskov

    2015-01-01

    perspectives deal with how symptom perception occurs when any kind of altered balance brings forward a bodily attention. Corporeality is brought to explicit awareness and perceived as sensations. Jesper Hoffmeyer’s biosemiotic perspectives provide access to how signs are interpreted to attribute meaning......The aim of this article is to present a conceptual review and analysis of symptom understanding. Subjective bodily sensations occur abundantly in the normal population and dialogues about symptoms take place in a broad range of contexts, not only in the doctor’s office. Our review of symptom...... is a social and relational phenomenon of containment, and regulating the situation where the symptoms originate implies adjusting containment. Discourse analysis, as presented by Jonathan Potter and Margaret Wetherell, provides a tool to notice the subtle ways in which language orders perceptions and how...

  1. Understanding philosophical animal

    Directory of Open Access Journals (Sweden)

    Popović Una

    2010-01-01

    Full Text Available In this paper, inspired by the Predrag Krstić's book Philosophical Animal author is trying to find hers way through a broad and complex web of philosophies and roles that different animals play in them. The main question is how to understand philosophy itself in a present day context, which philosophy is supposed to think and rethink through. Animals as presented in concepts, more precisely philosophical contexts, open one interesting and innovative way to deal with this question, balancing between tradition of philosophy and its presence, structure of philosophical arguments and questioning of language of philosophy, abstract and individual. In this frame philosopher as the true philosophical animal is revealed as the main symbol that requires analysis in his philosophical strategies.

  2. Towards better process understanding

    DEFF Research Database (Denmark)

    Matero, Sanni Elina; van der Berg, Franciscus Winfried J; Poutiainen, Sami

    2013-01-01

    The manufacturing of tablets involves many unit operations that possess multivariate and complex characteristics. The interactions between the material characteristics and process related variation are presently not comprehensively analyzed due to univariate detection methods. As a consequence......, current best practice to control a typical process is to not allow process-related factors to vary i.e. lock the production parameters. The problem related to the lack of sufficient process understanding is still there: the variation within process and material properties is an intrinsic feature...... and cannot be compensated for with constant process parameters. Instead, a more comprehensive approach based on the use of multivariate tools for investigating processes should be applied. In the pharmaceutical field these methods are referred to as Process Analytical Technology (PAT) tools that aim...

  3. Understanding climatic change

    International Nuclear Information System (INIS)

    Fellous, J.L.; Gautier, C.; Andre, J.C.; Balstad, R.; Boucher, O.; Brasseur, G.; Chahine, M.T.; Chanin, M.L.; Ciais, P.; Corell, W.; Duplessy, J.C.; Hourcade, J.C.; Jouzel, J.; Kaufman, Y.J.; Laval, K.; Le Treut, H.; Minster, J.F.; Moore, B. III; Morel, P.; Rasool, S.I.; Remy, F.; Smith, R.C.; Somerville, R.C.J.; Wood, E.F.; Wood, H.; Wunsch, C.

    2007-01-01

    Climatic change is gaining ground and with no doubt is stimulated by human activities. It is therefore urgent to better understand its nature, importance and potential impacts. The chapters of this book have been written by US and French experts of the global warming question. After a description of the Intergovernmental Panel on Climate Change (IPCC, GIEC in French) consensus, they present the past and present researches on each of the main component of the climate system, on the question of climatic change impacts and on the possible answers. The conclusion summarizes the results of each chapter. Content: presentation of the IPCC; greenhouse effect, radiation balance and clouds; atmospheric aerosols and climatic change; global water cycle and climate; influence of climatic change on the continental hydrologic cycle; ocean and climate; ice and climate; global carbon cycle; about some impacts of climatic change on Europe and the Atlantic Ocean; interaction between atmospheric chemistry and climate; climate and society, the human dimension. (J.S.)

  4. Understanding person perception.

    Science.gov (United States)

    Young, Andrew W; Bruce, Vicki

    2011-11-01

    Bruce and Young's (1986) theoretical framework was actually a synthesis of ideas contributed by several people. Some of its insights have stood the test of time - especially the importance of using converging evidence from as wide a range of methods of enquiry as possible, and an emphasis on understanding the demands that are made by particular face perception tasks. But there were also areas where Bruce and Young failed to obey their own edicts (emotion recognition), and some topics they simply omitted (gaze perception). We discuss these, and then look at how the field has been transformed by computing developments, finishing with a few thoughts about where things may go over the next few (25?) years. ©2011 The British Psychological Society.

  5. Understanding Defense Mechanisms.

    Science.gov (United States)

    Cramer, Phebe

    2015-12-01

    Understanding defense mechanisms is an important part of psychotherapy. In this article, we trace the history of the concept of defense, from its origin with Freud to current views. The issue of defense as an unconscious mechanism is examined. The question of whether defenses are pathological, as well as their relation to pathology, is discussed. The effect of psychotherapy on the use of defenses, and their relation to a therapeutic alliance is explored. A series of empirical research studies that demonstrate the functioning of defense mechanisms and that support the theory is presented. Research also shows that as part of normal development, different defenses emerge at different developmental periods, and that gender differences in defense use occur.

  6. Understanding social motor coordination.

    Science.gov (United States)

    Schmidt, R C; Fitzpatrick, Paula; Caron, Robert; Mergeche, Joanna

    2011-10-01

    Recently there has been much interest in social coordination of motor movements, or as it is referred to by some researchers, joint action. This paper reviews the cognitive perspective's common coding/mirror neuron theory of joint action, describes some of its limitations and then presents the behavioral dynamics perspective as an alternative way of understanding social motor coordination. In particular, behavioral dynamics' ability to explain the temporal coordination of interacting individuals is detailed. Two experiments are then described that demonstrate how dynamical processes of synchronization are apparent in the coordination underlying everyday joint actions such as martial art exercises, hand-clapping games, and conversations. The import of this evidence is that emergent dynamic patterns such as synchronization are the behavioral order that any neural substrate supporting joint action (e.g., mirror systems) would have to sustain. Copyright © 2010 Elsevier B.V. All rights reserved.

  7. Understanding traditional African healing.

    Science.gov (United States)

    Mokgobi, M G

    2014-09-01

    Traditional African healing has been in existence for many centuries yet many people still seem not to understand how it relates to God and religion/spirituality. Some people seem to believe that traditional healers worship the ancestors and not God. It is therefore the aim of this paper to clarify this relationship by discussing a chain of communication between the worshipers and the Almighty God. Other aspects of traditional healing namely types of traditional healers, training of traditional healers as well as the role of traditional healers in their communities are discussed. In conclusion, the services of traditional healers go far beyond the uses of herbs for physical illnesses. Traditional healers serve many roles which include but not limited to custodians of the traditional African religion and customs, educators about culture, counselors, social workers and psychologists.

  8. Exploring Opponent Formats

    DEFF Research Database (Denmark)

    Jensen, Mads Møller; Rasmussen, Majken; Grønbæk, Kaj

    2013-01-01

    of how the opponent format and relationships impact a game are almost absent in current research. Thus, this paper aims to elucidate how the perception of a competition differs, depending on the opponent format, by presenting a game mechanic framework. The paper furthermore presents an interactive...... football-training platform, as well as games designed to explore the different opponent formats. The games are qualitatively evaluated to illuminate the qualities of and distinctions between different types of opponent formats, proposed by the framework terminology....

  9. ENDF/B format

    International Nuclear Information System (INIS)

    Khalil, M.A.; Lemmel, H.D.

    1986-09-01

    This document is a brief user's description of the format of ENDF/B. This format, originally designed for the US Evaluated Nuclear Data File, is recommended for international use. This summary is an aid to customers of the IAEA Nuclear Data Section when receiving data retrievals in ENDF/B format. For more detailed information the report BNL-NCS-50496 (ENDF 102) should be consulted. An Appendix to the present document gives a summary of the format differences between ENDF/B-4 and ENDF/B-5. (author)

  10. Data format translation routines

    International Nuclear Information System (INIS)

    Burris, R.D.

    1981-02-01

    To enable the effective connection of several dissimilar computers into a network, modification of the data being passed from one computer to another may become necessary. This document describes a package of routines which permit the translation of data in PDP-8 formats to PDP-11 or DECsystem-10 formats or from PDP-11 format to DECsystem-10 format. Additional routines are described which permit the effective use of the translation routines in the environment of the Fusion Energy Division (FED) network and the Elmo Bumpy Torus (EBT) data base

  11. Tribofilms: aspects of formation, stability and removal

    Energy Technology Data Exchange (ETDEWEB)

    Morina, Ardian; Neville, Anne [Institute of Engineering Thermofluids, Surfaces and Interfaces, School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT (United Kingdom)

    2007-09-21

    There has been much attention paid to the lubricant additives zinc dialkyldithiphosphate and molybdenum dialkyldithiocarbamate as the most commonly used antiwear/antioxidant and friction modifiers. The mechanism by which they function has been the subject of much research work. As a result of these efforts the tribofilms formed from the above additives are fully chemically characterized but understanding the physical properties and the dynamics of their formation, stability and removal is still not satisfactory and needs more research. This paper reviews the general characteristics of tribofilms formed from these additives in single component systems and also on their interactions as well as the current understanding of the dynamics of their formation. Experimental work is then presented alongside discussion of the literature to present a current status of understanding of the stability and the removal of tribofilms. The effect of temperature and additive interactions on the thickness of the steady state tribofilms, and consequently the effect on friction performance, is evaluated. The results of this study show that temperature and additive interactions play a significant role on the dynamic process of tribofilm formation as well as its chemical properties. This study also highlights the areas in which further development is needed to ensure progress in understanding of the tribofilm's formation and removal processes.

  12. Mark formation modeling in optical rewritable recording

    NARCIS (Netherlands)

    Brusche, J.H.; Segal, A.; Vuik, C.; Urbach, H.P.

    2006-01-01

    In optical rewritable recording media, such as the Blu-ray Disc, amorphous marks are formed on a crystalline background of a phase-change layer, by means of short, high power laser pulses. In order to improve this data storage concept, it is of great importance to understand the mark formation

  13. Modes, Genres, and Formats, Oh My!

    Science.gov (United States)

    Culham, Ruth

    2016-01-01

    The precision of terminology and language used with students can be a help or a hindrance to teaching writing. This article explores the writing instruction terms mode, genre, and format, and establishes the need for a common language to understand and apply them consistently across teachers and grades.

  14. Epigenetic Regulation of Memory Formation and Maintenance

    Science.gov (United States)

    Zovkic, Iva B.; Guzman-Karlsson, Mikael C.; Sweatt, J. David

    2013-01-01

    Understanding the cellular and molecular mechanisms underlying the formation and maintenance of memories is a central goal of the neuroscience community. It is well regarded that an organism's ability to lastingly adapt its behavior in response to a transient environmental stimulus relies on the central nervous system's capability for structural…

  15. Linking the Scales of Star Formation

    Science.gov (United States)

    Calzetti, Daniela; and the LEGUS Team

    2018-01-01

    Understanding galaxy evolution requires understanding star formation and its dependence on the local environment, spanning the scales from individual stars to kpc–size structures. The physical conditions within galaxies determine the formation of stars, star clusters, and larger structures, and their subsequent evolution. Observations of external galaxies with the HST that include the UV have enabled the characterization of the young stellar populations with unprecedented accuracy and detail, thus aiding the census and description of those populations. We are now in a position to quantify the spatial distribution and clustering of young stars, and investigate the impact and imprint of the physical conditions of both the local and global environment on the formation and evolution of the multi-scale structures. This talk describes the Legacy ExtraGalactic UV Survey (LEGUS), an HST Treasury programs aimed at investigating these issues using multi-color imaging, from the near-UV to the I, of a sample of fifty nearby galaxies.

  16. Tools for Understanding Identity

    Energy Technology Data Exchange (ETDEWEB)

    Creese, Sadie; Gibson-Robinson, Thomas; Goldsmith, Michael; Hodges, Duncan; Kim, Dee DH; Love, Oriana J.; Nurse, Jason R.; Pike, William A.; Scholtz, Jean

    2013-12-28

    Identity attribution and enrichment is critical to many aspects of law-enforcement and intelligence gathering; this identity typically spans a number of domains in the natural-world such as biographic information (factual information – e.g. names, addresses), biometric information (e.g. fingerprints) and psychological information. In addition to these natural-world projections of identity, identity elements are projected in the cyber-world. Conversely, undesirable elements may use similar techniques to target individuals for spear-phishing attacks (or worse), and potential targets or their organizations may want to determine how to minimize the attack surface exposed. Our research has been exploring the construction of a mathematical model for identity that supports such holistic identities. The model captures the ways in which an identity is constructed through a combination of data elements (e.g. a username on a forum, an address, a telephone number). Some of these elements may allow new characteristics to be inferred, hence enriching the holistic view of the identity. An example use-case would be the inference of real names from usernames, the ‘path’ created by inferring new elements of identity is highlighted in the ‘critical information’ panel. Individual attribution exercises can be understood as paths through a number of elements. Intuitively the entire realizable ‘capability’ can be modeled as a directed graph, where the elements are nodes and the inferences are represented by links connecting one or more antecedents with a conclusion. The model can be operationalized with two levels of tool support described in this paper, the first is a working prototype, the second is expected to reach prototype by July 2013: Understanding the Model The tool allows a user to easily determine, given a particular set of inferences and attributes, which elements or inferences are of most value to an investigator (or an attacker). The tool is also able to take

  17. ENDF/B Format

    International Nuclear Information System (INIS)

    Khalil, M.A.

    1975-01-01

    This document is a brief user's description of the format of ENDF/B, the evaluated neutron nuclear data library of the US National Nuclear Data Center. This summary is an aid to customers of the IAEA Nuclear Data Section when receiving data retrievals in ENDF/B format. For more detailed information the report BNL-50274 (ENDF-102) should be consulted. (author)

  18. Diminutive formations in Xitsonga

    African Journals Online (AJOL)

    Kate H

    Introduction. In Xitsonga diminutive formation, the juncture between the root and the suffix undergoes various phonological processes: glide formation, velarisation and vowel deletion. We argue that these seemingly disjointed processes are results of repair strategies that apply in order to avoid a sequence of labial sounds.

  19. Divisions-ST Formation

    CERN Document Server

    Henny, L

    2001-01-01

    Au CERN la formation est une partie intégrante des activités de l'Organisation. Mentionnée dans le Statut du Personnel depuis l'origine, elle figure au Règlement depuis 1981 et est largement explicitée dans la Circulaire Administrative N° 16. L'organe réglementaire est constitué par la Commission Paritaire de Formation (Joint Training Board dont le sigle est JTB) qui a pour but de conseiller le Directeur Général en matière de formation, de définir la politique de formation et d'en faire l'évaluation. Des organes spécifiques ont été mis en place pour organiser les différents programmes : le Groupe Formation et Développement, le Comité exécutif de formation (sigle TEC), le Comité d'enseignement académique. Des délégués divisionnaires à la formation (sigle DTO) servent de courroie de transmission entre ces organes, le personnel et le Service de l'Enseignement (Div. HR). La Division ST dont les activités présentent une grande variété se doit de poursuivre une politique de formation s...

  20. Towards understanding oral health.

    Science.gov (United States)

    Zaura, Egija; ten Cate, Jacob M

    2015-01-01

    During the last century, dental research has focused on unraveling the mechanisms behind various oral pathologies, while oral health was typically described as the mere absence of oral diseases. The term 'oral microbial homeostasis' is used to describe the capacity of the oral ecosystem to maintain microbial community stability in health. However, the oral ecosystem itself is not stable: throughout life an individual undergoes multiple physiological changes while progressing through infancy, childhood, adolescence, adulthood and old age. Recent discussions on the definition of general health have led to the proposal that health is the ability of the individual to adapt to physiological changes, a condition known as allostasis. In this paper the allostasis principle is applied to the oral ecosystem. The multidimensionality of the host factors contributing to allostasis in the oral cavity is illustrated with an example on changes occurring in puberty. The complex phenomenon of oral health and the processes that prevent the ecosystem from collapsing during allostatic changes in the entire body are far from being understood. As yet individual components (e.g. hard tissues, microbiome, saliva, host response) have been investigated, while only by consolidating these and assessing their multidimensional interactions should we be able to obtain a comprehensive understanding of the ecosystem, which in turn could serve to develop rational schemes to maintain health. Adapting such a 'system approach' comes with major practical challenges for the entire research field and will require vast resources and large-scale multidisciplinary collaborations. 2015 S. Karger AG, Basel

  1. Understanding anatomical terms.

    Science.gov (United States)

    Mehta, L A; Natrajan, M; Kothari, M L

    1996-01-01

    Words are our masters and words are our slaves, all depending on how we use them. The whole of medical science owes its origin to Greco-Roman culture and is replete with terms whose high sound is not necessarily accompanied by sound meaning. This is even more the case in the initial, pre-clinical years. Anatomical terminology seems bewildering to the initiate; and maybe that is a reason why love of anatomy as a subject does not always spill over through later years. Employing certain classifications of the origin of the anatomical terms, we have prepared an anthology that we hope will ease the student's task and also heighten the student's appreciation of the new terms. This centers on revealing the Kiplingian "how, why, when, where, what, and who" of a given term. This presentation should empower students to independently formulate a wide network of correlations once they understand a particular term. The article thus hopes to stimulate students' analytic and synthetic faculties as well. A small effort can reap large rewards in terms of enjoyment of the study of anatomy and the related subjects of histology, embryology, and genetics. It is helpful to teachers and students alike. This exercise in semantics and etymology does not demand of the student or his teacher any background in linguistics, grammar, Greek, Latin, Sanskrit, anatomy, or medicine.

  2. Understanding the supply chain

    Directory of Open Access Journals (Sweden)

    Aćimović Slobodan

    2006-01-01

    Full Text Available Supply chain management represents new business philosophy and includes strategically positioned and much wider scope of activity in comparison with its "older brother" - management of logistics. Philosophy of the concept of supply chain is directed to more coordination of key business functions of every link in distribution chain in the process of organization of the flow of both goods and information, while logistic managing instruments are focused on internal optimum of flows of goods and information within one company. Applying the concept of integrated supply chain among several companies makes the importance of operative logistics activity even greater on the level of one company, thus advancing processes of optimum and coordination within and between different companies and confirms the importance of logistics performances for the company’s profitability. Besides the fact that the borders between companies are being deleted, this concept of supply chain in one distribution channel influences increasing of importance of functional, i.e. traditional business managing approaches but instead it points out the importance of process managing approaches. Although the author is aware that "there is nothing harder, more dangerous and with uncertain success, but to find a way for introducing some novelties (Machiavelli, it would be even his additional stimulation for trying to bring closer the concept and goals of supply chain implementation that are identified in key, relevant, modern, theoretical and consulting approaches in order to achieve better understanding of the subject and faster implementation of the concept of supply chain management by domestic companies.

  3. Understanding Autism in Schizophrenia

    Directory of Open Access Journals (Sweden)

    Arnaldo Ballerini

    2012-01-01

    Full Text Available Detachment from external reality, distancing from others, closure into a sort of virtual hermitage, and prevalence of inner fantasies, are the descriptive aspects of autism. However, from an anthropological-phenomenological point of view, in schizophrenia, the autistic mode of life can arise from a person’s being confronted with a pathological crisis in the obviousness of the intersubjective world, essentially a crisis in the intersubjective foundation of human presence. The “condition of possibility” of the autistic way of being is the deficiency of the operation that phenomenology call empathetic-intuitive constitution of the Other, an Other which is the naturalness of evidence of being a subject like me. The theme of the Other, of intersubjectivity, has become so central in the psychopathological analysis of schizophrenic disorders because the modifications of interhuman encounter cannot be seen as the secondary consequences of symptoms but constitute the fundamental disorder of schizophrenic alienation. Revision of the concept of autism from the original definition, centered on the prevalence of inner fantasies, leads to the profound change with the vision of autism as “loss” and “void.” I call attention to possibility of phenomenological research to understand autistic world starting from this “void.”

  4. Understanding autism in schizophrenia.

    Science.gov (United States)

    Ballerini, Arnaldo

    2012-01-01

    Detachment from external reality, distancing from others, closure into a sort of virtual hermitage, and prevalence of inner fantasies, are the descriptive aspects of autism. However, from an anthropological-phenomenological point of view, in schizophrenia, the autistic mode of life can arise from a person's being confronted with a pathological crisis in the obviousness of the intersubjective world, essentially a crisis in the intersubjective foundation of human presence. The "condition of possibility" of the autistic way of being is the deficiency of the operation that phenomenology call empathetic-intuitive constitution of the Other, an Other which is the naturalness of evidence of being a subject like me. The theme of the Other, of intersubjectivity, has become so central in the psychopathological analysis of schizophrenic disorders because the modifications of interhuman encounter cannot be seen as the secondary consequences of symptoms but constitute the fundamental disorder of schizophrenic alienation. Revision of the concept of autism from the original definition, centered on the prevalence of inner fantasies, leads to the profound change with the vision of autism as "loss" and "void." I call attention to possibility of phenomenological research to understand autistic world starting from this "void."

  5. Volume Hologram Formation in SU-8 Photoresist

    Directory of Open Access Journals (Sweden)

    Tina Sabel

    2017-05-01

    Full Text Available In order to further understand the mechanism of volume hologram formation in photosensitive polymers, light-induced material response is analyzed in commonly used epoxy-based negative photoresist Epon SU-8. For this purpose, time-resolved investigation of volume holographic grating growth is performed in the SU-8 based host–guest system and in the pure SU-8 material, respectively. The comparison of grating growth curves from doped and undoped system allows us to draw conclusions on the impact of individual components on the grating formation process. The successive formation of transient absorption as well as phase gratings in SU-8 is observed. Influence of exposure duration and UV flood cure on the grating growth are investigated. Observed volume holographic grating formation in SU-8 can be explained based on the generation and subsequent diffusion of photoacid as well as time-delayed polymerization of exposed and unexposed areas.

  6. Formation of soap bubbles by gas jet

    Science.gov (United States)

    Zhou, Maolei; Li, Min; Chen, Zhiyuan; Han, Jifeng; Liu, Dong

    2017-12-01

    Soap bubbles can be easily generated by various methods, while their formation process is complicated and still worth studying. A model about the bubble formation process was proposed in the study by Salkin et al. [Phys. Rev. Lett. 116, 077801 (2016)] recently, and it was reported that the bubbles were formed when the gas blowing velocity was above one threshold. However, after a detailed study of these experiments, we found that the bubbles could be generated in two velocity ranges which corresponded to the laminar and turbulent gas jet, respectively, and the predicted threshold was only effective for turbulent gas flow. The study revealed that the bubble formation was greatly influenced by the aerodynamics of the gas jet blowing to the film, and these results will help to further understand the formation mechanism of the soap bubble as well as the interaction between the gas jet and the thin liquid film.

  7. Right timing in formative program evaluation.

    Science.gov (United States)

    Hall, Jori; Freeman, Melissa; Roulston, Kathy

    2014-08-01

    Since many educational researchers and program developers have limited knowledge of formative evaluation, formative data may be underutilized during the development and implementation of an educational program. The purpose of this article is to explain how participatory, responsive, educative, and qualitative approaches to formative evaluation can facilitate a partnership between evaluators and educational researchers and program managers to generate data useful to inform program implementation and improvement. This partnership is critical, we argue, because it enables an awareness of when to take appropriate action to ensure successful educational programs or "kairos". To illustrate, we use examples from our own evaluation work to highlight how formative evaluation may facilitate opportune moments to (1) define the substance and purpose of a program, (2) develop understanding and awareness of the cultural interpretations of program participants, and (3) show the relevance of stakeholder experiences to program goals. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Understanding Social Media Logic

    Directory of Open Access Journals (Sweden)

    José van Dijck

    2013-08-01

    Full Text Available Over the past decade, social media platforms have penetrated deeply into the mech­anics of everyday life, affecting people's informal interactions, as well as institutional structures and professional routines. Far from being neutral platforms for everyone, social media have changed the conditions and rules of social interaction. In this article, we examine the intricate dynamic between social media platforms, mass media, users, and social institutions by calling attention to social media logic—the norms, strategies, mechanisms, and economies—underpin­ning its dynamics. This logic will be considered in light of what has been identified as mass me­dia logic, which has helped spread the media's powerful discourse outside its institutional boundaries. Theorizing social media logic, we identify four grounding principles—programmabil­ity, popularity, connectivity, and datafication—and argue that these principles become increas­ingly entangled with mass media logic. The logic of social media, rooted in these grounding principles and strategies, is gradually invading all areas of public life. Besides print news and broadcasting, it also affects law and order, social activism, politics, and so forth. Therefore, its sustaining logic and widespread dissemination deserve to be scrutinized in detail in order to better understand its impact in various domains. Concentrating on the tactics and strategies at work in social media logic, we reassess the constellation of power relationships in which social practices unfold, raising questions such as: How does social media logic modify or enhance ex­isting mass media logic? And how is this new media logic exported beyond the boundaries of (social or mass media proper? The underlying principles, tactics, and strategies may be relat­ively simple to identify, but it is much harder to map the complex connections between plat­forms that distribute this logic: users that employ them, technologies that

  9. Understanding individual routing behaviour.

    Science.gov (United States)

    Lima, Antonio; Stanojevic, Rade; Papagiannaki, Dina; Rodriguez, Pablo; González, Marta C

    2016-03-01

    Knowing how individuals move between places is fundamental to advance our understanding of human mobility (González et al. 2008 Nature 453, 779-782. (doi:10.1038/nature06958)), improve our urban infrastructure (Prato 2009 J. Choice Model. 2, 65-100. (doi:10.1016/S1755-5345(13)70005-8)) and drive the development of transportation systems. Current route-choice models that are used in transportation planning are based on the widely accepted assumption that people follow the minimum cost path (Wardrop 1952 Proc. Inst. Civ. Eng. 1, 325-362. (doi:10.1680/ipeds.1952.11362)), despite little empirical support. Fine-grained location traces collected by smart devices give us today an unprecedented opportunity to learn how citizens organize their travel plans into a set of routes, and how similar behaviour patterns emerge among distinct individual choices. Here we study 92 419 anonymized GPS trajectories describing the movement of personal cars over an 18-month period. We group user trips by origin-destination and we find that most drivers use a small number of routes for their routine journeys, and tend to have a preferred route for frequent trips. In contrast to the cost minimization assumption, we also find that a significant fraction of drivers' routes are not optimal. We present a spatial probability distribution that bounds the route selection space within an ellipse, having the origin and the destination as focal points, characterized by high eccentricity independent of the scale. While individual routing choices are not captured by path optimization, their spatial bounds are similar, even for trips performed by distinct individuals and at various scales. These basic discoveries can inform realistic route-choice models that are not based on optimization, having an impact on several applications, such as infrastructure planning, routing recommendation systems and new mobility solutions. © 2016 The Author(s).

  10. Geoparks for understanding geodiversity

    Science.gov (United States)

    Anttila-Muilu, Sirpa

    2015-04-01

    used to enhance the understanding of geodiversity - through different scales.

  11. Understanding "people" people.

    Science.gov (United States)

    Butler, Timothy; Waldroop, James

    2004-06-01

    Nearly all areas of business--not just sales and human resources--call for interpersonal savvy. Relational know-how comprises a greater variety of aptitudes than many executives think. Some people can "talk a dog off a meat truck," as the saying goes. Others are great at resolving interpersonal conflicts. Some have a knack for translating high-level concepts for the masses. And others thrive when they're managing a team. Since people do their best work when it most closely matches their interests, the authors contend, managers can increase productivity by taking into account employees' relational interests and skills when making personnel choices and project assignments. After analyzing psychological tests of more than 7,000 business professionals, the authors have identified four dimensions of relational work: influence, interpersonal facilitation, relational creativity, and team leadership. This article explains each one and offers practical advice to managers--how to build a well-balanced team, for instance, and how to gauge the relational skills of potential employees during interviews. To determine whether a job candidate excels in, say, relational creativity, ask her to describe her favorite advertising campaign, slogan, or image and tell you why she finds it to be so effective. Understanding these four dimensions will help you get optimal performance from your employees, appropriately reward their work, and assist them in setting career goals. It will also help you make better choices when it comes to your own career development. To get started, try the authors' free online assessment tool, which will measure both your orientation toward relational work in general and your interest level in each of its four dimensions.

  12. Manuel UNIMARC format bibliographique

    CERN Document Server

    2007-01-01

    This manual is the French translation of the second edition of UNIMARC Manual: bibliographic format published in English in 1994 and completed by 5 updates published from 1996 to 2005. This 5th French edition is composite. It reproduces identically a part of the 4th edition published in 2002 and, for the fields of the format modified in the Update 5, it offers a new more structured presentation. This is a handbook dedicated to French-speaking users of the UNIMARC format for bibliographic descriptions.

  13. Fragmentation during primordial star formation

    Science.gov (United States)

    Dutta, Jayanta

    Understanding the physics of the very first stars in the universe, the so-called Population III (or Pop III) stars, is crucial in determining how the universe evolved into what we observe today. In the standard model of Pop III star formation, the baryonic matter, mainly atomic hydrogen, collapses gravitationally into small Dark Matter (DM) minihalos. However, so far there is little understanding on how the thermal, dynamical and chemical evolution of the primordial gas depend on the initial configuration of the minihalos (for example, rotation of the unstable clumps inside minihalos, turbulence, formation of molecular hydrogen and cosmic variance of the minihalos). We use the modified version of the Gadget-2 code, a three-dimensional smoothed particle hydrodynamics (SPH) simulations, to follow the evolution of the collapsing gas in both idealized as well as more realistic minihalos. Unlike some earlier cosmological calculations, the implementation of sink particles allows us to follow the evolution of the accretion disk that builds up in the centre of each minihalo and fragments. We find that the fragmentation behavior depends on the adopted choice of three-body H2 formation rate coefficient. The increasing cooling rate during rapid conversion of the atomic to molecular hydrogen is offset by the heating due to gas contraction. We propose that the H2 cooling, the heating due to H2 formation and compressional heating together set a density and temperature structure in the disk that favors fragmentation. We also find that the cloud's initial degree of rotation has a significant effect on the thermal and dynamical evolution of the collapsing gas. Clouds with higher rotation exhibit spiral-arm-like structures that become gravitationally unstable to fragmentation on several scales. These type of clouds tend to fragment more and have lower accretion rates compared to their slowly rotating counterparts. In addition, we find that the distribution of specific angular

  14. Understanding Nitrogen Fixation

    Energy Technology Data Exchange (ETDEWEB)

    Paul J. Chirik

    2012-05-25

    The purpose of our program is to explore fundamental chemistry relevant to the discovery of energy efficient methods for the conversion of atmospheric nitrogen (N{sub 2}) into more value-added nitrogen-containing organic molecules. Such transformations are key for domestic energy security and the reduction of fossil fuel dependencies. With DOE support, we have synthesized families of zirconium and hafnium dinitrogen complexes with elongated and activated N-N bonds that exhibit rich N{sub 2} functionalization chemistry. Having elucidated new methods for N-H bond formation from dihydrogen, C-H bonds and Broensted acids, we have since turned our attention to N-C bond construction. These reactions are particularly important for the synthesis of amines, heterocycles and hydrazines with a range of applications in the fine and commodity chemicals industries and as fuels. One recent highlight was the discovery of a new N{sub 2} cleavage reaction upon addition of carbon monoxide which resulted in the synthesis of an important fertilizer, oxamide, from the diatomics with the two strongest bonds in chemistry. Nitrogen-carbon bonds form the backbone of many important organic molecules, especially those used in the fertilizer and pharamaceutical industries. During the past year, we have continued our work in the synthesis of hydrazines of various substitution patterns, many of which are important precursors for heterocycles. In most instances, the direct functionalization of N{sub 2} offers a more efficient synthetic route than traditional organic methods. In addition, we have also discovered a unique CO-induced N{sub 2} bond cleavage reaction that simultaneously cleaves the N-N bond of the metal dinitrogen compound and assembles new C-C bond and two new N-C bonds. Treatment of the CO-functionalized core with weak Broensted acids liberated oxamide, H{sub 2}NC(O)C(O)NH{sub 2}, an important slow release fertilizer that is of interest to replace urea in many applications. The

  15. Capital formation in new cooperatives in China: policy and practice

    OpenAIRE

    Li Zhao

    2011-01-01

    This paper aims to fill one knowledge gap on understanding the issue of capital formation in new co-operatives in developing countries. By doing so, it presents the main findings of capital formation and investment in a small sample of horticulture shareholding co-operatives in rural China, because shareholding co-operatives, as one best example of new multi-stakeholder co-operatives in China, have become a vehicle to mobilize additional resources. To better understand shareholder co-operativ...

  16. Cosmology and galaxy formation

    International Nuclear Information System (INIS)

    Rees, M.J.

    1977-01-01

    Implications of the massive halos and ''missing mass'' for galaxy formation are addressed; it is suggested that this mass consists of ''Population III'' stars that formed before the galaxies did. 19 references

  17. PCF File Format.

    Energy Technology Data Exchange (ETDEWEB)

    Thoreson, Gregory G [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-08-01

    PCF files are binary files designed to contain gamma spectra and neutron count rates from radiation sensors. It is the native format for the GAmma Detector Response and Analysis Software (GADRAS) package [1]. It can contain multiple spectra and information about each spectrum such as energy calibration. This document outlines the format of the file that would allow one to write a computer program to parse and write such files.

  18. Influence of Streptococcus mutans on Enterococcus faecalis Biofilm Formation

    NARCIS (Netherlands)

    Deng, Dong Mei; Hoogenkamp, Michel A.; Exterkate, Rob A. M.; Jiang, Lei Meng; van der Sluis, Lucas W. M.; ten Cate, Jacob M.; Crielaard, Wim

    Introduction: An important virulence factor of Enterococcus faecalis is its ability to form biofilms. Most studies on biofilm formation have been carried out by using E. faecalis monocultures. Given the polymicrobial nature of root canal infections, it is important to understand biofilm formation of

  19. Utilizing dendritic scaffold for feasible formation of naphthalene ...

    Indian Academy of Sciences (India)

    the effect of dendritic scaffolds on the feasibility of naphthalene excimer formation has not been reported in the literature. Here, we report synthesis and photophysical study of naphthalene functionalized zero and first genera- tion PAMAM dendrimers in order to understand the mechanism of excimer formation in the system.

  20. Gott time machines, BTZ black hole formation, and choptuik scaling

    Science.gov (United States)

    Birmingham; Sen

    2000-02-07

    We study the formation of Banados-Teitelboim-Zanelli black holes by the collision of point particles. It is shown that the Gott time machine, originally constructed for the case of vanishing cosmological constant, provides a precise mechanism for black hole formation. As a result, one obtains an exact analytic understanding of the Choptuik scaling.

  1. Circuit Formation by Spatio-Temporal Control of Messenger RNA ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Circuit Formation by Spatio-Temporal Control of Messenger RNA Translation. The connections inside the brain need to be wired in a precise manner during development to ensure its proper function. This project will provide insight into circuit formation to help us understand how axon regeneration can improve clinical ...

  2. Influence of Streptococcus mutans on enterococcus faecalis biofilm formation

    NARCIS (Netherlands)

    Deng, D.M.; Hoogenkamp, M.A.; Exterkate, R.A.M.; Jiang, L.M.; van der Sluis, L.W.M.; ten Cate, J.M.; Crielaard, W.

    2009-01-01

    Introduction: An important virulence factor of Enterococcus faecalis is its ability to form biofilms. Most studies on biofilm formation have been carried out by using E. faecalis monocultures. Given the polymicrobial nature of root canal infections, it is important to understand biofilm formation of

  3. Formative Assessment: Improvement, Immediacy and the Edge for Learning

    Science.gov (United States)

    Staunton, Mike; Dann, Chris

    2016-01-01

    Formative assessment is about strengthening student learning and can dramatically improve student achievement when it guides changes in day-to-day classroom practice. Any attempt to understand formative assessment must therefore be grounded in a notion of learning, which this paper approaches from a constructivist/experiential perspective.…

  4. Interstellar Medium and Star Formation Studies with the Square ...

    Indian Academy of Sciences (India)

    studies, augmented by theoretical and laboratory studies in the last three decades or so have been successful in providing a framework to understand the formation of stars and ..... mass stars which are observationally a reality. The current theoretical and observational status of high mass star formation has been recently ...

  5. Formation of Irreversible H-bonds in Cellulose Materials

    Science.gov (United States)

    Umesh P. Agarwal; Sally A. Ralph; Rick S. Reiner; Nicole M. Stark

    2015-01-01

    Understanding of formation of irreversible Hbonds in cellulose is important in a number of fields. For example, fields as diverse as pulp and paper and enzymatic saccharification of cellulose are affected. In the present investigation, the phenomenon of formation of irreversible H-bonds is studied in a variety of celluloses and under two different drying conditions....

  6. Formation and evolution of yardangs activated by Late Pleistocene ...

    Indian Academy of Sciences (India)

    mainly by wind erosion in the following evolution, with relatively short stationary phases. This research focused on the determination of endogenic processes of yardangs formation, which would contribute to further understanding of yardangs formation from a geological perspective and promote further study of yardang ...

  7. Real-Time Monitoring of Nanoparticle Formation by FRET Imaging

    NARCIS (Netherlands)

    Sanchez-Gaytan, Brenda L.; Fay, Francois; Hak, Sjoerd; Alaarg, Amr Muhmed Sabry Abdelhakeem; Fayad, Zahi A.; Perez-Medina, Carlos; Mulder, Willem J.M.; Zhao, Yiming

    2017-01-01

    Understanding the formation process of nanoparticles is of the utmost importance to improve their design and production. This especially holds true for self-assembled nanoparticles whose formation processes have been largely overlooked. Herein, we present a new technology that integrates a

  8. Autonomous Formation Flight

    Science.gov (United States)

    Schkolnik, Gerard S.; Cobleigh, Brent

    2004-01-01

    NASA's Strategic Plan for the Aerospace Technology Enterprise includes ambitious objectives focused on affordable air travel, reduced emissions, and expanded aviation-system capacity. NASA Dryden Flight Research Center, in cooperation with NASA Ames Research Center, the Boeing Company, and the University of California, Los Angeles, has embarked on an autonomous-formation-flight project that promises to make significant strides towards these goals. For millions of years, birds have taken advantage of the aerodynamic benefit of flying in formation. The traditional "V" formation flown by many species of birds (including gulls, pelicans, and geese) enables each of the trailing birds to fly in the upwash flow field that exists just outboard of the bird immediately ahead in the formation. The result for each trailing bird is a decrease in induced drag and thus a reduction in the energy needed to maintain a given speed. Hence, for migratory birds, formation flight extends the range of the system of birds over the range of birds flying solo. The Autonomous Formation Flight (AFF) Project is seeking to extend this symbiotic relationship to aircraft.

  9. Understanding Metaphorical Use of Verbs

    National Research Council Canada - National Science Library

    Torreano, Lisa

    1997-01-01

    How do people understand language in which verbs are used metaphorically? For example, how do people understand utterances such as He bathed in her beauty or She punctured his ego in everyday conversation...

  10. Planetesimal formation starts at the snow line

    Science.gov (United States)

    Drążkowska, J.; Alibert, Y.

    2017-12-01

    Context. The formation stage of planetesimals represents a major gap in our understanding of the planet formation process. Late-stage planet accretion models typically make arbitrary assumptions about planetesimal and pebble distribution, while dust evolution models predict that planetesimal formation is only possible at some orbital distances. Aims: We wish to test the importance of the water snow line in triggering the formation of the first planetesimals during the gas-rich phase of a protoplanetary disk, when cores of giant planets have to form. Methods: We connected prescriptions for gas disk evolution, dust growth and fragmentation, water ice evaporation and recondensation, the transport of both solids and water vapor, and planetesimal formation via streaming instability into a single one-dimensional model for protoplanetary disk evolution. Results: We find that processes taking place around the snow line facilitate planetesimal formation in two ways. First, because the sticking properties between wet and dry aggregates change, a "traffic jam" inside of the snow line slows the fall of solids onto the star. Second, ice evaporation and outward diffusion of water followed by its recondensation increases the abundance of icy pebbles that trigger planetesimal formation via streaming instability just outside of the snow line. Conclusions: Planetesimal formation is hindered by growth barriers and radial drift and thus requires particular conditions to take place. The snow line is a favorable location where planetesimal formation is possible for a wide range of conditions, but not in every protoplanetary disk model, however. This process is particularly promoted in large cool disks with low intrinsic turbulence and an increased initial dust-to-gas ratio. The movie attached to Fig. 3 is only available at http://www.aanda.org

  11. The forensics of fulgurite formation

    Science.gov (United States)

    Pasek, Matthew A.; Pasek, Virginia D.

    2018-04-01

    Natural disasters such as forest fires can result in extensive and costly property damage. These events may be the result of a human error or system failure triggered by electrical discharge, and in such circumstances may form a fulgurite. Understanding fulgurites and their formation may be critical in determining the cause of the fire or other, shock-related event. Here we identify several distinguishing features of fulgurites formed in association with downed power lines, including the presence of melted conductors, transformation of quartz to cristobalite, and morphological differences including increased glass percentage and smaller internal voids. These features are consequences of how heat is transferred to and through a target rock material as it melts and forms a fulgurite, and are predicted from both first principles of diffusive heat transfer, and empirically-derived reaction kinetics for mineral transformations.

  12. Densities and Kinematic Viscosities for the Systems Benzene + Methyl Formate, Benzene + Ethyl Formate, Benzene + Propyl Formate, and Benzene + Butyl Formate

    DEFF Research Database (Denmark)

    Emmerling, Uwe; Rasmussen, Peter

    1998-01-01

    Densities and kinematic viscosities have been measured for the system benzene + methyl formate at 20°C and for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate from 20°C to 50°C. The results for the system benzene + methyl formate have been correlated usi...

  13. Cavitation Effect of Shock Pressure about Nuclear Power Plant Component Cleaning or Crud Removal

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong Man; Lee, Seung Won; Park, Sung Dae; Kang, Sarah; Bang, In Cheol [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2011-05-15

    In nuclear power plant, the problems are caused by corrosion phenomena on the pipe or fuel elements. It can cause the additional cost for plant component recycling or disassembly. Those solutions of problem are chemical method and physical method. Recently ultrasonic and laser methods for cleaning are developing. If fluid flow is attached to the high speed surface of a blade, a large number of bubbles are developed. As it reaches vapor pressure, the fluid vaporizes and forms small bubbles of gas. This is cavitation. Previous study of cavitation shows that predict the onset of cavitation within the pump blade and the degradation in the pressure rise due to the generation and transport of vapor. But cavitation erosion effect can be used for optimized corrosion cleaning. Cavitation can be created in restrict region such as static mixer and orifice. When the bubbles collapse later, they typically cause very strong local shock waves in the fluid, which may be audible and may even damage the blades. Purpose of this study is using shock pressure by micro bubble collapse for second time cleaning in the fluid region of the on product surface

  14. Bone formation in axial spondyloarthritis.

    Science.gov (United States)

    Lories, Rik J; Haroon, Nigil

    2014-10-01

    The success of targeted therapies directed against tumor necrosis factor for patients with spondyloarthritis has shifted the focus of physicians and scientists towards the prevention of structural damage to the involved structures, in particular the sacroiliac joints and the spine, to avoid loss of function and disability. Structural damage to the skeleton as witnessed by radiography mainly consists of new bone formation potentially progressively leading to spine or joint ankylosis. This important long-term outcome parameter has been difficult to study, not alone because the time window for change may be long but also because human tissues with direct translational relevance are rarely available. Data from rodent models have identified growth factor signaling pathways as relevant targets. Both human and animal studies have tried to understand the link between inflammation and new bone formation. At the current moment, most evidence points towards a strong link between both but with the question still lingering about the sequence of events, disease triggers, and the interdependence of both features of disease. New discoveries such as a masterswitch T cell population that carries the IL23 receptor and the analysis of auto-antibodies directed again noggin and sclerostin are contributing to innovative insights into the pathophysiology of disease. Long-term data with tumor necrosis factor (TNF) inhibitors also suggest that some window of opportunity may exist to inhibit structural disease progression. All these data provide support for a further critical analysis of the available datasets and boost research in the field. The introduction of novel disease definitions, in particular the characterization of non-radiographic axial spondyloarthritis patients, will likely be instrumental in our further understanding of structural damage. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. A Faculty Toolkit for Formative Assessment in Pharmacy Education.

    Science.gov (United States)

    DiVall, Margarita V; Alston, Greg L; Bird, Eleanora; Buring, Shauna M; Kelley, Katherine A; Murphy, Nanci L; Schlesselman, Lauren S; Stowe, Cindy D; Szilagyi, Julianna E

    2014-11-15

    This paper aims to increase understanding and appreciation of formative assessment and its role in improving student outcomes and the instructional process, while educating faculty on formative techniques readily adaptable to various educational settings. Included are a definition of formative assessment and the distinction between formative and summative assessment. Various formative assessment strategies to evaluate student learning in classroom, laboratory, experiential, and interprofessional education settings are discussed. The role of reflective writing and portfolios, as well as the role of technology in formative assessment, are described. The paper also offers advice for formative assessment of faculty teaching. In conclusion, the authors emphasize the importance of creating a culture of assessment that embraces the concept of 360-degree assessment in both the development of a student's ability to demonstrate achievement of educational outcomes and a faculty member's ability to become an effective educator.

  16. Object formation and subject formation: The innovation campus in the Netherlands

    NARCIS (Netherlands)

    Kooij, H.J.

    2015-01-01

    A central question within planning theory is how changes between the relations of ‘grand institutions’ such as state, market and education influence the formation of objects ‘on the ground’. Drawing upon Foucault’s work, this article contributes to the understanding of these relations and argues

  17. Towards predictive simulations of soot formation: from surrogate to turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Blanquart, Guillaume [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    2017-03-28

    The combustion of transportation fuels leads to the formation of several kinds of pollutants, among which are soot particles. These particles, also formed during coal combustion and in fires, are the source of several health problems and environmental issues. Unfortunately, our current understanding of the chemical and physical phenomena leading to the formation of soot particles remains incomplete, and as a result, the predictive capability of our numerical tools is lacking. The objective of the work was to reduce the gap in the present understanding and modeling of soot formation both in laminar and turbulent flames. The effort spanned several length scales from the molecular level to large scale turbulent transport.

  18. Formation of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Silberg, P.A. (2833 Lawton Drive, Amarillo, Texas (USA))

    A plasma continuum model for the formation of ball lightning is developed based on a substantial number of reports that the ball is often in the discharge column of a previous lightning stroke. The usual method of setting up the plasma equation for a one-component electron plasma is used. An approximate equation for the plasma is derived from the describing equation which is then solved exactly in terms of the Jacobi elliptic functions. The formation of the ball is based on a nonlinearity of the plasma equation which under certain circumstances permits the field to collapse into a small region. This collapse is interpreted to be ball lightning. The approximate equation derived for the plasma has the same form as a previous equation used to describe the formation of the fireball plasma.

  19. Tritiated ammonia formation

    International Nuclear Information System (INIS)

    Heung, L.K.

    1995-01-01

    When nitrogen was selected as the glovebox atmosphere for the Replacement Tritium Facility (RTF) at the Savannah River Site (SRS), a concern was raised as to the possibility of tritiated ammonia formation in the gloveboxes. Experimental data were produced to study the tritiated ammonia formation rate in a tritium and nitrogen mixture. A rate equation that closely simulates the experimental data was developed. This rate equation can be used to calculate the formation of tritiated ammonia from different concentrations of tritium and nitrogen. The reaction of T 2 and N 2 to form NT 3 is a slow process, particularly when the tritium concentration is low. The reaction requires weeks or months to reach radiochemical equilibrium dependent on the concentrations of the reactants. 4 refs., 6 figs., 1 tab

  20. Double layer formation

    International Nuclear Information System (INIS)

    Singh, N.

    1982-01-01

    Results from several numerical simulations of the formation of double layers in plasmas with a constant potential drop across them are presented. Here the emphasis is mainly on plasma processes during the formation of double layers. The recurring formation of double layers, their propagation and associated current interruptions are observed when the electron current injected into the simulation region from the low potential side exceeds the electron thermal current. This recurring process is stopped (or delayed) when the electron current recuperation is inhibited by a small magnetic force on the electrons. The motion of double layers is examined and it is found that the motion is caused by the interruption of the ion current from the high potential side. The subsequent recovery of this current renders the double layer stationary. (author)

  1. Densities and Kinematic Viscosities for the Systems Benzene + Methyl Formate, Benzene + Ethyl Formate, Benzene + Propyl Formate, and Benzene + Butyl Formate

    DEFF Research Database (Denmark)

    Emmerling, Uwe; Rasmussen, Peter

    1998-01-01

    Densities and kinematic viscosities have been measured for the system benzene + methyl formate at 20°C and for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate from 20°C to 50°C. The results for the system benzene + methyl formate have been correlated using...... a Redlich-Kister type of expression with temperature-independent parameters and the data for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate with temperature-dependent parameters. The viscosities have furthermore been compared to values predicted by means of the GC...

  2. The formation of stars

    CERN Document Server

    Stahler, Steven W

    2008-01-01

    This book is a comprehensive treatment of star formation, one of the most active fields of modern astronomy. The reader is guided through the subject in a logically compelling manner. Starting from a general description of stars and interstellar clouds, the authors delineate the earliest phases of stellar evolution. They discuss formation activity not only in the Milky Way, but also in other galaxies, both now and in the remote past. Theory and observation are thoroughly integrated, with the aid of numerous figures and images. In summary, this volume is an invaluable resource, both as a text f

  3. Situated Formative Feedback

    DEFF Research Database (Denmark)

    Lukassen, Niels Bech; Wahl, Christian; Sorensen, Elsebeth Korsgaard

    This study addresses the conceptual challenge of providing students with good quality feedback to enhance student learning in an online community of practice (COP). The aim of the study is to identify feedback mechanisms in a virtual learning environment (VLE) and to create a full formative...... refer to this type of feedback as, Situated Formative Feedback (SFF). As a basis for exploring, identifying and discussing relevant aspects of SFF the paper analyses qualitative data from a Moodle dialogue. Data are embedded in the qualitative analytic program Nvivo and are analysed with a system...

  4. Tea aroma formation

    Directory of Open Access Journals (Sweden)

    Chi-Tang Ho

    2015-03-01

    Full Text Available Besides water, tea is one of the most popular beverages around the world. The chemical ingredients and biological activities of tea have been summarized recently. The current review summarizes tea aroma compounds and their formation in green, black, and oolong tea. The flavor of tea can be divided into two categories: taste (non-volatile compounds and aroma (volatile compounds. All of these aroma molecules are generated from carotenoids, lipids, glycosides, etc. precursors, and also from Maillard reaction. In the current review, we focus on the formation mechanism of main aromas during the tea manufacturing process.

  5. Formation and Activation of Thermogenic Fat

    Science.gov (United States)

    Wu, Jun; Jun, Heejin; McDermott, Joseph R.

    2015-01-01

    Thermogenic fat cells that convert chemical energy into heat are present in both mice and humans. Recent years have witnessed a great advancement in our understanding of the regulation of these adipocytes and an increased appreciation of the potential these cells have to counteract obesity. Here we summarize recent efforts to understand the formation of these fat cells and critically review genetic models and other experimental tools currently available to further investigate the development and activation of both classical brown and inducible beige fat cells. We also discuss recent discoveries about the epigenetic regulation of these adipocytes, and finally present emerging evidence revealing the metabolic impacts of thermogenic fat in humans. PMID:25851693

  6. Understanding Gay and Lesbian Youth: Sticks, Stones, and Silence.

    Science.gov (United States)

    Vare, Jonatha W.; Norton, Terry L.

    1998-01-01

    Argues that young adult literature offers an appropriate means of developing an understanding of gay and lesbian youths, both for educators and for the youths themselves. Discusses eight such books. Discusses difficulties in identity formation that gay and lesbian teens encounter, as well as behaviors that place them at risk. (SR)

  7. Diagnostic Appraisal of Grade 12 Students' Understanding of Reaction Kinetics

    Science.gov (United States)

    Yan, Yaw Kai; Subramaniam, R.

    2016-01-01

    The study explored grade 12 students' understanding of reaction kinetics, a topic which has not been extensively explored in the chemistry education literature at this level. A 3-tier diagnostic instrument with 11 questions was developed--this format is of very recent origin and has been the subject of only a handful of studies. The findings…

  8. Dust Evolution and the Formation of Planetesimals

    Science.gov (United States)

    Birnstiel, T.; Fang, M.; Johansen, A.

    2016-12-01

    The solid content of circumstellar disks is inherited from the interstellar medium: dust particles of at most a micrometer in size. Protoplanetary disks are the environment where these dust grains need to grow at least 13 orders of magnitude in size. Our understanding of this growth process is far from complete, with different physics seemingly posing obstacles to this growth at various stages. Yet, the ubiquity of planets in our galaxy suggests that planet formation is a robust mechanism. This chapter focuses on the earliest stages of planet formation, the growth of small dust grains towards the gravitationally bound "planetesimals", the building blocks of planets. We will introduce some of the key physics involved in the growth processes and discuss how they are expected to shape the global behavior of the solid content of disks. We will consider possible pathways towards the formation of larger bodies and conclude by reviewing some of the recent observational advances in the field.

  9. Understanding Understanding Mathematics. Artificial Intelligence Memo No. 488.

    Science.gov (United States)

    Michener, Edwina Rissland

    This document is concerned with the important extra-logical knowledge that is often outside of traditional discussions in mathematics, and looks at some of the ingredients and processes involved in the understanding of mathematics. The goal is to develop a conceptual framework in which to talk about mathematical knowledge and to understand the…

  10. Temperature controlled 'void' formation

    International Nuclear Information System (INIS)

    Dasgupta, P.; Sharma, B.D.

    1975-01-01

    The nucleation and growth of voids in structural materials during high temperature deformation or irradiation is essentially dependent upon the existence of 'vacancy supersaturation'. The role of temperature dependent diffusion processes in 'void' formation under varying conditions, and the mechanical property changes associated with this microstructure are briefly reviewed. (author)

  11. Formatting Design Dialogues

    DEFF Research Database (Denmark)

    Brandt, Eva; Binder, Thomas; Messeter, Jörn

    2008-01-01

    This article discusses design games as a particular genre for formatting design dialogues. In the first part of the article we review the participatory design literature for game-oriented framings of co-design. We look at what constitutes game and play, we discuss other authors’ use of games...

  12. Triggered star formation

    Czech Academy of Sciences Publication Activity Database

    Palouš, Jan; Ehlerová, Soňa

    2002-01-01

    Roč. 12, - (2002), s. 35-36 ISSN 1405-2059 R&D Projects: GA AV ČR IAA3003705; GA AV ČR KSK1048102 Institutional research plan: CEZ:AV0Z1003909 Keywords : interstellar medium * star formation * HI shells Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  13. PAHs and star formation

    NARCIS (Netherlands)

    Tielens, AGGM; Peeters, E; Bakes, ELO; Spoon, HWW; Hony, S; Johnstone, D; Adams, FC; Lin, DNC; Neufeld, DA; Ostriker, EC

    2004-01-01

    Strong IR emission features at 3.3, 6.2, 7.7, 8.6, and 11.2 mum are a common characteristic of regions of massive star formation. These features are carried by large (similar to 50 C-atom) Polycyclic Aromatic Hydrocarbon molecules which are pumped by the strong FUV photon flux from these stars.

  14. FORMATION CONSTANTS AND THERMODYNAMIC ...

    African Journals Online (AJOL)

    , Ni(II), Cu(II) and Zn(II) ions has been ... A good deal of work has been reported on the preparation and structural investigation of. Schiff base ... Formation constants and thermodynamic parameters of Co, Ni, Cu and Zn complexes. Bull. Chem.

  15. Understanding the Irradiation Behavior of Zirconium Carbide

    Energy Technology Data Exchange (ETDEWEB)

    Motta, Arthur [Pennsylvania State Univ., University Park, PA (United States); Sridharan, Kumar [Univ. of Wisconsin, Madison, WI (United States); Morgan, Dane [Univ. of Wisconsin, Madison, WI (United States); Szlufarska, Izabela [Univ. of Wisconsin, Madison, WI (United States)

    2013-10-11

    Zirconium carbide (ZrC) is being considered for utilization in high-temperature gas-cooled reactor fuels in deep-burn TRISO fuel. Zirconium carbide possesses a cubic B1-type crystal structure with a high melting point, exceptional hardness, and good thermal and electrical conductivities. The use of ZrC as part of the TRISO fuel requires a thorough understanding of its irradiation response. However, the radiation effects on ZrC are still poorly understood. The majority of the existing research is focused on the radiation damage phenomena at higher temperatures (>450{degree}C) where many fundamental aspects of defect production and kinetics cannot be easily distinguished. Little is known about basic defect formation, clustering, and evolution of ZrC under irradiation, although some atomistic simulation and phenomenological studies have been performed. Such detailed information is needed to construct a model describing the microstructural evolution in fast-neutron irradiated materials that will be of great technological importance for the development of ZrC-based fuel. The goal of the proposed project is to gain fundamental understanding of the radiation-induced defect formation in zirconium carbide and irradiation response by using a combination of state-of-the-art experimental methods and atomistic modeling. This project will combine (1) in situ ion irradiation at a specialized facility at a national laboratory, (2) controlled temperature proton irradiation on bulk samples, and (3) atomistic modeling to gain a fundamental understanding of defect formation in ZrC. The proposed project will cover the irradiation temperatures from cryogenic temperature to as high as 800{degree}C, and dose ranges from 0.1 to 100 dpa. The examination of this wide range of temperatures and doses allows us to obtain an experimental data set that can be effectively used to exercise and benchmark the computer calculations of defect properties. Combining the examination of radiation

  16. How do family physicians communicate about cardiovascular risk? Frequencies and determinants of different communication formats

    Directory of Open Access Journals (Sweden)

    Rosemann Thomas

    2011-04-01

    Full Text Available Abstract Background Patients understand information about risk better if it is communicated in numerical or visual formats (e.g. graphs compared to verbal qualifiers only. How frequently different communication formats are used in clinical primary care settings is unknown. Methods We collected socioeconomic and patient understanding data using questionnaires and audio-recorded consultations about cardiovascular disease risk. The frequencies of the communication formats were calculated and multivariate regression analysis of associations between communication formats, patient and general practitioner characteristics, and patient subjective understanding was performed. Results In 73% of 70 consultations, verbal qualifiers were used exclusively to communicate cardiovascular risk, compared to numerical (11% and visual (16% formats. Female GPs and female patient's gender were significantly associated with a higher use of verbal formats compared to visual formats (p = 0.001 and p = 0.039, respectively. Patient subjective understanding was significantly higher in visual counseling compared to verbal counseling (p = 0.001. Conclusions Verbal qualifiers are the most often used communication format, though recommendations favor numerical and visual formats, with visual formats resulting in better understanding than others. Also, gender is associated with the choice of communication format. Barriers against numerical and visual communication formats among GPs and patients should be studied, including gender aspects. Adequate risk communication should be integrated into physicians' education.

  17. Star Formation in low mass galaxies

    Science.gov (United States)

    Mehta, Vihang

    2018-01-01

    Our current hierarchical view of the universe asserts that the large galaxies we see today grew via mergers of numerous smaller galaxies. As evidenced by recent literature, the collective impact of these low mass galaxies on the universe is more substantial than previously thought. Studying the growth and evolution of these low mass galaxies is critical to our understanding of the universe as a whole. Star formation is one of the most important ongoing processes in galaxies. Forming stars is fundamental to the growth of a galaxy. One of the main goals of my thesis is to analyze the star formation in these low mass galaxies at different redshifts.Using the Hubble UltraViolet Ultra Deep Field (UVUDF), I investigate the star formation in galaxies at the peak of the cosmic star formation history using the ultraviolet (UV) light as a star formation indicator. Particularly, I measure the UV luminosity function (LF) to probe the volume-averaged star formation properties of galaxies at these redshifts. The depth of the UVUDF is ideal for a direct measurement of the faint end slope of the UV LF. This redshift range also provides a unique opportunity to directly compare UV to the "gold standard" of star formation indicators, namely the Hα nebular emission line. A joint analysis of the UV and Hα LFs suggests that, on average, the star formation histories in low mass galaxies (~109 M⊙) are more bursty compared to their higher mass counterparts at these redshifts.Complementary to the analysis of the average star formation properties of the bulk galaxy population, I investigate the details of star formation in some very bursty galaxies at lower redshifts selected from Spitzer Large Area Survey with Hyper-Suprime Cam (SPLASH). Using a broadband color-excess selection technique, I identify a sample of low redshift galaxies with bright nebular emission lines in the Subaru-XMM Deep Field (SXDF) from the SPLASH-SXDF catalog. These galaxies are highly star forming and have

  18. Memorandums of Understanding with Australia

    Science.gov (United States)

    In February 2016, U.S. EPA and the Australian Department of Agriculture and Water Resources signed a Memorandum of Understanding on Water. This was an update to the March 2011 Memorandum of Understanding on the same topic. Both documents are available bel

  19. Artistic Understanding and Motivational Characteristics

    Science.gov (United States)

    Lekue, Pablo

    2015-01-01

    This study aims to analyse artistic understanding in primary and secondary education and the relationship between this understanding and motivational characteristics such as goal orientation, engagement in art activities and attitude to art education at school, which determine (according to prior research) learners' academic achievement, in…

  20. Intercultural Understanding: An Interpretive Perspective.

    Science.gov (United States)

    Ting-Toomey, Stella

    Noting that intercultural understanding is a prime construct in the study of intercultural communication, this paper examines two questions that confront all intercultural communication researchers: (1) What are the underlying characteristics of intercultural understanding? and (2) What constitutes an interpretative perspective to intercultural…

  1. Students' Understanding of Quadratic Equations

    Science.gov (United States)

    López, Jonathan; Robles, Izraim; Martínez-Planell, Rafael

    2016-01-01

    Action-Process-Object-Schema theory (APOS) was applied to study student understanding of quadratic equations in one variable. This required proposing a detailed conjecture (called a genetic decomposition) of mental constructions students may do to understand quadratic equations. The genetic decomposition which was proposed can contribute to help…

  2. Bioinstrumentation: Tools for Understanding Life.

    Science.gov (United States)

    Wandersee, James H., Ed.; And Others

    This book was written to help introductory biology teachers gain a basic understanding of contemporary bioinstrumentation and the uses to which it is put in the laboratory. It includes topics that are most basic to understanding the nature of biology. The book is divided into five sections: (1) "Separation and Identification" that includes…

  3. Preservice Teachers' Understanding of Variable

    Science.gov (United States)

    Brown, Sue; Bergman, Judy

    2013-01-01

    This study examines the research on middle school students' understanding of variables and explores preservice elementary and middle school teachers' knowledge of variables. According to research studies, middle school students have limited understanding of variables. Many studies have examined the performance of middle school students and offered…

  4. Galaxy formation: internal mechanisms and cosmological processes

    International Nuclear Information System (INIS)

    Martig, Marie

    2010-01-01

    This thesis is devoted to galaxy formation and evolution in a cosmological context. Cosmological simulations have unveiled two main modes of galaxy growth: hierarchical growth by mergers and accretion of cold gas from cosmic filaments. However, these simulations rarely take into account small scale mechanisms, that govern internal evolution and that are a key ingredient to understand galaxy formation and evolution. Thanks to a new simulation technique that I have developed, I first studied the colors of galaxies, and in particular the reddening of elliptical galaxies. I showed that the gas disk in an elliptical galaxy could be stabilized against star formation because of the galaxy's stellar component being within a spheroid instead of a disk. This mechanism can explain the red colors of some elliptical galaxies that contain a gas disk. I also studied the formation of spiral galaxies: most cosmological simulations cannot explain the formation of Milky Way-like galaxies, i.e. with a large disk and a small bulge. I showed that this issue could be partly solved by taking into account in the simulations the mass loss from evolved stars through stellar winds, planetary nebulae and supernovae explosions. (author) [fr

  5. Plasma formation in TBR

    International Nuclear Information System (INIS)

    Del Bosco, E.

    1981-01-01

    In this work are presented and discussed results of the formation and equilibrium of the plasma current in TBR, a small tokamak, designed and contructed at the Instituto de Fisica of Universidade de Sao Paulo. The measured breakdown curves for H 2 , A and He are compared with the predictions of a simple model with reasonable agreement. The influence of stray magnetic fields in the plasma formation is investigated and conditions are chosen to facilitate the breakdown. The time profile of loop voltage and plasma current for shots with plasma equilibrium are shown. A comparison is made between experimental results and analytical-numerical model for tokamaks discharges with ohmic heating. Reasonable agreement is obtained when Z, effective atomic number, is assumed as a parameter. (Author) [pt

  6. Understanding spermatogenesis is a prerequisite for treatment

    Directory of Open Access Journals (Sweden)

    Schulze Wolfgang

    2003-11-01

    Full Text Available Abstract Throughout spermatogenesis multiplication, maturation and differentiation of germ cells results in the formation of the male gamete. The understanding of spermatogenesis needs detailed informations about the organization of the germinal epithelium, the structure and function of different types of germ cells, endocrine and paracrine cells and mechanisms, intratesticular and extratesticular regulation of spermatogenesis. Normal germ cells must be discriminated from malformed, apoptotic and degenerating germ cells and tumor cells. Identification of the border line between normal and disturbed spermatogenesis substantiate the diagnosis of impaired male fertility. The profound knowledge of the complicate process of spermatogenesis and all cells or cell systems involved with is the prerequisite to develop concepts for therapy of male infertility or to handle germ cells in the management of assisted reproduction.

  7. Understanding Spatial Genome Organization: Methods and Insights

    Directory of Open Access Journals (Sweden)

    Vijay Ramani

    2016-02-01

    Full Text Available The manner by which eukaryotic genomes are packaged into nuclei while maintaining crucial nuclear functions remains one of the fundamental mysteries in biology. Over the last ten years, we have witnessed rapid advances in both microscopic and nucleic acid-based approaches to map genome architecture, and the application of these approaches to the dissection of higher-order chromosomal structures has yielded much new information. It is becoming increasingly clear, for example, that interphase chromosomes form stable, multilevel hierarchical structures. Among them, self-associating domains like so-called topologically associating domains (TADs appear to be building blocks for large-scale genomic organization. This review describes features of these broadly-defined hierarchical structures, insights into the mechanisms underlying their formation, our current understanding of how interactions in the nuclear space are linked to gene regulation, and important future directions for the field.

  8. Mars’ peculiar formation

    Science.gov (United States)

    Woo, Man Yin; Brasser, Ramon; Mojzsis, Stephen; Matsumura, Soko; Ida, Shigeru

    2017-10-01

    The formation of the terrestrial planets is a long standing problem. Mars probably holds the key to solving this mystery because of the substantial amount of data gathered from space missions, martian meteorites and its obvious differences when compared to Earth. Recent elemental and isotopic abundances suggest that Mars’ composition is significantly different from that of Earth. Therefore, Mars should have accreted most of its mass in a region different from Earth’s, most likely further from the Sun. These compositional differences should be explained with planet formation models. We tested the probability of producing a Mars analogue that is compositionally different from Earth in two popular planet formation models: the Grand Tack model with tack locations of 1.5 or 2 AU for Jupiter; and the Classical model in which all the terrestrial planets formed near their current locations. We performed a high number of N-body simulations with initial conditions that are either equal-mass planetary embryos or a semi-analytical approach to oligarch growth. Our results show that the probability of producing a Mars analogue which matches the current mass and orbit of Mars is at most 9% but reduces to mostly about 1% when it mainly accretes its mass further than Mars’ current position of 1.5 AU. Strangely enough, in the Grand Tack model the number of Mars analogues produced is independent of the initial number of planet embryos. Hence, we conclude that both planet formation models have difficulties to explain the observed compositional differences between Earth and Mars.

  9. Alkali metal hydride formation

    International Nuclear Information System (INIS)

    1976-01-01

    The present invention relates to a method of producing alkali metal hydrides by absorbing hydrogen gas under pressure into a mixture of lower alkyl mono amines and alkali metal alkyl amides selected from sodium and potassium amides formed from said amines. The present invention also includes purification of a mixture of the amines and amides which contain impurities, such as is used as a catalytic exchange liquid in the enrichment of deuterium, involving the formation of the alkali metal hydride

  10. Isothermal Martensite Formation

    DEFF Research Database (Denmark)

    Villa, Matteo

    are chosen to investigate time dependent martensite formation. Among them, a Fe-11wt%Ni-0.6wt%C model alloy and Fe-1.6wt%Cr-1wt%C (AISI 52100), Fe-17wt%Cr-7wt%Ni (AISI 631) and Fe-16wt%Cr-5wt%Ni (AISI 630) commercial steels. The investigation was performed with in situ magnetometry, dilatometry, synchrotron...

  11. Symbol Formation Reconsidered

    DEFF Research Database (Denmark)

    Wagoner, Brady

    2013-01-01

    begins with a brief outline and contextualization of the book as well as of the articles that this special issue comprises. The first two articles were written by contributors who were part of the Werner era at Clark University. They explore the key concepts of the organismic and development, and situate...... the organismic-developmental approach to fields only touched in Symbol formation, such as magical practices, social structures, pictures and gesture....

  12. Formation of TRAPPIST-1

    Science.gov (United States)

    Ormel, C. W.; Liu, B.; Schoonenberg, D.

    2017-09-01

    We present a model for the formation of the recently-discovered TRAPPIST-1 planetary system. In our scenario planets form in the interior regions, by accretion of mm to cm-size particles (pebbles) that drifted from the outer disk. This scenario has several advantages: it connects to the observation that disks are made up of pebbles, it is efficient, it explains why the TRAPPIST-1 planets are ˜Earth mass, and it provides a rationale for the system's architecture.

  13. Methemoglobin formation by paraquat.

    OpenAIRE

    Watanabe, Shinsaku; Ogata, Masana

    1982-01-01

    Paraquat is a broad spectrum herbicide known to be highly lethal to man and animals. Its toxicity is characterized by acute lung injury. Paraquat produces such toxic effects through the generation of the superoxide anion according to one proposed mechanism. The present experiment, methemoglobin formation was demonstrated after incubation of oxyhemoglobin with paraquat. The generation of the superoxide anion through the interaction of oxyhemoglobin with paraquat was suggested by chemiluminesce...

  14. Formate-assisted pyrolysis

    Science.gov (United States)

    DeSisto, William Joseph; Wheeler, Marshall Clayton; van Heiningen, Adriaan R. P.

    2015-03-17

    The present invention provides, among other thing, methods for creating significantly deoxygenated bio-oils form biomass including the steps of providing a feedstock, associating the feedstock with an alkali formate to form a treated feedstock, dewatering the treated feedstock, heating the dewatered treated feedstock to form a vapor product, and condensing the vapor product to form a pyrolysis oil, wherein the pyrolysis oil contains less than 30% oxygen by weight.

  15. Engram Formation in Psychiatric Disorders

    Directory of Open Access Journals (Sweden)

    Peter J. Gebicke-Haerter

    2014-05-01

    Full Text Available Environmental factors substantially influence beginning and progression of mental illness, reinforcing or reducing the consequences of genetic vulnerability. Often initiated by early traumatic events, engrams or memories are formed that may give rise to a slow and subtle progression of psychiatric disorders. The large delay between beginning and time of onset (diagnosis may be explained by efficient compensatory mechanisms observed in brain metabolism that use optional pathways in highly redundant molecular interactions.To this end, research has to deal with mechanisms of learning and long-term memory formation, which involves a epigenetic changes, b altered neuronal activities and c changes in neuron-glia communication. On the epigenetic level, apparently DNA-methylations are more stable than histone modifications, although both closely interact. Neuronal activities basically deliver digital information, which clearly can serve as basis for memory formation (LTP. However, research in this respect has long time neglected the importance of glia. They are more actively involved in the control of neuronal activities than thought before. They can both reinforce and inhibit neuronal activities by transducing neuronal information from frequency-encoded to amplitude and frequency-modulated calcium wave patterns spreading in the glial syncytium by use of gap junctions. In this way, they serve integrative functions. In conclusion, we are dealing with two concepts of encoding information that mutually control each other and synergize: a digital (neuronal and a wave-like (glial computing, forming neuron-glia functional units with inbuilt feedback loops to maintain balance of excitation and inhibition. To better understand mental illness, we have to gain more insight into the dynamics of adverse environmental impact on those cellular and molecular systems. This report summarizes existing knowledge and draws some outline about further research in molecular

  16. Understanding Disabilities & Online Student Success

    Science.gov (United States)

    Betts, Kristen; Welsh, Bill; Pruitt, Cheryl; Hermann, Kelly; Dietrich, Gaeir; Trevino, Jorge G.; Watson, Terry L.; Brooks, Michael L.; Cohen, Alex H.; Coombs, Norman

    2013-01-01

    Online learning has been growing at an exponential rate over the past decade, providing new opportunities for students seeking quality courses and programs offered through flexible formats. However, as higher education continues to expand online offerings, services must be expanded simultaneously to support all students. This article focuses on…

  17. Understanding organizational change for alliancing

    NARCIS (Netherlands)

    B.M. Keers, Bianca; C. van Fenema, Paul; Zijm, Henk

    2017-01-01

    Purpose: The purpose of this paper is to examine an organization’s operational alignment in the process of alliance formation. Design/methodology/approach: A literature study was conducted on the strategic importance of assessing and aligning organizations’ operations for alliancing. Furthermore, an

  18. Drawing and Writing in Digital Science Notebooks: Sources of Formative Assessment Data

    Science.gov (United States)

    Shelton, Angi; Smith, Andrew; Wiebe, Eric; Behrle, Courtney; Sirkin, Ruth; Lester, James

    2016-01-01

    Formative assessment strategies are used to direct instruction by establishing where learners' understanding is, how it is developing, informing teachers and students alike as to how they might get to their next set of goals of conceptual understanding. For the science classroom, one rich source of formative assessment data about scientific…

  19. Combustion chemistry and formation of pollutants; Chimie de la combustion et formation des polluants

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    This book of proceedings reports on 7 papers on combustion chemistry and formation of pollutants presented during the workshop organized by the `Combustion and Flames` section of the French society of thermal engineers. The chemistry of combustion is analyzed in various situations such as: turbojet engines, spark ignition engines, industrial burners, gas turbines etc... Numerical simulation is used to understand the physico-chemical processes involved in combustion, to describe the kinetics of oxidation, combustion and flame propagation, and to predict the formation of pollutants. (J.S.)

  20. Understanding marketing decision-making

    NARCIS (Netherlands)

    B. Wierenga (Berend)

    2012-01-01

    textabstractWhile a whole range of factors influences the outcomes of a marketing policy, it is managerial decision-making that can really make a difference. A clearer understanding of how marketers make decisions should therefore improve their quality.

  1. Challenges in human behavior understanding

    NARCIS (Netherlands)

    Salah, A.A.; Gevers, T.; Sebe, N.; Vinciarelli, A.

    2010-01-01

    Recent advances in pattern recognition has allowed computer scientists and psychologists to jointly address automatic analysis of of human behavior via computers. The Workshop on Human Behavior Understanding at the International Conference on Pattern Recognition explores a number of different

  2. Know the Facts: Understand Concussion

    Centers for Disease Control (CDC) Podcasts

    2010-03-17

    This podcast discusses concussions and provides information to help people better understand concussion.  Created: 3/17/2010 by National Center for Injury Prevention and Control (NCIPC).   Date Released: 3/17/2010.

  3. Understanding Pregnancy and Birth Issues

    Science.gov (United States)

    ... Home Current Issue Past Issues Understanding Pregnancy and Birth Issues Past Issues / Winter 2008 Table of Contents ... about NICHD preeclampsia research in the sidebar.) Preterm Birth Preterm (premature) birth is birth before the baby ...

  4. Understanding your health care costs

    Science.gov (United States)

    ... ency/patientinstructions/000878.htm Understanding your health care costs To use the sharing features on this page, ... on out-of-pocket costs. Out-of-Pocket Costs The good news is there is a limit ...

  5. Antihistamines: Understanding Your OTC Options

    Science.gov (United States)

    ... CorrectlyPain Relievers: Understanding Your OTC OptionsAntacids and Acid Reducers: OTC Relief for Heartburn and Acid RefluxOTC Cough ... Loss and Diet Plans Nutrients and Nutritional Info Sugar and Sugar Substitutes Exercise and Fitness Exercise Basics ...

  6. Understanding ADHD: Symptoms in Children

    Science.gov (United States)

    ... this page please turn JavaScript on. Feature: Understanding ADHD Symptoms In Children Past Issues / Spring 2014 Table ... hyperactivity, and impulsivity are the key behaviors of ADHD. It is normal for all children to be ...

  7. Ayurgenomics: Understanding human individuality through ...

    Indian Academy of Sciences (India)

    mitali

    Ayurgenomics: Understanding human individuality through integration of. Ayurveda and Genomics for stratified medicine. Mitali Mukerji. Programme Director- CSIR-TRISUTRA. (Translational Research and Innovative Science Through Ayurgenomics). & Scientist CSIR-IGIB. Public health Modern medicine. Ayurveda others ...

  8. Understanding IT for Dispute Resolution

    Directory of Open Access Journals (Sweden)

    Dory Reiling

    2011-04-01

    Full Text Available Judges and judiciaries do not understand information technology (IT. This idea crops up quite often in discussions about IT for courts. The perceived slow rate of IT adoption in courts is explained by this lack of understanding. To my mind, this is not the main issue. What needs to be understood first is at the other end of the spectrum: how courts process information.

  9. Liposome formation in microgravity

    Science.gov (United States)

    Claassen, D. E.; Spooner, B. S.

    Liposomes are artificial vesicles with a phospholipid bilayer membrane. The formation of liposomes is a self-assembly process that is driven by the amphipathic nature of phospholipid molecules and can be observed during the removal of detergent from phospholipids dissolved in detergent micelles. As detergent concentration in the mixed micelles decreases, the non-polar tail regions of phospholipids produce a hydrophobic effect that drives the micelles to fuse and form planar bilayers in which phospholipids orient with tail regions to the center of the bilayer and polar head regions to the external surface. Remaining detergent molecules shield exposed edges of the bilayer sheet from the aqueous environment. Further removal of detergent leads to intramembrane folding and membrane vesiculation, forming liposomes. We have observed that the formation of liposomes is altered in microgravity. Liposomes that were formed at 1-g did not exceed 150 nm in diameter, whereas liposomes that were formed during spaceflight exhibited diameters up to 2000 nm. Using detergent-stabilized planar bilayers, we determined that the stage of liposome formation most influenced by gravity is membrane vesiculation. In addition, we found that small, equipment-induced fluid disturbances increased vesiculation and negated the size-enhancing effects of microgravity. However, these small disturbances had no effect on liposome size at 1-g, likely due to the presence of gravity-induced buoyancy-driven fluid flows (e.g., convection currents). Our results indicate that fluid disturbances, induced by gravity, influence the vesiculation of membranes and limit the diameter of forming liposomes.

  10. Formation control of AAUSHIP

    DEFF Research Database (Denmark)

    Østergaard, Nick; Dam, Jeppe; Larsen, Jesper Abildgaard

    2015-01-01

    Many maritime mapping tasks are today carried out by large research ships, which are very costly to operate. As a way to overcome this, a number of small surveying vessels have been developed called AAUSHIP. In order to efficiently map the an area with such smaller vessels, it is important that s...... that several vessels are able to corporate on the task at hand. In this paper, the developed formation control strategy for the AAUSHIP series of vessels is presented, along with simulation results, which confirms, that the algorithm works as intended....

  11. Bouyei word formation

    Directory of Open Access Journals (Sweden)

    Attasith Boonsawasd

    2012-12-01

    Full Text Available The Bouyei language is divided into three vernaculars, the southern vernacular, the central vernacular and the southwestern vernacular. This paper aims to describe the lexicology of the southern vernacular of the Bouyei language focusing on word formation process. Bouyei words are formed by affixing, compounding and reduplicating. First, the affixation consists of prefixing and suffixing. Infixing is not found in this language. Second, the compound is divided into the semantic and syntactic compound. Finally, the reduplication is divided into the simple and complex reduplication. The simple reduplication is normally used to emphasize the meaning of the root or to indicate plurality.

  12. Democracy and formation

    DEFF Research Database (Denmark)

    Huggler, Jørgen

    to nature, Schlegel appeals to culture and political experience and political formation, in order to make the world more peaceful. He opposes with heavy arguments the Kantian distinction between republicanism and democracy. Instead he gives quite good reasons for a more important distinction between...... of the structure of political autonomy in a political social contract (Ingeborg Mauss). Against Kant, the thinker of political continuity, Schlegel presents historically well informed reflections on the beginning and the end of political legitimacy. Dictatorship can be legitimate, states of emergency are found...

  13. Formation and Assembly of Massive Star Clusters

    Science.gov (United States)

    McMillan, Stephen

    The formation of stars and star clusters is a major unresolved problem in astrophysics. It is central to modeling stellar populations and understanding galaxy luminosity distributions in cosmological models. Young massive clusters are major components of starburst galaxies, while globular clusters are cornerstones of the cosmic distance scale and represent vital laboratories for studies of stellar dynamics and stellar evolution. Yet how these clusters form and how rapidly and efficiently they expel their natal gas remain unclear, as do the consequences of this gas expulsion for cluster structure and survival. Also unclear is how the properties of low-mass clusters, which form from small-scale instabilities in galactic disks and inform much of our understanding of cluster formation and star-formation efficiency, differ from those of more massive clusters, which probably formed in starburst events driven by fast accretion at high redshift, or colliding gas flows in merging galaxies. Modeling cluster formation requires simulating many simultaneous physical processes, placing stringent demands on both software and hardware. Simulations of galaxies evolving in cosmological contexts usually lack the numerical resolution to simulate star formation in detail. They do not include detailed treatments of important physical effects such as magnetic fields, radiation pressure, ionization, and supernova feedback. Simulations of smaller clusters include these effects, but fall far short of the mass of even single young globular clusters. With major advances in computing power and software, we can now directly address this problem. We propose to model the formation of massive star clusters by integrating the FLASH adaptive mesh refinement magnetohydrodynamics (MHD) code into the Astrophysical Multi-purpose Software Environment (AMUSE) framework, to work with existing stellar-dynamical and stellar evolution modules in AMUSE. All software will be freely distributed on-line, allowing

  14. Analyzing social policy: multiple perspectives for critically understanding and evaluating policy

    National Research Council Canada - National Science Library

    O'Connor, Mary Katherine; Netting, F. Ellen

    2011-01-01

    "This unique volume outlines the different frameworks of policy analysis and explains how readers can use research and critical thinking skills to understand the different models from their formation...

  15. SPMHD simulations of Structure Formation

    Science.gov (United States)

    Barnes, David J.; On, Alvina Y. L.; Wu, Kinwah; Kawata, Daisuke

    2018-02-01

    The intracluster medium of galaxy clusters is permeated by μ {G} magnetic fields. Observations with current and future facilities have the potential to illuminate the role of these magnetic fields play in the astrophysical processes of galaxy clusters. To obtain a greater understanding of how the initial seed fields evolve to the magnetic fields in the intracluster medium requires magnetohydrodynamic simulations. We critically assess the current Smoothed Particle Magneto-Hydrodynamics (SPMHD) schemes, especially highlighting the impact of a hyperbolic divergence cleaning scheme and artificial resistivity switch on the magnetic field evolution in cosmological simulations of the formation of a galaxy cluster using the N-body/SPMHD code GCMHD++. The impact and performance of the cleaning scheme and two different schemes for the artificial resistivity switch is demonstrated via idealized test cases and cosmological simulations. We demonstrate that the hyperbolic divergence cleaning scheme is effective at suppressing the growth of the numerical divergence error of the magnetic field and should be applied to any SPMHD simulation. Although the artificial resistivity is important in the strong field regime, it can suppress the growth of the magnetic field in the weak field regime, such as galaxy clusters. With sufficient resolution, simulations with divergence cleaning can reproduce observed magnetic fields. We conclude that the cleaning scheme alone is sufficient for galaxy cluster simulations, but our results indicate that the SPMHD scheme must be carefully chosen depending on the regime of the magnetic field.

  16. Understanding and Design of Polymer Device Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kahn, Antoine [Princeton Univ., NJ (United States)

    2015-10-26

    The research performed under grant DE-FG02-04ER46165 between May 2008 and April 2011 focused on the understanding and control of interfaces of organic semiconductors in general, and polymer interfaces more specifically. This work was a joined effort by three experimentalists and a theoretician. Emphasis was placed on the determination of the electronic structure of these interfaces, i.e. the relative energy position of molecular levels across these interfaces. From these electronic structures depend the injection, extraction and transport of charge carriers into, from and across, respectively, all (opto)electronic devices made of these semiconductors. A significant fraction of our work focused on ways to modify and optimize interfaces, for example via chemical doping of the semiconductors to reduce interface energy barriers or via deposition of ultra-thin work function-reducing polymer or self-assembled monolayers of dipolar molecules. Another significant fraction of our work was devoted to exploring alternate and unconventional interface formation methods, in particular the soft-contact lamination of both metal contacts and polymer overlayers on top of polymer films. These methods allowed us to better understand the impact of hot metal atom evaporation on a soft organic surface, as well as the key mechanisms that control the energetics of polymer/polymer heterojunctions. Finally, a significant fraction of the research was directed to understanding the electronic structure of buried polymer heterojunctions, in particular within donor/acceptor blends of interest in organic photovoltaic applications. The work supported by this grant resulted in 17 publications in some of the best peer-reviewed journals of the field, as well as numerous presentations at US and international conferences.

  17. Child's understanding of television programmes

    Directory of Open Access Journals (Sweden)

    Martina Peštaj

    2011-01-01

    Full Text Available In the last decade, we have witnessed an unimaginable progress of the electronic media. The television takes the first place by its availability, importance and popularity, both with adults and with children. It has become the focal point of family interaction and is progressively taking on a key role in the process of children's socialization. Various research has proven that children begin watching television as babies and that toddlers are already accustomed and constant viewers. During their development, they become increasingly competent to understand and to use the television media, while the differences in the perception of television contents are mainly conditioned by the period of early childhood. The process of preschool child's understanding of media information goes from concrete to abstract and on two levels at the same time: understanding of formal features and understanding of content. Both levels have important role in child's understanding of the world, what could be observed in forming of gender stereotypes, where, as researches show, the television has a special influence.

  18. [Intersubjectivity: Between Explanation and Understanding].

    Science.gov (United States)

    Cely Ávila, Flor Emilce

    2014-03-01

    The discussion on explanation and understanding has led to a division in the sciences, based on what is considered to be inherent to each of the domains. The task of the natural sciences would be the explanation, while that of the social sciences would be understanding or interpretation.There is a line of work that currently seeks to overcome the methodological dualism and to propose more interdisciplinary studies, such as the studies on emergence of the mental in the framework of intersubjective relationships. In particular, the concept of intersubjectivity defended by the phenomenology as an embodied practice, is being supported by the results of investigations carried out on the basis of the cognitive neuroscience and developmental psychology. Authors from different roots, such as J. Bruner and S. Gallagher propose considering these types of interdisciplinary collaboration as a possible way to integrate the traditions of the explanation and understanding. The purpose of this paper is to analyze to what extent this collaboration between phenomenology and sciences, particularly on the subject of understanding others and their relevance for the understanding of certain psychopathologies, has allowed to close the gap that had opened in the nineteenth century between these traditions. Copyright © 2014 Asociación Colombiana de Psiquiatría. Publicado por Elsevier España. All rights reserved.

  19. Semantic Borders and Incomplete Understanding.

    Science.gov (United States)

    Silva-Filho, Waldomiro J; Dazzani, Maria Virgínia

    2016-03-01

    In this article, we explore a fundamental issue of Cultural Psychology, that is our "capacity to make meaning", by investigating a thesis from contemporary philosophical semantics, namely, that there is a decisive relationship between language and rationality. Many philosophers think that for a person to be described as a rational agent he must understand the semantic content and meaning of the words he uses to express his intentional mental states, e.g., his beliefs and thoughts. Our argument seeks to investigate the thesis developed by Tyler Burge, according to which our mastery or understanding of the semantic content of the terms which form our beliefs and thoughts is an "incomplete understanding". To do this, we discuss, on the one hand, the general lines of anti-individualism or semantic externalism and, on the other, criticisms of the Burgean notion of incomplete understanding - one radical and the other moderate. We defend our understanding that the content of our beliefs must be described in the light of the limits and natural contingencies of our cognitive capacities and the normative nature of our rationality. At heart, anti-individualism leads us to think about the fact that we are social creatures, living in contingent situations, with important, but limited, cognitive capacities, and that we receive the main, and most important, portion of our knowledge simply from what others tell us. Finally, we conclude that this discussion may contribute to the current debate about the notion of borders.

  20. Urbanization and slum formation.

    Science.gov (United States)

    Ooi, Giok Ling; Phua, Kai Hong

    2007-05-01

    The formation of slums need not be inevitable with rapid urbanization. Such an argument appears to be contradicted by evidence of large slum populations in a large number of developing countries and particularly in rapidly urbanizing regions like Asia. The evidence discussed suggests that city authorities faced with rapid urban development lack the capacity to cope with the diverse demands for infrastructural provision to meet economic and social needs. Not only are strategic planning and intervention major issues in agenda to manage rapid urbanization, but city governments are not effectively linking the economic development trajectory to implications for urban growth and, hence, housing needs. In the following discussion, a case study is presented in support of the argument that city governments have to first recognize and then act to establish the link that is crucial between economic development, urban growth, and housing. This is the agendum that has been largely neglected by city and national governments that have been narrowly focused on economic growth with the consequent proliferation of slum formation as a housing solution.

  1. Understanding Number Sequences Leads to Understanding Mathematics Concepts

    Science.gov (United States)

    Pasnak, Robert; Schmerold, Katrina Lea; Robinson, Melissa Fetterer; Gadzichowski, K. Marinka; Bock, Allison M.; O'Brien, Sarah Eva; Kidd, Julie K.; Gallington, Deb A.

    2016-01-01

    Ninety-six first grade students in an urban school system were tested in October and May on reading, mathematics, and their understanding of sequences of letters and numbers. A time lag analysis was subsequently conducted. In such analyses, cross-correlations between the first measurement of one variable and the second measurement of another are…

  2. Accessing and Understanding MODIS Data

    Science.gov (United States)

    Leptoukh, Gregory; Jenkerson, Calli B.; Jodha, Siri

    2003-01-01

    The National Aeronautics and Space Administration (NASA) launched the Terra satellite in December 1999, as part of the Earth Science Enterprise promotion of interdisciplinary studies of the integrated Earth system. Aqua, the second satellite from the series of EOS constellation, was launched in May 2002. Both satellites carry the MODerate resolution Imaging Spectroradiometer (MODIS) instrument. MODIS data are processed at the Goddard Space Flight Center, Greenbelt, MD, and then archived and distributed by the Distributed Active Archive Centers (DAACs). Data products from the MODIS sensors present new challenges to remote sensing scientists due to specialized production level, data format, and map projection. MODIS data are distributed as calibrated radiances and as higher level products such as: surface reflectance, water-leaving radiances, ocean color and sea surface temperature, land surface kinetic temperature, vegetation indices, leaf area index, land cover, snow cover, sea ice extent, cloud mask, atmospheric profiles, aerosol properties, and many other geophysical parameters. MODIS data are stored in HDF- EOS format in both swath format and in several different map projections. This tutorial guides users through data set characteristics as well as search and order interfaces, data unpacking, data subsetting, and potential applications of the data. A CD-ROM with sample data sets, and software tools for working with the data will be provided to the course participants.

  3. Students' understanding of quadratic equations

    Science.gov (United States)

    López, Jonathan; Robles, Izraim; Martínez-Planell, Rafael

    2016-05-01

    Action-Process-Object-Schema theory (APOS) was applied to study student understanding of quadratic equations in one variable. This required proposing a detailed conjecture (called a genetic decomposition) of mental constructions students may do to understand quadratic equations. The genetic decomposition which was proposed can contribute to help students achieve an understanding of quadratic equations with improved interrelation of ideas and more flexible application of solution methods. Semi-structured interviews with eight beginning undergraduate students explored which of the mental constructions conjectured in the genetic decomposition students could do, and which they had difficulty doing. Two of the mental constructions that form part of the genetic decomposition are highlighted and corresponding further data were obtained from the written work of 121 undergraduate science and engineering students taking a multivariable calculus course. The results suggest the importance of explicitly considering these two highlighted mental constructions.

  4. Finite Element Modeling of Burr Formation in Metal Cutting

    OpenAIRE

    Min, Sangkee; Dornfeld, David; Kim, J.; Shyu, B.

    2007-01-01

    In order to advance understanding of the burr formation process, a series of finite element models are introduced. First a finite element model of the burr formation of two-dimensional orthogonal cutting is introduced and validated with experimental observations. A detailed and thorough examination of the drilling burr forming process is undertaken. This information is then used in the construction of an analytical model and, leads to development of a three-dimensional finite element mode...

  5. The multifaceted planetesimal formation process

    DEFF Research Database (Denmark)

    Johansen, Anders; Blum, Jürgen; Tanaka, Hidekazu

    2013-01-01

    -Neptunian objects and comets provide a unique record of the physical conditions in the solar nebula. Debris from planetesimal collisions around other stars signposts that the planetesimal formation process, and hence planet formation, is ubiquitous in the Galaxy. The planetesimal formation stage extends from...

  6. Designing for informed group formation

    DEFF Research Database (Denmark)

    Nicolajsen, Hanne Westh; Juel Jacobsen, Alice; Riis, Marianne

    2012-01-01

    A new design ―project preparation‖ preparing for the group formation in problem based project work is proposed and investigated. The main problem is to overcome group formation based on existing relations. The hypothesis is that theme development and group formation are somewhat counterproductive...

  7. Restoring formation after leaching process

    International Nuclear Information System (INIS)

    Barrett, R.B.

    1983-01-01

    A method of restoring a formation which had uranium and other mineral values extracted by an alkaline lixiviant comprises introducing a source of phosphate in an amount sufficient to lower the level of soluble uranium compounds below that previously existing in the formation by the formation of insoluble uranium phosphate compounds

  8. Histopathology Predicts the Mechanism of Stone Formation

    Science.gov (United States)

    Evan, Andrew P.

    2007-04-01

    About 5% of American women and 12% of men will develop a kidney stone at some time in their life and these numbers appear to be on the rise. Despite years of scientific research into the mechanisms of stone formation and growth, limited advances have been made until recently. Randall's original observations and thoughts on the mechanisms for kidney stone formation have been validated for idiopathic calcium oxalate stone formers (ICSF) but not for most other stone forming groups. Our current studies on selected groups of human stone formers using intraoperative papillary biopsies has shown overwhelming evidence for the presence of Randall's plaque in ICSF and that stone formation and growth are exclusively linked to its availability to urinary ions and proteins. Intense investigation of the plaque-stone junction is needed if we are to understand the factors leading to the overgrowth process on exposed regions of plaque. Such information should allow the development of treatment strategies to block stone formation in ICSF patients. Patients who form brushite stones, or who form apatite stones because of distal renal tubular acidosis (dRTA), or patients with calcium oxalate stones due to obesity bypass procedures, or patients with cystinuria, get plugged inner medullary collecting ducts (IMCD) which leads to total destruction of the lining cells and focal sites of interstitial fibrosis. These stone formers have plaque but at levels equal to or below non-stone formers, which would suggest that they form stones by a different mechanism than do ICSF patients.

  9. Activation of PAD4 in NET formation

    Directory of Open Access Journals (Sweden)

    Amanda eRohrbach

    2012-11-01

    Full Text Available Peptidyl arginine deiminases, or PADs, convert arginine residues to the non-ribosomally encoded amino acid citrulline in a variety of protein substrates. PAD4 is expressed in granulocytes and is essential for the formation of neutrophil extracellular traps (NETs via PAD4-mediated histone citrullination. Citrullination of histones is thought to promote NET formation by inducing chromatin decondensation and facilitating the expulsion of chromosomal DNA that is coated with antimicrobial molecules. Numerous stimuli have been reported to lead to PAD4 activation and NET formation. However, how this signaling process proceeds and how PAD4 becomes activated in cells is largely unknown. Herein, we describe the various stimuli and signaling pathways that have been implicated in PAD4 activation and NET formation, including the role of reactive oxygen species generation. To provide a foundation for the above discussion, we first describe PAD4 structure and function, and how these studies led to the development of PAD-specific inhibitors. A comprehensive survey of the receptors and signaling pathways that regulate PAD4 activation will be important for our understanding of innate immunity, and the identification of signaling intermediates in PAD4 activation may also lead to the generation of pharmaceuticals to target NET-related pathogenesis.

  10. Messenger RNA 3' end formation in plants.

    Science.gov (United States)

    Hunt, A G

    2008-01-01

    Messenger RNA 3' end formation is an integral step in the process that gives rise to mature, translated messenger RNAs in eukaryotes. With this step, a pre-messenger RNA is processed and polyadenylated, giving rise to a mature mRNA bearing the characteristic poly(A) tract. The poly(A) tract is a fundamental feature of mRNAs, participating in the process of translation initiation and being the focus of control mechanisms that define the lifetime of mRNAs. Thus messenger RNA 3' end formation impacts two steps in mRNA biogenesis and function. Moreover, mRNA 3' end formation is something of a bridge that integrates numerous other steps in mRNA biogenesis and function. While the process is essential for the expression of most genes, it is also one that is subject to various forms of regulation, such that both quantitative and qualitative aspects of gene expression may be modulated via the polyadenylation complex. In this review, the current status of understanding of mRNA 3' end formation in plants is discussed. In particular, the nature of mRNA 3' ends in plants is reviewed, as are recent studies that are beginning to yield insight into the functioning and regulation of plant polyadenylation factor subunits.

  11. Image understanding using sparse representations

    CERN Document Server

    Thiagarajan, Jayaraman J; Turaga, Pavan; Spanias, Andreas

    2014-01-01

    Image understanding has been playing an increasingly crucial role in several inverse problems and computer vision. Sparse models form an important component in image understanding, since they emulate the activity of neural receptors in the primary visual cortex of the human brain. Sparse methods have been utilized in several learning problems because of their ability to provide parsimonious, interpretable, and efficient models. Exploiting the sparsity of natural signals has led to advances in several application areas including image compression, denoising, inpainting, compressed sensing, blin

  12. Understanding quantitative research: part 1.

    Science.gov (United States)

    Hoe, Juanita; Hoare, Zoë

    This article, which is the first in a two-part series, provides an introduction to understanding quantitative research, basic statistics and terminology used in research articles. Critical appraisal of research articles is essential to ensure that nurses remain up to date with evidence-based practice to provide consistent and high-quality nursing care. This article focuses on developing critical appraisal skills and understanding the use and implications of different quantitative approaches to research. Part two of this article will focus on explaining common statistical terms and the presentation of statistical data in quantitative research.

  13. Condensation Mechanism of Hydrocarbon Field Formation.

    Science.gov (United States)

    Batalin, Oleg; Vafina, Nailya

    2017-08-31

    Petroleum geology explains how hydrocarbon fluids are generated, but there is a lack of understanding regarding how oil is expelled from source rocks and migrates to a reservoir. To clarify the process, the multi-layer Urengoy field in Western Siberia was investigated. Based on this example, we have identified an alternative mechanism of hydrocarbon field formation, in which oil and gas accumulations result from the phase separation of an upward hydrocarbon flow. There is evidence that the flow is generated by the gases released by secondary kerogen destruction. This study demonstrates that oil components are carried by the gas flow and that when the flow reaches a low-pressure zone, it condenses into a liquid with real oil properties. The transportation of oil components in the gas flow provides a natural explanation for the unresolved issues of petroleum geology concerning the migration process. The condensation mechanism can be considered as the main process of oil field formation.

  14. Formation of the Isthmus of Panama

    Science.gov (United States)

    O'Dea, Aaron; Aguilera, Orangel; Aubry, Marie-Pierre; Berggren, William A.; Cione, Alberto L.; Coates, Anthony G.; Collins, Laurel S.; Coppard, Simon E.; Cozzuol, Mario A.; de Queiroz, Alan; Duque-Caro, Herman; Eytan, Ron I.; Farris, David W.; Gasparini, German M.; Grosmman, Ethan L.; Jackson, Jeremy B. C.; Johnson, Kenneth G.; Keigwin, Lloyd D.; Knowlton, Nancy; Leigh, Egbert G.; Leonard-Pingel, Jill S.; Lessios, Hailaos A.; Marko, Peter B.; Norris, Richard D.; Rachello-Dolmen, Paola G.; Restrepo-Moreno, Sergio A.; Soibelzon, Leopoldo; Stallard, Robert F.; Todd, Jonathan A.; Vermeiju, Geerat J.; Woodburne, Michael O.

    2016-01-01

    The formation of the Isthmus of Panama stands as one of the greatest natural events of the Cenozoic, driving profound biotic transformations on land and in the oceans. Some recent studies suggest that the Isthmus formed many millions of years earlier than the widely recognized age of approximately 3 million years ago (Ma), a result that if true would revolutionize our understanding of environmental, ecological, and evolutionary change across the Americas. To bring clarity to the question of when the Isthmus of Panama formed, we provide an exhaustive review and reanalysis of geological, paleontological, and molecular records. These independent lines of evidence converge upon a cohesive narrative of gradually emerging land and constricting seaways, with formation of the Isthmus of Panama sensu stricto around 2.8 Ma. The evidence used to support an older isthmus is inconclusive, and we caution against the uncritical acceptance of an isthmus before the Pliocene.

  15. Recipes for planet formation

    Science.gov (United States)

    Meyer, Michael R.

    2009-11-01

    Anyone who has ever used baking soda instead of baking powder when trying to make a cake knows a simple truth: ingredients matter. The same is true for planet formation. Planets are made from the materials that coalesce in a rotating disk around young stars - essentially the "leftovers" from when the stars themselves formed through the gravitational collapse of rotating clouds of gas and dust. The planet-making disk should therefore initially have the same gas-to-dust ratio as the interstellar medium: about 100 to 1, by mass. Similarly, it seems logical that the elemental composition of the disk should match that of the star, reflecting the initial conditions at that particular spot in the galaxy.

  16. Determinants for gallstone formation

    DEFF Research Database (Denmark)

    Shabanzadeh, Daniel Monsted; Sorensen, Lars Tue; Jørgensen, Torben

    2016-01-01

    associations were found for blood pressure, smoking, alcohol consumption, HDL cholesterol, or triglycerides in meta-analyses. Conclusions: Age, female sex, BMI, non-HDL cholesterol, and polyps are independent determinants for gallstone formation. Incident gallstones and the metabolic syndrome share common risk...... on a prospective protocol, a systematic review of the literature was performed identifying all articles dealing with determinants of incident gallstones. Meta-analyses of comparable determinants were performed through fixed effect models. Results: Participants with no gallstones at baseline and with at least one...... re-examination were followed-up completely (mean 11.6 years, N = 2848). The overall cumulative incidence of gallstones was 0.60% per year. Independent positive determinants for incident gallstones were age, female sex, non-high density lipoprotein (non-HDL) cholesterol, and gallbladder polyps...

  17. Formation fracturing with foam

    Energy Technology Data Exchange (ETDEWEB)

    Blauer, R.E.; Kohlhaas, C.A.

    1974-01-01

    Over 60 wells have been treated with hydraulic fracturing techniques, with foam as the fracturing fluid. These foams contained as much as 95% gaseous phase; most treatments used foams with gas contents in the 65% to 85% range. Foam has several desirable properties for use as a fracturing fluid: high sand-carrying and sand-suspending capability, low fluid loss, low hydrostatic head, low pressure drops due to friction, quick fluid recovery, low formation damage, and no reduction of fracture conductivity due to fluid ingredients. Most applications of foam as a fracturing fluid have been in low permeability gas reservoirs. However, several oil reservoirs also have been successfully treated. Cost of the treatment is approx. the same or slightly less than a treatment with conventional fluids of comparable volume and rate. (25 refs.)

  18. Standardizing exchange formats

    International Nuclear Information System (INIS)

    Lemmel, H.D.; Schmidt, J.J.

    1992-01-01

    An international network of co-operating data centres is described who maintain identical data bases which are simultaneously updated by an agreed data exchange procedure. The agreement covers ''data exchange formats'' which are compatible to the centres' internal data storage and retrieval systems which remain different, optimized at each centre to the available computer facilities and to the needs of the data users. Essential condition for the data exchange is an agreement on common procedures for the data exchange is an agreement on common procedures for the data compilation, including critical data analysis and validation. The systems described (''EXFOR'', ''ENDF'', ''CINDA'') are used for ''nuclear reaction data'', but the principles used for data compilation and exchange should be valid also for other data types. (author). 24 refs, 4 figs

  19. Pebble pile-up and planetesimal formation at the snow line

    Science.gov (United States)

    Drazkowska, J.

    2017-09-01

    The planetesimal formation stage represents a major gap in our understanding of planet formation process. Because of this, the late-stage planet accretion models typically make arbitrary assumptions about planetesimals and pebbles distribution, while the state-of-the-art dust evolution models predict no or little planetesimal formation. With this contribution, I present a step toward bridging the gap between the early and late stages of planet formation by models that connect dust coagulation and planetesimal formation. With the aid of evaporation, outward diffusion, and re-condensation of water vapor, pile-up of large pebbles is formed outside of the snow line that facilitates planetesimal formation by streaming instability.

  20. The Role of Multiplicity in Disk Evolution and Planet Formation

    OpenAIRE

    Kraus, Adam L.; Ireland, Michael J.; Hillenbrand, Lynne A.; Martinache, Frantz

    2011-01-01

    The past decade has seen a revolution in our understanding of protoplanetary disk evolution and planet formation in single-star systems. However, the majority of solar-type stars form in binary systems, so the impact of binary companions on protoplanetary disks is an important element in our understanding of planet formation. We have compiled a combined multiplicity/disk census of Taurus-Auriga, plus a restricted sample of close binaries in other regions, in order to explore the role of multi...

  1. Language Games and Musical Understanding

    Directory of Open Access Journals (Sweden)

    Alessandro Arbo

    2013-05-01

    Full Text Available Wittgenstein has often explored language games that have to do with musical objects of different sizes (phrases, themes, formal sections or entire works. These games can refer to a technical language or to common parlance and correspond to different targets. One of these coincides with the intention to suggest a way of conceiving musical understanding. His model takes the form of the invitation to "hear (something as (something": typically, to hear a musical passage as an introduction or as a conclusion or in a certain tonality. However one may ask to what extent or in what terms (literal or metaphorical these procedures, and usually the intervention of language games, is requested by our common ways of understanding music. This article shows through the use of some examples that aspectual perception inherent to musical understanding does not require language games as a necessary condition (although in many cases the link between them seems very strong, in contradiction with the thesis of an essential linguistic character of music. At a basic level, it seems more appropriate to insist on the notion of a game: to understand music means to enter into the orbit of "music games" which show an autonomous functioning. Language games have, however, an important function when we develop this comprehension in the light of the criteria of judgment that substantiate the manner in which music is incorporated in and operates within specific forms of life.

  2. Understanding the land management paradigm

    DEFF Research Database (Denmark)

    Enemark, Stig

    2006-01-01

    There is a worldwide need to build understanding of the land management paradigm and for institutional development to establish sustainable national concepts. This includes creation and adoption of a policy on land development, and an approach that combines the land administration...

  3. Understanding FE Mergers. Research Report

    Science.gov (United States)

    Calvert, Natasha

    2009-01-01

    This report presents research findings and discussion to help develop an understanding of what gives rise to mergers and, when they do happen, what makes them work. The research has focused on merger activity between further education (FE) colleges since incorporation in 1993. Mergers are highly contextual, and part of ensuring success is…

  4. An Exercise in Artistic Understanding.

    Science.gov (United States)

    Mason, Rachel

    1982-01-01

    Describes an attempt to use two theories of literary criticism as a research strategy for interpreting art. Paul Ricoeur's interpretation theory and Northrup Frye's Anatomy of Criticism were adopted as approaches to the problem of understanding religious or mystical paintings by Norman Adams. (AM)

  5. Understanding Algorithms in Different Presentations

    Science.gov (United States)

    Csernoch, Mária; Biró, Piroska; Abari, Kálmán; Máth, János

    2015-01-01

    Within the framework of the Testing Algorithmic and Application Skills project we tested first year students of Informatics at the beginning of their tertiary education. We were focusing on the students' level of understanding in different programming environments. In the present paper we provide the results from the University of Debrecen, the…

  6. Young Children's Understanding of Denial

    Science.gov (United States)

    Austin, Keith; Theakston, Anna; Lieven, Elena; Tomasello, Michael

    2014-01-01

    Although a fair amount is known about young children's production of negation, little is known about their comprehension. Here, we focus on arguably the most complex basic form, denial, and how young children understand denial, when it is expressed in response to a question with gesture, single word, or sentence. One hundred twenty-six children in…

  7. Understanding neutrino masses and mixings

    Indian Academy of Sciences (India)

    atmospheric neutrino observations, where there is a deficit of observed neutrinos compared to theoretical expectations. ... and reactor neutrinos as in the Kamland experiment have also shown deficits in their flux compared to ... In this brief overview, I wish to draw attention to some of the theoretical ideas for understanding ...

  8. Spectroscopy, Understanding the Atom Series.

    Science.gov (United States)

    Hellman, Hal

    This booklet is one of the "Understanding the Atom" Series. The science of spectroscopy is presented by a number of topics dealing with (1) the uses of spectroscopy, (2) its origin and background, (3) the basic optical systems of spectroscopes, spectrometers, and spectrophotometers, (4) the characteristics of wave motion, (5) the…

  9. Explanation, understanding, and unrealistic models

    NARCIS (Netherlands)

    Hindriks, Frank

    How can false models be explanatory? And how can they help us to understand the way the world works? Sometimes scientists have little hope of building models that approximate the world they observe. Even in such cases, I argue, the models they build can have explanatory import. The basic idea is

  10. Intuitive Understanding of Base Rates

    DEFF Research Database (Denmark)

    Austin, Laurel

    Purpose: This study examines whether physicians and other adults intuitively understand that the probability a positive test result is a true positive (positive predictive value, PPV) depends on the base rate of disease in the population tested. In particular, this research seeks to examine...

  11. Understanding and Teaching Practical Wisdom

    Science.gov (United States)

    Bassett, Caroline L.

    2011-01-01

    Because wisdom is such a complex and multidimensional construct, it is difficult to study, much less to define. Based on the author's understanding, her definition of wisdom is as follows: "Wisdom is about human flourishing; it is having sufficient awareness in various situations and contexts to act in ways that enhance our common humanity." This…

  12. Do Children Understand Fraction Addition?

    Science.gov (United States)

    Braithwaite, David W.; Tian, Jing; Siegler, Robert S.

    2017-01-01

    Many children fail to master fraction arithmetic even after years of instruction. A recent theory of fraction arithmetic (Braithwaite, Pyke, & Siegler, in press) hypothesized that this poor learning of fraction arithmetic procedures reflects poor conceptual understanding of them. To test this hypothesis, we performed three experiments…

  13. Understanding and Supporting Window Switching

    NARCIS (Netherlands)

    Tak, S.

    2011-01-01

    Switching between windows on a computer is a frequent activity, but finding and switching to the target window can be inefficient. This thesis aims to better un-derstand and support window switching. It explores two issues: (1) the lack of knowledge of how people currently interact with and switch

  14. Understanding Mathematics: Some Key Factors

    Science.gov (United States)

    Ali, Asma Amanat; Reid, Norman

    2012-01-01

    Mathematics is well known as a subject area where there can be problems in terms of understanding as well as retaining positive attitudes. In a large study involving 813 school students (ages approximately 10-12) drawn from two different school systems in Pakistan, the effect of limited working memory capacity on performance in mathematics was…

  15. When Do Children Understand "Opposite"?

    Science.gov (United States)

    Phillips, Catherine I; Pexman, Penny M

    2015-08-01

    The aims of the present research were to determine (a) the age at which children with typical development understand the concept of opposite, (b) whether this is related to other cognitive abilities or experiences, and (c) whether there is early implicit understanding of the concept. Children (N = 204) between 3 and 5 years of age were randomly assigned to 1 of 3 experimental conditions in a novel opposite task. Children's language and working memory skills were assessed, and parents provided information about children's access to learning materials about opposites. In the opposite task, 4- and 5-year-olds, but not 3-year-olds, demonstrated acquisition of the concept of opposite. Children demonstrated this understanding only when asked for the "opposite" one, suggesting that antonymy was not made salient by stimulus properties alone. Children's accuracy was not significantly related to their language or working memory skills, to their child care experience, or to whether parents reported having books or games about opposites or playing opposite word games with children. Eye gaze analyses provided no evidence for early implicit understanding of the concept of opposite. Children with typical development have a concept of opposite by 4 years of age.

  16. Educators' Understanding of Workplace Bullying

    Science.gov (United States)

    de Wet, Corene

    2014-01-01

    This article looks at educators' understanding of workplace bullying through the lens of a two- dimensional model of bullying. Educators, who were furthering their studies at the University of the Free State, were invited to take part in a study on different types of bullying. Deductive, directed content analysis was used to analyse 59…

  17. Understanding and Counseling Transgender Clients

    Science.gov (United States)

    Kirk, James; Belovics, Robert

    2008-01-01

    Because transgender individuals experience widespread employment discrimination, counselors need to understand and be able to work with members of the gay, lesbian, bisexual, and transgender communities. The aim of this article is to help counselors become more transgender literate by (a) defining gender dysphoric disorder and related terms; (b)…

  18. Flexibility in embodied language understanding

    Directory of Open Access Journals (Sweden)

    Roel M Willems

    2011-06-01

    Full Text Available Do people use sensori-motor cortices to understand language? Here we review neurocognitive studies of language comprehension in healthy adults and evaluate their possible contributions to theories of language in the brain. We start by sketching the minimal predictions that an embodied theory of language understanding makes for empirical research, and then survey studies that have been offered as evidence for embodied semantic representations. We explore four debated issues: first, does activation of sensori-motor cortices during action language understanding imply that action semantics relies on mirror neurons? Second, what is the evidence that activity in sensori-motor cortices plays a functional role in understanding language? Third, to what extent do responses in perceptual and motor areas depend on the linguistic and extra-linguistic context? And finally, can embodied theories accommodate language about abstract concepts? Based on the available evidence, we conclude that sensori-motor cortices are activated during a variety of language comprehension tasks, for both concrete and abstract language. Yet, this activity depends on the context in which perception and action words are encountered. Although modality-specific cortical activity is not a sine qua non of language processing even for language about perception and action, sensori-motor regions of the brain appear to make functional contributions to the construction of meaning, and should therefore be incorporated into models of the neurocognitive architecture of language.

  19. Interpretive Hermeneutic Phenomenology: Clarifying Understanding ...

    African Journals Online (AJOL)

    The philosophical orientation of Gadamerian hermeneutic phenomenology is explored in this paper. Gadamer offers a hermeneutics of the humanities that differs significantly from models of the human sciences historically rooted in scientific methodologies. In particular, Gadamer proposes that understanding is first a mode ...

  20. Understanding Agency and Educating Character

    Science.gov (United States)

    Roth, Klas

    2011-01-01

    How can we understand human agency, and what does it mean to educate character? In this essay Klas Roth develops a Kantian notion, one that suggests we render ourselves efficacious and autonomous in education and elsewhere. This requires, among other things, that we are successful in bringing about the intended result through our actions and the…

  1. Filipino children's understanding of peace

    NARCIS (Netherlands)

    Oppenheimer, L.J.T.; Kuipers, I.

    2003-01-01

    This study reports on 10-year-old Filipino children's understanding of peace, war, and strategies to attain peace. In total, 56 children were presented with a semistructured interview consisting of free associations to peace and questions pertaining to the definitions of peace and war and strategies

  2. Expanding the Understanding of Evolution

    Science.gov (United States)

    Musante, Susan

    2011-01-01

    Originally designed for K-12 teachers, the Understanding Evolution (UE) Web site ("www.understandingevolution.org") is a one-stop shop for all of a teacher's evolution education needs, with lesson plans, teaching tips, lists of common evolution misconceptions, and much more. However, during the past five years, the UE project team learned that…

  3. Understanding the Problem of Pornography.

    Science.gov (United States)

    Metzger, Leigh Ann

    This report was written to clarify the terms often associated with pornography and to help readers understand the issue of pornography more clearly. The first chapter defines pornography, as it was defined by the United States Attorney General's Commission on Pornography, as "that material (which) is predominantly sexually explicit and intended…

  4. Formative cell divisions: principal determinants of plant morphogenesis.

    Science.gov (United States)

    Smolarkiewicz, Michalina; Dhonukshe, Pankaj

    2013-03-01

    Formative cell divisions utilizing precise rotations of cell division planes generate and spatially place asymmetric daughters to produce different cell layers. Therefore, by shaping tissues and organs, formative cell divisions dictate multicellular morphogenesis. In animal formative cell divisions, the orientation of the mitotic spindle and cell division planes relies on intrinsic and extrinsic cortical polarity cues. Plants lack known key players from animals, and cell division planes are determined prior to the mitotic spindle stage. Therefore, it appears that plants have evolved specialized mechanisms to execute formative cell divisions. Despite their profound influence on plant architecture, molecular players and cellular mechanisms regulating formative divisions in plants are not well understood. This is because formative cell divisions in plants have been difficult to track owing to their submerged positions and imprecise timings of occurrence. However, by identifying a spatiotemporally inducible cell division plane switch system applicable for advanced microscopy techniques, recent studies have begun to uncover molecular modules and mechanisms for formative cell divisions. The identified molecular modules comprise developmentally triggered transcriptional cascades feeding onto microtubule regulators that now allow dissection of the hierarchy of the events at better spatiotemporal resolutions. Here, we survey the current advances in understanding of formative cell divisions in plants in the context of embryogenesis, stem cell functionality and post-embryonic organ formation.

  5. Metastability in the formation of an experimental traffic jam

    Energy Technology Data Exchange (ETDEWEB)

    Nakayama, Akihiro [Faculty of Science and Technology, Meijo University, Nagoya 468-8502 (Japan); Fukui, Minoru [Nakanihon Automotive College, Sakahogi 505-0077 (Japan); Kikuchi, Macoto [Cybermedia Center, Osaka University, Toyonaka 560-0043 (Japan); Hasebe, Katsuya [Aichi University, Miyoshi 470-0296 (Japan); Nishinari, Katsuhiro [Department of Aeronautics and Astronautics, University of Tokyo, Bunkyo 113-8656 (Japan); Sugiyama, Yuki [Department of Complex Systems Science, Nagoya University, Nagoya 464-8601 (Japan); Tadaki, Shin-ichi [Computer and Network Center, Saga University, Saga 840-8502 (Japan); Yukawa, Satoshi [Department of Earth and Space Science, Osaka University, Toyonaka 560-0043 (Japan)], E-mail: spock@ccmfs.meijo-u.ac.jp

    2009-08-15

    We show detailed data about the process of jam formation in a traffic experiment on a circuit without any bottlenecks. The experiment was carried out using a circular road on a flat ground. At the initial stage, vehicles are running homogeneously distributed on the circuit with the same velocity, but roughly 10 min later a traffic jam emerges spontaneously on the circuit. In the process of the jam formation, we found a homogeneous flow with large velocity is temporarily realized before a jam cluster appears. The instability of such a homogeneous flow is the key to understanding jam formation.

  6. Metastability in the formation of an experimental traffic jam

    Science.gov (United States)

    Nakayama, Akihiro; Fukui, Minoru; Kikuchi, Macoto; Hasebe, Katsuya; Nishinari, Katsuhiro; Sugiyama, Yuki; Tadaki, Shin-ichi; Yukawa, Satoshi

    2009-08-01

    We show detailed data about the process of jam formation in a traffic experiment on a circuit without any bottlenecks. The experiment was carried out using a circular road on a flat ground. At the initial stage, vehicles are running homogeneously distributed on the circuit with the same velocity, but roughly 10 min later a traffic jam emerges spontaneously on the circuit. In the process of the jam formation, we found a homogeneous flow with large velocity is temporarily realized before a jam cluster appears. The instability of such a homogeneous flow is the key to understanding jam formation.

  7. Influence of Streptococcus mutans on Enterococcus faecalis biofilm formation.

    Science.gov (United States)

    Deng, Dong Mei; Hoogenkamp, Michel A; Exterkate, Rob A M; Jiang, Lei Meng; van der Sluis, Lucas W M; Ten Cate, Jacob M; Crielaard, Wim

    2009-09-01

    An important virulence factor of Enterococcus faecalis is its ability to form biofilms. Most studies on biofilm formation have been carried out by using E. faecalis monocultures. Given the polymicrobial nature of root canal infections, it is important to understand biofilm formation of E. faecalis in the presence of other microorganisms. Eight clinical strains of E. faecalis were tested for biofilm formation on hydroxyapatite disks in the presence and absence of a Streptococcus mutans biofilm. Significantly more E. faecalis viable cells were found in biofilms in the presence of S. mutans. This phenomenon was, however, strain-dependent. Of the 8 strains tested, biofilm formation of strains AA-OR34, ER5/1, and V583 was not influenced by S. mutans biofilms. The results from this study, especially the strain difference, underline the importance of studying biofilm formation in a more realistic multispecies setting.

  8. Galaxy Formation and Evolution

    CERN Document Server

    Spinrad, Hyron

    2005-01-01

    The evolution in the form and structure of galaxies which has taken place since the universe was in its infancy is one of the most closely studied by astrophysicists and cosmologists today. It has profound implications for our understanding of how the universe itself has evolved over the past 12 billion years or so. This book will discuss the evolution of galaxies in detail, emphasising the boundaries of our knowledge about the most distant galaxies, but demonstrating how it is possible to make important comparisons between nearby galaxies and the most distant current observed. The author will also review galaxy morphology and its likely (but as yet unproven) history.

  9. The idiopathic interstitial pneumonias: understanding key radiological features

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, S. [Department of Radiology, Churchill Hospital, Old Road, Oxford OX3 7LJ (United Kingdom); Benamore, R., E-mail: Rachel.Benamore@orh.nhs.u [Department of Radiology, Churchill Hospital, Old Road, Oxford OX3 7LJ (United Kingdom)

    2010-10-15

    Many radiologists find it challenging to distinguish between the different interstitial idiopathic pneumonias (IIPs). The British Thoracic Society guidelines on interstitial lung disease (2008) recommend the formation of multidisciplinary meetings, with diagnoses made by combined radiological, pathological, and clinical findings. This review focuses on understanding typical and atypical radiological features on high-resolution computed tomography between the different IIPs, to help the radiologist determine when a confident diagnosis can be made and how to deal with uncertainty.

  10. Food Composition Database Format and Structure: A User Focused Approach.

    Science.gov (United States)

    Clancy, Annabel K; Woods, Kaitlyn; McMahon, Anne; Probst, Yasmine

    2015-01-01

    This study aimed to investigate the needs of Australian food composition database user's regarding database format and relate this to the format of databases available globally. Three semi structured synchronous online focus groups (M = 3, F = 11) and n = 6 female key informant interviews were recorded. Beliefs surrounding the use, training, understanding, benefits and limitations of food composition data and databases were explored. Verbatim transcriptions underwent preliminary coding followed by thematic analysis with NVivo qualitative analysis software to extract the final themes. Schematic analysis was applied to the final themes related to database format. Desktop analysis also examined the format of six key globally available databases. 24 dominant themes were established, of which five related to format; database use, food classification, framework, accessibility and availability, and data derivation. Desktop analysis revealed that food classification systems varied considerably between databases. Microsoft Excel was a common file format used in all databases, and available software varied between countries. User's also recognised that food composition databases format should ideally be designed specifically for the intended use, have a user-friendly food classification system, incorporate accurate data with clear explanation of data derivation and feature user input. However, such databases are limited by data availability and resources. Further exploration of data sharing options should be considered. Furthermore, user's understanding of food composition data and databases limitations is inherent to the correct application of non-specific databases. Therefore, further exploration of user FCDB training should also be considered.

  11. Food Composition Database Format and Structure: A User Focused Approach

    Science.gov (United States)

    Clancy, Annabel K.; Woods, Kaitlyn; McMahon, Anne; Probst, Yasmine

    2015-01-01

    This study aimed to investigate the needs of Australian food composition database user’s regarding database format and relate this to the format of databases available globally. Three semi structured synchronous online focus groups (M = 3, F = 11) and n = 6 female key informant interviews were recorded. Beliefs surrounding the use, training, understanding, benefits and limitations of food composition data and databases were explored. Verbatim transcriptions underwent preliminary coding followed by thematic analysis with NVivo qualitative analysis software to extract the final themes. Schematic analysis was applied to the final themes related to database format. Desktop analysis also examined the format of six key globally available databases. 24 dominant themes were established, of which five related to format; database use, food classification, framework, accessibility and availability, and data derivation. Desktop analysis revealed that food classification systems varied considerably between databases. Microsoft Excel was a common file format used in all databases, and available software varied between countries. User’s also recognised that food composition databases format should ideally be designed specifically for the intended use, have a user-friendly food classification system, incorporate accurate data with clear explanation of data derivation and feature user input. However, such databases are limited by data availability and resources. Further exploration of data sharing options should be considered. Furthermore, user’s understanding of food composition data and databases limitations is inherent to the correct application of non-specific databases. Therefore, further exploration of user FCDB training should also be considered. PMID:26554836

  12. ASDF - A Modern Data Format for Seismology

    Science.gov (United States)

    Krischer, Lion; Smith, James; Lei, Wenjie; Lefebvre, Matthieu; Ruan, Youyi; Sales de Andrade, Elliot; Podhorszki, Norbert; Bozdag, Ebru; Tromp, Jeroen

    2017-04-01

    Seismology as a science is driven by observing and understanding data and it is thus vital to make this as easy and accessible as possible. The growing volume of freely available data coupled with ever expanding computational power enables scientists to take on new and bigger problems. This evolution is to some part hindered as existing data formats have not been designed with it in mind. We present ASDF (http://seismic-data.org), the Adaptable Seismic Data Format, a novel, modern, and especially practical data format for all branches of seismology with particular focus on how it is incorporated into seismic full waveform inversion workflows. The format aims to solve five key issues: Efficiency: Fast I/O operations especially in high performance computing environments, especially limiting the total number of files. Data organization: Different types of data are needed for a variety of tasks. This results in ad hoc data organization and formats that are hard to maintain, integrate, reproduce, and exchange. Data exchange: We want to exchange complex and complete data sets. Reproducibility: Oftentimes just not existing but crucial to advance our science. Mining, visualization, and understanding of data: As data volumes grow, more complex, new techniques to query and visualize large datasets are needed. ASDF tackles these by defining a structure on top of HDF5 reusing as many existing standards (QuakeML, StationXML, PROV) as possible. An essential trait of ASDF is that it empowers the construction of completely self-describing data sets including waveform, station, and event data together with non-waveform data and a provenance description of everything. This for example for the first time enables the proper archival and exchange of processed or synthetic waveforms. To aid community adoption we developed mature tools in Python as well as in C and Fortran. Additionally we provide a formal definition of the format, a validation tool, and integration into widely used

  13. IMPACTS OF BIOFILM FORMATION ON CELLULOSE FERMENTATION

    Energy Technology Data Exchange (ETDEWEB)

    Leschine, Susan

    2009-10-31

    This project addressed four major areas of investigation: i) characterization of formation of Cellulomonas uda biofilms on cellulose; ii) characterization of Clostridium phytofermentans biofilm development; colonization of cellulose and its regulation; iii) characterization of Thermobifida fusca biofilm development; colonization of cellulose and its regulation; and iii) description of the architecture of mature C. uda, C. phytofermentans, and T. fusca biofilms. This research is aimed at advancing understanding of biofilm formation and other complex processes involved in the degradation of the abundant cellulosic biomass, and the biology of the microbes involved. Information obtained from these studies is invaluable in the development of practical applications, such as the single-step bioconversion of cellulose-containing residues to fuels and other bioproducts. Our results have clearly shown that cellulose-decomposing microbes rapidly colonize cellulose and form complex structures typical of biofilms. Furthermore, our observations suggest that, as cells multiply on nutritive surfaces during biofilms formation, dramatic cell morphological changes occur. We speculated that morphological changes, which involve a transition from rod-shaped cells to more rounded forms, might be more apparent in a filamentous microbe. In order to test this hypothesis, we included in our research a study of biofilm formation by T. fusca, a thermophilic cellulolytic actinomycete commonly found in compost. The cellulase system of T. fusca has been extensively detailed through the work of David Wilson and colleagues at Cornell, and also, genome sequence of a T. fusca strain has been determine by the DOE Joint Genome Institute. Thus, T. fusca is an excellent subject for studies of biofilm development and its potential impacts on cellulose degradation. We also completed a study of the chitinase system of C. uda. This work provided essential background information for understanding how C. uda

  14. Deposition of boron on fuel rod surface under sub-cooled boiling conditions-An approach toward understanding AOA occurrence

    International Nuclear Information System (INIS)

    Uchida, Shunsuke; Asakura, Yamato; Suzuki, Hiroaki

    2011-01-01

    Highlights: → AOA is one of key issues for maintaining stable PWR operation. → AOA is caused by boron accumulation on fuel rods under sub-cooled boiling. → Unstable depositing boron was seldom measured on fuel rods. → MED model was originally developed for crud deposition on boiling surface. → Amount of boron on fuel rod can be evaluated with MED model. - Abstract: In PWR primary coolant, it has been assumed that Li and B ions deposited on fuel rod surface under sub-cooled boiling conditions and they changed their chemical forms by chemical reaction with nickel iron oxides on the fuel surface. Accumulated boron on the fuel led to axial offset anomaly (AOA). In the present paper, the amount of boron deposited on the fuel surface was evaluated from two directions. The first calculated the amount with the extended micro-layer evaporation and dry-out (MED) model and the other estimated it from the viewpoint of reactor reactivity (neutron economy calculation). The MED model, which was developed for predicting iron crud deposition on the boiling surface of BWR fuel rods, was extended for application to metallic ion deposition, and modified to evaluate deposition of crud and metallic ions on sub-cooled boiling surface. Processes of growth and collapse of bubbles were calculated to determine the time from bubble generation to collapse and total evaporation volume and deposition amount of boron and metallic ions and their oxides on the fuel rod surface for a bubble. Finally chemical reaction rates of boron and metallic ions were calculated in the deposits. From the evaluation, it was concluded that: (i) the calculated deposition amount of boron on the fuel rod surface, which was four or forty times larger than measured amounts of boron and nickel oxides compounds, was seldom measured in the fuel deposits due to its high release rate; (ii) its hideout return during the reactor shutdown period was seldom observed due to its high concentration in the primary coolant

  15. Formation and evolution of exoplanets in different environments

    OpenAIRE

    Adibekyan, Vardan

    2017-01-01

    The ultimate goal of exoplanetologists is to discover life outside our Earth and to fully understand our place in the Universe. Even though we have never been closer to attaining this goal, we still need to understand how and where the planets (efficiently) form. In this manuscript I briefly discuss the important role of stellar metallicity and chemistry on the formation and evolution of exoplanets.

  16. Understanding Polymer-Cell Attachment.

    Science.gov (United States)

    Venturato, Andrea; MacFarlane, Gillian; Geng, Jin; Bradley, Mark

    2016-12-01

    The development of polymeric materials with cell adhesion abilities requires an understanding of cell-surface interactions which vary with cell type. To investigate the correlation between cell attachment and the nature of the polymer, a series of random and block copolymers composed of 2-(dimethylamino)ethyl acrylate and ethyl acrylate are synthesized through single electron transfer living radical polymerization. The polymers are synthesized with highly defined and controlled monomer compositions and exhibited narrow polydispersity indices. These polymers are examined for their performance in the attachment and growth of HeLa and HEK cells, with attachment successfully modeled on monomer composition and polymer chain length, with both cell lines found to preferentially attach to moderately hydrophobic functional materials. The understanding of the biological-material interactions assessed in this study will underpin further investigations of engineered polymer scaffolds with predictable cell binding performance. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Socialization, Language, and Scenic Understanding

    DEFF Research Database (Denmark)

    Olesen, Henning Salling; Weber, Kirsten

    2013-01-01

    is based on a transformation of the "scenic understanding" from a clinical to a text interpretation, which seeks to understand collective unconscious meaning in text, and is presented with an illustration of the interpretation procedure from social research. Then follows a brief systematic account of key......»Sozialisation, Sprache und szenisches Verstehen. Alfred Lorenzers Beitrag zu einer psychosozialen Methodologie«. The article is a guided tour to Alfred Lorenzer's proposal for an "in-depth hermeneutic" cultural analysis methodology which was launched in an environment with an almost complete split...... between social sciences and psychology/psychoanalysis. It presents the background in his materialist socialization theory, which combines a social reinterpretation of the core insights in classical psychoanalysis – the unconscious, the drives – with a theory of language acquisition. His methodology...

  18. Understanding Tattoos in Medicolegal Assessments.

    Science.gov (United States)

    Klein, Carolina A; Kenedi, Christopher

    2018-03-01

    Tattoos have held different meanings throughout history, with particular significance in cultural, social, and clinical contexts. Psychiatrists have long been interested in understanding the relevance of the tattooed body in a clinical or forensic evaluation and in settling on interpretive models that hold reliable value. Some studies have indicated that tattoos may be associated with markers of high-risk behaviors, mental illness diagnosis, and personality disorders. We attempt to provide an updated and comprehensive guide for forensic evaluators, so they can incorporate the observation of tattoos into their assessments with a review of the scientific literature that supports the interpretations and places them in context. The association between tattoos and risk, mental health, or behavioral implications is not as clear or linear as one might initially imagine, and mental health professionals should have a sophisticated understanding of the practice. © 2018 American Academy of Psychiatry and the Law.

  19. KNOWLEDGE UNDERSTANDING AND ADVANCED SEARCHING

    Directory of Open Access Journals (Sweden)

    R Vidya

    2017-04-01

    Full Text Available It’s a comprehensive fact that millions of people around the world surf the Internet for want of answers for their questions. Generally, the questions are asked in the form of Searching or direct questions which follow perfect ontological directions. It is important that the system understands the questions in the right sense and can provide the best answer for all the questions raised in the web forum. One such pragmatic method is required which is expected to provide optimum solution to achieve best answers for questions that not only percepts language but also follows perfect ontological information in accordance with the cyber law. This Proposed Model presents a new dynamic model called Knowledge Understanding and Advance Searching (KUAS that studies the importance of Smart Question Answering with other question answering engines like START and proves to give the optimal solution compared to them.

  20. Understanding peace a comprehensive introduction

    CERN Document Server

    Fox, Michael Allen

    2013-01-01

    Understanding Peace: A Comprehensive Introduction fills the need for an original, contemporary examination of peace that is challenging, informative, and empowering. This well-researched, fully documented, and highly accessible textbook moves beyond fixation on war to highlight the human capacity for nonviolent cooperation in everyday life and in conflict situations. After deconstructing numerous ideas about war and explaining its heavy costs to humans, animals, and the environment, discussion turns to evidence for the existence of peaceful societies. Further topics include the role of nonviolence in history, the nature of violence and aggression, and the theory and practice of nonviolence. The book offers two new moral arguments against war, and concludes by defining peace carefully from different angles and then describing conditions for creating a culture of peace. Understanding Peace brings a fresh philosophical perspective to discussions of peace, and also addresses down-to-earth issues about effecting ...

  1. RPC understanding and future perspectives

    CERN Document Server

    Santonico, R

    2004-01-01

    The understanding of the long-term behavior of the RPCs developed as dedicated muon trigger detectors at LHC and presently in construction, is analyzed. The main aging mechanisms are reviewed. The gas contamination by the hydrofluoric acid is analyzed as a possible aging cause and a method for measuring the fluorine concentration in the exhaust gas is described. Finally, the use of RPCs for the detection of Cosmic Ray Extensive Air Showers and their imaging capabilities are briefly discussed.

  2. Educators' understanding of workplace bullying

    OpenAIRE

    Corene de Wet

    2014-01-01

    This article looks at educators' understanding of workplace bullying through the lens o a two-dimensional model of bullying. Educators, who were furthering their studies at the University of the Free State, were invited to take part in a study on different types of bullying. Deductive, directed content analysis was used to analyse 59 participants' descriptions of workplace bullying. The study found that the theoretical model provided a valuable framework for studying bullying in this context....

  3. Public understanding of sustainable tourism

    OpenAIRE

    Miller, G; Rathouse, K; Scarles, C; Holmes, K; Tribe, J

    2010-01-01

    If tourism is to become part of a more sustainable lifestyle, changes are needed to the patterns of behaviour adopted by the public. This paper presents the results of research conducted amongst members of the public in England on their understanding of sustainable tourism; their response to four desired tourism behaviour goals, and expectations about the role of government and the tourism industry in encouraging sustainable tourism. The research shows a lack of awareness of tourism’s impact ...

  4. Understanding the 'historical' electricity tariffs

    International Nuclear Information System (INIS)

    2010-01-01

    At the time of the debates about the French 'NOME' (new organization of the electricity market) law, it is interesting to analyse the principles which have led to elaborate the 'historical' electricity tariffs in France, in order to better understand the stakes around their recasting. Today, there exists 2 categories of tariffs: the regulated selling prices and the market offers. The regulated selling prices are different depending on the client (individuals, small professionals, companies)

  5. Understanding Intellectual Disability through Rasopathies

    OpenAIRE

    Alvaro, San Martín; Rafael, Pagani Mario

    2014-01-01

    Intellectual disability, commonly known as mental retardation in the International Classification of Disease from World Health Organization, is the term that describes an intellectual and adaptive cognitive disability that begins in early life during the developmental period. Currently the term intellectual disability is the preferred one. Although our understanding of the physiological basis of learning and learning disability is poor, a general idea is that such condition is quite permanent...

  6. Understanding service-oriented software.

    OpenAIRE

    Gold, N. E.; Knight, C.; Mohan, A.; Munro, M.

    2004-01-01

    Service-oriented software is being hailed as the next revolutionary approach to software development. Service orientation allows organizations to rapidly and dynamically form new software applications to meet changing business needs, thus alleviating the software evolution problems that occur with traditional applications. The largest of these problems is the need to understand existing software before changing it. This article looks ahead toward the automated construction of service-oriented...

  7. Understanding Intellectual Disability through Rasopathies

    Science.gov (United States)

    Alvaro, San Martín; Rafael, Pagani Mario

    2014-01-01

    Intellectual disability, commonly known as mental retardation in the International Classification of Disease from World Health Organization, is the term that describes an intellectual and adaptive cognitive disability that begins in early life during the developmental period. Currently the term intellectual disability is the preferred one. Although our understanding of the physiological basis of learning and learning disability is poor, a general idea is that such condition is quite permanent. However, investigations in animal models suggest that learning disability can be functional in nature and as such reversible through pharmacology or appropriate learning paradigms. A fraction of the cases of intellectual disability is caused by point mutations or deletions in genes that encode for proteins of the RAS/MAP Kinase signaling pathway known as RASopathies. Here we examined the current understanding of the molecular mechanisms involved in this group of genetic disorders focusing in studies which provide evidence that intellectual disability is potentially treatable and curable. The evidence presented supports the idea that with the appropriate understanding of the molecular mechanisms involved, intellectual disability could be treated pharmacologically and perhaps through specific mechanistic-based teaching strategies. PMID:24859216

  8. Formation feedback control of UAV flight

    Science.gov (United States)

    Stegall, Stephen

    This thesis is a study of formation control with autonomous unmanned aerial vehicles using the formation as feedback. There is also an investigation of formation methods presenting insight into different algorithms for formations. A rigid formation is achieved using a proportional-derivative virtual structure with a formation feedback controller. There is an emphasis on stick controlled aerodynamics. The rigid formation is verified by a simulation of a longitudinal model. Formation control ideas are presented for rigid formations.

  9. Understanding value formation : A study of marketing communications practices at the food retailer ICA

    OpenAIRE

    Ots, Mart

    2010-01-01

    ICA AB is Sweden’s largest retail and wholesale firm, a cooperation of retail proprietors. Here it is studied as the nation’s largest media firm. It is the largest advertiser, the largest publisher of consumer magazines, and plausibly the most advanced user of household shopping data for marketing purposes. ICA’s marketing media system is operated by a constellation of different professional groups, and the study at hand asks questions about how practitioners in different professional communi...

  10. Understanding image contrast formation in TiO.sub.2./sub. with force spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Yurtsever, A.; Fernandez-Torre, D.; González, C.; Jelínek, Pavel; Pou, P.; Sugimoto, Y.; Abe, M.; Pérez, R.; Morita, S.

    2012-01-01

    Roč. 85, č. 12 (2012), "125416-1"-"125416-9" ISSN 1098-0121 R&D Projects: GA MŠk(CZ) ME10076 Institutional research plan: CEZ:AV0Z10100521 Keywords : DFT * AFM * force spectroscopy * atomic resolution Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.767, year: 2012

  11. Natural formation and degradation of chloroacetic acids and volatile organochlorines in forest soil: challenges to understanding

    OpenAIRE

    Laturnus, Frank; Fahimi, Isabelle; Gryndler, Milan; Hartmann, Anton; Heal, Mathew R; Matucha, Miroslav; Schoeler, Heinfried; Schroll, Reiner; Svensson, Teresia

    2005-01-01

    Goal, Scope and Background. The anthropogenic environmental emissions of chloroacetic acids and volatile organochlorines have been under scrutiny in recent years because the two compound groups are suspected to contribute to forest dieback and stratospheric ozone destruction, respectively. The two organochlorine groups are linked because the atmospheric photochemical oxidation of some volatile organochlorine compounds is one source of phytotoxic chloroacetic acids in the environment. Moreover...

  12. Nuclear structure effects in quasifission – understanding the formation of the heaviest elements

    Directory of Open Access Journals (Sweden)

    Hinde D. J.

    2016-01-01

    Full Text Available Quasifission is an important process suppressing the fusion of two heavy nuclei in reactions used to create superheavy elements. Quasifission results in rapid separation of the dinuclear system initially formed at contact. Achieving reliable a priori prediction of quasifission probabilities is a very diffcult problem. Through measurements with projectiles from C to Ni, the Australian National University’s Heavy Ion Accelerator Facility and CUBE spectrometer have been used to map out mass-angle distributions (MAD - the fission mass-ratio as a function of centre-of-mass angle. These provide information on quasifission dynamics in the least modeldependent way. Average quasifission time-scales have been extracted, and compared with TDHF calculations of the collisions, with good agreement being found. With the baseline information from the survey of experimental MAD, strong influences of the nuclear structure of the projectile and target nuclei can be clearly determined.

  13. Understanding and Mitigating Scale Formation on Membranes Used for Membrane Distillation of Wastewater During Space Travel

    Data.gov (United States)

    National Aeronautics and Space Administration — Water sustains life, and on space missions this resource is a vital commodity that must be safeguarded. For short-term missions it is most reliable and...

  14. Understanding the formation process of exceptionally long fullerene-based nanowires

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Geng, Junfeng; Solov'yov, Andrey V.

    2009-01-01

    In a recent study J. Geng, W. Zhou, P. Skelton, W. Yue, I. Kinloch, A.Windle, and B. Johnson, J. Am. Chem. Soc. 130, 2527 (2008)., it was demonstrated that exceptionally long fullerene nanowires, with a length-to-width aspect ratio as large as $3000-5000, can be grown from 1,2,4-trimethylbenzene ...

  15. Insights into Students' Conceptual Understanding Using Textual Analysis: A Case Study in Signal Processing

    Science.gov (United States)

    Goncher, Andrea M.; Jayalath, Dhammika; Boles, Wageeh

    2016-01-01

    Concept inventory tests are one method to evaluate conceptual understanding and identify possible misconceptions. The multiple-choice question format, offering a choice between a correct selection and common misconceptions, can provide an assessment of students' conceptual understanding in various dimensions. Misconceptions of some engineering…

  16. Students' Understanding of Acid, Base and Salt Reactions in Qualitative Analysis.

    Science.gov (United States)

    Tan, Kim-Chwee Daniel; Goh, Ngoh-Khang; Chia, Lian-Sai; Treagust, David F.

    2003-01-01

    Uses a two-tier, multiple-choice diagnostic instrument to determine (n=915) grade 10 students' understanding of the acid, base, and salt reactions involved in basic qualitative analysis. Reports that many students did not understand the formation of precipitates and the complex salts, acid/salt-base reactions, and thermal decomposition involved in…

  17. Large Format Radiographic Imaging

    International Nuclear Information System (INIS)

    Rohrer, J. S.; Stewart, Lacey; Wilke, M. D.; King, N. S.; Baker A, S.; Lewis, Wilfred

    1999-01-01

    Radiographic imaging continues to be a key diagnostic in many areas at Los Alamos National Laboratory (LANL). Radiographic recording systems have taken on many form, from high repetition-rate, gated systems to film recording and storage phosphors. Some systems are designed for synchronization to an accelerator while others may be single shot or may record a frame sequence in a dynamic radiography experiment. While film recording remains a reliable standby in the radiographic community, there is growing interest in investigating electronic recording for many applications. The advantages of real time access to remote data acquisition are highly attractive. Cooled CCD camera systems are capable of providing greater sensitivity with improved signal-to-noise ratio. This paper begins with a review of performance characteristics of the Bechtel Nevada large format imaging system, a gated system capable of viewing scintillators up to 300 mm in diameter. We then examine configuration alternatives in lens coupled and fiber optically coupled electro-optical recording systems. Areas of investigation include tradeoffs between fiber optic and lens coupling, methods of image magnification, and spectral matching from scintillator to CCD camera. Key performance features discussed include field of view, resolution, sensitivity, dynamic range, and system noise characteristics

  18. Continuing galactic formation

    International Nuclear Information System (INIS)

    McCanney, J.M.

    1981-01-01

    A new theory for galactic arm formation shows the arms to be continually eminating from the galactic nucleus due to a continual influx of cosmic dust. In the neighborhood of the nucleus the problem is treated as a fluid flow and a simple solution is given using conservation of momentum. When rotational dynamics are included the spinning arm system is the result. This solution resolves the problem of the missing mass, accounts for warped disk galaxies and gives a probable source for the gravity waves measured by Weber which eminate from our galactic center. Reversal of arm direction is demonstrated and examples of such reversals are cited. An approximate theoretical estimate of the age of our Sun is found to be in good agreement with radio isotope dating. A general result shows why twin star systems are in such great abundance in a galaxy. It gives a model of galactic evolution which begins with only a single massive nucleus with the collapsing gas clouds forming the arms. (orig.)

  19. Relational (Trans)formations

    DEFF Research Database (Denmark)

    Soelmark, Nathalie Wind

    2015-01-01

    their generative immediacy structure understandings of body, technology and kinship. Biotechnological and media technological intersections are widely acknowledged within kinship studies and media studies as ways in which biotechnology networks itself into the way we think of the body socially, economically...... to the relevance of considering how the aesthetic-affective dimension of media cultural productions have ramifications for how we relate to ourselves, others, and the world where the small, mundane, ambivalent, and ugly feelings play a crucial role. Article 2 “Atmospheric Video Blogs on Infertility” relates...... in Technostorks (2006) and The Baby Clinic (2012)” takes departure in discussions and critiques within kinship studies of intersections between media and ART, particular media’s role in the public face of IVF as miraculous and spectacular (Franklin 2013; Bouquet 2002). Through an analysis of a Danish TV...

  20. Understanding complex interactions using social network analysis.

    Science.gov (United States)

    Pow, Janette; Gayen, Kaberi; Elliott, Lawrie; Raeside, Robert

    2012-10-01

    The aim of this paper is to raise the awareness of social network analysis as a method to facilitate research in nursing research. The application of social network analysis in assessing network properties has allowed greater insight to be gained in many areas including sociology, politics, business organisation and health care. However, the use of social networks in nursing has not received sufficient attention. Review of literature and illustration of the application of the method of social network analysis using research examples. First, the value of social networks will be discussed. Then by using illustrative examples, the value of social network analysis to nursing will be demonstrated. The method of social network analysis is found to give greater insights into social situations involving interactions between individuals and has particular application to the study of interactions between nurses and between nurses and patients and other actors. Social networks are systems in which people interact. Two quantitative techniques help our understanding of these networks. The first is visualisation of the network. The second is centrality. Individuals with high centrality are key communicators in a network. Applying social network analysis to nursing provides a simple method that helps gain an understanding of human interaction and how this might influence various health outcomes. It allows influential individuals (actors) to be identified. Their influence on the formation of social norms and communication can determine the extent to which new interventions or ways of thinking are accepted by a group. Thus, working with key individuals in a network could be critical to the success and sustainability of an intervention. Social network analysis can also help to assess the effectiveness of such interventions for the recipient and the service provider. © 2012 Blackwell Publishing Ltd.