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Sample records for understand crud formation

  1. Electrokinetic and electrochemical corrosion studies related to crud formation

    International Nuclear Information System (INIS)

    Scenini, Fabio; Palumbo, Gaetano; Stevens, Nicholas; Cook, Tony; Banks, Andrew

    2012-09-01

    A potentially important mechanism for the flow-induced deposition of CRUD from pressurised high temperature primary water is the effect of 'streaming potentials' that develop across the electrochemical double layer of a metallic surface as a result of fluid flow across a pressure gradient or orifice. Thus, under such conditions, streaming currents develop normal to a surface and may result in preferential oxidation, for example of dissolved ferrous to ferric ions with their subsequent deposition as an oxide. The approach presented in this paper was to consider the electrokinetic problem is to firstly consider the magnitude of currents that can be developed under a given set of flow/mass transport conditions and, secondly, to consider the way in which these relatively small currents might give rise to oxide deposition. Electrochemical measurements on 304L samples were carried out over a range of temperatures in hydrogenated, alkaline water. The test conditions were chosen in order to simulate PWR primary water conditions. Furthermore, in order to facilitate the electrochemical studies, the ferrous ion concentration in the solution was also enhanced by the presence of a mild steel plate left in the autoclave to corrode. By employing the cyclic voltammetry technique interpreted using the Randles-Sevcik equation it was possible to calculate the concentration of ferrous ions and their diffusion coefficient. A miniature flow cell was designed for the purpose of creating regions of accelerated flow with consequent formation of anodic and cathodic regions so as to be able to measure the streaming currents. A study was carried out in order to better understand the potential which is associated with the streaming potential as function of the velocity and temperature at fixed pH. (authors)

  2. 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)

  3. 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.)

  4. 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.

  5. 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)

  6. Report to the DOE on the ''Crud II'' project

    International Nuclear Information System (INIS)

    Dawn Elizabeth Janney; Douglas L. Porter; O. Keener Earle; Joshua L. Peterson; Rick Demmer; Jeffrey J. Giglio; Mark W. Huntley; Michael G. Jones

    2006-01-01

    This report documents SEM, TEM, and chemical analyses from crud samples from a commercially operating reactor. Crud (radioactive corrosion products forming in operating reactors) is a major problem for the electric power industry. Conditions leading to its formation are complex and poorly understood, and it is widely recognized that accurate materials characterization of crud is essential to understanding how to prevent it or reduce the operating and health hazards it creates. However, crud samples are difficult to collect and analyze because of their high radioactivity and common formation on activated fuel pins. This report documents analyses of crud samples from a commercial boiling water reactor that were provided by the Electric Power Research Institute to Idaho National Laboratory (INL) as part of an on-going effort to develop the capabilities of INL to address problems associated with currently operating commercial reactors. The samples represent material collected during two refueling outages. Each sample was analyzed by gamma scanning, atomic absorption spectroscopy, and inductively coupled plasma mass spectroscopy in the Analytical Laboratory at INL. Seven of the samples were also analyzed using optical microscopy in the Electron Microscopy Laboratory at INL. Two of the samples were further analyzed using transmission and scanning electron microscopy and electron diffraction at INL. Although not comprehensive, the electron-microscopy analyses are among the few published examples of similar work in the last several decades

  7. Study on the Simulation of Crud Formation using Piping Materials of Nuclear Power Plant in High Temperature Water

    International Nuclear Information System (INIS)

    Kim, Sang Hyun; Kim, In Sup; Lee, Kun Jai

    2005-01-01

    High temperature - high pressure apparatus was developed to simulate nickel fewite corrosion products which were main compositions of the radioactive crud in the nuclear power plant. Corrosion product similar to the crud was obtained by a tube accumulator system. Nickel alloy (Inconel 690) and carbon steel (SA106 Gr. C) were corroded at 270 in the corrosion product generator. Ni ions and Fe ions dissolved by corrosion reaction were able to be transported to the accumulator because the crud generation mechanism was the solubility change with temperature. To evaluate the properties of simulated corrosion products, scanning electron microscope (SEM) observation and EDAX analysis were performed. SEM observation of corrosion product showed the needle like or crystal structure of oxide depending on precipitating location. The crystal oxide was the nickel ferrite, which was similar to the crud in nuclear power plants.

  8. Development and application of high performance resins for crud removal

    International Nuclear Information System (INIS)

    Deguchi, Tatsuya; Izumi, Takeshi; Hagiwara, Masahiro

    1998-01-01

    The development of crud removal technology has started with the finding of the resin aging effect that an old ion exchange resin, aged by long year of use in the condensate demineralizer, had an enhanced crud removal capability. It was confirmed that some physical properties such as specific surface area and water retention capacity were increased due to degradation caused by long year of contact with active oxygens in the condensate water. So, it was speculated that those degradation in the resin matrix enhanced the adsorption of crud particulate onto the resin surface, hence the crud removal capability. Based on this, crud removal resin with greater surface area was first developed. This resin has shown an excellent crud removal efficiency in an actual power plant, and the crud iron concentration in the condensate effluent was drastically reduced by this application. However, the cross-linkage of the cation resin had to be lowered in a delicate manner for that specific purpose, and this has caused higher organic leachables from the resin, and the sulfate level in the reactor was raised accordingly. Our major goals, therefore, has been to develop a crud resin of as little organic leachables as possible with keeping the original crud removal efficiency. It was revealed through the evaluation of the first generation crud resin and its improved version installed in the actual condensate demineralizers that there was a good correlation between crud removal efficiency and organic leaching rate. The bast one among a number of developmental resins has shown the organic leaching rate of 1/10 of that of the original crud resin (ETR-C), and the crud removal efficiency of 90%. So far as we understand, the resin was considered to have the best overall balance between crud removal and leaching characteristics. The result of six month evaluation of this developmental resin, ETR-C3, in one vessel of condensate demineralizer of a power plant will be presented. (J.P.N.)

  9. Characteristics of fuel CRUD from Ringhals Unit 4. A comparison of CRUD samples from ultrasonic fuel cleaning and fuel scrape

    International Nuclear Information System (INIS)

    Chen, Jiaxin; Eskhult, Jonas; Marks, Chuck; Dingee, John; Bengtsson, Bernt; Wells, Daniel

    2014-01-01

    The characteristics and behaviour of PWR fuel CRUD are closely related to plant radiation field build-up and the risks of CRUD-Induced Power Shifts (CIPS, previously AOA) and CRUD-Induced Localized Corrosion (CILC). At Ringhals NPP fuel scrape technology has frequently been used to collect fuel CRUD samples as a part of plant water chemistry monitoring programs. In 2012, high efficiency ultrasonic fuel cleaning (HE-UFC) technology was first used at Ringhals Unit 4 to reduce the risk of CIPS, which was expected to increase due to steam generator replacement and a subsequent power uprate. In the HE-UFC system a “first-of-a-kind” CRUD sampling system was installed for collecting fuel CRUD. It is of interest to compare the fuel CRUD samples collected by the two different CRUD sampling methods and to understand if HE-UFC crud sampling could be used to replace or supplement the fuel scrape method. This paper presents some preliminary results on isotopic compositions, elemental compositions, and phase compositions of fuel CRUD samples collected from similar fuel rods and assemblies by both methods during the 2012 refueling outage, one cycle after steam generator replacement at Ringhals Unit 4. The results show that the characteristics of fuel CRUD sampled by HE-UFC and fuel scrape, although not always identical, were similar or correlated to some extent in terms of weight ratios of Ni to Fe and Cr to Fe as well as specific activities of Co-58, Co-60 and Cr-51. However, due to the limited experience with the HE-UFC sampling method, more consideration is required if the statistical significance of the obtained data and indications are to be verified. (author)

  10. 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

  11. Iron crud supply device to reactor coolant

    International Nuclear Information System (INIS)

    Baba, Takao.

    1993-01-01

    In a device for supplying iron cruds into reactor coolants in a BWR type power plant, a system in which feed water containing iron cruds is supplied to the reactor coolants after once passing through an ion exchange resin is disposed. As a result, iron cruds having characteristics similar with those of naturally occurring iron cruds in the plant are obtained and they react with ionic radioactivity, to form composite oxides. Then, iron cruds having high performance of being secured to the surface of a fuel cladding tube can be supplied to the reactor coolants, thereby enabling to greatly reduce the density of reactor water ionic radioactivity. In its turn, dose rate on the surface of pipelines can be reduced, thereby enabling to reduce operators' radiation exposure dose in the plant. Further, contamination of a condensate desalting device due to iron cruds can be prevented, and further, the density of the iron cruds supplied can easily be controlled. (N.H.)

  12. Crud deposition on fuel in WWER reactors

    International Nuclear Information System (INIS)

    Kysela, J.; Svarc, V.; Androva, K.; Ruzickova, M.

    2008-01-01

    Reliability of nuclear fuel and radiation fields surrounding primary systems are important aspects of overall nuclear reactor safety. Corrosion product (crud) deposition on fuel surfaces has implications for fuel performance through heat transfer and local chemistry modifications. Crud is currently one of the key industry issues and has been implicated in several recent cases of crud-related fuel failures and core plugging. Activated crud is deposited on out-of-core surfaces, mainly steam generators, resulting in high radiation fields and high doses of plant staff. Due to radiation build-up in primary circuit systems, decontamination of primary systems components and steam generators is used. Several issues involving decontamination were observed in some cases. After decontamination higher corrosion product release occurs followed by subsequent crud deposition on fuel surfaces. The paper summarizes experience with water chemistry and decontamination that can influence crud deposition on fuel surfaces. The following areas are discussed: 1) Experience with crud deposition, primary water chemistry and decontamination under operating conditions; 2) The behaviour of organic compounds in primary coolant and on fuel surfaces; 3) A proposed experimental programme to study crud deposition. (authors)

  13. 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

  14. Understanding Alliance Formation Patterns

    Science.gov (United States)

    2015-12-01

    military, transportation, and communications technologies, which caused every place in the world to be politically significant. Second, “divisions of power...test a similar claim about the association between distance and dyadic alliance formation. In their first model, in which they use the complete data...1885 to 1990] are positively related to dyadic trade levels, and that their non- defense-pact counterparts are not significantly related to trade in

  15. Crud deposition modeling on BWR fuel rods

    International Nuclear Information System (INIS)

    Kucuk, Aylin; Cheng, Bo; Potts, Gerald A.; Shiralkar, Bharat; Morgan, Dave; Epperson, Kenny; Gose, Garry

    2014-01-01

    Deposition of boiling water reactor (BWR) system corrosion products (crud) on operating fuel rods has resulted in performance-limiting conditions in a number of plants. The operational impact of performance-limiting conditions involving crud deposition can be detrimental to a BWR operator, resulting in unplanned or increased frequency of fuel inspections, fuel failure and associated radiological consequences, operational restrictions including core power derate and/or forced shutdowns to remove failed fuel, premature discharge of individual bundles or entire reloads, and/or undesirable core design restrictions. To facilitate improved management of crud-related fuel performance risks, EPRI has developed the CORAL (Crud DepOsition Risk Assessment ModeL) tool. This paper presents a summary of the CORAL elements and benchmarking results. Applications of CORAL as a tool for fuel performance risk assessment are also discussed. (author)

  16. Results from the first cycle of the PWR crud deposition test (IFA-665.1)

    International Nuclear Information System (INIS)

    Bennett, Peter

    2004-03-01

    The main objective of IFA-665.1 is to deposit crud on fuel rods operating under PWR thermal-hydraulic and water chemistry conditions, and to measure the resulting power reduction due to incorporation of boron into the crud. The test has operated for 160 days at power. Water chemistry conditions were 3.15 ppm LiOH and 1400 ppm boron (pH 300 =7.0). The coolant inlet temperature was 290/294 C, with sub-cooled nucleate boiling along the upper half of the fuel bundle. This report presents the results from the first cycle of operation. Three methods have been used to attempt to accelerate crud formation: (i) injection of simulated crud particles (NiFe 2 O 4 ); (ii) pH transients (reduction of pH 300 from 7.0 to 6.0 for periods of 48 hours); and (iii) oxygen addition transients. While the pH transients resulted in movement of large amounts of corrosion products around the loop, no significant deposition onto the fuel surfaces was measured. Comparison of the heat fluxes in IFA-665 with those in previous tests in which crud deposition has occurred does not clearly identify reasons for the lack of crud formation, although it is noted that higher heat fluxes may be required. In addition, the relatively benign boiling conditions in the current test (small void fraction with no detached voidage) may partly explain the absence of crud formation. For the second cycle of the test, changes will be made to the water chemistry to attempt to increase the concentrations of dissolved and colloidal Fe and Ni in the test rig, such that a continuous (Fe + Ni) level of 100 ppb will be targeted, with short-term concentrations of colloids of up to 500 ppb. (Author)

  17. A Study of CRUD Deposition Processing and Composition Materials

    International Nuclear Information System (INIS)

    Jung, Yanghong; Kim, H. M.; Yoo, B. O.; Baik, S. J.; Ahn, S. B.

    2013-07-01

    After cutting and drilling the spent fuel, we made a scrapping crud from the surface on the cladding. To scrap crud on the cladding surface, we made a special apparatus which has a 1/1,000 mm accuracy, but we could not taken crud. Thus, we effort the most possible use equipment to take crud samples, but unfortunately failed to get crud. We assume the crud would be dissolved. Because of the two fuel cladding, 17ACE7 and Plus 7, which were storage in PIEF pool for few years, it would be chemical reaction between pool water and crud deposited on the cladding. But we could not know the reason clearly. Therefore, it was impossible to analysis the crud, after that this project had to be stopped

  18. 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)

  19. Effect of surface oxidation of ZIRLO fuel cladding tube on crud deposition

    International Nuclear Information System (INIS)

    Park, Moon Sic; Baek, Seung Heon; Shim, Hee-Sang; Kim, Jung Gu; Hur, Do Haeng

    2016-01-01

    Crud has often led a lot of problems in the primary coolant system such as fuel cladding corrosion, power distortion and reduction, and radio-activity build-up of out-of-core [2-3]. Although a crud-induced localized corrosion (CILC) is a severe accident, in which fuel is leaked into the coolant, it is rarely happened but a crud-induced power shift (CIPS) has frequently occurred in worldwide PWR plants. CIPS, or power axial offset anomaly (AOA) has long been realized in the nuclear industry since early 1970s. In late 1980s, severe AOA phenomena were found in Callaway plants in U. S. and later in many power plants around the world. The axial offset (AO) is defined by the power distortion between the top half of the core and the bottom half of the core. When the plant exceeds acceptable limit of 3% in AO value, it is judged as AOA occurrence and this is forced to reduce power or shutdown. AOA is caused by a hideout for large accumulation of boron into porous crud and its formation is accelerated by increased sub-cooled nucleate boiling (SNB) with sufficient corrosion product supply. Crud has often led a lot of problems in the primary coolant system such as fuel cladding corrosion, power distortion and reduction, and radio-activity build-up of out-of-core. Although a crud-induced localized corrosion (CILC) is a severe accident, in which fuel is leaked into the coolant, it is rarely happened but a crud-induced power shift (CIPS) has frequently occurred in worldwide PWR plants. CIPS, or power axial offset anomaly (AOA) has long been realized in the nuclear industry since early 1970s. In late 1980s, severe AOA phenomena were found in Callaway plants in U. S. and later in many power plants around the world. The axial offset (AO) is defined by the power distortion between the top half of the core and the bottom half of the core. When the plant exceeds acceptable limit of 3% in AO value, it is judged as AOA occurrence and this is forced to reduce power or shutdown. AOA is

  20. 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.

  1. The status of AOA and the CRUD deposition in Korean PWR

    International Nuclear Information System (INIS)

    Maeng, Wan Young; Choi, Byung Seon; Min, Duck Kee; Kwon, Hyung Moon; Choi, In Kyu; Yeon, Je Won; Kim, Jae Ik; Woo, Hae Seuk; Kim, Young Koo; Park, Jong Youl

    2009-01-01

    Korean nuclear power plants have experienced several times of AOA (Axial Offset Anomaly). AOA in Korean plants seems to be the consequence of high burn-up and long term cycle of the nuclear fuel as experienced in the foreign plants. The root cause of AOA is not clearly understood until now. Even though plants which have similar operation condition (similar thermo-hydraulic condition, water chemistry and structural materials), the AOA behavior of each plant is different from other plants. To have an understanding of the plant specific behavior of each plant and to have the countermeasures to AOA, the mechanism of CRUD deposition should be clarified. The purpose of this study is to investigate the AOA status and the CRUD characteristics in Korean power utilities. We surveyed the current AOA occurrence history and collected the Korean CRUD data which are scattered in various sources. To have some understanding on the key variables of AOA, we built experimental apparatus for CRUD deposition in simulated PWR environment. The status and the investigation plans of our experimental study are introduced in the paper

  2. 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)

  3. Field Demonstration of Fuel Crud Filtration System at Ulchin Plant

    International Nuclear Information System (INIS)

    Kang, Duk-Won; Lee, Doo-Ho; Park, Jong-Youl; Choi, In-Kyu

    2007-01-01

    Crud deposited onto the fuel assemblies in nuclear power plants was not a serious problem until an upper core flux depression named Axial Offset Anomaly (AOA) was found at Callaway, USA in 1989. Though the mechanism of an AOA is not completely understood, crud is believed to be a key component of initiating AOA. After the sufficient amount of corrosion products in the reactor cooling system are deposited on the fuel clad by a sub-cooled nucleate boiling, boron is adsorbed in the crud. Thus a measurable reduction in the neutron flux occurs which causes an AOA problem. A filtration system has been developed to remove the fuel crud from irradiated fuel assemblies for mitigating the axial offset anomaly under a technical cooperation agreement with DEI (Dominion Engineering Inc.). This filtration system with a fuel cleaning fixture was successfully demonstrated at Ulchin plant unit 2. Within several minutes, detachable crud deposits were effectively removed from the clad surfaces of the fuel assembly. Also, to characterize the crud particles for each fuel assembly, a small crud sampling device and radiation monitor devices were connected to the filtration system during the cleaning operation. In this study, we completed a functional test and demonstration of an ultrasonic fuel cleaning system by using four spent fuel assemblies. It took only 5 minutes to remove the fuel crud from each fuel assembly. In addition, collective dose rates indicated an average of 8 R/Hr per assembly

  4. 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

  5. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Joe, Justin H. [BNF Consulting (United States); Kim, Seung Jun, E-mail: skim@lanl.gov [Mechanical and Thermal Engineering Group (AET-1), Los Alamos National Laboratory (United States); Jones, Barclay G. [Department of Nuclear Plasma Radiological Engineering, University of Illinois Urbana-Champaign (United States)

    2016-04-15

    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{sub 2}, O{sub 2}, and H{sub 2}O{sub 2}) can be directly related to corrosion issues on fuel cladding. - Abstract: This research examines the concentration of radiolysis species (H{sub 2}, O{sub 2}, and H{sub 2}O{sub 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{sub 2}, O{sub 2}, and H{sub 2}O{sub 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.

  7. 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.

  8. Control of Crud and Boron Deposition for AOA Prevention

    International Nuclear Information System (INIS)

    Maeng, W. Y.; Choi, B. S.; Na, J. W.

    2010-07-01

    Ο Understand effects of water chemistry variables on AOA and investigate AOA mechanism Ο Mitigate AOA in terms of water chemistry control AOA(Axial Offset Anomaly) has been reported in many PWR plants in the world, including Korea, especially in the plants of higher burn-up and longer cycle operation or power up-rate. A test loop has been designed and made by KAERI, in order to investigate and mitigate AOA problems in Korea. This project included the study of hydrodynamic simulation and the modeling about AOA. The analysis of radioactive crud was performed to investigate of NPPs primary water chemical effect on AOA and to reduce the radioactive dose rate. The present primary water chemistry guideline of EPRI is to operate NPPs with AOA in the condition of initial 3.5 ppm Li and pH 7.1. However, the tests in this project indicate that the amount of deposit on fuel cladding can be reduced when an appropriate water chemistry strategy is applied. High pH water chemistry in the beginning of operation is recommended based on the results of this project

  9. 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.

  10. Estimate of the crud contribution to shipping cask containment requirements

    International Nuclear Information System (INIS)

    Sandoval, R.P.; Einziger, R.E.; Jordan, H.; Malinauskas, A.P.; Mings, W.J.

    1992-01-01

    This paper reports that a methodology is developed to relate U.S. Code of Federal Regulations, Title 10, Part 71 (10CFR71) containment requirements to leak rates for the special case in which the only radioactive species having a potential for escape form the cask is that associated with debris (crud) contained on the fuel assemblies being transported. The methodology accounts for the characteristics of the crud and for attenuation of the gas-borne crud particulates once they become suspended within the cask. Calculations are performed for typical spent-fuel transport cask geometries and the normal and accident conditions prescribed in 10CFR71. The most current published data are used for crud composition and structure, specific activity, spallation mechanics and fractions, and crud particle size. The containment criteria leak rates are calculated assuming 5-yr-old spent fuel. In each accident case, the containment leak rate criteria are well in excess of 10 cm 3 /s. Under normal conditions of transport, the regulatory containment requirements are met by leak rates ranging from 1.5 x 10 -3 cm 3 /s to 1.5 x 10 -4 cm 3 /s for the transport of boiling water reactor fuel assemblies and form 1.8 x 10 -2 cm 3 /s to 1.3 x 10 -3 cm 3 /s for pressurized water reactor fuel assemblies. The calculated leak rates are most sensitive to the cask design, type of fuel, and particle size distribution. Conservatism of the limiting leak rates is discussed

  11. Method of eliminating cruds in the primary coolants of reactors

    International Nuclear Information System (INIS)

    Tamura, Takaaki.

    1984-01-01

    Purpose: To eliminate cruds in the primary coolants by using rind of onions or peanuts. Method: Since cruds contained in the reactor primary coolants increase the radioactive exposure to reactor operators, they have been intended to remove by ion exchange resins. In this invention, rind of onions or peanuts are crushed into an adequate particle size and packed into an absorption column instead of ion exchange resins into which primary coolants are circulated. The powderous onions or peanuts rind contain glucoside such as cosmosiin and has an effect of cationic exchanger, they satisfactorily catch heavy metals such as Fe and Cu. They have an excellent filtering effect even under a high pH condition and are excellent in economical point of view. They can be decrease the volume of the absorption column, reduce their devolume after use through corrosion and easily subjected to waste procession through oxidizing combustion in liquid. (Nakamoto, H.)

  12. Crud separation from equipment drain of BWR atomic power station

    International Nuclear Information System (INIS)

    Hayashi, Masaru; Yamaguchi, Hisashi; Moriya, Yasuhiro; Koshiba, Yukihiko; Ota, Yoshiharu.

    1977-01-01

    In the primary cooling systems of BWR nuclear power stations, radioactive crud is generated and accumulates in reactors and circulating systems, which causes the radiation exposure of workers at the time of the inspection and maintenance of reactors. The chemical composition and grain size distribution of crud differ largely according to the construction of primary systems, the operational conditions of reactors, and the process of operation. The study on the application of nuclear pore membrane filter NPMF to the separation of crud in the waste water from equipment drain systems has been carried out. With the NPMF, clarified filtrate can be obtained without any filter aid, therefore the secondary waste of filter sludge is not generated. When the filter is clogged, the filtration capability can be regenerated by reverse flow washing, and continuous filtration is possible actually because the regeneration takes only short time. The NPMF is the polycarbonate membrane of about 10 μm thick, to which charged particles are irradiated vertically, and the flight tracks are etched with alkali solution, thus the required pore treatment is applied. The basic investigation of waste liquid, the endurance test of actual filters, the filtration test with the pilot apparatus, the demonstration test with an actual equipment, and the design of the actual equipment have been carried out for three years. (Kako, I.)

  13. Out-of-pile test of the crud separator system. (I)

    International Nuclear Information System (INIS)

    Takasaki, Akito; Iimura, Katsumichi; Tanaka, Isao

    1991-01-01

    The JMTR Project has been developing the crud separator system since 1981, and the advanced system has been fabricated for the in-pile test to be performed in the HBWR (Norway). The crud separator system removes magnetized crud circulating in a primary circuit by the permanent magnet assembly surrounded inside and outside of the separator vessel. Before the in-pile test, out-of-pile test was carried out in the JMTR Project under the condition of atmospheric pressure and room temperature, and the simplified theoretical analysis for crud separation mechanism was also carried out. The out-of-pile test results suggested that separation factor increased with increasing magnetic susceptibility of crud and crud particle diameter, and decreased with increasing flow rate. These results were in good agreement with the theoretical analysis. The test results also showed that the crud size enlarger was effective in lower separation factor region, which related to lower magnetic susceptibility of crud, smaller crud diameter and higher flow rate. (author)

  14. 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

  15. 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.)

  16. 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.

  17. Understanding coupling between bone resorption and formation

    DEFF Research Database (Denmark)

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

    2013-01-01

    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...... histomorphometry and IHC on human iliac biopsy specimens, and showed that reversal cells are immunoreactive for factors typically expressed by osteoblasts, but not for monocytic markers. Furthermore, a subpopulation of reversal cells showed several distinctive characteristics suggestive of an arrested...

  18. 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

  19. 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

  20. 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)

  1. Potential impacts of crud deposits on fuel rod behaviour on high powered PWR fuel rods

    International Nuclear Information System (INIS)

    Wilson, W.; Comstock, R.J.

    1999-01-01

    Fuel assemblies operating with significant sub-cooled boiling are subject to deposition of surface deposits commonly referred to as crud. This crud can potentially cause concentration of chemical species within the deposits which can be detrimental to cladding performance in PWRs. In addition, these deposits on the surface of the cladding can result in power anomalies and erroneous reporting of fuel rod oxide thickness which can substantially hamper corrosion and core performance modeling efforts. Data is presented which illustrates the importance of accounting for the presence of crud on fuel cladding surfaces. Several methods used to correct for this phenomenon when collecting and analyzing zirconium alloy field oxide thickness measurements are described. Various observations related to crud characteristics and its impact on fuel rod performance are also addressed. (author)

  2. Preliminary Study on Effect of the Crud Deposits during LBLOCA Condition

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Byung Gil; Lee, Joo Suk; Bang, Young Seok; Oh, Deog Yeon; Woo, Sweng Woong [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2008-10-15

    The severe crud deposits on fuel rod could result in the increment of the fuel temperature during the operation of nuclear power plants. The crud inhibits heat transfer, causing the cladding temperature to increase due to the low thermal conductivity. In the event of LBLOCA at the NPP operated with heavy crud layers, the peak cladding temperature (PCT) will be higher than it would be if the cladding were clean. Therefore, NRC has been reviewing a petition for rule making to set the limit of crud and/or oxide thickness. Also, it requires that LOCA analysis be calculated by factoring the role of crud. Since the crud deposits caused the stored energy in the fuel to increase, it could influence the following requirement: The Initial Stored Energy in the Fuel in Appendix K to Part 50. ECCS Evaluation Models, to require that the steady-state temperature distribution and stored energy in the fuel at the onset of a postulated LOCA. Also, safety review guidelines in NUREG-0800.

  3. 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)

  4. Understanding Combustion and Soot Formation in Diesel Engines

    Science.gov (United States)

    2016-09-09

    distributions of PLII signals help understand the soot distributions within diesel/ biodiesel flames. In addition, planar laser-induced Figure 1. Transported ...Prescribed by ANSI Std. Z39.18 Page 1 of 1FORM SF 298 9/14/2016https://livelink.ebs.afrl.af.mil/livelink/llisapi.dll This project investigated biodiesel ...emissions testing. 1 FINAL REPORT Project title: Understanding combustion and soot formation in biodiesel fuelled diesel engines Lead Institute and

  5. 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

  6. Effects of Hydrodynamic Cavitation of a Restriction Orifice on Crud-like Deposits

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-10-15

    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 has 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 fundamentally

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

    International Nuclear Information System (INIS)

    Kim, Seong Man; Lee, Seung Won; Park, Seong Dae; Kang, Sa Rah; Seo, Han; Bang, In Cheol

    2012-01-01

    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

  8. Effects of Hydrodynamic Cavitation of a Restriction Orifice on Crud-like Deposits

    International Nuclear Information System (INIS)

    Kim, Seong Man; Lee, Seung Won; Park, Sung Dae; Kang, Sarah; Seo, Han; Bang, In Cheol

    2011-01-01

    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 has 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 fundamentally

  9. Crud removal with deep bed type condensate demineralizer in Tokai-2 BWR

    International Nuclear Information System (INIS)

    Abe, Ayumi; Takiguchi, Hideki; Numata, Kunio; Saito, Toshihiko

    1996-01-01

    The major objective and functions for the installation of the deep bed type condensate polishers in BWR power plants is to remove both ionic impurities caused by sea water leakage and suspended impurities called crud mainly consisting of metal oxides which are produced from metal corrosion. In considering the reduction of occupational radiation exposure level, it is extremely important to remove the crud effectively. In recent Japanese BWR power plants, condensate pre-filters with powdered ion exchange resins or with hollow fiber membrane have been installed to remove the crud at the upper stream of the deep bed polishers. In such plants, the crud removal is conventionally the secondary objective for the deep bed polishers. The Japan Atomic Power Company has introduced the small particle ion exchange resin and a soak regeneration method since April 1985, and then applied the low cross-linked resin since July 1995 at Tokai-2 Power Station, to improve the crud removal performance by using only deep bed type condensate demineralizer, and as a result condensate demineralizer outlet iron level has been kept below 1 ppb since 1991

  10. Crud removal by ion exchange resin DIAION HPAN10 and its mechanisms

    International Nuclear Information System (INIS)

    Tsuhara, Ryosuke; Goda, Takashi; Tokumaru, Izuru; Yano, Katsuhiko

    2014-01-01

    The metal corrosion products generated in the water systems of nuclear power plants (crud) should be efficiently removed from the water in order to maintain the safety and reliability of the plants' constituent materials and reduce radiation exposure to workers. Recently, we developed a new highly porous type of anion exchange resin product, 'DIAION HPAN10', which has a high crud removal capability. HPAN10 has a highly-developed porous structure, and it is considered that the structure contributes to the efficient capture of curd. Furthermore, HPAN10 was designed specially for the capture of crud, including physical properties such as proper macro pore size, particle size and strength. Therefore, the model crud removal capability of HPAN10 is ten times greater than that of conventional gel types. In regards to the mechanisms of curd removal by resin, it is generally considered that there are three factors which affect the capture of curd: they are filter effect, electric potential and curd penetration into resin particles by partially dissolution. On this report, new experimental data and the consideration about crud removal mechanisms are introduced. (author)

  11. 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

  12. Improved crud iron removal efficiency for powder resin type condensate filters

    International Nuclear Information System (INIS)

    Nagai, Hiroshi; Ino, Takao

    1989-01-01

    In 1984, a precoat type condensate filtration system was delivered to The Tokyo Electric Power Co., Inc. by Ebara and stable operation of the system is reported ever since. Originally, condensate filtration systems are used to remove crud iron in condensate water. However, it has become desirable to freely control the crud iron in the outlet flow of such filtration system. The main source of radioactivity in a BWR plant, is Cobalt 60, and it is necessary to optimally control the amount of crud iron released into the reactor to match the nickel and cobalt amounts in the reactor feed water for achieving an overall reduction of the concentration of radioactivity within the BWR plant. The method of such control, developed by the authors, is outlined in the following. By this method, the radioactive level within the overall plant is significantly decreased. Consequently, the risk of radioactive exposure of personnel at time of periodical checkup is greatly reduced. (author)

  13. Structural investigation of the spinel phase formed in fuel CRUD before and after zinc injection

    International Nuclear Information System (INIS)

    Chen, J.

    2002-01-01

    Spinel phase is an important constituent of fuel CRUD. Since it can accommodate 60 Co in its crystal structure, its stability in reactor water environment is crucial for the radioactivity control in LWR plants. With increasing curiosity about zinc injection technology, the mechanism of the interaction of zinc with the spinel has drawn much attention. This paper describes the crystal and microstructures of spinel phase in the fuel CRUD collected on four fuel rods of 1- and 5-cycle, respectively, from Barsebaeck 2 BWR before and after zinc injection operation. High precision X-ray powder diffraction technique has been applied to identify the phase compositions of fuel CRUD and to measure the cell length of the spinel phase formed. The results show that, after about 1-cycle zinc injection operation, the tenacious CRUD formed on the fresh fuel rod contains defective zinc oxide, in addition to hematite and spinel as commonly seen. Moreover, the phase ratio of spinel to hematite is much increased. The cell length of the spinel is increased accordingly, which is the direct evidence for the presence of zinc in the spinel structure. For the 5-cycle rod, however, neither zinc oxide nor any change in the phase ratio has been detected. The cell length of the spinel has been increased, in a less degree, however, as compared to that for the 1-cycle rod. The cell lengths of spinel are similar in both tenacious and loose CRUD layers, indicating that zinc was able to easily penetrate through the tenacious CRUD layer. (authors)

  14. 'Crud' detection and evaluation during the Embalse nuclear power plant's thermal cycle for powers of 100%

    International Nuclear Information System (INIS)

    Fernandez, A.; Rosales, A.H.; Mura, V.R.; Sentupery, C.; Rascon, H.

    1987-01-01

    This paper describes the 'crud' measurements performed during the Embalse nuclear power plant's thermal cycle for a power of 100% (645 MWe) under different purification conditions. The aim of this work is to optimize the four steam generators' tube plate cleaning in function of the sweeping produced by their purification. (Author)

  15. Optimization method to determine mass transfer variables in a PWR crud deposition risk assessment tool

    International Nuclear Information System (INIS)

    Do, Chuong; Hussey, Dennis; Wells, Daniel M.; Epperson, Kenny

    2016-01-01

    Optimization numerical method was implemented to determine several mass transfer coefficients in a crud-induced power shift risk assessment code. The approach was to utilize a multilevel strategy that targets different model parameters that first changes the major order variables, mass transfer inputs, then calibrates the minor order variables, crud source terms, according to available plant data. In this manner, the mass transfer inputs are effectively simplified as 'dependent' on the crud source terms. Two optimization studies were performed using DAKOTA, a design and analysis toolkit, with the difference between the runs, being the number of model runs using BOA, allowed for adjusting the crud source terms, therefore, reducing the uncertainty with calibration. The result of the first case showed that the current best estimated values for the mass transfer coefficients, which were derived from first principle analysis, can be considered an optimized set. When the run limit of BOA was increased for the second case, an improvement in the prediction was obtained with the results deviating slightly from the best estimated values. (author)

  16. Optimization of reactor coolant shutdown chemistry practices for crud inventory management

    International Nuclear Information System (INIS)

    Fellers, B.; Barnette, J.; Stevens, J.; Perkins, D.

    2002-01-01

    This report describes reactor coolant shutdown chemistry control practices at Comanche Peak Steam Electric Station (CPSES, TXU-Generation, USA). The shutdown evolution is managed from a process control perspective to achieve conditions most favorable to crud decomposition and to avoiding re-precipitation of metals. The report discusses the evolution of current industry practices and the necessity for greater emphasis on shutdown chemistry control in response to Axial Offset Anomaly and growth of ex-core radiation fields during outage conditions. Nuclear Industry experience with axial offset anomaly (AOA), radiation field growth and unexpected behavior of crud during reactor shutdowns has encouraged the refinement of chemistry control practices during plant shutdown and startup. The strong implication of nickel rich crud as a cause of AOA and unexpected crud behavior has resulted in a focus on nickel inventory management. The goals for Comanche Peak Steam Electric Station (CPSES) include maintaining solubility of metals and radioisotopes, maximizing nickel removal and effective cleanup with demineralizers. This paper provides results and lessons learned from long term efforts to optimize the shutdown process. (authors)

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

    International Nuclear Information System (INIS)

    Sawicki, J.A.; Dymarski, M.; Sawicka, B.D.

    1997-01-01

    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 2 O was sampled at reactor outlet headers and the deposits collected on 0.45 μm membrane filters were analyzed by using γ-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 μg/kg D 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 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 μg/kg D 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 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 ∼ 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 (∼ 5 to 30 wt. % Fe), apparently in the form of zirconium oxide. Zirconium oxide particles may originate largely from the wear of fuel bundle pads and pressure tube

  18. Crud treatment with 3 phase centrifuge in heap leach uranium process

    International Nuclear Information System (INIS)

    Hartmann, T.

    2010-01-01

    The presence of crud represents a permanent challenge for solvent extraction in the hydro-metal Uranium industry. The crud forms in the settlers of SX extraction. The crud is a stable emulsion which slowly spreads along the phase boundary between the aqueous and organic phase. Spreading of this intermediate phase is determined by the following influencing factors. Wind blows dust into the open settlers, some suspended solids coming with the pregnant leach solution (PLS) and wrong design of the mixers cause stable emulsions. Metallic solid residue is likewise responsible for the growth rate of the crud at the above-mentioned phase boundary. The crud can significantly impair the efficiency of hydro-metal extraction because the phase boundary between the aqueous and organic phases assumes substantial proportions, and the settlers cannot react flexibly. In a chain reaction, all settlers connected in series become infected with crud. The transfer of organic phase to the electrowinning (EW) cell can cause 'cathode burn'. The entrainment of electrolyte into the extraction stage can result in loss of pH control in the extraction circuit which will cause a drop in extraction efficiency. On the other hand, entrainment of the organic in the raffinate will result in organic losses to the leach circuit. Continuous treatment of the crud is extremely effective and reliable with a 3-phase separating solid bowl centrifuge. All three phases are separated distinctly from one another. All associated process steps exhibit a steady uniform efficiency. The main benefit for the customer is that process fluctuations in the extraction process will no longer occur. The 3-phase separating solid bowl centrifuge consists of an axial solid-wall bowl. The solid-wall bowl has a cylindrical section for simultaneous separation and clarification of the aqueous and organic liquid phase and a conical section for efficient solids dewatering. The 3-phase feed suspension is fed into the solid bowl

  19. What Do They Understand? Using Technology to Facilitate Formative Assessment

    Science.gov (United States)

    Mitten, Carolyn; Jacobbe, Tim; Jacobbe, Elizabeth

    2017-01-01

    Formative assessment is so important to inform teachers' planning. A discussion of the benefits of using technology to facilitate formative assessment explains how four primary school teachers adopted three different apps to make their formative assessment more meaningful and useful.

  20. 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

  1. Detection and replacement of crud accumulating fuel assemblies at the Loviisa-2 reactor

    International Nuclear Information System (INIS)

    Antila, M.

    1995-01-01

    At unit 2 of Loviisa NPP fuel bundle outlet temperatures had been increasing slowly from the beginning of November 1994 mainly at the six lead fuel bundles with new zirconium spacer grids (Z). The unit was taken to cold shut-down and started up again in January 1995. After a few days the increase of the outlet temperatures was confirmed to continue. It was decided to shut down the reactor again to examine and remove the new Z-bundles. One bundle was taken to closer investigations in the poolside inspection stand. The hexagonal shroud tube was removed and quite a lot of crud was detected on the lower surfaces of the spacer grids. All the six Z-bundles were removed and replaced by older bundles with steel spacers. A small reshuffling was performed to control the radial power distribution. The cause for the partial flow blockage causing the increasing temperatures was accumulation of crud particularly on the Zr-spacers. The root cause of the accumulation of crud has not yet been definitely cleared. It seems evident that it is related to the decontamination of the primary circuit performed last August. The extensive incore temperature measurement instrumentation and reactor core monitoring system had a central role in the early detection of the anomaly. Thus core thermal margins were not violated and possible fuel failures could be avoided. (orig.) (3 refs., 5 figs.)

  2. 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...

  3. Observations of crud deposits, corrosion and erosion of BWR and PWR fuel

    International Nuclear Information System (INIS)

    Bairiot, H.

    1983-01-01

    The BWR experience is limited to one reactor but the PWR experience covers a wide range of successive generations of power plants (7 in total). The systems are described and their water chemistry briefly commented. Some R and D performed on the effects of the operating regimes (steady state and transients) are summarized. Observations made by pool-side inspections and postirradiation examinations of fuel are outlined concerning water chemistry effects (crud deposits and corrosion) and ''mechanical'' coolant-cladding interaction (chip deposits and baffle jetting). (author)

  4. Formative Feedback in a Business School: Understanding the Student Perspective

    Science.gov (United States)

    Poppitt, Nicola J.; Iqbal, Yasser

    2009-01-01

    Inspired by a desire to improve the student experience, this paper reviews primary research carried out into the use of formative feedback within a Business School at a "new" university in the UK. The research adopted a qualitative approach with key objectives to gain staff and student perspectives on the role and practice of feedback…

  5. Satisfaction Formation Processes in Library Users: Understanding Multisource Effects

    Science.gov (United States)

    Shi, Xi; Holahan, Patricia J.; Jurkat, M. Peter

    2004-01-01

    This study explores whether disconfirmation theory can explain satisfaction formation processes in library users. Both library users' needs and expectations are investigated as disconfirmation standards. Overall library user satisfaction is predicted to be a function of two independent sources--satisfaction with the information product received…

  6. 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

  7. Hydrodynamic cavitation characteristics of an orifice system and its effects on CRUD-like SiC deposition

    International Nuclear Information System (INIS)

    Kim, Seong Man; Bang, In Cheol

    2016-01-01

    Highlights: • CRUD-like SiC deposition was prepared for examining the erosion test in the cavitation field. • We investigated the comparison between swirl flow and common flow on cavitation. • Magnitude of shock pressure was investigated at low cavitation number. - Abstract: In a nuclear power plant, chalk river unidentified deposit (CRUD) is known as a deposit that is composed of corrosion and oxidation materials. It has a porous structure, which combines with boron that is injected into the coolant for controlling power levels. The buildup of corrosion products on the fuel cladding surface has proven to be particularly significant for both BWRs and PWRs. The high temperature of the cladding surface attracts impurities and chemical additives in the reactor coolant that deposit on the fuel rod surface in a process. The deposits on a fuel rod, known as CRUD, can be tenacious, insulative compounds capable of increasing the local clad temperature and accelerating clad corrosion—sometimes to the point of fuel failure. The deposition of CRUD on fuel cladding surfaces causes uneven heating of the reactor core. The situation is exacerbated by boron, which is added to the coolant to control power levels. However, boron becomes concentrated and is deposited within thick CRUD deposits. Ultrasonic mechanisms were developed but they have limitations for decontamination. In this experiment, a decontamination test was conducted using a sample sheet that was composed of SiC/water nanofluids. In addition, it was exposed to swirl flow and common flow for checking enhanced cavitation. It is measured by a pressure film, as shock pressure is associated with cavitation number. As a pressure film is wetted easily in water, it was injected into a holder. In the experiment, the maximum shock pressure was obtained during swirl flow at a low cavitation number. This indicates that pressure was concentrated on the pressure film. Consequently, cavitation can get rid of CRUD layers

  8. 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

  9. 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)

  10. The Effect of Computer Models as Formative Assessment on Student Understanding of the Nature of Models

    Science.gov (United States)

    Park, Mihwa; Liu, Xiufeng; Smith, Erica; Waight, Noemi

    2017-01-01

    This study reports the effect of computer models as formative assessment on high school students' understanding of the nature of models. Nine high school teachers integrated computer models and associated formative assessments into their yearlong high school chemistry course. A pre-test and post-test of students' understanding of the nature of…

  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. 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

  13. 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.

  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. 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.

  16. Understanding the Sun-Earth Libration Point Orbit Formation Flying Challenges For WFIRST and Starshade

    Science.gov (United States)

    Webster, Cassandra M.; Folta, David C.

    2017-01-01

    In order to fly an occulter in formation with a telescope at the Sun-Earth L2 (SEL2) Libration Point, one must have a detailed understanding of the dy-namics that govern the restricted three body system. For initial purposes, a linear approximation is satisfactory, but operations will require a high-fidelity modeling tool along with strategic targeting methods in order to be successful. This paper focuses on the challenging dynamics of the transfer trajectories to achieve the relative positioning of two spacecraft to fly in formation at SEL2, in our case, the Wide-Field Infrared Survey Telescope (WFIRST) and a proposed Starshade. By modeling the formation transfers using a high fidelity tool, an accurate V approximation can be made to as-sist with the development of the subsystem design required for a WFIRST and Starshade formation flight mission.

  17. 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.

  18. Understanding the geographic distribution of tropical cyclone formation for applications in climate models

    Science.gov (United States)

    Tory, Kevin J.; Ye, H.; Dare, R. A.

    2018-04-01

    Projections of Tropical cyclone (TC) formation under future climate scenarios are dependent on climate model simulations. However, many models produce unrealistic geographical distributions of TC formation, especially in the north and south Atlantic and eastern south Pacific TC basins. In order to improve confidence in projections it is important to understand the reasons behind these model errors. However, considerable effort is required to analyse the many models used in projection studies. To address this problem, a novel diagnostic is developed that provides compelling insight into why TCs form where they do, using a few summary diagrams. The diagnostic is developed after identifying a relationship between seasonal climatologies of atmospheric variables in 34 years of ECMWF reanalysis data, and TC detection distributions in the same data. Geographic boundaries of TC formation are constructed from four threshold quantities. TCs form where Emanuel's Maximum Potential Intensity, V_{{PI}}, exceeds 40 {ms}^{{ - 1}}, 700 hPa relative humidity, RH_{{700}}, exceeds 40%, and the magnitude of the difference in vector winds between 850 and 200 hPa, V_{{sh}}, is less than 20 {ms}^{{ - 1}}. The equatorial boundary is best defined by a composite quantity containing the ratio of absolute vorticity (η ) to the meridional gradient of absolute vorticity (β ^{*}), rather than η alone. {β ^*} is also identified as a potentially important ingredient for TC genesis indices. A comparison of detected Tropical Depression (TD) and Tropical Storm (TS) climatologies revealed TDs more readily intensify further to TS where {V_{PI}} is elevated and {V_{sh}} is relatively weak. The distributions of each threshold quantity identify the factors that favour and suppress TC formation throughout the tropics in the real world. This information can be used to understand why TC formation is poorly represented in some climate models, and shows potential for understanding anomalous TC formation

  19. Hide out return test and blowndown crud composition under ETA chemistry

    International Nuclear Information System (INIS)

    Chocron, Mauricio; Rodriguez, Ivanna; Saucedo, Ramona; Rodriguez-Aliciardi, Matias; Montes, Juan

    2012-09-01

    Among the techniques recommended for the surveillance of the Steam Generators (SGs) are (i) the follow-up of the corrosion products in the Feed Water and Blown down water and the corresponding accumulation mass balance and (ii) The follow-up of ionic impurities normally present in the main condensate and feed water that can enter the cycle either by condenser leakages or even by the make-up water. This is so, no matter how well the the cycle is constructed or the make-up water plant behaves given the continuous phase change present in it and the subsequent concentration. A synergistic effect exists between both, corrosion products and impurities, (i) and (ii), because impurities concentrate in the deposits creating a potentially risky environment for the steam generator tubes. Hide out return determination consists in the measurement of the concentration of ions, anions and cations, present in the blown-down water which are eluted during the shutdown along with the reduction of power and temperature. The integrated value provides figures to perform several evaluations like: (i) how well the make-up water plant has performed during the cycle, (ii) presence of condenser in leakages, (iii) amount of deposits present in the steam generator and (iv) it allows to estimate the chemistry in operation inside the steam generator liquid phase inside the sludge pile. Embalse, a CANDU 6 pressurized heavy water reactor located in Cordoba Province, Argentina, is close to reach the end-of-design-life and a project of life extension is currently ongoing. There, also the chemistry in the BOP has been modified from Morpholine to Ethanolamine chemistry (Fernandez et. al, NPC'2010, October 3-7, Quebec City, Canada) to enhance protection of steam generator internals and new steam generators will be installed. It is of interest then to set up a hide-out return procedure and analysis of blown down crud collected during the shut down as a base line for the second period of operation

  20. Modelling dewatering behaviour through an understanding of solids formation processes. Part II--solids separation considerations.

    Science.gov (United States)

    Dustan, A C; Cohen, B; Petrie, J G

    2005-05-30

    An understanding of the mechanisms which control solids formation can provide information on the characteristics of the solids which are formed. The nature of the solids formed in turn impacts on dewatering behaviour. The 'upstream' solids formation determines a set of suspension characteristics: solids concentration, particle size distribution, solution ionic strength and electrostatic surface potential. These characteristics together define the suspension's rheological properties. However, the complicated interdependence of these has precluded the prediction of suspension rheology from such a fundamental description of suspension characteristics. Recent shear yield stress models, applied in this study to compressive yield, significantly reduce the empiricism required for the description of compressive rheology. Suspension compressibility and permeability uniquely define the dewatering behaviour, described in terms of settling, filtration and mechanical expression. These modes of dewatering may be described in terms of the same fundamental suspension mechanics model. In this way, it is possible to link dynamically the processes of solids formation and dewatering of the resultant suspension. This, ultimately, opens the door to improved operability of these processes. In part I of this paper we introduced an integrated system model for solids formation and dewatering. This model was demonstrated for the upstream processes using experimental data. In this current paper models of colloidal interactions and dewatering are presented and compared to experimental results from batch filtration tests. A novel approach to predicting suspension compressibility and permeability using a single test configuration is presented and tested.

  1. 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.

  2. Production Test IP-601-D: Evaluation of crud-forming characteristics of KER loop coolant containing NH{sub 4}OH for pH control

    Energy Technology Data Exchange (ETDEWEB)

    Neidner, R.

    1963-08-06

    The objective of production test detailed in this report was to characterize the effects of NH{sub 4}OH as a pH control agent in a recirculating, high temperature and pressure water system having NPR characteristics. Of particular interest is the crud forming and decomposition characteristics of NH{sub 4}OH at potential NPR conditions.

  3. 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)

  4. 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.

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

    Directory of Open Access Journals (Sweden)

    Doyeon Kwak

    Full Text Available 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 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.

  7. Study on a corrosion products behavior with zinc injection in PWR primary circuit based on the crud investigation in actual plant

    International Nuclear Information System (INIS)

    Hisamune Kenji; Nambu Tohru; Akutagawa Daisuke; Nagata Nobuaki; Shimizu, Yuichi; Nagamine, Kunitaka; Kogawa Noritaka

    2012-09-01

    Zinc injection into the reactor coolant of Pressurized Water Reactor (PWR) is one of the most effective techniques for removing radioactive cobalt from the chromite type spinel oxides in the inner layer of reactor coolant component surfaces. Many documents have reported that zinc injection applied plants have generally achieved positive dose rate reduction effects for the reactor coolant components and piping. Tsuruga Nuclear Power Plant unit 2 (hereafter Tsuruga unit 2) which applied zinc injection in 2005 has also achieved good dose reduction effects in most primary coolant piping. However, some piping without dose-rate reduction effects exist, it has come to an issue to plan radiation exposure reduction measures for the works around relevant piping. To plan a reasonable dose-rate reduction measures for respective components and piping in primary systems, it is considered necessary to understand the dose-rate reduction effects of zinc injection mechanically. Therefore, the surface oxides/deposits on piping and fuel cladding tubes with operational histories under zinc injection were investigated. As a result of the investigation, the changes in specific aspects of oxide layers and CRUDs are found as follow: - Owing to long-term zinc injection, deposits and oxides on the primary coolant piping are extremely reduced, the boundary between the outer oxide layer and the inner oxide layer become unclear with the thinning of the outer oxide layers. - At a Pressurizer Spray Piping, the dose-rate increases than before zinc injection. The oxide layers have the same 3-layer construction as before zinc injection, and the surface concentration of the radioactive cobalt is high. - At the fuel cladding tube surfaces, what is observed is the amount of metal nickel decrease and the chromium composition increase in the spinel type oxide From these results, it is suggested that, the oxide layers composed principally of zinc chromite spinel grow up on the pipe surface with zinc

  8. Understanding molecular motor walking along a microtubule: a themosensitive asymmetric Brownian motor driven by bubble formation.

    Science.gov (United States)

    Arai, Noriyoshi; Yasuoka, Kenji; Koishi, Takahiro; Ebisuzaki, Toshikazu; Zeng, Xiao Cheng

    2013-06-12

    The "asymmetric Brownian ratchet model", a variation of Feynman's ratchet and pawl system, is invoked to understand the kinesin walking behavior along a microtubule. The model system, consisting of a motor and a rail, can exhibit two distinct binding states, namely, the random Brownian state and the asymmetric potential state. When the system is transformed back and forth between the two states, the motor can be driven to "walk" in one direction. Previously, we suggested a fundamental mechanism, that is, bubble formation in a nanosized channel surrounded by hydrophobic atoms, to explain the transition between the two states. In this study, we propose a more realistic and viable switching method in our computer simulation of molecular motor walking. Specifically, we propose a thermosensitive polymer model with which the transition between the two states can be controlled by temperature pulses. Based on this new motor system, the stepping size and stepping time of the motor can be recorded. Remarkably, the "walking" behavior observed in the newly proposed model resembles that of the realistic motor protein. The bubble formation based motor not only can be highly efficient but also offers new insights into the physical mechanism of realistic biomolecule motors.

  9. 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

  10. Understanding the formation and composition of hazes in planetary atmospheres that contain carbon monoxide

    Science.gov (United States)

    Hörst, S. M.; Yoon, Y. H.; Hicks, R. K.; Tolbert, M. A.

    2012-09-01

    Measurements from the Cassini Plasma Spectrometer (CAPS) have revealed the presence of molecules in Titan's ionosphere with masses in excess of hundreds of amu. Negative ions with mass/charge (m/z) up to 10,000 amu/q [1] and positive ions with m/z up to 400 amu/q [2] have been detected. CAPS has also observed O+ flowing into Titan's upper atmosphere [3], which appears to originate from Enceladus and is likely the source of oxygen bearing molecules in Titan's atmosphere [4]. The observed O+ is deposited in the region now known to contain large organic molecules. A recent Titan atmosphere simulation experiment has shown that incorporation of oxygen into Titan aerosol analogues results in the formation of all five nucleotide bases and the two smallest amino acids, glycine and alanine [5]. Similar chemical processes may have occurred in the atmosphere of the early Earth, or in the atmospheres of extrasolar planets; atmospheric aerosols may be an important source of the building blocks of life. Atmospheric aerosols play an important role in determining the radiation budget of an atmosphere and can also provide a wealth of organic material to the surface. The presence of atmospheric aerosols has been invoked to explain the relatively featureless spectrum of HD 189773b, including the lack of predicted atmospheric Na and K spectral lines [9]. The majority of the O+ precipitating into Titan's atmosphere forms CO (O(3P)+CH3 -> CO+H2+H) [4]. CO has also been detected in the atmospheres of a number of exoplanets including HD 189733b, HD 209458b, and WASP-12b [6-8]. It is therefore important to understand the role CO plays in the formation and composition of hazes in planetary atmospheres. Using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) (see e.g. [10]) we have obtained in situ composition measurements of aerosol particles (so-called "tholins") produced in N2/CH4/CO gas mixtures subjected to either FUV radiation (deuterium lamp, 115-400 nm) or a

  11. 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

  12. 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

  13. 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.

  14. DESENVOLVIMENTO DE UMA FERRAMENTA ASSISTENTE PARA CRIAÇÃO DE APLICAÇÕES CRUD EM JAVA NA WEB

    Directory of Open Access Journals (Sweden)

    Carlos Renato de Souza Perri

    2010-12-01

    Full Text Available Due to the need for computerization of business processes, storage of relevant information in databases and making these information available on Internet, this project proposes to develop a tool for generating Web applications written in Java, that build functionalities to perform CRUD (Create, Retrieve, Update, Delete, ie, storage, read, update and deletion. The software is a tool, from which, the programmer inserts the script to create a database and, after setting the parameters into the tool, source code of Java Web applications are generated. There is a need to create Web applications in Java with low production time, because building these applications using common methods for development takes much time. The implementation of this tool is also to change that concept and the way of developing Java Web applications, because this tool will be used as an assistant, becoming easier to create Java Web applications. The generated applications use the technologies Servlets and JSPs, the Hibernate framework and the jQuery JavaScript library.

  15. Development of nondestructive measurement system for quantifying radioactivity from crud, liquids and gases in a contaminated pipe

    Energy Technology Data Exchange (ETDEWEB)

    Katagiri, Masaki; Ito, Hirokuni; Wakayama, Naoaki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1992-11-01

    A nondestructive measuring method was developed to quantify separately radioisotope concentrations of crud, liquids and gases in a contaminated pipe. For applying this method to practical in-situ measurement, a nondestructive measurement system was developed. The measurement system consists of an in-situ equipment for gamma-ray scanning measurements and a data-processing equipment for analysis of radioactivity. The communication between both equipments is performed by a wireless telemeter device. To construct the measurement system, a gas-cooled Ge detector of practical use, small-sized electronics circuits, a fast and reliable telemeter device and automatic measurement technics using a computer were developed. Through performance tests, it is confirmed that the measurement system is effective for in-situ measurements of radioactivity in a contaminated pipe. The measurement accuracy with this measurement system is 10 - 20 %, which was determined by comparison with solid and liquid radioisotope concentrations in a mock-up contaminated pipe that had been quantified in advance. (author).

  16. Students' Understanding of Cloud and Rainbow Formation and Teachers' Awareness of Students' Performance

    Science.gov (United States)

    Malleus, Elina; Kikas, Eve; Kruus, Sigrid

    2016-01-01

    This study describes primary school students' knowledge about rainfall, clouds and rainbow formation together with teachers' predictions about students' performance. In our study, primary school students' (N = 177) knowledge about rainfall and rainbow formation was examined using structured interviews with open-ended questions. Primary school…

  17. 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…

  18. Growing Pebbles and Conceptual Prisms - Understanding the Source of Student Misconceptions about Rock Formation.

    Science.gov (United States)

    Kusnick, Judi

    2002-01-01

    Analyzes narrative essays--stories of rock formation--written by pre-service elementary school teachers. Reports startling misconceptions among preservice teachers on pebbles that grow, human involvement in rock formation, and sedimentary rocks forming as puddles as dry up, even though these students had completed a college level course on Earth…

  19. Toward Understanding Pore Formation and Mobility during Controlled Directional Solidification in a Microgravity Environment Investigation (PFMI)

    Science.gov (United States)

    Grugel, Richard N.; Anilkumar, A. V.; Luz, Paul; Jeter, Linda; Volz, Martin P.; Spivey, Reggie; Smith, G.

    2003-01-01

    The generation and inclusion of detrimental porosity, e.g., pipes and rattails can occur during controlled directional solidification processing. The origin of these defects is generally attributed to gas evolution and entrapment during solidification of the melt. On Earth, owing to buoyancy, an initiated bubble can rapidly rise through the liquid melt and pop at the surface; this is obviously not ensured in a low gravity or microgravity environment. Clearly, porosity generation and inclusion is detrimental to conducting any meaningful solidification-science studies in microgravity. Thus it is essential that model experiments be conducted in microgravity, to understand the details of the generation and mobility of porosity, so that methods can be found to eliminate it. In hindsight, this is particularly relevant given the results of the previous directional solidification experiments conducted in Space. The current International Space Station (ISS) Microgravity Science Glovebox (MSG) investigation addresses the central issue of porosity formation and mobility during controlled directional solidification processing in microgravity. The study will be done using a transparent metal-analogue material, succinonitrile (SCN) and succinonitrile-water 'alloys', so that direct observation and recording of pore generation and mobility can be made during the experiments. Succinonitrile is particularly well suited for the proposed investigation because it is transparent, it solidifies in a manner analogous to most metals, it has a convenient melting point, its material properties are well characterized and, it has been successfully used in previous microgravity experiments. The PFMI experiment will be launched on the UF-2, STS-111 flight. Highlighting the porosity development problem in metal alloys during microgravity processing, the poster will describe: (i) the intent of the proposed experiments, (ii) the theoretical rationale behind using SCN as the study material for

  20. Understanding triplet formation pathways in bulk heterojunction polymer : fullerene photovoltaic devices

    NARCIS (Netherlands)

    Tedla, B.; Zhu, F.; Cox, M.; Drijkoningen, J.; Manca, J.V.; Koopmans, B.; Goovaerts, E.

    2015-01-01

    Triplet exciton (TE) formation pathways are systematically investigated in prototype bulk heterojunction (BHJ) "super yellow" poly(p-phenylene vinylene) (SY-PPV) solar cell devices with varying fullerene compositions using complementary optoelectrical and electrically detected magnetic resonance

  1. Understanding the operational parameters affecting NDMA formation at Advanced Water Treatment Plants.

    Science.gov (United States)

    Farré, Maria José; Döderer, Katrin; Hearn, Laurence; Poussade, Yvan; Keller, Jurg; Gernjak, Wolfgang

    2011-01-30

    N-nitrosodimethylamine (NDMA) can be formed when secondary effluents are disinfected by chloramines. By means of bench scale experiments this paper investigates operational parameters than can help Advanced Water Treatment Plants (AWTPs) to reduce the formation of NDMA during the production of high quality recycled water. The formation of NDMA was monitored during a contact time of 24h using dimethylamine as NDMA model precursor and secondary effluent from wastewater treatment plants. The three chloramine disinfection strategies tested were pre-formed and in-line formed monochloramine, and pre-formed dichloramine. Although the latter is not employed on purpose in full-scale applications, it has been suggested as the main contributing chemical generating NDMA during chloramination. After 24h, the NDMA formation decreased in both matrices tested in the order: pre-formed dichloramine>in-line formed monochloramine≫pre-formed monochloramine. The most important parameter to consider for the inhibition of NDMA formation was the length of contact time between disinfectant and wastewater. Formation of NDMA was initially inhibited for up to 6h with concentrations consistently NDMA concentrations were reduced by a factor of 20 by optimizing the disinfection strategy. Copyright © 2010 Elsevier B.V. All rights reserved.

  2. Corrosion product balances for the Ringhals PWR plants based on extensive fuel crud and water chemistry measurements

    International Nuclear Information System (INIS)

    Lundgren, K.; Wikmark, G.; Bengtsson, B.

    2010-01-01

    The corrosion product balance in a PWR plant is of great importance for the fuel performance as well as for the radiation field buildup. This balance is of special concern in connection to steam generator replacement (SGR) and power uprate projects. The Ringhals PWRs are all of Westinghouse design. Two of the plants have performed Steam Generator Replacement (SGR) to I-690 SG tubes and such a replacement is being planned in the third and last unit in 2011. Two of the units are in different phases of power uprate projects. The plants are all on 10-14-months cycles operating with medium to high fuel duty. Water chemistry is controlled by a pH300 in the range ∼7.2 to 7.4 from beginning of cycle to end of cycle (BOC-EOC) in the units with new SGs while kept at a coordinated pH of 7.2 in the one still using I-600. The maximum Li content has recently been increased to about 4.5 to 5 ppm in all units. In order to be able to improve the assessment of corrosion product balances in the plants, comprehensive fuel crud measurements were performed in 2007. Improved integrated reactor water sampling techniques have also been introduced in order to make accurate mass balances possible. The corrosion products covered in the study are the main constituents, Ni, Fe and Cr in the primary circuit Inconel and stainless steel, together with Co. The activated corrosion products, Co-58, Co-60, Cr-51, Fe-59 and Mn-54, are all mainly produced through neutron irradiation of the covered corrosion products. The main results of the corrosion product balances are presented. Observed differences between the plants, indicating significant impact of pH control and SG tube materials, are presented and discussed. The importance of accurate sampling techniques is especially addressed in this paper. (author)

  3. 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.

  4. 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...

  5. 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

    control on glycolysis and growth rate but high negative control on formate production. We find that PFK and PK have zero control on glycolysis and growth rate at the wildtype enzyme level but both enzymes exert strong positive control on the glycolytic flux at reduced activities. PK has high positive...... coefficient increased towards 3. Increased las expression resulted in a slight decrease in the glycolytic flux. At the wildtype level the control was close to zero on both glycolysis and the pyruvate branches. The sum of control coefficients for the three enzymes individually was comparable to the 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...

  6. Population I Cepheids and understanding star formation history of the Small Magellanic Cloud

    International Nuclear Information System (INIS)

    Joshi, Yogesh Chandra; Joshi, Santosh; Mohanty, Auro Prasad

    2016-01-01

    In this paper, we study the age and spatial distributions of Cepheids in the Small Magellanic Cloud (SMC) as a function of their ages using data from the OGLE III photometric catalogue. A period - age relation derived for Classical Cepheids in the Large Magellanic Cloud (LMC) has been used to find the ages of Cepheids. The age distribution of the SMC Classical Cepheids is found to have a peak at log(Age) = 8.40 ± 0.10 which suggests that a major star formation event might have occurred in the SMC about 250 ± 50 Myr ago. It is believed that this star forming burst had been triggered by close interactions of the SMC with the LMC and/or the Milky Way. A comparison of the observed spatial distributions of the Cepheids and open star clusters has also been carried out to study the star formation scenario in the SMC. (paper)

  7. UNDERSTANDING COMPACT OBJECT FORMATION AND NATAL KICKS. II. THE CASE OF XTE J1118 + 480

    International Nuclear Information System (INIS)

    Fragos, T.; Willems, B.; Kalogera, V.; Ivanova, N.; Rockefeller, G.; Fryer, C. L.; Young, P. A.

    2009-01-01

    In recent years, an increasing number of proper motions have been measured for Galactic X-ray binaries. When supplemented with accurate determinations of the component masses, orbital period, and donor effective temperature, these kinematical constraints harbor a wealth of information on the system's past evolution. Here, we consider all this available information to reconstruct the full evolutionary history of the black hole X-ray binary XTE J1118 + 480, assuming that the system originated in the Galactic disk and the donor has solar metallicity. This analysis accounts for four evolutionary phases: mass transfer through the ongoing X-ray phase, tidal evolution before the onset of Roche lobe overflow, motion through the Galactic potential after the formation of the black hole, and binary orbital dynamics due to explosive mass loss and possibly a black hole natal kick at the time of core collapse. We find that right after black hole formation, the system consists of a ≅6.0-10.0 M sun black hole and a ≅1.0-1.6 M sun main-sequence star. We also find that that an asymmetric natal kick is not only plausible but required for the formation of this system, and derive a lower and upper limit on the black hole natal kick velocity magnitude of 80 km s -1 and 310 km s -1 , respectively.

  8. Understanding perovskite formation through the intramolecular exchange method in ambient conditions

    Science.gov (United States)

    Szostak, Rodrigo; Castro, Jhon A. P.; Marques, Adriano S.; Nogueira, Ana F.

    2017-04-01

    Among the methods to prepare hybrid organic-inorganic perovskite films, the intramolecular exchange method was the first one that made possible to prepare perovskite solar cells with efficiencies higher than 20%. However, perovskite formation by this method is not completely understood, especially in ambient conditions. In this work, perovskite films were prepared by the intramolecular exchange method in ambient conditions. The spin coating speed and the frequency of the MAI solution dripping onto PbI2(DMSO) were varied during the deposition steps. With the combination of these two parameters, a rigid control of the solvent drying was possible. Thus, depending on the chosen conditions, the intermediate MAPb3I8·2DMSO was formed with residual PbI2. Otherwise, direct formation of perovskite film was attained. A mechanism for the direct formation of bulk perovskite was proposed. We also investigated how the posterior thermal annealing affects the crystallinity and defects in perovskite films. With prolonged thermal annealing, the excess of MAI can be avoided, increasing the efficiency and decreasing the hysteresis of the solar cells. The best perovskite solar cell achieved a stabilized power output of 12.9%. The findings of this work pave the way for realizing the fabrication of efficient perovskite solar cells in ambient atmosphere, a very desirable condition for cost-efficient large scale manufacturing of this technology.

  9. How relevant are assembled equilibrium samples in understanding structure formation during lipid digestion?

    Science.gov (United States)

    Phan, Stephanie; Salentinig, Stefan; Hawley, Adrian; Boyd, Ben J

    2015-10-01

    Lipid-based formulations are gaining interest for use as drug delivery systems for poorly water-soluble drug compounds. During digestion, the lipolysis products self-assemble with endogenous surfactants in the gastrointestinal tract to form colloidal structures, enabling enhanced drug solubilisation. Although earlier studies in the literature focus on assembled equilibrium systems, little is known about structure formation under dynamic lipolysis conditions. The purpose of this study was to investigate the likely colloidal structure formation in the small intestine after the ingestion of lipids, under equilibrium and dynamic conditions. The structural aspects were studied using small angle X-ray scattering and dynamic light scattering, and were found to depend on lipid composition, lipid chain length, prandial state and emulsification. Incorporation of phospholipids and lipolysis products into bile salt micelles resulted in swelling of the structure. At insufficient bile salt concentrations, a co-existing lamellar phase was observed, due to a reduction in the solubilisation capacity for lipolysis products. Emulsification accelerated the rate of lipolysis and structure formation. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. 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

    solution of C$_60$. We have performed a thorough theoretical analysis, aiming at gaining an in-depth understanding of the exceptionally large aspect ratio of C$_60$-based nanowires. By accounting for different interactions in the system we have calculated the structures of the unit cell and determined...... the role of the fullerene and of the solvent molecules in the crystallization process of the nanowires. We have calculated the adhesion energy of C$_60$ molecules to the nanowire surface, and on the basis of this explained the growth anisotropy of the crystal. To get a more profound understanding...

  11. Higher-level processes in the formation and application of associations during action understanding

    NARCIS (Netherlands)

    Heil, L.; Pelt, S. van; Kwisthout, J.H.P.; Rooij, I.J.E.I. van; Bekkering, H.

    2014-01-01

    The associative account described in the target article provides a viable explanation for the origin of mirror neurons. We argue here that if mirror neurons develop purely by associative learning, then they cannot by themselves explain intentional action understanding. Higher-level processes seem to

  12. Understanding hydride formation in Zr-1Nb alloy through microstructural characterization

    International Nuclear Information System (INIS)

    Neogy, S.; Srivastava, D.; Tewari, R.; Singh, R.N.; Dey, G.K.; De, P.K.; Banerjee, S.

    2003-07-01

    In this study the experimental results of hydride formation and their microstructure evolution in Zr-1Nb alloy is presented. This Zr-1Nb binary alloy and other Zr-1 Nb based ternary and quaternary alloys are being used as fuel tube materials and have the potential for meeting the requirement of high burn up fuel. Hydriding of Zr-1Nb alloy having a microstructure comprising equiaxed α grains and a uniform distribution of spherical particles of the β phase has been carried out in this study. The specimens have been hydrided by gaseous charging method to different hydrogen levels. The microstructures of hydrided samples were examined as a function of hydrogen content. The formation of δ hydride in slow cooled specimens and formation of γ hydride in rapidly cooled specimens has been studied with their morphology, habit plane and orientation relationship with the α matrix in view. The habit planes of either type of hydride phase has been determined and compared with those observed in other Zr-Nb alloys. The orientation relationship between the α matrix and the δ hydride was found to be the following: (0001) α // (111) δ and [1120] α // [110] δ . The orientation relationship between the α matrix and the γ hydride was of the following type: (0001) α // (111) γ and [1120] α // [110] γ . The internal structure of both types of hydride has been examined. The effect of the presence of the spherical β phase particles in the a matrix on the growth of the hydride plates has been investigated. (author)

  13. Using Laboratory Methods to Better Understand Refractory Cloud Formation in Exoplanet Atmospheres

    Science.gov (United States)

    Kohler, E.; Ferguson, F.

    2017-12-01

    The high number of extrasolar planets found in recent years has brought a new importance to planetary atmospheres. These recently discovered planets show a large diversity in their masses, temperatures, orbital periods, and other properties. With such a diverse mix of planetary parameters, it is safe to assume that the atmospheric properties are just as varied. Recent literature suggests silicates and metals as possible condensates in extrasolar planetary atmospheres as well as the atmospheres of brown dwarfs. While theoretical studies have laid the foundation of cloud formation analysis, their findings still need to be validated via experiments. A verification of the condensation and vaporization predictions of refractory materials needs to be found in order to assist global circulation models in being as accurate as possible. The stability of minerals identified in the literature as potential candidates, will be tested in a thermogravimetric balance. The minerals will be pumped under vacuum for twenty-four hours under room temperature and then heated to a predetermined high temperature, dependent on the expected vaporization temperature of that sample. If there is apparent mass loss, then the temperature will be lowered at preset durations and mass measurements will be taken in similar measured increments. The data will be processed by a computer program in order to calculate the mass loss as a function of temperature. The current cloud formation and global circulation models are very important to the field of planetary science but their accuracy is hindered by the lack of experimental data. The aim of this work is to investigate the mineral stability of potential condensates in an effort to explain the formation of refractory clouds in the atmospheres of extrasolar planets and brown dwarfs.

  14. Observational Corollaries of Proto-AGN: Understanding Formation of Supermassive Black Hole Seeds

    Science.gov (United States)

    Shlosman, Isaac

    2016-10-01

    Formation of supermassive black holes (SMBHs) is still an enigma. Recent detections of high-z quasars which harbor massive SMBHs provide a challenge to models of structure buildup in the universe. Main alternatives for the formation of SMBH seeds are (1) remnants of Population III stars, and (2) a direct baryonic collapse within dark matter (DM) halos of 10^8 Mo -- first halos whose virial temperature exceeds 10^4 K, and which can lead to the formation of proto-AGN -- luminous pre-SMBH objects. Potentially, this can involve both high-z objects as well as low-z dwarf galaxies in voids. We focus on the direct collapse in 10^8 Mo halos which circumvents the pitfalls of Pop III remnants. The collapse can proceed via a radiation pressure-supported quasistar -- with a modified blackbody continuum. Such a configuration requires a very efficient angular momentum transfer. Or, it can form a thick, differentially rotating, self-gravitating disk, which is associated with an X-ray-infrared continuum and Seyfert-level luminosity, anisotropic emission, massive bi-conical outflows, and will be a powerful source of the Ly-alpha emission. We propose to perform radiative transfer in the continuum and hydrogen lines (e.g., Lyman and Balmer), using our models of proto-AGN, and do it on-the-fly -- concurrently with the collapse. We shall test the path to quasistellar and disky proto-AGN, produce first synthetic spectra of proto-AGN, and address the issue of feasibility of their detection by the JWST. Finally, we shall develop the strategy of searching for these objects at high- and low-z, based on the specific features in the spectra and associated variability.

  15. 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.)

  16. Towards an understanding of the propensity for crystalline hydrate formation by molecular compounds

    Directory of Open Access Journals (Sweden)

    Alankriti Bajpai

    2016-11-01

    Full Text Available Hydrates are technologically important and ubiquitous yet they remain a poorly understood and understudied class of molecular crystals. In this work, we attempt to rationalize propensity towards hydrate formation through crystallization studies of molecules that lack strong hydrogen-bond donor groups. A Cambridge Structural Database (CSD survey indicates that the statistical occurrence of hydrates in 124 molecules that contain five- and six-membered N-heterocyclic aromatic moieties is 18.5%. However, hydrate screening experiments on a library of 11 N-heterocyclic aromatic compounds with at least two acceptor moieties and no competing hydrogen-bond donors or acceptors reveals that over 70% of this group form hydrates, suggesting that extrapolation from CSD statistics might, at least in some cases, be deceiving. Slurrying in water and exposure to humidity were found to be the most effective discovery methods. Electrostatic potential maps and/or analysis of the crystal packing in anhydrate structures was used to rationalize why certain molecules did not readily form hydrates.

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

    Science.gov (United States)

    Sinkemani, Arjun; Xie, Zhi-Yang; Shi, Rui; Wei, Ji-Nan; Wu, Xiao-Tao

    2017-01-01

    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. PMID:28915712

  18. 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)

  19. Making comparative performance information more comprehensible: an experimental evaluation of the impact of formats on consumer understanding.

    Science.gov (United States)

    Damman, Olga C; De Jong, Anco; Hibbard, Judith H; Timmermans, Danielle R M

    2016-11-01

    We aimed to investigate how different presentation formats influence comprehension and use of comparative performance information (CPI) among consumers. An experimental between-subjects and within-subjects design with manipulations of CPI presentation formats. We enrolled both consumers with lower socioeconomic status (SES)/cognitive skills and consumers with higher SES/cognitive skills, recruited through an online access panel. Respondents received fictitious CPI and completed questions about interpretation and information use. Between subjects, we tested (1) displaying an overall performance score (yes/no); (2) displaying a small number of quality indicators (5 vs 9); and (3) displaying different types of evaluative symbols (star ratings, coloured dots and word icons vs numbers and bar graphs). Within subjects, we tested the effect of a reduced number of healthcare providers (5 vs 20). Data were analysed using descriptive analysis, analyses of variance and paired-sampled t tests. A total of 902 (43%) respondents participated. Displaying an overall performance score and the use of coloured dots and word icons particularly enhanced consumer understanding. Importantly, respondents provided with coloured dots most often correctly selected the top three healthcare providers (84.3%), compared with word icons (76.6% correct), star ratings (70.6% correct), numbers (62.0%) and bars (54.2%) when viewing performance scores of 20 providers. Furthermore, a reduced number of healthcare providers appeared to support consumers, for example, when provided with 20 providers, 69.5% correctly selected the top three, compared with 80.2% with five providers. Particular presentation formats enhanced consumer understanding of CPI, most importantly the use of overall performance scores, word icons and coloured dots, and a reduced number of providers displayed. Public report efforts should use these formats to maximise impact on consumers. Published by the BMJ Publishing Group Limited

  20. The impact of Einstein observations on our understanding of low mass star formation

    International Nuclear Information System (INIS)

    Walter, F.M.

    1990-01-01

    Prior to 1980, the world of pre-main sequence stars, if not well understood, was at least well defined. The Herbig and Rao (1972) catalog listed 69 pre-main sequence stars in Tau-Aur, with the vast majority clearly being T Tauri stars. The characteristics of the classical T Tauri stars include strong Hα emission, with W λ (Hα)>5-10A; forbidden line emission; continuum ultraviolet and IR excesses; veiling of the absorption line spectrum; significant stellar variability; Li I λ6707A absorption; and association with dark clouds and/or emission nebulosities. Star forming regions were observed extensively with the Einstein Observatory, and showed the abundance of stellar X-ray sources in the Orion Nebula. About 1/3 of the known T Tauri stars were detected as X-ray sources, yet the vast majority of the X-ray sources detected were coincident with anonymous stars not suspected to be pre-main sequence stars. In the grand tradition of X-ray astronomy, X-ray astronomers trooped to telescopes to identify the optical counterparts. It was shown that 5 of the counterparts were K7-M0 stars, above the main sequence, with strong Li I absorption and that these stars were kinematic members of the Tau-Aur star formation complex. Since then, additional members of this class of naked T Tauri Stars (NTTS) have been studied, and charts provided for X-ray selected pre-main sequence star candidates in the general vicinity of Tau-Aur. Thirty five X-ray sources have been selected and optically confirmed as NTTS in Tau-Aur

  1. 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.

  2. 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

  3. 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

  4. A randomized comparison of patients' understanding of number needed to treat and other common risk reduction formats.

    Science.gov (United States)

    Sheridan, Stacey L; Pignone, Michael P; Lewis, Carmen L

    2003-11-01

    Commentators have suggested that patients may understand quantitative information about treatment benefits better when they are presented as numbers needed to treat (NNT) rather than as absolute or relative risk reductions. To determine whether NNT helps patients interpret treatment benefits better than absolute risk reduction (ARR), relative risk reduction (RRR), or a combination of all three of these risk reduction presentations (COMBO). Randomized cross-sectional survey. University internal medicine clinic. Three hundred fifty-seven men and women, ages 50 to 80, who presented for health care. Subjects were given written information about the baseline risk of a hypothetical "disease Y" and were asked (1) to compare the benefits of two drug treatments for disease Y, stating which provided more benefit; and (2) to calculate the effect of one of those drug treatments on a given baseline risk of disease. Risk information was presented to each subject in one of four randomly allocated risk formats: NNT, ARR, RRR, or COMBO. When asked to state which of two treatments provided more benefit, subjects who received the RRR format responded correctly most often (60% correct vs 43% for COMBO, 42% for ARR, and 30% for NNT, P =.001). Most subjects were unable to calculate the effect of drug treatment on the given baseline risk of disease, although subjects receiving the RRR and ARR formats responded correctly more often (21% and 17% compared to 7% for COMBO and 6% for NNT, P =.004). Patients are best able to interpret the benefits of treatment when they are presented in an RRR format with a given baseline risk of disease. ARR also is easily interpreted. NNT is often misinterpreted by patients and should not be used alone to communicate risk to patients.

  5. Nice to know you: Positive emotions, self-other overlap, and complex understanding in the formation of a new relationship.

    Science.gov (United States)

    Waugh, Christian E; Fredrickson, Barbara L

    2006-04-01

    Based on Fredrickson's ((1998). What good are positive emotions? Review of General Psychology, 2, 300-319.; (2001). The role of positive emotions in positive psychology: The broaden-and-build theory of positive emotions. American Psychologist, 56, 218-226) broaden-and-build theory and Aron and Aron's ((1986). Love as expansion of the self: Understanding attraction and satisfaction. New York: Hemisphere) self-expansion theory, it was hypothesized that positive emotions broaden people's feelings of self-other overlap in the beginning of a new relationship. In a prospective study of first-year college students, we found that, after 1 week in college, positive emotions predicted increased self-other overlap with new roommates, which in turn predicted a more complex understanding of the roommate. In addition, participants who experienced a high ratio of positive to negative emotions throughout the first month of college reported a greater increase in self-other overlap and complex understanding than participants with a low positivity ratio. Implications for the role of positive emotions in the formation of new relationships are discussed.

  6. Nice to know you: Positive emotions, self–other overlap, and complex understanding in the formation of a new relationship

    Science.gov (United States)

    WAUGH, CHRISTIAN E.; FREDRICKSON, BARBARA L.

    2007-01-01

    Based on Fredrickson's ((1998). What good are positive emotions? Review of General Psychology, 2, 300–319.; (2001). The role of positive emotions in positive psychology: The broaden-and-build theory of positive emotions. American Psychologist, 56, 218–226) broaden-and-build theory and Aron and Aron's ((1986). Love as expansion of the self: Understanding attraction and satisfaction. New York: Hemisphere) self-expansion theory, it was hypothesized that positive emotions broaden people's feelings of self–other overlap in the beginning of a new relationship. In a prospective study of first-year college students, we found that, after 1 week in college, positive emotions predicted increased self–other overlap with new roommates, which in turn predicted a more complex understanding of the roommate. In addition, participants who experienced a high ratio of positive to negative emotions throughout the first month of college reported a greater increase in self–other overlap and complex understanding than participants with a low positivity ratio. Implications for the role of positive emotions in the formation of new relationships are discussed. PMID:21691460

  7. A multiscale modelling approach to understand atherosclerosis formation: A patient-specific case study in the aortic bifurcation

    Science.gov (United States)

    Alimohammadi, Mona; Pichardo-Almarza, Cesar; Agu, Obiekezie; Díaz-Zuccarini, Vanessa

    2017-01-01

    Atherogenesis, the formation of plaques in the wall of blood vessels, starts as a result of lipid accumulation (low-density lipoprotein cholesterol) in the vessel wall. Such accumulation is related to the site of endothelial mechanotransduction, the endothelial response to mechanical stimuli and haemodynamics, which determines biochemical processes regulating the vessel wall permeability. This interaction between biomechanical and biochemical phenomena is complex, spanning different biological scales and is patient-specific, requiring tools able to capture such mathematical and biological complexity in a unified framework. Mathematical models offer an elegant and efficient way of doing this, by taking into account multifactorial and multiscale processes and mechanisms, in order to capture the fundamentals of plaque formation in individual patients. In this study, a mathematical model to understand plaque and calcification locations is presented: this model provides a strong interpretability and physical meaning through a multiscale, complex index or metric (the penetration site of low-density lipoprotein cholesterol, expressed as volumetric flux). Computed tomography scans of the aortic bifurcation and iliac arteries are analysed and compared with the results of the multifactorial model. The results indicate that the model shows potential to predict the majority of the plaque locations, also not predicting regions where plaques are absent. The promising results from this case study provide a proof of concept that can be applied to a larger patient population. PMID:28427316

  8. Understanding the Formation of Kinetically Stable Compounds and the Development of Thin Film Pair Distribution Function Analysis

    Science.gov (United States)

    Wood, Suzannah Rebecca

    Navigating the synthesis landscape poses many challenges when developing novel solid state materials. Advancements in both synthesis and characterization are necessary to facilitate the targeting of specific materials. This dissertation discusses the formation of chalcogenide heterostructures and their properties in the first part and the development of thin film pair distribution function analysis (tfPDF) in the second part. The heterostructures were formed by the self-assembly of designed precursors deposited by physical vapor deposition in a modulated elemental reactants approach, which provides the control and predictability to synthesis. Specifically, a series of (BiSe)1+delta(TiSe2) n, where n = 2,3,&4, were synthesized to explore the extent of charge transfer from the BiSe to TiSe2 layers. To further explore the role Bi plays in charge donation, a family of structurally similar compounds, (Bix Sn1-xSe)1+deltaTiSe2, where 0≥x≥1, were synthesized and characterized. Electrical measurements show doping efficiency decreases as x increases, correlated with the structural distortion and the formation of periodic antiphase boundaries containing Bi-Bi pairs. The first heterostructures composed of three unique structural types were synthesized and Bi2Se3 layer thickness was used to tune electrical properties and further explore charge transfer. To better understand the potential energy landscape on which these kinetically stable compounds exist, two investigations were undertaken. The first was a study of the formation and subsequent decomposition of [(BiSe)1+delta]n(TiSe2)n compounds, where n= 2&3, the second an investigation of precursor structure for thermodynamically stable FeSb2 and kinetically stable FeSb3. The second section describes the development of thin film pair distribution function analysis, a technique in which total scattering data for pair distribution function (PDF) analysis is obtained from thin films, suitable for local structure analysis

  9. Using quantitative magnetic resonance methods to understand better the gel-layer formation on polymer-matrix tablets.

    Science.gov (United States)

    Mikac, Urša; Kristl, Julijana; Baumgartner, Saša

    2011-05-01

    Magnetic resonance imaging is a powerful, non-invasive technique that can help improve our understanding of the hydrogel layer formed on swellable, polymer-matrix tablets, as well as the layer's properties and its influence on drug release. In this paper, the authors review the NMR and MRI investigations of hydrophilic, swellable polymers published since 1994. The review covers NMR studies on the properties of water and drugs within hydrated polymers. In addition, MRI studies using techniques for determining the different moving-front positions within the swollen tablets, the polymer concentration profiles across them, the influence of the incorporated drug, and so on, are presented. Some complementary methods are also briefly presented and discussed. Using MRI, the formation of a hydrogel along with simultaneous determination of the drug's position within it can be observed non-invasively. However, the MRI parameters can influence the signal's intensity and therefore they need to be considered carefully in order to prevent any misinterpretation of the results. MRI makes possible an in situ investigation of swollen-matrix tablets and provides valuable information that can lead, when combined with other techniques, to a better understanding of polymeric systems and a more effective development of optimal dosage forms.

  10. Understanding Oxygen Vacancy Formation, Interaction, Transport, and Strain in SOFC Components via Combined Thermodynamics and First Principles Calculations

    Science.gov (United States)

    Das, Tridip

    Understanding of the vacancy formation, interaction, increasing its concentration and diffusion, and controlling its chemical strain will advance the design of mixed ionic and electronic conductor (MIEC) materials via element doping and strain engineering. This is especially central to improve the performance of the solid oxide fuel cell (SOFC), an energy conversion device for sustainable future. The oxygen vacancy concentration grows exponentially with the temperature at dilute vacancy concentration but not at higher concentration, or even decreases due to oxygen vacancy interaction and vacancy ordered phase change. This limits the ionic conductivity. Using density functional theory (DFT), we provided fundamental understanding on how oxygen vacancy interaction originates in one of the typical MIEC, La1-xSrxFeO3-delta (LSF). The vacancy interaction is determined by the interplay of the charge state of multi-valence ion (Fe), aliovalent doping (La/Sr ratio), the crystal structure, and the oxygen vacancy concentration and/or nonstoichiometry (delta). It was found excess electrons left due to the formation of a neutral oxygen vacancy get distributed to Fe directly connected to the vacancy or to the second nearest neighboring Fe, based on crystal field splitting of Fe 3d orbital in different Fe-O polyhedral coordination. The progressively larger polaron size and anisotropic shape changes with increasing Sr-content resulted in increasing oxygen vacancy interactions, as indicated by an increase in the oxygen vacancy formation energy above a critical delta threshold. This was consistent with experimental results showing that Sr-rich LSF and highly oxygen deficient compositions are prone to oxygen-vacancy-ordering-induced phase transformations, while Sr-poor and oxygen-rich LSF compositions are not. Since oxygen vacancy induced phase transformations, cause a decrease in the mobile oxygen vacancy site fraction (X), both delta and X were predicted as a function of

  11. 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

  12. 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.

  13. 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.

  14. 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...

  15. 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.

  16. 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

    Deposit formation in utility boilers occurs via a number of consecutive steps; 1) release of critical elements like K, Na, Pb, Zn, S and Cl, 2) formation of gaseous species, fly ash and aerosols, 3) transport and adhesion of ash species, 4) deposit build-up and consolidation, and, finally, 5...... formation (slagging and fouling) on superheater tubes, leading to a potential reduction in heat transfer efficiency to the water/steam cycle, or, to chemical attack (corrosion) or physical wear (erosion) of superheater tubes. These problems may give rise to irregular operation, or even costly shutdowns...... 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...

  17. 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.

  18. Characterization of iodine species in the marine aerosol:to understand their roles in particle formation processes

    Institute of Scientific and Technical Information of China (English)

    Hongwei Chen; Rolf Brandt; Rolf Bandur; Thorsten Hoffmann

    2006-01-01

    In this contribution,iodine chemistry in the Marine Boundary Layer(MBL)is introduced.A series of methodologies for the measurements of iodine species in the gas and particle phases of the coastal atmosphere has been developed.Iodine species in the gas phase in real air samples has been determined in two field campaigns at the west coast of Ireland,indicating that gaseous iodo-hydrocarbons and elemental iodine are the precursors of new particle formation.Particulate iodine speciation from the same measurement campaigns show that the non-water-soluble iodine compounds are the main iodine species during the marine particle formation.A seaweed-chamber experiment was performed,indicating that gaseous I2 is one of the important precursors that lead to new particle formation in the presence of solar light in the ambient air at the coastal tidal area.

  19. HOBYS and W43-HERO: Two more steps toward a Galaxy-wide understanding of high-mass star formation

    Science.gov (United States)

    Motte, Frédérique; Bontemps, Sylvain; Tigé, Jérémy

    The Herschel/HOBYS key program allows to statistically study the formation of 10-20 M ⊙ stars. The IRAM/W43-HERO large program is itself dedicated to the much more extreme W43 molecular complex, which forms stars up to 50 M ⊙. Both reveal high-density cloud filaments of several pc3, which are forming clusters of OB-type stars. Given their activity, these so-called mini-starburst cloud ridges could be seen as ``miniature and instant models'' of starburst galaxies. Both surveys also strongly suggest that high-mass prestellar cores do not exist, in agreement with the dynamical formation of cloud ridges. The HOBYS and W43 surveys are necessary steps towards Galaxy-wide studies of high-mass star formation.

  20. 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...

  1. Opinion Formation on Environmental Protection: Understanding the Origins of Attitudes toward Resource Enhancement and Protection in Iowa.

    Science.gov (United States)

    Rodriguez, Lulu; Farnall, Olan; Geske, Joel; Peterson, Jane W.

    1998-01-01

    A study of 483 Iowa citizens and state legislators found that self-interest had the strongest effect on formation of opinions toward environmental protection; sociotropic and symbolic politics models were also effective. Results indicate that campaign messages must stress the benefits of environmental protection to the individual. (JOW)

  2. Critical Incidents as Formative Influences on the Work of Educational Researchers: Understanding an Insider Perspective through Narrative Enquiry

    Science.gov (United States)

    Holligan, Chris; Wilson, Michael

    2015-01-01

    Drawing on insights from phenomenological sociology and various strands of socio-cultural theory, this paper reports the findings of a qualitative investigation into critical incidents as formative influences in the research orientation and research cultivation of 22 academics working in research-intensive university education departments. The…

  3. A multidisciplinary environmental integrated approach to better understand the Tegnue Reefs formation, offshore Chioggia, Northern Adriatic Sea.

    Science.gov (United States)

    Bergamasco, Andrea; Donnici, Sandra; Tosi, Luigi; Tagliapietra, Davide; Zaggia, Luca; Bonaldo, Davide; Braga, Federica; Da Lio, Cristina; Keppel, Erica; Lorenzetti, Giuliano; Manfè, Giorgia; Franceschini, Gianluca; Giovanardi, Otello; Carol, Eleonora; Fornaro, Elena; Grant, Carley

    2014-05-01

    Several hard substrata cover the northwestern Adriatic shelf around 20 m depth as patchy reefs called 'Tegnue'. These submerged reefs form many discrete sets from offshore Grado south to the Po river delta with a large field located off Chioggia. Even if the outer part of the reef is constituted by a thick biogenic formation the underlying structure, mainly buried, is made by cemented sand and this seems to be correlated with its origin not yet fully understood. Different genetic interpretations have been proposed thus far, contemplating among other cementation due to beach-rock like processes (e.g., Stefanon, 1969, Bonardi and Tosi, 2002, Bonardi et al., 2006) or the action of ascending fluids enriched in hydrocarbons (e.g., Gabbianelli et al., 1997, Casellato and Stefanon, 2008). An on-going project, mainly a multidisciplinary integrated approach, combining physical, biological, geological, geomorphological, hydrogeological and geochemical data, supported by a detailed bathymetric mapping, an overall general circulation modeling at high resolution, a robust geophysical evidence, and detailed underwater surveys performed by a team of scuba-diver scientists, aims to better understand the genetic processes backing the distribution, early genesis and evolution of such relevant habitats. Actually, using all the new available data, our plan is to verify which previous interpretations on the origin of the Tegnue core better match with the diagenetic processes that led to the cementation of the sand layers lying at the base of the organic reefs. Preliminary results suggest that the Tegnue reefs formed along paleochannels features related to the former alluvial plain and submerged by the Holocene transgression. Whatever their genesis, once exposed such rocky substrata are then quickly colonized by living organisms, which contribute to the growth and expansion of the reef. Calcareous algae and in general the organic concretion could have a role during the reef accretion

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

    Science.gov (United States)

    Gonsalves, Catherine; Zaidi, Zareen

    2016-01-01

    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. 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. 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. 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.

  5. 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

  6. 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

  7. A proteomic and metabolomic approach for understanding the role of the flor yeast mitochondria in the velum formation.

    Science.gov (United States)

    Moreno-García, Jaime; García-Martínez, Teresa; Moreno, Juan; Millán, M Carmen; Mauricio, Juan Carlos

    2014-02-17

    Saccharomyces cerevisiae "flor" yeast shows a strong tolerance to high ethanol concentrations and develops a velum (biofilm) on the wine surface after the alcoholic fermentation of grape must. This velum remains along several years during the so called "biological aging" process in the elaboration of some special wines carried out in specific regions around the world and it contributes to the typical organoleptic characteristics of these wines. In order to grow in this condition, flor yeast has to elaborate a response where the mitochondrial function is essential. The objective of this study is to elucidate the role of the mitochondria in the response of a flor yeast, S. cerevisiae G1, growing in a controlled velum formation condition. For this purpose, proteome and metabolome were characterized by comparing data with those from an initial fermentative condition used as reference. The obtained proteomic profiles show more mitochondrial proteins related with the ethanol resistance (13), cell respiration (18), mitochondrial genome maintenance (13), and apoptosis (2) detected under the velum formation condition. Also, the finger-printing obtained by means of the exo-metabolites directly related with the quality of fermented beverages and quantified in the velum condition shows important differences from those obtained in the reference condition. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Nice to know you: Positive emotions, self–other overlap, and complex understanding in the formation of a new relationship

    OpenAIRE

    WAUGH, CHRISTIAN E.; FREDRICKSON, BARBARA L.

    2006-01-01

    Based on Fredrickson's ((1998). What good are positive emotions? Review of General Psychology, 2, 300–319.; (2001). The role of positive emotions in positive psychology: The broaden-and-build theory of positive emotions. American Psychologist, 56, 218–226) broaden-and-build theory and Aron and Aron's ((1986). Love as expansion of the self: Understanding attraction and satisfaction. New York: Hemisphere) self-expansion theory, it was hypothesized that positive emotions broaden people's feeling...

  9. 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

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. Understanding the spatial formation and accumulation of fats, oils and grease deposits in the sewer collection system.

    Science.gov (United States)

    Dominic, Christopher Cyril Sandeep; Szakasits, Megan; Dean, Lisa O; Ducoste, Joel J

    2013-01-01

    Sanitary sewer overflows are caused by the accumulation of insoluble calcium salts of fatty acids, which are formed by the reaction between fats, oils and grease (FOG) and calcium found in wastewaters. Different sewer structural configurations (i.e., manholes, pipes, wet wells), which vary spatially, along with other obstructions (roots intrusion) and pipe deformations (pipe sags), may influence the detrimental buildup of FOG deposits. The purpose of this study was to quantify the spatial variation in FOG deposit formation and accumulation in a pilot-scale sewer collection system. The pilot system contained straight pipes, manholes, roots intrusion, and a pipe sag. Calcium and oil were injected into the system and operated at alkaline (pH = 10) and neutral (pH = 7) pH conditions. Results showed that solid accumulations were slightly higher at neutral pH. Fourier transform infrared (FTIR) analysis on the solids samples confirmed that the solids were indeed calcium-based fatty acid salts. However, the fatty acid profiles of the solids deviated from the profile found from FOG deposits in sewer systems, which were primarily saturated fatty acids. These results confirm the work done previously by researchers and suggest an alternative fate of unsaturated fatty acids that does not lead to their incorporation in FOG deposits in full-scale sewer systems.

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

    Science.gov (United States)

    2016-01-01

    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. PMID:27572244

  16. 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.

  17. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Tiren, Sven A.; Waenstedt, Stefan; Straeng, Thomas (GEOSIGMA AB (Sweden))

    2010-11-15

    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. Theoretical understanding on the v(1)-SO4(2-) band perturbed by the formation of magnesium sulfate ion pairs.

    Science.gov (United States)

    Zhang, Hao; Zhang, Yun-Hong; Wang, Feng

    2009-02-01

    The factors determining the spectroscopic characteristics of the v(1)-SO4(2-) band of the MgSO4 ion pairs are discussed via ab initio calculation, including coupling effect, hydrogen bonding effect, and direct contact effect of Mg2+ with SO4(2-). With the calculation of the heavy water hydrated contact ion pairs (CIP), the overlap between the librations of water and the v(1)-SO4(2-) band can be separated, and thus the coupling effect is abstracted, and this coupling effect leads to a blue shift for the v(1)-SO4(2-) band of 5.6 cm(-1) in the monodentate CIP and 3.6 cm(-1) in the bidentate CIP. The hydrogen bonding between each water molecule without relation to Mg2+ and the sulfate ion makes the v(1)-SO4(2-) band blue shift of 3.7 cm(-1). When the outer-sphere water around Mg2+ are hydrogen bonded between SO4(2-) and Mg2+, it will make the largest disturbance to the v(1)-SO4(2-) band. Moreover, the inner-sphere water can affect the v(1)-SO4(2-) band conjunct with the direct contact of Mg2+ with SO4(2-), showing a blue shift of 14.4 cm(-1) in the solvent-shared ion pair, 22.6 cm(-1) in the monodentate CIP, 4.3 cm(-1) in the bidentate CIP, and 21.4 cm(-1) in the tridentate CIP. At last, the Raman spectral evolution in the efflorescence production process is tried to be rationalized. The shoulder at 995 cm(-1) is attributed to the monodentate CIP with 2-3 outer-sphere water molecules, whereas the new peak at 1021 cm(-1) at high concentration is assigned to the formation of aqueous triple ion.

  20. 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

  1. From the teachers' eyes: An ethnographic-case study on developing models of Informal Formative Assessments (IFA) and understanding the challenges to effective implementation in science classrooms

    Science.gov (United States)

    Sezen, Asli

    The emphasis on socio-cultural theories of learning has required the understanding of multi-dimensional, dynamic and social nature of acquiring the scientific knowledge and practices. Recent policy documents suggest a focus on formative and dynamic assessment practices that will help understand and improve the complex nature of scientific learning in classrooms. This study focuses on teachers' use of "Informal Formative Assessments (IFA)" aimed at improving students' learning and teachers' frequent recognition of students' learning process. The study was designed as an ethnographic case study of four middle school teachers and their students at a local charter school. The data of the study included (a) teachers' responses to history of teaching questionnaire (b) video and audio records of teachers' assessment practices during two different scientific projects (c) video and audio records of ethnographic interviews with teachers during their reflections on their practices, and (d) field notes taken by the researcher to understand the assessment culture of the school. The analytical tools from sociolinguistics (e.g., transcripts and event maps) were prepared and discourse analysis based in an ethnographic perspective was used to analyze the data. Moreover, Cultural-Historical Activity Theory (CHAT) was also introduced as an alternative data analysis framework for understanding the role of division of labor among the elements of the community on the challenges and the outcomes of IFA practices. The findings from the analysis of the classroom discourse showed three different types of IFA cycles: connected, non-connected, and repeating. The analysis of the teachers' reflections showed that the effectiveness of these cycles did not only depend on whether the cycles were connected, but also on other variables such as the phase of the lessons and student's identities and abilities. Teachers' reflections during researcher-teacher meetings on the concept and the aims of IFA

  2. 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.

  3. Understanding the role of the cytoskeleton in wood formation in angiosperm trees: hybrid aspen (Populus tremula x P. tremuloides) as a model species

    Energy Technology Data Exchange (ETDEWEB)

    Chaffey, N.; Barlow, P. [Bristol Univ., Dept. of Agricultural Sciences, Long Ashton, (United Kingdom); Sundberg, B. [Swedish Univ. of Agricultural Sciences, Dept. of Forest Genetics and Plant Physiology, Umea (Sweden)

    2002-03-01

    The involvement of microfilaments (MFs) and microtubules (MTs) in the development of the radial and axial components of secondary wood in hybrid aspen (Populus tremula X P. tremuloides) was studied by indirect immunofluorescent localization techniques in order to elucidate a consensus view of the roles of the cytoskeleton during wood formation in angiosperm trees. Early and late vessel elements, axial parenchyma, normal-wood fibres and contact and isolation cells were included in addition to cambial cells. Microfilaments were found to be rare in cambial cells, but were abundant and axially arranged in their derivatives once cell elongation begun. Microtubules were randomly oriented in ray and fusiform cells of the cambial zone. Ellipses of microfilaments were associated with pit development in fiber cells and isolation ray cells. Rings of localized microtubules and microfilaments were associated with developing inter-vessel bordered pits and vessel-contact ray cell contact pits. Although only microtubules were seen in the periphery of the perforation plate of vessel elements, a prominent meshwork of microfilaments overlaid the perforation plate itself. These observations indicate that there are corresponding subcellular control points whose manipulation could lead to the development of 'designer wood'. However, such development would require a better understanding of the physiological basis for the behaviour of microtubule and microfibre cytoskeletons during wood formation. 44 refs., 6 figs.

  4. 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.

  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. Modern limnology, sediment accumulation and varve formation processes in Lake Żabińskie, northeastern Poland: comprehensive process studies as a key to understand the sediment record

    Directory of Open Access Journals (Sweden)

    Alicja Bonk

    2014-12-01

    Full Text Available Reconstructions of paleoclimatic and paleoenvironmental data from sediment records require a thorough knowledge of the physical, chemical and biological factors that influence sediment-formation processes and signal preservation in lake sediments. Lake Żabińskie, an eutrophic hardwater lake located in northeastern Poland (Masurian Lake District, provides an unique environment for the investigation of processes that lead to the varve formation. During a two-year long observation period we investigated limnological and hydrochemical conditions within the water column, recent sediment fluxes and laminations preserved in the sediments of this lake to understand the relationship between the lake water properties and the sediment formation processes. We demonstrate that different mixing patterns may occur in Lake Żabińskie, from dimictic to meromictic depending on the meteorological conditions. Regardless of the water mixing pattern, the lake was stratified during much of the year which led to significant differences between surface and near-bottom water environments. The hypolimnion was characterized by higher conductivity and anoxic conditions with only short periods of better oxygenation, which created conditions ideal for the formation and preservation of biogenic varves. The material collected from the sediment trap revealed notable changes in sediment fluxes with characteristic spring maxima and, optionally, a second late fall maxima. Considerable variability was also observed for the fluxes of total organic carbon, biogenic silica and calcite. Microscopic investigation of the topmost sediments revealed a complex structure of the varves showing a distinct spring calcite lamina followed by several fine calcite laminae interbedded with diatom-rich laminae and, finally, by an organic-rich lamina with minerogenic admixtures deposited during winter. This seasonal variability was also reflected in the chemical composition inferred from high

  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. Galaxy formation

    International Nuclear Information System (INIS)

    Silk, J.; Di Cintio, A.; Dvorkin, I.

    2014-01-01

    Galaxy formation is at the forefront of observation and theory in cosmology. An improved understanding is essential for improving our knowledge both of the cosmological parameters, of the contents of the universe, and of our origins. In these lectures intended for graduate students, galaxy formation theory is reviewed and confronted with recent observational issues. In lecture 1, the following topics are presented: star formation considerations, including IMF, star formation efficiency and star formation rate, the origin of the galaxy luminosity function, and feedback in dwarf galaxies. In lecture 2, we describe formation of disks and massive spheroids, including the growth of supermassive black holes, negative feedback in spheroids, the AGN-star formation connection, star formation rates at high redshift and the baryon fraction in galaxies.

  9. Understanding Electrically Active Interface Formation on Wide Bandgap Semiconductors through Molecular Beam Epitaxy Using Fe3O 4 for Spintronics as a Base Case

    Science.gov (United States)

    Hamedani Golshan, Negar

    Nanoelectronics, complex heterostructures, and engineered 3D matrix materials are quickly advancing from research possibilities to manufacturing challenges for applications ranging from high-power devices to solar cells to any number of novel multifunctional sensors and controllers. Formation of an abrupt and effective interface is one of the basic requirements for integration of functional materials on different types of semiconductors (from silicon to the wide bandgaps) which can significantly impact the functionality of nanoscale electronic devices. To realize the potential of next-generation electronics, the understanding and control of those initial stages of film layer formation must be understood and translated to a process that can control the initial stages of film deposition. Thin film Fe3O4 has attracted much attention as a material for exploring the potential of spintronics in next-generation information technologies. Synthesis of highly spin-polarized material as spin sources, in combination with wide bandgap semiconductors which have a long spin relaxation time in addition to functionality in high-temperature, high-power, and high-frequency environments, would enhance the performance of today's spintronic devices. Spinel ferrite Fe3O4 has a high Curie temperature of 858 K and it is predicted to possess half-metallic properties, i.e. 100% spin polarization at the Fermi level, which can lead to ultrahigh tunneling magnetoresistance at room temperature. However, these properties have been very difficult to realize in thin film form, and device design strategies require high-quality thin films of Fe3O4. The most common reason reported in literature for the failure of the films to achieve theoretical performance is that the growth techniques used today produce films with antiphase boundaries (APB). These APBs have a strong antiferromagnetic coupling that negatively impact the magnetic and transport properties of epitaxial Fe 3O4 films. Therefore, greater

  10. 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

  11. 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...

  12. 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.

  13. [Homeostasis and Disorder of Musculoskeletal System.Enthesis formation and repair:Current understanding and perspectives for the future regenerative therapy.

    Science.gov (United States)

    Tokunaga, Takuya; Arimura, Hitoshi; Mizuta, Hiroshi; Hiraki, Yuji; Shukunami, Chisa

    Tendons and ligaments are dense fibrous connective tissues mainly composed of type I collagen, aligned in highly ordered arrays along the axis of the tendon and ligament. The enthesis is defined as the attachment site of a tendon, ligament, joint capsule, or fascia to bone. During morphogenesis, the cell population co-expressing Scleraxis(Scx)and the SRY-box containing gene 9(Sox9)contributes to the formation of fibrocartilaginous entheses. Scx regulates tendon and ligament maturation, while Sox9 is a key regulatory factor for cartilage formation. The considerable mechanical forces transmitted through the enthesis and avascular properties of the tissue make it more prone to injuries and degenerative changes. Thus, integration of tendons or ligaments with bone following surgical repair remains a clinical challenge. In this review, we summarize the current knowledge regarding the formation, maintenance, damage, and repair of fibrocartilaginous entheses, focusing on the rotator cuff tendon-to-bone attachment sites.

  14. Using Clumped Isotopes to Understand Early Diagenetic Processes in Carbonate Microbialites of Mid-Cretaceous Codó Formation, NE Brazil

    Science.gov (United States)

    Bahniuk, A. M.; Vasconcelos, C.; McKenzie, J. A.; Franca, A. B.; Matsuda, N.; Eiler, J.

    2010-12-01

    Recent studies of the sedimentological, stratigraphic and geochemical aspects of carbonate microbialites have been carried out to characterize the paleoenvironmental and hydrological conditions of deposition for the Aptian Codó Formation (Parnaíba Basin) and the time-equivalent Santana Formation (Araripe Basin). This environmental interpretation is of interest because these sediments record the early stages of the opening of the Equatorial Atlantic Ocean, as well as being potentially important reservoir rock. Specifically, clumped isotope thermometry has been applied to evaluate the growth temperatures of carbonate components in selected samples from both outcrop and drill core. Preliminary results of clumped isotope measurements provide paleotemperatures derived for dense stromatolitic fabrics drilled from outcrop samples of the Codó Formation which vary between 29 and 33°C. In contrast, the micritic matrix of the drill core samples of the Codó Formation indicates a temperature range from 30 to 48°C. The lower values for the outcrop samples may represent a primary or early diagenetic temperature signal preserved in the rock. Moreover, the micritic matrix from the Santana Formation drill core samples indicates paleotemperatures ranging from 40 to 68°C, which are slightly higher than those for all measured samples of the Codó Formation. We propose that the higher paleotemperatures for all drill core samples denote a diagenetic effect that occurred with sediment lithification processes during burial; that is, isotopic reequilibration at depth is reflected in the higher measured paleotemperatures. Increased paleotemperatures are probably present in some carbonate fabrics of the outcrop samples of the Codo Formation, which also underwent lithification, but this signal was missed by our inability to micro-sample primary or early diagenetic stromatolitic fabrics. Assuming that the outcrop samples of the Codó Formation preserve an original stable isotope signal

  15. 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

  16. 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.

  17. Formational Turning Points in the Transition to College: Understanding How Communication Events Shape First-Generation Students' Pedagogical and Interpersonal Relationships with Their College Teachers

    Science.gov (United States)

    Wang, Tiffany R.

    2014-01-01

    In the present study, I explored student-teacher interaction, student-teacher relationship formation and development, and the ways in which student-teacher interaction and relationships facilitated support and persistence for first-generation (FG) students during the transition to college. Using transition theory as a sensitizing framework, I took…

  18. 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

  19. 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

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

    International Nuclear Information System (INIS)

    Mercier, D.; Rouchaud, J.-C.; Barthes-Labrousse, M.-G.

    2008-01-01

    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 x O y H 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 x O y H z ...N bond. Al-OH...N and C x O y H 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 η 1 -OH and bridged μ 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

  1. Understanding the formation and growth of Ag nanoparticles on silver chromate induced by electron irradiation in electron microscope: A combined experimental and theoretical study

    International Nuclear Information System (INIS)

    Fabbro, Maria T.; Gracia, Lourdes; Silva, Gabriela S.; Santos, Luís P.S.; Andrés, Juan; Cordoncillo, Eloisa; Longo, E.

    2016-01-01

    Ag 2 CrO 4 microcrystals were synthesized using the co-precipitation method. These microcrystals were characterized through X-ray diffraction (XRD) with Rietveld analysis, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) with energy-dispersive spectroscopy (EDS), micro-Raman (MR). XRD patterns and Rietveld refinement data showed that the material exhibits an orthorhombic structure without any deleterious phases. FE-SEM and TEM micrographs revealed the morphology and the growth of Ag nanoparticles on Ag 2 CrO 4 microcrystals during electron beam irradiation. These events were directly monitored in real-time. Their optical properties were investigated using ultraviolet-visible (UV–vis) diffuse reflectance spectroscopy that allowed the calculation of the optical band gap energy. Theoretical analyses based on the density functional theory level indicate that the incorporation of electrons is responsible for structural modifications and formation of defects on the [AgO 6 ] and [AgO 4 ] clusters, generating ideal conditions for the growth of Ag nanoparticles. - Graphical abstract: Theoretical representation of the Ag 2 CrO 4 orthorhombic structure. Display Omitted - Highlights: • The Ag 2 CrO 4 microcrystals indicate an orthorhombic structure. • The formation of Ag 0 promotes Ag-nanoparticle growth on the surface of the Ag 2 CrO 4 . • Electron irradiation of the material induces the formation of Ag vacancies.

  2. 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

  3. Public comment sentiment on educational videos: Understanding the effects of presenter gender, video format, threading, and moderation on YouTube TED talk comments.

    Directory of Open Access Journals (Sweden)

    George Veletsianos

    Full Text Available Scholars, educators, and students are increasingly encouraged to participate in online spaces. While the current literature highlights the potential positive outcomes of such participation, little research exists on the sentiment that these individuals may face online and on the factors that may lead some people to face different types of sentiment than others. To investigate these issues, we examined the strength of positive and negative sentiment expressed in response to TEDx and TED-Ed talks posted on YouTube (n = 655, the effect of several variables on comment and reply sentiment (n = 774,939, and the projected effects that sentiment-based moderation would have had on posted content. We found that most comments and replies were neutral in nature and some topics were more likely than others to elicit positive or negative sentiment. Videos of male presenters showed greater neutrality, while videos of female presenters saw significantly greater positive and negative polarity in replies. Animations neutralized both the negativity and positivity of replies at a very high rate. Gender and video format influenced the sentiment of replies and not just the initial comments that were directed toward the video. Finally, we found that using sentiment as a way to moderate offensive content would have a significant effect on non-offensive content. These findings have far-reaching implications for social media platforms and for those who encourage or prepare students and scholars to participate online.

  4. Public comment sentiment on educational videos: Understanding the effects of presenter gender, video format, threading, and moderation on YouTube TED talk comments

    Science.gov (United States)

    Kimmons, Royce; Larsen, Ross; Dousay, Tonia A.; Lowenthal, Patrick R.

    2018-01-01

    Scholars, educators, and students are increasingly encouraged to participate in online spaces. While the current literature highlights the potential positive outcomes of such participation, little research exists on the sentiment that these individuals may face online and on the factors that may lead some people to face different types of sentiment than others. To investigate these issues, we examined the strength of positive and negative sentiment expressed in response to TEDx and TED-Ed talks posted on YouTube (n = 655), the effect of several variables on comment and reply sentiment (n = 774,939), and the projected effects that sentiment-based moderation would have had on posted content. We found that most comments and replies were neutral in nature and some topics were more likely than others to elicit positive or negative sentiment. Videos of male presenters showed greater neutrality, while videos of female presenters saw significantly greater positive and negative polarity in replies. Animations neutralized both the negativity and positivity of replies at a very high rate. Gender and video format influenced the sentiment of replies and not just the initial comments that were directed toward the video. Finally, we found that using sentiment as a way to moderate offensive content would have a significant effect on non-offensive content. These findings have far-reaching implications for social media platforms and for those who encourage or prepare students and scholars to participate online. PMID:29856749

  5. Towards understanding the role of amines in the SO2 hydration and the contribution of the hydrated product to new particle formation in the Earth's atmosphere.

    Science.gov (United States)

    Lv, Guochun; Nadykto, Alexey B; Sun, Xiaomin; Zhang, Chenxi; Xu, Yisheng

    2018-08-01

    By theoretical calculations, the gas-phase SO 2 hydration reaction assisted by methylamine (MA) and dimethylamine (DMA) was investigated, and the potential contribution of the hydrated product to new particle formation (NPF) also was evaluated. The results show that the energy barrier for aliphatic amines (MA and DMA) assisted SO 2 hydration reaction is lower than the corresponding that of water and ammonia assisted SO 2 hydration. In these hydration reactions, nearly barrierless reaction (only a barrier of 0.1 kcal mol -1 ) can be found in the case of SO 2  + 2H 2 O + DMA. These lead us to conclude that the SO 2 hydration reaction assisted by MA and DMA is energetically facile. The temporal evolution for hydrated products (CH 3 NH 3 + -HSO 3 - -H 2 O or (CH 3 ) 2 NH 2 + -HSO 3 - -H 2 O) in molecular dynamics simulations indicates that these complexes can self-aggregate into bigger clusters and can absorb water and amine molecules, which means that these hydrated products formed by the hydration reaction may serve as a condensation nucleus to initiate the NPF. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Public comment sentiment on educational videos: Understanding the effects of presenter gender, video format, threading, and moderation on YouTube TED talk comments.

    Science.gov (United States)

    Veletsianos, George; Kimmons, Royce; Larsen, Ross; Dousay, Tonia A; Lowenthal, Patrick R

    2018-01-01

    Scholars, educators, and students are increasingly encouraged to participate in online spaces. While the current literature highlights the potential positive outcomes of such participation, little research exists on the sentiment that these individuals may face online and on the factors that may lead some people to face different types of sentiment than others. To investigate these issues, we examined the strength of positive and negative sentiment expressed in response to TEDx and TED-Ed talks posted on YouTube (n = 655), the effect of several variables on comment and reply sentiment (n = 774,939), and the projected effects that sentiment-based moderation would have had on posted content. We found that most comments and replies were neutral in nature and some topics were more likely than others to elicit positive or negative sentiment. Videos of male presenters showed greater neutrality, while videos of female presenters saw significantly greater positive and negative polarity in replies. Animations neutralized both the negativity and positivity of replies at a very high rate. Gender and video format influenced the sentiment of replies and not just the initial comments that were directed toward the video. Finally, we found that using sentiment as a way to moderate offensive content would have a significant effect on non-offensive content. These findings have far-reaching implications for social media platforms and for those who encourage or prepare students and scholars to participate online.

  7. Solid Phases Precipitating in Artificial Urine in the Absence and Presence of Bacteria Proteus mirabilis—A Contribution to the Understanding of Infectious Urinary Stone Formation

    Directory of Open Access Journals (Sweden)

    Jolanta Prywer

    2018-04-01

    Full Text Available Magnesium ammonium phosphate hexahydrate, called struvite, is the dominant component of infectious urinary stones. In addition to struvite, infectious urinary stones include solid phases with poor crystallinity as well as amorphous matter. This article is devoted to the analysis of these solid phases, because they have not been characterized well until now. The solid phases tested were obtained from artificial urine in the absence and presence of Proteus mirabilis. The solid phases were characterized by different techniques (X-ray Diffraction, Energy Dispersive X-ray, Scanning Electron Microscopy, as well as Raman and Infrared Spectroscopies. According to the results these phases are carbonate apatite (CA, hydroxylapatite (HAP, amorphous calcium carbonate (ACC, amorphous calcium phosphate (ACP and/or amorphous carbonated calcium phosphate (ACCP. Carbonate apatite and hydroxylapatite may occur in non-stoichiometric forms, i.e., various anions can be substituted for CO32−, OH−, and PO43− groups in them. The non-stoichiometry of carbonate apatite and hydroxylapatite also implies a deficiency of calcium ions, i.e., calcium ions may be partially replaced by other cations. Experimental techniques and chemical speciation analysis demonstrate that the presence of magnesium influences the formation of CA and HAP.

  8. Understanding the role of the cytoskeleton in wood formation in angiosperm trees: hybrid aspen (Populus tremula x P. tremuloides) as the model species.

    Science.gov (United States)

    Chaffey, Nigel; Barlow, Peter; Sundberg, Björn

    2002-03-01

    The involvement of microfilaments and microtubules in the development of the radial and axial components of secondary xylem (wood) in hybrid aspen (Populus tremula L. x P. tremuloides Michx.) was studied by indirect immunofluorescent localization techniques. In addition to cambial cells, the differentiated cell types considered were early- and late-wood vessel elements, axial parenchyma, normal-wood fibers and gelatinous fibers, and contact and isolation ray cells. Microfilaments were rare in ray cambial cells, but were abundant and axially arranged in their derivatives once cell elongation had begun, and persisted in that orientation in mature ray cells. Microfilaments were axially arranged in fusiform cambial cells and persisted in that orientation in all xylem derivatives of those cells. Microtubules were randomly oriented in ray and fusiform cells of the cambial zone. Dense arrays of parallel-aligned microtubules were oriented near axially in the developing gelatinous fibers, but at a wide range of angles in normal-wood fibers. Ellipses of microfilaments were associated with pit development in fiber cells and isolation ray cells. Rings of co-localized microtubules and microfilaments were associated with developing inter-vessel bordered pits and vessel-contact ray cell contact pits, and, in the case of bordered pits, these rings decreased in diameter as the over-arching pit border increased in size. Although only microtubules were seen at the periphery of the perforation plate of vessel elements, a prominent meshwork of microfilaments overlaid the perforation plate itself. A consensus view of the roles of the cytoskeleton during wood formation in angiosperm trees is presented.

  9. 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

  10. Calibration of the seismic velocity structure and understanding of the fault formation in the environs of the Orkney M5.5 earthquake, South Africa

    Science.gov (United States)

    Ogasawara, H.; Manzi, M. S.; Durrheim, R. J.; Ogasawara, H.

    2017-12-01

    In August 2014, the largest seismic event (M5.5) to occur in a South African gold mining district took place near Orkney. The M5.5 event and aftershocks were recorded by strainmeters installed at 3 km depth hundreds of meters above the M5.5 fault, 46 in-mine 4.5Hz triaxial geophone stations at depths of 2-3 km within a hypocentral radius of 2-3 km, and 17 surface strong motion stations (South African Seismograph Network; SANSN) within an epicentral radius of 25 km. Aftershocks were distributed on a nearly vertical plane striking NNW-SSE. The upper edge of this fault was hundreds of meters below the deepest level of the mine. ICDP approved a project "Drilling into seismogenic zones of M2.0-5.5 earthquakes in South African gold mines" to elucidate the details of the events (DSeis; Yabe et al. invited talk in S020 in this AGU). On 1 August 2017 drilling was within a few hundreds of meters of intersecting the M5.5 fault zone. To locate the drilling target accurately it is very important to determine the velocity structure between the seismic events and sensors. We do this by using the interval velocities used to migrate 3D-reflection seismic data that was previously acquired by a mining company to image the gold-bearing reef and any fault structures close to the mining horizon. Less attention was given to the velocities below the mining horizon, as accurate imaging of the geological structure was not as important and very little drilling information was available. We used the known depths of prominent reflectors above the mining horizon to derive the interval velocities needed to convert two-way-travel-time to depth. We constrain the velocity below the mining horizon by comparing the DSeis drilling results with the 3D seismic cube. The geometric data is crucial for the kinematic modeling that Ogasawara et al. (S018 in this AGU) advocates. The efforts will result in a better understanding of the main rupture and aftershocks.

  11. Profile Septa cut out condensate crud

    International Nuclear Information System (INIS)

    Poschmann, T.

    1991-01-01

    Secondary side corrosion is a major factor leading to steam generator tube plugging. Large quantities of steam generator sludge can harden, prolonging system maintenance during an outage. However, eliminating the ingress of solids to the PWR steam generators can reduce the need for sludge lancing and increase the life of the steam generator tubes. The Pall Corporation has developed an improved filter demineralizer septum for retrofitting traditional yarn-wound elements without having to modify hardware. In November 1990, operators at Turkey Point installed 496 2in x 70in Pall's Profile Septa in one of the four filter demineralizer vessels on unit 3. After installation of the Profile Septa, samples of filter influent and effluent were taken and analyzed over a one-month period - these showed a particulate removal rate of 96-99%. Contaminant analysis by Pall Corporation identified the vast majority of particulates to be iron oxides. This is as was expected, since Turkey Point has titanium condenser tubes which reduce the source of copper oxides. The success of Profile Septa at Turkey Point has encouraged the other utilities to look at using the septa at their own plants. The cost for these retrofits would be recouped through savings in maintenance costs, due to faster steam generator lancing (fewer solids), reduced radiation exposure and, ultimately, longer steam generator life. (author)

  12. 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...

  13. Habit formation.

    Science.gov (United States)

    Smith, Kyle S; Graybiel, Ann M

    2016-03-01

    Habits, both good ones and bad ones, are pervasive in animal behavior. Important frameworks have been developed to understand habits through psychological and neurobiological studies. This work has given us a rich understanding of brain networks that promote habits, and has also helped us to understand what constitutes a habitual behavior as opposed to a behavior that is more flexible and prospective. Mounting evidence from studies using neural recording methods suggests that habit formation is not a simple process. We review this evidence and take the position that habits could be sculpted from multiple dissociable changes in neural activity. These changes occur across multiple brain regions and even within single brain regions. This strategy of classifying components of a habit based on different brain signals provides a potentially useful new way to conceive of disorders that involve overly fixed behaviors as arising from different potential dysfunctions within the brain's habit network.

  14. Habit formation

    Science.gov (United States)

    Smith, Kyle S.; Graybiel, Ann M.

    2016-01-01

    Habits, both good ones and bad ones, are pervasive in animal behavior. Important frameworks have been developed to understand habits through psychological and neurobiological studies. This work has given us a rich understanding of brain networks that promote habits, and has also helped us to understand what constitutes a habitual behavior as opposed to a behavior that is more flexible and prospective. Mounting evidence from studies using neural recording methods suggests that habit formation is not a simple process. We review this evidence and take the position that habits could be sculpted from multiple dissociable changes in neural activity. These changes occur across multiple brain regions and even within single brain regions. This strategy of classifying components of a habit based on different brain signals provides a potentially useful new way to conceive of disorders that involve overly fixed behaviors as arising from different potential dysfunctions within the brain's habit network. PMID:27069378

  15. Comet formation

    Science.gov (United States)

    Blum, J.

    2014-07-01

    There has been vast progress in our understanding of planetesimal formation over the past decades, owing to a number of laboratory experiments as well as to refined models of dust and ice agglomeration in protoplanetary disks. Coagulation rapidly forms cm-sized ''pebbles'' by direct sticking in collisions at low velocities (Güttler et al. 2010; Zsom et al. 2010). For the further growth, two model approaches are currently being discussed: (1) Local concentration of pebbles in nebular instabilities until gravitational instability occurs (Johansen et al. 2007). (2) A competition between fragmentation and mass transfer in collisions among the dusty bodies, in which a few ''lucky winners'' make it to planetesimal sizes (Windmark et al. 2012a,b; Garaud et al. 2013). Predictions of the physical properties of the resulting bodies in both models allow a distinction of the two formation scenarios of planetesimals. In particular, the tensile strength (i.e, the inner cohesion) of the planetesimals differ widely between the two models (Skorov & Blum 2012; Blum et al. 2014). While model (1) predicts tensile strengths on the order of ˜ 1 Pa, model (2) results in rather compactified dusty bodies with tensile strengths in the kPa regime. If comets are km-sized survivors of the planetesimal-formation era, they should in principle hold the secret of their formation process. Water ice is the prime volatile responsible for the activity of comets. Thermophysical models of the heat and mass transport close to the comet-nucleus surface predict water-ice sublimation temperatures that relate to maximum sublimation pressures well below the kPa regime predicted for formation scenario (2). Model (1), however, is in agreement with the observed dust and gas activity of comets. Thus, a formation scenario for cometesimals involving gravitational instability is favored (Blum et al. 2014).

  16. Radionuclide migration in clayrock host formations for deep geological disposal of radioactive waste: advances in process understanding and up-scaling methods resulting from the EC integrated project `Funmig

    Science.gov (United States)

    Altmann, S.; Tournassat, C.; Goutelard, F.; Parneix, J. C.; Gimmi, T.; Maes, N.

    2009-04-01

    One of the ‘pillars' supporting Safety Cases for deep geological disposal of radioactive waste in clayrock formations is the knowledge base regarding radionuclide (Rn) retention by sorption and diffusion-driven transport which is why the EC integrated project ‘Funmig' focused a major part of its effort on advancing understanding of these two macroscopic phenomena. This talk presents some of the main results of this four year effort (2005-2008). One of the keys to understanding diffusion-driven transport of anionic and cationic radionuclide species in clayrocks lies in a detailed understanding of the phenomena governing Rn total concentration and speciation (dissolved, adsorbed) in the different types of pore spaces present in highly-compacted masses of permanently charged clay minerals. Work carried out on a specifically synthesized montmorillonite (a model for the clay mineral fraction in clayrocks) led to development, and preliminary experimental validation, of a conceptually coherent set of theoretical models (molecular dynamics, electrostatic double layer, thermodynamic) describing dissolved ion and water solvent behavior in this material. This work, complemented by the existing state of the art, provides a sound theoretical basis for explaining such important phenomena as anion exclusion, cation exchange and the diffusion behavior of anions, weakly sorbing cations and water tracers. Concerning the behavior of strongly sorbing and/or redox-reactive radionuclides in clay systems, project research improved understanding of the nature of sorption reactions and sorbed species structure for key radioelements, or analogues (U, Se, Eu, Sm, Yb, Nd) on the basal surfaces and in the interlayers of synthetic or purified clay minerals. A probable mechanism for Se(IV) retention by reduction to Se° in Fe2+-containing clays was brought to light; this same process was also studied on the Callovo-Oxfordien clayrock targeted by the French radwaste management program. The

  17. Understanding the effects of potassium ferricyanide on lead hydride formation in tetrahydroborate system and its application for determination of lead in milk using hydride generation inductively coupled plasma optical emission spectrometry

    International Nuclear Information System (INIS)

    Deng, Biyang; Xu, Xiangshu; Xiao, Yan; Zhu, Pingchuan; Wang, Yingzi

    2015-01-01

    Highlights: • Proposed a novel explanation for plumbane generation. • Expounded the role of K 3 Fe(CN) 6 in plumbane generation. • Clarified the controversial aspects in the mechanism of K 3 Fe(CN) 6 enhancement. • Used X-ray diffractometry to analyze the intermediates. • Developed a method to analyze lead in milk using K 3 Fe(CN) 6 and K 4 Fe(CN) 6 as new additives. - Absract: To understand the formation of plumbane in the Pb II -NaBH 4 -K 3 Fe(CN) 6 system, the intermediate products produced in the reaction of lead(II) and NaBH 4 in the presence of K 3 Fe(CN) 6 were studied. The produced plumbane and elemental lead were measured through continuous flow hydride generation (HG)-inductively coupled plasma optical emission spectrometry (ICP OES) and X-ray diffraction spectrometry techniques, respectively. Based on the experimental results, the explanations can be depicted in the following steps: (1) plumbane and black lead sediment (black Pb) are formed in the reaction of lead(II) and NaBH 4 ; (2) the black Pb is oxidized by K 3 Fe(CN) 6 to form Pb 2 [Fe(CN) 6 ], which further reacts with NaBH 4 to form more plumbane and black Pb; and (3) another round starts in which the produced black Pb from the step 2 is then oxidized continuously by K 3 Fe(CN) 6 to form more Pb 2 [Fe(CN) 6 ] complex, which would produce more plumbane. In short, the black Pb and Pb 2 [Fe(CN) 6 ] complex are the key intermediate products for the formation of plumbane in the Pb II -NaBH 4 -K 3 Fe(CN) 6 system. Based on the enhancement effect of potassium ferricyanide and potassium ferrocyanide, a method was developed to analyze lead in milk with HG-ICP OES technique. The detection limit of the method was observed as 0.081 μg L −1 . The linearity range of lead was found between 0.3 and 50,000 μg L −1 with correlation coefficient of 0.9993. The recovery of lead was determined as 97.6% (n = 5) for adding 10 μg L −1 lead into the milk sample

  18. 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 ...

  19. 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.

  20. Embodied Understanding

    Directory of Open Access Journals (Sweden)

    Mark Leonard Johnson

    2015-06-01

    Full Text Available 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.

  1. 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.

  2. 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

  3. Understanding Federalism.

    Science.gov (United States)

    Hickok, Eugene W., Jr.

    1990-01-01

    Urges returning to the original federalist debates to understand contemporary federalism. Reviews "The Federalist Papers," how federalism has evolved, and the centralization of the national government through acts of Congress and Supreme Court decisions. Recommends teaching about federalism as part of teaching about U.S. government…

  4. 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…

  5. Understanding the effects of potassium ferricyanide on lead hydride formation in tetrahydroborate system and its application for determination of lead in milk using hydride generation inductively coupled plasma optical emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Biyang, E-mail: dengby16@163.com; Xu, Xiangshu; Xiao, Yan; Zhu, Pingchuan; Wang, Yingzi

    2015-01-01

    Highlights: • Proposed a novel explanation for plumbane generation. • Expounded the role of K{sub 3}Fe(CN){sub 6} in plumbane generation. • Clarified the controversial aspects in the mechanism of K{sub 3}Fe(CN){sub 6} enhancement. • Used X-ray diffractometry to analyze the intermediates. • Developed a method to analyze lead in milk using K{sub 3}Fe(CN){sub 6} and K{sub 4}Fe(CN){sub 6} as new additives. - Absract: To understand the formation of plumbane in the Pb{sup II}-NaBH{sub 4}-K{sub 3}Fe(CN){sub 6} system, the intermediate products produced in the reaction of lead(II) and NaBH{sub 4} in the presence of K{sub 3}Fe(CN){sub 6} were studied. The produced plumbane and elemental lead were measured through continuous flow hydride generation (HG)-inductively coupled plasma optical emission spectrometry (ICP OES) and X-ray diffraction spectrometry techniques, respectively. Based on the experimental results, the explanations can be depicted in the following steps: (1) plumbane and black lead sediment (black Pb) are formed in the reaction of lead(II) and NaBH{sub 4}; (2) the black Pb is oxidized by K{sub 3}Fe(CN){sub 6} to form Pb{sub 2}[Fe(CN){sub 6}], which further reacts with NaBH{sub 4} to form more plumbane and black Pb; and (3) another round starts in which the produced black Pb from the step 2 is then oxidized continuously by K{sub 3}Fe(CN){sub 6} to form more Pb{sub 2}[Fe(CN){sub 6}] complex, which would produce more plumbane. In short, the black Pb and Pb{sub 2}[Fe(CN){sub 6}] complex are the key intermediate products for the formation of plumbane in the Pb{sup II}-NaBH{sub 4}-K{sub 3}Fe(CN){sub 6} system. Based on the enhancement effect of potassium ferricyanide and potassium ferrocyanide, a method was developed to analyze lead in milk with HG-ICP OES technique. The detection limit of the method was observed as 0.081 μg L{sup −1}. The linearity range of lead was found between 0.3 and 50,000 μg L{sup −1} with correlation coefficient of 0

  6. 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....

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Understanding Magnitudes to Understand Fractions

    Science.gov (United States)

    Gabriel, Florence

    2016-01-01

    Fractions are known to be difficult to learn and difficult to teach, yet they are vital for students to have access to further mathematical concepts. This article uses evidence to support teachers employing teaching methods that focus on the conceptual understanding of the magnitude of fractions.

  12. Testing Understanding and Understanding Testing.

    Science.gov (United States)

    Pedersen, Jean; Ross, Peter

    1985-01-01

    Provides examples in which graphs are used in the statements of problems or in their solutions as a means of testing understanding of mathematical concepts. Examples (appropriate for a beginning course in calculus and analytic geometry) include slopes of lines and curves, quadratic formula, properties of the definite integral, and others. (JN)

  13. 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

  14. 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.

  15. 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...

  16. 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.

  17. 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.

  18. 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...

  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...... tested in library contexts and the aim of this article is to identify the main approaches and to discuss their perspectives, including their strenghts and weaknesses in, especially, public library contexts. The purpose is also to prsent and discuss the results of a recent - 2014 - Danish library user...... 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 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

  1. Understanding signal integrity

    CERN Document Server

    Thierauf, Stephen C

    2010-01-01

    This unique book provides you with practical guidance on understanding and interpreting signal integrity (SI) performance to help you with your challenging circuit board design projects. You find high-level discussions of important SI concepts presented in a clear and easily accessible format, including question and answer sections and bulleted lists.This valuable resource features rules of thumb and simple equations to help you make estimates of critical signal integrity parameters without using circuit simulators of CAD (computer-aided design). The book is supported with over 120 illustratio

  2. Formative (measurement)

    NARCIS (Netherlands)

    Fassott, G.; Henseler, Jörg; Cooper, C.; Lee, N.; Farrell, A.

    2015-01-01

    When using measurement models with multiple indicators, researchers need to decide about the epistemic relationship between the latent variable and its indicators. In this article, we describe the nature, the estimation, the characteristics, and the validity assessment of formative measurement

  3. Vascular lumen formation.

    Science.gov (United States)

    Lammert, Eckhard; Axnick, Jennifer

    2012-04-01

    The vascular system developed early in evolution. It is required in large multicellular organisms for the transport of nutrients, oxygen, and waste products to and from tissues. The vascular system is composed of hollow tubes, which have a high level of complexity in vertebrates. Vasculogenesis describes the de novo formation of blood vessels, e.g., aorta formation in vertebrate embryogenesis. In contrast, angiogenesis is the formation of blood vessels from preexisting ones, e.g., sprouting of intersomitic blood vessels from the aorta. Importantly, the lumen of all blood vessels in vertebrates is lined and formed by endothelial cells. In both vasculogenesis and angiogenesis, lumen formation takes place in a cord of endothelial cells. It involves a complex molecular mechanism composed of endothelial cell repulsion at the cell-cell contacts within the endothelial cell cords, junctional rearrangement, and endothelial cell shape change. As the vascular system also participates in the course of many diseases, such as cancer, stroke, and myocardial infarction, it is important to understand and make use of the molecular mechanisms of blood vessel formation to better understand and manipulate the pathomechanisms involved.

  4. 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......−liquid reactions are discussed, as are the influences of particles sizes on clinker phase formation. Furthermore, a mechanism for clinker phase formation in an industrial rotary kiln reactor is outlined....

  5. 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

  6. 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...

  7. 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.

    Science.gov (United States)

    Maulik, Pallab K; Tewari, Abha; Devarapalli, Siddhardha; Kallakuri, Sudha; Patel, Anushka

    2016-01-01

    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.

  8. 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.

  9. Utilization of circular dichroism and electrospray ionization mass spectrometry to understand the formation and conversion of G-quadruplex DNA at the human c-myb proto-oncogene.

    Science.gov (United States)

    Fu, Hengqing; Yang, Pengfei; Hai, Jinhui; Li, Huihui

    2018-10-05

    G-quadruplex DNAs are involved in a number of key biological processes, including gene expression, transcription, and apoptosis. The c-myb oncogene contains a number of GGA repeats in its promoter which forms G-quadruplex, thus it could be used as a target in cancer therapeutics. Several in-vitro studies have used Circular Dichroism (CD) spectroscopy or electrospray ionization mass spectrometry (ESI-MS) to demonstrate formation and stability of G-quadruplex DNA structure in the promoter region of human c-myb oncogene. The factors affecting the c-myb G-quadruplex structures were investigated, such as cations (i.e. K + , NH 4 + and Na + ) and co-solutes (methanol and polyethylene glycol). The results indicated that the presence of cations and co-solutes could change the G-quadruplex structural population and promote its thermodynamic stabilization as indicated by CD melting curves. It indicated that the co-solutes preferentially stabilize the c-myb G-quadruplex structure containing both homo- and hetero-stacking. In addition, protopine was demonstrated as a binder of c-myb G-quadruplex as screened from a library of natural alkaloids using ESI-MS method. CD spectra showed that it could selectively stabilize the c-myb G-quadruplex structure compared to other six G-quadruplexes from tumor-related G-rich sequences and the duplex DNAs (both long and short-chain ones). The binding of protopine could induce the change in the G-quadruplex structural populations. Therefore, protopine with its high binding specificity could be considered as a precursor for the design of drugs to target and regulate c-myb oncogene transcription. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. 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.

  11. 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...

  12. 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...

  13. 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.

  14. 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.    

  15. 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).

  16. environmental impacts of crud local government area ol impacts

    African Journals Online (AJOL)

    pc

    2017-06-01

    Jun 1, 2017 ... where oil is released into the ocean or coastal wate. Oil spills include ... L IMPACTS OF CRUDE OIL SPILLAGES ON WATER IN IBENO. OVERNMENT ..... therefore highly dangerous to drink from the water at. Upenekang ...

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

    African Journals Online (AJOL)

    pc

    2017-06-01

    Jun 1, 2017 ... environment due to human activities, and is a form pollution. The term .... declining fishery resources, ed the specific impact of oil es. One of such ... effects of oil spillage on water quality/ management in. Emadadja, Udu .... 97.9. 500. 7. Total dissolve solids(mg/L). 310. 285. 298. 277. 215. 210. 88.7. 500. 8.

  18. 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.

  19. 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.

  20. Planet Formation

    Science.gov (United States)

    Podolak, Morris

    2018-04-01

    Modern observational techniques are still not powerful enough to directly view planet formation, and so it is necessary to rely on theory. However, observations do give two important clues to the formation process. The first is that the most primitive form of material in interstellar space exists as a dilute gas. Some of this gas is unstable against gravitational collapse, and begins to contract. Because the angular momentum of the gas is not zero, it contracts along the spin axis, but remains extended in the plane perpendicular to that axis, so that a disk is formed. Viscous processes in the disk carry most of the mass into the center where a star eventually forms. In the process, almost as a by-product, a planetary system is formed as well. The second clue is the time required. Young stars are indeed observed to have gas disks, composed mostly of hydrogen and helium, surrounding them, and observations tell us that these disks dissipate after about 5 to 10 million years. If planets like Jupiter and Saturn, which are very rich in hydrogen and helium, are to form in such a disk, they must accrete their gas within 5 million years of the time of the formation of the disk. Any formation scenario one proposes must produce Jupiter in that time, although the terrestrial planets, which don't contain significant amounts of hydrogen and helium, could have taken longer to build. Modern estimates for the formation time of the Earth are of the order of 100 million years. To date there are two main candidate theories for producing Jupiter-like planets. The core accretion (CA) scenario supposes that any solid materials in the disk slowly coagulate into protoplanetary cores with progressively larger masses. If the core remains small enough it won't have a strong enough gravitational force to attract gas from the surrounding disk, and the result will be a terrestrial planet. If the core grows large enough (of the order of ten Earth masses), and the disk has not yet dissipated, then

  1. 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.

  2. Galaxy formation

    International Nuclear Information System (INIS)

    Gribbin, J.

    1979-01-01

    The current debate on the origin and evolution of galaxies is reviewed and evidence to support the so-called 'isothermal' and 'adiabatic' fluctuation models considered. It is shown that new theories have to explain the formation of both spiral and elliptical galaxies and the reason for their differences. It is stated that of the most recent models the best indicates that rotating spiral galaxies are formed naturally when gas concentrates in the centre of a great halo and forms stars while ellipticals are explained by later interactions between spiral galaxies and merging, which can cancel out the rotation while producing an elliptical galaxy in which the stars, coming from two original galaxies, follow very elliptical, anisotropic orbits. (UK)

  3. 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…

  4. 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.

  5. A comparative transcriptomic approach to understanding the formation of cork.

    Science.gov (United States)

    Boher, Pau; Soler, Marçal; Sánchez, Anna; Hoede, Claire; Noirot, Céline; Paiva, Jorge Almiro Pinto; Serra, Olga; Figueras, Mercè

    2018-01-01

    The transcriptome comparison of two oak species reveals possible candidates accounting for the exceptionally thick and pure cork oak phellem, such as those involved in secondary metabolism and phellogen activity. Cork oak, Quercus suber, differs from other Mediterranean oaks such as holm oak (Quercus ilex) by the thickness and organization of the external bark. While holm oak outer bark contains sequential periderms interspersed with dead secondary phloem (rhytidome), the cork oak outer bark only contains thick layers of phellem (cork rings) that accumulate until reaching a thickness that allows industrial uses. Here we compare the cork oak outer bark transcriptome with that of holm oak. Both transcriptomes present similitudes in their complexity, but whereas cork oak external bark is enriched with upregulated genes related to suberin, which is the main polymer responsible for the protective function of periderm, the upregulated categories of holm oak are enriched in abiotic stress and chromatin assembly. Concomitantly with the upregulation of suberin-related genes, there is also induction of regulatory and meristematic genes, whose predicted activities agree with the increased number of phellem layers found in the cork oak sample. Further transcript profiling among different cork oak tissues and conditions suggests that cork and wood share many regulatory mechanisms, probably reflecting similar ontogeny. Moreover, the analysis of transcripts accumulation during the cork growth season showed that most regulatory genes are upregulated early in the season when the cork cambium becomes active. Altogether our work provides the first transcriptome comparison between cork oak and holm oak outer bark, which unveils new regulatory candidate genes of phellem development.

  6. 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.

  7. Formation of planetary systems

    International Nuclear Information System (INIS)

    Brahic, A.

    1982-01-01

    It seemed appropriate to devote the 1980 School to the origin of the solar system and more particularly to the formation of planetary systems (dynamic accretion processes, small bodies, planetary rings, etc...) and to the physics and chemistry of planetary interiors, surface and atmospheres (physical and chemical constraints associated with their formation). This Summer School enabled both young researchers and hard-nosed scientists, gathered together in idyllic surroundings, to hold numerous discussions, to lay the foundations for future cooperation, to acquire an excellent basic understanding, and to make many useful contacts. This volume reflects the lectures and presentations that were delivered in this Summer School setting. It is aimed at both advanced students and research workers wishing to specialize in planetology. Every effort has been made to give an overview of the basic knowledge required in order to gain a better understanding of the origin of the solar system. Each article has been revised by one or two referees whom I would like to thank for their assistance. Between the end of the School in August 1980 and the publication of this volume in 1982, the Voyager probes have returned a wealth of useful information. Some preliminary results have been included for completeness

  8. UNDERSTANDING UNDERGRADUATE STUDENTS PRACTICUM ...

    African Journals Online (AJOL)

    User

    student misbehavior as the most stressful experience of student teacher practicum experience. ... adequate support, rethinking assessment mechanism, provision of adequate fund, strengthening ..... provide regular formative feedback, have.

  9. FORMATIVE ASSESSMENT IN EFL CLASSROOM PRACTICES

    Directory of Open Access Journals (Sweden)

    Ida Ayu Made Sri Widiastuti

    2017-03-01

    Full Text Available This study investigated the challenges and opportunities of formative assessment in EFL classes. It made use of qualitative research design by using indepth interviews to collect the required data. Three teachers and three students were involved as research participants in this study and they were intensively interviewed to get valid and reliable data regarding their understanding of formative assessment and the follow up actions they took after implementing formative assessment. The results of this study showed that the English teachers were found not to take appropriate follow up actions due to their low understanding of formative assessment. The teachers’ understanding could influence their ability in deciding the actions. This study indicates that EFL teachers need urgent further intensive training on the appropriate implementation of formative assessment and how follow up actions should be integrated into classroom practices

  10. 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.

  11. Understand Your Medication

    Science.gov (United States)

    ... Disease Lookup > Asthma > Living with Asthma > Managing Asthma Understand Your Asthma Medication There are a variety of ... healthcare team. They can help make sure you understand the correct way to take the medicines, or ...

  12. Understanding Puberty (For Parents)

    Science.gov (United States)

    ... Safe Videos for Educators Search English Español Understanding Puberty KidsHealth / For Parents / Understanding Puberty What's in this ... your child through all the changes? Stages of Puberty Sure, most of us know the telltale signs ...

  13. 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....

  14. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... Understanding Cancer What Is Cancer? Cancer Statistics Cancer Disparities Understanding Cancer What Is Cancer Cancer Statistics Cancer Disparities Causes & Prevention Risk Factors Genetics Cancer Prevention Overview ...

  15. 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 ...

  16. 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.

  17. 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...

  18. 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.

  19. New method for determination of star formation history

    OpenAIRE

    Čeponis, Marius

    2017-01-01

    A New Method for Determination of Star Formation History Without stars there would not be any life and us. Almost all elements in our bodies are made in stars. Yet we still don‘t fully understand all the processes governing formation and evolution of stellar systems. Their star formation histories really help in trying to understand these processes. In this work a new Bayesian method for determination of star formation history is proposed. This method uses photometric data of resolved stars a...

  20. Understanding Obstacles to Peace

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

    1 Actors, Interests and Strategies in the Great Lakes Conflict Formation. 1 ...... can be assessed by exploring the extent to which elected and legally established ..... military officers have created corporate-military business ventures in order to ...

  1. 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.)

  2. 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 ...

  3. 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.

  4. Coevolutionary modeling in network formation

    KAUST Repository

    Al-Shyoukh, Ibrahim; Chasparis, Georgios; Shamma, Jeff S.

    2014-01-01

    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.

  5. From understanding to participation

    DEFF Research Database (Denmark)

    Raudaskoski, Pirkko Liisa

    2013-01-01

    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...... a residential home where mutual understanding is an everyday challenge, namely the Danish Acquired Brain Injury Centre North....

  6. Understanding Business Analytics

    Science.gov (United States)

    2015-01-05

    analytics have been used in organizations for a variety of reasons for quite some time; ranging from the simple (generating and understanding business analytics...process. understanding business analytics 3 How well these two components are orchestrated will determine the level of success an organization has in

  7. Conceptions of Musical Understanding

    Science.gov (United States)

    Hallam, Susan; Papageorgi, Ioulia

    2016-01-01

    Music can be understood in many ways. This has important implications for music education. The research reported here explored how groups of people conceptualise musical understanding and what they believe supports its acquisition. In this study 463 participants completed two statements: "Musical understanding is" and "You learn to…

  8. Approaches to understand culture

    DEFF Research Database (Denmark)

    Rasmussen, Lauge Baungaard; Rauner, Felix

    1996-01-01

    Different approaches to understand the concept ofculture are presented and evaluated. The author'sconcept of culture is defined. Different aspectsof the concept are discussed.......Different approaches to understand the concept ofculture are presented and evaluated. The author'sconcept of culture is defined. Different aspectsof the concept are discussed....

  9. 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.

  10. 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 ...

  11. Natural language understanding

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, S

    1982-04-01

    Language understanding is essential for intelligent information processing. Processing of language itself involves configuration element analysis, syntactic analysis (parsing), and semantic analysis. They are not carried out in isolation. These are described for the Japanese language and their usage in understanding-systems is examined. 30 references.

  12. Impact-Basin Formation on Mercury: Current Observations and Outstanding Questions

    Science.gov (United States)

    Baker, D. M. H.; Head, J. W.; Fassett, C. I.

    2018-05-01

    Mercury provides an important laboratory for understanding impact-basin formation on planetary bodies. MESSENGER observations improved our understanding, but much is still unknown about the formation and evolution of basin features.

  13. Understanding community traits - understanding public concerns

    International Nuclear Information System (INIS)

    Wlodarczyk, T.

    2003-01-01

    No two communities are alike. Therefore, one should not expect that public concerns and socio-economic effects of a proposed undertaking would be the same everywhere. Public concerns and the potential for social and economic effects of nuclear waste management facilities in one community will be different from those in another because communities differ in their fundamental sociological and economic traits. Research and experience with various types of nuclear and hazardous waste management facilities, generating stations and other energy developments across Canada and the United States indicate that an analysis of only a few key community traits can yield a more thorough understanding of the ways in which a community might perceive and respond to a project, the kinds of concerns that might dominate the public agenda, and the types of socio-economic effects that will be of primary concern. (author)

  14. Why adult formation

    Directory of Open Access Journals (Sweden)

    Andrej Justinek

    1997-01-01

    Full Text Available The article argues that the primary aim of adult formation is comprehensive personality development which is supposed to ensure quality existence in modern world. The article also suggests that formarion is a permanent process. Justinek puts special emphasis on adult formation methodology and defines fundamental formation styles which encourage independent action in individuals. Justinek differentiates between formation and education. methods and concludes that formation methods are related to the emotional sphere of personality, and education methods mostly to the rational. Justinek believes that formation of adults is based primarily on appropriate formation methodology.

  15. 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...

  16. 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, ...

  17. 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 ...

  18. Understanding Blood Pressure Readings

    Science.gov (United States)

    ... Venous Thromboembolism Aortic Aneurysm More Understanding Blood Pressure Readings Updated:Jun 1,2018 What do your blood ... and Live Our Interactive Cardiovascular Library has detailed animations and illustrations to help you learn about conditions, ...

  19. 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., a national expert on doctor-patient communications, talks with one of his patients about what ...

  20. 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)

  1. Understanding Vector Fields.

    Science.gov (United States)

    Curjel, C. R.

    1990-01-01

    Presented are activities that help students understand the idea of a vector field. Included are definitions, flow lines, tangential and normal components along curves, flux and work, field conservation, and differential equations. (KR)

  2. Brain Basics: Understanding Sleep

    Science.gov (United States)

    ... You are here Home » Disorders » Patient & Caregiver Education Brain Basics: Understanding Sleep Anatomy of Sleep Sleep Stages ... t form or maintain the pathways in your brain that let you learn and create new memories, ...

  3. 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 ...

  4. 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 ...

  5. Understanding Your Cancer Prognosis

    Science.gov (United States)

    Understanding Your Cancer Prognosis is the main video in the NCI Prognosis Video Series, which offers the perspectives of three cancer patients and their doctor, an oncologist who is also a national expert in doctor-patient communication.

  6. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... D., a national expert on doctor-patient communications, talks with one of his patients about what she' ... understand what prognosis means and also hard to talk about, even for doctors. Many Factors Can Affect ...

  7. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... disease will go for you is called prognosis. It can be hard to understand what prognosis means ... prognosis include: The type of cancer and where it is in your body The stage of the ...

  8. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... to talk about, even for doctors. Many Factors Can Affect Your Prognosis Some of the factors that ... Understanding your cancer and knowing what to expect can help you and your loved ones make decisions. ...

  9. Understanding your cancer prognosis

    Science.gov (United States)

    ... about: Treatment Palliative care Personal matters such as finances Knowing what to expect may make it easier ... treatment. www.cancer.net/navigating-cancer-care/cancer-basics/understanding-statistics-used-guide-prognosis-and-evaluate-treatment . ...

  10. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... Understanding Cancer Prognosis Oncologist Anthony L. Back, M.D., a national expert on doctor-patient communications, talks with one of his patients about what she'd like to know of her prognosis. Credit: National ...

  11. Tinnitus: Understanding the Facts

    Science.gov (United States)

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

  12. Understanding Yugoslavia's Killing Fields

    National Research Council Canada - National Science Library

    Swigert, James W

    1994-01-01

    Since Yugoslavia disintegrated in violence 3 years ago, observers have struggled to understand why the Yugoslav conflict has been so brutal and has involved such extensive violence against civilian populations...

  13. 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 ...

  14. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... you have cancer, you and your loved ones face many unknowns. Understanding your cancer and knowing what ... make decisions. Some of the decisions you may face include: Which treatment is best for you If ...

  15. Understanding Teen Dating Violence

    Science.gov (United States)

    Understanding Teen Dating Violence Fact Sheet 2014 Dating violence is a type of intimate partner violence. It occurs between two people in a close relationship. The nature of dating violence can be physical, emotional, or sexual. • Physical— This ...

  16. Understanding health insurance plans

    Science.gov (United States)

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

  17. Understanding Medical Words

    Science.gov (United States)

    ... Bar Home Current Issue Past Issues Understanding Medical Words Past Issues / Summer 2009 Table of Contents For ... Medicine that teaches you about many of the words related to your health care Do you have ...

  18. 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.

  19. Toward understanding insulin fibrillation.

    Science.gov (United States)

    Brange, J; Andersen, L; Laursen, E D; Meyn, G; Rasmussen, E

    1997-05-01

    Formation of insulin fibrils is a physical process by which partially unfolded insulin molecules interact with each other to form linear aggregates. Shielding of hydrophobic domains is the main driving force for this process, but formation of intermolecular beta-sheet may further stabilize the fibrillar structure. Conformational displacement of the B-chain C-terminal with exposure of nonpolar, aliphatic core residues, including A2, A3, B11, and B15, plays a crucial role in the fibrillation process. Recent crystal analyses and molecular modeling studies have suggested that when insulin fibrillates this exposed domain interacts with a hydrophobic surface domain formed by the aliphatic residues A13, B6, B14, B17, and B18, normally buried when three insulin dimers form a hexamer. In rabbit immunization experiments, insulin fibrils did not elicit an increased immune response with respect to formation of IgG insulin antibodies when compared with native insulin. In contrast, the IgE response increased with increasing content of insulin in fibrillar form. Strategies and practical approaches to prevent insulin from forming fibrils are reviewed. Stabilization of the insulin hexameric structure and blockage of hydrophobic interfaces by addition of surfactants are the most effective means of counteracting insulin fibrillation.

  20. 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...

  1. 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...

  2. 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...

  3. Understanding jet noise.

    Science.gov (United States)

    Karabasov, S A

    2010-08-13

    Jets are one of the most fascinating topics in fluid mechanics. For aeronautics, turbulent jet-noise modelling is particularly challenging, not only because of the poor understanding of high Reynolds number turbulence, but also because of the extremely low acoustic efficiency of high-speed jets. Turbulent jet-noise models starting from the classical Lighthill acoustic analogy to state-of-the art models were considered. No attempt was made to present any complete overview of jet-noise theories. Instead, the aim was to emphasize the importance of sound generation and mean-flow propagation effects, as well as their interference, for the understanding and prediction of jet noise.

  4. 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)

  5. Promoting proximal formative assessment with relational discourse

    Science.gov (United States)

    Scherr, Rachel E.; Close, Hunter G.; McKagan, Sarah B.

    2012-02-01

    The practice of proximal formative assessment - the continual, responsive attention to students' developing understanding as it is expressed in real time - depends on students' sharing their ideas with instructors and on teachers' attending to them. Rogerian psychology presents an account of the conditions under which proximal formative assessment may be promoted or inhibited: (1) Normal classroom conditions, characterized by evaluation and attention to learning targets, may present threats to students' sense of their own competence and value, causing them to conceal their ideas and reducing the potential for proximal formative assessment. (2) In contrast, discourse patterns characterized by positive anticipation and attention to learner ideas increase the potential for proximal formative assessment and promote self-directed learning. We present an analysis methodology based on these principles and demonstrate its utility for understanding episodes of university physics instruction.

  6. FORMATION CONSTANTS AND THERMODYNAMIC ...

    African Journals Online (AJOL)

    KEY WORDS: Metal complexes, Schiff base ligand, Formation constant, DFT calculation ... best values for the formation constants of the proposed equilibrium model by .... to its positive charge distribution and the ligand deformation geometry.

  7. Understanding Contemporary Terrorism.

    Science.gov (United States)

    Mitchell, Thomas H.

    1989-01-01

    Discusses the issue of terrorism as it exists today and examines progress that has been made toward understanding its dimensions. Suggests how this subject can be explored in the classroom. Dispels misconceptions about terrorism by defining the term, and examines some causes of terrorism and strategies employed by terrorists. (KO)

  8. Understanding the structure

    Science.gov (United States)

    David J. Nowak

    1994-01-01

    Urban forests are complex ecosystems created by the interaction of anthropogenic and natural processes. One key to better management of these systems is to understand urban forest structure and its relationship to forest functions. Through sampling and inventories, urban foresters often obtain structural information (e.g., numbers, location, size, and condition) on...

  9. 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...

  10. Understanding modern transparency

    NARCIS (Netherlands)

    Meijer, A.J.|info:eu-repo/dai/nl/172436729

    2009-01-01

    Proponents and opponents fiercely debate whether computer-mediated transparency has a positive effect on trust in the public sector. This article enhances our understanding of transparency by presenting three perspectives: a premodern, modern and post-modern perspective, and analyzing the basic

  11. Understanding Your Water Bill

    Science.gov (United States)

    An easy to way to understand individual water use is to look at your water bill—not just the amount due, but how much water you used. Pull out your water bill and follow our steps to learn more about it.

  12. 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…

  13. Understanding Acid Rain

    Science.gov (United States)

    Damonte, Kathleen

    2004-01-01

    The term acid rain describes rain, snow, or fog that is more acidic than normal precipitation. To understand what acid rain is, it is first necessary to know what an acid is. Acids can be defined as substances that produce hydrogen ions (H+), when dissolved in water. Scientists indicate how acidic a substance is by a set of numbers called the pH…

  14. 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

  15. 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…

  16. 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…

  17. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... Español 1-800-4-CANCER Live Chat Publications Dictionary Menu Contact Dictionary Search About Cancer Causes and Prevention Risk Factors ... Managing Cancer Care Finding Health Care Services Costs & Medical Information Advance Directives Using Trusted Resources Understanding Cancer ...

  18. 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.

  19. Understanding Dyscalculia for Teaching

    Science.gov (United States)

    Vaidya, Sheila Rao

    2004-01-01

    Dyscalculia, a poor understanding of the number concept and the number system, is a learning problem affecting many individuals. However, less is known about this disability than about the reading disability, dyslexia, because society accepts learning problems in mathematics as quite normal. This article provides a summary of the research on…

  20. Understanding your capital options.

    Science.gov (United States)

    Payne, Christopher T

    2012-05-01

    When planning capital expenditures, hospitals and health systems should understand the following financing considerations: Traditional fixed-rate tax-exempt bonds; Variable-rate financing alternatives; Basel III Accord requirements; Direct tax-exempt bank loans; Total return swaps Taxable financings; Interest-rate swaps and collateral requirements

  1. Early Understanding of Equality

    Science.gov (United States)

    Leavy, Aisling; Hourigan, Mairéad; McMahon, Áine

    2013-01-01

    Quite a bit of the arithmetic in elementary school contains elements of algebraic reasoning. After researching and testing a number of instructional strategies with Irish third graders, these authors found effective methods for cultivating a relational concept of equality in third-grade students. Understanding equality is fundamental to algebraic…

  2. 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 ...

  3. Understanding Cancer Prognosis

    Medline Plus

    Full Text Available ... a link to this page included, e.g., “Understanding Cancer Prognosis was originally published by the National Cancer Institute.” Please note that blog posts that are written by individuals from outside the government may be owned by the writer, and graphics ...

  4. 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…

  5. Understanding and using quality information for quality improvement: the effect of information presentation.

    NARCIS (Netherlands)

    Zwijnenberg, N.C.; Hendriks, M.; Delnoij, D.M.J.; Veer, A.J.E. de; Spreeuwenberg, P.; Wagner, C.

    2016-01-01

    Objective: To examine how information presentation affects the understanding and use of information for quality improvement. Design: An experimental design, testing 22 formats, and showing information on patient safety culture. Formats differed in visualization, outcomes and benchmark

  6. Understanding and using quality information for quality improvement : The effect of information presentation

    NARCIS (Netherlands)

    Zwijnenberg, N.C.; Hendriks, M.; Delnoij, D.; De Veer, A.J.; Spreeuwenberg, P.; Wagner, C.

    2016-01-01

    Objective To examine how information presentation affects the understanding and use of information for quality improvement. Design An experimental design, testing 22 formats, and showing information on patient safety culture. Formats differed in visualization, outcomes and benchmark information.

  7. Theory of aurora formation

    International Nuclear Information System (INIS)

    Hasegawa, Akira.

    1975-04-01

    A new theory of aurora formation is presented based on Alfven wave-electron interaction. The theory explains consistently 1) the electron acceleration process, 2) the formation of auroral layers and 3) the long wave formation in the longitudinal direction. (auth.)

  8. 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.

  9. 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"....

  10. 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...

  11. Towards Better Understanding QBism.

    Science.gov (United States)

    Khrennikov, Andrei

    2018-01-01

    Recently I posted a paper entitled "External observer reflections on QBism". As any external observer, I was not able to reflect all features of QBism properly. The comments I received from one of QBism's creators, C. A. Fuchs, were very valuable to me in better understanding the views of QBists. Some of QBism's features are very delicate and extracting them from articles of QBists is not a simple task. Therefore, I hope that the second portion of my reflections on QBism (or, strictly speaking, my reflections on Fuchs reflections on my earlier reflections) might be interesting and useful for other experts in quantum foundations and quantum information theory (especially, taking into account my previous aggressively anti-QBism position). In the present paper I correct some of my earlier posted critical comments on QBism. At the same time, other critical comments gained new validation through my recent deeper understanding of QBists views on a number of problems.

  12. THE BLACK HOLE FORMATION PROBABILITY

    Energy Technology Data Exchange (ETDEWEB)

    Clausen, Drew; Piro, Anthony L.; Ott, Christian D., E-mail: dclausen@tapir.caltech.edu [TAPIR, Walter Burke Institute for Theoretical Physics, California Institute of Technology, Mailcode 350-17, Pasadena, CA 91125 (United States)

    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 {sub BH}(M {sub ZAMS}). Although we find that it is difficult to derive a unique P {sub BH}(M {sub ZAMS}) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P {sub BH}(M {sub 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 {sub BH}(M {sub 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.

  13. 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

  14. 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.

  15. Intention Understanding in Autism

    Science.gov (United States)

    Boria, Sonia; Fabbri-Destro, Maddalena; Cattaneo, Luigi; Sparaci, Laura; Sinigaglia, Corrado; Santelli, Erica; Cossu, Giuseppe; Rizzolatti, Giacomo

    2009-01-01

    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. PMID:19440332

  16. Understanding traditional African healing

    OpenAIRE

    MOKGOBI, M.G.

    2014-01-01

    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 tradition...

  17. 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)

  18. 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)

  19. 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...

  20. The Understanding of libertarianism

    Directory of Open Access Journals (Sweden)

    Hubert Staśkiewicz

    2015-03-01

    Full Text Available This scientific article treats of libertarianism. This school of political thought is based on methodological individualism, methodological subjectivism, anti-empiricism, apriorism. Libertarian philosophers demand almost absolute freedom in every area of life and that is why they are at the opposite pole to all totalitarian ideologies. The greatest influence on the understanding of libertarianism had Carl Menger, Murray Rothbard and David Nolan.

  1. 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.

  2. Advances in understanding hypopituitarism

    OpenAIRE

    Stieg, Mareike R.; Renner, Ulrich; Stalla, G?nter K.; Kopczak, Anna

    2017-01-01

    The understanding of hypopituitarism has increased over the last three years. This review provides an overview of the most important recent findings. Most of the recent research in hypopituitarism has focused on genetics. New diagnostic techniques like next-generation sequencing have led to the description of different genetic mutations causative for congenital dysfunction of the pituitary gland while new molecular mechanisms underlying pituitary ontogenesis have also been described. Furtherm...

  3. Exploring the value of usability feedback formats

    DEFF Research Database (Denmark)

    Nørgaard, Mie; Hornbæk, Kasper Anders Søren

    2009-01-01

    The format used to present feedback from usability evaluations to developers affects whether problems are understood, accepted, and fixed. Yet, little research has investigated which formats are the most effective. We describe an explorative study where three developers assess 40 usability findings...... 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...

  4. 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.

  5. Understanding Unemployment Hysteresis

    DEFF Research Database (Denmark)

    Møller, Niels Framroze

    What explains the persistence of unemployment? The literature on hysteresis, which is based on unit root testing in autoregressive models, consists of a vast number of univariate studies, i.e. that analyze unemployment series in isolation, but few multivariate analyses that focus on the sources...... of hysteresis. As a result, this question remains largely unanswered. This paper presents a multivariate econometric framework for analyzing hysteresis, which allows one to test different hypotheses about non-stationarity of unemployment against one another. For example, whether this is due to a persistently...... to UK quarterly data on prices, wages, output, unemployment and crude oil prices, suggests that, for the period 1988 up to the onset of the …financial crisis, the non-stationarity of UK unemployment cannot be explained as a result of slow adjustment, including sluggish wage formation as emphasized...

  6. Recent advances in understanding schizophrenia.

    Science.gov (United States)

    Haller, Chiara S; Padmanabhan, Jaya L; Lizano, Paulo; Torous, John; Keshavan, Matcheri

    2014-01-01

    Schizophrenia is a highly disabling disorder whose causes remain to be better understood, and treatments have to be improved. However, several recent advances have been made in diagnosis, etiopathology, and treatment. Whereas reliability of diagnosis has improved with operational criteria, including Diagnostic and Statistical Manual of Mental Disorders, (DSM) Fifth Edition, validity of the disease boundaries remains unclear because of substantive overlaps with other psychotic disorders. Recent emphasis on dimensional approaches and translational bio-behavioral research domain criteria may eventually help move toward a neuroscience-based definition of schizophrenia. The etiology of schizophrenia is now thought to be multifactorial, with multiple small-effect and fewer large-effect susceptibility genes interacting with several environmental factors. These factors may lead to developmentally mediated alterations in neuroplasticity, manifesting in a cascade of neurotransmitter and circuit dysfunctions and impaired connectivity with an onset around early adolescence. Such etiopathological understanding has motivated a renewed search for novel pharmacological as well as psychotherapeutic targets. Addressing the core features of the illness, such as cognitive deficits and negative symptoms, and developing hypothesis-driven early interventions and preventive strategies are high-priority goals for the field. Schizophrenia is a severe, chronic mental disorder and is among the most disabling disorders in all of medicine. It is estimated by the National Institute of Mental Health (NIMH) that 2.4 million people over the age of 18 in the US suffer from schizophrenia. This illness typically begins in adolescence and derails the formative goals of school, family, and work, leading to considerable suffering and disability and reduced life expectancy by about 20 years. Treatment outcomes are variable, and some people are successfully treated and reintegrated (i.e. go back to work

  7. Understanding Teen UX

    DEFF Research Database (Denmark)

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

    2014-01-01

    UX is a widely explored topic within HCI and has a large practitioners' community. However, the users considered in research and practice, are most often adults -- since adults represent the largest technology market share. However teenagers represent a growing market of unique users, and more...... 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...

  8. 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...

  9. Understanding the bubbles

    DEFF Research Database (Denmark)

    Turcan, Romeo V.

    that are identified to exist between the Internet and housing market bubbles: uncertainty and sentiments. The iteration between uncertainty and sentiments leads to the emergence of the third commonality: residue. The residue is the difference between the actors’ overall sentiment about exaggerated future prospects...... 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....

  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. 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

  12. Understanding Infusion Pumps.

    Science.gov (United States)

    Mandel, Jeff E

    2018-04-01

    Infusion systems are complicated electromechanical systems that are used to deliver anesthetic drugs with moderate precision. Four types of systems are described-gravity feed, in-line piston, peristaltic, and syringe. These systems are subject to a number of failure modes-occlusion, disconnection, siphoning, infiltration, and air bubbles. The relative advantages of the various systems and some of the monitoring capabilities are discussed. A brief example of the use of an infusion system during anesthetic induction is presented. With understanding of the functioning of these systems, users may develop greater comfort.

  13. Understanding disruptions in tokamaksa)

    Science.gov (United States)

    Zakharov, Leonid E.; Galkin, Sergei A.; Gerasimov, Sergei N.; contributors, JET-EFDA

    2012-05-01

    This paper describes progress achieved since 2007 in understanding disruptions in tokamaks, when the effect of plasma current sharing with the wall was introduced into theory. As a result, the toroidal asymmetry of the plasma current measurements during vertical disruption event (VDE) on the Joint European Torus was explained. A new kind of plasma equilibria and mode coupling was introduced into theory, which can explain the duration of the external kink 1/1 mode during VDE. The paper presents first results of numerical simulations using a free boundary plasma model, relevant to disruptions.

  14. Understanding Our Only Universe

    Directory of Open Access Journals (Sweden)

    Valerio Marra

    2017-09-01

    Full Text Available In an imaginary dialogue between a professor and a layman about the future of cosmology, the said professor relates the paradoxical story of scientist Zee Prime, a bold thinker of a future civilization, stuck in a lonely galaxy, forever unaware of the larger universe. Zee Prime comes to acknowledge his position and shows how important it is to question standard models and status quo, as only the most imaginative ideas give us the chance to understand what he calls “our only universe” — the special place and time in which we live.

  15. 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.

  16. Students' understandings of electrochemistry

    Science.gov (United States)

    O'Grady-Morris, Kathryn

    Electrochemistry is considered by students to be a difficult topic in chemistry. This research was a mixed methods study guided by the research question: At the end of a unit of study, what are students' understandings of electrochemistry? The framework of analysis used for the qualitative and quantitative data collected in this study was comprised of three categories: types of knowledge used in problem solving, levels of representation of knowledge in chemistry (macroscopic, symbolic, and particulate), and alternative conceptions. Although individually each of the three categories has been reported in previous studies, the contribution of this study is the inter-relationships among them. Semi-structured, task-based interviews were conducted while students were setting up and operating electrochemical cells in the laboratory, and a two-tiered, multiple-choice diagnostic instrument was designed to identify alternative conceptions that students held at the end of the unit. For familiar problems, those involving routine voltaic cells, students used a working-forwards problem-solving strategy, two or three levels of representation of knowledge during explanations, scored higher on both procedural and conceptual knowledge questions in the diagnostic instrument, and held fewer alternative conceptions related to the operation of these cells. For less familiar problems, those involving non-routine voltaic cells and electrolytic cells, students approached problem-solving with procedural knowledge, used only one level of representation of knowledge when explaining the operation of these cells, scored higher on procedural knowledge than conceptual knowledge questions in the diagnostic instrument, and held a greater number of alternative conceptions. Decision routines that involved memorized formulas and procedures were used to solve both quantitative and qualitative problems and the main source of alternative conceptions in this study was the overgeneralization of theory

  17. Understanding postoperative fatigue.

    Science.gov (United States)

    Rose, E A; King, T C

    1978-07-01

    Performance characteristics of the central nervous, cardiovascular, respiratory and muscular systems in man postoperatively have received little investigative attention, despite the well known syndrome of postoperative fatigue. The impairmen in perception and psychomotor skills that has been shown to result from caloric restriction, bedrest, sedation and sleep deprivation suggests that a similar deficit may occur after surgical procedures. After a simple elective surgical procedure, maximal oxygen uptake decreases and the adaptability of heart rate to submaximal workloads is impaired. Similar deleterious effects on cardiorespiratory performance have been documented with starvation and bedrest; an understanding of cardiorespiratory performance postoperatively awaits further investigation. Maximal muscular force of contraction is also impaired by caloric restriction and bedrest, suggesting that similar effects may be seen in the postoperative state, although this has not been studied. A better understanding of the syndrome of postoperative fatigue could be achieved by a descriptive analysis of physiologic performance postoperatively. Such descriptive data could form the basis for objective evaluation of therapeutic measures intended to improve performance, such as nutritional supplementation and pharmacologic intervention. The observation that exercise with the patient in the supine position may decrease the impairment in maximal aerobic power otherwise expected in immobilized patients suggests that controlled exercise therapy may be of value in reducing physiologic impairment postoperatively.

  18. Understanding nurse practitioner autonomy.

    Science.gov (United States)

    Weiland, Sandra A

    2015-02-01

    This Gadamerian hermeneutic study was undertaken to understand the meaning of autonomy as interpreted by nurse practitioners (NPs) through their lived experiences of everyday practice in primary health care. A purposive sample of nine NPs practicing in primary health care was used. Network sampling achieved a broad swath of primary care NPs and practice settings. Data were collected by face-to-face interviews. Because NP autonomy is concerned with gender and marginalization, Gilligan's feminist perspective was utilized during interpretive analysis. Having Genuine NP Practice was the major theme, reflecting the participants' overall meaning of their autonomy. Practicing alone with the patient provided the context within which participants shaped the meaning of Having Genuine NP Practice. Having Genuine NP Practice had four subthemes: relationships, self-reliance, self-empowerment, and defending the NP role. The understanding of Having Genuine NP Practice will enable NPs to articulate their autonomy clearly and better influence healthcare reform. Implications for advanced practice nursing education include integrating findings into classroom discussion to prompt self-reflection of what autonomy means and socialization to the NP role. ©2014 American Association of Nurse Practitioners.

  19. 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.

  20. 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

  1. 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

  2. Planet formation in Binaries

    OpenAIRE

    Thebault, Ph.; Haghighipour, N.

    2014-01-01

    Spurred by the discovery of numerous exoplanets in multiple systems, binaries have become in recent years one of the main topics in planet formation research. Numerous studies have investigated to what extent the presence of a stellar companion can affect the planet formation process. Such studies have implications that can reach beyond the sole context of binaries, as they allow to test certain aspects of the planet formation scenario by submitting them to extreme environments. We review her...

  3. 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

  4. 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)

  5. 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....

  6. 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...

  7. 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...

  8. 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.

  9. 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.

  10. Understanding Socio Technical Modularity

    DEFF Research Database (Denmark)

    Thuesen, Christian Langhoff; Kudsk, Anders; Hvam, Lars

    2011-01-01

    Modularity has gained an increasing popularity as a central concept for exploring product structure, process structure, organization structure and supply chain structure. With the offset in system theory the predominant understanding of modularity however faces difficulties in explaining the social...... dimension of modularity like irrational behaviors, cultural differences, learning processes, social organization and institutional influences on modularity. The paper addresses this gab offering a reinterpretation of the modularity concept from a socio-technical perspective in general and Actor Network...... Theory in particular. By formulating modularity from an ANT perspective covering social, material and process aspects, the modularity of a socio-technical system can be understood as an entanglement of product, process, organizational and institutional modularity. The theoretical framework is illustrated...

  11. Understanding ADHD through entification

    DEFF Research Database (Denmark)

    Nielsen, Mikka

    How do we perceive ourselves and what explanations are we drawing upon in order to understand ourselves as morally acting individuals? In this presentation, I focus on how we live with, accept, and work on parts of ourselves that we find less desirable or even pathological. Based on interviews wi...... of acknowledging that some actions are beyond control; and 2) a way of concretising problematic actions and parts of oneself in order to work on and subdue these traits and reactions....... as a part of the self, a kind of quirk, and on the other hand as separated from the self, a foreign agent. By making a parallel to phenomena as spirit possession, I discuss how the entification process can be understood as 1) a distancing to what is perceived as amoral actions and a liberating process...

  12. Understanding renewable energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Quaschning, Volker

    2005-01-15

    Beginning with an overview of renewable energy sources including biomass, hydroelectricity, geothermal, tidal, wind and solar power, this book explores the fundamentals of different renewable energy systems. The main focus is on technologies with high development potential such as solar thermal systems, photovoltaics and wind power. This text not only describes technological aspects, but also deals consciously with problems of the energy industry. In this way, the topics are treated in a holistic manner, bringing together maths, engineering, climate studies and economics, and enabling readers to gain a broad understanding of renewable energy technologies and their potential. The book also contains a free CD-ROM resource, which includes a variety of specialist simulation software and detailed figures from the book. (Author)

  13. 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.)

  14. Understanding representations in design

    DEFF Research Database (Denmark)

    Bødker, Susanne

    1998-01-01

    Representing computer applications and their use is an important aspect of design. In various ways, designers need to externalize design proposals and present them to other designers, users, or managers. This article deals with understanding design representations and the work they do in design....... The article is based on a series of theoretical concepts coming out of studies of scientific and other work practices and on practical experiences from design of computer applications. The article presents alternatives to the ideas that design representations are mappings of present or future work situations...... and computer applications. It suggests that representations are primarily containers of ideas and that representation is situated at the same time as representations are crossing boundaries between various design and use activities. As such, representations should be carriers of their own contexts regarding...

  15. Expectation formation in dynamic market experiments

    NARCIS (Netherlands)

    Heemeijer, P.

    2009-01-01

    People often make mistakes when predicting economic variables such as prices. It is important to understand how these predictions are formed, since people's expectations have a large impact on the development and stability of economic systems. In this thesis the expectation formation of individuals

  16. 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…

  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. Formation of multiple networks

    DEFF Research Database (Denmark)

    Magnani, Matteo; Rossi, Luca

    2013-01-01

    we introduce the first network formation model for multiple networks. Network formation models are among the most popular tools in traditional network studies, because of both their practical and theoretical impact. However, existing models are not sufficient to describe the generation of multiple...

  19. 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...... preachers. This involves a learning strategy to ministry where theological skills, pastoral competences, and own personality are interwoven. Teaching here means facilitating a room of learning where teacher’s power and control is reduced, allowing the preacher to reflect upon own practice without being...... 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...

  20. 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

  1. Usage Record Format Recommendation

    CERN Document Server

    Nilsen, J.K.; Muller-Pfeerkorn, R

    2013-01-01

    For resources to be shared, sites must be able to exchange basic accounting and usage data in a common format. This document describes a common format which enables the exchange of basic accounting and usage data from different resources. This record format is intended to facilitate the sharing of usage information, particularly in the area of the accounting of jobs, computing, memory, storage and cloud usage but with a structure that allows an easy extension to other resources. This document describes the Usage Record components both in natural language form and annotated XML. This document does not address how these records should be used, nor does it attempt to dictate the format in which the accounting records are stored. Instead, it denes a common exchange format. Furthermore, nothing is said regarding the communication mechanisms employed to exchange the records, i.e. transport layer, framing, authentication, integrity, etc.

  2. 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.”

  3. 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

  4. Understanding Organizational Reality

    Directory of Open Access Journals (Sweden)

    Keith O. Owen

    2012-10-01

    Full Text Available To achieve their purposes, organizations must constantly learn, adapt, and grow, a process typically referred to as change. Research shows that only a relatively few change efforts achieve great success—most just get by while the majority fail to reach predefined performance goals and objectives. That the success of planned change is relatively rare led to the following questions: (a What facilitates or inhibits the change process? (b How do these facilitators and inhibitors evolve within an organization? and (c What are the implications of understanding this evolutionary process relative to achieving a more sustainable level of performance? This article addresses these questions and presents a holistic model for creating an open, fully transparent environment in which the many differences of potential relevance to a change are put in the open for analysis. The approach, the Full Dimensional Systems Model, assumes there are multiple, interrelated domains of influence that affect change and that these must each be appreciated and addressed simultaneously to achieve sustainable performance improvement.

  5. 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.

  6. Understanding portable generators

    Energy Technology Data Exchange (ETDEWEB)

    Hills, A.; Hawkins, B. [Guelph Univ., ON (Canada); Clarke, S. [Ontario Ministry of Agriculture, Food and Rural Affairs, Toronto, ON (Canada)

    2000-06-01

    This factsheet is intended to help consumers select a small portable generator for emergency electrical needs. Interest in standby generators has been heightened ever since the prolonged power outage in Eastern Ontario and Southwestern Quebec during the 1998 ice storm and the concern over Y2K related outages. Farmers, in particular, have been reassessing their need for emergency electrical power supply. This document presents some of the factors that should be considered when purchasing and operating a portable generator in the 3 to 12 kW size. It provides a detailed review of power quality and describes the use of tractor-driven power-take-off generators of 15 kW and larger. Several manufacturers make portable generators in many sizes with a whole range of features. This document includes a table depicting generator Feature/Benefit analysis to help consumers understand the differences between features and benefits. A second table provides a check list for generator feature/benefits. Specific details for the operations of various generators are available from manufacturers, distributors and electrical contractors. 2 tabs., 1 fig.

  7. 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."

  8. Advances in understanding hypopituitarism

    Science.gov (United States)

    Stieg, Mareike R.; Renner, Ulrich; Stalla, Günter K.; Kopczak, Anna

    2017-01-01

    The understanding of hypopituitarism has increased over the last three years. This review provides an overview of the most important recent findings. Most of the recent research in hypopituitarism has focused on genetics. New diagnostic techniques like next-generation sequencing have led to the description of different genetic mutations causative for congenital dysfunction of the pituitary gland while new molecular mechanisms underlying pituitary ontogenesis have also been described. Furthermore, hypopituitarism may occur because of an impairment of the distinctive vascularization of the pituitary gland, especially by disruption of the long vessel connection between the hypothalamus and the pituitary. Controversial findings have been published on post-traumatic hypopituitarism. Moreover, autoimmunity has been discussed in recent years as a possible reason for hypopituitarism. With the use of new drugs such as ipilimumab, hypopituitarism as a side effect of pharmaceuticals has come into focus. Besides new findings on the pathomechanism of hypopituitarism, there are new diagnostic tools in development, such as new growth hormone stimulants that are currently being tested in clinical trials. Moreover, cortisol measurement in scalp hair is a promising tool for monitoring cortisol levels over time. PMID:28299199

  9. 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.

  10. 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.

  11. Formation of interstellar anions

    Science.gov (United States)

    Senent, Maria Luisa

    2012-05-01

    Formation of interstellar anions: M.L. Senent. The recent detection of negative charged species in the ISM1 has instigated enthusiasm for anions in the astrophysical community2. Many of these species are new and entail characterization. How they are formed in astrophysical sources is a question of major relevance. The anion presence in ISM was first predicted theoretically on the basis of electron affinities and on the negative linear chain molecular stabilities. Although very early, they were considered in astrochemical models3-4, their discovery is so recent because their abundances seem to be relatively low. These have to be understood in terms of molecular stabilities, reaction probabilities and radiative and collisional excitations. Then, we present our theoretical work on even carbon chains type Cn and CnH (n=2,4,6) focused to the understanding of anion abundances. We use highly correlated ab initio methods. We performed spectroscopic studies of various isomers that can play important roles as intermediates5-8. In previous papers9-10, we compared C2H and C2H- collisional rates responsible for observed line intensities. Actually, we study hydrogen attachment (Cn +H → CnH and Cn- +H → CnH-) and associative detachment processes (Cn- +H → CnH +e-) for 2, 4 and 6 carbon atom chains11. [1] M.C.McCarthy, C.A.Gottlieb, H.Gupta, P.Thaddeus, Astrophys.J, 652, L141 (2006) [2] V.M.Bierbaum, J.Cernicharo, R.Bachiller, eds., 2011, pp 383-389. [3] A. Dalgarno, R.A. Mc Cray, Astrophys.J,, 181, 95 (1973) [4] E. Herbst E., Nature, 289, 656 (1981); [5] H.Massó, M.L.Senent, P.Rosmus, M.Hochlaf, J.Chem.Phys., 124, 234304 (2006) [6] M.L.Senent, M.Hochlaf, Astrophys. J. , 708, 1452(2010) [7] H.Massó, M.L.Senent, J.Phys.Chem.A, 113, 12404 (2009) [8] D. Hammoutene, M.Hochlaf, M.L.Senent, submitted. [9] A. Spielfiedel, N. Feautrier, F. Najar, D. ben Abdallah, F. Dayou, M.L. Senent, F. Lique, Mon.Not.R.Astron.Soc., 421, 1891 (2012) [10] F.Dumouchel, A, Spielfieldel , M

  12. 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

  13. 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.

  14. 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).

  15. Earth formation porosity log

    International Nuclear Information System (INIS)

    Smith, H.D.; Smith, M.P.; Schultz, W.E.

    1977-01-01

    A method for determining the porosity of earth formations in the vicinity of a cased well borehole is described, comprising the steps of: irradiating the earth formations in the vicinity of the cased well borehole with fast neutrons from a source of fast neutrons passed into the borehole; and generating a signal representative of the fast neutron population present in the well borehole at a location in the borehole, the signal is functionally related to the porosity of the earth formations in the vicinity of the borehole

  16. 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.

  17. Parental Understanding of Tuberous Sclerosis Complex.

    Science.gov (United States)

    Samia, Pauline; Donald, Kirsten A; Schlegel, Birgit; Wilmshurst, Jo M

    2015-09-01

    Tuberous sclerosis complex is a genetic disorder with multisystem involvement that poses significant challenges to the affected child and family. Caregiver knowledge in the South African population has not previously been reported. A prospective study of the parents of 21 children with tuberous sclerosis complex was undertaken. Median parental age was 38 (interquartile range 34.5-45) years. Parents were randomly allocated to receive written information about the condition, or to receive verbal counseling already established in clinic. A significant difference (P = .001) was observed in the change in the mean knowledge scores for the parent group that received written information (34.2 at baseline, 51.7 at the second visit. This impact was higher in parents with an education level of at least grade 8 (P = .003). Parental understanding of tuberous sclerosis complex can be improved by provision of written information and should be routinely available in a readily understandable format. © The Author(s) 2014.

  18. Current understanding of multi-species biofilms

    DEFF Research Database (Denmark)

    Yang, Liang; Liu, Yang; Wu, Hong

    2011-01-01

    every year worldwide to deal with damage to equipment, contaminations of products, energy losses, and infections in human beings resulted from microbial biofilms. Microorganisms compete, cooperate, and communicate with each other in multi-species biofilms. Understanding the mechanisms of multi......Direct observation of a wide range of natural microorganisms has revealed the fact that the majority of microbes persist as surface-attached communities surrounded by matrix materials, called biofilms. Biofilms can be formed by a single bacterial strain. However, most natural biofilms are actually......-species biofilm formation will facilitate the development of methods for combating bacterial biofilms in clinical, environmental, industrial, and agricultural areas. The most recent advances in the understanding of multi-species biofilms are summarized and discussed in the review....

  19. Reconsidering formative measurement.

    Science.gov (United States)

    Howell, Roy D; Breivik, Einar; Wilcox, James B

    2007-06-01

    The relationship between observable responses and the latent constructs they are purported to measure has received considerable attention recently, with particular focus on what has become known as formative measurement. This alternative to reflective measurement in the area of theory-testing research is examined in the context of the potential for interpretational confounding and a construct's ability to function as a point variable within a larger model. Although these issues have been addressed in the traditional reflective measurement context, the authors suggest that they are particularly relevant in evaluating formative measurement models. On the basis of this analysis, the authors conclude that formative measurement is not an equally attractive alternative to reflective measurement and that whenever possible, in developing new measures or choosing among alternative existing measures, researchers should opt for reflective measurement. In addition, the authors provide guidelines for researchers dealing with existing formative measures. Copyright 2007 APA, all rights reserved.

  20. Isothermal Martensite Formation

    DEFF Research Database (Denmark)

    Villa, Matteo

    Isothermal (i.e. time dependent) martensite formation in steel was first observed in the 40ies of the XXth century and is still treated as an anomaly in the description of martensite formation which is considered as a-thermal (i.e. independent of time). Recently, the clarification of the mechanism...... of lattice strains provided fundamental information on the state of stress in the material and clarified the role of the strain energy on martensite formation. Electron backscatter diffraction revealed that the microstructure of the material and the morphology of martensite were independent on the cooling...... leading to isothermal kinetics acquired new practical relevance because of the identification of isothermal martensite formation as the most likely process responsible for enhanced performances of sub-zero Celsius treated high carbon steel products. In the present work, different iron based alloys...

  1. 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

  2. Fracturing formations in wells

    Energy Technology Data Exchange (ETDEWEB)

    Daroza, R A

    1964-05-15

    This well stimulation method comprises introducing through the well bore a low-penetrating, dilatant fluid, and subjecting the fluid to sufficient pressure to produce fractures in the formation. The fluid is permitted to remain in contact with the formation so as to become diluted by the formation fluids, and thereby lose its properties of dilatancy. Also, a penetrating fluid, containing a propping agent suspended therein, in introduced into contact with the fractures at a pressure substantially reduced with respect to that pressure which would have been required, prior to the fracturing operation performed using the low-penetrating dilatant fluid. The propping agent is deposited within the fractures, and thereafter, fluid production is resumed from the fractured formation. (2 claims)

  3. Star formation: Cosmic feast

    Science.gov (United States)

    Scaringi, Simone

    2017-03-01

    Low-mass stars form through a process known as disk accretion, eating up material that orbits in a disk around them. It turns out that the same mechanism also describes the formation of more massive stars.

  4. 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.

  5. Plant Formate Dehydrogenase

    Energy Technology Data Exchange (ETDEWEB)

    John Markwell

    2005-01-10

    The research in this study identified formate dehydrogenase, an enzyme that plays a metabolic role on the periphery of one-carbon metabolism, has an unusual localization in Arabidopsis thaliana and that the enzyme has an unusual kinetic plasticity. These properties make it possible that this enzyme could be engineered to attempt to engineer plants with an improved photosynthetic efficiency. We have produced transgenic Arabidopsis and tobacco plants with increased expression of the formate dehydrogenase enzyme to initiate further studies.

  6. Topic 2.0: Tropical cyclone formation and extratropical transition

    OpenAIRE

    Harr, Patrick A.

    2010-01-01

    Approved for public release; distribution is unlimited In this section, progress since ITWC-VI on research, observations and forecasting of tropical cyclone formation and extratropical transition is summarized. While tropical cyclone formation and extratropical transition are stages at opposite ends of the tropical cyclone lifecycle, significant lack of understanding remains in relation to processes associated with each stage. Formation and extratropical transition involve interactions a...

  7. 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

  8. 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.

  9. 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....

  10. 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

  11. Formation mechanisms of metal colloids

    Science.gov (United States)

    Halaciuga, Ionel

    Highly dispersed uniform metallic particles are widely used in various areas of technology and medicine and are likely to be incorporated into many other applications in the future. It is commonly accepted that size, shape and composition of the particles represent critical factors in most applications. Thus, understanding the mechanisms of formation of metal particles and the ways to control the physical (e.g. shape, size) and chemical (e.g. composition) properties is of great importance. In the current research, the formation of uniform silver spheres is investigated experimentally. The parameters that influence the formation of silver particles when concentrated iso-ascorbic acid and silver-polyamine complex solutions are rapidly mixed were studied in the absence of dispersants. We found that by varying the nature of the amine, temperature, concentration of reactants, silver/amine molar ratio, and the nature of the silver salt, the size of the resulting silver particles can be varied in a wide range (0.08--1.5 microm). The silver particles were formed by aggregation of nanosize subunits as substantiated by both electron microscopy and X-ray diffraction techniques and by the vivid rapid color changes during the chemical precipitation process. From the practical standpoint, the goal of this research was to prepare well dispersed spherical silver particles having a relatively smooth surface and a diameter of about 1 microm to satisfy the demands of the current electronic materials market. A two stage particle growth model previously developed to explain the narrow size distribution occurring in synthesis of gold spheres was applied to the present experimental system, and the parameters that control the size distribution characteristics were identified. The kinetic parameter required to match the final particle size was found to be in agreement with the one used previously in modeling formation of gold spheres, suggesting that similar kinetics governs the

  12. 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

  13. 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.

  14. Blistering and bubble formation

    International Nuclear Information System (INIS)

    Roth, J.

    1976-01-01

    Blister formation in metals has been observed during bombardment with inert-gas ions in the energy range between 1 and 2000 keV at doses of about 10 17 to 10 19 cm -2 . The changes in surface topography and the erosion yields were mainly studied in the scanning electron microscope (SEM). Additionally the release of the implanted gas during blister formation was observed. Recently measurements on single crystals were performed determining simultaneously the implantation profile, the total amount of trapped ions, the depth distribution of the induced lattice damage and the thickness of the covers of the blisters. In several stages of the formation process of blisters the implanted layer was observed in the transmission electron microscope (TEM) showing the formation of gas bubbles. Using the results of all these measurements in this review an attempt is made to develop a model of blister formation combining the effects of hydrostatic pressure in the gas bubbles and lateral stress due to volume swelling. (author)

  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. Comparison of Brief Summary Formats Through a Health Literacy Lens.

    Science.gov (United States)

    Sharp, Michele L; Hall, Lori; Eleftherion, Anthony; Simpson, Katherine; Neuhauser, Linda

    2018-01-01

    Print pharmaceutical advertisements in the United States require inclusion of a brief summary of side effects, warnings, precautions, and contraindications from the labeling. The full package insert, which sponsors have traditionally used to fulfill the brief summary requirement, does not adhere to health literacy best practices, limiting its value to consumers. This study compared the understandability and usability of brief summaries in 3 formats designed to be more consumer friendly. Three brief summary formats were tested: (1) 2-column "Question and Answer"; (2) "Prescription Drug Facts Box," similar to current US over-the-counter drug facts labeling; and (3) "Health Literacy," based on clear communication principles. Researchers evaluated the formats using the Suitability Assessment of Materials (SAM) tool and conducted structured, scripted, one-on-one interviews (usability tests) with participants with estimated low to average education levels. This research was replicated across 2 therapeutic areas (type 2 diabetes and plaque psoriasis). SAM scores showed that the Health Literacy format outperformed the Question and Answer format and the Prescription Drug Facts Box format in both therapeutic areas, with both Health Literacy brief summaries rated on the SAM as "superior." Qualitative usability tests supported the SAM findings, with the Health Literacy format preferred consistently over the Question and Answer format, and more often than not over the Prescription Drug Facts Box format. Sponsors can employ a user-tested Health Literacy format to improve the understandability and usability of brief summaries with patients.

  18. 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.

  19. Meningococcal biofilm formation

    DEFF Research Database (Denmark)

    Lappann, M.; Haagensen, Janus Anders Juul; Claus, H.

    2006-01-01

    We show that in a standardized in vitro flow system unencapsulated variants of genetically diverse lineages of Neisseria meningitidis formed biofilms, that could be maintained for more than 96 h. Biofilm cells were resistant to penicillin, but not to rifampin or ciprofloxacin. For some strains......, microcolony formation within biofilms was observed. Microcolony formation in strain MC58 depended on a functional copy of the pilE gene encoding the pilus subunit pilin, and was associated with twitching of cells. Nevertheless, unpiliated pilE mutants formed biofilms showing that attachment and accumulation......X alleles was identified among genetically diverse meningococcal strains. PilX alleles differed in their propensity to support autoaggregation of cells in suspension, but not in their ability to support microcolony formation within biofilms in the continuous flow system....

  20. 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

  1. Observsational Planet Formation

    Science.gov (United States)

    Dong, Ruobing; Zhu, Zhaohuan; Fung, Jeffrey

    2017-06-01

    Planets form in gaseous protoplanetary disks surrounding newborn stars. As such, the most direct way to learn how they form from observations, is to directly watch them forming in disks. In the past, this was very difficult due to a lack of observational capabilities; as such, planet formation was largely a subject of pure theoretical astrophysics. Now, thanks to a fleet of new instruments with unprecedented resolving power that have come online recently, we have just started to unveil features in resolve images of protoplanetary disks, such as gaps and spiral arms, that are most likely associated with embedded (unseen) planets. By comparing observations with theoretical models of planet-disk interactions, the masses and orbits of these still forming planets may be constrained. Such planets may help us to directly test various planet formation models. This marks the onset of a new field — observational planet formation. I will introduce the current status of this field.

  2. Superclusters and galaxy formation

    International Nuclear Information System (INIS)

    Einasto, J.; Joeveer, M.; Saar, E.

    1979-01-01

    The spatial distribution of Galaxies and Galaxy congestions in the southern galactic hemisphere is studied. The rich galaxy congestions, containing many elliptic Galaxies and radiogalaxies, are linked with each other by chains of scanty congestions with moderate content of elliptic Galaxies and radiogalaxies. The flat formation, linking the density pikes and the intermediate chains, can reasonably be called supercongestion. In the central region of supercongestions there is a thin layer of Galaxies consisting of only spiral Galaxies. The neighbouring supercongestions touch each other, while the intersupercongestion space contains no Galaxy congestions and almost no Galaxies. It is shown that such a structure was, apparently, formed before the formation of Galaxies

  3. Formation of galaxies

    International Nuclear Information System (INIS)

    Szalay, A.S.

    1984-12-01

    The present theories of galaxy formation are reviewed. The relation between peculiar velocities and the correlation function of galaxies points to the possibility that galaxies do not form uniformly everywhere. Scale invariant properties of the cluster-cluster correlations are discussed. Comparing the correlation functions in a dimensionless way, galaxies appear to be stronger clustered, in contrast with the comparison of the dimensional amplitudes of the correlation functions. Theoretical implications of several observations as Lyman-α clouds, correlations of faint galaxies are discussed. None of the present theories of galaxy formation can account for all facts in a natural way. 29 references

  4. 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

  5. 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

    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......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...

  6. Formative Assessment and the Classroom Teacher: Recommendations for School Psychologists

    Science.gov (United States)

    Williams, Stacy A. S.; Stenglein, Katherine

    2016-01-01

    In order for school psychologists to effectively work with teachers, it is important to understand not only the context in which they work, but to understand how educators consider and subsequently use data. Therefore, the purpose of this article is to examine how formative assessments are conceptualized in teacher training and pedagogical…

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

    International Nuclear Information System (INIS)

    Slattery, Stuart R.; Gurecky, William L.

    2016-01-01

    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.

  8. 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.

  9. Radiolytic formation of iron oxyhydroxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, T.; Wren, J.C., E-mail: tsuther4@uwo.ca [The Univ. of Western Ontario, London, ON (Canada)

    2014-07-01

    The formation of iron oxyhydroxide nanoparticles under gamma irradiation of ferrous ion solutions is a process in the infancy of its understanding. Herein we present work to probe the mechanism by which these nanoparticles are formed. These results can be used to better understand the activity transport processes occurring within a reactor environment which may pose both environmental and safety concerns. Initial ferrous concentrations and solution pH were modified and found to have little effect on final particle size and composition. The nanoparticles were formed in the presence of scavengers and it was found that hydroxyl radicals promote the particle formation while solvated electrons diminish it. Post-synthesis heating was found to shift the initially-formed lepidocrocite particles towards a mixture of goethite and maghemite. (author)

  10. Insights from simulations of star formation

    International Nuclear Information System (INIS)

    Larson, Richard B

    2007-01-01

    Although the basic physics of star formation is classical, numerical simulations have yielded essential insights into how stars form. They show that star formation is a highly nonuniform runaway process characterized by the emergence of nearly singular peaks in density, followed by the accretional growth of embryo stars that form at these density peaks. Circumstellar discs often form from the gas being accreted by the forming stars, and accretion from these discs may be episodic, driven by gravitational instabilities or by protostellar interactions. Star-forming clouds typically develop filamentary structures, which may, along with the thermal physics, play an important role in the origin of stellar masses because of the sensitivity of filament fragmentation to temperature variations. Simulations of the formation of star clusters show that the most massive stars form by continuing accretion in the dense cluster cores, and this again is a runaway process that couples star formation and cluster formation. Star-forming clouds also tend to develop hierarchical structures, and smaller groups of forming objects tend to merge into progressively larger ones, a generic feature of self-gravitating systems that is common to star formation and galaxy formation. Because of the large range of scales and the complex dynamics involved, analytic models cannot adequately describe many aspects of star formation, and detailed numerical simulations are needed to advance our understanding of the subject. 'The purpose of computing is insight, not numbers.' Richard W Hamming, in Numerical Methods for Scientists and Engineers (1962) 'There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.' William Shakespeare, in Hamlet, Prince of Denmark (1604) (key issues review)

  11. Insights from simulations of star formation

    Energy Technology Data Exchange (ETDEWEB)

    Larson, Richard B [Department of Astronomy, Yale University, Box 208101, New Haven, CT 06520-8101 (United States)

    2007-03-15

    Although the basic physics of star formation is classical, numerical simulations have yielded essential insights into how stars form. They show that star formation is a highly nonuniform runaway process characterized by the emergence of nearly singular peaks in density, followed by the accretional growth of embryo stars that form at these density peaks. Circumstellar discs often form from the gas being accreted by the forming stars, and accretion from these discs may be episodic, driven by gravitational instabilities or by protostellar interactions. Star-forming clouds typically develop filamentary structures, which may, along with the thermal physics, play an important role in the origin of stellar masses because of the sensitivity of filament fragmentation to temperature variations. Simulations of the formation of star clusters show that the most massive stars form by continuing accretion in the dense cluster cores, and this again is a runaway process that couples star formation and cluster formation. Star-forming clouds also tend to develop hierarchical structures, and smaller groups of forming objects tend to merge into progressively larger ones, a generic feature of self-gravitating systems that is common to star formation and galaxy formation. Because of the large range of scales and the complex dynamics involved, analytic models cannot adequately describe many aspects of star formation, and detailed numerical simulations are needed to advance our understanding of the subject. 'The purpose of computing is insight, not numbers.' Richard W Hamming, in Numerical Methods for Scientists and Engineers (1962) 'There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.' William Shakespeare, in Hamlet, Prince of Denmark (1604) (key issues review)

  12. Stratigraphy and dissolution of the Rustler Formation

    International Nuclear Information System (INIS)

    Bachman, G.O.

    1985-01-01

    The Rustler Formation is the uppermost evaporite-bearing unit in the Permian Ochoan series in southeastern New Mexico. It rests on the Salado Formation which includes the salt beds where the mined facility for the Waste Isolation Pilot Plant (WIPP) is being constructed. An understanding of the physical stratigraphy of the Rustler Formation is pertinent to studies of the WIPP site because some portions of the Rustler are water-bearing and may provide paths for circulating waters to come into contact with, and dissolve, evaporites within the Ochoan sequence. Knowledge of the processes, magnitude, and history of evaporite dissolution in the vicinity of the WIPP site is important to an evaluation of the integrity of the site. 2 refs., 2 figs

  13. Planets around pulsars - Implications for planetary formation

    Science.gov (United States)

    Bodenheimer, Peter

    1993-01-01

    Data on planets around pulsars are summarized, and different models intended to explain the formation mechanism are described. Both theoretical and observational evidence suggest that very special circumstances are required for the formation of planetary systems around pulsars, namely, the prior presence of a millisecond pulsar with a close binary companion, probably a low mass main-sequence star. It is concluded that the discovery of two planets around PSR 1257+12 is important for better understanding the problems of dynamics and stellar evolution. The process of planetary formation should be learned through intensive studies of the properties of disks near young objects and application of techniques for detection of planets around main-sequence solar-type stars.

  14. 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…

  15. Assessment of gender understanding of classroom discipline in ...

    African Journals Online (AJOL)

    The study aimed to establish females and males primary teachers' understanding of classroom discipline, the strategies that they apply in dealing with misbehaviour and their knowledge and awareness of discipline models. The study applied a mixed method approach, the dominant less dominant format. Both females and ...

  16. Understanding coastal morphodynamic patterns from depth-averaged sediment concentration

    NARCIS (Netherlands)

    Ribas, F.; Falques, A.; de Swart, H. E.; Dodd, N.; Garnier, R.; Calvete, D.

    This review highlights the important role of the depth-averaged sediment concentration (DASC) to understand the formation of a number of coastal morphodynamic features that have an alongshore rhythmic pattern: beach cusps, surf zone transverse and crescentic bars, and shoreface-connected sand

  17. Barrier cell sheath formation

    International Nuclear Information System (INIS)

    Kesner, J.

    1980-04-01

    The solution for electrostatic potential within a simply modeled tandem mirror thermal barrier is seen to exhibit a sheath at each edge of the cell. The formation of the sheath requires ion collisionality and the analysis assmes that the collisional trapping rate into the barrier is considerably slower than the barrier pump rate

  18. Formation of topological defects

    International Nuclear Information System (INIS)

    Vachaspati, T.

    1991-01-01

    We consider the formation of point and line topological defects (monopoles and strings) from a general point of view by allowing the probability of formation of a defect to vary. To investigate the statistical properties of the defects at formation we give qualitative arguments that are independent of any particular model in which such defects occur. These arguments are substantiated by numerical results in the case of strings and for monopoles in two dimensions. We find that the network of strings at formation undergoes a transition at a certain critical density below which there are no infinite strings and the closed-string (loop) distribution is exponentially suppressed at large lengths. The results are contrasted with the results of statistical arguments applied to a box of strings in dynamical equilibrium. We argue that if point defects were to form with smaller probability, the distance between monopoles and antimonopoles would decrease while the monopole-to-monopole distance would increase. We find that monopoles are always paired with antimonopoles but the pairing becomes clean only when the number density of defects is small. A similar reasoning would also apply to other defects

  19. The formation of galaxies

    International Nuclear Information System (INIS)

    Gunn, J.E.

    1983-01-01

    The presently fashionable ideas for galaxy formation are reviewed briefly, and it is concluded that the standard isothermal heirarchy fits the available data best. A simple infall picture is presented which explains many of the observed properties of disk galaxies. (orig.)

  20. Reconsidering Formative Measurement

    Science.gov (United States)

    Howell, Roy D.; Breivik, Einar; Wilcox, James B.

    2007-01-01

    The relationship between observable responses and the latent constructs they are purported to measure has received considerable attention recently, with particular focus on what has become known as formative measurement. This alternative to reflective measurement in the area of theory-testing research is examined in the context of the potential…

  1. Chlorination and chloramines formation

    International Nuclear Information System (INIS)

    Yee, Lim Fang; Mohd Pauzi Abdullah; Sadia Ata; Abbas Abdullah; Basar IShak; Khairul Nidzham

    2008-01-01

    Chlorination is the most important method of disinfection in Malaysia which aims at ensuring an acceptable and safe drinking water quality. The dosing of chlorine to surface water containing ammonia and nitrogen compounds may form chloramines in the treated water. During this reaction, inorganic and organic chloramines are formed. The recommended maximum acceptable concentration (MAC) for chloramines in drinking water is 3000 μg/L. The production of monochloramine, dichloramine and trichloramine is highly dependent upon pH, contact time and the chlorine to ammonia molar ratio. The purpose of this study is to examine the formation of chloramines that occur upon the chlorination during the treatment process. Chloramines were determined using the N,N-diethyl-p-phenylenediamine (DPD) colorimetric method. The influences of ammonia, pH and chlorine dosage on the chloramines formation were also studied. This paper presents a modeling approach based on regression analysis which is designed to estimate the formation of chloramines. The correlation between the concentration of chloramines and the ammonia, pH and chlorine dosage was examined. In all cases, the quantity of chloramines formed depended linearly upon the amount of chlorine dosage. On the basis of this study it reveals that the concentration of chloramines is a function of chlorine dosage and the ammonia concentration to the chlorination process. PH seems to not significantly affect the formation of chloramines. (author)

  2. 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)

  3. 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

  4. Syntactic Formats for Free

    DEFF Research Database (Denmark)

    Klin, Bartek; Sobocinski, Pawel

    2003-01-01

    A framework of Plotkin and Turi’s, originally aimed at providing an abstract notion of bi-simulation, is modified to cover other operational equivalences and preorders. Combined with bi-algebraic methods, it yields a technique for the derivation of syntactic formats for transition system specific...

  5. Formation of double layers

    International Nuclear Information System (INIS)

    Leung, P.; Wong, A.Y.; Quon, B.H.

    1981-01-01

    Experiments on both stationary and propagating double layers and a related analytical model are described. Stationary double layers were produced in a multiple plasma device, in which an electron drift current was present. An investigation of the plasma parameters for the stable double layer condition is described. The particle distribution in the stable double layer establishes a potential profile, which creates electron and ion beams that excite plasma instabilities. The measured characteristics of the instabilities are consistent with the existence of the double layer. Propagating double layers are formed when the initial electron drift current is large. Ths slopes of the transition region increase as they propagate. A physical model for the formation of a double layer in the experimental device is described. This model explains the formation of the low potential region on the basis of the space charge. This space charge is created by the electron drift current. The model also accounts for the role of ions in double layer formation and explains the formation of moving double layers. (Auth.)

  6. Ecological Understanding 2: Transformation--A Key to Ecological Understanding.

    Science.gov (United States)

    Carlsson, Britta

    2002-01-01

    Describes the structure and general features of the phenomenon of ecological understanding. Presents qualitatively different ways of experiencing cycling of matter and the flow of energy in the context of ecosystems. The idea of transformation is key to the development of ecological understanding. (Contains 17 references.) (Author/YDS)

  7. 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…

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

    Science.gov (United States)

    Neuner-Jehle, Stefan; Senn, Oliver; Wegwarth, Odette; Rosemann, Thomas; Steurer, Johann

    2011-04-05

    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. 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. 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). 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.

  9. 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.

  10. Understanding the Irradiation Behavior of Zirconium Carbide

    International Nuclear Information System (INIS)

    Motta, Arthur; Sridharan, Kumar; Morgan, Dane; Szlufarska, Izabela

    2013-01-01

    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 (>450ee)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 800ee)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

  11. 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

  12. ESTHETIC KNOWLEDGE WHICH AFFECTS THE FORMATION AND THE UNDERSTANDING PROCESS OF THE LITERARY WORK EDEBİ ESERİN OLUŞUM VE ANLAMA SÜRECİNİ ETKİLEYEN BİR ÖGE OLARAK ESTETİK BİLGİ

    Directory of Open Access Journals (Sweden)

    Alpay Doğan YILDIZ

    2010-01-01

    Full Text Available ÖZETEsthetic, which is the knowledge about the beauty in general, is a speafically a set of knowledge based upon the relation bettween the beauty and the art work that can be acknowledged as an appearence of a special kind formed by the artist. The literary art, which is a piece of art by itself, has its own different beauty concepts stemming from diverse apprehension. Therefore with the prospect of assessment and comprehension of the literary work, the role by the help of which we can see the underlying beauty of the art cannot be ignored. In this piece of writing, the importance of esthetic knomledge in the process of assesment and formation of the piece of art will be dwelt on while staying more focused the frame of literary art. Genel anlamda güzel hakkındaki bilgi olan estetik, daha dar anlamda güzelliğin sanatçı tarafından oluşturulan özel bir yapıdaki görünüşü olan sanat eseri ile ilişkisi üzerinde duran bilgi alanıdır. Bir sanat eseri olan edebi eserin oluşumunda da farklı kabullerden kaynaklanan farklı güzellik anlayışları vardır. Bir sanat eserini anlayıp değerlendirmede eserin gerisindeki güzellik anlayışını bilmenin rolü inkâr edilemez. Bu yazıda daha çok edebi eser çerçevesinde kalarak sanat eserinin oluşum ve değerlendirme sürecinde estetik bilginin yeri üzerinde durulacaktır.

  13. Medusae Fossae Formation

    Science.gov (United States)

    2002-01-01

    (Released 10 April 2002) The Science This THEMIS visible image was acquired near 7o S, 172o W (188o E) and shows a remarkable martian geologic deposit known as the Medusae Fossae Formation. This Formation, seen here as the raised plateau in the upper two-thirds of the image, is a soft, easily eroded deposit that extends for nearly 1,000 km along the equator of Mars. In this region the deposit has been heavily eroded by the wind to produce a series of linear ridges called yardangs. These parallel ridges point in direction of the prevailing winds that carved them, and demonstrate the power of martian winds to sculpt the dry landscape of Mars. The Medusae Fossae Formation has been completely stripped from the surface in the lower third of the image, revealing a harder layer below that is more resistant to wind erosion. The easily eroded nature of the Medusae Fossae Formation suggests that it is composed of weakly cemented particles, and was most likely formed by the deposition of wind-blown dust or volcanic ash. Several ancient craters that were once completely buried by this deposit are being exposed, or exhumed, as the overlying Medusae Formation is removed. Very few impact craters are visible on this Formation, indicating that the surface seen today is relatively young, and that the processes of erosion are likely to be actively occurring. The Story Medusa of Greek mythology fame, the name-giver to this region, had snaky locks of hair that could turn a person to stone. Wild and unruly, this monster of the underworld could certainly wreak havoc on the world of the human imagination. As scary as she was, Medusa would have no advantage over the fierce, masterful winds blowing across Mars, which once carved the streaky, terrain at the top of this image. Wild and whipping, these winds have slowly eroded away the 'topsoil,' revealing ancient craters and other surface features they once covered. The loosely cemented particles of this 'topsoil' are likely made up of dust

  14. 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…

  15. Understanding Medicare Prescription Drug Coverage

    Science.gov (United States)

    ... to know what your insurance company is paying…Health Insurance: Understanding What It CoversRead Article >>Insurance & BillsHealth Insurance: Understanding What It CoversYour insurance policy lists a package of medical benefits such as tests, drugs, and treatment services. These ...

  16. 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...

  17. 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…

  18. 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…

  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. Artistic understanding as embodied simulation.

    Science.gov (United States)

    Gibbs, Raymond W

    2013-04-01

    Bullot & Reber (B&R) correctly include historical perspectives into the scientific study of art appreciation. But artistic understanding always emerges from embodied simulation processes that incorporate the ongoing dynamics of brains, bodies, and world interactions. There may not be separate modes of artistic understanding, but a continuum of processes that provide imaginative simulations of the artworks we see or hear.

  1. 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)

  2. 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

  3. The format of things

    DEFF Research Database (Denmark)

    Jørnø, Rasmus Leth

    this conception is identified as “the Format of Things.” The format is embedded in our everyday thinking. In relation to design,it is found in the name taken by the design community, that is human-computer interaction (HCI), and it is mirrored in the desktop metaphor, wherein information is conceived...... available. It consists of philosophical considerations on matters of relevance for the design of interfaces. It takes the position that the graphical user interfaces of computers (the Desktop Metaphor or Windows, Icons, Menus, Pointers [‘WIMP’]) that ordinarily come to mind for most people are cognates......The development of novel interfaces is one of the most important current design challenges for the intellectual, cultural and cognitive evolution of human imagination and knowledge work. Unfortunately, the thinking surrounding this design challenge is heavily mired in conceptions that harbor...

  4. 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

  5. Formation of coronal cavities

    International Nuclear Information System (INIS)

    An, C.H.; Suess, S.T.; Tandberg-Hanssen, E.; Steinolfson, R.S.

    1986-01-01

    A theoretical study of the formation of a coronal cavity and its relation to a quiescent prominence is presented. It is argued that the formation of a cavity is initiated by the condensation of plasma which is trapped by the coronal magnetic field in a closed streamer and which then flows down to the chromosphere along the field lines due to lack of stable magnetic support against gravity. The existence of a coronal cavity depends on the coronal magnetic field strength; with low strength, the plasma density is not high enough for condensation to occur. Furthermore, we suggest that prominence and cavity material is supplied from the chromospheric level. Whether a coronal cavity and a prominence coexist depends on the magnetic field configuration; a prominence requires stable magnetic support

  6. Thermodynamics and kinetics of vesicles formation processes.

    Science.gov (United States)

    Guida, Vincenzo

    2010-12-15

    Vesicles are hollow aggregates, composed of bilayers of amphiphilic molecules, dispersed into and filled with a liquid solvent. These aggregates can be formed either as equilibrium or as out of equilibrium meta-stable structures and they exhibit a rich variety of different morphologies. The surprising richness of structures, the vast range of industrial applications and the presence of vesicles in a number of biological systems have attracted the interest of numerous researchers and scientists. In this article, we review both the thermodynamics and the kinetics aspects of the phenomena of formation of vesicles. We start presenting the thermodynamics of bilayer membranes formation and deformation, with the aim of deriving the conditions for the existence of equilibrium vesicles. Specifically, we use the results from continuum thermodynamics to discuss the possibility of formation of stable equilibrium vesicles, from both mixed amphiphiles and single component systems. We also link the bilayer membrane properties to the molecular structure of the starting amphiphiles. In the second part of this article, we focus on the dynamics and kinetics of vesiculation. We review the process of vesicles formation both from planar lamellar phase under shear and from isotropic micelles. In order to clarify the physical mechanisms of vesicles formation, we continuously draw a parallel between emulsification and vesiculation processes. Specifically, we compare the experimental results, the driving forces and the relative scaling laws identified for the two processes. Describing the dynamics of vesicles formation, we also discuss why non equilibrium vesicles can be formed by kinetics control and why they are meta-stable. Understanding how to control the properties, the stability and the formation process of vesicles is of fundamental importance for a vast number of industrial applications. Copyright © 2009. Published by Elsevier B.V.

  7. 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

  8. 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.

  9. 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

  10. Understanding understanding in secondary school science: An interpretive study

    Science.gov (United States)

    O'Neill, Maureen Gail

    This study investigated the teaching of secondary school science with an emphasis on promoting student understanding. In particular, I focused on two research questions: What are the possible meanings of teaching for understanding? And, how might one teach secondary school science for understanding? After semi-structured interviews were conducted with 13 secondary school science teachers, grounded theory methodology was used to interpret the data. As a result of the selective coding process, I was able to identify 14 connected components of teaching for understanding (TfU). The process of TfU involves: puzzle-solving, a specific pedagogy and a conscious decision. The teacher must be a reflective practitioner who has some knowledge of the facets of understanding. The teacher comes to a critical incident or crisis in his or her pedagogy and adopts a mindset which highlights TfU as a personal problematic. Teachers operate with student-centred rather than teacher-centred metaphors. TfU requires a firm belief in and passion for the process, a positive attitude and excellent pedagogical content knowledge. It hinges on a performance view of understanding and demands risk-taking in the science classroom. Abstracting these ideas to a theory led me to the notion of Purposive Teaching . In their purposive-driven role as pedagogues, these teachers have placed TfU at the core of their daily practice. Constraints and challenges facing TfU as well as implications of the findings are discussed. Keywords. science teaching, teaching for understanding, purposive teaching, constructivism, understanding, pedagogy, pedagogical content knowledge, memorization, meaningful learning, reflective practice.

  11. 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.

  12. 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.)

  13. 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…

  14. Understanding Core-Collapse Supernovae

    Science.gov (United States)

    Hix, W. R.; Lentz, E. J.; Baird, M.; Messer, O. E. B.; Mezzacappa, A.; Lee, C.-T.; Bruenn, S. W.; Blondin, J. M.; Marronetti, P.

    2010-03-01

    Our understanding of core-collapse supernovae continues to improve as better microphysics is included in increasingly realistic neutrino-radiationhydrodynamic simulations. Recent multi-dimensional models with spectral neutrino transport, which slowly develop successful explosions for a range of progenitors between 12 and 25 solar mass, have motivated changes in our understanding of the neutrino reheating mechanism. In a similar fashion, improvements in nuclear physics, most notably explorations of weak interactions on nuclei and the nuclear equation of state, continue to refine our understanding of how supernovae explode. Recent progresses on both the macroscopic and microscopic effects that affect core-collapse supernovae are discussed.

  15. Progress in understanding heat transport at JET

    International Nuclear Information System (INIS)

    Mantica, P.; Garbet, X.; Angioni, C.

    2005-01-01

    This paper reports recent progress in understanding heat transport mechanisms either in conventional or advanced tokamak scenarios in JET. A key experimental tool has been the use of perturbative transport techniques, both by ICH power modulation and by edge cold pulses. The availability of such results has allowed careful comparison with theoretical modelling using 1D empirical or physics based transport models, 3D fluid turbulence simulations or gyrokinetic stability analysis. In conventional L- and H-mode plasmas the issue of temperature profile stiffness has been addressed. JET results are consistent with the concept of a critical inverse temperature gradient length above which transport is enhanced by the onset of turbulence. A threshold value R/L Te ∼5 has been found for the onset of stiff electron transport, while the level of electron stiffness appears to vary strongly with plasma parameters, in particular with the ratio of electron and ion heating: electrons become stiffer when ions are strongly heated, resulting in larger R/L Ti values. This behaviour has also been found theoretically, although quantitatively weaker than in experiments. In plasmas characterized by Internal Transport Barriers (ITB), the properties of heat transport inside the ITB layer and the ITB formation mechanisms have been investigated. The plasma current profile is found to play a major role in ITB formation. The effect of negative magnetic shear on electron and ion stabilization is demonstrated both experimentally and theoretically using turbulence codes. The role of rational magnetic surfaces in ITB triggering is well assessed experimentally, but still lacks a convincing theoretical explanation. Attempts to trigger an ITB by externally induced magnetic reconnection using saddle coils have shown that MHD islands in general do not produce a sufficient variation of ExB flow shear to lead to ITB formation. First results of perturbative transport in ITBs show that the ITB is a narrow

  16. "Straitjacket" or "Springboard for Sustainable Learning"? The Implications of Formative Assessment Practices in Vocational Learning Cultures

    Science.gov (United States)

    Davies, Jenifer; Ecclestone, Kathryn

    2008-01-01

    In contrast to theoretical and empirical insights from research into formative assessment in compulsory schooling, understanding the relationship between formative assessment, motivation and learning in vocational education has been a topic neglected by researchers. The Improving Formative Assessment project (IFA) addresses this gap, using a…

  17. Understanding organizational change for alliancing

    NARCIS (Netherlands)

    B.M. Keers, Bianca; van Fenema, Paul C.; 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. 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…

  19. 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 ...

  20. 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

  1. Understanding Windows | Efficient Windows Collaborative

    Science.gov (United States)

    Foundry Foundry New Construction Windows Window Selection Tool Selection Process Design Guidance Installation Replacement Windows Window Selection Tool Assessing Options Selection Process Design Guidance Installation Understanding Windows Benefits Design Considerations Measuring Performance Performance Standards

  2. Understand Your Risk for Arrhythmia

    Science.gov (United States)

    ... is likely monitoring your heart rhythm with regular EKGs ( electrocardiograms ). But arrhythmias that occur infrequently may not ... patient sheets Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  3. Guide to Understanding Facial Palsy

    Science.gov (United States)

    ... does not block the child’s vision. A watchful, conservative approach is usually best for a child with ... how can children’s craniofacial association (cca) benefit my family? c CA understands that when one family member ...

  4. Understanding Adult Overweight and Obesity

    Science.gov (United States)

    ... Step in the Right Direction Understanding Adult Overweight & Obesity View or Print All Sections Definition & Facts The terms “overweight” and “obesity” refer to body weight that is greater than ...

  5. 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 ...

  6. Understanding Pregnancy and Birth Issues

    Science.gov (United States)

    ... Navigation Bar Home Current Issue Past Issues Understanding Pregnancy and Birth Issues Past Issues / Winter 2008 Table ... turn Javascript on. What is a High-Risk Pregnancy? All pregnancies involve a certain degree of risk ...

  7. Understanding Traumatic Stress in Children

    Science.gov (United States)

    ... content Experts Careers Contracting Contact Search form Search American Institutes for Research About Us Our Topics Client Services News & Events You are here Home 22 Apr 2013 Report Understanding Traumatic Stress in Children Supporting Children and Families After Traumatic ...

  8. 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.

  9. 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 ...

  10. Understanding human DNA sequence variation.

    Science.gov (United States)

    Kidd, K K; Pakstis, A J; Speed, W C; Kidd, J R

    2004-01-01

    Over the past century researchers have identified normal genetic variation and studied that variation in diverse human populations to determine the amounts and distributions of that variation. That information is being used to develop an understanding of the demographic histories of the different populations and the species as a whole, among other studies. With the advent of DNA-based markers in the last quarter century, these studies have accelerated. One of the challenges for the next century is to understand that variation. One component of that understanding will be population genetics. We present here examples of many of the ways these new data can be analyzed from a population perspective using results from our laboratory on multiple individual DNA-based polymorphisms, many clustered in haplotypes, studied in multiple populations representing all major geographic regions of the world. These data support an "out of Africa" hypothesis for human dispersal around the world and begin to refine the understanding of population structures and genetic relationships. We are also developing baseline information against which we can compare findings at different loci to aid in the identification of loci subject, now and in the past, to selection (directional or balancing). We do not yet have a comprehensive understanding of the extensive variation in the human genome, but some of that understanding is coming from population genetics.

  11. Fracturing of subterranean formations

    Energy Technology Data Exchange (ETDEWEB)

    Kiel, O.M.; Kidwell, A.L.

    1968-03-19

    This method of propping fractured formations results in high conductivities. In the method, certain naturally occurring crystals are used as propping agents. Suitable crystals include garnet, corundum, zircon, rutile, high-temperature quartz, and other minerals which have Moh's hardness values of about 6 or greater and weather out as individual crystals of about 40 mesh or larger. These are said to result in permeabilities significantly higher than those obtained with ordinary quartz sand, metallic shot, glass beads, plastic particles, walnut hulls, or similar materials. (10 claims)

  12. Situated Formative Feedback

    DEFF Research Database (Denmark)

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

    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...... theoretical textual analysis method. Asynchronous written dialogue from an online master’s course at Aalborg University forms the empirical basis of the study. The findings suggests in general that students play an essential role in SFF and that students and educators are equal in the COP, but holds different...

  13. Superclusters and galaxy formation

    Energy Technology Data Exchange (ETDEWEB)

    Einasto, J; Joeveer, M; Saar, E [Tartu Astrophysical Observatory, Toravere, Estonia (USSR)

    1980-01-03

    A study of the structure of superclusters in the Southern galactic hemisphere using Zwicky clusters as principal tracers of the large-scale structure of the Universe is reported. The data presented suggest that the formation of galaxies was a two stage process involving larger spatial dimensions than earlier workers have postulated. In the first stage proto-superclusters and big holes had to form from the non-dissipative dark matter while in the second hot gas, by cooling and settling down into the potential wells caused by dark matter, will form galaxies and clusters of galaxies.

  14. Dark Energy and Structure Formation

    International Nuclear Information System (INIS)

    Singh, Anupam

    2010-01-01

    We study the gravitational dynamics of dark energy configurations. We report on the time evolution of the dark energy field configurations as well as the time evolution of the energy density to demonstrate the gravitational collapse of dark energy field configurations. We live in a Universe which is dominated by Dark Energy. According to current estimates about 75% of the Energy Density is in the form of Dark Energy. Thus when we consider gravitational dynamics and Structure Formation we expect Dark Energy to play an important role. The most promising candidate for dark energy is the energy density of fields in curved space-time. It therefore become a pressing need to understand the gravitational dynamics of dark energy field configurations. We develop and describe the formalism to study the gravitational collapse of fields given any general potential for the fields. We apply this formalism to models of dark energy motivated by particle physics considerations. We solve the resulting evolution equations which determine the time evolution of field configurations as well as the dynamics of space-time. Our results show that gravitational collapse of dark energy field configurations occurs and must be considered in any complete picture of our universe.

  15. SPMHD simulations of structure formation

    Science.gov (United States)

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

    2018-05-01

    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 magnetohydrodynamic (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. Engagement: Looking beyond the mirror to understand action understanding.

    Science.gov (United States)

    Reddy, Vasudevi; Uithol, Sebo

    2016-03-01

    In this paper, we argue that the current focus on mirroring as the route to explaining the development of action understanding is misleading and problematic. It facilitates a fundamentally spectatorial stance, ignoring engagement and dialogue; it focuses on similarity between self and other and neglects difference; and it succumbs to the static terminology of mechanism rather than a dynamic language of process. Contrary to this view, dialogic exchanges are evident from the start of life, revealing infants' ability to engage with and respond appropriately to actions that are outside their own motor repertoire. We suggest that engagement rather than mirroring better accounts for many current findings in action understanding. The neurological evidence to date shows that action perception involves a process of continuous synchronization and change, suggesting that it might be more fruitful for research and theory to look beyond mirroring and instead adopt dynamic processual explanations of action understanding within interaction. © 2015 The British Psychological Society.

  17. 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...

  18. Urbanization and Slum Formation

    Science.gov (United States)

    Phua, Kai Hong

    2007-01-01

    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. PMID:17387618

  19. A Mesoproterozoic iron formation

    Science.gov (United States)

    Canfield, Donald E.; Zhang, Shuichang; Wang, Huajian; Wang, Xiaomei; Zhao, Wenzhi; Su, Jin; Bjerrum, Christian J.; Haxen, Emma R.; Hammarlund, Emma U.

    2018-04-01

    We describe a 1,400 million-year old (Ma) iron formation (IF) from the Xiamaling Formation of the North China Craton. We estimate this IF to have contained at least 520 gigatons of authigenic Fe, comparable in size to many IFs of the Paleoproterozoic Era (2,500–1,600 Ma). Therefore, substantial IFs formed in the time window between 1,800 and 800 Ma, where they are generally believed to have been absent. The Xiamaling IF is of exceptionally low thermal maturity, allowing the preservation of organic biomarkers and an unprecedented view of iron-cycle dynamics during IF emplacement. We identify tetramethyl aryl isoprenoid (TMAI) biomarkers linked to anoxygenic photosynthetic bacteria and thus phototrophic Fe oxidation. Although we cannot rule out other pathways of Fe oxidation, iron and organic matter likely deposited to the sediment in a ratio similar to that expected for anoxygenic photosynthesis. Fe reduction was likely a dominant and efficient pathway of organic matter mineralization, as indicated by organic matter maturation by Rock Eval pyrolysis combined with carbon isotope analyses: Indeed, Fe reduction was seemingly as efficient as oxic respiration. Overall, this Mesoproterozoic-aged IF shows many similarities to Archean-aged (>2,500 Ma) banded IFs (BIFs), but with an exceptional state of preservation, allowing an unprecedented exploration of Fe-cycle dynamics in IF deposition.

  20. Endocytosis and Enamel Formation

    Directory of Open Access Journals (Sweden)

    Cong-Dat Pham

    2017-07-01

    Full Text Available Enamel formation requires consecutive stages of development to achieve its characteristic extreme mineral hardness. Mineralization depends on the initial presence then removal of degraded enamel proteins from the matrix via endocytosis. The ameloblast membrane resides at the interface between matrix and cell. Enamel formation is controlled by ameloblasts that produce enamel in stages to build the enamel layer (secretory stage and to reach final mineralization (maturation stage. Each stage has specific functional requirements for the ameloblasts. Ameloblasts adopt different cell morphologies during each stage. Protein trafficking including the secretion and endocytosis of enamel proteins is a fundamental task in ameloblasts. The sites of internalization of enamel proteins on the ameloblast membrane are specific for every stage. In this review, an overview of endocytosis and trafficking of vesicles in ameloblasts is presented. The pathways for internalization and routing of vesicles are described. Endocytosis is proposed as a mechanism to remove debris of degraded enamel protein and to obtain feedback from the matrix on the status of the maturing enamel.